Source rock habitat and hydrocarbon potential of Oligocene Menilite Formation (Flysch Carpathians, Southeast Poland): an organic geochemical and isotope approach

Org. Geochem. Vol. 29, No. 1 3, pp. 543 558, 1998 © 1998 ElsevierScienceLtd. All rights reserved Printed in Great Britain PII: S0146-6380(98)00059-X 0146-6380/98/$- see front matter

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Source rock habitat and hydrocarbon potential of Oligocene Menilite Formation (Flysch Carpathians, Southeast Poland): an organic geochemical and isotope approach J. KOSTER'*, M. K O T A R B A 2, E. L A F A R G U E ~ and P. KOSAKOWSKV 'Department of Petroleum Geology, Institute of Geology and Palaeontology, Technical University Clausthal, Leibnizstr. 10, 38678 Clausthal-Zellerfeld, Germany, 2Department of Fossil Fuels, University of Mining and Metallurgy, AI. Mickiewicza 30, 30059 Krak6w, Poland and qnstitut Fran~ais du P6trole, B,P. 311, 92506 Rueil-Malmaison Cedex, France Abstrae~Geochemical and isotope methods have been used to analyse the hydrocarbon potential and petroleum generation characteristics of the Oligocene Menilite Formation, the most important petroleum source rock in the overthrust part of the Carpathian foreland basin in SE Poland. The data show a large variability in quantity (up to 18% TOC), quality (type II and II/Ill) and carbon isotope composition of the organic matter in samples of different lithology and from different stratigraphic and tectonic settings. These differences reflect distinct sedimentary and tectonic histories of individual subbasins. The maturity in the outer tectonic units is very low (Tmax<420°C, Ro <0.35%) but increases towards the inner nappes and also laterally to the SE. The variability of the kinetic parameters indicates the likely occurrence of multiphase hydrocarbon generation. The Menilite Formation forms a very good source rock in the complex petroleum system of the Carpathian overthrnst belt. © 1998 Elsevier Science Ltd. All rights reserved Key words Carpathians, Oligocene, Menilite Formation, source rock potential, organic carbon content, sulfur content, Rock Eval, stable carbon isotopes, petroleum generation, kinetic modelling, maturity

INTRODUCTION The Carpathians are part of the Alpide orogenic belt and extend from the Czech Republic (Vienna Basin) through Slovakia, Poland and Ukraine to the Iron Gate in Romania. The Carpathian foreland basin is subdivided into two major units: the folded and thrusted flysch belt and the Carpathian Foredeep. Flysch sedimentation took place from Lower Cretaceous to Oligocene. During this time up to 4000 m of sediments were accumulated in the generally southward deepening foreland basin. The Carpathian Foredeep is filled with autochthonous Miocene molasse sediments partly being overridden by the Carpathian nappes (Depowski, 1994). The area investigated is situated in south-eastern part of Poland (E of Jaslo, Fig. 1). Here, the Oligocene Menilite Formation crops out within four overthrust units. From the most internal, southward nappe to the most external one to the north these units are: the Dukla unit, which extends into Slovakia, the Silesian unit, and the Skole unit. The Pre-Dukla (also called Fore-Dukla) unit is distin*To whom correspondence should be addressed. Institute of Chemistry and Biology of the Marine Environment, University of Oldenburg, P.O. Box 2503, D-26111 Oldenburg, Germany. E-mail: [email protected].

guished as a narrow stretch between D~kla and Silesian nappes for tectonic reasons, but shows lithological similarities to the Dukla unit. The Silesian and Skole nappes are partly separated by the narrow Sub-Silesian unit. The Magura unit, the uppermost nappe of the Polish Carpathians, which extends further to the south-west, and the Stebnik unit, which is mainly developed in Ukraine, are not included in this study. In the Oligocene the Alpine/Carpathian foreland basin was a narrow mainly east-west elongated seaway remaining from the subduction of the western part of the Tethys. Palinspastic reconstructions for the Polish sector show that the Carpathian Flysch basin was internally subdivided into N W - S E trending troughs separated by highs at the front of the overthrusts (Unrug, 1979; Ellouz and Roca, 1994). These syntectonically formed sub-basins today represent the Dukla, Silesian and Skole nappes (Fig. 1). The palaeo-highs (or "cordilleras") comprise interrupted and condensed sedimentary sequences of reduced thickness (Garlicka et al., 1989) and correspond to the Pre-Dukla and Sub-Silesian units. Their existence was proposed first on basis of palaeo-current analyses (Ksiazkiewicz, 1960). Especially during the Lower Oligocene large amounts of organic matter were accumulated in fine grained clastic sediments of the Menilite Formation. The Menilite Formation is characterised by dark-

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Fig. 1. Geological sketch map of the eastern part of the Polish Carpathians (modified after Depowski, 1990 and Bessereau et al., 1997) showing the location of outcrops (circles) and wells (squares) studied (see text for abbreviations). The major tectonic units are displayed. Vertically hatched: Pre-Dukla unit (PD); diagonally hatched: Sub-Silesian unit; cross hatched: Miocene sediments resting on the overthrust units; SB: Stebnik and equivalent units; horizontally hatched: Borislav-Pokut unit; black: Pieniny Klippen Belt. grey and black, mostly laminated, carbonate free shales with intercalated chert and siliceous shales. In the Pre-Dukla unit (Fig. 1) thin (up to a few dm) beds of fine grained quartz-cemented sandstones are intercalated within the shales which may represent distal sediments of deep sea fans or contourites. Sandstones of variable thickness occur within the Menilite Formation in all tectonic units. They are interpreted as turbidite sediments of the middle to upper parts of submarine fans. Frequently grey mudstones (non-laminated marlstones) occur together with these sandstones. In the Skole unit the Lower Menilite black shales are associated with locally occurring diatomites, diatomaceous shales and chert (Kotlarczyk and Lesniak, 1990). These sequences contain mud flows indicating a deposition on a basin slope. The Menilite Formation has a variable thickness from a few tens of meters to ca. 300 m. It is subdivided in a lower and upper part divided by the intercalation of sandstones (Kliwa Sandstone in Skole unit, Cergova Sandstone in PreDukla and Dukla units).

At the top of the Upper Menilite Formation intercalations of grey mudstones and turbidite sandstones gradually increase. These so-called Transition Beds lead over to the up to 1200 m thick turbidite sandstones and shales of the Krosno Formation which filled the foredeep basin at the end of the flysch deposition. The Outer Carpathians underwent a strong Neogene tectonic shortening. Calculations based on tectonic modelling yield about 130km shortening in the working area between the border of Pre-Dukla and Silesian units and the foreland (Roure et al., 1993), and at least 180 km for the Western Polish Carpathians (Roca et al., 1995). The time scale for the deposition of the Menilite Formation is approximately resolved only (Fig. 2). The directly underlying Globigerina marlstones are latest Eocene in age (van Couvering et al., 1981). The top of the Menilite Formation is diachronous. This is demonstrated by thin (few cm), laminated Coccolithe limestones (Jaslo limestones) which are regarded to be isochronous horizons occurring at

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Here, we present a detailed study of the source rock potential of the Menilite Formation based on a combined geochemical and isotope approach. To better understand the variability of the Menilite Formation special attention is paid to the facies and stratigraphy of the samples. This study is accompanied by a detailed biomarker study of Menilite shales (K6ster et al., 1998).

