Palaeoenvironmental interpretation of fluvial red beds by statistical analysis of palaeocurrent data: Examples from the buntsandstein (lower triassic) of the eifel and bavaria in the German basin (middle Europe)

Sedimenta~, Geology, 41 (1985) 1-74 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands

PALAEOENVIRONMENTAL BY

STATISTICAL

FROM

THE

INTERPRETATION

ANALYSIS

BUNTSANDSTEIN

BAVARIA IN THE GERMAN

OF

OF

1

FLUVIAL

PALAEOCURRENT

(LOWER

TRIASSIC)

BASIN (MIDDLE

DATA: OF THE

RED

BEDS

EXAMPLES EIFEL AND

EUROPE)

DETLEF MADER AND THOMAS TEYSSEN

Rbttgerstrasse 20, D-3000 Hannover 91 (F.R.G.) Pieter- Meinersstraat 34, 2597 VL The Hague (The Netherlands) (Received May, 16, 1983; revised and accepted April 10, 1984)

ABSTRACT

Mader, D. and Teyssen, T., 1985. Palaeoenvironmental interpretation of fluvial red beds by statistical analysis of palaeocurrent data: examples from the Buntsandstein (Lower Triassic) of the Eifel and Bavaria in the German Basin (Middle Europe). Sediment Geol., 41: 1-74.

Palaeocurrent data from parts of the Upper Buntsandstein (Lower Triassic) of both the western (Eifel: Kyllburg-Schichten) and eastern (Bavaria: Plattensandstein) margin of the German Triassic Basin (Middle Europe) have been interpreted by circular directional statistics, eigenvalue and eigenvector analysis, autocorrelation analysis and vector trend analysis. Examination of current roses, histograms of normalized vector magnitudes and plots, of circular skewness of the distribution vs. circular kurtosis, together with the palaeocurrent plots indicate bimodal palaeocurrent distributions with bipolar orientations within long, short and very short sedimentary sequences. Subset I of the directional data is interpreted to represent larger, more continuous flows in a high-energy regime of probably perennial type, whereas subset II may represent smaller, partially episodic flows of probably ephemeral type with larger variability in direction and flow regime; transport and sedimentation rates being significantly smaller than during deposition of subset I. A part of the bimodal palaeocurrent distributions within short sedimentary sequences fits rather well into the general transport pattern. Other bipolarities are primarily interpreted as effects of superimposition of channels of different orientations as well as of main channels and crevasse-splay channels, and condensation of deposition from discontinuous or episodic flows. The main mechanism creating the vertical succession of various directions is stacking of different substratum members to multistorey complexes by primary-depositional restriction of formation and/or secondaryerosional removal of topstratum sediments. The occasional occurrence of herring-bone cross-stratification representing bipolarities within very short depositional sequences, testifies to probably episodic and random changes in water surface slopes allowing currents to reverse locally. Examination of long sedimentary sequences by autocorrelation analysis reveals changes of transport directions with time in a sinusoidal manner, indicating a conformable environmental development of the alluvial watercourses which reflects a time-cyclic trend of sedimentation by spatially continuous and time-concordant shifting of the channel system. The results of the statistical analysis enable an enhanced palaeoenvironmental reconstruction of the alluvial network which fits best to a transitional meandering-thalweg-braided 0037-0738/85/$03.30

© 1985 Elsevier Science Publichers B.V.

channel pattern. Comparison of the statistical results, especially in the light of vector trend surface

analysis, clearly reflects the different palaeogeographicpositions of both investigated areas, but rules out only minor influences of regionally different palaeoslopes on the alluvial depositional environment, wilh the basic principles of fluvial style at the western margin (Eifel) generally matching those at the eastern margin (Bavaria) of the German Basin.

INTRODUCTION

Palaeocurrent interpretation from cross-stratification measurements taken from surface exposures (first suggested by Sorby, 1859; see also Allen 1963a) has been used in palaeogeographic studies for over 100 years and especially in the last decades has become an increasingly important sedimentological tool (an overview of the vast literature is given by Potter and Pettijohn, 1977) partially accompanied by the possibility to extend its applicability to the subsurface by dipmeter wireline logging in wells (Dresser Atlas, 1980; Van Wijhe et al., 1980; Schlumberger, 1981; L~thi, 1983; Glennie, 1983). In the Mid-European Triassic, cross-stratification fabric analysis and directional evaluation have focussed on two formations: the Lower Triassic Buntsandstein Formation (for literature review, see Mader, 1980a, 1981c) and the Upper Triassic Schilfsandstein Formation (Wurster, 1964; Stets and Wurster, 1977). Most palaeowind and palaeocurrent direction studies on Triassic rocks carried out in the last years (for literature compilation cf. Table I; other references are listed in Mader, 1980a, 1981c) are based on application of conventional means of measurement treatment. Statistical data analysis was used in the G e r m a n Buntsandstein by Teyssen and Vossmerb~umer (1980). In other formations, computer-aided interpretations were made by Rao and Sengupta (1972), Miall (1974), Parks (1974), Button (1975), Turner (1977), Kruhl (1978), Freeman and Pierce (1979), Plummer and Leppard (1979), Cooper and Marshall (1981), Khan and Casshyap (1981) and M~kel (1982). In the Lower Triassic Buntsandstein Formation of the Eifel at the western margin of the G e r m a n Triassic Basin, sedimentological interpretations of aeolian and fluvial deposits (Mader, 1980b, 1981a, b, 1982a) have been carried out in recent years, as well as reconstructions of palaeowind and palaeocurrent directions (Mader, 1980a, 1981c). Cross-bedding investigations have been made in the same period in the Buntsandstein of Northern Bavaria at the eastern margin of the G e r m a n Basin (Vossmerb~umer, 1979; Teyssen and Vossmerb~umer, 1979, 1980). The aim of this study is to perform a modern statistical analysis of the data gathered by Mader (1981c) in the Eifel and by Vossmerb~umer (1979) and Teyssen and Vossmerb~umer (1980) in Bavaria to derive further palaeogeographical conclusions and to compare the depositional environments in different parts of the Mid-European Buntsandstein Basin during a nearly equivalent stratigraphic interval in view of fluvial palaeotransport.

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Fig. 1. Geological sketch of Central Middle Europe (redrawn after Walther and Zitzmann, 1969) showing the outcrop of the Buntsandstein Formation (black). Insert map in upper left: Geological sketch of the Western Eifel (redrawn after Dahlgrim, 1939). Legend: 1 = Devonian basement; 2 = Buntsandstein; 3 = Muschelkalk and Keuper; Tertiary and Quaternary removed, tectonics not respected. Insert map in lower right: Geological sketch of Northern Bavaria (redrawn after Wolniczak, 1981). Legend: 1 = crystalline and sedimentary basement; 2 = Buntsandstein; 3 = Muschelkalk and Keuper; Tertiary and Quaternary removed, tectonics not respected).

G E O L O G I C A L S E T T I N G OF T H E EIFEL A N D BAVARIA

In the Eifel area at the western margin of the Mid-European Triassic Basin, the continental Buntsandstein red beds unconformably overlie the folded and eroded Variscan basement of the Rhenish Massif (cf. Fig. 1). Some 200 m of predominantly

TABLE I Overview of palaeocurrent and palaeowind direction studies in Triassic formations (selected compilation of papers from 1960 onwards; additional references are listed in Mader, 1980a, 1981c). Compilation terminated in January 1984

PALAEOCURRENT AND PALAEOWIND DIRECTION STUDIES IN TRIASSIC FORMATIONS TYPE

CONTINENT

P

COUNTRY

Germany(FRO)

A

AREA Effel Pfalz Soar area Francoma Hessian Depression

Luxembour 9

L

Vosges Germany (GDR)

A

Poland

E

Europe Hungary Austria

0

Great Brdam

C Scandlnovia

U

Spain

R R

Africa

E N

North America

T S P A L A E O W I N D S

Asia Australia Antarctica

Morocco South Africa, Lesotho Zululand Colorado Plateau New Mexico British Columbia Connecticut Nova Scotia India

Germany (FRG)

Europe Great Britain

Scandinavia

Africa North America

South America

Southwest Africa Colorado Plateau Connecticut Nova Scotia Brazi(

Thuringqa Sudeties Holy Cross Mountains Tatta Mountains Mecsek Mountmns Western Alps Cheshire/England Devon/England Moray Firth/Scotland North Mmch/Scotland Danish-Norwegian Basin East Greenland Pyrenees Iberian Ranges Iberian Meseta Atlas Mountains Karoo Basin Nongorna Graben

REFERENCES MADER {1980 a, 1981 C) SCHIEDT (1968 L BACKHAUS (1975), DACHROTH (1980) PERRIAUX & MULLER (1961i, SCHALL (t 968), JUNGBLUT (1982) VOSSMERBAUMER(1979}, TEYSSEN&VOSSMERBAUMER fig?g, 1980) WYCISK [198l,} WIE BEL (1968i PERRIAUX(1961),COUREL et at (1973}, DURAND (1978} PERRIAUX & MULLER (1961} GRUMBI (197L) MROCZKOWSKI 0989, t972, 19771 SENKOWICZOWA &SLACZKA (1982( DZULYNSKI &GRADZINSKI (1960} SZABO (1965}~NAGY (1968} EISBACHER (1983} THOMPSON (t970), STEEL&THOMPSON {1983)

LAMING (1966,1982) TROMMESTAD {1982) JOHNSEN (1981) BERTELSEN (1980) CLEMMENSEN (1978,1980) NAGTEGAAL (1969), LUCAS (1977) RAMOS (1979),SOPENA (1979),RAMOS&SOPENA (1983) FERNANDEZ (1977}, DABRIO &FERNANDEZ (1980) MATTIS {1977} TURNER (19??, 1983) TURNER &WHATELEY (1983) POOLE (1961, 196/*) STEWART et al (19?2i, M I D D L E T O N &BLAKEY (1983) San Juan Basin KURTZ &ANDERSON (1980} Northeastern BC PELLETIER (1965) HUBERT et al (1978,1979) North-Central Mass WESSEL ( 1989 ) St Mary's Bay HUBERT & HYDE 0982) Pranhita-Oodovari Volley RAG & SENGUPTA (t966), SENGUPTA (197Q1 Sydney Basin McDONNELL [1974} Beardmore Glacier area ~IARRETT (1969,1970) MADER (1980 a, 19820) Pfalz and Soar area BACHROTH (1980} I Hessian Depress*on I WYCISK (1984) Helgoland WURSTER (1960), CLEMMENSEN (1979,1981) Holy Cross Mountains GRADZINSKI et ol (1979) Cheshire/England THOMPSON (1969, 1970I Devon~England LAMING (1986,1982} Moray Firth/Scotland TROMMESTAD (1982 L GLENNIE & BULLER {19831 North Minch/Scotland JOHNSEN {1981} asia Gtaben RAMBERG&SPJELDNAES (1978) East Greenland CLEMMENSEN {1978, 1979, 1981) Karoo Basin STAVRAKIS (1980( POOLE (1962) MIDDLETON & BLAKEY (1983) HUBERT (1975( I Fundy Basin HUBERT $ MERTZ {1980) FARIA (1982)

fluvial sediments were deposited in the Eifel north-south depression zone. Subsequent erosion has split the original extension of the Mesozoic cover into several fragments; of these regions, the Northern Trier area around Kyllburg and the Oberbettingen area (cf. Fig. 1) are considered in this study. The Scythian part of the Upper Buntsandstein (the Zwischenschichten) is divided into three members: Usch-Schichten, Malbergweich-Schichten and KyllburgSchichten (cf. Table II) which are built up of fluvial cyclothems ideally consisting of channel lag deposits, channel bar sediments, sandy and silty-clayey topstratum deposits and palaeosols (Mader, 1981b). The thickness of the Kyllburg-Schichten sequence ranges between 50 and 90 m. In northern Bavaria, near the eastern margin of the German Triassic Basin, the terrestrial Buntsandstein sequence is of quite different composition from that at the western border (for correlation of the Buntsandstein successions in various parts of the depositional area cf. Richter-Bernburg, 1974). The lower and middle portions of the sequence are predominantly of fluvial origin, whereas the upper part reflects an increasing marine influence. The Scythian part of the Upper Buntsandstein (the ROt 1-3, cf. Table II) is characterized by the Plattensandstein Formation which is the only thicker sandy complex within the silty-clayey R6t series. The Plattensandstein is a diachronous sand body generally thinning from south to north (Schuster, 1934; cf. also Gronemeier and Martini, 1973), and its topmost sand units become progressively younger to the south (Backhaus, 1981). The thickness of the Plattensandstein Formation in the southern part of the investigated area, between the Odenwald and Rh/3n mountains, is about 50 m and declines to only some metres in the northern part. The diminishing thickness is accompanied by decreasing grain sizes.

TABLE II Stratigraphy of the Upper Buntsandstein (LowerTriassic) in western Eifel (western margin of the German Basin) and northern Bavaria (eastern margin of the German Basin), compiled after Schuster (1934), Leitz (1976), Richter-Bernburg (1974) and Mader (1979, 1982)

G

ALPINE SERIES

E

R

M

A

N

F

L

O

ANISIAN UPPER BU'N~

W

E

R

M

A

C

I

E

S

NORTHERN BAVARIA (SCHUSTER 193/,. LEITZ 19"/6)

WESTERN EIFEL (MADER 19"/9.1982}

U

S

C

H

VOLTZIENSANDSTEIN

E

L

K

A

L

K

MYOPHORIEN-SCHICHTEN OBERE

KYLLBURG-SCHICHTEN

ROTTONE~ PLATTENMALBERGWEICH-SCHICHTEN UNTE~REROTTONE~SAND_ _ ~ S T E I N USCH-SCHICHTEN CHIROTHERIEN-SCH.~__~. i

SANDSCYTHIAN

STEIN M

I

D "D

L

E

B

U

N

T

S

A

N

D

S

T

E

I

N

The cross-bedding measurements in the Eifel to be discussed here have been nearly exclusively taken from the Kyllburg-Schichten and derive in Bavaria from the Plattensandstein. S E D I M E N T O L O G Y OF THE E I F E L K Y L L B U R G - S C H I C H T E N A N D THE B A V A R IA N PLATTEN SANDSTEIN

The two formations which have been studied in terms of palaeocurrent distributions are described and interpreted in the light of sedimentology as follows. In contrast to the Kyllburg-Schichten, where reference can be made to earlier investigations of depositional environments (Mader, 1981b, 1982b, 1983b, 1984a), the Plattensandstein, which up to now had not been interpreted in detail, is discussed here more extensively (the sedimentary milieu of the Kyllburg-Schichten is only presented in rough outline). Since centuries both formations were widely used locally and regionally as building stones and are nowadays still exploited in several large quarries which, together with numerous old quarries and with natural sections in river valleys and rivulet gorges, provide an abundance of outcrops available for sedimentological interpretation and palaeocurrent analysis.

Kyllburg-Schichten Description The Kyllburg-Schichten are mainly composed of thick, often multistorey sandstone complexes. The sandstones are mostly medium-grained and rarely contain some isolated pebbles. Carbonate breccias (conglomeratic cornstones, Br6ckelbanke; Mader, 1980c), representing intraformational reworking horizons of pedogenic carbonate concretions from caliches (calcretes), are intercalated into the sandy sequence. In the sandstones both tabular and trough cross-bedding (alpha-, omikron-, and pi-types, sensu Allen, 1963b) occur, as well as horizontal lamination. The sandstones consist predominantly of quartz (45-50%), feldspar (15-20%), rock fragments (35-40%), and mica (2-5%); the latter often densely draping the bedding planes. Diagenesis is dominated by feldspar neoformation and quartz authigenesis, and the diversity of the postsedimentary processes is highlighted by numerous diagenetic alterations of heavy minerals, even including authigenic growth of stable ubiquistes (Mader, 1981d). The sands are well to very well sorted with sorting values (after Trask, 1932) from 1.22 to 1.45; median grain size ranges from 0.19 to 0.42 with a maximum between 0.19 and 0.28 mrn. Skewness ranges between 0.79 and 1.12, and kurtosis ranges between 0.19 and 0.26 (for representation of grain-size characteristics see Fig. 2; for full compilation of grain-size parameters see Mader, 1981b; further granulometric data are presented by Schrader, 1983, and Berners et al., 1983, 1984).

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z

m

m m

m m

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z

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Z

CROSS-STRATIFICATION

FABRIC

/ J

,Y

/

OBERBETTINGEN

AREA

Interpretation The Kyllburg-Schichten sandstones originated mainly in low- to medium-sinuosity, moderately braided rivers as transverse bars and as upper flow regime plane beds. Sandy and silty-clayey topstratum sediments were laid down in narrow to moderately extensive floodplains in slowly flowing to quiet water. Emergence of overbank areas and extraordinary low stages in the channels led to formation of palaeosols at the tops of the cyclothems (for detailed description and interpretation see Mader, 1981b, 1983b, 1984a). P lattensandstein Description The Plattensandstein is ideally composed of cyclothems consisting of channel bar deposits and overbank sediments, with the coarse member (1-3 m) being generally thicker than the fine member (0.1-2 m). In some cases, however, the substratum deposits are of similar thickness as the topstratum sediments. The passage from coarse member to fine member is either a continuous transition by progressively fining grain size or an abrupt change by rapidly declining grain size. In the lower part of the Plattensandstein sequence, predominantly multistorey channel bar complexes occur, whereas in the upper part of the succession, the cyclothems are more often nearly completely preserved. At its top, the mainly sandy Plattensandstein Formation containing intercalations of silty/clayey sediments is sharply overlain by the primarily silty/clayey R6ttone succession (cf. Plate I-4) which in turn passes upwards into the carbonate Muschelkalk series (the following description is mainly Fig. 2. Relationship between joint pattern and cross-stratification fabric in the Buntsandstein (Lower Triassic) of the Oberbettingen area in the Western Eifel (for geological and topographical situation see Fig. 1). The collection of palaeocurrent data is facilitated by development of two main joint directions in most of the localities which are oriented nearly perpendicularly to each other. The dip direction of the foreset planes is either approximately parallel to one of the joint directions or forms the mean of both joint bundles. Generation of abundant edges in the outcrops by the narrow spacing of the joints favoured easy gathering of true dip direction values of the cross-stratification laminae. The relationship between joint pattern and cross-stratification fabric is the result of the directional coincidence of tectonics and sedimentation. The Eifel N o r t h - S o u t h Zone (from which the Oberbettingen area is the central part) was an elongated depression zone within the surrounding Devonian basement in which the rivers flowed from south to north and the winds blew also from south to north during Buntsandstein deposition. After accumulation and burial of the Buntsandstein sediments, the primary depression zone was partially accentuated by secondary graben-like downfaulting along north-south-trending and associated west east-striking normal faults with vertical separations between a few tens of metres and about one hundred metres. Data compiled from Mader (1976), map simplified and redrawn after Mader (1975) and SchS.fer (1976). Legend of the map: black = Quaternary volcanics, horizontal hachures= Quaternary sediments (valley fillings and terraces of river Kyll), vertical hachures = Muschelkalk (Middle Triassic), white = Buntsandstein (Lower Triassic), stippled = Devonian basement (only represented at the margin of the Buntsandstein plate), thick lines = faults, p. 7: Joint directions (frequency roses of strike direction), p. 8: Dip directions of cross-stratification (frequency roses of dip direction). Width of each sector within the roses = 10 o azimuth. Discussion on p. 20.

10

PLATE I

ll

1 and 2: Bipolar herring-bone cross-stratification in the upper (1) or lower (2) part of some fluvial channel deposit sequences testifies to occasional occurrence of reverse currents under lower-flow regime conditions in various stages of stream aggradation. The main mechanisms creating upstream directed foreset sedimentation are changing water table surface gradients near confluences of streams during flood stage (partially accompanied by whirlpooling effects) and flow separation over channel bars during bankfull discharge. 1: Diameter of figure ca. 45 cm. Middle Buntsandstein, Upper Franconia. Sand pit between Neuenreuth and Sachspfeife at the eastern side of the Rodach valley south of Kronach (Sheet Kronach, r 51660, h 63980). 2: Diameter of figure ca. 1.8 m. Middle Buntsandstein, Solling. Quarry at the southeastern side of the Hennigsbrink southeast of Lobach (Sheet 4123 Stadtoldendorf, r 37160, h 47 470). 3: Cross-stratified channel sediments with counterdipping sets above the basal irregular erosional boundary indicate changing current directions on the floor of the watercourse during early stages of river aggradation. Middle Buntsandstein, Solling. Diameter of figure ca. 1.3 m. Quarry at the southeastern side of the Hoop northwest of Stadtoldendorf (Sheet 4123 Stadtoldendorf, r 42440, h 50610). 4: The passage from the sandy Plattensandstein sequence into the silty-clayey R6ttone succession records rapid burial of the alluvial plain by a coastal mud flat prior to shallow marine transgression. Upper Buntsandstein (Plattensandstein), Mainfranken. Diameter of figure ca. 6 m. Quarry at the southwestern flank of the Mi~hlenberg at the northeastern side of the Kembach valley in Kembach (Sheet 6223 Wertheim, r 45640, h 11 800). 5: Heterolithic longitudinal epsilon-cross-bedded sediments at the top of some transverse cross-stratified channel deposit sequences with internally alternating horizontal-bedding and ripple cross-lamination document occasional occurrence of lateral accretion on flanks of bars in advanced to terminal stages of stream aggradation. The heterolithic composition testifies to fluctuating discharge with changing current velocity under generally lower-flow regime conditions. Middle Buntsandstein, Solling. Length of hammer 29 cm. Quarry at the southeastern side of the Hoop northwest of Stadtoldendorf (Sheet 4123 Stadtoldendorf, r 42 560, h 50 540). 6: Intraformational conglomerates within substratum successions consisting of reworked fragments of silty-clayey overbank deposits and carbonate concretions from calcrete palaeosols reflect considerable vertical and lateral erosion during channel shift, resulting in secondary removal of parts of the floodplain deposits from the sedimentary record. Middle Buntsandstein, Solling. Diameter of figure ca. 20 cm. Quarry at the western side of the Heidbrink southwest of Arholzen (Sheet 4123 Stadtoldendorf, r 38 780, h 47 470). 7: Downsinking of fragments of massive sandstone into laminated, partially silty-clayey sandstone indicates thixotropic quicksand behaviour of arenaceous sediments when loaded rapidly prior to dewatering and desiccation. Liquefaction of the water-saturated underlying sands resulted in division of a continuous sand layer into isolated pillows and downsinking with minor deformation of laminae below the balls. Upper Buntsandstein (Plattensandstein), Mainfranken. Diameter of figure ca. 45 cm. Quarry at the southwestern flank of the Mi~hlenberg at the northeastern side of the Kembach valley in Kembach (Sheet 6223 Wertheim, r 45640, h 11 800). 8: Flute casts on bedding planes of channel sands testify to small-scale vertical erosion by minor turbulences on the bottom of the watercourses during early stages of stream aggradation. Upper Buntsandstein (Plattensandstein), Mainfranken. Diameter of figure ca. 50 cm. Quarry at the eastern side of the Liesengraben valley at the northern end of Wi)stenzell (Sheet 6223 Wertheim, r 47160, h 15 880). 9: Emergence of channel bars during low stage of a river causes deflection of flows at the bar heads, resulting in considerable deviation of current direction with origin of cross-flows and even counter-flows. Superimposition of the various directions within the sedimentary record produces high dispersions of palaeocurrents and separation of the spread into a downstream mode and a cross- to counter-channel mode. Artificial low stage of the Leine river in Hannover-Linden (caused by river management): flow pattern visualized by foam.

