Micromorphology of a Mousterian paleosol in aeolianites at the site Habonim, Israel

Catena 34 Ž1999. 365–384

Micromorphology of a Mousterian paleosol in aeolianites at the site Habonim, Israel A. Tsatskin ) , A. Ronen Zinman Institute of Archaeology, UniÕersity of Haifa, Haifa, 31905 Israel Received 20 May 1997; accepted 25 November 1997

Abstract A paleosol with Mousterian tools in aeolianites at the Habonim site ŽCarmel Coastal plain, Israel. is a complex pedosedimentary sequence which records a succession of soil-forming episodes and stages of coastal dune instability. We identified three strong soils and one accretionary soil within Mousterian pedocomplex via micromorphological techniques, coupled with FTIR and SEMrEDAX. In the lowermost, red sandy soil Žhamra. in Unit IV, decalcification led to the formation of micritic coatings, disrupted by faunal churning, while rubefication resulted in red ferric segregations. Illuviation of ferruginious clay in the form of clay coatings is lacking, probably due to its strong incorporation into the matrix. Redox features were intensified in the pseudogley of the next stage ŽUnit III.. Polyphase calcitic features here indicate that illuviation of clay pre-dates illuviation of micrite and its later recrystallization into sparitic calcite. Further deterioration of drainage conditions and increased accumulation of fine particles led to the formation of vertisol ŽUnit II.. Paleovertisol is characterized by a maximum of clay, stressoriginated microfabric, abundant Mn precipitates and calcitic pseudomorphs. The peak of landscape instability occurred later and is recorded in the upper Unit I, in which micromorphological signs of colluvial and aeolian processes are juxtaposed with various ferric accumulations, associated with gleying. The final episode occurred at a time of climatic instability, devegetation, and probably, a simultaneous groundwater rise in the littoral zone. q 1999 Elsevier Science B.V. All rights reserved. Keywords: Aeolianite; Mediterranean; Paleosols; Micromorphology; Mousterian

1. Introduction Indurated sand dunes chaeological implements )

Žaeolianites. interstratified with paleosols and occasional arŽGvirtzman et al., 1984; Cremaschi, 1990. provide an impor-

Corresponding author. Fax: q972-4-8240493; E-mail: [email protected]

0341-8162r99r$19.00 q 1999 Elsevier Science B.V. All rights reserved. PII: S 0 3 4 1 - 8 1 6 2 Ž 9 8 . 0 0 1 0 1 - 5

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Fig. 1. Location map of the site Habonim and distribution of Mousterian hamra exposures in the Carmel area.

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tant source of paleoclimatic information in the Mediterranean region during the Quaternary. In the Israeli Coastal plain, aeolianites, termed kurkar ŽNeev et al., 1987., contain red sandy loam soils ŽXeralfs., which are termed hamra ŽYaalon and Dan, 1967.. Attempts to correlate the kurkarrhamra sequences with cold and warm oxygen isotope stages of the oceanic sediments assume that kurkar is related to a high sea level, while hamra is related to a regressive stage ŽGvirtzman et al., 1984.. However, Yaalon Ž1967. questioned the interrelatedness of hamra or kurkar to different climatic cycles of the Quaternary. In a recent review paper Goldberg Ž1994. noted that the history of paleoclimatic fluctuations in coastal areas in Israel is still uncertain because of the lack of dating information and a complex nature of hamra soils, which may be either sedimentary or pedogenic in origin. At present, the best way to date kurkarrhamra sequences is with archaeology ŽRonen, 1979. and thermoluminiscence techniques ŽPorat and Wintle, 1994.. Ronen Ž1975. showed that relative ages of various hamras can be assigned on the basis of Ascheulian, Mousterian or Epipalaeolithic archaeological implements which are associated with them. For example, tools of Levallois technique from the hamra exposed in roadcuts of the Haifa–Tel-Aviv highway in the Carmel Coastal plain allowed Farrand and Ronen Ž1974. to define this paleosol as ‘Mousterian hamra’ occurring between two strongly cemented kurkar layers. Recently, a new site at Habonim in the Carmel Coastal plain ŽFig. 1. has been found, in which Mousterian hamra is encompassed between two kurkar Žaeolianite. layers and shows clear catenary changes. According to recent

Table 1 Morphology, RTL dates and properties of a paleosol in the interdune depression at Habonim Unit