Formation EXPERIMENTAL

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Fig. 2. Schematic stratigraphic columns of the Oligocene in the major Outer Carpathian units of SE Poland (after Wieser, 1985; Kotlarczyk and Jerzmanska, 1988; Leszczynski and Malik, 1996; Slaczka, 1996 and Malata, 1997); Dia: intercalated diatomites. different positions within the sequence (Jucha, 1969; Haczewski, 1989). In the Pre-Dukla unit at Rudawka Rymanowska (RR in Fig. 1) the transition into Krosno beds is in the lower part of nannoplankton zone 23, and a time span between about 36 Ma and 34.6-30.5 Ma is assumed for the sedimentation of the Menilite Formation (Vet6 and Het6nyi, 1991). In the Skole unit the sedimentation of the Menilite Formation persisted longer. For the section at Krepak (KR in Fig. 1) a duration until nannoplankton zone 25 is assumed (Kotlarczyk, 1988). The Carpathian Overthrust belt in south-eastern Poland is one of the oldest European petroleum provinces. Commercial oil production started in the 1854. Until the end of 1992, the cumulative production from 71 oil and 17 gas fields discovered in the Carpathian basin was l l . 8 x 1 0 6 t oil and 13.1 × 109 m 3 gas (Depowski, 1994). Recent studies dealing with the petroleum systems, hydrocarbon potential and maturity of the Carpathian overthrust belt in SE Poland (Route et al., 1993; Ellouz and Roca, 1994; Kruge et al., 1996; Bessereau et al., 1997) and Ukraine (Koltun, 1992) demonstrate the importance of the Menilite Formation. Oil/oil and oil/source rock correlation studies based on biological markers have shown that the Menilite shales are the most probable source rock for the majority of Carpathian oils (ten Haven et al., 1993; Bessereau et al., 1997). Further evidence is given by the similarity of pyrolysates of source rocks and oil asphaltenes (Kruge et al., 1991). In most of these studies it has been observed that the Menilite shales are very inhomogenous in geochemical composition and hydrocarbon potential, and display strong facies variations which may have resulted in different types of crude oils generated (ten Haven et al., 1993).

Samples

More than 400 samples were taken mainly from outcrops in the Dukla, Pre-Dukla, Silesian and Skole units (Fig. 1). Additionally some core samples were investigated. Special attention was paid to those samples which were taken from sections allowing an interpretation of the sedimentological and stratigraphic context. The most complete section of the Menilite Formation is found near Rudawka Rymanowska (about 20 km SE of Krosno; RR in Fig. 1). Here, the Menilite Formation is almost continuously exposed in its full thickness of about 300 m in the bed of the Wislok river cutting through the Pre-Dukla unit (Roure et al., 1993). A few km southward the upper part of the Menilite Formation and the Transition Beds occur in good outcrops near Wernej6wka (WE). In Silesian unit samples were collected in the Pod Lasem (PL) outcrop. In Skole unit there are numerous outcrops of the Menilite Formation, however being less continuous. Most samples investigated are taken from outcrops in the vicinity of Rzesz6w near Straszydle (ST), Wyzne (WY) and Hyzne (HY), at Krepak (about 20 km SW of Przemysl; KR), and from cores of a shallow well at Futoma (FU in Fig. 1). Methods

The samples were analysed for their total organic carbon (TOC) and total sulfur (Stot) content using a LECO CS 225 elemental analyser. Based on lithology and TOC data samples were selected for further investigations. Ranges and mean values of TOC and S content for samples from selected sections are presented in Table 1. All data are given as wt%. Rock Eval pyrolysis were carried out on 97 samples using a Delsi Rock Eval II Analyser following standard methods described in detail by Espitali6 et al. (1985) and Peters (1986). Ranges and mean values of Rock Eval data for samples from selected sections are presented in Table 2. The shale samples selected for stable carbon isotope analyses were pulverised and Soxhlet extracted with chloroform. Then asphaltenes were precipitated with petroleum benzine. The asphaltene-free bitumens were further separated into saturated hydrocarbons, aromatic hydrocarbons, resins by

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Source rock habitat and petroleum potential of Menilite Formation column chromatography. Alumina/silica gel (2:1 v/v) columns (0.6 × 20 cm) were eluted with petroleum benzine (distillation range 40 to 45°C), benzene and benzene/methanol (1:1 v/v) to obtain the three fractions of different polarity. Extracted shale samples (after removal of carbonates), bitumens and their fractions were combusted in sealed glass tubes, according to the procedure described by Sofer (1980). The stable carbon isotope analyses were performed using Micromass M M 602C and MI-1201 mass spectrometers. Data are presented in the standard f-notation relative to PDB. Analytical precision is estimated to be ___0.15%o. The Rock Eval d~tta of selected shale samples, and the geochemical and stable carbon isotope composition of their chloroform extracts, bitumen fractions and kerogens are presented in Table 3. The distribution of kinetic parameters was obtained using IFP O P T K I N software to optimise the pyrolysis curves produced by a Rock Eval 5 apparatus. Pyrolysis is conducted on bulk rock samples with nitrogen as carrier gas. Various heating rates from 2 to 25°C/min were applied and a minimum of three experiments has been used to optimise the distribution of kinetic parameters. Then the best fitting kinetic parameters (activation energies E, Arrhenius constants A, and initial petroleum potentials Xio) for the observed $2 pyrolysis curves were calculated. The best adjustment corresponds to the minimum of the error function calculated between measured and observed values. Results of O P T K I N modelling are presented in Table 4. RESULTS AND DISCUSSION

Organic carbon and sulfur content The TOC content in the Menilite Formation strongly depends on lithology. Values for black shales vary widely and can reach more than 18% TOC (Table 1). For the Rudawka Rymanowska (RR) section in the Pre-Dukla unit the mean TOC content of samples from the Lower Menilite Formation is higher than for samples from the upper part (8.6 and 5.3% TOC, respectively). Samples from the uppermost Menilite Formation and the Transition Beds at Wernej6wka (WE) yielded a lower mean TOC content of 3.2% suggesting a general decrease of the TOC content in black shales from bottom to the top of the Menilite Formation of the Pre-Dukla unit. Samples classified as darkgrey shales and claystones give an average TOC content of 2.8%. The highest mean TOC content of black shales from Skole unit (10.2%) was found for samples from Straszydle (ST). These black shales belong to the Lower Menilite Formation and are associated with biogenic siliceous sediments, thus representing a facies association being completely different from