12 based on observations in various large outcrops around Kembach and Wi~stenzell between Marktheidenfeld and Wertheim). Coarse member. The substratum sediments consist mainly of medium- to fine-grained and fine-grained, partially silty/clayey, dark red to red-violet sandstones which occur as thick to thin, massive to platy beds (cf. Plate I-4). The mean grain size of the sandstones declines from 0.18 mm in the south to 0.10 mm in the north. The sands are well to very well sorted with sorting values (after Trask, 1932) from 1.1 to 1.6. The sandstones are medium- to large-scale cross-stratified (both tabular and trough type) or horizontal-bedded, with subordinate amounts also ripple crosslaminated. Horizontal stratification is gener°.lly the dominant bedding type, with the cross-stratified sets often being irregularly intercalated into horizontal-laminated successions. In some parts of the sequence, however, thicker and laterally more persistent cross-bedded cosets occur. The sandstones often contain varying amounts of mica flakes which, in the lower parts of the cyclothems, are mainly dispersed within thick beds and increase considerably in abundance towards the top, with the general upwards-fining of the sandstones where the mica flakes are frequently enriched on bedding planes of platy horizontal-laminated sandstones forming dense mica drapes. Thinly bedded papery silty-clayey sandstones consist of alternating mica and quartz laminae of up to 2 mm thickness. The sandstones are mainly lithified by authigenic quartz, sometimes also by neoformed dolomite (the presence and distribution of carbonate cement is often indicated by secondary-epidiagenetic carbonate fillings of joints). Erosional boundaries between successive cross-stratification sets are predominantly even or gently wavy and only occasionally cut with steeper relief of up to 1 m down into the underlying sediments. Channel fills are several metres to some tens of metres wide and up to several metres deep and are mainly filled by homogeneous sand sequences (with occasional intercalations of intraformational conglomerates), subordinately also with alternating sand and silt/clay laminae of several millimetres to some centimetres thickness or with silt/clay successions containing lenticular or wedge-shaped sand intercalations. Within the sandstone sequences, the height of the cross-stratification sets often declines upwards, and in many cases also the angle of foreset inclination within sets diminishes towards the top of the coarse member. Some cross-bedding sets show internal reactivation surfaces generating an intraset fabric. At the top of large- and medium-scale transverse cross-stratification cosets, occasional low-angle heterolithic longitudinal epsilon-cross-bedded sets with internal ripple cross-lamination or horizontal stratification parallel to the master bedding planes occur (Plate 1-5). The longitudinal epsilon-cross-strata are present as solitary sets or as overlapping cosets with steeper cutbanks. Cyclothems are nearly completely developed only in parts of the Plattensandstein sequence. In many portions of the succession, the substratum members are stacked upon each other to form polyphase and multistorey complexes. The individual

13 genetical units are separated by erosional boundaries (Plate I-3) and are further differentiated by concentration of flat silt/clay pebbles at the basal surfaces, trends of decreasing height of cross-stratification sets, trends of bedding types, bioturbated surfaces and layers near the upper boundary, and by intercalation of thin lenses and layers of waning-flow sediments. The waning drapes cover horizontal bedding planes, erosional surfaces and occasionally also cross-stratification foresets and consist mainly of fine-grained, horizontal-laminated or ripple cross-bedded sandstone, silty-clayey sandstone with abundant mica, or silt/clay, dominantly some centimetres, rarely up to several decimetres thick. Within cross-stratification sets, the waning drapes occur on some isolated foreset laminae (which may also be covered by current ripple trains). At the base of channel sandstone sequences, repeated intraformational carbonate breccias representing accumulation of reworked fragments of pedogenic carbonates (cf. Mader, 1980c) occur. These type A Br6ckelb~nke (cf. Mader, 1984b) contain abundant carbonate fragments as well as varying amounts of flat silt/clay pebbles and vivianitized apatitic vertebrate bone splinters (Plate I-6). The carbonate breccias form lenticular or sheet-like units up to several dm thick, or are developed as fillings of either isolated or laterally and vertically overlapping channels up to 5 m wide and 1 m deep. Other reworking horizons of similar shape are built up of numerous s i l t / c l a y flakes, generally some centimetres in diameter, rarely also up to 25 cm in size, and contain various fragments of vertebrate bones ranging in size from tiny splinters to larger pieces, and sometimes also fragments of partially slightly coaliferous plant stems. The silt/clay flakes are predominantly red violet or dark red, sometimes also bluish violet and pale greyish-violet in colour. Bedding plane features of substratum sandstones include minor linear erosional channels (up to 30 cm wide and 20 cm deep), isolated scour holes of ellipsoidal or irregular shape (up to 40 cm wide and 30 cm deep), small-scale flute casts (Plate I-8) of mainly simple ellipsoidal moldic, sometimes also corkscrew-like shape, isolated to abundant mouths of invertebrate burrows, primary current lineation, various tool marks, trains of flat current ripples with straight or linguoid crests, wave ripples, interference ripples with superimposition of wave ripples or secondary current ripples on primary current ripples, and fillings of desiccation cracks (diameter of polygons up to 30 cm). In several layers of greyish-violet or greyish-red mica-rich sandstones and siltstones/claystones, larger plant fragments up to 4 × 10 cm in size occur either as red-brown imprints on bedding planes or in weakly coaliferous preservations of compacted stems. In some evenly a n d / o r wavy horizontal-laminated sandstones, thin massive layers up to 5 cm thick are split into isolated balls and pillows of 10-15 cm width spaced 10-30 cm apart (cf. Plate I-7). The long axes of the balls are partially rotated with respect to the horizontal extension of the pillow layer which is aligned parallel to the bedding planes. At the lower contacts of the balls with the host sediment and around the pillows, occasional brecciated textures and deformation phenomena occur.

14 Fine member. The topstratum deposits consist mainly of fine-grained, dark red to red

violet, platy to papery, micaceous sandstones and siltstones/claystones. The sandstones are small-scale cross-stratified, horizontal-bedded or ripple cross-laminated. The overbank sediments are generally undisturbed or only weakly bioturbated and are only in some cases moderately to intensely burrowed. The fine member varies in thickness between several centimetres and ca. 2 m and ranges most commonly between some decimetres and ca. 1 m. The internal organization of the topstratum sequences is highly variable and includes thick horizontalbedded a n d / o r ripple cross-laminated sandstones with thin silty-clayey drapes at the top, silt/clay sequences with random intercalations of horizontal-bedded or crossstratified sandstones of lenticular or sheet-like geometry, alternating sand and s i l t / c l a y layers with laminae varying in thickness between some m m to several cm, and composition of microcycles consisting of 10-20 cm fine-grained sandstones and 5-15 cm silt/clay. Many overbank successions exhibit an internal fining-upwards trend with decreasing thickness and abundance of sand layers and diminishing thickness of microcycles. Some fine members are of multiphase origin and consist of several successive microcycles, whereas others are of uniform composition. Thicker sandstones, which are intercalated into silty-clayey successions or alternating sandy/silty-clayey sequences, have mainly even or gently wavy to undulating bases; sometimes, however, the sandstones cut into the underlying sediments with irregular erosional surfaces exhibiting relief of up to 20 cm. The sandstones are mainly transverse cross-stratified or horizontal laminated. Occasionally, low-angle heterolithic longitudinal epsilon-cross-bedded sets occur which are internally ripple cross-laminated or horizontal-stratified parallel to the master bedding surfaces. The longitudinal cross-stratification occurs as isolated sets or cosets built up of several overlapping units. At the top of the fine member, the sediments sometimes exhibit various blue-violet streaks and are partially destratified. Carbonate concretions, root tubes and more extensive blue-violet colours, however, have not been observed. The dominantly sandy Plattensandstein Formation is overlain by the R r t t o n e sequence (cf. Plate 1-4) which consists mainly of dark red to intense purple red or red violet, generally moderately to highly bioturbated siltstones/claystones. According to the intense burrowing, the primary horizontal lamination is in many cases only faintly preserved, and the sediments often exhibit a blocky texture. The siltstones/claystones frequently contain minor to moderate amounts of dispersed fine sand. Within the silty-clayey sequence, one laterally impersistent horizon of small-scale greenish root tubes has been observed (Ortlam, 1970, 1974, has described a better developed palaeosol from the R/Sttone in the Black Forest). The lower part of the R r t t o n e succession consists nearly exclusively of siltstones/ claystones with only isolated intercalations of thin sandstones. In the upper part of the sequence, several thicker sandstones occur which are horizontal-laminated,

Rrttone.

15 low-angle transverse cross-stratified or ripple cross-laminated and often contain thin layers of silt/clay flat pebble conglomerates at the base. Bedding planes of the sandstones are often densely covered with invertebrate burrows.

Interpretation The Plattensandstein Formation in Bavaria is deposited in a fluvial environment, as mainly evidenced by composition and organization of cyclothems, occurrence of carbonate breccias testifying to reworking of calcrete palaeosols which had formed in the alluvial plain, and presence of fragments of plant stems and vertebrate bones documenting vegetated overbank areas inhabited by reptiles and amphibians. The fluvial origin is especially indicated by comparative sedimentological interpretation of the Plattensandstein with the similar Kyllburg-Schichten sequence in the Eifel which is integrated into an alluvial succession reflecting the evolution of a fluvial depositional milieu through time (Mader, 1983b). The overall sedimentary environment of the Plattensandstein is a coastal alluvial plain at the margin of the prograding R6t Sea.

Coarse member. The Plattensandstein Formation is laid down in a moderately braided river systems consisting of low- to medium-sinuosity channels with narrow to moderate spacing of watercourses. The coarse member is partially deposited in a lower-flow regime as transverse channel bars and dunes which migrated downstream during aggradation of the streams. Abundant upper flow regime conditions of varying persistence result in frequent formation of plane beds which build up either thick successions as a consequence of longer periods of high-energy flow or occur as layers alternating with cross-stratified sets reflecting rhythmic to intermittent fluctuations or cyclic variations in flow regime. Decreasing water depth and diminishing or increasing current velocity in the course of continuous or discontinuous in filling of the channels lead to superimposition of successively smaller transverse bars and dunes a n d / o r passage from transverse forms to plane beds or vice versa. Some longitudinal sets at the top of channel sediment sequences (cf. Plate I-5) record occasional lateral accretions on flanks of transverse bars or in interbar depressions in the advanced stage of watercourse aggradation. Angular lower contacts of m a n y foresets testify to low backflow activity a n d / o r low clay content (cf. Turner, 1975a; Johnsen, 1981) being insufficient to create tangential contacts (as is also emphasized by the absence of backflow structures). The infilling of the alluvial channels is rarely continuous. The rapidly changing, unsteady and discontinuous flow regime is evidenced by numerous stage fluctuations of minor and intermediate magnitude (which have been reported from fluvial systems throughout geological history since the Precambrian; Banks, 1973). Episodically, falling water results in draping of foreset planes of arrested transverse bars with thin mud layers by settling of suspension fines or formation of current ripple

16 trains by low-stage reworking of foreset planes. The occasional intermittent and non-repetitive interruption of the downstream migration of the bars is documented by mud drapes and ripple trains covering only isolated foreset laminae (in contrast to rhythmical bundles in subtidal sand waves; cf. Visser, 1980; Visser and Mawbray, 1983; Mowbray and Visser, 1982; Teyssen, 1983, 1984; Allen and Homewood, 1984). Reset of high-energy conditions during the following flood stage often leads to formation of re~ictivation surfaces generating an intraset fabric. Alternating high and low water levels results in microcyclic composition of channel bar sequences by repeated intercalation of mud drapes covering the floor of the watercourse and the flanks of transverse bars under low discharge rates and weak transport capacity conditions during the low stage. Rapidly falling water level is reflected by abrupt change from sandy bar deposits to silty-clayey mud drapes, whereas continuously declining energy during slowly diminishing discharge results in the origin of fining-upwards waning-flow sequences consisting of fine-grained sandstones, silty-clayey sandstones and siltstones/claystones. The mud drapes on horizontal bedding planes between successive cross-stratification sets or on isolated foreset laminae testify to partially considerably episodic sedimentation during oligophase to polygenetic channel aggradation. Declining current velocities at the floor of the channels also give rise to settling of the sediments at the bottom of the watercourse by burrowing invertebrates, with the bioturbated surfaces in substratum sandstones documenting phases of possibilities of channel floor colonization. Alternating high-energy periods and slack water phases are also indicated by mica drapes on upper plane bed surfaces. Low-energy lower-flow regime conditions during the falling stage often gives rise to formation of current ripple trains on the channel floor, and strong winds blowing over tracts of gently flowing water sometimes generate wave ripples superimposed on large bedforms or interfering with current ripples. Minor stage fluctuations occur only occasionally in the early phases of channel infilling, but increase in abundance in the advanced and terminal periods of watercourse aggradation. Rapidly alternating low and high water levels in the final phase of substratum deposition sometimes result in the formation of heterolithic longitudinal cross-stratification sets. Intermediate stage fluctuations generally take place up to several times during channel infilling and give rise to multiphase watercourse aggradation. Rapidly alternating low- and high-energy sand deposition on the channel floor sometimes results in quicksand deformation as a consequence of inhibited dewatering prior to loading or plastic behaviour of silty-clayey, finer-grained sandstones. Liquefaction of the substratum leads to down-sinking of coarser layers as isolated pillows into finer-grained sandstones (cf. Plate I-7), accompanied by deformation or even destruction of the lamination in the surrounding sediments. Fine member.

In the narrow to moderately wide floodplains between the channels,

17 fine-grained sandstones are laid down in shallow minor drainage courses and sheet-like water bodies in low-energy lower-flow regimes, and silty-clayey sediments settled in quiet water in little ponds and larger lakes. High-energy floods often result in overspilling of the channel margins and lead to deposition of sand in moderate to broad belts of the levee zone. Channelized breaching of the banks gives rise to origin of mainly low- to moderate-sinuosity crevasse-splay watercourses which aggrade by migration of bars and dunes, rarely also to high-sinuosity overbank drainage courses which are infilled by lateral accretion under fluctuating energy conditions creating heterolithic longitudinal sets. Internal fining-upwards trends within the fine member record continuously declining current energy with decreasing influx of the main channel during passage from the proximal overbank area to the distal floodplain. Microcyclic composition documents repeated high-energy flood events which caused transport of considerable amounts of bed-load material into the overbank plain. Slow waning of the floods results in formation of successively lower energy sediments, whereas rapid declining of the floods favours abrupt draping of sandy current-generated deposits by quietwater muds. Continuous fluctuations of transport energy with rapidly and frequently alternating flowing and standing water lead to formation of interbedded sandy and silty-clayey topstratum deposits. During periods of declining bed-load deposition and suspension-load fallout, parts of the floodplains are colonized by burrowing invertebrates, resulting in bioturbation of the fine-grained overbank sediments. In some fine members, upwards-increasing organic reworking records continuous amelioration of settling as a consequence of progressively diminishing depositional rates. The absence of bioturbation in many fine members, however, may document that sedimentation is often considerably effective in preventing colonization of the bottom of the water bodies on the topstratum area. Emergence of parts of the overbank plain with efflux of flood waters and shrinkage of lakes and ponds finally results in pedogenesis and plant growth on the desiccated topstratum sediments. Formation of caliches with partially considerable amounts of carbonate concretions within the soil by illuviation testifies to a predominantly semi-arid climate during deposition. The vegetated regions were inhabited by reptiles and amphibians that moved through the overbank areas.

Composition of the sequence. Cyclothems recording burial of the infilled and abandoned channels by aggrading overbank plains are almost completely preserved only in parts of the Plattensandstein sequence. Strong erosion during rapid to moderate shifting of the narrowly to intermediately spaced watercourses often results in considerable erosion of top-stratum fines and especially palaeosols, thus giving rise to stacking of the substratum sequences of successive cyclothems to thick complexes of multistorey channel deposits. The reworked silty-clayey floodplain sediments are frequently redeposited as intraformational mud-flake conglomerates at the base of

18 the following coarse member. In some parts of the sequence, quiet-water overbank sedimentation is only documented by allochthonous fragments within channel sands. Throughout the succession, only the repeatedly occurring Br6ckelb~nke carbonate breccias (cf. Plate I-6) testify to advanced stages of soil formation in parts of the floodplains or emerged portions of abandoned channels, thus documenting subaerial overprinting of the alluvial sediments by pedogenesis. The caliche palaeosols of moderate to high maturity are only occasionally cut down to the lowermost parts of the B horizon, resulting in preservation of thin autochthonous remnants of initial pedogenic conversion in the stratigraphic record, but are in most cases completely reworked. Comparative sedimentological interpretation of the BrOckelb~nke within various fluvial successions rules out their lithogenetic significance as indicators of an alluvial depositional environment with alternating subaquatical and subaerial milieu (cf. Mader, 1984a, b). The abundance of intraformational conglomerates consisting of reworked silt/clay flat pebbles and the occurrence of BrOckelb~nke carbonate breccias (cf. Plate I-6) testify to the predominance of secondary-erosional removal as a mechanism of generating multistorey substratum sediment successions, with primary non-deposition being only of subordinate importance for stacking of channel sediment sequences in parts of the Plattensandstein Formation (the two main mechanisms controlling accumulation and preservation of the sedimentary record are discussed in detail by Mader, 1984d, 1985a). Vertebrate bones and plant fragments on bedding planes of both sandstones and intraformational conglomerates represent thanatocoenoses reflecting subaerial life in the alluvial plain. In other parts of the Plattensandstein succession, cyclothems consisting of substratum deposits and topstratum sediments ideally document polyphase channel infilling by several flood events separated by waning energy periods. Continuous shallowing during aggradation of the watercourses favours increasing abundance and effectiveness of stage fluctuations. Abandonment of the channels in the final phase of infilling and lateral shifting of the alluvial subenvironments results in burial of the aggraded watercourses by successively sandy proximal floodplain sediments and silty-clayey distal overbank deposits. Thick sequences of top-stratum sediments testify to longer stability of the overbank areas and sometimes deposition during several floods, whereas thinner fine members record shorter periods of floodplain aggradation as a consequence of shifting of the channels. Continuous passage from coarse member to fine member in many cyclothems by successively fining grain size and decreasing bedform height testifies to slow decline of current velocity with aggradation of the channels, resulting in transition in energy conditions from watercourses via levees to more distal parts of the flood plain. On the other hand, abrupt changes from substratum deposits to topstratum sediments in other parts of the sequence evidence rather sudden waning of transport capacity in the terminal stage of stream aggradation and weak capacity of flood waters entering

19 the overbank plain, leading to rapidly declining flow velocity away from the watercourse. The majority of channels are filled with homogeneous sand sequences which reflect continuous aggradation with only minor interruptions by short lowwater events between flood phases of short periodicity. Other watercourses, however, are filled with alternating sandy and silty-clayey deposits, testifying to frequent stage fluctuations with alternating low- and high-water stages in the course of floods of shorter duration and higher periodicity, or documenting abandonment of the channel from the main stream system and infilling by intermittent high-energy incursions alternating with periods of quiet-water suspension settling. ROttone. At the top of the Plattensandstein sequence, the passage into the R6ttone

succession (cf. Plate I-4) reflects rather rapid drowning of the coastal alluvial plain by a supratidal to intertidal mud flat. Considerable waning of both external continental influx and internal energy of deposition leads to passage from mainly aggradation of sandy watercourses and sandy/silty-clayey overbank areas to vertical accretion of extensive floodplains which are only in parts of the sequence occasionally intersected by widely to very widely spaced channels. Low rates of suspension fallout often allows continuous settling of the large flats with burrowing invertebrates. Bioturbation generally keeps pace with deposition thus resulting in complete organic reworking of thick silty-clayey sequences. The original lamination of the fine-grained deposits is generally completely destroyed, and the sandy material of isolated thin intercalations is homogeneously dispersed within the silty-clayey matrix by the moderate to strong bioturbation. Aggradation of the mud flat in the lower part of the sequence is only once interrupted by a last period of more extensive emergence, resulting in formation of a root tube horizon recording plant growth in partially desiccated regions of the floodplain. The subaerial overprinting, however, is too short to allow more intense pedogenic conversion of the muddy sediments to take place. In the upper part of the succession, sandy watercourses repeatedly cut through the mud flat and are infilled by sand waves, dunes, plane beds and current ripple trains, and sheetflood sands are spread out in parts of the mud plain. Increasing marine conditions and vanishing continental influx finally result in termination of Buntsandstein clastic deposition and passage to the Muschelkalk shallow-water carbonate sedimentation. Further formations in the Mid-European Buntsandstein which in terms of sedimentology strongly resemble both the Eifel Kyllburg-Schichten and the Bavarian Plattensandstein are the Solling-Sandstein in the Solling (Southern Lower Saxony and Northern Hessen as well as surrounding areas; cf. Herrmann and Hofrichter, 1962, 1963; Backhaus, 1968; Haubold and Puff, 1976; Puff, 1976; Ochmann, 1984) and the Labyrinthodont Beds in the Holy Cross M o u n t a i n s / P o l a n d (cf. Ptaszinski et al., 1984). Other comparable formations are parts of the Lower Triassic Moenkopi Group in Arizona, U.S.A. (cf. Blakey, 1974), the Permo-Carboniferous Supai Group of the Grand Canyon in Arizona, U.S.A. (cf. McKee, 1982) and parts of the Lower

20 Saxonian (Permian) in the Lodrve Basin in southern France (cf. Laversanne, 1976; Odin, 1982; Conrad and Odin, 1984). All these formations represent deposits of South Sasketchewan to Platte type rivers following the classification of Miall (1978).

DATA SAMPLING

The cross-stratification sets within the Eifel Kyllburg-Schichten and the Bavarian Plattensandstein have been measured in various outcrops of different size. All measurements were taken on two-dimensional exposures to obtain true foreset attitudes. In sandstones with platy cleavage, readings could often be taken immediately on the foreset plane. In edges of quarries or rock monuments, the bedding surfaces were constructed with two aluminium plates which then served as substrate for measuring, thus allowing mainly the direct obtainment of true dip directions rather than measurement of several apparent inclinations on two angularly oriented walls and subsequent interpolation within the stereonet. The data sampling was especially facilitated in the Eifel Buntsandstein by a suitable relationship between the joint pattern and the cross-stratification fabric (cf. Fig. 2 on p. 7). In this area, two main joint directions oriented perpendicular to each other are developed in most localities, with the palaeocurrent direction being either parallel to one of the joint bundles or extending in the mean of both joint directions. The narrowly spaced joints often created numerous edges in the outcrops allowing easy gathering of true dip directions of foreset planes. Most quarries expose only short sections (thickness between some metres and a few tens of metres) representing mainly sandstone complexes according to the exploitation of building stone. The uneven occurrence of the outcrops however, did not permit data collection on a grid pattern (similar conditions are frequently encountered in palaeocurrent studies; cf. K u m a r and Bhandari, 1973). All outcrops yielding at least some 10-15 readings were investigated as individual quarries. In some cases, several small local outcrops up to a few hundreds of metres distant from the neighbouring pit were summarized and treated as one quarry. Within the outcrops, all accessible cross-bedding sets have been sampled in a hierarchical rate aiming at an areal study of the palaeocurrent distribution. Where possible, measurements were spaced to give an approximately uniform sampling density along the outcrop. Every tabular cross-stratification set is generally represented by only one measurement (provided foreset attitudes are constant), whereas in trough cross-bedding sets often several readings were taken, accounting for the deviation of the current vector along the curved shape of the laminae. Wherever possible, measuring of trough axes (Meckel, 1967; Dott, 1973; Michelson and Dott, 1974; H o b d a y and Mathew, 1974; Slingerland, 1976) was preferred to exclude origin of bimodal data distributions by overweighting readings from the limbs of trough units. Planar cross-stratification sets were commonly measured in the direction of

21 m a x i m u m foreset inclination. Within composite sets, every intraset was sampled. The measurements deriving from mainly large- to medium-scale, occasionally also small-scale sets, were not weighted (cf. Miall, 1974) with respect to set magnitude (in contrast to Allen, 1966, Jackson, 1978, and Johnsen, 1981, increasing dispersion in current direction with decreasing bedform size has not been observed). The predominent amount of data was derived from medium- to large-scale sets ranging in thickness between ca. 20 cm and 1.5 m; small-scale sets measuring only a few centimetres and very large-scale sets exceeding 2 m have only rarely been sampled. In terms of set length (cf. Hoyt, 1971), most measurements were obtained from small- to medium-scale sets up to 6 m in length; subordinately, also large-scale sets exceeding 6 m in length were sampled. Small outcrops were dominantly treated as homogeneous in terms of data collection, but in various larger quarries, separate sampling was carried out for several parts of the exposed succession when lateral correlation and distinction of the units was possible. Correction of tectonic tilt was only necessary in a limited number of outcrops; in most cases, regional dips of the horizontal bedding planes and even diastems of only a few degrees did not require compensation. Collection of data at outcrop level excluded effects of palaeocurrent dispersion as a function of the sampling hierarchy (cf. discussion in Long and Young, 1978). Additionally to the abundant outcrops exposing mainly short sections, seven extensive sedimentary sequences of up to ca. 95 m thickness from the KyllburgSchichten of the Northern Trier area in the Eifel which are exposed in large quarries and rivulet gorges (for logs see Mader, 1979) have been studied, enabling analysis of the data gathered from these sequences in relation to stratigraphy. With logging of the sections for sedimentological interpretation, the vertically successive cross-stratification sets were sampled separately. Laterally persistent tabular sets are generally represented by only one reading, whereas within cosets composed of laterally overlapping trough cross-bedding sets, every individual set was measured. Erosional channels cutting into tabular cosets were treated as a separate unit. The seven very large outcrops were, in terms of data compilation, firstly considered as homogeneous or subdivided into several major portions for fitting into the areal palaeocurrent study, and secondly analyzed for variations of transport directions with time, aiming at a vertical investigation. Other palaeocurrent indicators such as primary current lineation, parting lineation, flute cast orientation, strike and asymmetry of current ripples and orientation of minor erosional channels and gutter casts (for diversity of unidirectional and bidirectional palaeocurrent indicators see Link, 1982, 1984, and Moore and Nilsen, 1984) could only rarely be measured. In most cases they revealed only two-dimensional strike data; these values have therefore not been incorporated into this study. Microscopic techniques such as applied by Allen (1964), Diessel (1966), Mehrabi (1978), Yagishita (1980) and Yagishita and Jopling (1983) or other methods to evaluate grain orientation (Shelton et al., 1974; Shelton and Mack, 1970) have not

22 been used. In the Middle Buntsandstein of the western Eifel, the palaeocurrent evidence from cross-bedding analysis at one locality could be supported by measurements of direction of downstream deformation by bending of autochthonously preserved Pleuromeia stems (Mader and Fuchs, in prep.). In total, 1459 measurements from 64 outcrops have been gathered from the Eifel Kyllburg-Schichten in the years 1975-1980, and 1852 data from 53 exposures have been collected from the Bavarian Plattensandstein in the years 1977-1978. The following outcrops are representative in terms of palaeocurrents: Eifel:

Fliessem Kyllburg Malbergweich

Bavaria:

Seffern Ebenheid Marktheidenfeld Wessental Wi~stenzell

Sheet 5905 44 800 Sheet 5905 45 750 Sheet 5905 46100 Sheet 5905 Sheet 6222 Sheet 6123 Sheet 6222 Sheet 6223

Kyllburg, r 39 800, h 44210 to r 38 620, h Kyllburg, r 43290, h 45320 to r 44260, h Kyllburg, r 39 450, h 45 640 to r 38 680, h Kyllburg, r 36170, h 48 180 Stadtprozelten, r 26 200, h 09 250 Marktheidenfeld, r 42 800, h 23 800 Stadtprozelten, r 29 520, h 09 250 Wertheim, r 47150, h 16100

DATA ANALYSIS Directional statistics

Cross-bedding measurements have often been presented by means of current roses or of polar points within the Schmidt net (for an overview of the conventional techniques including bibliography see Potter and Pettijohn, 1977). Emphasis is given below to methods allowing analytical mathematical computations according to the needs of statistical data treatment. Mathematically, a cross-bedding measurement is represented by a unit vector in three-dimensional space which can be described by azimuth and dip angle. There are three possible modes of analysis by using: (1) circular distributions; (2) spherical directional statistics; and (3) methods of eigenvalue and eigenvector analysis. These three concepts are briefly outlined as follows. Referring to the problem of the distribution of circular cross-bedding azimuth data, we consider, according to Mardia (1972) and Plummer and Leppard (1979), the wrapped normal distribution and the Von Mises distribution to have partly properties analogous to the linear normal distribution. Neither of these two distributions has all the desired attributes analogous to the normal distributions in the linear case, but all are represented in either of both (Mardia, 1972). Furthermore, each of the two distributions under consideration can be satisfactorily approximated by the other (Stephens, 1963; Mardia, 1972). The Von Mises distribution especially has

23

been regarded to be appropriate to cross-bedding azimuth data (Pincus, 1953; Plummer and Leppard, 1979). The density function of the Von Mises distribution can be expressed as:

f(O,

1 - - e k .... ~0-~,o) 21rI0(k)

go, k)