RTL date, ka

Munsell notation,dry

Texture, % sand

Structure

Carbonate neoformations, % CaCO 3

Other features

10 YR 7r8

clayey sand, 51%

massive

1 cm lenticular calcrete layer, 42% vs. 16% in bulk sample

shells of of land snails

Kurkar Ia

30"7

Ib

45"10

5Y 5r1

sandy loam, 35%

prismatic

9–12%

remains of snails

II

90"20

5Y 3r1 to 2.5Y 3r2

sandy clay loam, 39%

blocky with superimposed platy, slickensides

carbonate concretions, ca. 5%

scattered Levallois flints

10 YR 4r6

sandy loam, 48%

blocky, few s

2–3%

7.5 YR 4r6

loamy sand, 60%

massive

carbonate druses and pans, 45% vs. 0.8% in bulk sample

III IV

130"33, 107"27

Kurkar

160"40

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radiothermoluminiscence ŽRTL. dates obtained via Vlasov and Kulikov Ž1989. technique, Mousterian hamra at Habonim clearly post-dates oxygen isotope stage 6 ŽRonen et al., in press.. The dates available so far allowed to suggest that the paleosol developed at least since ca. 120 ka through substages 5e–5a of the oxygen isotope scale and probably on. However, the big chronological gap between the lower kurkar, underlying the Mousterian hamra, and the upper kurkar Žsee Table 1. is still controversial. While additional dates are presently in preparation, integrated paleopedological study seems important in assessing the reliability of RTL techniques. Earlier paleopedological studies ŽDan and Yaalon, 1971. showed that morphology, general analytical parameters and catenary relationships between buried hamra and vertisol are all basically similar to the surface soil association in the coastal plain. More recent investigations ŽWieder and Yaalon, 1982. revealed the complexity and polygenetic nature of surface soils in the coastal plain, in particular, that of micromorphological effects of secondary carbonate accumulations. In Mediterranean environments various micromorphological features, particularly those which manifest calcification and clay translocation, have been used to evaluate the evolution of red soils ŽXeralfs and related taxons. in Pleistocene ŽDorronsoro, 1994; Fedoroff, 1997.. However, the potential of micromorphology in unraveling the history of pedogenesis and sedimentation during the development of a hamra of a given age has not yet been fully explored. The aim of this paper is to refine the pedosedimentary history of the Mousterian paleohamra at Habonim. In order to better understand the nature of the Mousterian paleosol, an integrated micromorpholgical approach has been employed. General characterisation, archaeology and preliminary dating of the Habonim site are given in Ronen et al. Žin press..

2. Materials and methods The Carmel coastal plain of Israel is characterized by a Mediterranean climate with cool, rainy winters and prolonged dry summers. The mean annual rainfall is ca. 600 mm, while the potential evapotranspiration reaches ca. 1700 mm. The mean temperature is 288C in August and 138C in January ŽAtlas of Israel, 1970; Orni and Efrat, 1980.. The quarry near kibbutz Habonim is located on a kurkar ridge, 25 m altitude, on the Carmel coastal plain ca. 30 km south of Haifa ŽFig. 1.. The kurkar–hamra sequence is composed of three main layers: Ž1. upper kurkar, 4 m thick; Ž2. hamrarvertisol paleocatena, occupying a shallow depression, about 100 m long in the paleorelief, where an archaeological survey uncovered scattered flint implements of Levallois technique, related to Middle Palaeolithic ŽMousterian. assemblages ŽRonen et al., in press.; and Ž3. lower kurkar, 3 m visible. Field descriptions are based on Soil Survey Staff Ž1975. and the Israeli classification approach ŽThe Classification of Israel Soils, 1979.. Total calcium carbonate was measured by volumetric calcimetry. Particle size was determined by a hydrometer method after dispersion in calgon. The petrographic thin sections were sampled at 20 cm intervals and described according to Bullock et al. Ž1985.. Scanning electron microscope examination of the back-scattered electron images and microchemical determinations by

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EDAX were performed in the laboratories of the Geological Survey of Israel on GEOL 800. Mineralogical analyses, which primarily focused on the calciteraragonite ratio, were made by a Fourier transform infra-red spectroscope ŽFTIR. in the Department of Structural Biology in the Weizman Institute of Science. The radiothermoluminiscence ŽRTL. measurements were taken in the Radiochemistry Laboratory of Moscow State University, following the procedure of Vlasov and Kulikov Ž1989..

