depositional environment and hydrocarbon source potential of the lower miocene oil shale deposit in the aleksinac basin serbia abstract the most prolific oil shale deposit in serbia is located in the aleksinac basin and is assigned to the lower miocene depositional environments and hydrocarbon potential were assessed for the aleksinac oil shale and coal layers through bulk geochemical organic petrographical biomarker and carbon isotope data from core samples from a single well maturity parameters vitrinite reflectance tmax biomarker isomerisation ratios prove that the organic matter om is immature a lower lacustrine oil shale sequence is comprised of alternating sandstone and clay rich rocks and some thin coal beds indicating strong variations in depositional environment this stratum is covered with thick sandstone 50 m terminated by the main 4 m thick coal seam that was deposited in a low lying mire as evidenced by high total sulfur and mineral matrix contents the plant input was dominated by angiosperms a relative rise in water level led to the drowning of the swamp and to the deposition of a 60 m thick upper oil shale in a lacustrine environment the om of the oil shale is dominated by kerogen type i lamalginite biomarker data suggest a stratified water column that likely formed due to differences in salinity the stratified water column led to a strictly anoxic environment and photic zone euxinia in a mesosalinar hydrologically closed lake which enabled the accumulation of uncommonly high amounts of organic material average toc 18 0 wt with excellent preservation average hi 743 mg hc g toc

stable isotopic variations of clay minerals a key to the understanding of kupferschiefer type mineralization germany isotopic compositions of silicate minerals and carbonates of selected kupferschiefer samples from the hessian depression and from the lower rhine basin have been studied in detail in the area of the richelsdorf ore district stable isotope analyses of the cu mineralized sections in the kupferschiefer show that the metal enrichment processes are associated with significant changes in the oxygen and hydrogen isotope composition of the clay minerals the isotopic compositions of the 2 size fractions reflect a decrease of approximately 4 in 18o 18 4 to 13 7 and an increase of nearly 50 in d 74 to 25 with decreasing distance from the rote faule zone this isotopic zonation in the kupferschiefer shale is explained by fluid rock interaction with ascending oxidizing hypersaline solutions which transported high amounts of base metals from the lower permian red beds into the kupferschiefer horizon acting as a geochemical trap the estimated isotopic composition of the involved water 18o between 3 0 and 6 5 d between 10 and 3 supports the characterization of the ore bearing solutions as basinal brines internal oxygen isotope fractionation of illite from samples next to rote faule corresponds to a temperature of approximately 130 c which is suggested as the temperature of metal precipitation in the lower rhine basin the metal content does not exceed values commonly observed in black shales enhanced base metal pb zn mineralization is observed only in the bottom section of the kupferschiefer the results of the oxygen and hydrogen isotope analyses of the selected core samples provide no evidence for correlation between isotopic composition of the silicate minerals and the extent of lead and zinc sulphide precipitation futhermore they do not point towards isotopic exchange reactions between clay minerals within the kupferschiefer shale and fluids out of isotopic equilibrium with the investigated mineral phases however it is shown that the lack of detectable interaction between the rock and external fluids as reflected by these data in general coincides with the proposed concept that the base metals pb and zn as well as ba have been coprecipitated from carboniferous formation waters

microbe clay interactions as a mechanism for the preservation of organic matter and trace metal biosignatures in black shales abstract organic rich fine grained sedimentary rocks such as black shales are important geochemical archives providing information on the evolution of seawater composition and biological activity over the past 3 billion years while biological productivity and sedimentation rates greatly affect the organic matter content in these rocks mechanisms linking these two processes remain poorly resolved here we examine the interactions of clay minerals with the marine planktonic cyanobacterium synechococcus sp pcc 7002 we suggest that clays settling through the water column could influence carbon and trace metal burial in three ways 1 the interaction of reactive clay surfaces with the bacterial cells increases organic matter deposition via mass increase in a seawater growth medium by several orders of magnitude 2 reactive bacterial cells become completely encased within a clay shroud enhancing the preservation potential of this organic matter and 3 the trace metal content of the biomass buried along with metals sorbed to the clay particles contributes to the trace metal concentrations of the black shale precursor sediments significantly our findings imply that the chemical composition of ancient organic rich fine grained deposits are not only archives of ancient seawater composition and redox state but they also provide a record of the degree of biological activity in the water column through geological time

palaeoenvironment of the eocene eckfeld maar lake germany implications from geochemical analysis of the oil shale sequence abstract drill core samples from the depth interval between 19 4 and 32 0 m of the laminated central lake facies of the eocene eckfeld maar were investigated for biomarker and stable isotope composition bulk organic geochemical parameters c n hi and the molecular composition of the soluble organic matter indicate a dominance of particulate organic matter from land plants and microbially derived lipids in the lower part of the sedimentary succession an angiosperm dominated vegetation is indicated from the terpenoid biomarker composition abundant 4 methylsteroids in the 25 6 30 8 m section of the oil shale sequence reflect a contribution of algal derived biomass samples with high concentrations of methylsteroids are characterized by low amounts of triterpenoids related to the arborane skeleton and vice versa this pattern is interpreted as reflecting differences in autochthonous organic matter production vs microbial activity in the lowermost section 32 0 30 6 m a trend towards heavier 18 o and 13 c values indicates the evolution of permanently meromictic conditions in the lake and an increase in methanogenesis high 13 c values of siderites 10 throughout most of the sequence are consistent with permanently anoxic conditions at the sediment water interface the lighter 18 o values of siderites from turbidites relative to siderites from biogenic laminites are postulated to have been caused by temporary phases of increased precipitation followed by landslides and improved circulation within the lake depletion of the organic matter in 13 c average 13 c 29 4 in comparison with the fossil wood ranging from 23 1 to 26 6 is explained by the dominance of waxy lipid rich land plant material e g leaf waxes resins bark over wood supplied to the lake carbon cycling during anoxic decomposition of organic matter is assumed to further affect the 13 c values through the activity of anaerobic e g methanogenic bacteria resulting in a depletion of the biomass in 13 c the overall trend in the isotopic composition of organic carbon towards heavier values in the depth interval between 26 0 and 3 2 m is accompanied by decreasing c n ratios indicating an increase in aquatic organic matter production the geochemistry of the oil shale succession points towards a highly productive eutrophic ecosystem with intense microbial activity under meromictic conditions in the maar lake beside the high input of land plants to the biomass major contributions from bacteria and phytoplankton are indicated by the biomarker composition

the origin of the kupferschiefer type mineralization in the richelsdorf hills germany as deduced from stable isotope and organic geochemical studies abstract the kupferschiefer horizon in the richelsdorf section federal republic of germany acted as a geochemical trap by accumulating metals from ascending brines chemical composition of the extracted bitumens reflects a drastic change in the degree of oxidation of the organic matter towards rote faule this alteration pattern corresponds with regular changes in the isotopic composition of organic carbon and carbonate as well as with the base metal zonation around rote faule the enrichment of the organic material in 13c suggests the preferential release of isotopically light hydrogen equivalents through progressive degradation and oxidation of organic matter the opposite tendency towards lower 13c and 18o values of carbonate minerals provides evidence for isotopic reequilibration between carbonate and isotopically light oxidizing solutions the occurrence of isotopically heavy organic carbon together with low 13c and 18o values of carbonate suggests that 12c rich co2 generated due to oxidation of organic material may have been a source of carbonate the results reveal a post sedimentary formation of high grade mineralization and associated rote faule by ascending oxidizing brines they are in agreement with the results of mineralogical and geochemical studies which provided evidence for metal precipitation from basinal brines enriched in na and sulphate s the organic geochemical and isotopic data suggest that metal precipitation was caused by thermochemical sulphate reduction with organic matter acting as a reducing agent and proton donor