(1)

0 <0~< 2~r, k > 0 , 0 ~ < b t 0 < 2 ~ where

Io(k ) is

the modified Bessel function of the first kind and order zero, i.e.:

oo

lo(k)=

E l ~ ( ½ k ) 2r r=o r!2

/% is the mean direction, k the so-called concentration parameter, 0 is a random variable, which is Von Mises distributed if its density function has the form of eq. 1. The Von Mises distribution is unimodal and symmetrical about 0 =/%. It can be shown (Mardia, 1972) that the sample mean direction, 2, is the maximum likelihood estimate of the desired mean direction, g0. 2 itself is the solution of the equations X=R-cos~

andY=R.sinY

(2)

with: n

X= Ecosa,

n

and Y = E s i n a ,

i=1

(3)

i~l

R = ( X 2-4- y 2 ) 1 / 2

(4)

The a i are the azimuths of the n cross-bedding measurements, therefore X and Y are the direction cosines and R the magnitude of the sum of n unitvectors. It follows easily that 2 is the azimuth of a vector sum, the magnitude of which can be normalized as = ( R . 100)/n

(5)

equals ( 1 - S), S = circular variance, and is therefore directly related to the concentration parameter, k, which can also be used to characterize the shape of the distribution (Plummer and Leppard, 1979). R, however, seems to be a more straightforward parameter and can be nicely displayed in palaeocurrent maps as the length of an arrow (Figs. 5 and 11). According to Mardia (1972) measures of circular skewness, gl, and kurtosis, g2, can be derived as:

g l = R 2 . s i n ( m 2 - 2 ~ ) / S 3/2, and g 2 = [ R 2 . c o s ( m z - 2 Y ) - R 4 ] / S 2

(6)

24 R2 and m 2 are the solutions of: 1

R2.cosm2 =-

n

n

1

Y'~cos2(ai-£),

and

i=i

R2.sinm2=-

//

" Y'.sin2(ai-Y)

(7)

i=I

It follows directly from the properties of the Von Mises distribution that .~ calculated after eq. 2 is only then a maximum likelihood estimate of /t 0, if the sample is drawn from an unimodal distribution. In particular, ~ cannot directly be calculated if the sample, i.e. the set of cross-bedding azimuths of one measurement site, is clearly bimodal. Bi- or trimodal sample distributions have therefore to be split up into subsamples, which can be regarded as having been drawn from two or three superimposed unimodal distributions. The .x-values computed from these subsamples are then maximum likelihood estimates of the /a0-values of the unimodal distributions. The splitting up into subsamples and computation of the Z-values can be done in maximizing a likelihood function n

L = E f ( o t j , Ixi, k i )

for i = 1, m

(S)

j=l

n = n u m b e r of data, m = n u m b e r of unimodal subsamples (see Plummer and Leppard, 1979, for further details). The dip angle of the cross-bedding data can also be considered using spherical directional statistics rather than circular. According to Mardia (1972) the following descriptive measures m a y be used. The sums of direction cosines of azimuths a, and dip angles ¢Pi are: S~

~ c o s oti ' c O S 99i i=1 n

Y = ~ sin a i • cos q~i

(9)

i=l n

Z = Y'. s i n % i=1

Analogous to the circular case it is possible to derive measures of:

RS = ( X 2 + r ~ + Z2)1/2

(10)

RS= ( RS. lO0)/n The mean azimuth Y 2 = arctan-~

(11)

has a dip angle of Z = arcsin R---S

(12)

25 Y is still a maximum likelihood estimate of the true distribution mean ~o as can be concluded from the discussions for the circular case. Considering f we have to consider the properties of the distribution from which the sample has been taken. That is certainly not a Fisher distribution. The Fisher distribution (Fisher, 1953) is unimodal and centrosymmetrical and is an extension of the Von Mises distribution to the sphere. The true cross-bedding distribution on the other hand is a girdle distribution since dip angles cannot exceed values of about 40 o The distribution can best be characterized using a method proposed by Scheidegger (1965), considering a matrix A,.j of the cross products and of the quadrats of the sums of direction cosines (change to axis normal to cross-bed plane supposed):

A q=

X2 YX ZX

I

XY y2 ZY

XZ ] YZ Z2

(13)

Eigenvalues and eigenvectors of this matrix characterize the spherical distribution and are related to the moments of inertia of the distribution. The type of the distribution (uniform, Fisher, unimodal-bimodal, girdle, symmetric girdle) can be derived from the ratios of the eigenvalues (Mardia, 1972). The eigenvector corresponding to the largest eigenvalue is a good estimate of the mean of the distribution (Scheidegger, 1965; Koch and Link, 1971). Not only an azimuth but also a dip angle can be derived which is a better estimate of the dip of the distribution mean than which generally overestimates the mean dip (Teyssen and Vossmerb~umer, 1980). Advantages and disadvantages of the different concepts will be considered later.

Mode of data analysis All computational procedures used in this study are available in a set of Fortran IV programs which was developed at the IBM/370-168 of the computing center of Bonn university. Figure 3 elucidates the steps of the data analysis. Directional statistics described above are processed by the program CRB3. Plots of current roses and successive estimation of the parameters of directional subpopulations in the case of bi- and trimodal samples are carried out by the programs PLUM1 and P L U M 2 of Plummer and Leppard (1979). The seven extensive sequences from the Eifel Kyllburg-Schichten allowing collection of data in relation to stratigraphy (as recently was also investigated by Sengupta, 1974; Miall, 1976; Marshall, 1978; Fryberger, 1979; Marzolf, 1982; Link, 1982, 1984; Bhattacharyya and Lorenz, 1983; Lawrence, 1983; Nemec, 1983; Ballance, 1984; Moore and Nilsen, 1984; Peterson, 1984) have been analyzed with the aim of ordering palaeocurrent directions in time (comparably, a statistical appraisal of sedimentary successions by time-trend analysis of cycles has been carried out by Turner, 1975, and Thrivikramaji and Merriam, 1975; see also Vistelius, 1961). Within these sequences, considerable variations of palaeocurrent

26 Mode of data analysis

Data

Correction

I

set

l

of

tecton col tilt

Program [RB3 Computation of circu- J Lor and ~herica{

statistical measures of the enf re sampe

Program PLUMI I Prinfplof of a current rose P

r

~

j

r

o

m

PLUM2

f <"are a t i m e e ~ T i m e

17 y

e

s

~

Program RODAPLT P~ot of mops oT current directions

Computation of a cumulative current rose of oil sample s tes

L Program VCTR Vector trend analysis of directional data Fig. 3. Mode of data analysis.

ser~es and auto-/

I

27 directions with time can be observed. Analysis of the time series of directions has been performed with the program A U T O C R of Davis (1973), which has been designed for time series and autocorrelation analysis of linearly distributed data. Therefore a subroutine D A T C O R was used to change circularly distributed crossbedding data into positive and negative deviations about the vector mean Y. Thus the directional data are linearly distributed and can be treated as usual in time series analysis. Processing of the program A U T O C R includes smoothing of the time series of data using moving averages. Palaeocurrent maps can be plotted with the program R O D A P L T by Siegenthaler (1978). The length of palaeocurrent arrows has been chosen proportional to the magnitude of vector means RS. Finally, vector trend analysis of the directional data has been carried out using a modified version of the program V C T R of Fox (1967) allowing estimation of the regional distribution of directional parameters. Determination of a general, smoothed flow pattern using statistical methods was first performed by Pelletier (1958) applying moving averages, a method which provides quite good results (cf. Sturm, 1971). Although the method of vector trend analysis was already published by Fox (1967) enhancing the possibilities of application of trend surface studies in interpreting sedimentary environments (cf. Miller, 1956, and Miller and Kahn, 1962), it has not been used in the last fifteen years. Recently Shakesby (1981) pointed out the advantages of this method. The results of this study might further encourage sedimentologists to use vector trend analysis. PALAEOCURRENTS IN THE EIFEL KYLLBURG-SCHICHTEN The results of the statistical palaeocurrent data treatment allow an enhanced reconstruction of fluvial transport characteristics and, together with the facies of the alluvial rocks (Mader, 1981c, 1983b), an interpretation of the river pattern in the Eifel Upper Buntsandstein. Finally, they enable sedimentological comparison with the Bavarian U p p e r Buntsandstein. Bipolar directions and bimodal distributions of palaeocurrents Description Examination of current roses from the Northern Trier area indicates that although the majority of the patterns are unimodal, various sites (20 of 51) display bimodal distributions which generally are expected not to be common in fluvial environments (see also Selley, 1968; Long and Young, 1978) that are often characterized by unimodal patterns (Klein, 1967) of diverging or converging type. In m a n y cases, the bimodal distributions are composed of bipolar, mutually opposed modes rather than of obliquely to perpendicularly oriented parts (Selley, 1968). The bipolarities of the palaeocurrent distributions can, however, be explained by taking into account the results of directional statistics. The histogram of the normalized

28 vector m a g n i t u d e s of all m e a s u r e m e n t sites of the N o r t h e r n Trier area (Fig. 4a) d i s p l a y s a s u p e r p o s i t i o n of two subsets of directional d i s t r i b u t i o n s which might b y s e p a r a t e d b y a limit of abt. R S = 50%. A d d i t i o n a l evidence is given b y c o m p u t a t i o n of the p a r a m e t e r l Y - Q I with Q - a r i t h m e t i c m e a n of d i p angles (Figs. 4B a n d D). The significance of this p a r a m e t e r is that small values of lY - QI i n d i c a t e rather u n i f o r m d e p o s i t i o n in a high-energy flow regime (cf. Teyssen a n d Vossmerb&umer, 1980). T h e subset with a value of R S less than 50% m a t c h e s with a g o o d fit the set of m e a s u r e m e n t sites with b i m o d a l d i r e c t i o n a l distributions. S e p a r a t i o n of two subsets is further d e l i n e a t e d by p l o t t i n g circular skewness of the d i s t r i b u t i o n versus circular kurtosis (Fig. 5). A cluster of p o i n t s of nearly zero-values of skewness a n d kurtosis indicates fairly s y m m e t r i c a l , u n i m o d a l circular d i s t r i b u t i o n s . The cluster is encircled b y other p o i n t s with larger values of b o t h skewness a n d kurtosis.

I

II

.-,-,:i

30%

30%

20-

:.::::::!

E l f el

i)~!::i':l

Kyllburg-Schichten

.":':::1

N o r t h e r n Trier a r e a

. . . . ~r

20-

-." tq

v.>'.:l

10-

10-

0 0

A 10 20I

30 t,.0 50 60

II

70 80

90 100

I.

8

12

16

I

I

20

21. 28

32 36

t~0 /,,4 t,8 I?-01

I

~

'/

32

36

II

%

2o- ):i<::~<~')

20-

10........

C

0

..

: / :"

:.'::=. • ":'~2

:'".':'."'.".'..'.:

:

•"..'.''..2.2..'.'..J i::' ...:. • . . ' - ' . ' . ". . " . '. : ; . i , :

:~ll

i.i' : • .<:

" ''q :'" '" "'> ": (" ~' / : :";' '" : '> :' 0

0

10 20

30

t.O 50

60

70 80

90 100

0

t,,

8

12

16 20 2t., 28

~"]

t,,o kt,

I

t,8 I?-QI

Fig, 4. Histograms of normalized magnitude of vector means RS (A and C) and l) - QI (B and D), both displaying superimposition of two subsets I and II (A and B: northern Trier area in western Eifel, C and D: northern Bavaria)•

~o

g2

29

yo

-3 2

2 -2

0

-2

gl

,F~O 2 g2

0

I

°,

-'3

I

-2

i,t

°.

i

I

-1

"~.'-

-2

-3

Eifel Kyllburg-Schichten Northern Trier area

g2

M 0

F'~

r

-2

2

0

2 g2

I

-I

½

½

gl

°o

-3

Bavaria Plottensandstein

B Fig. 5. Plots of circular skewness gl vs. circular kurtosis g2 and marginal distributions of gl and g2 of the directional distributions (measures of gl and g2 after Mardia, 1972). Note the cluster of points around (0, 0) in A which represents fairly symmetrical, unimodal circular distributions. Piatykurtic distributions are more common than leptokurtic distributions. A: northern Trier area in Western Eifel; B: northern Bavaria.

30 55-

Eifel

--~

Kyllburg-Schichten Northern Trier area

2

----~ 100% 3 --~ 50%

t! ,2

~

f

f

0 40

30

1

2

3 krn

t~5

Fig. 6. Map of palaeocurrent directions from the northern Trier area in Western Eifel. 1 = Vectors with R~> 50%; 2 = vectors with R-'-S<50%; 3= length of arrows proportional to the magnitude of vector mean RS. Note that vectors 1 indicate the general flow pattern (Fig. 16).

T h e origin of the two subsets giving rise to p a r t i a l l y b i m o d a l d i s t r i b u t i o n s can b e e x p l a i n e d b y p o s t u l a t i n g two different d e p o s i t i o n a l processes. The c r o s s - b e d d i n g d e p o s i t s of subset I (cf. Fig. 4) m a y represent larger, m o r e c o n t i n u o u s flow in a h i g h - e n e r g y - r e g i m e of p r o b a b l y p e r e n n i a l type, whereas subset II m a y represent smaller, p a r t i a l l y e p i s o d i c flow of p r o b a b l y e p h e m e r a l t y p e with larger v a r i a b i l i t y in d i r e c t i o n a n d flow regime. T r a n s p o r t a n d s e d i m e n t a t i o n rates are c o n s i d e r e d to b e significantly smaller a n d m o r e d i s c o n t i n u o u s than d u r i n g d e p o s i t i o n of subset I. O n the m a p of p a l a e o c u r r e n t directions o f the n o r t h e r n Trier area (cf. Fig. 6), different arrows have b e e n d r a w n for d i s t r i b u t i o n s with vector sum m a g n i t u d e s larger a n d smaller t h a n 50%. T h e general p a t t e r n of t r a n s p o r t can b e recognized b y c o n s i d e r i n g only those directions derived f r o m d i s t r i b u t i o n s with R S > 50%. T h e o t h e r d i r e c t i o n a l d i s t r i b u t i o n s o n l y give rise to a m o r e or less r a n d o m l y circular d i s p e r s i o n (see Fig. 3). R e f e r r i n g to the analysis of the b i m o d a l d i r e c t i o n a l d i s t r i b u t i o n s (Fig. 7; p l o t t e d values are a p a r t of d a t a from Fig. 6), a b o u t half of the p a l a e o c u r r e n t directions

31

which have been computed with program P L U M 2 fit rather well into the general transport pattern (Figs. 6 and 14). The palaeocurrent directions resulting from analysis of the data from the smaller Oberbettingen area in the western Eifel (Fig. 10) reflect a rather straight pattern of transport directions. The current rose (Fig. 9) displays a fairly symmetrical, unimodal directional distribution with a regional mean azimuth to the northeast. Analysis of directional dispersion and vector magnitude prove that all measurement sites but one are characterized by small dispersion and large values of RS. Comparison of the different directional statistical means (Fig. 10) shows that the dip angle of the spherical vector sum overestimates the mean dip (cf. site 9 in Fig. 11). The relatively small directional dispersion of the data from the Oberbettingen area causes only little differences between the various means. Considering distributions with larger values of dispersion (as in the northern Trier area, cf. Fig. 11a), the 55,,

Eifel

1

~

Kyllburg-Schichten Northern Trier area

2

\\ .i/.,,/

IX

S \

\ 0

1

2

3 km

~0~ 30

\ 45

Fig. 7. Map of palaeocurrent directions from the northern Trier area in the western Eifel, considering only locatities displaying bimodal distributions. 1 = Arrows indicate subdirection of a locality that fits to the general flow pattern, 2: arrows indicate the other subdirection. Two adjacent arrows belong to one locality, with the offsprings of the arrows having been slightly shifted in palaeocurrent direction to outline the nature of the vectors.

0

m

~o-

2o-

10-

2o

~o

6O

$0

90

~0 __m.

30

20

I0-

0-

.

1A

60

o

o

'eo

1B

i

]

L

~,0 2 0 - 0 - 2 0

',

I

I

!-

xx - - -

o.o%~° ~

,

,

i

,

i

20 - 0 - 20

i

2B;

oo

.-~:

I

o%

p

i

o

I i

i r

O+ zo

2AI

,J;

~o

I

~

i

i

I

r

I

i

I

i

I

I

~0

r

I

¢

,'~ ~?/?/?. ~'/?

20

30-

.~0

50

60-

80

m 90-

,

~0

r

~Q

,

r

,

i

r

[

,

i

,

20

i

,

xx

~0

r

oo~-~---'-

',

i

I

i

J

,

1.0 I 0 - 0 -

3B

60

I

3A

i

i

I

I

:p

i

,

i

.

,

,

p

,

i

~0 2 0 - 0 .

i

i

i

I

i

i

r

I

,

*

i

20

x x x XxxxxxX~xxx ~

x~x x~Ooo

~°' 5 -"~"-'~

ooo¢: ~

i

i

i

,

i

,

5A

40

~

~o

:

20 -0. 20

5,B ,

--

,

:

&o

oog,,.°o~.% ,,

~oo ~2o i.i

60

-

80

, 1o() 12o

_

WwxxXXoooooooOOo X~xXx x ~ X °
=

~o

. . ~ ; ' "..~--:-_ . --=--

I

,

I

I

I

i

i

i

i

I

i

I

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~

4A

IF"

q

i

i

*'° ¢io 2 0 -o. 2o ~0 60 . .= .i . ,i.i.i

i

i

i

i

,

~o ~o ~o o* ~ 0 ¢o j ,~,i , ~ .i .i .

6060

F

E , L , I J I mJ = I , I i

~r

--

~

i

i

x

6o

&o

20

o* 21o ¢o

6B~o~ ~°~°°'°°°°°

O~oOo-.

~.~.

.>"

6A.~I

I

i

:

i

i

i

6o

7B 16o ~o

I

. . . . . .

--

20

o. 20

:

,._

¢o

, ,

OoO o o

x x o o ~ ,ooo

;~,,--

t

',,

T

'

~'. ^>_--

7A

i i r

i ¢

q

i i

i

-30

20

~0

0

10

-20

-30

-~0

- 50

-60

- 7O

-80

-9O

&0 _m

30

20

10

0

10

20

]o

~o

50

60

70

e0

m 90

?

SCHICHIEN

MALBERGWEICH-

SCHICHTEN

KYLLBURG

SCHICHTEN

MALBERGWEICH=

$CHICHTEN

KYLLBURG

33 Eifel Kyllburg -Schichten

la --

i

i

,

,

,

,

r

20

25

,

i

Y

3o

4Q

i

0

5

10

15

20

25

30

35

,

i

5

10 15

I

I

I

30

I

35 ~.0°

%

Bavaria Plattensandstein

30

10

5a 0

Fig. 9. Cumulative current roses (a) and histograms of dip angle (b). 1 = Northern Trier area (western Eifel), sites with unimodal directional distributions. 2 = Northern Trier area (western Eifel), data from the analyzed sedimentary sequences (cf. fig. 8). 3 = Northern Trier area (western Eifel), sites with bimodat directional distributions. 4 = Oberbettingen area (western Eifel), all sites. 5 = Northern Bavaria, all sites. o v e r e s t i m a t i o n o f d i p b y t h e v e c t o r s u m m e t h o d w o u l d b e s i g n i f i c a n t l y larger. T h e d i s t r i b u t i o n s f r o m sites 1, 2 a n d 4 (cf. Fig. 11) d i s p l a y a r e l a t i v e l y l a r g e s k e w n e s s v a l u e . T h e m e a n d e r i v e d f r o m t h e m e t h o d o f S c h e i d e g g e r (1965) is t h e o n l y one giving a correct estimation of the azimuth mean of those directional distributions. A l t h o u g h m o s t of the results of this study have b e e n derived using the directional m e a n s w h i c h are c o m m o n in c r o s s - b e d d i n g analysis (see also P o t t e r a n d

Fig. 8. Changes of fluvial palaeocurrent directions with time in seven sections from the Kyllburg-Schichten of the northern Trier area (western Eifel). Deviation from mean value (degree) versus length of logged section (meter). Deviation data were calculated with the program AUTOCR and plotted vs. stratigraphic position. A: Plot of the original data points connected by straight lines. B: Smoothing of the point sequences in A according to visual estimation and correlation of different positive and negative lobes between the sections (signatures A - L ) . For geographical position of the sections see insert map in lower right. The sinusoidal manner of changes of transport directions within a single sequence and the possibility to correlate specific lobes between different curves reflects a spatially continuous and time-concordant shifting of the alluvial channel systems. The localities of sections 1-7 are listed in Mader (1981c) and logs are figured in Mader (1979).

34 Pettijohn, 1977), emphasis should be given in future to the eigenvector method of Scheidegger (1965) which is also generally used in palaeomagnetic studies for calculation of the mean vector (Koch and Link, 1971). Interpretation

Evaluation of probable modes of origin of other directions by compilation of depositional models that explain palaeoflow divergences in fluvial systems (Table III) reveals several possibilities of formation of the Buntsandstein bipolarities. The models which are applicable for both bimodal directional distributions and subpopulations in directional statistics are briefly outlined as follows (the reconstruction of the flow pattern within the general depositional model is presented in Fig. 12). High palaeocurrent dispersion and bimodalities were formerly considered as related to high-sinuosity meandering rivers as a result of changing course or joining a main stream at diverse angles (Pelletier, 1958; Selley, 1968; Kelling, 1968; Sengupta, 1970, 1974; Picard and Andersen, 1975; Marshall, 1978; Golia and Stewart, 1984), but the use of palaeocurrent patterns and their variances to help distinguishing streams of varying sinuosity (Selley, 1965, 1968) or estimating channel sinuosity (High and Picard, 1974) is fraught with difficulties (Jackson, 1978; Collinson, 1978; Bluck, 1979), as the picture is extremely complex (Mia! 1, 1974, %-

I

- ~

2/

1 / Eife!

Kyllburg-Schichten

"-"-~100%:~ Oberbettingen area

-,.

sOO/o-'j /.,,

P

t

0 6% 4&

Ikm &7

Fig. 10. Map of palaeocurrent directions from the Oberbettingen area in Western Eifel. 1 = Vectors with RS> 50%; 2 = vectors with RS< 50%; 3 = length of arrows proportional to the magnitude of vector mean RS.

35 N

[

Eifel m

/ g

e

n

.

I

Fig. 11. Comparison of different statistical means, measurements of the Oberbettingen region. Crosses: circular vector mean azimuth and dip of the arithmetic mean of dip angles; triangles: azimuth and dip of the spherical vector mean; circles: azimuth and dip of mean derived from the eigenvector method after Scheidegger (1965). Note the overestimation of the spherical vector dip as a function of spherical dispersion, site 9 for example has a significantly greater dispersion than the other sites. The azimuth deviations of the eigenvector solutions from the sites 1, 2 and 4 are due to a particularly great circular skewness of these directional distributions. 1980). T h e p a l a e o c u r r e n t d i s p e r s i o n is m o r e c o m p l i c a t e d t h a n was once thought, with a m a j o r p o i n t being the general increase in d i r e c t i o n a l v a r i a n c e with decrease in p h y s i c a l scale of the current i n d i c a t o r s in m a n y systems (cf. Jackson, 1978). L o w - s i n u o s i t y b r a i d e d streams are able to p r o d u c e h i g h l y - d i s p e r s e d p a l a e o c u r r e n t s w i t h i n a short reach d u e to the t e n d e n c y of transverse b a r s to m i g r a t e at high angles to the d o w n s t r e a m t r e n d u n d e r c o n d i t i o n s of r e d u c e d flow (Smith, 1972; Bluck, 1974; Rust, 1975; Cant, 1978). T h e variabilities of the vector m e a n s record the shifting b a c k a n d forth of the b r a i d e d river belts in response to the alluviation of the g r a d u a l l y s u b s i d i n g b a s i n floor (see H u b e r t et al., 1978). F u r t h e r , c u r r e n t o r i e n t a t i o n p a t t e r n s v a r y with discharge a n d flow c h a r a c t e r a n d d o n o t necessarily c o r r e s p o n d with the overall river t r e n d (Schwartz, 1978). B i m o d a l p a l a e o c u r r e n t d i s t r i b u t i o n s in fluvial d e p o s i t s are also r e p o r t e d b y Ore (1964), K e l l i n g (1969), Picard a n d H i g h

36

T A B L E III

Compilation of depositional models and processes which give rise to origin of divergent, bimodal or bipolar palaeocurrents in fluvial environments and evaluation of their applicability [or e×planation of the Buntsandstein palaeocurrent bipolafities. Legend: + + = very probable (confirmed by evidence), + probable (confirmed by evidence), ( + ) = less probable (no evideneeing contradiction), - = not probable (no evidence, no contradiction), - - = not applicable (contradictory observations) DEPOSITIONAL MODELS FOR DIVERGENT OR BIMODAL PALAEOCURRENTS IN FLUVIAL SYSTEMS MODEL

REFERENCES

g th~lweg

patlefn

BUNTSANDSTEIN OBSERVATIONS

SCHUMM (198})

EVALUATION

c.onges af *,o~p

Su~ermmp

+

p~.ho(ly d,ve,0~n* 4

~da

+

+ ÷

on~ ~Im~lor or varying s~ze on0 emsc~rg~

KEELING Iig68), DABRqO & FERNANDEZ 0 g a o l

I B e t h ma,n channel a n e crevosse spl~y C h o ~ . l s~nds o:cu,

4 SfAVRAKI$ D980 L PAYNE & SCOTT (f982)

I CohdenSotmon o( epmsod,c or 0is(o~tmnuo~s H O W patterns

protesse$

I NAGII

I

), H~GH & P I C A R D {197~),L O N G Hi'Tel

{I)78]

d u r i n g f a l l i n g o, rising water

surloces ~ o n , n 9 drapes ~nd changing p

{1971), STEINMETZ(1972) )M Stogl y ~ d l c o t e d by Internal m u d dtQ I {1974k, NIJMAN ~ PUIGOEFABREGAS (19?B}, RAST el Q({19?6) I pe~ ~nd changes of gr~,n s,te end cross bed sol t~mckness

~I =Y s m ° l l h a n n a $ in QW WO ef sIoges and super,mpos,t,on o

MADER unpvbl modmfme~ f r o m CANT & WALKER (Ig?8l

I 5 m a l b to m e d i u m stole cross bed Sets ol lop of chan~el bat

I sequences w i t h d i l l ° r e n t o r i e n l o l , o n s Qfe prOS°hi

A l t e f n ~ h n 9 l o w discharge, f l o o d discharge a n d fothng

I I I

FloOd episodes indicated by w o n m g drQpes m m u l h p h o s e

the sedkmentohon cycqe~

~v,.Ce~S=on

Cur/e~l d velgences °S re~uqk%i'm~'eg~[°f t ° p ° g l ° p h l ond origin of riffle pook sequences orang the eOge of

COLEMAN (19691' SCHWARIZ (1998) FERGUSON&WER~ilT Y (1983}

IFtowsepotohonovecchonnelbOrsdurmngbo~lu(l d,scho,ge I Flow seporolmon On downstream ends of bars ~eor bends

P,~bQ~le

I DAVIES { 966 , / A y L O R et oq 197 ), p~CARO & HIGH ()9~31 HANSON pg801, SIEWART (19811, HILLER&STAVRAK)S(1982) I BRADEN [1950), WOODYER 0970) I~YLOR el el (1971)

I

g I po,nt bor~, benches and overbo#k oreos

AYLORe~ ~ ( 9 7 ~ - - {19~0l

WOODYER

978 'WOODYER el °

1979

MORGAN

ErrotlC at c h a n g i n g HOw d,rectlons Outing ~ n e or s e , e r o [ , p a r h o l l y fLuc~uahng flood stage~ CROSS H e w s along g tocol[y I counter to Ih~ l o i n river f l o w dqrechon O~On~ modm[meO lr~nsver~e DO,S

~lngt

bars d e r a i l i n g I Loteto( mlgrOtiO~O( ~ n ~ : chonnel

S E NME Z [ 9")2, g78), STANLEY & FAGERSIROM I 97~), I SCHWARTZ 1197B} W I L L + ~ S 11966], SMITH Img721, BLUCK (1916) IURNER {1977: I C A N I & W A L K E R (19781, RAMOS& FRIEND ll9821

I SCHWARTZ (19'78) ~OHNSEN (1981)

Akt~f~otmno If,ON o~d o b l i q u e to Sk~ec.~nne[ fi(hn9 H i g h I~)Ogl L o w -~to 9 FiLhng of ~ p r , = $ 1 o n $ o~ c~o~n=q f l o o r f r o m t w o ~l~=s ,g floaT, s

HOBDAY & MATHEW (1974), ALLEN I1983) OKOLO [1983] S M I I M {Ig?2) STAVR.~ K~S (Ige0) ~OT~ ( ~ 3 ) ALAM el ol (19B3)

Whmrlpool,ng at I , , b u l o r )

MADE R ( u n p u b ( ) ~romo~e s y s t e ~

.