547

the predominantly siliciclastic facies studied in the Pre-Dukla unit. Black shales from other sections in Skole unit contain 8.0 and 6.6% TOC for Hyzne (HY) and Krepak (KR), respectively. The values include data from the Lower and Upper Menilite Formation. The total sulfur data show some scattering. This may partly be due to the fact that most of the samples were taken from outcrops, despite efforts were made to obtain material as fresh as possible. For black shales both from the Skole (ST, HY, KR) and from the Pre-Dukla units (WE, RR, Fig. 1) the trendlines in TOC vs Stot plots are nearly horizontal and give intercepts with the sulfur axis between 1.8 and 2.5% Stot (Fig. 3). Following the interpretation by Leventhal (1983) these C/S relationships show an excess of sulfide and point to a deposition of the black shales under euxinic conditions with pyrite being partly formed in the water column. In contrast samples classified as darkgrey shales and claystones show a clear positive relationship of TOC and Sto t data with a trendline almost through the origin of the diagram (Fig. 3). This would correspond to a "normal marine" oxic carbon sulfur signature (Berner and Raiswell, 1984) and a control of the available iron on the sulfur fixation. Cherts and siliceous shales as well as grey mudstones show low TOC contents (avg. 1.0 and 0.66%, respectively), and low total sulfur contents being slightly higher in the mudstones (avg. 0.55 vs 1.1%; Fig. 3, Table 1). However, the possibilities to interpret these bulk data are limited. Sulfur in the Menilite sedimentary rocks is fixed both as pyrite (according to petrographic observations predominantly in framboidal form) and in high and low-molecular weight organic matter (K6ster et al., 1998). Especially in very immature black shales (e.g. Straszydle) organic sulfur dominates whereas pyrite sulfur prevails in the more mature samples from Rudawka Rymanowska (unpublished own data). The analysis of TOC data for different lithologies and stratigraphic intervals combination with the nearly complete lithological description of the Rudawka Rymanowska profile enables an estimate on the amount of organic matter buried in the Menilite Formation. The approximate proportions of different lithologies are 35% black shales, 15% grey shales, 25% sandstones, 15% grey mudstones, and 10% chert and siliceous shales. Using the mean TOC values from Table 1 and ignoring the low amounts of mainly oxidised organic matter in the sandstones, an average TOC content of 3.5% is calculated for the whole Menilite Formation. More than 80% of the organic matter is present in the black shales and contributions of other lithologies are much less significant. For the Transition Beds with a higher portion of TOC-lean lithologies the average TOC content is 2%. The following conver-

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Fig. 3. Total organic carbon content vs total sulfur content for samples of different lithologies from the Rudawka Rymanowska section (Pre-Dulka unit). Trendlines are shown for euxinic Black Sea (A; Leventhal, 1983) and normal marine sediments (B; Berner and Raiswell, 1984), and for black shales and grey claystones investigated (1 to 3). sion factors for different types of organic matter (Tissot and Welte, 1984, p. 496) were estimated based on Rock Eval data described below: 1.3 for black and siliceous shales, 1.4 for grey shales, and 1.5 for grey mudstones. The calculated average organic matter contents are 4.8 and 2.6% for the Menilite Formation and Transition Beds, respectively. Attempts were made to estimate the original amount of organic carbon deposited in sediments by correcting the TOC values for the amount of carbon that has been consumed by sulfate reduction (Lallier-Verg6s et al., 1993; Littke, 1993; Vet6 et al., 1994). It is assumed that the bacterial reduction consumes two mol organic carbon to produce one mol of reduced sulfur. The samples investigated show a very close correlation of the total sulfur and TOC contents. Based on this correlation an average loss of 23% of the deposited organic carbon is calculated (27 and 16% for samples below and above 7% TOC, respectively). In this calculation a diffusive loss of hydrogen sulfide from the sediment which is estimated to be up to 45% (Vet6 et al., 1994) and other losses of organic carbon (e.g. due to methanogenesis) are not considered. As shown later the loss of organic carbon due to maturation is low for the samples studied and has been neglected. To estimate the average rate of deposition of organic matter an approach was made for the Rudawka Rymanowska section similar to the calculations by Vet6 and Het6nyi (1991). Only the data for black and grey shales, chert and siliceous shales were included, but not sandstones and grey mudstones which are considered to be redeposited. The

average organic carbon content of the shales under consideration of their portion within the section is 5.9% (or 7.8% organic matter). With the same approach as above the average content of originally deposited organic carbon in autochthonous sediments is 7.2% TOC or correspondingly 9.6% organic matter. The cumulative shale thickness of 180 m (60% of 300 m total thickness of the Rudawka Rymanowska section), and a time span of 2.75 Ma (mean between minimum and maximum values according to Vet8 and Het6nyi, 1991) yield an avg. sedimentation rate for the shales of 65 m per Ma. Using a rock density 2.55 g/cm 3 (Vet6 and Het6nyi, 1991) the average rate of organic carbon accumulation becomes 12 x 106 g TOC per m 2 per Ma (or 15.6 x 106 g organic matter per m 2 per Ma). This is a conservative estimate as the overall loss of organic carbon is supposed to be 23% only. The result is in the same order of magnitude as the 10.8 x 106g TOC per m 2 per Ma estimated by Vet6 and Het6nyi (1991) who used a TOC content of 3.33% (average of seven shale samples) and considered several scenarios of postsedimentary carbon losses. An extrapolation into other sub-basins of the Carpathian Flysch basin is not feasible regarding the variation in thickness and facies.

Rock Eval pyrolysis The Rock Eval maximum temperature (Tmax) is a good indicator for the thermal maturity of the Menilite Formation, despite a certain dependence on the type of organic matter should be expected. Vitrinite reflectance measurements on selected samples generally confirm the Tmax data. Especially

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the very immature samples show a rather broad distribution of reflectance data. This is due to the presence of recycled vitrinite often being only slightly more mature than vitrinite considered to be representatiw for the maturation level of the samples. Samples from the major part of the Skole unit are immature with Tmax values ranging from 400 to 418°C (Fig. 4). Correspondingly, the vitrinite reflectance is between 0.3 and 0.35% Ro. Higher temperatures around 425°C were found only for samples from a section near Mrzygldd (MG in Fig. 1) situated close to the southern border of the nappe. In the largest parts of the Silesian unit Tm,x values of outcrop samples are in the range of 425 to 430°C. In the Pre-Dukla unit, samples from Wernej6wka (avg. Tma× 437°C, and Ro 0.58%) are more mature than those from Rudawka Rymanowska section (avg. Tm~x 430°C, and Ro 0.40%). In Pre-Dukla and Dukla units maturity changes also laterally. Including published maturity data (Kruge et al., 1996; Bessereau et al., 1997) an increase from an immature level in the NW (Tmax<430°C, about 0.4% Ro) to mature and overmature stages in the SE is evident.