facies and rank of the permian kupferschiefer from the lower rhine basin and nw germany abstract the kupferschiefer of the lower rhine basin and of nw germany is a typical black shale containing c org values between 0 5 and 9 1 on average it contains 4 c org in coal petrographic terms the organic matter of the kupferschiefer is characterized by well preserved liptinite as sporinite especially derived from the pollen grains of conifers in the area of the lower rhine basin and as alginite towards the centre of the kupferschiefer sea the high content of bituminite in all of the samples shows that the main source of organic matter is derived from plancton and bacteria vitrinite and inertinite are rare the rank of the organic matter in the sediment varies between the lignite stage lower rhine basin and the bituminous coal stage nw germany geochemical investigations have shown that residual heat from the krefeld high was active until the lower zechstein this has caused a change in the chemical composition of the organic matter but did not express itself in the optical parameters inhomogeneities of the organic matter in low rank and bituminization in higher rank materials influence the vitrinite reflectance fluorescence measurements are more sensitive in sapropelic sediments and oil shales than vitrinite reflectance it is evident that the red green ration is more reliable in view of diagenesis studies than the lambda max of the fluorescence spectra geochemical parameters are partly much more sensitive towards thermal stress as compared to vitrinite reflectance e g metalloporphyrin concentrations decrease with increasing temperatures the parameter covers a temperature range from ca 40 c to 80 c the weighted average mass of the vanadyl cycloalkano porphyrins is suitable to characterize the influence of temperature on the kupferschiefer between ca 40 c and 150 c summing up the kupferschiefer of the lower rhine basin in nw germany is a sidiment very well suited for parallel petrographic and organic geochemical research the results of this might be also of interest in the field of oil prospecting

geophysical evidence for karst formation associated with offshore groundwater transport an example from north carolina 1 marine geophysical data from long bay north carolina involving a novel combination of electromagnetic and high resolution chirp seismics show evidence of submarine karst formation associated with what has been inferred to be a site of high flux submarine groundwater discharge sgd a substantial distance offshore recently observed temperature and chemical signals from wells in this area provide the basis for the interpretation of the high flux sgd here and they also suggest a terrestrial source for the groundwater and thus a potentially important route for nutrient transport to the oceans our data indicate that karstification is localized to the high flux zone and we suggest that mixing of the chemically distinct but saline groundwater with seawater has resulted in the karstification as karstification increases permeability and flux a positive feedback would tend to progressively enhance submarine groundwater discharge our data reveal a significant local anomaly in apparent porosity a dense block that may have initiated the local focusing of groundwater flow conditions favorable to the formation of similar locally punctuated sites of high flux sgd are likely to exist along the mid to inner shelf of the southeastern united states where carbonate aquifers are prevalent

palaeoceanography of the early zechstein sea during kupferschiefer deposition in the lower rhine basin germany a reappraisal from stable isotope and organic geochemical investigations abstract in the study area of the lower rhine basin the permian kupferschiefer was deposited in a shallow water environment water exchange from this marginal basin with the zechstein sea was restricted by palaeohighs the burial depth of the shale did not exceed 1000 m during the depositional history of most parts of the basin maturation of the organic matter was governed only by the geothermal gradient not exceeding 68 c km during the late carboniferous due to minor thermal alteration of organic matter diagenetic effects on the biomarker composition and the light stable isotope ratios c h o n of organic matter and carbonates are of minor importance in the present study isotopic and organic geochemical data are interpreted with respect to palaeoceanographic aspects the data provide information about salinity variations the nature of organisms living in the water column and the importance of bacterial activity in the sediment during deposition from the degree of methylation of 2 methyl 2 trimethyl tridecylchromans mttc an euhaline to mesohaline 30 40 sea water salinity during kupferschiefer sedimentation can be inferred the high abundance of biomarkers derived from green purple sulphur bacteria suggests h2s saturation of the bottom waters and maximum water depths below 100 m in the basin because these organisms live near the boundary between the photic zone and the anoxic euxinic bottom water at a depth of 10 30 m primary production in the upper water column was dominated by photosynthetic cyanobacteria or green algae in the sediment sulphate reduction occurred due to the availability of abundant sulphate and organic detritus from the overlying water column furthermore methanogenesis was active mostly during early kupferschiefer deposition this is reflected by the light carbon isotopic composition of organic matter originating from recycling of co2 generated by methane oxidizing bacteria in the water column saccate pollen are the only morphologically preserved organic matter in the sediment

the role of the kupferschiefer in the formation of hydrothermal base metal mineralization in the spessart ore district germany insight from detailed sulfur isotope studies the spessart district sw germany located at the southwestern margin of the permian kupferschiefer basin in central europe hosts abundant stratabound and structurally controlled base metal mineralization the mineralization styles identified are 1 stratabound cu pb zn ag ores in zechstein sedimentary rocks 2 structurally controlled cu as ag ores in zechstein sedimentary rocks 3 crosscutting co ni bi as and cu fe as veins 4 stratabound metasomatic fe mn carbonate ores in zechstein dolomite 5 barren barite veins and 6 fe mn as veins in permian rhyolites building on previous work that involved mineralogical textural and chemical characterization of the major mineralization types we have performed a comprehensive sulfur isotope study that applied both conventional and novel laser ablation multi collector inductively coupled plasma mass spectrometry techniques the 34s values of sulfide minerals from the different ore types are consistently negative and highly variable in the range between 44 5 and 3 9 whereas the 34s values of barite are all positive in the range between 4 7 and 18 9 remarkably stratabound and structurally controlled mineralization in zechstein sedimentary rocks has the least negative 34s values whereas vein type deposits have consistently more negative 34s values the observed pattern of sulfide 34s values can be best interpreted in terms of fluid mixing at the basement cover interface hydrothermal fluids originating from the crystalline basement migrated upward along subvertical fault zones and were periodically injected into groundwaters that were flowing in the post variscan sedimentary cover these groundwaters had interacted with the zechstein sedimentary rocks resulting in fluids characterized by elevated concentrations of reduced sulfur with negative 34s values and alkaline ph repeated mixing between both chemically contrasting fluids caused rapid and efficient precipitation of sulfide ore minerals in hydrothermal veins with highly variable but distinctly negative 34s values