.

.

.

TWO ( o n t e m p o r o n e o u 5 intethngermng fluvlOl syslems :Iorg,

V ,,verdi systems of p o l h O l l y dmffe

~ge},nq of

.

.

from

.

ALLEN 4

.

I D . . . .~,o

(+ I .

.

.

[+, [+ i

I P t ° b o b ~ e ' b u t n ° evidence f ° u ~ 0

[+ I

I Probob(e, bul ~o evidence f o u n d

I+

Probable, I

:+

ProbGbte,

{+

m Plobobl.,bu( no ev,~ence found

{+

ProbabLe, Probable, Probable, I Proboble~ Probable,

(+ (+ (+ ~+ I+

bu( but but bu~ I

no or,dance found no ~ i d e n c e f o u n d

no evidence f o u n d no ~ylde~c~ @aged

Prob~ble,m

TURNER11915,1g?'/), STEAR llg00), S~MON & BLUCK (19821 SCHRADER 9 8 3 , KEL INO&GEORGE 982

5 y s t e m a h ( vGr,etlon5 In cu,renl direction wMh b e d f o r m

J 8LUCK 0974] STEEL & A A S H E I M (1978)

.

.

.

.

.

.

.

.

19V5, STEEL 19?6)

NO evidence oufl

Lot¢,ol ,nput y

),n of the

S~no d~p

,9,*ud,nm b a , s ~u,,~g t9

[ B o c k f i O w sedkm~niOhon ,n the l o w e r ports of the @or°sets 9rang

-

-

.

-

Iobu~er

RUSt (Ig72L ~AWSON [IgB)), PIENKOWSK( 1 1 ~ I

No lon0,1~d,~o, bars developed ~ue io ~bsence of grovel

-

ALLEN 0 9 6 6 L JOHNSEN H9811

NO ~=g~q@m~onl Change

~ -

POWER {19611 H A N D e* o¢ (1969 L WE$SEL {lg69), S M b I H )9?0, t 9 7 2 ) , S t A V R A K I S ( 1 9 ~ 0 ) , H I L L E R & S I A V R A K I S I I g B 0 ) , MATHISEN ~ VONDRA {198J}

pos,hon

-

~ of inve~llg

I No at o n l y ~ i n o r 0lveIgence5 b e t w e ~ ] o t e d

{ 1 9 5 8 L KEEL+NO (1964] W I L L I A M S (1965), McGOWEN (~70), CAN1 & WA KER [Ig?6,1S78] IURNER(I9? No or onL? mmof diverge )9~011CANT (19781GEORGE DSlB)),LAWRENCE (tg83 L I slroh~mc~Imoh ()p~, WILLIAMS Ii983)

;:22'2t::'

)

[+]

KELUNG (19691,TURNER11977), CAMPBELLD9801, CASEY {1980], JOHNSON (19el) r KRAPEZ [1981]

[ JOHNSEN (19el) WILSON (197H, BLUCK (1980)

~IVeFO~CeS lh ( ( O ~

: ) :

11979),TUNBRIDGE(ISSl),WRIGH~{19e2)

o [ s t , , a m syslems in the a l l u v i a l pio,n O~e,lopp,ng gi.aI ~n~ long Hvet £yst,ms

C'O~i St'O~'~'CO)'O~ ( ~ p ~

+

.

i proboOle, bul no ev,dence foun~ I

TURNER( 9 ? 7 ) , A B R A H A M S E N (1979 L BEHRENSMEYER&IAUXE )~BZ )l GALLOWAY e{ o~ (1982i, SIMON & BLUCK q)982) MATHISEN &VONORA O9831 .

rent Slyle

Super,rnpos m / i e'e~ sou,ce o,eos

ProDob[e,l

t S M I [ H (19?0),TURNER (197?), SCHWARTZ 11971B+, LAWRENCE (1983) ASTIN {19BI), SCHWARTZ (1978), STEEL & IHOMPSON [ 1 9 B ] )

fkows m the tee of tongmtudmflGt ~nd tronsver ~e bars

I+I

Pr°P °b°ble ~ . . I Probable b~t no evidence foun~

(l@?e}

fIQls w,th,n (he

I, :

l p,eOoble, but no evidence to~ed

SMITH (1~72), HIGH & PICARD 119?&), M I A L L [19?&, 19~?), LONG ¢ y O U N G (1978)

I Oe0o~lt,on ,n i~t.,~o[ Channels GnU/or devloimon of tt0ws

'n~e¢

* +

e$ o v~ctot ~ e o n

I RUST (q9)8]

Olst,nct stages of channel flilby dive,g,

Cross f l o w stages

+ +

ipho$,Ze~ by abundant $(QCk,h9

Ip angles Q ~ ~ g n l t u I EwIstence o t Nr~t- ond second order chonne[s

I

QuenHy stocked u F

I B O E R S M A el ol (196B}, ANDREASEN et GI 119821

~ped or pr~served, u p p e r f l o w °n(Y represented by p l a n e bed~ No

rag,me

pros°hi

~ -

-

FERNANOE z ~ O A B R I O {19781

poo,ly ~ha.n~t,Ted ~ y ~ l ~

rge d l o g o n o l l y o,,e~,,d

SCHWARTZ (19?8~

bed~o,m, P,e.T,,o~,~ bosemenl ,, bu,le~ . . : . p ~ of ~.ry SELLEY I1965L C O U R E L el o((19?3), O U R A N D

b o s e ~ e n t ,~t,e~

~n o coosl~l alluvial ptoln

(197ei

PELLE E R (19581,KELL N G (19681, SELLEY ( 9 6 8 ) , I SENGUPTA (1970,19?4) L A D (1971], K U M A R & B H A N O A R I 1)973), S I E E L 79~?), A S H L E Y Z R E N W l C K (1983L ASHLEY (19831

~ non1~ ,n p~,ts of ~ J ~ , , ~ ¢

EThel

- -

Moll) y rmvlrs, p r o b a b l e h,gh s,nuo I s h y s t r e a m s o n l y o( I h e top of t h e succls$,ons N ° eVldence ° ( o n )

- -

37 (1970), K u m a r a n d B h a n d a r i (1973), H i g h a n d Picard (1974), F r i e n d a n d W i l l i a m s (1978) a n d L o n g a n d Y o u n g (1978). A c c o r d i n g to these convergences, d i s t i n c t i o n of b r a i d e d a n d m e a n d e r i n g channels is often not p o s s i b l e b y e v a l u a t i n g p a l a e o c u r r e n t s w i t h o u t s u p p o r t b y further s e d i m e n t o l o g i c a l evidence. Bimodalities resulting from analysis of long s e d i m e n t a r y sequences (which reflect changes of t r a n s p o r t directions with time in a sinusoidal m a n n e r , Fig. 8) are caused b y the d o m i n a n t l y t r a n s i t i o n a l m e a n d e r i n g - t h a l w e g - b r a i d e d c h a n n e l p a t t e r n of the whole fluvial system, b u t divergences within short sections originate on smaller scales within the alluvial network. T h e m o s t p r o b a b l e reasons for the origin of the p a l a e o c u r r e n t divergences in s h o r t s e d i m e n t a r y sequences are c o n s i d e r e d to be s u p e r i m p o s i t i o n of channels of v a r y i n g size a n d discharge a n d of different o r i e n t a t i o n (Nagtegaal, 1969; divergence of b r a i d e d channels, Minter, 1978) having shifted t h r o u g h time a n d space (see also H u b e r s t a n d H y d e , 1982) as well as of larger a n d smaller m a i n channels ( m a j o r a n d

V Fig. 12. Synopsis of palaeocurrent interpretation in the Eifel Kyllburg-Schichten (for discussion of transport patterns see Table III). Schematical facies and flow models, no scale. Upper left and upper right: enlargements from the main block diagram. Legend: 1 = deposits of larger channels with more continuous discharge of mainly perennial type; 2 = sediments of smaller watercourses with more episodic discharge of mainly ephemeral type; 3 = deposits in crevasse-splay channels entering the overbank area: 4 = sand bars within streams (only shown in enlargement sections); 5 = silty-clayey floodplain sediments: 6 = pedogenesis and plant growth.

,-]

t~

39 m i n o r watercourses, see also Kelling a n d G e o r g e , 1971; Blakey a n d G u b i t o s a , 1984) a n d crevasse-splay channels (Kelling, 1968, 1971; D a b r i o a n d F e r n a n d e z , 1980; Stavrakis, 1980; P a y n e a n d Scott, 1982) which m a y have entered the f l o o d p l a i n from different d i r e c t i o n s (often being o r i e n t e d o p p o s i t e l y or at high angles to the direction of the m a i n watercourses, see also Steel, 1977) f o r m i n g a crevassed levee zone s u r r o u n d i n g the m a i n channel, as evidenced b y the r e c o n s t r u c t i o n of the fluvial d e p o s i t i o n a l n e t w o r k ( M a d e r , 1981a; the channel n e t w o r k in relation to flow p a t t e r n is o u t l i n e d in Fig. 12). Bimodalities created b y s u p e r i m p o s i t i o n of different crevasse-splay channels are also r e p o r t e d by G e o r g e a n d Kelling (1982). C a n t a n d W a l k e r (1978) e m p h a s i z e channels oriented d i a g o n a l l y to the general river trend. O n a larger scale, s u p e r i m p o s i t i o n of streams of different o r i e n t a t i o n s (cf. also Kelling, 1969) is the m e c h a n i s m m a i n l y creating the p a l a e o c u r r e n t divergences. S u b s t r a t u m s e d i m e n t s from successive c y c l o t h e m s which were laid d o w n by p a l a e o f l o w s from different directions (as also r e p o r t e d b y Bridge, 1982) are often piled up to m u l t i s t o r e y bodies (the stacking m e c h a n i s m is highlighted by d o w n c u t ting of channels into o l d e r s e d i m e n t s a n d occurrence of r e w o r k e d clasts of silty-clayey a n d s a n d y d e p o s i t s f r o m the previous c y c l o t h e m within the scour fill; for c o m p a r a tive e x a m p l e s cf. Plate II; for d e t a i l e d discussion see M a d e r , 1985a). D e p o s i t s from d i s c o n t i n u o u s or e p i s o d i c flows are also c o n d e n s e d within short s e d i m e n t a r y sequences (see also N a g t e g a a l , 1969) b y stacking due to s e c o n d a r y removal of o v e r b a n k fines from the s t r a t i g r a p h i c record b y i n t r a f o r m a t i o n a l erosion, to a m i n o r a m o u n t also b y p r i m a r y suppression of f l o o d p l a i n d e p o s i t i o n as a consequence of r a p i d l y shifting watercourses. T h e same applies for c u r r e n t divergences originating b y local d e v i a t i o n of c u r r e n t systems within rivers, p e r h a p s a u g m e n t e d b y changes in s t r e a m p a t t e r n s d u r i n g rising or falling flood stages, with shifting of successive w a t e r c o u r s e s resulting in m u l t i s t o r e y i n g of s a n d b o d i e s thus c o n d e n s i n g the variability of flow d i r e c t i o n in the s e d i m e n t a r y record (High a n d Picard, 1974; Long, 1978). C o n d e n s a t i o n b y stacking therefore results in s u p e r i m p o s i t i o n of s e p a r a t e genetical units d i s p l a y i n g different p a l a e o c u r r e n t directions. T h e stacked s a n d s t o n e successions r e p r e s e n t b o t h m u l t i p h a s e sequences, which o r i g i n a t e d by r e p e a t e d l y i n t e r r u p t e d Stacking of individual fluvial substratum sand bodies to multistorey complexes is highlighted by downcutting of channels into older sediments (1, 2) and occurrence of reworked clasts of silty-clayey and sandy deposits from the previous cyclothem within the scour-fill (1). The steep-sided channels testify to cohesive substrates (humidhesion sensu Vortisch and LindstriSm, 1980, in damp condition) and to partially bed-load saturated slurry-type (cf. Monro, 1982) low-viscosity flows operating occasionally within some channels during peak discharge. Comparative examples from the Carboniferous and Jurassic of Northeast England. 1: Middle Jurassic Saltwick Formation. Diameter of figure ca. 4 m. Quarries north of Gallihowe and Rockcliff Fm. near Upton northeast of Loftus (Topographical map 1 : 50,000, Sheet 94 Whitby, r 73400. h 519950 to r 474750, h 519800). 2: Lower Carboniferous Fell Sandstone (cf. Monro, 1982). Diameter of figure ca. 8 m. Rocks Bowden Doors between Lyham Moor and Dancing Green Hill southeast of North Hazelrigg westsouthwest of Belford (Sheet 75 Berwick-upon-Tyne, r 406800, h 632900 to r 407100, h 632450).

40

aggradation of one channel, and multistorey complexes which formed by superimposition of uniphase or polygenetic substratum members of different cyclothems (the significance of primary-depositional restriction of formation and secondary-erosional removal of overbank fines for the alluvial architecture is discussed in detail in Mader, 1984c). Diverging palaeocurrent directions in successive storeys within stacked channel deposit complexes may assist in recognition of the different genetical units (Puigdefabregas and Vliet, 1978; Bridge and Diemer, 1983; Lawrence, 1983) in sequences with little variation in grain size and poorly developed stratification trends. Similar bipolar directions and bimodal distributions of palaeocurrents within fluvial sequences are recorded in the cross-stratification fabric of the Lower Triassic Solling-Sandstein in the Soiling (Southern Lower Saxony, F.R.G; Mader, unpubl.) and in the Middle Jurassic Saltwick Formation in Cleveland (Northeast England; Hemingway and Knox, 1973) and have therein also predominantly originated by vertical superimposition of different units by multistoreying. In both the Eifel Kyllburg-Schichten and the Bavarian Plattensandstein, the abundant stacking of channels to multistorey complexes often results in considerable obliteration of original size and extent of the watercourses by erosional removal of parts of the stream fillings. In parts of the Middle Buntsandstein in Upper Franconia, however, the channel sands are separated by thick overbank successions and are sometimes even seen to pinchout therein. This allows easier recognition of the existence of several channel sizes within the alluvial plain apart from palaeocurrent statistics and enables detailed reconstruction of the alterations of stream width and depth and the changing frequency and distribution of channel types during the evolution of the river systems. Bimodality of distributions of dip angles and RS-values, together with the bipolar directional distributions, indicate the existence of streams of different size and discharge operating simultaneously in the alluvial plain. Apart from considering stacking of main channel and crevasse-splay channel sediments, the depositional model of Allen and Matter (1982) and Galloway et al. (1982) with minor ephemeral streams connecting the main feeder channels or crossing the floodplains or interaxial areas between the large perennial rivers or fluvial axes could account for the origin of the bipolarities. Bimodal directional distributions could also have been caused by the existence of second-order channels apart from first-order channels (Rust, 1969, 1978) or the presence of two distinct channel sizes (Bridge, 1982) in the river system, as indicated by considerable differences in substratum sandstone thicknesses. Several distinct stages of channel fill by currents nearly perpendicular to each other (Fernandez and Dabrio, 1978) might account for some of the bipolarities, as indicated by erosional surfaces within stories and occasionally changing palaeocurrent directions within cyclothems. The probable origin of some divergences by cross-flow or reverse-flow during

41 Comparative example from the Wisla river south of Warsaw/Poland

© @

0D sO 7 3

7

i

N Fig. 13. Palaeocurrent divergences created by emergence of sand bars and flats during low water stages and subsequent dissection of the shoals by smaller watercourses running perpendicular to the general downstream direction. Superimposition of these different directions in the sedimentary record by accumulation of deposits during sand flat growth (Cant and Walker, 1978) results in considerable spread of palaeocurrents. Legend: l = large-scale cross-bed sets generated in the main channel; 2 = small-scale cross-bed sets formed in the minor watercourses dissecting the flats: 3 = current direction in the main channel; 4 = flow direction in the minor watercourses: 5 = emerged parts of sand bars and flats during low flow; 6 = depositional area during low stage. Example from the Wisla river south of Warsaw. Poland. Schematically, no scale. falling or rising water stages (Collinson, 1971; Steinmetz, 1972; Stanley a n d Fagerstrom, 1974; N i j m a n a n d Puigdefabregas, 1978; Rast a n d Sch~ifer, 1978; Haszeldine, 1981, 1983; Blakey a n d Gubitosa, 1984) is confirmed by the presence of occasional m u d drapes a n d systematic changes of cross-bed set thickness within single c h a n n e l deposits evidencing i n f r e q u e n t stage fluctuations. The origin of cross-flows has b e e n observed d u r i n g a low stage of the Leine river near H a n n o v e r in the s u m m e r of 1983 (artificially created by river m a n a g e m e n t ) with emerging gravel bars deflecting the currents in acute to n o r m a l angles from the general d o w n s t r e a m direction o n both flanks of the bars (cf. Plate I-9). Supposing s u p e r i m p o s i t i o n of s u b s t r a t u m sediments conserving these diverging flow directions within the stratigraphic record, deviations of palaeocurrent direction of up to 150 o can be reflected by successive cross-stratification sets (cf. Plate I-9). Cross flows a n d even c o u n t e r flows have also been observed in the a u t u m n of 1983 d u r i n g a (natural) low stage of the Wisla river near W a r s a w / P o l a n d (cf. Fig. 13) which braids by emergence of

42 shallow and extensive sand flats (see also Cant and Walker, 1978) and gravel bars. During shoaling, small watercourses running perpendicularly or obtusely to the main downstream direction cut through the sand flats both towards the middle of the stream and towards the levee zones (some of the small channels dissecting the sand flats may also have originated during flood stages; see Cant and Walker, 1978). Superimposition of small- to medium-scale cross-stratification sets which originated by migration of small transverse bars and current ripples on the floor of these watercourses (representing typical facies sequences of sand-flat growth; Cant and Walker, 1978) records opposed palaeocurrent directions at the top of medium- to large-scale cross-stratification sets composing the main channel bar (Fig. 13). The foresets reflecting the general downstream direction are in turn oriented almost perpendicularly to the flow directions in the minor watercourses dissecting the sand flats. Burial of these substratum sequences by overbank deposits containing crevasse-splay sands, which themselves also originated from minor channels running perpendicularly to obliquely to the main stream on the adjoining floodplain, introduces further cross- to counter-dipping palaeocurrent directions. Some bimodalities of smaller scale may have originated by filling of depressions on the channel floor from two sides (Dott, 1973), resulting in both downcurrent and upcurrent plunging of trough axes. Examples of such fillings have especially been observed in the Middle Buntsandstein Karlstal-Schichten of Western Eifel around Biersdorf, some 10 km west of Kyllburg. Similar depressions have been encountered on natural sand bars within recent channels during low stages (Hayes et al., 1969). No evidence could be found in the Buntsandstein sedimentary record for other possibilities of formation of palaeocurrent divergences (which could be expected to have been able to take place in the Buntsandstein braided river system), such as erratic and changing flow directions during one or several, partially fluctuating flood stages (Steinmetz, 1972, 1978; Stanley and Fagerstrom, 1974; Schwartz, 1978), cross-flows along lateral bars or bars moving locally counter to the main river flow direction (Williams, 1966; Thompson, 1970; Smith, 1972; Bluck, 1976; Turner, 1977; Cant and Walker, 1978; Ramos and Friend, 1982; Haszeldine, 1983), sweep of flood waters across the containing levee of the channel (Morgan, 1970), cross-channel bars developing into sand flats (Cant and Walker, 1978), cross-flows along and around abundant linguoid a n d / o r modified transverse bars (Smith, 1972; High and Picard, 1974; Miall, 1974, 1977; Long and Young, 1978; Bluck, 1980b; Haszeldine, 1981, 1983), lateral migration of bars and sandflats within the channel (Smith, 1970; Turner, 1977; Schwartz, 1978; Lawrence, 1983), cross flows in the lee of longitudinal and transverse bars (Schwartz, 1978; Astin, 1981; Steel and Thompson, 1983), thalweg diversion around developing longitudinal bars (Kerr, 1984), oblique flow across the bar surface (Levey, 1978; Schwartz, 1978; Haszeldine, 1981, 1983; Blakey and Gubitosa, 1984) deposition in interbar channels and deviation of flows around bars at low stage (Schwartz, 1978; Johnsen, 1981), alternating axial and oblique to side channel filling (Hobday and Mathew, 1974; Allen, 1983; Okolo, 1983; Golia

43 and Stewart, 1984) and high-stage (Smith, 1972) as well as low-stage bar modification (Stavrakis, 1980). Patterns produced by flood and falling discharge have high azimuthal dispersions in channels with wedge-shaped cross section and areas of low topographic relief, and low dispersion in areas where the channel is constricted or where a chute is formed during the flood (Schwartz, 1978). Highly variable current orientations in the sedimentary record originate by complex flow patterns within low discharge, flood discharge and falling discharge periods during course of the sedimentation cycles. At low stage, the irregular topography of the bars causes the flow to deviate greatly from the overall trend, with the flow patterns around channel bars causing high dispersion of orientation vectors. At high stage, increased flow depths reduce the effects of the topographic inconsistencies, and low dispersion bedforms are generated in response to high discharges (Schwartz, 1978). Bimodalities are generally not expressed by herring-bone cross-stratification (see Plates I-1 and I-2) which may form within channel sands near the confluence of two rivers by flow reversal during flood events depending upon discharge and stage in one channel relative to that in the adjacent watercourse, with the current directions being principally determined by water table surface gradients rather than by regional slope (Alam et al., 1983), by reverse flows by currents running into the channel from point bars, benches or overbank areas (Taylor et al., 1971; Woodyer, 1978; Woodyer et al., 1979), by reverse flows originating by separation on downstream ends of bars near river bends (cf. Braden, 1950; Woodyer, 1970; Woodyer et al., 1971), by whirlpooling at tributary mouths or confluences (whirlpooling effects on flow direction have been observed in parts of the Niagara river near St. Catherines, Ontario, Canada, in the summer of 1982; for location map see Friedman et al., 1982), by complex flow patterns at the extreme edge of the stream and flow separation over channel bars during bankfull discharge (Taylor et al., 1971; Leeder and Bridges, 1975; Nanson, 1980; Stewart, 1981; Hiller and Stavrakis, 1982) or may also originate in levee sands by overbank flow diversion from the channel (Turner, 1982). To a minor amount, however, herring-bone cross-stratification representing bipolarities in very short sequences (cf. Plates I-1 and I-2) occurs repeatedly within various fluvial sections of the Buntsandstein in Eifel, Bavaria (both Franconia and Oberpfalz), Solling and the Holy Cross Mountains (Poland) and is also reported from the Buntsandstein in Hessen (Wycisk, 1983, 1984) and Thuringia (Grumbt, 1974), testifying that probably episodic and random changes in water surface slopes (cf. Prestegaard, 1984) occasionally allow currents to reverse (Alam et al., 1983). Herring-bone cross-stratification has also been observed in fluvial parts of the Middle Jurassic Saltwick formation in Cleveland (Northeast England; see also Hemingway and Knox, 1973). Palaeocurrent directions sometimes change considerably from one cyclothem to another (see also Fig. 8), and multistoreying of channel sand bodies by erosion of overbank fines gives rise to stacking of cross-stratification sets which were formed by