The difference in maturity between the Skole nappe and the more southward situated units is also reflected by the diagenesis of clay minerals. In Skole unit smectite is the dominant clay mineral. In the Pre-Dukla unit (e.g. Rudawka Rymanowska section) illitisation (Hower et al., 1976) has proceeded and illite-dominated mixed-layer minerals prevail (K6ster, unpublished data). The low maturity of organic matter in most of the parts of the Skole and Silesian units within the working area shows that these units did neither undergo deep pre-tectonic (sedimentary) nor tectonic burial due to the Neogene overthrusting (Bessereau et al., 1997). From the continuous increase of Tmax values in wells penetrating complex tectonic structures, Bessereau et al. (1997) concluded that the present-day situation is mainly the result of post-tectonic maturation. This is also assumed for the narrow, tectonically complex PreDukla unit where clear maturity differences are observed in neighbouring tectonic structures (RR and WE sections). Nevertheless, it is likely that pre° tectonic thermal history is responsible for the maturity differences of the Menilite Formation

Fig. 4. Maturity distribution for the Menilite Formation within the area investigated. The boxes show Rock Eval Tm~x(in °C) and vitrinite reflectance (in % Ro) data. Core samples are indicated in italics. Data from Kruge et al. (1996) and Bessereau et al. (1997) are added.

551

Source rock habitat and petroleum potential of Menilite Formation occurring laterally within the inner tectonic units investigated. In general the "cold" Neogene overthrusting advanced from internal parts towards the foreland (Roure et al., 1993). In the Ukraine, where the Menilite Formation is deeply buried to depths more than 5700 m, the pre-tectonic maturation level is preserved in the upper 4000 m and maturity is controlled by present day temperatures in the deepest part only (Koltun, 1992). Besides a deeper sedimentary burial as suggested by Bessereau et al. (1997) an increased heat flow in the internal units of the Carpathian basin has to be taken into consideration. The centres of magmatic activity were situated mainly in Slovakia and Hungary, and volcanism is documented by Oligocene tuff horizons, andesite dykes in Paleogene flysch near the contact of Magura nappe and Klippen belt, and Miocene andesites and basalts within the Moravian Flysch and Pienides in Poland (Mahel, 1978). Present-day heat flow in the whole western Carpathians (Czech Republic, Poland, Slovakia and Ukraine) strongly increases from the outer to the inner zones reaching a maximum in the Neogene basins of eastern Slovakia and Hungary (Cermfik, 1979a,b; Cermfik

and Hurtig, 1979; Majorowicz and Plewa, 1979). Interestingly, isolines of heat flow are oblique to the nappe structures in the area investigated (Cerm6,k and Hurtig, 1979; Majorowicz and Plewa, 1979). Rock Eval pyrolysis yielded a wide range of hydrogen indices (HI) from 15 to 790 mg hydrocarbons/g TOC (Table 2, Fig. 5). To properly interpret these data the lithology, stratigraphic position and maturity of the samples has to be taken into account. Oxygen indices (OI), which are often difficult to assess (Peters, 1986), are reliable, because carbonate is absent or very low in the investigated samples (except in grey mudstones). The variation of HI values for different lithologies is demonstrated for 45 samples from the two sections in the Pre-Dukla unit (Rudawka Rymanowska and Wernejdwka; Fig. 5). Black shales from Rudawka Rymanowska show high HI (452 to 666mg HC/g TOC) and low OI values (< 20 mg CO2/g TOC, with one exception). No significant difference has been found between samples from the lower and upper parts of the Menilite Formation. Even higher hydrogen indices were found for cherts and siliceous shales. Grey shales

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and claystones show a wider range of HI values. Grey mudstones yield less than 200 mg HC/g TOC and slightly increased OI values up to 60 mg CO2/g TOC. Black and brown organic rich sediments with TOC contents between 5.7 and 8.6% are also intercalated in the Eocene sequence (Hieroglyphic beds) underlying the Menilite Formation and Globigerina marlstones at Rudawka Rymanowska (Table 1). In contrast to the Menilite black shales the two samples analysed by Rock Eval show significantly lower hydrogen indices close to 300 mg/g TOC. This is in agreement with HI values < 300 mg HC/g TOC found for "Sub-Menilite shales" by Bessereau et al. (1997). Based on sedimentological observations Leszczynski (1994) interpreted these dark mudstones as low-density turbidites. Menilite black shales from Wernej6wka yield slightly lower HI values than black shales from Rudawka Rymanowska, which may be explained by the higher maturity of this section. In case of black shales from the Skole unit a clear difference can be made between samples from the lower and upper parts of the Menilite Formation (Fig. 5). The Lower Menilite black shales yielded HI values from 367 to 718 mg HC/g TOC, whereas values below 300 mg HC/g TOC were found for the Upper Menilite Formation. The differences in HI values without significant increase in the oxygen index between the two data sets is not explained by mixing of two end members. Petrographic studies of the samples did not identify a possible end member with both low and O1 values. Only within these two data sets a slight increase of OI values with decreasing HI is observed which can be interpreted either as a mixing trend of different types of organic matter or by oxidation (Kenig et al., 1994). The oxygen index of samples from the Skole unit is significantly higher than for Pre-Dukla samples probably due to the lower maturity. The correlation between TOC and $2 (Langford and Blanc-Valleron, 1990) shows that a matrix sorption effect does not occur. The Rock Eval data (except for few outliers identified) are reliable to characterise the organic matter and samples are not significantly affected by weathering in the outcrops. The production indices [defined as the portion of thermally extractable, already generated hydrocarbons of the total of hydrocarbons extracted and generated upon pyrolysis; S 1 / ( S 1 + $2)] are generally very low ( < 0.08) for samples from Skole and Silesian units, and for samples from Rudawka Rymanowska as expected for rocks prior to oil generation. Samples from Wernej6wka which are slightly more mature (avg. Tm~x 437°C) contained a little higher portion of generated hydrocarbons (avg. production index 0.17) indicating the onset of hydrocarbon generation.