problematic urn shaped fossils from a paleoproterozoic 2 2ga paleosol in south africa abstract small 0 3 1 8 mm long locally abundant urn shaped fossils within surface horizons of a paleosol in the 2 2 ga hekpoort formation near waterval onder south africa are here described and named diskagma buttonii retallack gen et sp nov the fossils are from fresh rock of a deep highway cutting and have been metamorphosed to upper greenschist facies like their matrix despite metamorphic alteration total organic carbon of the samples was 0 04 and its isotopic composition 13 c was 25 6 0 08 two standard deviations versus vienna pee dee belemnite standard organic outlines of the fossils are also accentuated by recystallized berthierine and opaque oxides the fossils are locally clumped within surface swales of a vertisol paleosol identified from characteristic penecontemporaneous deformation clastic dikes between swales of mukkara structure and from pronounced geochemical differentiation phosphorus and copper strain corrected mass depletion characteristic of an oxidized biologically active soil this paleosol s chemical composition is evidence of temperate humid climate mean annual temperature 11 3 4 4 c and mean annual precipitation 1489 182 mm associated paleosols indicate atmospheric co 2 of 6640 12 880 4293 ppm 0 6 and 0 9 5 atmospheric o 2 the best preserved examples of diskagma are shaped like an urn with a flared rim and closed below the flare observation of hundreds of specimens in thin section reveals substantial variation in growth elongation and decay shredding and deflation they had a hollow ellipsoidal interior that is unusually devoid of opaque debris unlike the matrix diskagma is superficially comparable with lichens such as cladonia ascomycota and geosiphon glomeromycota definitive reproductive structures remain unknown they predate the oldest other likely fossil eukaryotes 1 9 ga and fungi 1 5 ga and current molecular clock estimates for eukaryotes 1 6 ga and fungi 1 1 ga lichenized actinobacteria are plausible prokaryotic alternatives permitted by molecular clocks although biological affinities of diskagma are uncertain these fossils reveal the general appearance of paleoproterozoic life on land

unconventional reservoir potential of the upper permian zechstein group a slope to basin sequence stratigraphic and sedimentological evaluation of carbonates and organic rich mudrocks northern germany the late permian zechstein group in northeastern germany is characterized by shelf and slope carbonates that rimmed a basin extending from eastern england through the netherlands and germany to poland conventional reservoirs are found in grainstones rimming islands created by pre existing paleohighs and platform rimming shoals that compose steep margins in the north and ramp deposits in the southern part the slope and basin deposits are characterized by debris flows and organic rich mudstones lagoonal and basinal evaporites formed the seal for these carbonate and underlying sandstone reservoirs the objective of this investigation is to evaluate potential unconventional reservoirs in organic rich fine grained and or tight mudrocks in slope and basin as well as platform carbonates occurring in this stratigraphic interval therefore a comprehensive study was conducted that included sedimentology sequence stratigraphy petrography and geochemistry sequence stratigraphic correlations from shelf to basin are crucial in establishing a framework that allows correlation of potential productive facies in fine grained organic rich basinal siliceous and calcareous mudstones or interfingering tight carbonates and siltstones ranging from the lagoon to slope to basin which might be candidates for forming an unconventional reservoir most organic rich shales worldwide are associated with eustatic transgressions the basal zechstein cycles z1 and z2 contain organic rich siliceous and calcareous mudstones and carbonates that form major transgressive deposits in the basin maturities range from over mature gas in the basin to oil generation on the slope with variable toc contents this sequence stratigraphic and sedimentologic evaluation of the transgressive facies in the z1 and z2 assesses the potential for shale gas oil and hybrid unconventional plays potential unconventional reservoirs might be explored in laminated organic rich mudstones within the oil window along the northern and southern slopes of the basin although the zechstein z1 and z2 cycles might have limited shale gas potential because of low thickness and deep burial depth to be economic at this point unconventional reservoir opportunities that include hybrid and shale oil potential are possible in the study area

biotic and abiotic processes in the formation and diagenesis of permian dolomitic stromatolites zechstein group ne england abstract the crinkly bed of the upper permian zechstein group succession roker formation hauptdolomit z2c in northeast england is a distinctive 1 4 meter thick unit that has been interpreted as a stromatolite of microbial origin or alternatively as the result of purely abiotic precipitation close examination of this stratigraphically significant unit shows that it is the result of both physical and microbial processes and was deposited in hypersaline shallow water immediately following lowstand evaporite deposition within the zechstein basin the internal structure of the crinkly bed consists of fine millimeter scale laminae of alternating clotted peloidal or aphanitic micritic layers and granular laminae composed of silt size peloids with rare hollow spheroids the lamination is extremely regular in thickness and laterally persistent for up to 4 meters a microbial community composed of coccoid and filamentous microorganisms inferred from fossil evidence colonized the original sediment surface it is suggested that this biofilm was responsible for the precipitation of both the micrite laminae and most of the peloids of the granular laminae the peloids are consequently interpreted as autochthonous this interpretation of a microbial origin is consistent with the microstructure and geochemical signatures of the micritic dolomite which constitutes both the continuous micritic laminae and the peloids themselves primary dolomite precipitation is hypothesized to have taken place from marine to slightly hypersaline waters mediated by bacterial metabolism similar to the process that operates in modern intertidal microbial mats the crinkly bed shows macro structures that vary along a continuum from symmetrical to asymmetrical centimeter scale ripple like structures some showing interference patterns through to domical and conical structures more typical of stromatolites the more ripple like structures have a lamination of microbial origin identical to that within the domal conical stromatolites there is no internal cross lamination their origin is equivocal they could be the result of physical current or wave induced deformation of a surficial biofilm or their form could be inherited from true mechanically deposited ripples not observed that provided a template for biofilm growth changes in the nature and strength of the wave and or current regime and possibly in the community structure of the microbial mat produced this array of microbially induced macrostructures miss the latter plus the absence of desiccation features indicative of intertidal to supratidal deposition suggest subtidal sedimentation at a depth of several meters intergranular gypsum cement precipitated during early diagenesis and ferroan sparry dolomite precipitated during burial tertiary uplift and the consequent exposure to meteoric waters resulted in the precipitation of calcite cements that replaced gypsum and pre existing dolomite probably via the biological mediation of heterotrophic bacteria the interpretation of this distinctive stratigraphic unit illustrates the difficulty in distinguishing between biotic and abiotic processes in the sedimentary record

the origin of hydrocarbon source rocks in the austrian molasse basin eocene oligocene transition organic rich rocks schoneck formation from five wells representing a section across the northern paleo slope of the austrian molasse basin were studied using a multi method approach including petrography x ray diffraction organic and inorganic geochemistry and c and n isotopes of the organic material organic matter accumulation commenced during the latest eocene and was dependent on variations of currents salinity organic productivity and nutrient supply initial marl deposition and phosphorite formation under dysoxic conditions was followed by organic rich mud deposition associated with benthic and photic zone anoxia this paleoceanographic situation resembles the first isolation of the western central paratethys deposition of organic rich rocks terminated during lower oligocene time when changing current patterns and decreasing salinity caused a breakdown of water column stratification even though the schoneck formation is an excellent source rock major differences exist in the petroleum potential of the schoneck formation deposited in upper and lower basin slope settings the schoneck formation from the upper slope is characterised by toc contents up to 12 and hi values between 500 and 600 mghc gtoc in the lower slope settings toc values are generally below 2

geochemical characteristics across the oxic anoxic interface rote faule front within the kupferschiefer of the lubin sieroszowice mining district sw poland abstract samples of profiles from lower zechstein in the lubin sieroszowice mining district sw poland were collected within and at different distance to the oxidized facies rote faule developed within the zechstein strata around the zary pericline the samples include kupferschiefer underlying weissliegendes sandstone and overlying zechstein limestone from rote faule zones adjacent cu mineralized strata and drill cores from the pb zn mineralized zone more distant to the rote faule front the kupferschiefer samples show differences in ore paragenesis and composition of organic matter which are accompanied by variations in base metal and trace element contents and isotope ratios of organic carbon and carbonates the results from rock eval analyses provide evidence for an oxidative alteration of organic matter in kupferschiefer samples within and adjacent to the rote faule zones related to base metal mineralization the extent of this alteration is reflected by differences in the temperature of maximum pyrolysis yield t max hydrogen and oxygen indices hi oi in contrast to kupferschiefer from pb zn mineralized areas organic matter is characterized by lower hydrogen equivalents and by higher t max values the changes in the isotopic composition of organic carbon and carbonates reflect the alteration of organic matter kerogen within or close to rote faule zones is enriched in 13 c caused by the preferential release of isotopically light organic compounds through progressive degradation of organic matter the opposite tendency towards lower 13 c values of calcite provides evidence for organic matter remineralization isotopic exchange reactions of carbonate with the isotopically distinct oxidizing brines at temperatures between 100 and 120 c caused decreasing 18 o values of calcite the regional zonation in the kupferschiefer with respect to sulfide paragenesis and base metal composition in the mines is explained by metal precipitation from oxidizing brines through decreasing eh conditions during the infiltration of the brines into the reduced kupferschiefer relationships between selected trace elements organic carbon and sulfur contents and hi values are consistent with that model of ore formation