3. Paleosol morphology in the interdune depression In the upper part of an ancient dune at Habonim, the Mousterian hamra, occurring between two kurkar layers, is 1.2 m thick and shows signs of truncation. Lateral tracing of this paleosol showed that a 4.5 m thick sequence of morphologically different units occurs in the middle part of a shallow interdune depression ŽRonen et al., in press.. We focused on the detailed morphological and analytical studies of the interdune depression, presuming that the effects of pedogenetical development were better preserved here than on the slopes of paleocatena. The basic characteristics and the results of RTL dates are summarized in Table 1. Four different units ŽI through IV downward. can be distinguished within the interdune depression. The RTL dates ŽTable 1. show strong chronological discrepancies between the upper and the lower units. Hence, their interpretation at present is only tentative, suggesting that the development of the sequence occurred within the timeframe of the early Late Pleistocene, probably related to oxygen isotope stages 5 and 4. The upper Unit I lies immediately beneath the Upper Kurkar. It includes a layer of loose sandy clay Ždesignated as Subunit Ia. and a paleosol with abundant gley features ŽSubunit Ib.. Subunit Ia contains shells of land snails, its lower contact is characterized by narrow, vertical cracks 1–3 cm thick and ca. 50 cm long. A calcrete pan with ca. 40% CaCO 3 Žvs. 16.6% in the background of the layer. is recognized at the top ŽTable 1.. Subunit Ib shows yellow mottles and a halo along the blue-green root traces, apparently as the result of gleying; the amount of sand decreases to ca. 35% compared to ca. 50% in Subunit Ia; remains of land snail shells are common; gradual lower contact. Unit II is recognized as a dark-colored Ž5Y 3r1 to 2.5Y 3r2., non-calcareous, sandy clay loam paleosol, similar to surface vertisols. This is evidenced by a complex juxtaposition of blocky and prismatic structure, by slickensides, as well as iron– manganese and carbonate concretions, stained with black ŽMn. material; Mousterian artifacts are restricted to this unit; gradual lower contact. Unit III includes a partially truncated paleosol, developed under conditions of better drainage. It shows a dark brown to yellowish-brown Ž10 YR 4r6. sandy loam AB horizon, with fewer slickensides than in Unit II. It has a blocky structure, with some platy and angular peds; faint Mn coatings cover ped surfaces. In contrast to Unit II, the amounts of carbonate concretions substantially decrease; gradual lower contact. Unit IV consists of a well developed paleosol morphologically similar to surface hamra. The upper horizon, tentatively designated as ŽA.B horizon, is a 1.0 m thick,

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reddish-brown to strong brown sandy loam; with sharp linear contact, stressed by large carbonate concretions up to 10 cm in size. The BC ca horizon is a 0.7 m thick, friable, brownish Ž10 YR 6r6–6r8. sand; stony carbonate druses and occasional carbonate lenses; abundant burrows of earthworms 1–3 cm thick, filled with red soil material; gradual transition to the lower kurkar bed. Thus, depth functions of morphological properties of the pedogenic sequence in the interdune depression, which laterally replaces ‘Mousterian paleosol’ on the slopes of the ancient dune, show that the sequence is differentiated into discrete pedological units. Hence, Mousterian hamra may be considered a multiphase pedocomplex which was partially eroded from the upper parts of catena. The nature of each pedological episode and their succession in time are discussed in the following sections.

4. Micromorphological features Key micromorphological indicators, which detail the history of pedological development in the interdune depression at Habonim, are discussed below following Bullock et al. Ž1985.. 4.1. Coarser fine material (c r f) characteristics Subangular coarse Ž0.15–0.20 mm. sand, primarily quarts and less feldspar, constitutes the bulk of the soil mass. Calcite allochems Žca. 10%. are found in the upper units. Fine sand fraction Žca. 10 mm. also contains pyroxenes Žfew., hornblende, tourmaline, rutile, epidote, which are more abundant in the deeper units. In lower units, the material is well sorted and crf 10 m m ratio is 1:1. Thin sections from upper units, contain some foraminifera and quartz grains with an indented outline. A strongly disturbed microfabric is strikingly apparent in the uppermost unit I, in which crf 10 m m ratio is close to 1:2. Sorting is poor, and occasionally sandy laminations occur, testifying to intense run-off during accumulation, as was established by Mucher et al. Ž1972.. ¨ 4.2. Microstructure units A very strongly developed prismatic microstructure with a system of parallel, well accommodated planar voids is found in Unit II, which was defined as a paleovertisol in the field. Such a microstructure was reported in surface Israeli vertisols as well ŽYaalon and Kalmar, 1978. and originates as the result of swelling, shear and stress due to fluctuations in water saturation ŽWilding and Tessier, 1988.. Other types of microstructure may complicate the fabric in different samples. In lower units, for example, blocky, partially-welded peds are common. Some microvoids here are less accommodated and occasionally contain poorly preserved clusters of fecal pellets in contorted channels, suggesting earlier bioturbations. In Unit I, the microstructure is particularly complex, possibly due to superimposition of several phases of restructuring. Mesochannels resulting from root network are found together with randomly distributed planar voids.