The facies differences within and between the Carpathian flysch sub-basins are reflected by the type of organic matter as revealed by Rock Eval pyrolysis. In the Skole basin black shales of the Lower Menilite Formation are associated with diatomaceous sediments. They may represent sediments deposited on the slopes either of the foreland or a tectonic ridge. Such areas can be (temporarily) starved from clastic input (Ori and Friend, 1984) so that mainly biogenic sediments accumulated and black shales with high hydrogen indices were deposited. Mudflows and slumps indicate that the sediments were partly redeposited downslope. Later the Skole basin obviously came under the influence of stronger clastic input with the formation of hydrogen-poor black shales of the Upper Menilite Formation containing larger amounts of recycled organic matter (K6ster, unpublished petrographic data). Lowering of hydrogen indices may also occur when organic rich sediments deposited on the shelf are transported and redeposited in an oxic water column. In present-day turbidites on the Madeira abyssal plain organic matter became depleted in hydrogen from about 600 to ca. 300 mg HC/g TOC during transport. Further oxidation reduced the hydrogen index to ca. 50 mg HC/g TOC in oxidised turbidite sediments (Cowie et al., 1995). The differences between the black shales from Skole and Pre-Dukla units result from a generally different sedimentation history in these sub-basins. During Eocene the organic matter in the Pre-Dukla basin first accumulated at shallower sites, eventually under oxygen minimum zone conditions, and then was redeposited and oxidised within the basin (Leszczynski, 1994). After deposition of the Globigerina marlstones at the Eocene/Oligocene boundary, the sedimentary regime changed and mainly autochthonous hydrogen-rich organic matter was deposited in pelagic black shales under anoxic conditions. At least temporarily an euxinic water column extended into the photic zone (see K6ster et al., 1998). This change could be triggered by a reduction of the deep water circulation (Ricou et al., 1986) resulting from drop of the sea level which restricted the connection with the ocean. Occasionally interrupted by the input of submarine fan sediments, this type of shale sedimentation persisted in the Upper Menilite Formation until the basin finally was filled by the Krosno beds which contain low amounts of hydrogen-poor organic matter only (Bessereau et al., 1997). Indirectly, the concentration of sedimentary organic carbon could be enhanced by the lack of carbonate probably due to sedimentation below the carbonate compensation depth. It has to be noted again that the top of the Menilite Formation is diachronous (Jucha, 1969; Haczewski, 1989) and consequently the sedimentation of the Upper Menilite Formation ceased ear-

Source rock habitat and petroleum potential of Menilite Formation lier in the inner units than in the outer Skole unit (Decker and Peresson, 1996).

STABLE

CARBON

ISOTOPE

COMPOSITION

Fourteen Menilite shale samples from the PreDukla, Silesian and Skole units were analysed for the stable carbon isotope compositions of the bitumen, its fi'actions (saturated and aromatic hydrocarbons, resins and asphaltenes) and the kerogen. The stable carbon isotope ratios (~13C values) are shown in Table 3. Most samples from Pre-Dukla and Silesian units show very similar carbon isotope compositions with differences < 1.2%o only (Figs 6

553

and 7). The 613C values of the Wernej6wka sample are slightly higher by 0.6 (kerogen) to 1.4%o (resin fraction). Saturated hydrocarbon fractions are most depleted in 13C (range from -28.7 to -26.7%o), and kerogens are most enriched (-26.9 to -25.4%o). The differences in stable carbon isotope ratios (613C) among samples from Skole unit are much larger (3.5 to 5.2%o). Saturated hydrocarbons range from -33.6 to -27.3%0 and kerogens are from -28.8 to -25.4%0. Shapes of isotopic curves (Fig. 6) and Sofer's correlation between 613C values of saturated and aromatic hydrocarbon fractions (Fig. 7) show that organic matter accumulated within Menilite

a

SAT

ARO

RES

ASPH

KER

--e- Krepak KR93-15 --c-- Straszydle St93-08

~

-34

~

/[

--

FWYt:meagE3;~:veraae, utoma E2 (a erage) -33

-32

-31

\

-30

~) "X'e -29

-28

r~ -27

~

-26

I ]

[ -25

-24

a'3c 0oo) SAT !

b

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-34

• • •

Rudawka Rym. RR92-39 Rudawka Rym. RR92-67 Rudawka Rym. RR92-134 Wernej6wka WE92-59 --o- Pod Lasem X/B Pod Lasem IX/B h

i

i

i

i

i

-33

-32

-31

-30

-29

-28

-27

i

i

-26

-25

-24

5'3c f/oo) Fig. 6. Carbon isotope type curves (after Stahl, 1978) for extract fractions of Menilite black shales: (a) Skole unit and (b) Pre-Dukla and Silesian units. Note that two samples from the Lower Menilite Formation are up to 5%0 depleted in 13C compared to other Menilite shale samples.

554

J. K6ster et al.

20

S

terrestrial

~" -25

"I'~

/

'~ -30

J / /

o

~

X

J J

algal

Carpathianoverthrustoils (from ten Havenet al. 1993)

y/ / /

/

.

Pro-Ouk,a

•

Silesian Skole

-35 -35

' i-30 -25 (~13Cof saturated HC (%0)

-20

Fig. 7. Carbon isotopic composition of saturated vs aromatic hydrocarbon fractions. Lines are separating marine from terrestrial oils (after Sofer, 1984). Formation belongs to two isotopically different groups. The first group comprises most samples from Skole, Silesian and Pre-Dukla units. A second, isotopically lighter family is represented by two samples from the Lower Menilite Formation in Skole unit (KR-93-15 and ST-93-08; Table 3, Figs 6-8). The Menilite Shale samples of the first group show a trend of decreasing 613C values of bitumens, 800

saturated hydrocarbons, aromatic hydrocarbons, asphaltenes and kerogen with increasing apparent hydrogen content (hydrogen index) of the organic matter (Fig. 8). This can be explained by the admixtures of various amounts of isotopically heavier, hydrogen depleted organic matter of probably terrestrial origin. Alternatively, a stronger, selective degradation of hydrogen-rich and isotopically light organic matter during transportation or settling through an oxic water column may be the cause for the variations observed. Organic matter depleted in 13C by about 3 to 6%0 found in the two samples of group 2 is apparently restricted to the Lower Menilite Formation in Skole unit. This depletion in 13C is also observed for individual biomarkers of various biological origin (K6ster et al., 1998). As the samples show high hydrogen indices, the by far largest part of the organic matter is likely to be autochthonous. It is likely that isotopically lighter carbon source was involved in the biosynthesis of biomass. Isotopically light CO2 can be derived from enhanced recycling of organic matter in the water column (Lewan, 1986). Methane derived from bacterial CO2 reduction (Whiticar et al., 1986) is another source for carbon extremely depleted in 13C. By methane oxidation isotopically very light CO2 can be added to the system and might be utilised by primary producers of organic matter. Evidence for this possibility 800

a

700

700

[]

b

[]

600

600

e

500

500

6" 400 O

400

0••

300

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-ro)

200

0

-34

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800

--

700

c

100

I

I

I

I

-32

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I

I

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C

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700

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n []

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600

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500

500

400

400

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0

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Kerogen

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300

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0

600

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300

300

200

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-26

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Aromatic HC I

I

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#3c (Otoo)

Fig. 8. Carbon isotope composition of kerogens, asphaltenes and extract fractions vs Rock Eval hydrogen index. Squares: two samples from Skole unit, Lower Menilite Formation; open circles: samples from Futoma (E2, Skole unit); black dots: other samples (see Table 3).