combined isotopic and biomarker investigations of temperature and facies dependent variations in the kupferschiefer of the lower rhine basin northwestern germany abstract organic material in selected kupferschiefer samples from the lower rhine basin of nw germany has been studied using gas chromatography gc coupled gas chromatography mass spectrometry gc ms as well as c and h isotopic analyses of the organic matter o and c isotope compositions of carbonates have also been investigated the study area is located at the southwest shore of the ancient zechstein ocean the permian kupferschiefer was deposited here under anoxic lagoonal conditions five closely sampled profiles were analysed covering a total depth range of 350 760 m in order to detect temperature sensitive variations and compositional changes during kupferschiefer deposition variations in isotopic and molecular compositions of organic material as well as in calcite 13c within the kupferschiefer section in proximity of the basic intrusion that forms the krefeld high are the result of post sedimentary thermal degradation of organic matter variations in the 18o values of carbonates are governed primarily by the mineralogical composition cao mgo ratios outside this area the isotopic data point toward a slightly increasing salinity of the seawater during kupferschiefer sedimentation an input of terrigenous organic matter is indicated by the occurrence of the ring a degraded pentacyclic triterpenoid des a arborene the compound is thought to be generated from the related pentacyclic precursor by anaerobic bacteria the significant decrease of the compound towards the top of the kupferschiefer correlates with decreasing anoxic conditions during kupferschiefer sedimentation

temperature effects on kerogen and on molecular and isotopic composition of organic matter in pierre shale near an igneous dike abstract a suite of siltstone samples from the upper cretaceous pierre shale from the contact zone of a 130 cm thick igneous dike near wolcott colorado u s a was taken from the contact to 170 cm from the dike to study the effects of temperature on the organic matter the sampled bedding interval was about 10 cm thick so variation in lithology and type of organic matter is minimal vitrinite reflectance values r 0 increase from 0 4 far from the dike to 3 3 near the dike contact geochemical measurements show systematic thermal effects analogous to those often observed for catagenesis and metagenesis in the depth range of 1 4 km within a sedimentary basin the h c ratio of kerogen and the hydrogen index rock eval decrease most rapidly in the 0 6 1 7 r 0 range in which the transformation ratio rock eval increases from 0 1 to 0 3 based on extraction of c 15 compounds the main increase of hydrocarbons and total extractable organic matter occurs between 0 6 and 1 0 reflectance the saturated aromatic hydrocarbon ratio increases almost twofold in this range of maturity however the pristane phytane ratio is essentially constant through the hydrocarbon generation zone but decreases slightly at high levels of thermal alteration r 0 1 2 the 13 c values for aromatic and saturated hydrocarbons are about 27 and 29 respectively and are constant to about 1 0 r 0 then both become heavier by about 2 at higher r 0 values

microscale biopitting by the endolithic lichen verrucaria baldensis and its proposed role in mesoscale solution basin development on limestone data are reported demonstrating the potential role of microscale morphologies induced by endolithic lichen communities specifically verrucaria baldensis in the initiation and development of mesoscale solution basin formation on limestone in the burren county clare a biophysical model is proposed outlining the different microscale stages leading to solution basin initiation with a progression from initial lichen colonization and growth associated perithecial biopitting followed by biopit coalescence to form biotroughs their subsequent enlargement and eventual incipient solution basin formation this model provides one explanation for solution basin development as this end state may also be achieved through simple solutional means without biological input the complexity of interactions at the lichen rock interface are identified with emphasis on the spatial and temporal variability of these underlining the point that as with macrotopographies at the landscape scale rock surface microtopographies also reflect historical weathering legacies copyright 2011 john wiley sons ltd

the precambrian nonesuch formation of the north american mid continent rift sedimentology and organic geochemical aspects of lacustrine deposition abstract the precambrian keweenawan trough in the lake superior region of north america is part of a failed intractonic rift that is filled with a thick sequence of volcanic and sedimentary rocks one unit in this sequence the none such formation is composed of black to green siltstones and shales and is conformable with the underlying alluvial copper harbor conglomerate and the overlying fluvial freda sandstone the formation is exposed as a lens in northern michigan and wisconsin and attains a maximum thickness of 200 m based on the integration of outcrop and core data nine facies have been recognized in the formation each has been assigned to one of three genetic facies assemblages a marginal lacustrine assemblage characterized by interbedded lithic sandstones siltstones mudstones and sandstone shale couplets is interpreted as a record of deposition on a sandflat mudflat complex a lacustrine assemblage is characterized by massive to well laminated dark shaly siltstones carbonate laminites shales siltstones and mudstones these sediments were probably deposited in a progressively shallowing perennial lake bottom conditions were anoxic and became increasingly more oxic as lake regression progressed a gradual transition from a lacustrine environment to a fluvial environment is represented by the red to brown massive horizontally laminated and rippled fine sandstones siltstones and mudstones of the fluvial lacustrine assemblage interactions among rates of subsidence rates of sedimentation fluctuations in lake level possible changes in climate and differences in tectonic setting controlled sedimentation in the nonesuch lake and resulted in variable vertical facies sequences total organic carbon toc analyses show a strong correlation between organic richness and the shale facies lacustrine assemblage and mudstone facies marginal lacustrine assemblage detailed petrographic analysis using incident white light and reflected blue light fluorescence revealed two prevalent organic petrographies which could be distinguished using combined pyrolysis gas chromatography mass spectrometry py gc ms and to a limited extent by stable carbon isotope mass spectrometry the geographic and stratigraphic distribution of rocks containing the two organic petrographies suggests that differential preservation e g microbial degradation accounts for the difference rather than maturity or variable source input

evolution of lacustrine systems along the miocene mur murz fault system eastern alps austria and implications on source rocks in pull apart basins tectonically controlled lakes developed during miocene lateral extrusion of the eastern alps mineralogy and the inorganic and organic geochemistry of rocks from three boreholes were investigated to reconstruct the evolution of lake ingering and lake groisenbach and to study the distribution of source rocks in pull apart basins gas prone coal and oil prone sapropelic shale accumulated during the initial shallow stages of lake ingering thereafter the lake deepened rapidly 125 m thick prodelta shale containing a type ii kerogen was deposited in the brackish several hundred meter deep hydrologically closed lake afterwards decreasing subsidence allowed the filling of the lake by prograding deltas during the advance of the deltaic systems the lake became shallower hydrologically open and the brackish influence terminated source rock quality decreased significantly during the filling stage of the lake a consequence of dilution of autochthonous organic matter and of enhanced input of land plants despite its considerable dimensions formation and filling of lake ingering lasted only two million years lake groisenbach was considerably smaller and more susceptible to high frequency changes in lake chemistry although the water body was temporarily oligosaline brackish conditions did not occur high sulphur contents were due to anoxic events and the inflow of ca rich waters abundant dissolved silica favoured diatoms blooms