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Areas of massive microstructure usually intermingle with areas of prismatic microstructure. 4.3. Fabric of the groundmass Overall, strong birefringence of the carbonate-free groundmass in all of the samples is in agreement with a shear-related, strong prismatic microstructure. However, variations in heterogeneity and in the extent of stress-originated birefringence with depth are noticeable. In Unit I, the b-fabric is of striated type. Units II and III exhibit a strial fabric with large birefringent streaks, associated obviously with slickensides and stronger swell-shrink. The sandy soil in Unit IV, as well as partially in Unit III, shows primarily a granostriated type of birefringence. Characteristically, here are 30–40 mm thick discontinuous, ferruginious areas with high birefringence, adhered to sand grains ŽFig. 2c.. At higher magnifications these areas look like platelets of clay arranged in a parallel fashion ŽFig. 2d., the origin of which is controversial. It seems plausible that these features are not just stress-originated features, but initially were illuviated and accumulated as clay coatings which then disintegrated with aging and plastic deformations. Evidence of illuviation of clay in red sandy soils in the Israeli Coastal plain has been reported by Wieder and Yaalon Ž1978.. Illuviation of clay has been also observed on fluviatile sediments in Central Spain ŽDorronsoro, 1994.. However, clay coatings in soils of Mediterranean areas are generally subjected to destruction during shrink-swell and churning by soil fauna ŽReynders, 1972. which are particularly strong in clayey soils ŽFedoroff, 1997.. If so, we can assume that Unit IV soils at Habonim had contained ferruginious clay coatings, which were eventually erased and are no longer preserved as such in well-developed pedogenic fabrics. However, in contrast to lower units, Unit I displays abundant genuine clay coatings, morphologically very well preserved, and discussed in a separate section below. This allows us to differentiate between real clay coatings ŽUnit I. ŽFig. 2a,b. and their probable derivatives in Unit IV and III ŽFig. 2c,d. on higher taxonomic level, i.e., to recognize the latter in the group of stress-originated features. It is important to note that maximum of heterogeneity of the b-fabric is found in Unit III due to uneven impregnation of the groundmass by finely dispersed ferric oxides after fluctuations in redox potential during periods of water saturation and desiccation. 4.4. Coated grains and rounded aggregates Unit I contains well preserved, low-birefringent clay coatings enveloping both quartz Žoccasionally with indented outline. and calcite grains ŽFig. 2a,b.. Occasionally, these coatings appear in the groundmass after being detached from the grain and mechanically contracted. In Unit I, coated grains are found together with uncoated grains, and with rounded aggregates. Rounded aggregates 0.02–0.05 mm thick are recognized within the apedal mass by their lower birefringence and the ooid-like alignment of clay platelets close to their edges. Such features have been reported in colluvial sediments ŽMucher et ¨ al., 1972; Mucher and Morozova, 1983.. In Unit I, they are present alongside microlami¨

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nations of sand in a poorly sorted mass which both suggest strong disturbances during pedogenesis. The genesis of coated grains in Unit I is more dubious. However, taking into account that clay coatings are found in disturbed soil mass with a peak of indented grains and marine allochems of apparently windblown origin, as well as colluviation features, we must admit that Ž1. they are not likely to originate in situ, and Ž2. they are associated with unstable, arid conditions with accretionary type of pedogenesis ŽKemp et al., 1995.. The question that then emerges is whether arid conditions allow for the illuviation of clay in the form found at Habonim. Recently, it has been shown that in semi-arid environments, the illuviation of clay can definitely take place on permeable materials, albeit only to shallow depths ŽCourty and Fedoroff, 1985; Fedoroff and Courty, 1987.. Tarchitzky et al. Ž1984. experimentally demonstrated that during crusting of hamra, the fine material is detached from sand grains and accumulates ca. 0.6 mm below the surface. In calcareous soil materials, which is the case in Unit I, these coatings are strongly adsorbed by sand grains, even when affected by wind erosion ŽWieder and Yaalon, 1978.. It is therefore suggested that the coated grains were transported into the interdune depression at Habonim from upper parts of catena by wind as well as run-off. Both mechanisms involved can explain the coexistence of grains stripped from clay coatings and coated grains. During transportation, birefringence of clay coatings diminishes, while rotation led to the rounding of grains ŽMucher and Morozova, 1983.. This ¨ allochtonous sediment input could have occurred only at the time of desiccation and environmental instability. 4.5. Calcitic pedofeatures All the secondary carbonate accumulations Žincluding a carbonate pan with 46% of CaCO 3 , Table 1. in the paleosol sequence are composed of calcite. However, in aeolianites, as well as in the remains of landsnails from Unit I, traces of aragonite have been detected by FTIR ŽFig. 3.. These findings are consistent with the previous data on the pedogenic crystallization of calcite from littoral sediments ŽMagaritz et al., 1979.. Although aragonite is absent in bulk samples, some thin sections in upper units contain foraminiferas and algae ŽFig. 4a.. The highest abundance of marine allochems, as well as subhedral sparitic calcite, is striking in Unit I. Neoformed carbonate accumulations can be differentiated into two groups: Ž1. depletionrconcentration features and Ž2. nodules. The nodules may be further subdivided into several types, primarily by their crystallinity and polyphase nature ŽWieder and Yaalon, 1974; Courty et al., 1987.. The depletionrconcentration features are ubiquitous, peaking in the upper parts of the sequence. They vary from 30 mm to 200 mm, are weakly or strongly impregnated with Fig. 2. Photomicrographs of fabric features and coated grains; plane polarized light ŽPPL.; crossed polarized light ŽXPL.; scale bar 100 mm. Ža. Coated grains in Unit I composed of angular quartz Žleft. and calcite Žcentre. ŽPPL.. Žb. The same, XPL. ŽC. Well-sorted sand grains in single spaced porphyric related distribution in Unit III ŽPPL.. ŽD. The same, note granostriated b-fabric; thick streaks of strong birefringence adhering to some grains may be considered reworked clay coatings ŽXPL..