44 partially divergent palaeoflows. Considerable divergences or even reversions in the orientation of successive large- to small-scale cross-stratification sets within fluvial sections are also described by Steinmetz (1975), Cant and Walker (1976), Cant (1978), Steel and Aasheim (1978), Schwartz (1978), Steinmetz (1978), Taylor et al. (1971), Rast and Sch~fer (1978), Woodyer et al. (1979), Allen and Matter (1982), Bridge (1982), Payne and Scott (1982), Bhattacharyya and Lorenz (1983), Dodd (1984), Turner and Whateley (1983), Ree (1983), T. Dec (pers. commun., 1983) and Turner (1983), and intercalations of reversely-dipping ripple cross-laminations within small-scale cross-stratification sequences (thus being in contrast to backflow structures, cf. Boersma et al., 1982; Fernandez and Dabrio, 1978; Fernandez, 1980; Andreasen et al., 1982; Nemec, 1983) are reported by Davies (1966), Taylor et al. (1971), Stewart (1981) and Hiller and Stavrakis (1982). Plint (1983) describes consistent palaeocurrent directions within individual bar sequences, but considerable divergences between successive storeys. Shelton and Noble (1974), Shelton et al. (1974) and Allen et al. (1982) describe considerable divergences of palaeocurrent directions derived from avalanche foresets and parting lineations. In contrast to the Buntsandstein bipolarities which result from interbedding of cross-stratification sets of different orientation within the sequence exposed in one outcrop (presence as intimately interbedded layers as well as occurrence at discrete levels), Steel and Aasheim (1978), Strack and Stapf (1980), Massari (1983), Wells (1983) and Johnson (1984) describe moderate to considerable lateral changes in palaeocurrent direction from one exposure to another, with the individual outcrops showing homogeneous unimodal distributions. Other depositional models for the origin of bimodal directional distributions in fluvial systems which have been reported in the literature (Table III) are not applicable to the Eifel Buntsandstein deposits because of lack of evidence or contradictory observations. These are especially independent interfluvial drainage systems (Allen and Williams, 1979; Tunbridge, 1981; Wright, 1982), two contemporaneous interfingering fluvial systems (one main system and one tributary system; Turner, 1977; Abrahamsen, 1979; Behrensmeyer and Tauxe, 1982; Galloway et al., 1982; Simon and Bluck, 1982; Mathisen and Vondra, 1983; Blakey and Gubitosa, 1983), confluence and mixing of two similar main alluvial systems (Turner, 1975a), two coalescing fluvial systems of partially different style (Kelling, 1969; Turner, 1977; Campbell, 1980; Casey, 1980; Johnson, 1981; Krapez, 1981), and superimposition of laterally shifted centripetal or centrifugal drainage systems with time (modified from Allen, 1981; cf. also Singh, 1984); no evidence, however, was found for the existence of sedimentary environments with different types of fluvial regimes in the Eifel Upper Buntsandstein. Superimposition of rivers coming from different source areas (Kelling, 1969; Turner, 1971; Stear, 1980; George, 1982; Simon and Bluck, 1982; Brady, 1984; Ewijk et al., 1984; Moore and Nilsen, 1984; Vinchon and Toutin-Morin, 1984; the provenance of fluvial material from two different source areas can be independently ascertained by radiometric dating of detrital minerals;

45 cf. Mitchell and Taka, 1984) is partially represented in the Middle Buntsandstein of Northern Eifel (Mader, 1983a, 1984c; see also Schrader, 1983) by regionally inhomogeneous gravel distribution, reflecting flows coming laterally from the western margin into the longitudinal Eifel depression. In the upper Buntsandstein, the marginal input of coarse gravel additionally to the longitudinal transport of sand and thus the interference zone of laterally inflowing and axially draining river systems, was restricted to the very western margin of the Eifel depression far beyond the western boundary of the investigation area (origin of perpendicular palaeocurrents by overlapping of lateral-marginal and longitudinal-axial fluvial transport is also described by Wilson, 1971, Steel and Wilson, 1975, Steel, 1976, and Bluck, 1980). According to the stable cratonic position of the Eifel area, a separation of two major fluvial systems by a zone of tectonic instability (George, 1982) or division of the basin into two parts with independent palaeocurrent directions by a major fault (Arche and Gomez, 1984) could not develop. Systematic variation in current direction with bedform, probably dependent on water depth and flow stage (Bluck, 1974; Steel and Aasheim, 1978) or highly variable directional nature of the trough cross-bedded sets (Mathisen and Vondra, 1983) with considerable divergences of transport direction recorded in different cross-stratification types (Pelletier, 1958; Kelling, 1964; Williams, 1966; McGowen and Garner, 1970; Cant and Walker, 1976, 1978; Turner, 1977, 1980; Cant, 1978; Haszeldine, 1981, 1983; George, 1982; Lawrence, 1983; Williams, 1983; Brady, 1984) seems not to be responsible for the origin of bipolarities, as considerable divergences in palaeocurrent directions between associated tabular and trough cross-bed sets have not been observed (as also reported from other formations by Meckel, 1967; Barrett, 1970; Sengupta, 1974; McLean and Jerzykiewicz, 1978; Legun and Rust, 1983; Hiller and Stavrakis, 1984; G o o d and Bryant, 1984). Cross- and counterdipping sets did not originate by deposition on flanks of longitudinal bars during falling stage (Rust, 1972; Dawson, 1983; Pienkowski, 1983), as only transverse bars were developed in the watercourses within the investigated Buntsandstein members. Antidune backset deposits originating mainly in the chute and pool stage of sediment transport by continuous upstream migration of an antidune in an aggrading channel (Gilbert, 1914) which have been described from Triassic fluvial sediments by Hand et al. (1969), Wessel (1969), Laversanne (1976), Stavrakis (1980) and Hiller and Stavrakis (1982, 1984), have not been recognized in the Eifel Buntsandstein, although abundant horizontal-stratified sets with parting lineating indicate numerous phases of upper-flow regime deposition. All the cross-stratification which has been observed is of lower-flow regime foreset type. It may be that either the conditions necessary for antidune formation never were reached in the channels, or that antidunes that had occasionally originated were not preserved in the sedimentary record. Fernandez and Dabrio (1978) attribute considerable dispersion of palaeocurrent directions to discontinuous flow with changing flow direction in poorly channelized

46 systems; the Eifel Buntsandstein watercourses, however, have evidently been channelized streams. The rivers are to be classified as channel-flow-dominated channels, thus in contrast to sheet-flow dominated channels with large diagonally oriented bedforms (Schwartz, 1978). Deviation of flows by the irregular topography of the basement relief (Selley, 1965; Courel et al., 1973; Durand, 1978) was for the main part only effective in the inferior parts of the Middle Buntsandstein covering the eroded Devonian basement and in the Upper Buntsandstein Kyllburg-Schichten was restricted to the surroundings of a few local elevations of the basement morphology not yet buried by the Buntsandstein sediments (similarly, Turner, 1977, finds practically no intrabasinal control of drainage patterns through local topographic features). Finally, there is no evidence for any tidal influence on the rivers (Gayer and Stead, 1971; Kumar and Bhandari, 1973; Steel, 1977; Watchorn, 1980; Ashley, 1983; Ashley and Renwick, 1983; Leo and Allen, 1984; Singh, 1984) with invasion of fluvial channels by marine waters (cf. Moore and Nilsen, 1984) in the investigated parts of the Buntsandstein sequence to account for some of the bipolar palaeocurrents. Tidal environments, however, are reported from stratigraphically younger Buntsandstein members (Gall, 1971) and from the Lower Muschelkalk (Schwarz, 1975), representing the end of the evolution of fluvial depositional milieu (Mader, 1983b, 1984a). The palaeogeographical situation of the Kyllburg-Schichten and subsequent Voltziensandstein, with the Muschelkalk sea gradually transgressing over the alluvial plain with time, would allow one to expect the occurrence of some tidal influence, which in Recent environments has been proved to be effective, even some 250 km upstream from the mouth of the Hudson River (G.M. Friedman, pers. commun., 1982). The abundance of divergent flows, their occurrence within fluvial cyclothems, the absence of marine fauna and the high-energy sedimentary structures, however, exclude any tidal influence giving rise to the formation of bipolar foresets.

Variability of transport directions through time and ooerall depositional model Regarding the nature of the major alluvial channels, it is important to note changes of transport directions with time in a sinusoidal manner (Fig. 8). The deviation curves of the different sequences seem to be linked together, and the boundary Malbergweich-Schichten-Kyllburg-Schichten is marked in all the sequences by a maximal negative directional deviation. The sinuous reaches between both negative and positive extremes of deviation values and the turn points of the meandering deviation curves could be connected from section to section (as outlined by different signatures in Fig. 8B), with minor loops occasionally intercalated into some sequences and missing in others (a similar correlation of smoothed curves is carried out by Turner, 1975). A similar correlation can also be made with mean palaeocurrent directions of short sections within the long sequences (Mader, 1981c), with the individual portions including one or a few cyclothems.

47 This subdivision of the Buntsandstein succession into units with comparable deviation of palaeocurrent direction gives evidence of the applicability of palaeoflow interpretations in stratigraphic analysis of continental formations, provided sufficient outcrop conditions (in short sequences, it is often either impossible to prove the existence of a significant autocorrelation reflecting an environment-related evolution of flow directions with time, or the smoothing procedure cutting off both tails of the section leaves only little remnants no longer displaying time trends; see also Turner, 1975b). The changes of transport directions with time in a sinusoidal manner result in changing mean palaeoflow for the successive units, but lead to a more or less constant general palaeocurrent direction for the whole sequence (a similarly consistent general palaeoflow direction both in time and space with only minor changes of local arrows is reported by Sengupta, 1974). This is in marked contrast to a significant gradual shift of the general transport direction as observed by Sengupta (1970) in Triassic fluvial sediments in India, a radical change in sediment provenance and transport direction as described by Brady (1984), a repeated turn and return of palaeocurrent directions with time as reported by Glazner and Loomis (1984) and Peterson (1984) and a large-scale reversal of drainage patterns with time by changing inclination of the palaeoslope due to tectonic movements as outlined by Miall (1984; see also Van Houten et al., 1984). The changes also rule out that the palaeocurrent directions in fluvial environments must not necessarily be more persistent than the palaeoflow directions in any other milieu (cf. H a r m s et al., 1963), but may vary considerably. A conformable environmental development of the alluvial channels obviously reflects a time-cyclic trend of sedimentation (Turner, 1975b). This is explained by spatially continuous and time-concordant shifting of the dominantly braided river channels fitting with the results of the sedimentological investigations (Mader, 1981a, b, 1983b), representing secular .variations in the current systems. Considerable changes in palaeocurrent directions with time are also reported by Abrahamsen (1979), Hiller and Stavrakis (1980), Turner and Whateley (1983); in contrast, Pelletier (1958), Meckel (1967), Sengupta (1970, 1974), Turner (1977, 1980, 1983), Lawrence (1983), Nemec (1983) and Moore and Nilsen (1984) describe generally consistent transport directions through time on large- or very large-scale. In contrast to the multiple cyclic shifting of palaeocurrent directions in the Eifel Buntsandstein, Hiller and Stavrakis (1980), Johnsen (1981) and Turner and Whateley (1983) find a continuous and progressive change of transport direction with time. Vector trend analysis reveals a rather uniform and stretched pattern of fluvial sediment transport (Fig. 16) thus also confirming the principally braided nature of the alluvial environment. The trend surface map (Fig. 16A) is a sum of a linear and a quadratic trend surface which provided the highest value of reduction. The map of unexplained residuals (Fig. 16C) indicates the quality of explanation of the data structure.

48

5555

---"

I

Bavaria

-->

2

Plattensandstein

---D- 100% --~. SOO/o

3

p

J

\

0

5

10 km

5473 3510 3562 Fig. 14. Map of palaeocurrent directions from northern Bavaria. 1: Vectors with R S > 50%; 2: vectors with R~< 50%; 3: length of vectors proportional to the magnitude of vector mean RS. Note that vectors 1 indicate the general flow pattern (cf. Fig. 17)

C o n s i d e r i n g the whole fluvial system, a transitional m e a n d e r i n g - t h a l w e g - b r a i d e d c h a n n e l p a t t e r n (type 4 of the classification of bed-load streams; Schumm, 1981) would p r o b a b l y best account for all palaeocurrent data (sedimentological processes a n d flow p a t t e r n s a n d their implication on the stratigraphic record are s u m m a r i z e d a n d illustrated in a depositional model, cf. Fig. 12). This type of river is characterized b y large alternate bars or p o i n t bars dissected by chutes. Thus it gives rise to a basically b r a i d e d pattern, b u t a more or less m e a n d e r i n g thalweg with slightly to

49

moderately sinuous loops (at least in some reaches) can be identified from palaeocurrents through time (Schumm, 1981). A similar pattern is best reflected by the sinusoidal manner of changes of transport directions with time (Fig. 8) in the Kyllburg-Schichten of the northern Trier area. Parts of the alluvial network that match low-sinuosity meandering streams or low- to medium-sinuosity braided rivers with occasionally intercalated meandering reaches are reported by Kelling (1971), Foster (1972), High and Picard (1974), Friend and Williams (1978) and Turner 5555-

Bovorio Plottensondstein --~

2

/ /

t

!

J/

0 5/,'/3 3510

5

10 km

3562

Fig. 15. Map of palaeocurrent directions from northern Bavaria, only considering localities displaying bimodal distributions. 1: Arrows indicate subdirection of a locality that fits to the general flow pattern. 2: arrows indicate the other subdirection. Two adjacent arrows belong to one locality, the offsprings of the arrows have been slightly shifted in palaeocurrent direction to outline the nature of the vectors.

50 (1982). Examples of generally meandering, but locally braided channels are described by Shelton and Noble (1974), Friend and Williams (1978), Marshall (1978) and Allen et al. (1982); other braided-to-meandering intermediate stream forms are reported by Rawlinson (1984); for further review concerning transitional river types see Mader (1983b). Schwartz (1978) reports a downstream change from braided to meandering river pattern over a distance of 230 km, with the central 100 km displaying a transitional stage. In the light of the longitudinal zonation of environments within the Mid-European Triassic Basin (Mader, 1984e), the Eifel North-South-zone, which extends some 100 km along the palaeocurrent direction, could well represent a comparable transitional part between the braided river belt in the Vosges, Pfalz and Saar areas and the more basinal milieus in the Lower Rhine and Ems areas. Within the braided-to-meandering transition, complex current orientation patterns develop depending on discharge and local topographic relief, resulting in highly variable azimuthal dispersions within the sedimentary record, with a great variability of current patterns probably being characteristic of this transitional river type (Schwartz, 1978). The uniform palaeocurrent distribution as reflected by the cross-stratification fabric of the Oberbettingen Kyllburg-Schichten may lead to the conclusion that the deposits of the Oberbettingen area (represented by the cross-stratification values) have been accumulated exclusively within major alluvial channels. It should be stressed, however, that firstly the Oberbettingen area is relatively small, and secondly the data were obtained from only short sedimentary sequences. As it is not reasonable to assume a major change in general palaeocurrent direction in an alluvial network within a distance of some tens of kilometres, the results from the Oberbettingen area are an excellent example to demonstrate that detailed reconstruction of fluvial style is only possible by analysis of at least some longer sedimentary sequences to test possible changes through time and to have a higher KYLLBURO-SCHICHTE~,, NORTHERN TRIER AREA. EIFEL / i ,,~ I .

.... \

, .

f

/

/

J

/

!

i "...~ •

f'

.

f B

! C

2~

Fig. 16. Results of vector trend surface analysis (data from the Northern Trier area in Western Eifel). A. Map of dip azimuths of the trend surface, sum of linear plus quadratic trend surface map (points indicate measurement sites). B. Interpretation of A with palaeocurrent vectors. C. Map of residuals of the trend surface analysis.

51 chance of getting access to more rarely preserved subenvironments; thus the outcrop conditions are the major limitations in the interpretation of alluvial milieus also in view of palaeotransport analysis. PALAEOCURRENTSIN THE BAVARIANPLATTENSANDSTEIN The Plattensandstein Formation in Northern Bavaria is comparable in many respects to the deposits of the Kyllburg-Schichten in the Eifel (northern Trier area). As the principles for interpreting the statistical results have already been explained in discussing the Eifel Kyllburg-Schichten, the features of the Bavarian Plattensandstein are not delineated in detail. Emphasis is given here to outlining the differences between the two formations which enable sedimentological comparison of both fluvial sequences. The maps of all palaeocurrent directions for the Eifel (Fig. 6) and Bavaria (Fig. 14) reveal comparable flow patterns which generally do not change if the subset lI (vectors with R S < 50%) are neglected. The plots only displaying localities showing bimodal distributions, however, reflect for Bavaria (Fig. 15) a predominance of north south reversing palaeocurrents and a general separation angle exceeding 150 o between the two subdirections, whereas in the Eifel (Fig. 7), west east reversing transport directions are of nearly equal importance as are north-south reversing flow directions, and the separation angle between the two subdirections does not always exceed 150 °, but often ranges between 90 ° and 150 °. The cumulative current roses (Fig. 9) also show quite similar distributions for Eifel and Bavaria, consisting of a predominant N W - S E sector and a subordinate S E - N W sector. The histograms of dip angles indicate maxima for both areas near 15 o, but reveal a greater importance of very low-angle dips in Bavaria than in the Eifel. The histograms of normalized magnitude of vector means R S and ] y - Qq (Fig. 4) display superimposition of subsets I and II for both the Eifel and northern Bavaria. The diagrams for I,~ - Q[ are quite similar for both areas. The graphs for RS, however, reveal a dominance of subset I in Bavaria, whereas in the Eifel, the two subsets appear to be of nearly equivalent importance. The plots of circular skewness gl vs. circular kurtosis g2 and the marginal distributions of gl and g2 of the directional distributions (Fig. 5) reflect for both areas similar maxima in skewness around zero. The maxima of kurtosis, however, are quite differently shaped; the histogram for the Eifel shows an acute peak around zero, whereas the graph for Bavaria displays a broad plateau. Vector trend surface analyses reveal some further differences between the Eifel (Fig. 16) and Bavaria (Fig. 17). The maps of azimuths of the trend surfaces (Figs. 16A and 17A) show for the Eifel a unidirectional increment with the azimuth isolines running parallel except for the northeastwards curving of the azimuth isolines, whereas for Bavaria, a bidirectional distribution results characterized by position of the lowest values in the centre of the map and an increment both to the SW and

52 N W , with the a z i m u t h isolines r u n n i n g parallel in each subset. T h e m a p s of p a l a e o c u r r e n t d i p a z i m u t h s as i n t e r p r e t e d f r o m the t r e n d surfaces (Figs. 16B a n d 17B) reflect g r a d u a l l y anticlockwise r o t a t i n g t r a n s p o r t directions in the Eifel from the western to the eastern part of the area, whereas in Bavaria, the directions turn anticlockwise at the southeastern m a r g i n a n d rotate clockwise at the n o r t h w e s t e r n m a r g i n of the region, with the directions r e m a i n i n g c o n s t a n t in the main p a r t of the area. COMPARISON OF THE EIFEL KYLLBURG-SCHICHTEN AND BAVARIAN PLATTENSANDSTEIN T h e results of the statistical c r o s s - b e d d i n g analysis of the Eifel K y l l b u r g - S c h i c h ten a n d the B a v a r i a n P l a t t e n s a n d s t e i n indicate quite c o m p a r a b l e fluvial d e p o s i t i o n a l c o n d i t i o n s d u r i n g parts of the U p p e r B u n t s a n d s t e i n b o t h at the western a n d the eastern m a r g i n s of the G e r m a n Basin. T h e most significant c o i n c i d e n c e is the occurrence of two subsets of directional d i s t r i b u t i o n s in b o t h sequences, e n a b l i n g m o r e d e t a i l e d r e c o n s t r u c t i o n of the alluvial n e t w o r k (Table III) than that b a s e d on s e d i m e n t a r y structures alone. T h e i n t e r p r e t a t i o n of the m a p s of dip a z i m u t h s of the trend surfaces (Figs. 16B a n d 17B) reveals rather u n i f o r m a n d stretched p a t t e r n s of fluvial s e d i m e n t t r a n s p o r t

PLArTENSANDSTEIN

, BAVARIA

Fig. 17. Results of vector trend surface analysis (data from Northern Bavaria). A. map of dip azimuths of the trend surface, sum of linear plus quadratic trend surface map (points indicate measurement sites). B. Interpretation of A with palaeocurrent vectors. C. Map of residuals of the trend surface analysis.

53 in dominantly moderately braided rivers for both formations. The differences in the palaeocurrent results between both sequences, however, point out that each fluvial environment was internally governed by independent factors. This applies especially to the network of the smaller watercourses interwoven with the main channel system. In Bavaria, the subordinate smaller flows are predominantly reversing, whereas in the Eifel, the minor channels are of greater importance and drain reverse as well as perpendicular to the main watercourses. The results of the vector trend surface analysis probably reveal the most interesting differences between the Eifel and Bavaria. In contrast to local palaeocurrents which originate from alluvial channels wandering on the depositional plain, the regional palaeocurrents interpreted from the map of dip azimuths of the trend surface reflect the palaeoslope. The consistent anticlockwise rotation of regional palaeocurrent directions in the Eifel may give evidence of a generally northwards-inclined depositional plain superimposed upon the eastwards-dipping western margin of the pre-Triassic depression zone, giving rise to a concave-upward curved shape of the basin surface in cross-section. The influence of superimposition of the more local radial-lateral palaeoslope on the regional longitudinal palaeoslope (see also Durand, 1978) decreases continuously from the western margin towards the axial part of the Eifel depression. The palaeocurrent rotation is therefore created by the general topography of the depositional plain which, although the pre-Triassic surface has already been nearly completely buried during the earlier Buntsandstein stages, still influences the sedimentary network, possibly kept effective by differential subsidence. The influence of the buried pre-Triassic morphology is, however, restricted to its large-scale topography, with minor local swells and inselbergs being ineffective in regional changes in palaeocurrent directions. The eastwards dipping component is also evidenced by the map of local palaeocurrents which show predominantly eastwards flowing main channels (Fig. 6) and a rarity of westwards-reversing minor watercourses (Fig. 7) at the western margin in comparison to the centre of the area. A steeper palaeoslope in the western part of the elongated Eifel depression than in the axial portion and near the eastern margin of the zone is also evidenced by the distribution of size and abundance of gravel within the Upper Buntsandstein fluvial sediments (Mader, 1984d). The changes of transport directions with time in a sinusoidal manner (Fig. 8) in the Eifel reflect stability of the palaeoslope throughout the investigated Upper Buntsandstein sequence, in contrast to abrupt changes in palaeoslope directions by tectonical uplift and tilting as evidenced by perpendicular general palaeocurrents within different parts of fluvial successions (Ross and Donaldson, 1982; Miall, 1984). Bavaria, however, in contrast to the marginal position of the Eifel, is situated farther off the basin boundaries, and the more continuous pattern of regional palaeocurrents reflects a generally northeastwards inclined palaeoslope which is undulated in the southwestern and the northeastern part of the investigation area.

54

GRAIN SIZE AND COMPOSITION OF THE EIFEL KYLLBURG-SCHICHTEN 2

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Fig. 18. Grain-size representation data for the Eifel Kyllburg-Schichten (Upper Buntsandstein, Lower Triassic). First row: grain-size curves plotted on probability and linear paper (mm or phi vs. weight percent). Black zone spans the range of all grain-size curves. Second row: textural and mineralogical composition in triangular representation. Black dot spans the extension of the point cluster. Third and fourth rows: grain-size parameters plotted as histograms.

55 The different positions of the two areas within the depositional basin, the broad plateau of the maximum of circular kurtosis (Fig. 5) and the greater importance of very low-angle dips (Fig. 9) in Bavaria compared with the Eifel may indicate a slightly steeper palaeoslope in the Eifel. The differences in palaeoslope resulting from the different palaeogeographical situations of the investigation areas, however, had only minor influence on the alluvial depositional environment. The basic principles of fluvial style of the Eifel Kyllburg-Schichten (Fig. 12) generally match those of the river regime of the Bavarian Plattensandstein, as evidenced by the predominantly similar results of the statistical palaeocurrent analysis. CONCLUSIONS (1) Statistical palaeocurrent data analysis allows more detailed reconstruction of the fluvial depositional environments in the Upper Buntsandstein (Lower Triassic) of the G e r m a n Basin than by sedimentary structures alone. (2) Bimodal palaeocurrent distributions with bipolar transport directions occur both within long and short sedimentary sequences in the Eifel Kyllburg-Schichten. (3) Bimodal palaeocurrent distributions within short sedimentary sequences reflect both larger, more continuous flow in high-energy regimes of probably perennial type and smaller, partially episodic flow of probably ephemeral type with larger variability in direction and flow-regime. (4) In contrast to a part of the bimodal palaeocurrent directions that fits rather well into the general transport pattern (although sometimes changing considerably from one cyclothem to another), many bipolarities originate primarily by superimposition of channels of different orientation as well as of main channels and crevasse-splay channels and by condensation of deposits from discontinuous or episodic flows. (5) The main mechanism creating the vertical succession of various directions is stacking of different substratum members to multistorey complexes by primary-depositional restriction of formation a n d / o r secondary-erosional removal of topstraturn sediments. (6) Bimodality of distributions of dip angles and R S values indicate the existence of streams of different size and discharge operating simultaneously in the alluvial plain. (7) The occasional occurrence of herring-bone cross-stratification representing bipolarities within very short sequences in the investigated formations, as well as in various other fluvial Buntsandstein successions, probably testify to episodic and random changes in water surface slopes a n d / o r various other mechanisms allowing currents sometimes to reverse locally. (8) Changes of transport directions with time in a sinusoidal manner, as reflected by the palaeocurrent distributions in long sedimentary sequences, indicate a conformable environmental development of the alluvial watercourses, reflecting a time-

56 cyclic trend of sedimentation. This is explained by spatially continuous and timeconcordant shifting of the channel system which is interpreted as a transitional meandering-thalweg-braided watercourse pattern. (9) The Bavarian Plattensandstein is largely comparable to the Eifel KyllburgSchichten in terms of palaeocurrent distribution and palaeoenvironmental interpretation. The main differences between both formations are outlined by vector trend surface analysis, reflecting bidirectional distribution and more complexly interfering anticlockwise and clockwise rotating patterns of dip azimuths of the trend surface for the Bavarian Plattensandstein. (10) The differences between Eifel Kyllburg-Schichten and Bavarian Plattensandstein point out that each fluvial environment was internally governed by independent factors which, however, had only minor influence on the general alluvial depositional milieu. (11) The orientation of the palaeoslope in the Eifel is characterized by superimposition of a more local radial-lateral palaeoslope on the regional longitudinal palaeoslope at the western margin of the depression zone. Bavaria, in contrast, reflects a unidirectionally inclined palaeoslope which is undulated in parts of the area. (12) In the light of predominantly similar results of the statistical palaeocurrent analysis, the basic principles of fluvial style at the western margin generally match those of the river regime at the eastern margin of the G e r m a n Basin during parts of the Upper Buntsandstein (Lower Triassic). ACKNOWLEDGEMENTS D M acknowledges supervision of his thesis (during the course of which most of the palaeocurrent data were gathered) by G. Fuchs (Karlsruhe) and W. Dachroth (Heidelberg), helpful advice concerning data sampling and conventional measurement treatment by M. Kirchmayer (Heidelberg) and financial assistance by a stipendium according to the Graduiertenf~Srderungsgesetz (GFG). He is also indebted to A. Barczuk (Warsaw) and G.V. Middleton (Hamilton, Ontario) for field guidance to recent alluvial systems from which ideas on palaeocurrent models emerged. Thanks are also due to P. Wycisk (Berlin) for information on opposing palaeocurrents in the Hessian Buntsandstein. The sedimentological interpretation of the Bavarian Plattensandstein was enhanced by impressions from comparative studies of similar formations first in the Mid-European Buntsandstein under field guidance by A. Barczuk and K. Rdzanek (both Warsaw) and D. Ortlam (Bremen), and second in other continental red bed formations, under field guidance by R.C. Blakey and L.T. Middleton (both Flagstaff/Arizona) with financial assistance by the Deutsche Forschungsgemeinschaft (DFG, Bonn) and by G. Conrad and B. Odin (both Marseille, France). The palaeocurrent model was further supported by comparative insight into the Middle Jurassic Saltwick Formation in Cleveland, England,

57

u n d e r field g u i d a n c e b y R. P e p p e r ( S a l t e r s g i l l ) a n d M . J . Y a r d l e y ( S o u t h B a n k ) a n d into the L o w e r C a r b o n i f e r o u s Fell S a n d s t o n e a n d the U p p e r C a r b o n i f e r o u s Coal M e a s u r e s in N o r t h u m b e r l a n d

under

field g u i d a n c e b y B.R. T u r n e r ( N e w c a s t l e -

u p o n - T y n e ) . K . A . W . C r o o k ( C a n b e r r a ) reviewed an earlier draft of the m a n u s c r i p t . a c k n o w l e d g e s H. V o s s m e r b a u m e r

a n d s t u d e n t s ( W i a r z b u r g ) f o r j o i n t field

w o r k in c o l l e c t i n g t h e c r o s s - b e d d i n g d a t a . H e is a l s o i n d e b t e d to A. Siehl ( B o n n ) f o r d i s c u s s i o n s o n d i r e c t i o n a l s t a t i s t i c s . T h a n k s are also d u e to C. S i e g e n t h a l e r a n d t h e Comparative

Sedimentology Division (Utrecht) for allowing application of the

unpublished program RODAPLT.