effect of a dolerite intrusion on triterpane stereochemistry and kerogen in rundle oil shale australia abstract stereochemical changes of triterpanes present in extracts from an immature oil shale sequence intruded by a 3 m dolerite sill have been studied by gas chromatography mass spectrometry gc ms the steric configuration of the hopanes was observed to change from one dominated by the thermally less stable 17 h 21 h configuration at some distance from the intrusion to one dominated by the thermally more stable 17 h 21 h and 17 h 21 h configurating in the immediate vicinity of the intrusion in addition severe alteration of the kerogen appeared to have taken place as a result of the contact metamorphism and high concentrations of extractable organic matter were observed below the intrusion characterization of the kerogens by curie point pyrolysis has enabled the effects of the intrusion on the shales to be monitored

polymetallic mineralization at the browns deposit rum jungle mineral field northern territory australia the rum jungle mineral field northern territory australia forms part of the paleoproterozoic pine creek orogen the geology of the area comprises two archean granitic basement domes overlain by a paleoproterozoic sequence of metasedimentary and subordinate metavolcanic rocks the rocks have been deformed and metamorphosed to greenschist facies during the 1880 ma barramundi orogeny but the original stratigraphic succession has been preserved the browns deposit browns and its extension browns east hosted within black carbonaceous pelites of the paleoproterozoic whites formation is the largest base metal deposit found to date in the pine creek orogen present resource estimates are 39 million metric tons mt at 0 44 percent cu 3 61 percent pb 0 11 percent co and 0 09 percent ni browns and 31 mt at 1 29 percent cu 1 28 percent pb 0 13 percent co and 0 13 percent ni browns east major sulfide minerals in the ore zone are galena sphalerite chalcopyrite pyrite and the main carrier of ni and co siegenite ni co 3 s 4 digenite group minerals and bornite ca bearing plumbogummite pbal 3 po 4 2 oh 5 h 2 o arsenopyrite and gersdorffite are present in minor quantities ore minerals occur as fine grained wisps parallel to the main bedding parallel foliation and as coarse grained mono and polyminerallic aggregates that crosscut the foliation total noncarbonate carbon contents of unaltered rocks range from 1 07 to 7 51 wt percent total sulfur contents range from 2 13 to 6 14 wt percent petrographic studies and raman spectroscopy identify three varieties of carbonaceous matter primary syngenetic premetamorphic epigenetic grain coating and postmetamorphic epigenetic uraniferous migrated altered rocks are rarely encountered values of 34 s for sulfides range from 5 to 15 per mil and are interpreted to reflect a combination of inorganic thermochemical reduction of seawater and bacterial activity no specific sulfur isotope patterns for individual minerals can be established indicating nonequilibrium conditions homogeneous lead isotope signatures of galena 206 pb 204 pb 16 20 16 22 207 pb 206 pb 15 48 15 51 208 pb 207 pb 35 86 35 92 suggest that all pb was derived from a single crustal source and paragenetically late crosscutting galena appears to have been remobilized from bedding parallel galena despite the occurrence of uranium in similar rocks nearby uranium is quantitatively insignificant in the browns deposit and is not genetically related to base metal mineralization instead it is linked to brittle deformation in the waning stages of orogenesis the browns deposit differs from other well known sediment hosted stratiform ore deposits both the zambian copperbelt and the polish kupferschiefer deposits are copper dominant and hosted in sedimentary sequences with significant psammitic components the pb zn ag deposits of the proterozoic australian zinc province also have significant carbonate in their host rocks e g carbonaceous dolomitic and siltstone at mcarthur river and lack economically interesting cu co and ni the nearby woodcutters pb zn ag deposit in rocks of similar age also differs in structural setting veins dominant metals and pb isotopes from the browns deposit

identification of aryl isoprenoids in source rocks and crude oils biological markers for the green sulphur bacteria abstract a series of c13 to c31 aryl isoprenoids 1 alkyl 2 3 6 trimethylbenzenes have been identified in reef hosted oils and their source rocks from the middle and upper silurian of the michigan basin and middle devonian of the alberta basin canada their structure has been confirmed by unambiguous synthesis of the c14 member of the series their structure and isotopic composition indicate that they are derived from isorenieratene from the chlorobiaceae family of sulphur bacteria these results are consistent with geological and geochemical studies that show that the source rocks were deposited under metahaline to hypersaline sulphate and sulphide rich water columns the distribution of other biomarkers in these oils and source rocks indicates that a diverse biota contributed organic matter to the source environment in conjunction with the aryl isoprenoids they show that there is a remarkable similarity in composition between the two sets of oils and source rocks despite their great temporal and geographic separation this reflects the similarity of their environments and emphasizes the importance of sedimentary facies in controlling the composition of organic matter in source rocks and their derived oils

a paleoweathering profile from griqualand west south africa evidence for a dramatic rise in atmospheric oxygen between 2 2 and 1 9 bybp a core drilled near wolhaarkop in griqualand west south africa intersected highly oxidized kuruman iron formation below red beds of the gamagara formation the lateral equivalents of the kuruman iron formation in this drill hole consist largely of siderite ankerite magnetite greenalite and quartz the oxidation of the kuruman iron formation in wol 2 occurred almost certainly during weathering prior to the deposition of the gamagara formation the date of this weathering episode is bracketed between about 2 2 and 1 9 bybp by the age of the ongeluk lavas in the transvaal sequence below the unconformity and by the age of the hartley lavas in the olifantshoek group above the unconformity the ratio of iron to sio2 in the several facies of the weathered kuruman iron formation in wol 2 is nearly the same as that in their unweathered equivalents since sio2 loss during weathering was almost certainly minor the similarity of the fe sio2 ratio in the weathered and unweathered bif indicates that nearly all the feo in the kuruman iron formation was oxidized and retained as feo3 during weathering such a high degree of iron retention is best explained by an o2 content of the atmosphere or 0 03 atm at the time of weathering such an o2 pressure is very much greater than that suggested by the composition of paleosols developed on basalt or 2 2 bybp but is consistent with the highly oxidized nature of the 1 85 by flin flon paleosol the new data suggest that po2 rose dramatically from about 1 percent pal present atmospheric level to or 15 percent pal between 2 2 and 1 9 bybp

the marl slate a model for the precipitation of calcite dolomite and sulphides in a newly formed anoxic sea detailed studies of a new complete marl slate core in south yorkshire have provided information on isotopic 13c 18o 34s and geochemical variations trace elements and c s ratio which enable the formulation of a model for carbonate and sulphide precipitation in the late permian zechstein sea calcite and dolomite are intimately associated the fine lamination organic character and absence of benthos in the sediments are indicative of anoxic conditions lithologically the core can be divided into a lower predominantly sapropelic marl slate 2 m and an upper transition zone 0 65 m of alternating sapropel and calcite rich and dolomite rich carbonates c s ratios are 2 22 for the marl slate and 1 72 for the transition zone respectively both characteristic of anoxic environments 18o in the carbonates shows a large and systematic variation closely mirrored by variations in calcite dolomite ratio the results suggest a fractionation factor equivalent to a depletion of 3 8 for 18o and 1 5 for 13c in calcite the 34s values of pyrite are isotopically light mean value 32 7 suggesting a fractionation factor for the marl slate of almost 44 typical of anoxic basins the results are related to stratification in the early zechstein sea calcite was precipitated in oxic upper layers above the halocline below the oxic anoxic boundary framboidal pyrite was precipitated resulting in lower sulphate concentration and elevated mg ca ratio due to calcite precipitation as a result of this dolomite formation occurred below the oxic anoxic interface within the anoxic water column and in bottom sediments variations in calcite dolomite ratios and isotopic variations are thus explained by fluctuations in the relative level of the oxic anoxic boundary in the zechstein sea