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Fig. 3. Infra-red spectra of a hardpan in Subunit Ia Ža., Upper Kurkar Žb., carbonate nodule in Unit II Žc.. Note that a characteristic absorption peak of calcite at 875 cmy1 in Ža. and Žc. is complicated in Žb. by smaller peak at ca. 856 cmy1 of aragonite.

micrite, and occur either around voids or various segregations ŽFig. 4b,d.. In upper units, these features show diffuse boundaries, indicating localized dissolution and reprecipitation. Juxtaposition with ferric features here testifies to recurrent fluctuations in water saturation. In contrast, strongly impregnated, convoluted, and secondarily aggregated calcitic coatings are more common in lower units, indicating the development of a strong leaching profile here, as well as aging in strongly reworked pedogenic fabrics. Depth functions of nodules are even more striking. Lower units show the diversity of nodules in terms of sizes, composition, signs of polygenesis, and later reworking. Micritic and microsparitic nodules up to 100–200 mm in size dominate. Smaller nodules, as well as transitional forms between diffuse segregations and nodules in Units II and IV ŽFig. 4b., suggest their partial dissolution during times of stronger leaching and also disintegration due to biological activity. Wieder and Yaalon Ž1974. also mention fragmentation and rounding of nodules due to churning. Sequence of phases of illuviation is seen in compound nodules in Unit III, in which fragments of clay coatings are intimately mixed within the vesicular areas of strong micritic impregnation. Hence

Fig. 4. Photomicrographs of calcitic and amorphous pedofeatures; plane polarized light ŽPPL.; crossed polarized light ŽXPL.; scale bar 100 mm. ŽA. A carbonate allochem in a poorly sorted matrix in gley soil of Unit I ŽPPL.. ŽB. Disrupted micritic nodules and micriting coatings integrated into the matrix showing complex planar voids in Unit III ŽXPL.. ŽC. Sparitic calcite nodule stained with Mn segregations with diffuse boundary in Unit II ŽPPL.. ŽD. Strongly impregnated Mn nodule enveloped by micritic coating of variable thickness in Unit II ŽXPL..