-24

Source rock habitat and petroleum potential of Menilite Formation is provided by the occurrence of biomarkers most likely derived from methanotrophic bacteria in these samples (K6ster et al., 1998). The similar stable carbon isotope composition of investigated bitumen fractions and oils accumulated within Carpathian flysch strata, especially in Kliwa

Skole unit

500

Krepak KR93-08 A = 5.269E+13 s -1

400

o

a

200

20C

100

10C

_,,B._ 48 48 50 52 54 56 58 60 62 64 66 68 70 72

O.

E

100

Dukla unit

too[

46 48 50 52 54 56 58 60 62 64 66 68 70 72

Straszydle ST93-08 A = 3.966E÷14s -t

_.it_

44 46 48 50 52 54 56 58 60 62 64 66 68 70 72

b

L

0 44

0

Rudawka Rym. RR92-39 A= 5.355E+1~3s -~

e

40C 30(]

500 / Krepak 4001 KR93-15 A = 1.940E+14s -t 300[

Pre-Dukla unit

50C

E c

sandstones intercalated within Menilite Formation in Skole unit (Fig. 7) indicate that petroleum source rocks are connected with the first family of bitumens (derived from type II and'mixed II/III kerogens). Shales containing organic matter of type II and I/lI belonging to the first group are very imma-

300

0 44

Komancza L. KL91-03

f

fill

2001100[

A~=2.248E+15S -I

C 0" 44

20C

46 48 50 52 54 56 58 60 62 64 66 68 70 72

~°°I~ g 4001

I

Tylawa TY91-12 A = 1.747E+14s -~

I 3001" 44 46 48 50 S2 54 56 58 60 62 64 66 68 70 72

500 / Brzegi Dolne

400[ BD461

d

A = 3.601E+14 s- 1

3001"

44 46 48 50 52 54 56 58 60 62 64 66 68 70 72

2°° 1L

Activation energy (kcal/mol)

100

0 44

555

46 48 50 52 54 56 58 60 62 64 66 68 70 72

Activation energy (kcallmol) Fig. 9. Distribution of activation energies obtained from Optkin kinetic modelling: (a)~-(d) Skole unit; (e) Pre-Dukla unit; (f) and (g) Dukla unit; A: pre-exponential factor in s - .

556

J. K6ster et al.

ture. A significant contribution to Carpathian oils is so far not observed despite their very good potential to be a petroleum source rock.

O p t k i n data

As already recognised from Rock Eval data, the results of kinetic modelling presented in Fig. 9 illustrate the heterogeneity of organic matter quality of shales from the Menilite Formation. Four very immature samples (Tmax<420°C) from the Skole unit show broad distributions of activation energies. Three of them [Fig. 9(b) (d)] have high hydrogen indices (559 to 718 mg HC/g TOC) and contain predominantly type II marine organic matter which leads to a maximum of activation energy of 54 kcal/ mol. The black shale from Krepak with a hydrogen index as low as 242mg HC/g TOC [Fig. 9(a)] yielded low initial petroleum potentials and a distribution of activation energies with a maximum of 52kcal/mol which is unexpectedly low for the mixed organic matter of type II/III supposed to be present in this sample. The three samples investigated from Pre-Dukla and Dukla units are more mature (Tmax ca. 430°C) compared to the samples from Skole unit but did not reach the principal phase of petroleum generation. The distributions of activation energies [Fig. 9(e)-(g)] are more narrow, but maximum energies varying considerably between 52 and 58 kcal/ mol. The distributions of activation energies are apparently strongly influenced by maturity. Rock Eval data indicate that the very immature organic matter in Skole samples contains more oxygen than the organic matter in samples from Pre-Dukla unit (see above, Fig. 5). Analysis of the sulfur speciation (K6ster, unpublished data) show that sulfur is mainly organically bound in the shales from Skole unit, whereas Pre-Dukla- and Dukla samples contain predominantly pyrite sulfur. This corresponds to the high amount of organic sulfur compounds and macromolecularly sulfur-bound biomarkers in Skole samples in contrast to low concentrations of thermally stable organic sulfur compounds found in a black shale from Rudawka Rymanowska (K6ster et al., 1998; K6ster et al., 1995). Rock Eval oxygen indices show that samples from Skole unit generally contain more oxygen in the organic matter compared Pre-Dukla samples. It is most likely that the presence of S- and O-heteroatoms in the organic matter contained in samples from Skole unit is responsible for the broad distribution of activation energies. Additionally, variable mixtures of terrestrial material organic matter as well as slight maturity differences may be responsible for the variations in kinetic parameters, but a relation to maximum activation energies is not evident.

CONCLUSIONS The quality and quantity of organic matter in the Menilite shales varies strongly with lithology. The distribution of organic matter in black shales yielding high and low hydrogen indices differs also between the Carpathian sub-basins. Menilite black shales have high petroleum potential (type II kerogen) in the Pre-Dukla zone throughout the section. In contrast, organic matter in shales from the Skole unit display strong differences between the lower (high HI) and upper (low HI) part of the Menilite Formation. The accumulation of hydrogen-rich organic matter began with the deposition of the Menilite Formation. The variations in quality and isotope composition of organic matter are explained by the individualisation of the Carpathian sub-basins displaying different sedimentary and tectonic histories. This is of help to understand the distribution of petroleum potential within the Polish part of the Carpathian basin. It suggests a control rather by processes within the sub-basins (tectonic subsidence, sediment supply by uplift of ridges) than by external factors, e.g. global sea level changes. As also concluded in other studies the Menilite Formation is a very good petroleum source rock. In outcrops the Menilite Formation is immature in most parts of the area investigated and has reached the oil window only in the eastern parts of the internal units. Further studies are required to estimate the role of an increased heat flow in this area. A general consequence of the variable organic matter quality and the differences in the distribution of the kinetic parameters is the likely occurrence of multiphase hydrocarbon generation. Each organic matter type may release its hydrocarbons at different periods. Therefore, it is necessary to estimate the functioning of each petroleum system separately for a good assessment of the hydrocarbons generated in the different plays in the Carpathian overthrust belt. The petroleum system in the Carpathians suffers rather from the small size of reservoirs and the complexity of their tectonic and thermal history than from good and mature source rocks. The study partially received financial support by grants from the German Research Foundation (DFG), from the Federal Ministry of Education, Science, Research and Technology (BMBF) and the Polish Committee of Scientific Research in frame of a Polish German co-operation agreement, and from partnership funds of the Technical University Clausthal and University for Mining and Metallurgy in Krak6w. Help in analytical work was provided by A. Schulz (Technical University Clausthal), A. Kowalski, T. Kowalski and D. Wieclaw (Department of Fossil Fuels, University of Mining and Metallurgy, Krakow). Logistic support and permission to take core samples by enterprises of the Polish petroleum industry at Jaslo and Krosno is gratefully acknowledged. Specially thanks go to Dr. A. Acknowledgements