molecular evidence for basin scale photic zone euxinia in the permian zechstein sea abstract previous studies of maleimides 1 h pyrrole 2 5 diones oxidative degradation products of chlorophylls and bacteriochlorophylls and aromatic compounds derived from certain carotenoids i e isorenieratene indicate that photic zone euxinia pze occurred at least intermittently during deposition of the german kupferschiefer late permian however that work was restricted to a stratigraphic profile through the kupferschiefer of the lower rhine basin a shallow lagoon setting and it was not established if photic zone euxinia prevailed in the larger and deeper basins of the permian zechstein sea here we present maleimide and porphyrin distributions in sediments from the northern and southern permian basins in samples from both basins methyl iso butyl me i bu maleimide was recovered from the free extractable fraction and upon oxidation of vanadyl and nickel alkyl porphyrins on structural grounds me i bu maleimide derives ultimately from bacteriochlorophyll bchl c d or e and is thus indicative of the presence of green sulfur bacteria in the ancient zechstein sea consistent with this c 34 and c 35 porphyrins apparently derived from bacteriochlorophyll d were also identified in the northern basin samples because green sulfur bacteria require both light and free h 2 s these results indicate that photic zone euxinia occurred at least periodically during the early history of the zechstein sea

use of biological marker distributions to study thermal history of the permian kupferschiefer of the lower rhine basin in the central european zechstein basin the permian kupferschiefer has been deposited under marine anoxic conditions from a lagoon at the southwest border of the zechstein sea today part of the lower rhine basin 30 core samples have been studied by means of organic geochemical methods within the area investigated the depth of the kupferschiefer horizon increases from about 350 m in the south to about 1000 m in the north furthermore the kupferschiefer has been thermally affected in the western part by the intrusive body of the so called krefeld high this geological situation opens the possibility to investigate differences of short term and long term temperature effects on the biological marker distribution within a sediment layer of a largely uniform facies type depth related changes in the hopane sterane and diasterene diasterane distributions are compared to those changes induced by the krefeld high the composition of aromatic steroid hydrocarbons is used to discuss time temperature effects it is shown that depth related values of maturation parameters can only be interpreted by taking into account post depositional tectonic events samples from tectonic horst structures show higher maturation values than one would expect from the present day depth

the sources and deposition of organic matter in the late quaternary pigmy basin gulf of mexico abstract the concentration and carbon isotopic composition 13c of sedimentary organic carbon corg n c ratios and terrigenous and marine 13corg endmembers form a basis from which to address problems of late quaternary glacial interglacial climatic variability in a 208 7 m hydraulic piston core dsdp 619 from the pigmy basin in the northern gulf of mexico while interpretations of sedimentary 13corg time series records are often not unique paired analyses of 13corg and n c are consistent with the hypothesis that the corg in the pigmy basin is a climatically determined mixture of c3 photosynthetic terrigenous and marine organic matter confirming the earlier 13corg model of sackett 1964 a high resolution 1 4 2 9 ka sample 13corg record shows that sedimentary organic carbon in interglacial oxygen isotope sub stages 1 and 5a b are enriched in 13c average 1 values are 24 2 1 2 o and 22 9 0 7 o relative to pdb respectively while glacial isotope stage values 2 are relatively depleted 25 6 0 5 concentrations of terrigenous and marine sedimentary organic carbon are calculated for the first time using 13corg and corg measurements and empirically determined terrigenous and marine 13corg endmembers the net accumulation rate of terrigenous organic carbon is 4 3 2 6 times higher in isotope stages 2 4 than in sub stages 1 and 5a b recording higher erosion rates of terrigenous organic material in glacial times the concentration and net accumulation rates of marine and terrigenous corg suggest that the nutrient bearing plume of the mississippi river may have advanced and retreated across the pigmy basin as sea level fell and rose in response to glacial interglacial sea level change

stable carbon isotopes of amorphous kerogens from phanerozoic sedimentary rocks amorphous kerogens from phanerozoic sedimentary rocks may be divided into two groups on the basis of their 13c values h amorphous kerogens have isotopic values in the range of 24 to 20 per mil and l amorphous kerogens have isotopic values in the range of 35 to 26 per mil the occurrence of amorphous kerogens in the intermediate isotopic range from one rock unit in the data set suggests a weak continuum may exist between these two groups phytoplankton and to a lesser extent zooplankton and bacteria are considered to be the precursors for both kerogen types a plausible explanation for this dichotomy may be found in the source of co2 utilized by phytoplankton which is considered to be controlled by environmental factors h amorphous kerogens are expected to occur in silled basins that are overlain by expansive well circulated deep 500 m water where the prevailing source of carbon in the photic zone is atmospheric derived co2 conversely l amorphous kerogens are expected to occur in restricted basins that are overlain by stratified shallow 200 m water where the prevailing source of carbon in the photic zone may be organic derived co2

paleoenvironmental implications from biomarker and stable isotope investigations on the pliocene velenje lignite seam slovenia a pliocene lignite seam up to 160 m thick occurs in the velenje basin slovenia the seam originated in a topogenous mire and evolved within a non marine transgressive setting differences in soluble organic matter yield and hydrocarbon content of borehole samples from the lignite are related to differences in the composition of free lipids of microbial origin and or hydrocarbons derived from the biogeochemical degradation of plant tissue variations of the redox conditions within the mire are reflected by pristane phytane ratios the abundance of terpenoid biomarkers indicates the predominance of gymnosperms over angiosperms which is consistent with palynomorphic spectra dominated by pollen of the sequoia taxodium metasequoia plant community rather than by angiosperms evidence is also provided that the content of land plant derived biomarkers and the preservation of plant tissue is controlled by the input of resin rich decay resistant conifers sections of the seam characterized by a high degree of gelification of humotelinite gelification index show high contents of hop 17 21 ene but low hopane concentrations the results suggest that the gelification of plant tissue may be governed by the activity of anaerobic rather than aerobic bacteria despite the minor variation in the proportions of gymnosperms versus angiosperms in the peat forming vegetation a general influence of the floral assemblage on carbon isotopic composition of the coals 13c 25 3 to 27 0 is proposed carbon cycling during biogeochemical decomposition of plant tissue by bacteria is assumed to affect the 13c value of the lignite petrographic and geochemical data of gelified and ungelified fossil wood provide evidence that gelification may be governed by microorganisms e g anaerobic bacteria different from those responsible for decreasing cellulose contents during early diagenetic aerobic degradation of wood based on the molecular composition of terpenoid biomarkers the wood fragments are identified as derived from gymnosperms the relative proportions of saturated versus aromatic hydrocarbon fractions of fossil gymnosperms display a general tendency towards lower values in gelified wood remains this indicates that bacteria involved in gelification of plant tissue may also be involved in aromatisation of diterpenoid hydrocarbons the chemotaxonomical classification of the macrofossils as gymnosperms is corroborated by the mean carbon isotopic compositions of the macrofossils 13c 24 5 and the extracted cellulose 13c 22 0 the higher isotopic difference of about 2 5 between cellulose and fossil wood compared to that found in modern trees can most probably be explained by the smaller effect of 13c discrimination for cellulose when compared with wood during decomposition chem geol 158 1999 121 compared with the coals the 13c values of wood and extracted cellulose are affected to a minor extent by microbial activity