C a l c u l a t i o n s w e r e c a r r i e d o u t at t h e I B M / 3 7 0 - 1 6 8

of the C o m p u t i n g C e n t e r of B o n n University.

REFERENCES

Abrahamsen, K.A., 1979. Aspects of sedimentology and palaeogeography of the Lower New Red Sandstone (?Permian) of Arran, Western Scotland. Cand. Real. Thesis, Univ. Bergen, Bergen, 181 pp. Agterberg, F.P., Hills, L.V. and Trettin, H.P., 1967. Paleocurrent trend analysis of a delta in the Bjorre Formation (Lower Triassic) of Northwestern Melville Island, Arctic Archipelago. J. Sediment. Petrol., 37: 852-862. Alam, M.M., Crook, K.A.W. and Taylor, G., 1983. Fluvial herring-bone cross-stratification in a modern tributary mouth bar, Coonamble, New South Wales, Australia. In press. Allen, J.R.L., 1963a. Henry Clifton Sorby and the sedimentary structures of sands and sandstones in relation to flow conditions. Geol. Mijnbouw, 42:223 228. Allen, J.R.L., 1963b. The classification of cross-stratified units. With notes on their origin. Sedimentology, 2: 93-114. Allen, J.R.L., 1964. Primary current lineation in the Lower Old Red Sandstone (Devonian), Anglo-Welsh Basin. Sedimentology, 3: 98-108. Allen, J.R.L., 1966. On bedforms and paleocurrents. Sedimentology, 6: 153-190. Allen, J.R.L., 1967. Notes on some fundamentals of palaeocurrent analysis, with reference to preservation potential and sources of variance. Sedimentology, 9: 75-88. Allen, J.R.L., 1983. Studies in fluviatile sedimentation: bar-complexes and sandstone sheets (low-sinuosity braided streams) in the Brownstones (L. Devonian), Welsh Borders. Sediment. Geol., 33: 237-293. Allen, J.R.L. and Williams, B.P.J., 1979. Interfluvial drainage on Siluro-Devonian alluvial plains in Wales and the Welsh Borders. J. Geol. Soc., 136: 361-366. Allen, J.R.L., Thomas, R.G. and Williams, B.P.J., 1982. The Old Red Sandstone north of Milford Haven. In: M.G. Bassett (Editor), Geological Excursions in Dyfed, South-West Wales. Geologists' Association, South Wales Group, pp. 123-149. Allen, P.A., 1981. Sediments and processes on a small stream-flow dominated, Devonian alluvial fan, Shetland Islands. Sediment. Geol., 29: 31-66. Allen, P.A. and Homewood, P., 1984. Evolution and mechanics of a Miocene tidal sandwave. Sedimentology, 31: 63-81. Allen, P.A. and Matter, A., 1982. Oligocene meandering stream sedimentation in the easter Ebro Basin, Spain. Eclogae Geol. Helv., 75: 33-49. Andreasen, F., Brandt, G. and Clemmensen, L.B., 1982. Unusual types of backflow structures in Danish meltwater deposits. IAS 3rd European Meeting, Copenhagen, 1982, pp. 1-4 (abstract). Ashley, G.M., 1983. Sediment transport in a bedrock-floored reach, Raritan River, New Jersey. 22nd Annual General Meeting of the British Sedimentological Research Group, Birmingham.

58

Ashley, G.M. and Renwick, W.H., 1983. Channel morphology and processes at the riverine-estuarine transition, the Raritan River, New Jersey. In: J.D. Collinson and J. Lewin (Editors), Modern and Ancient Fluvial Systems. Spec. Publ. Int. Assoc. Sedimentol., 6: 207-218. Astin, T.R., 1981. The Clausta C o n g l o m e r a t e - - a Devonian sandur-like alluvial fan. 20th Annual Meeting of the British Sedimentological Research Group, Bristol. Backhaus, E., 1968. Fazies, Stratigraphie und Pal~ogeographie der Solling-Folge (Oberer Buntsandstein) zwischen Odenwald-Rh6n und Th~ringer Wald. Oberrhein. Geol. Abh., 17: 1-164. Backhaus, E., 1975. Schr~tgschichtungsmessungen im Grenzbereich des Mittleren/Oberen Buntsandsteins des Drachenfels (Pfalz). Mitt. Geol.-Pal~ontol. Inst. Univ. Hamburg, 44: 291-307. Backhaus, E., 1981. Der marin-brackische Einfluss im Oberen R6t St~ddeutschlands. Z. Dtsch. Geol. Ges., 132:361 382. Banks, N.L., 1973. Falling-stage features of a Precambrian braided stream: criteria for sub-aerial exposure. Sediment. Geol., 10: 147-154. Barrett, P.J., 1969. Stratigraphy and petrology of the mainly fluviatile Permian and Triassic Beacon rocks, Beardmore Glacier area, Antarctica. Inst. Polar Studies, Ohio State Univ. Rept., 34:132 pp. Barrett, P.J., 1970. Paleocurrent analysis of the mainly fluviatile Permian and Triassic Beacon rocks, Beardmore Glacier area, Antarctica. J. Sediment. Petrol., 40: 395-411. Behrensmeyer, A.K. and Tauxe, L., 1982. Isochronous fluvial systems in Miocene deposits of Northern Pakistan. Sedimentology, 29: 331-352. Bertelsen, F., 1980. Lithostratigraphy and depositional history of the Danish Triassic. Danm. Geol. Unders., Ser. B, 4 : 5 9 pp. Bhattacharyya, D.P. and Lorenz, J.C., 1983. Different depositional settings of the Nubian lithofacies in Libya and southern Egypt. In: J.D. Collinson and J. Lewin (Editors), Modern and Ancient Fluvial Systems. Spec. Publ. Int. Assoc. Sedimentol., 6: 435-448. Bluck, B.J., 1974. Structure and directional properties of some valley sandur deposits in Southern Iceland. Sedimentology, 21: 533-554. Bluck, B.J., 1979. Structure of coarse grained braided stream alluvium. Trans. R. Soc. Edinburgh, 70: 181-221. Bluck, B.J., 1980. Evolution of a strike-slip fault-controlled basin, Upper Old Red Sandstone, Scotland. In: P.F. Ballance and H.G. Reading (Editors), Sedimentation in Oblique-Slip Mobile Zones. Spec. Publ. Int. Assoc. Sedimentol., 4: 63-78. Boersma, J.R., Van der Meene, E.A. and Tjalsma, R.C., 1968. Intricated cross-stratification due to interaction of a mega ripple with its lee-side system of backflow ripples (upper-pointbar deposit, lower Rhine). Sedimentology, 11: 147-162. Braden, G.E., 1950. Turbulence, diffusion and sedimentation in stream channel expansions and contractions. Okla. Acad. Sci. Proc., 1950: 73-77. Bridge, J.S. and Diemer, J.A., 1983. Quantitative interpretation of an evolving ancient river system. Sedimentology, 30: 599-623. Button, A., 1975. A palaeocurrent study of the Dwaal Heuvel Formation, Transvaal Supergroup. Trans. Geol. Soc. S. Afr., 78: 173-183. Campbell, J.A., 1980. Lower Permian depositional systems and Wolfcampian paleogeography, Uncompahgre Basin, eastern Utah and southeastern Colorado. In: T.D. Fouch and E.R. Magathan (Editors), Paleozoic Paleogeography of the West-Central United States. Soc. Econ. Paleontol. Mineral., Rocky Mountain Section. Rocky Mountain Paleogeogr. Symp., I: 327-340. Cant, D.J., 1978. Development of a facies model for sandy braided river sedimentation: Comparison of the South Sasketchewan River and the Battery Point Formation. In: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mere., 5: 627-640. Cant, D.J. and Walker, R.G., 1976. Development of a braided-fluvial facies model for the Devonian Battery Point Sandstone, Quebec. Can. J. Earth Sci., 13: 102-119.

59

Cant, D.J. and Walker, R.G., 1978. Fluvial processes and facies sequences in the sandy braided South Sasketchewan River, Canada. Sedimentology, 25: 625-648. Casey, J.M., 1980. Depositional systems and paleogeographic evolution of the Late Paleozoic Taos Trough, Northern New Mexico. In: T.D. Fouch and E.R. Magathan (Editors), Paleozoic Paleogeography of the West-Central United States. Soc. Econ. Paleontol. Mineral., Rocky Mountain Section. Rocky Mountain Paleogeogr. Symp., 1:181 196. Clemmensen, L.B., 1978. Alternating aeolian, sabkha and shallow-lake deposits from the Middle Triassic Gipsdalen Formation, Scoresby Land, East Greenland. Palaeogeogr., Palaeoclimatol., Palaeoecol., 24: 111-135. Clemmensen, L.B., 1979. Triassic lacustrine red-beds and paleoclimate: The "Buntsandstein'" of Helgoland and the Malmros Klint Member of East Greenland. Geol. Rundsch., 68: 748-774. Clemmensen, L.B., 1980. Triassic rift sedimentation and paleogeography of central East Greenland. Groenl. Geol. Unders., Bull., 136:72 pp. Clemmensen, L.B., 1981. Forstenet blaesevejr. Vary, 1981:42 46. Coleman, J.M., 1969. Brahmaputra River: Channel processes and sedimentation. Sediment. Geol., 3: 129-239. Collinson, J.D., 1971. Current vector dispersion in a river of fluctuating discharge. Geol. Mijnbouw, 50: 671-678. Collinson, J.D., 1978. Vertical sequence and sand body shape in alluvial sequences. In: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mem., 5: 577-586. Cooper, M.A. and Marshall, J.D., 1981. Orient: a computer program for the resolution and rotation of palaeocurrent data. Comput. Geosci., 7: 153-165. Courel, L., Durand, M., Gall, J.C. and Jurain, G., 1973. Quelques aspects de la transgression triassique dans le nord-est de la France. Influence d'un eperon bourguignon. Rev. Geogr. Phys. G~ol. Dyn., 15: 547-554. Dabrio, C.J. and Fernandez, J., 1980. Secuencias originadas por migracion de rios arenosos de baja sinuosidad. Estud. Geol., 36: 371-381. Dachroth, W., 1980. Rehbergschichten. Mainzer Geowiss. Mitt., 9: 7-40. Dahlgr~hn, F., 1939. Geol. Ubersichtskarte Deutschland 1:200000, Blatt 137 Cochem. Reichsstelle for Bodenforschung, Berlin. Davies, D.K., 1966. Sedimentary structures and subfacies of a Mississippi River point bar. J. Geol., 74: 234-239. Davis, J.C., 1973. Statistics and Data Analysis in Geology. Wiley, New York, N.Y., 550 pp. Dawson, M., 1983. Facies sequences and sedimentary architecture associated with the Severn Main Terrace. 22nd Annual General Meeting of the British Sedimentological Research Group, Birmingham. Diessel, C.F.K., 1966. The determination of the direction of transport of fluviatile arenites by orientation analyses of the detrital mica. Sedimentology, 7: 167-177. Dodd, C., 1983. Aeolian-fluvial interactions in the Devonian Kilmurry Formation, Dingle, Eire. 22nd Annual General Meeting of the British Sedimentological Research Group, Birmingham. Dott, R.H., 1970. Limitations in paleocurrent analysis of trough cross-stratification. Bull. Am. Assoc. Pet. Geol., 54: 884-885. Dott, R.H., 1973. Paleocurrent analysis of trough cross-stratification. J. Sediment. Petrol., 43: 779-783. Durand, M., 1978. Pale?ocourants et reconstitution palGogdographique. L'exemple du Buntsandstein des Vosges m~Sridionales (Trias inf6rieur et moyen continental). Sci. Terre, 22: 301-390. Dzulynski, S. and Gradzinski, R., 1960. Source of the Lower Triassic elastics in the Tatra Mountains. Bull. Acad. Polon. Sci., 8: 45-48. Eisbacher, G., 1963. P r i m ~ e gerichtete Gefuge und Pal~togeographie des alpinen Buntsandsteins im R a u m e Innsbruck- Saalfelden. VerOff. Ferdinandeum Innsbruck, 43 : 133-141. Faria, L.E. do C., 1982. Zur Stratigraphie und Sedimentologie der Permo-Trias im Maranhao-Becken, N.E. Brasilien. Ph.D. Thesis, Univ. of Wgrzburg, Wgrzburg, 156 pp.

60

Ferguson, R.I. and Werritty, A., 1983. Bar development and channel changes in the gravelly River Feshie, Scotland. In: J.D. Collinson and J. Lewin (Editors), Modern and Ancient Fluvial Systems. Spec. Publ. Int. Assoc. Sedimentol., 6: 181-194. Fernandez, J., 1977. Sedimentation triasica en el borde sureste de la meseta. Ph.D. Thesis, Univ. of Granada, Granada, 173 pp. Fernandez, J. and Dabrio, C.J., 1978. An/disis sedimentol,Sgico de una capa de areniscas (Tri/tsico del borde SE de la Meseta Ib6rica). Estud. Geol., 34: 475-482. Fisher, R.A., 1953. Dispersion on a sphere. Proc. R. Soc. London, Ser. A, 217:295 305. Foster, R.J., 1972. The solid geology of North-East Caithness. Ph.D. thesis, Univ. of Newcastle-upon-Tync. Fox, W.T., 1967. Fortran IV program for vector trend analysis of directional data. Kansas Geol. Surv. Comp. Contrib., 11, 36 pp. Freeman, T. and Pierce, K., 1979. Field statistical assessment of cross-bed data. J. Sediment. Petrol., 49: 624-625. Friedman, G.M., Sanders, J.E. and Martini, I.P., 1982. Excursion 17A: Sedimentary facies: Products of sedimentary environments in a cross section of the classic Appalachian Mountains and adjoining Appalachian Basin in New York and Ontario. l l t h Int. Congress on Sedimentology, Hamilton, Ont., Field Excursion Guidebook. Friend, P.F. and Williams, B.P.J., 1978. International symposium on the Devonian System (P.A.D.S. 78), September 1978. A field guide to selected outcrop areas of the Devonian of Scotland, the Welsh Borderland and South Wales. Palaeontological Association, 106 pp. Fryberger, S.G., 1979. Eolian-fluviatile (continental) origin of ancient stratigraphic trap for petroleum in Weber Sandstone, Rangely oil field, Colorado. Mt. Geol., 16: 1-36. Gall, J.C., 1971. Faunes et paysages du Gr~s a Voltzia du Nord des Vosges. Essai palOodcologique sur le Buntsandstein superieur. M6m. Serv. Carte Geol. Alsace Lorraine, 34:318 pp. Galloway, W.E., Henry, C.D. and Smith, G.E., 1982. Depositional framework, hydrostratigraphy, and uranium mineralization of the Oakville Sandstone (Miocene), Texas Coastal Plain. Bur. Econ. Geol., Rept. Invest., 113:51 pp. Gayer, R.A. and Stead, J.T.G., 1971. The Forest of Dean coal and iron-ore fields. In: D.A. Bassctt and M.G. Bassett (Editors), Geological Excursions in South Wales and the Forest of Dean, Geologists' Association, South Wales Group, pp. 20-36. George, G.T., 1982. Sedimentology of the Upper Sandstone Group (Namurian G 1) in South-West Dyfed: a case study. In: M.G. Bassett (Editor), Geological Excursions in Dyfed, South-West Wales. Geologists' Association, South Wales Group, pp. 203-214. George, G.T. and Kelling, G., 1982. Stratigraphy and sedimentology of Upper Carboniferous sequences in the coalfield of South-West Dyfed. In: M.G. Bassett (Editor), Geological Excursions in Dyfed, South-West Wales. Geologists' Association, South Wales Group, pp. 175-201. Gilbert, G . K , 1914. The transportation of debris by running water. U.S. Geol. Surv., Prof. Pap., 86:236 pp. Glennie, K.W. and Buller, A.T., 1983. The Permian Weissliegend of N W Europe: the partial deformation of aeolian dune sands caused by the Zechstein transgression. Sediment. Geol., 35: 43-81. Gradzinski, R., Gagol, J. and Slaczka, A., 1979. The Tumlin Sandstone (Holy Cross Mts., Central Poland): Lower Triassic deposition of aeolian dunes and interdune areas. Acta Geol. Polon., 29: 151-175. Grumbt, E., 1974. Sedimentgefuge im Buntsandstein Siadwest- und Siadthi~ringens (ein Beitrag zur Untersuchung yon Rotsedimenten). Schriftenr. Geol. Wiss., 1:205 pp. Hand, B.M., Wessel, J.N. and Hayes, M.O., 1969. Antidunes in the Mount Toby Conglomerate (Triassic), Massachusetts. J. Sediment. Petrol., 39: 1310-1316. Haubold, H. and Puff, P., 1976. Zur Genese der Solling-Folge (Untere Trias, Buntsandstein) in Thihringen. Schriftenr. Geol. Wiss., 6: 63-80.

61

Hayes, M.O., Fayez, F.S. and Bozeman, R.N., 1969. Sediment dispersal trends in the littoral zone: a problem in paleogeographic reconstruction. Coastal Environ. Northeast. Mass. N. Hampshire, Contrib., 1: 290-315. Herrmann, A. and Hofrichter, E., 1962. Zur Fazies der Solling-Folge (Mittlerer Buntsandstein) in der n6rdlichen Hessischen Senke. Geol. Jahrb., 79: 551-564. Herrmann, A. and Hofrichter, E., 1963. Zur Faziesgliederung der tieferen Solling-Folge des Mittleren Buntsandsteins Si~dniedersachsens. Geol. Jahrb., 80: 653-740. High, L.R. and Picard, M.D., 1974. Reliability of cross-stratification types as paleocurrent indicators in fluvial rocks. J. Sediment. Petrol., 44: 158-168. Hiller, N. and Stavrakis, N., 1980. Distal alluvial fan deposits in the Beaufort Group of the Eastern Cape Province. Trans. Geol. Soc. S. Aft., 83: 353-360. Hiller, N. and Stavrakis, N., 1982. Reversed currents over a point bar on the Great Fish River. Trans. Geol. Soc. S. Afr., 85: 215-219. Hobday, D.K. and Mathew, D., 1974. Depositional environment of the Cape Supergroup in the Transkei. Trans. Geol. Soc. S. Aft., 77: 223-227. Hoyt, J.H., 1971. Measurement of sedimentary structure orientation. In: R.E. Carver (Editor), Procedures in Sedimentary Petrology. Wiley, New York, N.Y., pp. 3-20. Hubert, J.F., 1975. Triassic winds of the Connecticut Valley. Geol. Soc. Am., Abstr. with Programs, 7: 76-77. Hubert, J.F. and Hyde, M.G., 1982. Sheet-flow deposits of graded beds and mudstones in an alluvial sandflat-playa system: Upper Triassic Blomidon redbeds, St. Mary's Bay, Nova Scotia. Sedimentology, 29: 457-474. Hubert, J.F. and Mertz, K.A., 1980. Eolian dune field of Late Triassic age, F u n d y Basin, Nova Scotia. Geology, 8: 516-519. Hubert, J.F., Reed, A.A. and Carey, P.J., 1976. Paleogeography of the East Berlin Formation, Newark Group, Connecticut Valley. Am. J. Sci., 276: 1183-1207. Hubert, J.F., Reed, A.A., Dowdall, W.L. and Gilchrist, J.M., 1978. Gnide to the Mesozoic redbeds of Central Connecticut. Contrib. Dept. Geol. Geogr. Univ. Mass., 32:129 pp. Jackson II, R.G., 1978. Preliminary evaluation of lithofacies models for meandering alluvial streams. In: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mem., 5: 543-576. Johnsen, J.R., 1981. Facies analysis of Permo-Triassic sediments on the eastern margin of the North Minch Basin, North West Scotland. Cand. Real. Thesis, Uniy. of Bergen, Bergen, 384 pp. Johnson, S.Y., 1981. Evidence for two coalescing fluvial systems in the Eocene Chuckanut Formation, North Cascades, Washington. Modern and Ancient Fluvial Systems: Sedimentology and Processes. University of Keele, Keele, p. 61 (abstract). Jungblut, G., 1982. Sedimentologische und tektonische Untersuchungen in der Trias des S-aarburger Landes. M. Sc. thesis, Univ. of Aachen, Aachen, 140 pp. Kelling, G., 1964. Sediment transport in part of the Lower Pennant Measures of South Wales. In: L.M.J.U. van Straaten (Editor), Deltaic and Shallow Marine Deposits. (Developments in Sedimentology, 1) Elsevier, Amsterdam, pp. 177-184. Kelling, G., 1968. Patterns of sedimentation in R h o n d d a Beds of south Wales. Bull. Am. Assoc. Pet. Geol., 52: 2369-2386. Kelling, G., 1969. The environmental significance of cross-stratification parameters in an Upper Carboniferous fluvial basin. J. Sediment. Petrol., 39: 857-875. Kelling, G., 1971. Upper Carboniferous sedimentation in the central part of the South Wales coalfield. In: D.A. Bassett and M.G. Bassett (Editors), Geological Excursions in South Wales and the Forest of Dean. Geologists' Association, South Wales Group, pp. 85-95. Kelling, G. and George, G.T., 1971. Upper Carboniferous sedimentation in the Pembrokeshire coalfield. In: D.A. Bassett and M.G. Bassett (Editors), Geological Excursions in South Wales and the Forest of Dean. Geologists' Association, South Wales Group, pp. 240-259.