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clay illuviation here pre-dates the stage of carbonate illuviation. The history of formation of compound nodules consisted possibly of several episodes of successive growth with eventual expansion into the adjacent matrix. Over time calcitic nodules were fractured, in well aerated areas micrite recrystallized into sparite. Tiny ferric segregations accumulated during episodes of higher hydromorphism. In Unit II, large nodules ca. 1 mm in size with sharp boundaries ŽFig. 4c. are impregnated with manganese and ferric segregations. In upper units, nodules originating most likely from illuviation process are gradually replaced by calcitic pseudomorphs after landsnail shells. Pseudomorphs, in average ca. 0.5–0.9 mm in size, incorporate few sand grains, and are stained by ferric oxides, particularly in Unit I. Processes of hydromorphism might have led to frequent dissolution and recrystallization of micrite into sparite. Thus, depth functions of calcite accumulation in the interdune depression at Habonim clearly reveal a trend of changes from conditions of strong leaching towards reduced leaching, i.e., from relatively good to impeded drainage, and eventually to perched water table in Unit I and II. 4.6. Amorphous pedofeatures Amorphous pedofeatures, comprised primarily of Mn and Fe, are indicators of periodic water saturation and the processes of reductionroxidation in the soil mass ŽBouma et al., 1988.. At Habonim, amorphous features peak at the top of the sequence and gradually diminish downward. This implies that reduction and mobilization of iron and manganese under hydromorphic conditions reached a maximum during the final stages of development of Mousterian pedocomplex. However, thin sections also show the variability of different forms of Fe–Mn segregations with depth. For example, diffuse segregations, coatings on walls of channels and intercalations, often juxtaposed with calcitic hypocoatings, are typical in Unit I. This is explained by the movement of reduced substances from the interior of peds to aerated pores when a periodically wet soil starts to dry up. In Unit III, effects of redox processes are revealed in intermingling of areas depleted of iron and areas strongly impregnated by iron compounds in oxidized form Žeffect of seasonal hydromorphism.. Reddish-brown pelletsraggregates are characteristic in Units III and IV, whereas opaque nodules, ca. 1.2 mm in size, sometimes with signs of truncation, primarily occur in the black vertic paleosol of Unit II ŽFig. 4d.. In order to obtain a better understanding of the history of gleying processes at Habonim SEMrEDAX studies of amorphous pedofeatures have been executed. 4.7. Clay concentration features Clay coatings on the walls of pores and channels are completely lacking in all the samples, although slickensides and shiny faces on peds have been observed in the field. This observation in red Mediterranean soils was amply discussed by Fedoroff Ž1997.. Well-preserved clay coatings on sand grains at Habonim have been proposed as a redeposited phenomena. Clay concentration features upon sand grains at the base of the sequence at Habonim, in view of ambiguity of their genesis, are discussed in the section devoted to the type of b-fabric of the matrix ŽFig. 2c,d.. However, fragments of clay

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coatings have been encountered within compound polygenetic carbonate accumulations, testifying that clay illuviation antedates carbonate leaching.

5. SEM r EDAX analyses Back-scattered electron ŽBSE. images by SEM helped to distinguish different mineral phases within the nodules ŽFig. 5. and to define their elemental composition via EDAX. In these ways, the depth functions of amorphous pedofeatures were clarified. For example, comparison of BSE images from Unit I and from Unit II showed substantial differences. In Unit I concentric nodules, similar to tiny Lizegang rings ca. 1 mm in size, show a core and several concentric laminae in the outer rim with high accumulation of Fe ŽFig. 5a.. Since Fe has not been detected in the core area of the nodule, we inferred that the latter is comprised by organic carbon, undetectable by EDAX. In Unit II Žpaleovertisol., somewhat morphologically similar concentric nodules showed a much denser fabric. Concentric laminae, in contrast to the organic rich core, are composed of pure Mn without any admixture of Fe ŽFig. 5b.. Hence, the nodules have originated from impregnation of the matrix by manganese-bearing solutions, as known from vertisols in Israel ŽYaalon et al., 1972.. Nettleton and Sleeman Ž1985. proposed that Mn Žand not Fe. preferentially accumulates in vertisols because reducing conditions were never strong. On the other hand, Mn, which is soluble over a wider Eh-pH range than Fe, accumulates in wetlands ŽBrinkman and Van Diepen, 1990., probably in the presence of microbes as biogeochemical catalysts ŽRobbins et al., 1992.. Taking into account that calcite pseudomorphs peak in the paleovertisol of Unit II at Habonim, we suggest that manganese nodules here were associated with environments conducive for high bioactivity and productivity. BSE images of amorphous pedofeatures in Units III and IV seem quite different from the upper parts of the sequence. Two types are common: opaque, black compound nodules and red pelletsraggregates. Compound nodules ŽFig. 5c. ca. 1.5 mm in size show a sharp mammillated boundary, outlined by cracks, strongly impregnating skeletal grains of the matrix. EDAX detected both Fe and Mn. Brown-red pelletsraggregates, ranging in size from 20–40 mm to ca. 300 mm ŽFig. 5d., appear as rounded segregations unevenly impregnated with Fe alone. There are several cores of incipient concentration, later strongly bound by a ferruginious cohesive mass and assimilated into a larger aggregate. Tiny interconnected cracks are visible ŽFig. 5d.. Although direct mineralogical composition of these red-colored, purely ferruginious features has not yet been undertaken, there is enough evidence to suggest that they consist of hematite. It should be noted that such a type of ferruginization does not seem to be associated with reworking of illuviated clay, as proposed by Fedoroff Ž1997., but rather supports the idea of rubefication of Mediterranean soils proposed by Bresson Ž1974.. Schwertmann and Fitzpatrick Ž1992., who have recently summarized the geochemistry of iron in surface environments, attribute the formation of hematite to a high rate of Fe release from rocks, low organic matter content and higher temperatures during oxidation. Thus, SEMrEDAX clarified the depth functions of amorphous pedofeatures within the paleosol. An upper unit of the palesols primarily contains ferruginous nodules and

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coatings Žprobably with organic carbon., whereas a paleovertisol in the middle of the buried soil contains manganese nodules only. Lower units contain red ferruginuous pelletsrsegregations, presumably of hematite composition. Thus, the peak of gleying with the lowermost redox potential is deduced in the upper Unit I, before burial by encroached sand.