organic geochemistry and mineralogy i characterisation of organic matter associated with metal deposits abstract as geochemical appraisals of mineral regions of commercial prospectivity evolve the organic matter associated with metal rich ores has attracted greater attention petroleum basin and modern seafloor hydrothermal vent studies have suggested that organic matter can have a significant influence on the behaviour of mineralising fluids there have been many isolated reports of certain organic compositional or morphological e g pyrobitumen features showing an apparent relationships with hydrothermal fluids or minerals raising expectations that organic based parameters might be useful to mineral exploration however the understanding of organic inorganic relationships in earth systems is far from complete for example the detailed mechanics of the interaction of organics with hydrothermal fluids over geological time remain largely undefined organic geochemistry studies have traditionally involved the measurement and interpretation of the hydrocarbon composition of sedimentary rocks here we review the types of aliphatic hydrocarbons aromatic hydrocarbons and metalloporphyrins often detected from organic geochemical investigations in mineral rich regions such molecular data can be particularly diagnostic of biochemical sources and the palaeo environments at the time mineral associated organic matter was deposited sub surface trends of hydrocarbon alteration may also reflect major biogeochemical processes such as thermal maturity and biodegradation organic geochemistry data can also occasionally provide information about the nature e g origin composition temperatures and migration pathways of hydrothermal fluids and can make a contribution to holistic ore genesis models the well preserved organic matter associated with the economic here s your chance pb zn ag mine paleoproterozoic barney creek formation mcarthur basin australia and the transition metal rich early permian kupferschiefer formation germany poland have attracted significant attention a more detailed summary of the organic character of these deposits is provided to highlight the contribution organic geochemistry can make to understanding mineralisation processes most organic geochemical studies of highly mineralised regions however have not adequately addressed the significance of organic matter to mineralisation a slightly different analytical focus than traditionally used for exploration appraisal of petroleum hydrocarbons may be required to properly evaluate the significance of organic species to the mobilisation transport and deposition of ore metals the characterisation and subsequent thermodynamic modeling of organic substances and complexes within metalliferous hydrothermal systems will contribute to a better understanding of the nature and role of organic inorganic fluids or other affiliated organics in ore systems

paleoenvironment of the upper oligocene trbovlje coal seam slovenia abstract in the trbovlje region slovenia an upper oligocene coal seam up to 30 m thick developed in a topogenous mire and evolved within a transgressive setting the lower ash rich part of the seam unit i accumulated in a forest swamp strongly influenced by fluvial activity palynomorph spectra are dominated by taxodiaceae cupressaceae pollen ash yields decrease in the middle unit ii and upper part of the seam unit iii indicating decreasing fluvial activity an increase in cao contents reflects increasing amounts of inflowing water from an alkaline lake which progressively controlled peat hydrology in units ii and iii high sulfur contents in the nonmarine coal are a result of the carbonate rich water abundant pollen and spores from myricaceae and polypodiaceae indicate that unit ii represents a bush moor during deposition of unit iii this environment was replaced by a reed moor sapropelic coal unit iv and sapropelic shale unit v accumulated in a relatively large lake which was established by another water table rise the interpreted environmental changes are confirmed by biomarker data pristane phytane ratios reflect variations of the redox conditions within the mire and reach a minimum in the sapropelic unit iv the abundances of gymnosperm and angiosperm derived terpenoid hydrocarbons testify the predominance of gymnosperms over angiosperms during early peat stages unit i and increasing proportions of angiosperms during deposition of units ii and iii highest contents of diterpenoids coincide with maxima in the preservation of plant tissue tpi within unit i wet forest swamp suggesting that tpi is partly controlled by the input of resin rich decay resistant conifers sections of the seam characterized by advanced gelification show low steroids hopanoids ratios the results imply that gelification of plant tissue is related to increased microbial activity evidence is provided that the hopanes could be used as a measure for the activity of aerobic bacteria whereas for the hop 17 21 ene a microbial origin from anaerobic iron reducing bacteria is assumed a general influence of the floral assemblage and of varying contributions of algal biomass on carbon isotopic composition of the organic matter 13 c 24 0 to 28 1 is proposed carbon cycling during biogeochemical decomposition of plant tissue by bacteria is assumed to affect the 13 c values of the coal fossil wood collected from the seam is identified as derived from gymnosperms based on the molecular composition of terpenoid hydrocarbons this chemotaxonomical classification is corroborated by the mean carbon isotopic compositions of the fossil wood 13 c 24 0 and by the 13 c value 21 8 of the extracted cellulose from one macrofossil the low cellulose content of the sample 2 7 together with the slightly higher isotopic difference of 1 6 between cellulose and fossil wood compared to that found in modern trees can most probably be explained by the possible reversal in 13 c discrimination for cellulose when compared with wood in highly degraded samples

molecular indicators of palaeoenvironmental conditions in an immature permian shale kupferschiefer lower rhine basin north west germany from free and s bound lipids a study of the distributions of free and s bound biomarkers and their 13c values in the extract of a bulk sample of the permian kupferschiefer from the lower rhine basin has been carried out to provide a more detailed characterization of the biological inputs the distributions and isotopic compositions of selected components released from nickel boride desulphurization have been compared with those of components in the free fraction the free biomarkers occur in greater abundance than their s bound counterparts the distribution and carbon isotopic composition of both free and bound components in the extract indicate a major cyanobacterial and algal input likewise the free and bound aromatic hydrocarbons contain components which reveal an origin from the carotenoids of chlorobiaceae green sulphur bacteria providing molecular evidence for the occurrence of photic zone anoxia in the water column most of the components in the complex mixture of mono di tri and tetra aromatics in the free aromatic hydrocarbon fraction result from cyclization and aromatization reactions

aromatic hydrocarbon composition of the permian kupferschiefer in the lower rhine basin nw germany the aromatic hydrocarbon composition of 25 samples of permian kupferschiefer from the lower rhine basin of nw germany has been investigated using gc gc ms and direct probe ms analysis two narrow sampled profiles were investigated with respect to compositional changes during kupferschiefer sedimentation and samples from 13 different wells covering a depth range from 350 to 1000 m were included in order to study temperature sensitive variations in the kupferschiefer trimethyl substituted aryl isoprenoids in the range from c11 to c21 occur these compounds presumably are degradation products of isorenieratane which is also present in the extracts within the profile the amount of a preferentially occuring c29 chroman increases from the bottom to the top of the kupferscheifer by a factor of about 2 5 the chroman distribution observed in the kupferschiefer points towards euhaline to mesohaline seawater during sedimentation moreover in the investigated profiles a terrestrial source input mainly in the bottom most part of the shale is reflected by the occurrence of a monoaromatic c24 chrysene derivative presumably derived from ring a degradation of pentacyclic triterpenes