62 Koch, G.S. and Link, R.F., 1971. Statistical Analysis of Geological Data, Vol. 2, Wiley, New York, N.Y. Krapez, B., 1981. A model for very proximal placer types in the Proterozoic Venterspost Formation, Carletonville Goldfield, South Africa. Modern and Ancient Fluvial Systems: Sedimentology and Processes. University of Keele, Keele (abstracts). Kruhl, J., 1978. Current bedding in the Moinian quartzites at eastern Loch Leven, Scottish Highlands. N. Jahrb. Mineral. Abh., 132: 52-65. Kumar, S. and Bhandari, L.L., 1973. Paleocurrent analysis of the Athgarh Sandstone (Upper Gondwana), Cuttack District, Orissa (India). Sediment. Geol., 10: 61-75. Kurtz, D.D. and Anderson, J.B., 1980. Depositional environments and paleocurrents of Chinle Formation (Triassic), Eastern San Juan Basin, New Mexico. N. Mex. Geol., 2 : 2 2 27. Laming, D.J.C., 1966. Imbrications, paleocurrents and other sedimentary features in the Lower New Red Sandstone, Devonshire, England. J. Sediment. Petrol., 36: 940-959. Laming, D.J.C., 1982. The New Red Sandstone. In: E.M. Durrance and D.J.C. Laming (Editors), The Geology of Devon. Exeter Univ. Publ., Exeter, pp. 148-178. Lawrence, D.A., 1983. Multi-storey fluvial channel belt sandstone in the Lower Devonian Battery Point Formation, Gaspr, E. Quebec. 22nd Annual General Meeting of the British Sedimentological Research Group, Birmingham. Leeder, M.R. and Bridges, P.H., 1975. Flow separation in meander bends. Nature, 253: 338-339. Leitz, F., 1976. Lithostratigraphie des Zechsteins und Buntsandsteins bei C o b u r g - K r o n a c h (NordostBayern). Ph.D. thesis, Univ. of Bochum, Bochum, 185 pp. Long, D.G.F., 1978. Proterozoic stream deposits: Some problems of recognition and interpretation of ancient sandy fluvial systems. In: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mem., 5: 313-341. Long, D.G.F. and Young, G.M., 1978. Dispersion of cross-stratification as a potential tool in the interpretation of Proterozoic arenites. J. Sediment. Petrol., 48: 857-862. Lucas, C., 1977. Le Trias des Pyrenees, corrrlations stratigraphiques et palrogrographie. Bull. B.R.G.M., 2. Ser., Sect. IV, 3: 225-231. L~thi, S., 1983. Recognising sedimentary features in borehole using the dipmeter tool. 4th I.A.S. Regional Meeting, Split, Yugoslavia, April 1983, p. 96 (abstract). Mader, D., 1979. Stratigraphie und Faziesanalyse im Buntsandstein der Westeifel. Ph.D. Thesis, Univ. of Heidelberg, Heidelberg, 293 pp. Mader, D., 1980a. Pal~towindrichtungen und Palaostrrmungsrichtungen im Mittleren Buntsandstein der Westeifel. Geol. Rundsch., 69: 922-942. Mader, D., 1980b. Aeolische und fluviatile Sedimentation im Mittleren Buntsandstein der Westeifel. N. Jahrb. Geol. Palaontol. Abh., 160: 1-41. Mader, D., 1980c. Petrographie und Genese der Br'Ockelb~nke im Oberen Buntsandstein der Westeifel. Oberrhein. Geol. Abh., 29: 1-28. Mader, D., 1981a. Genesis of the Buntsandstein (Lower Triassic) in the Western Eifel (Germany). Sediment. Geol., 29: 1-30. Mader, D., 1981b. Fluviatile Sedimentation im Oberen Buntsandstein der Westeifel. Z. Dtsch. Geol. Ges., 132: 383-420. Mader, D., 1981c. Pal~ostrrmungsrichtungen im Oberen Buntsandstein der Westeifel. Z. Geol. Wiss., 9: 501-518. Mader, D., 1981d. Diagenesis of the Buntsandstein (Lower Triassic) in Western Eifel (Germany). N. Jahrb. Miner. Abh., 142: 1-26. Mader, D., 1982a. Aeolian sands in continental red beds of the Middle Buntsandstein (Lower Triassic) at the western margin of the German Basin. Sediment. Geol., 31: 191-230. Mader, D., 1982b. Sedimentologie und Genese des Buntsandsteins in der Eifel. Z. Dtsch. Geol. Ges., 133: 257-307.

63

Mader, D., 1983a. Aeolische und fluviatile Sedimentation im Mittleren Buntsandstein der Nordeifel. N. Jahrb. Geol. Pal~ontol. Abh., 165: 254-302. Mader, D., 1983b. Evolution of fluvial sedimentation in the Buntsandstein (Lower Triassic) of the Eifel (Germany). Sediment. Geol., 37: 1-84. Mader, D., 1984a. Entstehung der fluviatilen Sedimente in der grobklastischen Marginalfazies im Oberen Buntsandstein von Luxemburg. N. Jahrb. Geol. Pal~ontol. Abh., 168: 23-86. Mader, D., 1984b. Depositional environment, cartographic representation and palaeogeography of the Buntsandstein in the Mid-European Triassic Basin. In: G. Li)ttig (Editor), Europe on the Geological Map. Proc. Third Meeting of the European Geological Societies. Schweizerbart, Stuttgart. Mader, D., 1984c. Entstehung der grobklastischen fluviatilen Sedimente im Mittleren Buntsandstein der Nordeifel und Vergleich mit der Bildung anderer alluvialer Konglomerate. Submitted for publication. Mader, D., 1985. Fluvial conglomerates in continental red beds of the Buntsandstein (Lower Triassic) in the Eifel ( F R . G ) . Sediment. Geol. (in press). M~kcl, G.H., 1982. Statistical analysis of paleocurrent directions in the Malaguide Complex in the zone from Chirivel to the Sierra de Espuna (Betic Cordilleras, Spain). Proc. Kon. Ned. Akad. Wet., B, 85: 241-248. Mardia, K.V., 1972. Statistics of Directional Data. Academic Press, London, 357 pp. Marshall, J.D., 1978. Sedimentology of the Skrinkle Sandstones Group (Devonian-Carboniferous), South West Dyfed. Ph.D. Thesis, Univ. of Bristol, Bristol, 371 pp. Marzolf, J.E., 1982. Paleogeographic implications of the Early Jurassic(?) Navajo and Aztec Sandstones. In: E.G. Frost and D.L. Martin (Editors), Mesozoic-Cenozoic Tectonic Evolution of the Colorado River Region, California, Arizona, and Nevada. Geol. Soc. Am., pp. 493-501. Massari, F., 1983. Tabular cross-bedding in Messinian fluvial channel conglomerates, Southern Alps, Italy. In: J.D. Collinson and J. Lewin (Editors), Modern and Ancient Fluvial Systems. Spec. Publ. Int. Assoc. Sedimentol., 6: 287-300. Mathisen, M.E. and Vondra, C.F., 1983. The fluvial and pyroclastic deposits of the Cagayan Basin, Northern Luzon, Philippines--an example of non-marine volcaniclastic sedimentation in an interarc basin. Sedimentology, 30: 369-392. Mattis, A.F., 1977. N o n m a r i n e Triassic sedimentation, Central High Atlas Mountain, Morocco. J. Sediment. Petrol., 47: 107-119. McDonnell, K.L., 1974. Depositional environments of the Triassic Gosford Formation, Sydney Basin. J. Geol. Soc. Aust., 21: 107-132. McGowen, J.S. and Garner, L.E., 1970. Physiographic feaiures and stratification types of coarse-grained point bars: modern and ancient examples. Sedimentology, 14: 77-111. McKee, E.D., 1982. The Supai Group of Grand Canyon. U.S. Geol. Surv., Prof. Pap., 1173:504 pp. McLean, J.R. and Jerzykiewicz, T., 1978. Cyclicity, tectonics and coal: some aspects of fluvial sedimentology in the Brazeau-Paskapoo Formations, Coal Valley area, Alberta, Canada. In: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mem., 5: 441-468. Meckel, L.D., 1967. Tabular and trough cross-bedding: comparison of dip azimuth variability. J. Sediment. Petrol., 37: 80-86. Mehrabi, F., 1978. Die Achsenverteilungsanalyse von QuarzkiSrnern in einem OdenwNder Sandstein. M.Sc. thesis, Univ. of Heidelberg, Heidelberg, 74 pp. Miall, A.D., 1974. Paleocurrent analysis of alluvial sediments: a discussion of directional variance and vector magnitude. J. Sediment. Petrol., 44: 1174-1185. Miall, A.D., 1976. Paleocurrent and paleohydraulic analysis of some vertical profiles through a Cretaceous braided stream deposit, Banks Island, Arctic Canada. Sedimentology, 23: 459-483. Miall, A.D., 1977. A review of the braided-river depositional environment. Earth-Sci. Rev., 13: 1-62. Miall, A.D., 1978. Lithofacies types and vertical profile models in braided river deposits: a summary. In: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mem., 5: 597-604.

64

Miall, A.D., 1980. Cyclicity and the facies model concept in fluvial deposits. Bull. Can. Pet. Geol., 28: 59-80. Michelson, P.C. and Dott, R.H., 1973. Orientation analysis of trough cross-stratification in Upper Cambrian sandstones of Western Wisconsin. J. Sediment. Petrol., 43: 784-794. Middleton, G.V., 1965. Antidune cross-bedding in a large flume. J. Sediment. Petrol., 35: 922-927. Middleton, L.T. and Blakey, R.C., 1983. Processes and controls on the intertonguing of the Kayenta and Navajo Formations, northern Arizona: eolian-fluvial interactions. In: M.E. Brookfield and T.S. Ahlbrandt (Editors), Eolian Sediments and Processes. (Developments in Sedimentology, 38) Elscvier, Amsterdam, pp. 613-634. Miller, R.L., 1956. Trend surfaces: their application to analysis and description of environments of sedimentation. J. Geol., 64: 425-446. Miller, R.L. and Kahn, J.S., 1962. Statistical Analysis in the Geological Sciences. Wiley, New York, N.Y., 483 pp. Minter, W.E.L., 1978. A sedimentological synthesis of placer gold, uranium and pyrite concentrations in Proterozoic Witwatersrand sediments. In: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mem., 5: 801-830. Morgan, J.P., 1970. Depositional processes and products in the deltaic environment. In: J.P. Morgan (Editor), Deltaic Sedimentation. Soc. Econ. Paleontol. Mineral., Spec. Publ., 15: 31-47. Mowbray, T.D. and Visser, M., 1982. Subordinate current reactivation surfaces and the recognition of tidal deposits. IAS 3rd European Meeting, Copenhagen 1982, pp. 52-54 (abstract). Mroczkowski, J., 1969. Paleocurrents in the Lower Triassic deposits of the southern part of the Northsudetic Basin. Bull. Acad. Polon. Sci., 17: 167-172. Mroczkowski, J., 1972. Sedimentation of the Bunter in the Northsudetic Basin. Acta Geol. Polon., 22: 351-377. Mroczkowski, J., 1977. Lower Triassic sandstones in the northern part of the Intra-Sudetic trough. Annal. Soc. Geol. Polon., 47: 49-72. Nagtegaal, P.J.C., 1969. Sedimentology, paleoclimatology, and diagenesis of post-Hercynian continental deposits in the South Central Pyrenees, Spain. Leidse Geol. Meded., 42: 143-238. Nagy, E., 1968. Triasbildungen des Mecsek-Gebirges. Jahrb. Ungar. Geol. Anstalt, 51: 125-198. Nanson, G.C., 1980. Point bar and floodplain formation of the meandering Beatton River. northeastern British Columbia, Canada. Sedimentology, 27: 3-29. Nemec, W., 1983. Helvetiafjellet Formation (Cretaceous: Svalbard): The braided distributary sandstone sequences. 22nd Annual General Meeting of the British Sedimentological Research Group, Birmingham. Nijman, W. and Puigdefabregas, C., 1978. Coarse-grained point bar structure in a molasse-type fluvial system, Eocene Castisent Sandstone Formation, South Pyrenean Basin. In: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mem., 5: 487-510. Okolo, S.A., 1983. Fluvial distributary channels in the Fletcher Bank Grit (Namurian R2~ ) at Ramsbottom, Lancashire, England. In: J.D. Collinson and J. Lewin (Editors), Modern and Ancient Fluvial Systems. Spec. Publ. Int. Assoc. Sedimentol., 6: 421-434. Ore, H.T., 1964. Some criteria for recognition of braided stream deposits. Univ. Wyoming, Dept. Geol., Contrib. Geol., 3: 1-14. Ortlam, D., 1974. Inhalt und Bedeutung fossiler Bodenkomplexe in Perm und Trias von Mitteleuropa. Geol. Rundsch., 63: 850-884. Parks, J.M., 1974. Paleocurrent analysis of sedimentary cross-bed data with graphic output using three integrated computer programs. J. Int. Assoc. Math. Geol., 6: 353-362. Payne, J.B. and Scott, A.J., 1982. Late Cretaceous anastomosing fluvial systems, Northwestern Colorado. Bull. Am. Assoc. Pet. Geol., 66: p. 616. Pelletier, B.R., 1958. Pocono paleocurrents in Pennsylvania and Maryland. Geol. Soc. Am. Bull., 69: 1033-1064. Pelletier, B.R., 1965. Paleocurrents in the Triassic of Northeastern British Columbia. In: G.V. Middleton

65

(Editor), Primary Sedimentary Structures and their Hydrodynamic Interpretation. Soc. Econ. Paleontol. Mineral., Spec. Publ., 12: 233-245. Perriaux, J., 1961. Contributions b, la g6ologie des Vosges gr6seuses. M6m. Serv. Carte Geol. Alsace Lorraine, 18:236 pp. Perriaux, J. and MUller, E.M., I961. Quelques directions des courants dans le Buntsandstein de la Sarre et de Lorraine septentrionale. Bull. Soc. G6ol. Ft., S~r. 7, 3: 625-628. Picard, M.D. and High, L.R., 1970. Interference ripple marks formed by ephemeral streams. J. Sediment. Petrol., 40: 708-711. Picard, M.D. and High, L.R., 1973. Sedimentary Structures of Ephemeral Streams. (Developments in Sedimentology, 17) Elsevier, Amsterdam, 215 pp. Pienkowski, G., 1983. Early Lias sedimentary environments at northern margin of the Holy Cross Mrs. Przegl. Geol., 360: 223-230. Pincus, H.J., 1953. The analysis of aggregates of orientation data in the earth sciences. J. Geol., 61: 482-509. Plint, A.G., 1983. Sandy fluvial point-bar sediments from the Middle Eocene of Dorset, England. In: J.D. Collinson and J. Lewin (Editors), Modern and Ancient Fluvial Systems. Spec. Publ. Int. Assoc. Sedimentol., 6: 355-368. Plummer, P.S. and Leppard, P.I., 1979. An analytical technique for uni-, bi- and trimodal palaeocurrent data. Comput. Geosci., 5: 157-172. Poole, F.G., 1961. Stream directions in Triassic rocks of the Colorado Plateau. U.S. Geol. Surv., Prof. Pap., 424C: 139-141. Poole, F.G., 1962. Wind directions in Late Paleozoic to Middle Mesozoic time on the Colorado Plateau. U.S. Geol. Surv., Prof. Pap., 450D: 147-151. Poole, F.G., 1964. Paleowinds in western U.S.A. In: A.E.M. Nairn (Editor), Problems in Palaeoclimatology. Wiley-lnterscience, New York, N.Y., pp. 390-405. Potter, P.E. and Pettijohn, F.J., 1977. Paleocurrents and Basin Analysis (2nd ed.), Springer, Berlin, 425 pP. Power. W.R., 1961. Backset beds in the Coso Formation, Inyo Country, California. J. Sediment. Petrol., 31 : 603-607. Prestegaard, K.L., 1984. Variables influencing water-surface slopes in gravel-bed streams at bankfull stage. Geol. Soc. Am. Bull., 94: 673-678. Puff, P., 1976. Gliederung der Solling-Folge (Trias, Buntsandstein) im s~dlichen Thi~ringen mittels Violetter Horizonte. Schriftenr. Geol. Wiss., 6: 81-96. Puigdefabregas, C. and Van Vliet, A., 1978. Meandering stream deposits from the Tertiary of the southern Pyrenees. In: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mem., 5: 469-486. Ramberg, I.B. and Spjeldnaes, N., 1978. The tectonic history of the Oslo region. In: I.B. Ramberg and E.R. N e u m a n n (Editors), Tectonics and Geophysics of Continental Rifts. Reidel, Dordrecht, pp. 167-194. Ramos, A., 1979. Estratigrafia y paleogeografia del Permico y Triasico al oeste de Molina de Aragon. Ph.D. Thesis, Univ. of Madrid, Madrid, 313 pp. (Seminarios de Estratigrafia, Serie Monografias, No. 6). Ramos, A. and Friend, P.F., 1982. Upper Old Red Sandstone sedimentation near the unconformity at Arbroath (Scotland). Scott. J. Geol., 18: 297-315. Ramos, A. and Sopena, A., 1983. Gravel bars in low-sinuosity streams (Permian and Triassic, central Spain). In: J.D. Collinson and J. Lewin (Editors), Modern and Ancient Fluvial Systems. Spec. Publ. Int. Assoc. Sedimentol., 6: 301-312. Rao, J.S. and Sengupta, S., 1972. Mathematical techniques for paleoeurrent analysis: treatment of directional data. J. Int. Assoc. Math. Geol., 4: 235-248. Rast, U. and Sch~fer, A., 1978. Delta-Sch~ttungen in Seen des hOheren Unterrotliegenden im Saar-Nahe-Becken. Mainzer Geowiss. Mitt., 6: 121-159.

66

Rawson, R.R. and Turner-Peterson, C.E., 1980. Paleogeography of Northern Arizona during the deposition of the Permian Toroweap Formation. In: T.D. Fouch and E.R. Magathan (Editors), Paleozoic Paleogeography of the West-Central United States. Soc. Econ. Paleontol. Mineral., Rocky Mountain Section. Rocky Mountain Paleogeogr. Symp., 1: 341-352. Richter-Bernburg, G., 1974. Stratigraphische Synopsis des deutschen Buntsandsteins. Geol. Jahrb., Reihe A, 25: 127-132. Roe, S.L., 1983. Sedimentary structures of dune-plane bed (upper stage) transitional origin: examples from a low sinuosity stream deposit (Late Precambrian), Northern Norway. 22nd Annual General Meeting of the British Sedimentological Research Group, Birmingham. Rust, B.R., 1972. Structure and process in a braided river. Sedimentology, 18: 221-246. Rust, B.R., 1975. Fabric and structures in glaciofluvial gravels. In: A.V. Jopling and B.C. McDonald (Editors), Glaciofluvial and Glaciolacustrine Sedimentation. Soc. Econ. Paleontol. Mineral., Spec. Publ., 23: 238-248. Rust, B.R., 1978. A classification of alluvial channel systems. In: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mem., 5: 187-198. Scheidegger, A.E., 1965. On the statistics of the orientation of bedding planes, grain axis, and similar sedimentological data. U.S. Geol. Surv., Prof. Pap., 525-C: 164-167. Schiedt, H.R., 1968. Ausbildung und Lagerungsverh~tnisse des hrheren Buntsandsteins und Unteren Muschelkalkes auf der westlichen Sickinger H r h e in der Westpfalz. M. Sc. Thesis, Univ. of Ti?bingen, T~bingen, 95 pp. Schrader, E., 1983. Ein Sedimentationsmodell der Trias in der Eifeler Nord-Sgd-Zone. Untersuchungen zur Granulometrie, Mikrofazies und Tongeologie sowie Betrachtungen zum naturr~.umlichen Potential der Nord-Eifel. Ph. D. Thesis, Univ. of Aachen, Aachen, 300 pp. Schumm, S.A., 1981. Evolution and response of the fluvial system, sedimentologic implications. In: F.G. Ethridge and R.M. Flores (Editors), Recent and Ancient Nonmarine Depositional Environments: Models for Exploration. Soc. Econ. Paleontol. Mineral., Spec. Publ., 31: 19-29. Schuster, M., 1934. Die Gliederung des Unterfr~ankischen Buntsandsteins. II. Der Obere Buntsandstein oder das Rrt. b. Das untere R/3t oder die Stufe des Plattensandsteins. Abh. Geol. Landesunters. Bayer. Oberbergamt, 15: 1-64. Schwartz, D.E., 1978. Hydrology and current orientation analysis of a braided-to-meandering transition: the Red River in Oklahoma and Texas, U.S.A. In: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mere., 5: 231-256. Schwarz, H.U., 1975. Sedimentary structures and facies analysis of shallow marine carbonates (Lower Muschelkalk, Middle Triassic, southwestern Germany). Contrib. Sedimentol., 3 : 1 0 0 pp. Selley, R.C., 1965. Diagnostic characters of fluviatile sediments of the Torridonian Formation (Precambrian) of Northwest Scotland. J. Sediment. Petrol., 35: 366-380. Selley, R.C., 1968. A classification of paleocurrent models. J. Geol., 76: 99-110. Selley, R.C., 1969. Torridonian alluvium and quicksands. Scott. J. Geol., 5: 328-346. Sengupta, S., 1966. Paleocurrents and depositional environments of the G o n d w a n a rocks around Bheemaram: a preliminary study. Geol. Soc. India Bull., 3: 5-8. Sengupta, S., 1970. G o n d w a n a sedimentation around Bheemaram (Bhimaram), Pranhita-Godavari Valley, India. J. Sediment. Petrol., 40: 140-170. Sengupta, S., 1974. Fluviatile cross-stratifications--ancient, recent and experimental. Contrib. Earth Planet. Sci.; Geol. Min. Metall. Soc. India, Golden Jubilee Volume, pp. 87-99. Sengupta, S. and Rao, J.S., 1966. Statistical analysis of cross-bedding azimuths from the Kamthi formation around Bheemaram, Pranhita-Godavari valley. Indian J. Statistics, Ser. B, 28: 165-174. Senkowiczowa, H. and Slaczka, A., 1962. The Bunter on the northern border of the Holy Cross Mts. Ann. Soc. Geol. Polon., 32: 313-338. Senkowiczowa, H. and Szyperko-Sliwczynska, A., 1975. Stratigraphy and palaeogeography of the Trias. Bull. Geol. Inst., 252: 131-147.

67

Shakesby, R.A., 1981. The application of trend surface analysis to directional data. Geol. Mag., 118: 39-48. Shelton, J.W. and Mack, D.E., 1970. Grain orientation in determination of paleocurrents. Bull. Am. Assoc. Pet. Geol., 54: 1108-1119. Shelton, J.W. and Noble, R.L., 1974. Depositional features of a braided-meandering stream. Bull. Am. Assoc. Pet. Geol., 58: 742-752. Shelton, J.W., Burman, H.R. and Noble, R.L., 1974. Directional features in braided-meandering stream deposits, Cimarron River, north-central Oklahoma. J. Sediment. Petrol., 44: 1114-1117. Siegenthaler, C., 1978. Computer programs for sedimentological data. MASE report Nr. 3, 40 pp., Comparative Sedimentology Division, State University of Utrecht, Utrecht (unpubl.). Simon, J.B. and Bluck, B.J., 1982. Paleodrainage of the southern margin of the Caledonian mountain chain in the northern British Isles. Trans. R. Soc. Edinburgh, 73: 11-15. Smith, N.D., 1970. The braided stream depositional environment: comparison of the Platte River with some Silurian clastic rocks, North-Central Appalachians. Geol. Soc. Am. Bull., 81: 2993-3014. Smith, N.D., 1972. Some sedimentological aspects of planar cross-stratification in a sandy braided river. J. Sediment. Petrol., 42: 624-634. Smith, N.D., 1978. Some comments on terminology for bars in shallow rivers. In: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mere., 5: 85-88. Sopena, A., 1979. Estratigrafia del Permico y Triasico del noroeste de la Provincia de Guadalajara. Ph. D. Thesis, Univ. of Madrid, Madrid, 329 pp. (Seminarios de Estratigrafia, Serie Monografias, No. 5). Sorby, H.C., 1859. On the structures produced by the current present during the deposition of stratified rocks. Geologist, 2: 137-147. Stanley, K.O. and Fagerstrom, J.A., 1974, Miocene invertebrate trace fossils from a braided river environment, western Nebraska, U.S.A. Palaeogeogr., Palaeoclimatol., Palaeoecol., 15: 63-82. Stavrakis, N., 1980. Sedimentation of the Katberg Sandstone and adjacent formations in the South-Eastern Karoo Basin. Trans. Geol. Soc. S. Afr. 83: 361-374. Stear, W.M., 1980. Channel sandstone and bar morphology of the Beaufort Group U r a n i u m District near Beaufort West. Trans. Geol. Soc. S. Afr., 83: 391-398. Steel, R.J., 1976. Devonian basins of western Norway: sedimentary response to tectonism and the varying tectonic context. Tectonophysics, 36: 207-224. Steel, R.J., 1977. Observations on some Cretaceous and Tertiary sandstone bodies in Nordenski~51d Land, Svalbard. Norsk Polarinst. Arbok, 1976: 43-68. Steel, R. and Aasheim, S.M., 1978. Alluvial sand deposition in a rapidly subsiding basin (Devonian, Norway). In: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mem., 5: 385-412. Steel, R.J. and Thompson, D.B., 1983. Structures and textures in Triassic braided stream conglomerates ('Bunter' Pebble Beds) in the Sherwood Sandstone Group, north Staffordshire, England. Sedimentology, 30: 341-367. Steel, R.J. and Wilson, A.C., 1975. Sedimentation and tectonism (?Permo-Triassic) on the margin of the North Minch basin, Lewis. J. Geol. Soc., London, 131: 183-202. Steinmetz, R., 1972. Sedimentation of an Arkansas River sand bar in Oklahoma: A cautionary note on dipmeter interpretation. Shale Shaker, 16: 32-37. Steinmetz, R., 1975. Cross-bed reliability in a single sand body. In: E.H.T. Whitten (Editor), Quantitative Studies in the Geological Sciences. Geol. Soc. Am. Mem., 142: 89-102. Steinmetz, R., 1978. A n a t o m y of an Arkansas River sand bar. Geol. Soc. Am., Abstr. with Programs, 10: p. 26; and in: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mem., 5: p. 858. Stephens, M.A., 1963. R a n d o m walk on a circle. Biometrica, 50: 385-390. Stets, J. and Wurster, P., 1977. Der Lichtenauer Randstrom des Schilfsandstein-Deltas. Z. Dtsch. Geol. Ges., 128: 99-120. Stewart, D.J., 1981. A meander-belt sandstone of the Lower Cretaceous of Southern England. Sedimentology, 28: 1-20.