Source rock habitat and petroleum potential of Menilite Formation Zubrzycki for his assistance during field work in the Carpathians. The authors thank J. Francu (Czech Geological Survey, Brno) and an unknown reviewer for their constructive comments. REFERENCES

Berner, R. A. and Raiswell, R. (1984) C/S method for distinguishing freshwater from marine sedimentary rocks. Geology 12, 365-368. Bessereau, G., Roure, F., Kotarba, M., Kusmierek, J. and Strzetelski, W. (1997) Structure and hydrocarbon habitat of the Polish Carpathians. In Structure and Prospects of Alpine Basins and Forelands, Memoir 2, Eds P. A. Ziegler and F. Horvfith. Peri-Tethys Memoires du Museum National d'Histoire Naturelle Paris, 170, 343 373. Ed. du Museum, Paris. Cermhk, V. (1979a) Heat flow map of Europe. In Terrestrial Heat Flow in Europe, Eds V. Cerm~k and L. Rybach, pp. 3-40. Springer, Berlin. Cerm~k, V. (1979b) Review of heat flow measurements in Czechoslovakia. In Terrestrial Heat Flow in Europe, Eds V. Cerm~k and L. Rybach, pp. 152-160. Springer, Berlin. Cerm~k, V. and Hurtig, E. (1979) Heat Flow Map of Europe. Springer, Berlin. Cowie, G. L., Hedges, J. I., Prahl, F. G. and De Lange, G. J. (1995) Elemental and major biochemical changes across an oxidation front in a relict turbidite: An oxygen effect. Geochimica Cosmochimica Acta 59, 33-46. Decker, K. and Peresson, H. (1996) Tertiary thrusting in the Alpine-Carpathian-Pannonian system: links between thrusting, transform faulting and crustal extension. In Oil and Gas in Alpidic Thrustbelts and Basins of Central and Eastern Europe, Eds G. Wessely and W. Liebl. EAGE Special Publications 5, 69 77. Geological Society, London. Depowski, S. (1990) Bituminous shales deposits. In Geology of Poland. Vol. VI. Mineral deposits, Ed. R. Osika, pp. 75-77. Wydawnictwa Geologiczne, Warszawa. Depowski, S. (1994) Poland/Polen. In Regional Petroleum Geology of the WorM, Part I, Ed. H. Kulke, Beitrdge zur Regionalen Geologie der Erde, Vol. 21, pp. 367-376. Gebr. Borntraeger, Stuttgart. Ellouz, N. and Roca, E. (1994) Kinematic reconstruction of the Carpathian fold belt and adjacent areas since Cretaceous: a quantitative approach. In Peritethyan Platforms. Proceedings 1FP-Eurotethys International Conference, Arles, 1993, Ed. F. Roure, pp. 51 58. Technip, Paris. Espitali+, J., Deroo, G. and Marquis, F. (1985) La pyrolyse Rock-Eval et ses applications. Premier partie. Revue de l'Institut Fran~'ais du P~trole 40, 563 579. Garlicka, I., Gucik, S., Oszczypko, N., Rylko, W., Zajac, R., Zytko, K., Elias, M. and Mencik, E. (1989) Columnar Cross Sections of the Western Outer Carpathians and Their Foreland (1:500000). Panstwowy Instytut Geologiczny, Warszawa. Haczewski, G. (1989) Coccolith limestone horizons in the Menilite-Krosno Series (Oligocene, Carpathians)identification, correlation and origin. (In Polish with extended English summary). Annales Societatis Geologorum Poloniae 59, 435-523. Hower, J., Esslinger, E. V., Hower, M. E. and Perry, E. A. (1976) Mechanism of burial metamorphism of argillaceous sediments: 1. Mineralogical and chemical evidence. Geological Society of America Bulletin 87, 725 737. Jucha, S. (1969) Lupki jasielkie, ich znacznie dla stratigrafii i sedimentologii serii Menilitowo-Krosnienskiej (Karpaty fliszowe). Les Shistes de Jaslo, leur importance

557

pour la stratigraphie et la s6dimentologie de la S6rie M6nilitique et les Couches de Krosno (Carpathes flyscheuses). (In Polish with French summary), Prace Geologiczne 52, 128. Kenig, F., Popp, B. N. and Summons, R. E. (1994) Isotopic biogeochemistry of the Oxford Clay Formation (Jurassic), U.K. Journal Geological Society London 151, 139 152. Koltun, Y. V. (1992) Organic matter in Oligocene Menilite Formation rocks of the Ukrainian Carpathians: palaeoenvironment and geochemical evolution. Organic Geochemistry 18, 423 430. K6ster, J., Rospondek, M. J., Schouten, S., Kotarba, M., Zubrzycki, A., de Leeuw, J. W. and Sinninghe Damst6, J. S. (1998) Biomarker geochemistry of a foreland basin: the Oligocene Menilite Formation in the Flysch Carpathains of Southeast Poland. In Advances in Organic Geochemistry 1998, Eds B. Horsfield, M. Radke, R. G. Schaefer and H. Wilkes. Organic Geochemistry 29, 649-669. K6ster, J., Rospondek, M. J., Zubrzycki, A., Kotarba, M., de Leeuw, J. W. and Sinninghe Damst~, J. S. (1995) A molecular organic geochemical study of black shales associated with diatomites from the Oligocene Menilite Shales (Flysch Carpathians, SE Poland). In Organic' Geochemistry: Developments and Applications to Energy, Climate, Environment and Human History, Eds J. O. Grimalt and C. Dorronsoro, pp. 87-89. A.I.G.O.A., San Sebastian. Kotlarczyk, J. (1988) Zarys stratygrafii brzeznych jednostek tektonicznych orogenu karpackiego. In Karpaty Przemyskie--Przewodnik Zjazdowy. LIX Zjazdu Naukowy Polskiego Towarzystwa Geologicznego, Eds J. Kotlarczyk, K. Pekala and S. Gucik, pp. 31-63. Wydawnictwo Akademii G6rniczo-Hutniczej, Krak6w. Kotlarczyk, J. and Jerzmanska, A. (1988) Lito- i biostratygraphia warstw menilitowych na Krepaku; lupki z Niebylca z poziomem diatomit6w z Piatkowej. In Karpaty Przemyskie Przewodnik Zjazdowy. LIX Zjazdu Naukowy Polskiego Towarzystwa Geologicznego, Eds J. Kotlarczyk, K. Pekala and S. Gucik, pp. 107 113. Wydawnictwo Akademii G6rniczo-Hutniczej, Krak6w. Kotlarczyk, J. and Lesniak, T. (1990) Lower part of the Menilite Formation and related Futoma Diatomite Member in the Skole unit of the Polish Carpathians (in Polish with English summary), Wydawnictwo Akademii G6rniczo-Hutniczej, Krak6w, 74 pp. Kruge, M. A., Solecki, A. and Stankiewicz, B. A. (1991) Molecular organic geochemistry of black shales and related strata, Carpathian Mountains, Southeastern Poland. In Organic Geochemistry: Advances and Applications in the Natural Environment, Ed. D. Manning, pp. 59 63. Manchester University Press, Manchester. Kruge, M. A., Mastalerz, M., Solecki, A. and Stankiewicz, B. A. (1996) Organic geochemistry and petrology of oil source rocks, Carpathian Overthrust region, southeastern Poland--implications for petroleum generation. Organic" Geochemistry 24, 897-912. Ksiazkiewicz, M. (1960) Outline of the paleogeography in the Flysch Carpathians. Prace Polskiego Instytuto Geologicznego 30, 236-249. Lallier-Verg6s, E., Bertrand, P. and Desprairies, A. (1993) Organic matter composition and sulphate reduction intensity in Oman margin sediments. Marine Geology 112, 57 69. Langford, F. F. and Blanc-Valleron, M.-M. (1990) Interpreting Rock-Eval pyrolysis data using graphs of pyrolysable hydrocarbons vs total organic carbon. American Association of Petroleum Geologists Bulletin 74, 799-804.