organic geochemistry depositional history and hydrocarbon generation modelling of the upper permian kupferschiefer and zechstein limestone strata in south west poland abstract the upper permian zechstein limestone carbonates in the south western part of the polish zechstein basin contain small quantities of organic matter usually less than 0 1 wt toc and have poor hydrocarbon potential in contrast the kupferschiefer shales have excellent hydrocarbon potential with toc as high as 10 8 wt predominantly algal type ii kerogen generally thermal maturity of the organic matter is 0 6 0 9 vitrinite reflectance while locally is as high as 1 45 the kimmerian and laramian tectonic events significantly influenced the regional burial and thermal history the main subsidence of the kupferschiefer zechstein limestone complex took place during the late permian late triassic period with additional burial during the jurassic and late cretaceous hydrocarbon generation from the kupferschiefer source rocks occurred from middle triassic to late jurassic times reaching maximum rates during the jurassic the cretaceous subsidence had only a minor influence on the maturity and transformation of organic matter expulsion started between late triassic in the western part of the study area and early jurassic in the eastern part then ceased by the late jurassic early cretaceous erosion the total amount of generated and expelled hydrocarbons from source rocks was small because their thickness was limited therefore kupferschiefer shales cannot be considered as source rocks for liquid hydrocarbons but may be a potential source for gas accumulated in the zechstein limestone and rotliegend reservoirs

influence of an intrusion on the extent of isomerism in acyclic isoprenoids in the permian kupferschiefer of the lower rhine basin n w germany abstract the intrusive body near krefeld north west germany the so called krefeld high is known to have increased the coalification of the carboniferous coal seams in the western part of the ruhr coal mining district however no evidence of its influence on the partly overlying permian sediments has been given to date therefore organic geochemical investigations on the extractable organic matter from 30 core samples of the permian kupferschiefer covering an area of about 600 km 2 were undertaken the determination of selected molecular maturation parameters reveals a low average maturation of the kupferschiefer within the area investigated locally varying thermal effects could be measured by the extent of isomerism of pristane and phytane in an area not affected by the intrusive body the extent of isomerism is shown to be influenced only by the burial depth and by some minor tectonic events in the proximity of the krefeld high the extent of isomerism is significantly higher than expected from the actual burial depth the extent of pristane and phytane epimerisation have been used to deduce isolines for the characterisation of thermal effects in the area investigated

parameters determining the carbon isotopic composition of coal and fossil wood in the early miocene oberdorf lignite seam styrian basin austria abstract petrographical and geochemical data of gelified and ungelified fossil wood from the early miocene oberdorf lignite seam styrian basin austria provide evidence that the early diagenetic aerobic degradation of wood by fungi may be followed by further decomposition under reducing conditions by the activity of anaerobic bacteria based on the molecular compositions of terpenoid hydrocarbons the wood fragments in the lignite are identified as gymnosperms this result is corroborated by the mean isotopic composition 13c 24 2 of the macrofossils the isotopic difference between fossil wood and extracted cellulose of most samples 3 9 2 5 is higher than in modern trees which can be explained by the smaller effect of 13c discrimination during decomposition of cellulose when compared with wood the mean carbon isotope values found for gymnosperms and coals 24 2 and 24 7 respectively confirm the results from biomarker analyses indicating that the peat forming vegetation of the oberdorf seam was dominated by gymnosperm taxa minor variation in the relative contributions of gymnosperms and angiosperms to coal deposition is of negligible influence on the isotopic composition of the coals cross correlations between 13c of the coals soluble organic matter yield and the proportions of liptinite macerals of higher plant origin imply that the carbon isotopic composition may be affected by the contents of plant lipids because of their 13c values ranging from 5 to 10 less than whole plant tissue values an isotopic shift of the coals towards more negative values due to the activity of prokaryotes i e anaerobic bacteria in organic matter degradation is proposed the results obtained from the early miocene oberdorf lignite indicate that the carbon isotope ratios of the coals are primarily affected by varying contributions of different parts of whole plant tissue due to their different isotopic and molecular compositions e g epicuticular leaf waxes resins wood and their different decay resistance against the early diagenetic changes involved in organic matter decomposition carbon cycling during anoxic decomposition of plant derived organic matter is assumed to affect the 13c values of coal 13c values of wood and extracted cellulose are affected only to a minor extent

depositional environment and hydrocarbon potential of the oligocene menilite formation in the western carpathians a case study from the loucka section czech republic abstract the eocene oligocene boundary in the paratethys area represents a period associated with a major extinction event followed by anoxic events a good understanding of the factors controlling the formation of organic rich layers is a key for prediction of source rock distributions an excellent opportunity to study these factors is provided by the loucka section situated in the silesian unit of the czech republic the menilite formation is subdivided into the subchert member chert member dynow marlstone and sitbo ice member and comprises non calcareous shales marlstones and cherts the lithological variations reflect strongly depositional environment which caused strong changes in geochemical parameters and source rock potential the ratio of total organic carbon to total sulphur toc ts and methylated 2 methyl 2 trimethyltridecyl chroman mttc ratios supported by paleontological evidence show normal marine to brackish water conditions pr ph ratios indicate strictly anoxic conditions during deposition of the upper part of the subchert member and the lower part of the chert member very low steranes hopanes ratios reflect strong bacterial activity during deposition of the chert member very high hi values 600 mg hc g toc and the apparent absence of terrestrial macerals suggest that high amounts of c29 steranes and long chain n alkanes in this member result from the input of algal material the menilite formation contains mainly type ii kerogen and typically holds a good source rock potential hi values 600 mg hc g toc are observed in the chert member while values the source potential index spi of the entire succession of the menilite formation is about 1 25 t hc m2 which is significantly lower than spi determined for the polish and ukrainian carpathians but mainly due to the lower thickness

geochemical and isotopic composition of organic matter in the kupferschiefer of the polish zechstein basin relation to maturity and base metal mineralization vs the present depth of the kupferschiefer soluble organic matter som yields and relative proportions of saturated and aromatic hydrocarbons of the som provide evidence for an oxidative alteration of organic matter in highly mineralized kupferschiefer samples near the rote faule zones this is confirmed by differences in the composition of the saturated and aromatic hydrocarbon fractions of the soluble organic matter saturated hydrocarbons from rote faule samples are dominated by short chain n alkanes and higher abundances of pristane and phytane relative to heptadecane n c17 and octadecane n c18 respectively compared with samples more distant to the rote faule zone compositional changes of the aromatic hydrocarbon fractions with decreasing distance to that zone are characterized by the occurrence of polycyclic aromatic hydrocarbons and elevated ratios of phenanthrene to methylphenanthrenes that are attributed to demethylation reactions and resulted in a decrease of the methylphenanthrene index mpi 1 kupferschiefer samples from the barren zone of the polish basin do not show these alteration patterns the observed variations in organic matter composition with burial depth are consistent with changes due to increasing thermal maturation maturity assessment is achieved from mpi 1 and the methyldibenzothiophene ratio mdr from the relationship between the maturity of organic matter in terms of vitrinite reflectance values and depth of the kupferschiefer strata a continuous increase in reflectance of vitrinite is obtained within the polish basin the alteration pattern of organic matter related to base metal mineralization of the kupferschiefer corresponds to changes in the isotopic composition of organic carbon and calcite kerogen within or close to rote faule zone is enriched in 13c caused by the preferential release of isotopically light organic compounds through progressive degradation of organic matter the opposite tendency towards lower 13c and 18o values of calcite provides evidence for isotopic exchange between carbonate and the oxidizing ore bearing solutions and for organic matter remineralization in contrast organic matter and calcite from the kupferschiefer do not show regular trends in 13c with increasing thermal maturation