68

Stewart, J.H., Poole F.G. and Wilson, R.F., 1972. Stratigraphy and origin of the Chinle Formation and related upper Triassic strata in the Colorado Plateau region. U.S. Geol. Surv., Prof. Pap., 690:336 pp. Strack, D. and Stapf, K.R.G., 1980. Ist der Kreuznacher Sandstein im Rotliegenden ~olisch oder fluviatil entstanden? Geol. Rundsch., 69: 892-921. Szabo, J., 1965. Geologische Auswertung der Angaben ~ber die Schr~gschichtung des Oberperms und Unterseis im Mecsekgebirge (S~dungarn). Bull. Hung. Geol. Soc., 95: 40-46. Taylor, G., Crook, K.A.W. and Woodyer, K.D., 1971. Upstream-dipping foreset cross-stratification: origin and implications for paleoslope analyses. J. Sediment. Petrol., 41: 578-581. Tewari, R.C. and Casshyap, S.M., 1982. Paleoflow analysis of late Paleozoic Gondwana deposits of Giridih and adjoining basins and paleogeographic implications. J. Geol. Soc. India, 9: 67-79. Teyssen, T., 1983. Gezeitenbeeinflusste Sedimentation und Sandwellenentwicklung in der Minette (Toarcium/Aalenium, Luxemburg/Lothringen). Ph.D. thesis, Univ. of Bonn, Bonn, 180 pp. Teyssen, T.A.L., 1984. Sedimentology of the Minette oolitic ironstones of Luxembourg and Lorraine: A Jurassic subtidal sandwave complex. Sedimentology, 31: 195-211. Teyssen, T. and Vossmerb~iumer, H., 1979. Transportrichtungen im Mittleren Buntsandstein Nordostbayerns. Z. Geol. Wiss., 7: 1411-1417. Teyssen, T. and Vossmerb~tumer, H., 1980. Schr~tgschichtungs-analyse am Beispiel des Buntsandsteins in Nordbayern. N. Jahrb. Geol. Pal~ontol. Mh., 10: 620-642. Thompson, D.B., 1969. Dome-shaped dunes in the Frodsham Member of the so-called " K e u p e r " Sandstone Formation (Scythian-?Anisian : Triassic) at Frodsham, Cheshire, England. Sediment. Geol., 3: 263-289. Thompson, D.B., 1970. Sedimentation of the Triassic (Scythian) Red Pebbly Sandstones in the Cheshire Basin and its margins. Geol. J., 7: 183-216. Thrivikramaji, K.P. and Merriam, D.F., 1975. Trend analysis of sedimentary thickness data: The Pennsylvanian of Kansas, an example. In: D.F. Merriam (Editor), Quantitative Techniques for the Analysis of Sediments. Pergamon Press, New York, N.Y., pp. 11-21. Tunbridge, I.P., 1981. Old Red Sandstone sedimentation an example from the Brownstones (highest Lower Old Red Sandstone) of South Central Wales. Geol. J., 16: 111-124. Turner, B.R., 1975a. The stratigraphy and sedimentary history of the Molteno Formation in the Main Karoo Basin of South Africa and Lesotho. Ph. D. thesis, Univ. of Witwatersrand, Witwatersrand, 314 pp. Turner, B.R., 1975b. Statistical appraisal of Molteno (Triassic) sedimentary cycles from the upper part of the Karoo (Gondwana) System in South Africa. J. Sediment. Petrol., 45: 95-104. Turner, B.R., 1977. Fluviatile cross-bedding patterns in the Upper Triassic Molteno Formation of the Karoo (Gondwana) Supergroup in South Africa and Lesotho. Trans. Geol. Soc. S. Afr., 80:241 252. Turner, B.R., 1980. Palaeozoic sedimentology of the southeastern part of A1 Kufrah Basin, Libya: a model for oil exploration. In: M.J. Salem and M.T. Busrewil (Editors), The Geology of Libya, 2. Turner, B.R., 1983. Braidplain deposition of the Upper Triassic Molteno Formation in the main Karoo (Gondwana) Basin, South Africa. Sedimentology, 30: 77-89. Van Wijhe, D.H., Lutz, M. and Kaasschieter, J.P.H., 1980. The Rotliegend in the Netherlands and its gas accumulations. Geol. Mijnbouw, 59: 3-24. Visser, M.J., 1980. N e a p - s p r i n g cycles reflected in Holocene subtidal large-scale bedform deposits: A preliminary note. Geology, 8: 543-546. Visser, M. and Mowbray, T.D., 1982. Large-scale cross-bedded sets in subrecent and fossil depositional environments. IAS 3rd European Meeting, Copenhagen 1982, pp. 91-92 (abstract). Vistelius, A.B., 1961. Sedimentation time-trend functions and their application for correlation of sedimentary deposits. J. Geol., 69: 703-728. Vossmerb~umer, H., 1979. StrOmungsrichtungen im Plattensandstein (Trias, Oberer Buntsandstein) Frankens. Geol. B1. NO-Bayern, 29: 50-61.

69

Walther, H.W. and Zitzmann, A., 1969. Geologische Karte der Bundesrepublik Deutschland 1 : 1,000,000 und benachbarter Gebiete. Bundesanstalt for Geowissenschaften, Hannover. Wessel, J.M., 1969. Sedimentary history of upper Triassic alluvial fan complexes in North-Central Massachusetts. Dept. Geol. Univ. Mass. Contrib., 2. Wells, N.A., 1983. Transient streams in sand-poor redbeds: early-Middle Eocene Kuldana Formation of northern Pakistan. In: J.D. Collinson and J. Lewin (Editors), Modern and Ancient Fluvial Systems. Spec. Publ. Int. Assoc. Sedimentol., 6: 393-404. Wiebel, M., 1968. Uber die Trias am Si~drande der Luxemburger Ardennen. Oberrhein. Geol. Abh., 17: 165-192. Williams, G.E., 1966. Planar cross-stratification formed by the lateral migration of shallow streams. J. Sediment. Petrol., 36: 742-746. Williams, H., 1983. Delta-plain facies of the Westphalian A, South Derbyshire Coalfield. 22nd Annual General Meeting of the British Sedimentological Research Group, Birmingham. Wilson, A.C., 1971. Lower Devonian sedimentation in the north-west Midland Valley of Scotland. Ph.D. thesis, Univ. of Glasgow, Glasgow. Wolniczak, K., 1981. Geologische Karte von Bayern 1:500,000 (3rd ed.). Bayerisches Geologisches Landesamt, Mianchen. Woodyer, K.D., 1970. Discussion of "Formation of flood plain lands" by W.C. Carey. Proc. Am. Soc. Civ. Eng., J. Hydraul. Div., 96: HY 3. Woodyer, K.D., 1978. Sediment transport and deposition by the Darling River. Proc. R. Soc. Vic., 90. Woodyer, K.D., Taylor, G. and Crook, K.A.W., 1979. Depositional processes along a very low-gradient, suspended-load stream: The Barwon river, New South Wales. Sediment. Geol., 22: 97-120. Wright, M.D., 1959. The formation of cross-bedding by a meandering of braided stream. J. Sediment. Petrol., 29: 610-615. Wright, V.P., 1982. Calcrete palaeosols from the Lower Carboniferous Llanelly Formation, South Wales. Sediment. Geol., 33: 1-33. Wurster, P., 1964. Geologie des Schilfsandsteins. Mitt. Geol. Staatsinst. Hamburg, 33:140 pp. Wycisk, P., 1984. Faziesanalyse eines kontinentalen Sedimenttroges (Mittlerer Buntsandstein/Hessische Senke). Berliner Geowiss. Abh., Reihe A, 59:126 pp. Yagishita, K., 1980. A note on sand grain orientation in cross-bedding. J. Geol. Soc. Jpn., 8 6 : 1 8 9 - 1 9 4 Yagishita, K. and Jopling, A.V., 1983. Grain fabric of planar cross-bedding formed by lateral accretion, Caledon outwash, Ontario, Canada. J. Geol., 91: 599-606.

ADDENDUM 1 Blakey, R.C. and Gubitosa, R., 1983. Late Triassic paleogeography and depositional history of the Chinle Formation, Southern Utah and Northern Arizona. In: M.W. Reynolds and E.D. Dolly (Editors), Mesozoic Paleogeography of West-Central United States. Soc. Econ. Paleontol. Mineral., Rocky Mountain Section. Rocky Mountain Paleogeography Syrup., 2: 57-76. Bluck, B.J., 1976. Sedimentation in some non-sinuous Scottish rivers. Trans. R. Soc. Edinburgh, 69: 425-456. Bridge, J.S., 1982. Quantitative interpretation of an evolving ancient river system, l l t h Int. Congress on Sedimentology, Hamilton, Ont., p. 149 (abstract). Dresser Atlas, 1980. Relating diplogs to practical geology. Dresser Atlas, 3 M Rep., 7-80 1603:69 pp. Gronemeier, K. and Martini, E., 1973. Fossil-Horizonte im R r t der hessischen Rht~n. Notizbl. Hess. L. Amt. Bodenforsch., 101: 150-165. Harms, J.C., MacKenzie, D.B. and McCubbin, D.G., 1963. Stratification in modern sands of the Red River, Louisiana. J. Geol., 71: 566-580.

70 Hemingway, J.E. and Knox, R.W. O'B., 1973. Lithostratigraphical nomenclature of the Middle Jurassic strata of the Yorkshire Basin of North-East England. Proc. Yorkshire Geol. Soc., 39: 527-535. Mader, D., 1975. Der Siadteil des Oberbettinger Triasgrabens (Westeifel). Erlauterungen zu einer geologischen Karte 1: 25,000. Diplomkartierung (M.Sc. mapping), University of Heidelberg, Heidelberg, 43 pp. (unpubl.) Mader, D., 1979. Stratigraphie und Faziesanalyse im Buntsandstein der Westeifel. Ph.D. thesis, University of Heidelberg, Heidelberg, 293 pp. Monro, M., 1982a. Localised slurry-filled channels within a sandy, braided river system. 21st Annual Meeting of the British Sedimentological Research Group, Liverpool. Monro, M., 1982b. A major channel transverse bar and braid channel sequence from the Fell Sandstone of Northumberland. 21st Annual Meeting of the British Sedimentological Research Group, Liverpool. Ross, G.M. and Donaldson, J.A., 1982. The Bigbear erg: A Proterozoic aeolian sand sea in the Hornby Bay Group, Northwest Territories, Canada. l l t h Int. Congress on Sedirnentology, Hamilton, Ont., p. 68 (abstract). Schlumberger, 1981. Dipmeter interpretation. Volume I--Fundamentals. Schlumberger, New York, N.Y., M-081021:61 pp. Sch~ifer, M., 1976. Der Nordteil des Oberbettinger Triasgebietes (Westeifel). Erl~iuterungen zu einer geologischen Karte 1: 25,000. Diplomkartierung (M.Sc. mapping), University of Heidelberg, Heidelberg, 31 pp. (unpubl.) Slingerland, R.L., 1976. Geometry of trough cross-stratification and implications concerning methods of paleocurrent determination. Geol. Soc. Am., Abstr. with Programs, 8: 270-271. Tewari, R.C. and Casshyap, S.M., 1982. Paleoflow analysis of late Paleozoic Gondwana deposits of Giridih and adjoining basins and paleogeographic implication. J. Geol. Soc. India, 9: 67-79. Tucker, M.E., 1977. The marginal Triassic deposits of South Wales: continental facies and palaeogeography. Geol. J., 12: 169-188. Turner, B.R., 1982. Climatic and tectonic controls on continental depositional facies in the Eastern Karoo Basin, South Africa. l l t h Int. Congress on Sedimentology, Hamilton, Ont., p. 149 (abstracts). Vortisch, W. and Lindstrbm, M., 1980. Surface structures formed by wind activity on a sandy beach. Geol. Mag., 117: 491-496.

ADDENDUM 2 Abbate, E., Bruni, P. and Sagri, M., 1984. The Daban Basin of Northern Somalia: tertiary deposits connected with the Gulf of Aden structure. 5th European Regional Meeting of Sedimentology, Marseille, France, p. 1 (abstract). Arche, A. and Gomez, J.L., 1984. Sedimentology of the Buntsandstein conglomerates between Boniches and Talayuelas (Province of Cuenca, Spain). 5th European Regional Meeting of Sedimentology, Poster Exhibition. Ballance, P.F., 1984. Sheet-flow-dominated gravel fans of the non-marine Middle Cenozoic Simmler Formation, Central California. In: T.H. Nilsen (Editor), Fluvial Sedimentation and Related Tectonic Framework, Western North America. Sediment. Geol., 38: 337-359. Berners, H.P., Hendriks, F., Muller, A. and Schrader, E., 1983. Faktoren-analytischer Vergleich mesozoischer Sedimenttypen der Eifeler Nord-Siad-Zone und vom E-Rand des Pariser Beckens. Jahresber. Mitt. Oberrhein. Geol. Ver., N.F., 65: 143-166. Berners, H.P., Bock, H., Courel, L., Demonfaucon, A,, Hary, A., Hendriks, F., Mi~ller, E., Muller, A., Schrader, E. and Wagner, J.F., 1984. Vom Westrand des Germanischen Trias-Beckens zum Ostrand

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des Pariser Lias-Beckens: Aspekte der Sedimentationsgeschichte. Jahresber. Mitt. Oberrhein. Geol. Ver., N.F., 66: 357-395. Blakey, R.C., 1974. Stratigraphic and depositional analysis of the Moenkopi Formation, southeastern Utah. Utah Geol. Miner. Surv. Bull., 104:81 pp. Blakey, R.C. and Gubitosa, R., 1983. Late Triassic paleogeography and depositional history of the Chinle Formation, southeastern Utah and northern Arizona. In: M.W. Reynolds and E.D. Dolly (Editors), Mesozoic Paleogeography of West-Central United States. Soc. Econ. Paleontol. Mineral., Rocky Mount. Sect., Rocky Mount. Paleogeogr. Symp., 2: 57-76. Blakey, R.C. and Gubltosa, R., 1984. Controls of sandstone body geometry and architecture in the Chinle Formation (Upper Triassic), Colorado Plateau. In: T.H. Nilsen (Editor), Fluvial Sedimentation and Related Tectonic Framework, Western North America. Sediment. Geol., 38: 51-86. Bluck, B.J., 1980. Structure, generation, and preservation of upward-fining braided stream cycles in the Old Red Sandstone of Scotland. Trans. R. Soc. Edinburgh, Earth Sci., 71 : 29-46. Brady III, R.H., 1984. Neogene stratigraphy of the Avawatz Mountains between the Garlock and Death Valley fault zones, Southern Death Valley, California: implications as to Late Cenozoic tectonism. In: T.H. Nilsen (Editor), Fluvial Sedimentation and Related Tectonic Framework, Western North America. Sediment. Geol., 38: 127-157. Conrad, G. and Odin, B., 1984. Le Bassin Permien de Lodrve (Herault). 5th European Regional Meeting of Sedimentology, Marseille, France, Field trip no. 7, Guidebook, 34 pp. Ewijk, E.V., Jongerius, P. and Nio, S.D., 1984. Sediment supply and spatial facies distribution of a tectonically controlled coastal plain alluvial system on the T r e m p / G r a u s Platform, Spain. 5th European Regional Meeting of Sedimentology, Marseille, France, pp. 156-157 (abstract). Glazner, A.F. and Loomis, D.P., 1984. Effect of subduction of the Mendocino fracture zone on Tertiary sedimentation in southern California. In: T.H. Nilsen (Editor), Fluvial Sedimentation and Related Tectonic Framework, Western North America. Sediment. Geol., 38: 287-303. Glennie, K.W., 1983. Early Permian (Rotliegendes) palaeowinds of the North Sea. Sediment. Geol., 34: 245-265. Golia, R.T. and Stewart, J.H., 1984. Depositional environments and paleogeography of the Upper Miocene Wassuk Group, West-Central Nevada. In: T.H. Nilsen (Editor), Fluvial Sedimentation and Related Tectonic Framework, Western North America. Sediment. Geol., 38: 159-180. Haszeldine, R.S., 1981. Westphalian B coalfield sedimentology in NE England and its regional setting. Ph.D. thesis, University of Strathclyde, Strathclyde, 229 pp. Haszeldine, R.S., 1983. Fluvial bars reconstructed from a deep, straight channel, Upper Carboniferous coalfield of Northeast England. J. Sediment. Petrol., 53: 1233-1247. Kerr, D.R., 1984. Neogene continental sedimentation in the Vallecito and Fish Creek Mountains, western Salton Trough, California. In: T.H. Nilsen (Editor), Fluvial Sedimentation and Related Tectonic Framework, Western North America. Sediment. Geol., 38: 217-246. Kleinspehn, K.L., 1984. Cretaceous cross-stratified quartz arenites, Svalbard: fluvial or subtidal sandwaves? 5th European Regional Meeting of Sedimentology, Marseille, France, pp. 234-235 (abstract). Kleinspehn, K.L., Steel, R.J., Johannessen, E. and Netland, A., 1984. Conglomeratic fan-delta sequences (Late Carboniferous-Early Permian), Western Spitsbergen. In: E.H. Koster and R.J. Steel (Editors), Sedimentology of Gravels and Conglomerates. Can. Soc. Pet. Geol. Mem., 10: in press. Laversanne, J., 1976. Sedimentation et minCralisation du Permien de Lod+ve Herault. P h . D . thesis, University of Paris-Sud, Centre d'Orsay, 299 pp. Leo, M.H. and Allen, G.P., 1984. An example of a succession of coarse and fine-grained point bars in the Montllobat Formation (Northern Spain): environmental implications and comparison with a modern analogue, the Garonne River. 5th European Regional Meeting of Sedimentology, Marseille, France, pp. 255-256 (abstract).

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Levey, R.A., 1978. Bedform distribution and internal stratification of coarse-grained point bars, Upper Congaree River, S.C. In: A.D. Miall (Editor), Fluvial Sedimentology. Can. Soc. Pet. Geol. Mem., 5: 105-128. Link, M.H., 1982. Provenance, paleocurrents, and paleogeography of Ridge Basin, southern California. In: J.C. Crowell and M.H. Link (Editors), Geologic History of Ridge Basin, Southern California. Soc. Econ. Paleontol. Mineral., Pac. Sect., pp. 265-276. Link, M.H., 1984. Fluvial facies of the Miocene Ridge Route Formation, Ridge Basin, California. In: T.H. Nilsen (Editor), Fluvial Sedimentation and Related Tectonic Framework, Western North America. Sediment. Geol., 38: 263-285. Mader, D., 1984f. Fluvial sedimentation and palaeosol formation at the margin of the Middle Triassic Lower Muschelkalk sea in Luxembourg. 5th European Regional Meeting of Sedimentology, Marseille, France, pp. 261-262 (abstract). Mader, D., 1985a. Depositional mechanisms controlling accumulation of coarse fluvial conglomerates. In: D. Mader (Editor), Aspects of Fluvial Sedimentation in the Lower Triassic Buntsandstein of Middle Europe. Lecture Notes in Earth Sciences, Springer, Berlin. Mitchell, J.G. and Taka, A.S., 1984. Potassium and argon loss patterns in weathered micas: implications for detrital mineral studies, with particular reference to the Triassic palaeogeography of the British Isles. Sediment. Geol., 39: 27-52. Moore, T.E. and Nilsen, T.H., 1984. Regional variations in the fluvial Upper Devonian and Lower Mississippian (?) Kanayut Conglomerate, Brooks Range, Alaska. In: T.H. Nilsen (Editor), Fluvial Sedimentation and Related Tectonic Framework, Western North America. Sediment. Geol., 38: 465-497. Miall, A.D., 1984. Variations in fluvial style in the Lower Cenozoic synorogenic sediments of the Canadian Arctic Islands. In: T.H. Nilsen (Editor), Fluvial Sedimentation and Related Tectonic Framework, Western North America. Sediment. Geol., 38: 499-523. Odin, B., 1982. Approcbe srdimentologique et structurale du Permien du Bassin de Lodeve (Herault). M. Sc. thesis, University of Marseille, Marseille, 125 pp. Peterson, F., 1984. Fluvial sedimentation on a quivering craton: influence of slight crustal movements on fluvial processes, Upper Jurassic Morrison Formation, Western Colorado Plateau. In: T.H. Nilsen (Editor), Fluvial Sedimentation and Related Tectonic Framework, Western North America. Sediment. Geol., 38: 21-49. Picard, M.D. and Andersen, D.W., 1975. Paleocurrent analysis and orientation of sandstone bodies in the Duchesne River Formation (Eocene-Oligocene?), northeastern Utah. Utah Geol., 2: 1-15. Rawlinson, S.E., 1984. Environments of deposition, paleocurrents and provenance of Tertiary deposits along Kachemak Bay, Kenal Peninsula, Alaska. In: T.H. Nilsen (Editor), Fluvial Sedimentation and Related Tectonic Framework, Western North America. Sediment. Geol.. 38: 421-442. Singh, S.P., 1984. Fluvial sedimentation of the Proterozoic Alwar Group in the Lalgarh graben, northwestern India. Sediment. Geol., 39: 95-119. Vinchon, C. and Toutin-Morin, N., 1984. Corrrlations rrgionales entre les differents ensembles permiens du Sud-Est de la France. Drfinition de leur environnement de drprt. 5th European Regional Meeting of Sedimentology, Marseille, France, pp. 452-453 (abstract). Watchorn, M.B., 1980. Fluvial and tidal sedimentation in the 3000 Ma Mozaan Basin, South Africa. Precam. Res., 13: 27-42.

ADDENDUM 3 Bartow. J.A., 1978. Oligocene continental sedimentation in the Caliente Range Area, California. J. Sediment. Petrol., 48: 75-98.

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Beukes, N.J., 1970. Stratigraphy and sedimentology of the Cave Sandstone Stage, Karoo System. 2nd Int. G o n d w a n a Symp., South Africa, pp. 321-341. Blake, T.F., 1982. Depositional environments of the Simmler Formation in southern C u y a m a Valley, Santa Barbara and Ventura Counties, California. In: R.V. Ingersoll and M.O. Woodburne (Editors), Cenozoic Non-Marine Deposits of California and Arizona. Soc. Econ. Paleontol. Mineral., Pac. Sect., Bakersfield, Calif., pp. 35-50. Casshyap, S.M., 1979. Paleocurrents and basin framework - - an example from Jharia coalfield, Bihar. IV. Int. G o n d w a n a Symp., Calcutta, pp. 626-641. Fernandez, J.C., 1980. Estratificaciones cruzadas deformadas (Triasico del borde sureste de la Meseta Iberica). Estud. Geol., 36: 237-245. Flores, R.M., Hardie, J.K., Coss, J.M., Weaver, J.N. and Van Gosen, B.S., 1984. Upper Fort Union coals in Western Powder River Basin, Wyoming: alluvial-plain deposits. Bull. Am. Assoc. Pet. Geol., 68: p. 477. Good, T.G. and Bryant, I.D., 1984. Fluvio-aeolian sedimentation; an example from Banks Island, N.W.T. In press. Hamlin, H.S., 1983. Carrizo - - Upper Wilcox depositional systems and their relation to updip oil production in South Texas. Bull. S. Tex. Geol. Soc., 23: 17-26. Johnson, S.Y., 1984. Cyclic fluvial sedimentation in a rapidly subsiding basin, Northwest Washington. In: T.H. Nilsen (Editor), Fluvial Sedimentation and Related Tectonic Framework, Western North America. Sediment. Geol., 38: 361-391. Khan, Z.A. and Casshyap, S.M., 1981. A statistical study of reliability of different scales of cross beds as palaeocurrent indicator in the Late Paleozoic fluviatile rocks of Jharia Basin, India. J. Geol. Soc. India, 22: 431-438. Khan, Z.A. and Casshyap, S.M., 1982. Sedimentological synthesis of Permian fluviatile sediments of East Bokaro Basin, Bihar, India. Sediment. Geol., 33: 111-128. Hiller, N. and Stavrakis, N., 1984. Permo-Triassic fluvial systems in the southeastern Karoo Basin, South Africa. Palaeogeogr., Palaeoclimatol., Palaeoecol., 45: 1-21. Legun, A.S. and Rust, B.R., 1982. The Upper Carboniferous Clifton Formation of northern New Brunswick: coal-baering deposits of a semi-arid alluvial plain. Can. J. Earth Sci., 19: 1775-1785. Malmsheimer, K.W., 1968. Zur Sedimentation und Epirogenese im Ruhrkarbon. Forsch. Ber. Nordrhein Westfahlen, 2000:74 pp. Miall, A.D., 1981. Alluvial sedimentary basins: tectonic setting and basin architecture. In: A.D. Miall (Editor), Sedimentation and Tectonics in Alluvial Basins. Geol. Soc. Can., Spec. Pap., 23: 1-33. Miall, A.D. and Gibling, M.R., 1978. The Siluro-Devonian clastic wedge of Somerset Island, Arctic Canada, and some regional paleogeographic implications. Sediment. Geol., 21: 85-127. O c h m a n n , M., 1984. Untersuchung des Ger611bestandes und von Quarzk/Srnern der Solling-Folge (Mittlerer Buntsandstein) im Gebiet der Hessichen Senke und ihre pal~togeographische Ausdeutung. Ph.D. thesis, Univ. Hannover, Hannover, 182 pp. Qidwai, H.A. and Casshyap, S.M., 1975. Sedimentation patterns of the fluviatile Barakar and Motur rocks (Lower Gondwana), Pench Valley coalfield, M.P. Symp. on sediments, sedimentation and sedimentary environments, Delhi Univ., Delhi, pp. 200-222. Rao, J.S. and Sengupta, S., 1970. An optimum heirarchical sampling procedure of cross bedding data. J. Geol., 78: 533-544. Schall, A., 1968. Grund- und Deckgebirge im Bereich tier Mettlacher Saarschleife. Ph.D. thesis, Univ. T'ubingen, Ti~bingen, 93 pp. Smith, N.D. and Smith, D.G., 1984. William River: an outstanding example of channel widening and braiding caused by bed-load addition. Geology, 12: 78-82. Sturm, E., 1971. High-resolution paleocurrent analysis by moving vector averages. J. Geol., 79: 222-233. Van Houten, F.B., Bhattacharyya, D.P. and Mansour, S.E.I., 1984. Cretaceous Nubia Formation and

74 correlative deposits, eastern Egypt: major regressive-transgressivecomples. Geol.' Soc. Am. Bull., 95: 397-405. Wendt, A., 1965. Der Finefrausandstein -- Sedimentation und Epirogeneseim Ruhrkarbon. Forsch. Ber. Nordrhein Westfahlen, 1396:62 pp. Wopfner, H., 1982. Die Trias Australiens, ihre tektonische Stellung und wirtschaftliche Bedeutung. Geol. Rundsch., 71: 949-972. NOTE ADDED IN PROOF Referring to the classification of drainage patterns in alluvial basins into transverse and longitudinal systems relative to the tectonic grain (Miall, 1981, 1984), the Eifel n o r t h - s o u t h depression is in its axial part a particularly well-developed example of the operation of a longitudinal fluvial system flowing downvalley (similarly, also the winds blew downvalley in longitudinal direction). At the margins of the elongated depression zone (especially at the western border in Luxembourg in the Upper Buntsandstein; cf. Mader, 1984a), smaller transverse alluvial systems come in and interfinger with the axial longitudinal belt. The marginal transverse systems, however, are restricted to a narrow seam along the boundary between sedimentary basin and lateral minor source area, and rapidly intertongue to the east with the longitudinal system occupying the predominant part of the depression zone. In contrast, only longitudinal alluvial systems can be recognized in Bavaria, as a consequence of a broad alluvial plain without lateral limitations rather than a palaeomorphologically restricted elongated depositional area. Similar elongated basins with axial longitudinal drainage and marginal transverse flow patterns are reported from various geotectonical settings comprising non-faulted palaeomorphological depression zones, fault-bounded rift grabens and strike-slip basins (for references cf. Mader 1983b, 1984a).