6. Discussion The presented micromorphological data show that the paleosol in the interdune depression at Habonim records a complex sequence of pedogenic and sedimentary processes. Thin sections allow us to detail field observations and genetically classify different soils within the Mousterian pedocomplex. However, these soils are not separated by non-soil sediments, implying overprinting of successive stages during paleopedogenesis. The first pedogenic episode occurred on well-sorted permeable sands and included strong leaching of carbonates ŽUnits III and IV. and reddening of the soil mass. Probably, at the onset massive decalcification led to the accumulation of large carbonate druses in the subsoil. Leaching has led to the accumulation of micritic nodules and coatings, which all underwent transformations during a time of landscape stability, expressed either in the form of recrystallization of micrite or mechanical disintegration by churning. Reddening Žrubefication. of a sandy soil Žca. 60% sand. could have been associated with release of high amounts of iron oxides, which crystallize as finely dispersed, red-colored hematite upon drying, as established by Bresson Ž1974. in the western Mediterranean area. This seems to corroborate by our findings of ferruginized siltrsand-sized pellets in Units III and IV. In surface hamra soils of the Coastal plain, reddening as a recent process ŽDan et al., 1972. has been questioned by oxygen isotope data ŽMagaritz et al., 1981.. Horowitz Ž1979. suggested that reddening of surface hamra occurred during earlier, more humid periods with summer rains, when the climatic belts were shifted south of their present-day position. Ferric oxides, closely associated with clay, are also found in birefringent streaks around sand grains, suggesting that they formed through illuviation. However, clay coatings, as the only true indicators of illuviation, have not been preserved at Habonim. Later, fine-grained materials accumulated Žca. 40% clay in Unit III., and seasonal waterlogging intensified in the paleodepression. A pseudogley, which overlapped the earlier hamra, shows localized depletion of a soil mass from iron compounds. Fragments of coatings Žpapules, according to Brewer, 1964. within compound calcitic nodules suggest that clay illuviation pre-dated illuviation of carbonates. At present, it is not clear whether this indicates abrupt environmental change or fluctuations in precipitation in a Fig. 5. SEM photomicrographs of BSE-images of amorphous pedofeatures. ŽA. Concentric nodule with Fe-rich laminations and, presumably, with organic carbon in the core in Unit I. ŽB. Dense concentric nodule comprised of Mn in Unit II. ŽC. Dense Fe–Mn nodule embedding grains of primary minerals Žgrey—quartz, light— hornblende.. ŽD. Reddish pellet of presumably haematite composition.

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stable climate. However, growth of polyphase calcite nodules into an adjacent groundmass occurred in stages, allowing for partial dissolution, recrystallization of micrite into sparite, and incorporation of ferric diffuse segregations into a growing nodule. The general trend is marked by further accumulation of fines and deterioration of drainage conditions. The next developmental stage ŽUnit II. overprints pseudogley and is characterized by vertisol formation on a more clayey substrate Žca. 50% clay. in the paleodepression. Stress generated microfabric due to swell-shrink in Unit II is consistent with micromorphology of vertisols ŽBlokhuis et al., 1990.. Fluctuations in redox potential due to seasonal water saturation resulted in the formation of abundant manganese features, occasionally juxtaposed with calcitic features. Ferric oxides have not accumulated because of the absence of strong enough reducing conditions. Over time, leaching of carbonates, which was strong during earlier developmental stages, waned. At the end of this episode, calcite pseudomorphs, formed in situ by localized dissolution and precipitation of land snail shells, replaced carbonate illuviation features. In general, paleoenvironments of high biological activity and productivity can be deduced. However, in paleoclimatic terms it is not clear if low infiltrability of clayey parent material of Unit II or increase in paleoprecipitation or both were responsible for the formation of vertisol. It is worth noting that prehistoric tools are associated with soils of this developmental stage. The following stage of development, recorded in Unit I, is entirely different from earlier episodes, because it reflects an accretional pedogenesis, when pedogenic reworking is not strong enough to erase sedimentary fabric ŽKemp et al., 1995.. The suite of micromorphological features in Unit I is rather controversial and difficult to interpret. On the one hand, we have indications of accelerated processes of slope and wind erosion, which are revealed by sandy laminations in poorly sorted matrix, abundance of windblown calcareous littoral allochems, rounded aggregates of low birefringence, and coated grains. As shown above, these features are likely to originate from allochtonous input of coarse and fine materials into the interdune depression at the time of dunal instability, i.e., environmental aridization. On the other hand, micromorphological features of waterlogging and gleying, when redox potential might have dropped to the lowermost values recorded in the given sequence, are at their peak here. These are various ferric and organo-ferric concentric nodules and segregations with diffuse boundaries, often juxtaposed with calcitic hypocoatings. If we assume that a local groundwater rise, rather than a wetter climate, triggered these pedosedimentary changes, we seem to escape the controversy between the two suites of features in Unit I. Gradual environmental aridization might have caused accelerated encroachment of sand inland and buildup of large dunes at the outlets of the wadi. Eventually dunes might have blocked river discharge into the sea and caused increased waterlogging in already existing depressions. The final episode was characterized by a complete modification of local topography, cessation of pedogenesis, ongoing sand accretion and colluviation from the slopes. All these resulted in leveling of the Mousterian paleodepression at Habonim. Intensified aridity led to sand penetration into the cracks on the surface of the gley soil of Unit I. There is little doubt now that a long history of development of Mousterian pedocomplex buried in aeolianites in the Carmel area was controlled by both climatic change