558

J. K6ster et al.

Leszczynski, S. (1994) A process of basin euxinisation, Upper Eocene, Polish Carpathians. 15th Regional Meeting of the International Association of Sedimentologists. Ischia, Italy, April, 13-15, 1994, Abstract, p. 250. Leszczynski, S. and Malik, K. (1996) Skaly wapienne i wapniste we fliszu polskich Karpat zewnetrznych (Carbonates in flysch of the Polish Outer Carpathians). Przglad Geologiczny 44, 151-158. Leventhal, J. S. (1983) An interpretation of carbon and sulphur relationships in Black Sea sediments as indicators of environments of deposition. Geochimica Cosmochimica Acta 47, 133-137. Lewan, M. D. (1986) Stable carbon isotopes of amorphous kerogens from Phanerozoic sedimentary rocks. Geochimica Cosmochimica Acta 50, 1583-1591. Littke, R. (1993) Depostition, diagenesis and weathering of organic matter-rich sediments. Lecture Notes in Earth Sciences 47, 1-216. Mahel, M. (1978) Geotectonic positions of magmatites in the Carpathians, Balkan and Dinarides. In Zdpadn~ Karpaty Seria Geologla, Vol. 4, pp. 1-173. Geologick~, fistav Dion~za Stfira, Bratislava. Majorowicz, J. and Plewa, S. (1979) Review of heat flow measurements in Poland. In Terrestrial Heat Flow in Europe, ed. V. Cerm~k and L. Rybach, pp. 240-252. Springer, Berlin. Malata, T. (1997) Analysis of standard lithostratigraphic nomenclature and proposal of division for Skole unit in the Polish Flysch Carpathians. Geological Quarterly 40, 543 554. Ori, G. G. and Friend, P. F. (1984) Sedimentary basins formed and carried piggyback on active thrust sheets. Geology 12, 475-478. Peters, K. E. (1986) Guidelines of evaluating petroleum source rock using programmed pyrolysis. American Association ~["Petroleum Geologists Bulletin 70, 318-329. Ricou, L. E., Mercier de Lepinay, B. and Marcoux, J. (1986) Evolution of the Tethyan seaway and implications for the oceanic circulation around the EoceneOligocene boundary. In Terminal Eocene Events, Eds C. Pomerol and 1. Premoli-Silva. Developments in Sedimentology, Vol. 9, pp. 387-394. Elsevier, Amsterdam. Roca, E., Bessereau, G., Jawor, E., Kotarba, M. and Route, F. (1995) Pre-Neogene evolution of the Western Carpathians: Constraints from the Bochnia-Tatra Mountains section (Polish Western Carpathians). Tectonics 14, 855-873. Roure, F., Roca, E. and Sassi, W. (1993) The Neogene evolution of the Outer Carpathian flysch units (Poland, Ukraine and Romania): kinematics of a foreland/foldand-thrust belt system. SedimentalT Geology 86, 177 201.

Slaczka, A. (1996) Oil and gas in the Northern Carpathians. In Oil and Gas in Alpidic Thrustbelts and Basins of Central and Eastern Europe, Eds G. Wessely and W. Liebl. EAGE Special Publications 5, 187 195. Geological Society, London. Sofer, Z. (1980) Preparation of carbon dioxide for stable isotope analysis of petroleum. Analytical Chemistry 52, 1389-139l. Sofer, Z. (1984) Stable carbon isotope compositions of crude oils: Application of the source depositional environments and petroleum alteration. American Association of Petroleum Geologists Bulletin 68, 31-49. Stahl, W. J. (1978) Source rock/crude oil correlation by isotopic type curves. Geochimica Cosmochimica Acta 42, 1573-1577. ten Haven, H. L., Lafargue, E. and Kotarba, M. (1993) Oil/oil and oil/source rock correlations in the Carpathian Foredeep and overthrust, south-east Poland. Organic Geochemistry 20, 935-959. Tissot, B. P. and Welte, D. H. (1984) Petroleum Formation and Occurrence. Springer, Berlin, 699 pp. Unrug, R. (1979) Palinspastic reconstruction of the Carpathian Arc before the Neogene tectogenesis. Annales Societatis Geologorum Poloniae 49, 3 21. van Couvering, J. A., Aubry, M.-P., Berggren, W. A., Bujak, J. P., Naeser, C. W. and Wieser, T. (1981) The terminal Eocene event and the Polish connection. Palaeogeography, Palaeoclimatology, Palaeoecology 36, 321-362. Vet6, I. and Het~nyi, M. (1991) Fate of Organic carbon and reduced sulphur in dysoxic-anoxic Oligocene facies of the Central Paratethys (Carpathian Mountains and Hungary). In Modern and Ancient Continental Shelf Anoxia, ed. R. V. Tyson and T. H. Pearson. Geological Society Special Publication 58, 449 460. Geological Society, London. Vet6, 1., Het+nyi, M., Dembny, A. and Hertelendi, E. (1994) Hydrogen index as reflecting intensity of sulphidic diagenesis in non-bioturbated, shaly sediments. Organic Geochemistry 22, 299-310. Whiticar, M. J., Faber, E. and Schoell, M. (1986) Biogenic methane formation in marine and freshwater environments: CO_, reduction vs acetate fermentation-Isotope evidence. Geochimica Cosmoehimica Acta 50, 693-709. Wieser, T. (1985) The Teschenite Formation and other evidences of magmatic activity in the Polish Flysch Carpathians and their geotectonic and stratigraphic significance. In Fundamental Researches in the Western Part ~[' the Polish Carpathians. Guide Book to Excursion 1. CaiTatho-Balkan Geological Association Xll. Congress, Kracfw, Poland, 1985, Ed. T. Wieser, pp. 2336. Geological Institute, Krak6w.