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Žnamely precipitation. and local sea level fluctuations. Unfortunately, no valid evidence exists at present to correlate this micromorphological record with global Late Pleistocene sea level fluctuations. Recent attempts to establish relationships between the accumulation of Holocene dunes in Europe with either marine transgressions or regressions have met with controversy ŽBakker et al., 1990.. Taking into account presently available RTL dates at Habonim ŽTable 1., it is tempting then to relate the developmental stages of Mousterian pedocomplex in the Carmel area, at least, to substages 5e–5a of the global oxygen isotope curve ŽRonen et al., in press.. Interestingly, refined micromorphological data from this pedocomplex in Israeli coastal aeolianites are surprisingly consistent with paleopedological reconstructions of Last Interglacial sensu lato from European loess-soil and coastal sites ŽFedoroff and Goldberg, 1982; Paepe et al., 1990.. Hence, micromorphological evidence from a paleosol at Habonim seems to backup the range of RTL dates obtained thus far.

7. Conclusions An integrated micromorphological study of Mousterian pedocomplex in aeolianites at Habonim provided evidence for refined pedosedimentary reconstructions, presumably, during stage 5 of the oxygen isotope curve Žsee Table 1.. Micromorphology together with SEMrEDAX appears to be no less effective for proxy paleoenvironmental change in Mediterranean dunal areas than it is in loess-soil sequences elsewhere. Our findings show that even welded profiles in aeolianites may be securely subdivided into discrete pedological and sedimentary stages by micromorphology. However, in the Eastern Mediterranean areas, the paleopedological record in aeolianites is difficult to translate into specific paleoclimatic parameters because of the fragmentary nature of paleosols, strong spatial variability, and colluviation. Mousterian pedocomplex at Habonim is micromorphologically differentiated into three strong pedogenic episodes Žlower units. and a weak accretionary soil at the top. Successive development of strong earlier soils from hamra to vertisol testifies to progressive waterlogging and impeded drainage, as well as progressive accumulation of fine particles Žsilt and clay.. Dan Ž1990. developed the hypothesis of constant aeolian influx of the airborne fine particles into Israeli soils. This is difficult to apply to a polygenetic Mousterian pedocomplex without some reservations. It seems more probable that stages of development of discrete paleosols within Mousterian pedocomplex were punctuated with episodes of aggradation and accelerated input of fine particles in changing coastal environments. This is more consistent with the complexity of the micromorphological record at Habonim. Aeolian and colluvial processes substantially accelerated during a transition to a period of landscape instability, which occurred prior to ca. 45 ka, according to RTL dates. Intensified waterlogging at this stage is probably due to a groundwater rise caused by the possible buildup of large dunes at the outlets of the wadi and eventual reworking of local topography. Thus, we hold that pedogenic development of Mousterian hamras also included various sedimentary processes, the intensity of which varied in time as a result of both climatic and sea level fluctuations. At present, however, refined reconstructions of the

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Mousterian pedocomplex are difficult to match with a concrete sea level of Mediterranean. Micromorphological record from Habonim seems to agree with currently available absolute dates which both argue that Mousterian pedocomplex in Mediterranean littoral zone has witnessed numerous environmental changes during early Late Pleistocene.

the the the the

Acknowledgements The research was supported by Faculty of Humanities and Research Authority of the University of Haifa and by Wolfson Family Charitable Trust for A. Tsatskin. We thank Ehud Galili ŽIsraeli Antiquities Authority. and S.A. Laukhin ŽInstitute of Geography, RAN, Moscow. who helped much in the field, and Steve Weiner ŽWeizmann Institute of Science. who kindly provided FTIR facilities.

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