novel intact glycolipids in sediments from an antarctic lake ace lake abstract two novel glycolipids docosanyl 3 o methyl rhamnopyranoside and docosanyl 3 o methylxylopyranoside were identified as the most abundant gc amenable components of extracts of sediments of ace lake an antarctic meromictic lake docosanyl 3 o methyl rhamnopyranoside was identified by isolation and high field two dimensional nmr techniques docosanyl 3 o methylxylopyranoside was tentatively identified by characterisation of its sugar moiety by methanolysis and demethylation both glycolipids also have a minor homologue containing a c24 instead of a c22 n alkyl chain stable carbon isotope measurements indicate that the sugar moieties of these glycolipids are ca 8 9 enriched relative to the alkyl chains concentrations increased markedly with depth reaching 2 mg g sediment at 25 cm depth structurally related glycolipids occur in specialised cells of nitrogen fixing cyanobacteria so a cyanobacterial origin is suggested for these sedimentary glycolipids

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

diploptene in antarctic sediments abstract the presence of diploptene 17 h 21 h hop 22 29 ene in sediment cores from bransfield strait and mcmurdo sound antarctica is reported the organic geochemical data for these sediments provide evidence for the authigenic marine origin of this hopene

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

highly isotopically depleted isoprenoids molecular markers for ancient methane venting abstract we propose that organic compounds found in a miocene limestone from marmorito northern italy are source markers for organic matter present in ancient methane vent systems cold seeps the limestone contains high concentrations of the tail to tail linked acyclic c20 isoprenoid 2 6 11 15 tetramethylhexadecane crocetane a c25 homolog 2 6 10 15 19 pentamethylicosane pme and a distinctive glycerol ether lipid containing 3 7 11 15 tetramethylhexadecyl phytanyl moieties the chemical structures of these biomarkers indicate a common origin from archaea their extremely 13c depleted isotope compositions 13c 108 to 115 6 pdb suggest that the respective archaea have directly or indirectly introduced isotopically depleted methane derived carbon into their biomass we postulate that a second major cluster of biomarkers showing heavier isotope values 13c 88 is derived from sulfate reducing bacteria srb the observed biomarkers sustain the idea that methanogenic bacteria in a syntrophic community with srb are responsible for the anaerobic oxidation of methane in marine sediments marmorito may thus represent a conceivable ancient scenario for methane consumption performed by a defined two membered bacterial consortium 1 archaea that perform reversed methanogenesis by oxidizing methane and producing co2 and h2 and 2 srb that consume the resulting h2 furthermore the respective organic molecules are unlike other compounds tightly bound to the crystalline carbonate phase the marmorito carbonates can thus be regarded as cold seep microbialites rather than mere authigenic carbonates

sedimentological and stable isotope evolution of lakes in the vestfold hills antarctica the sedimentological chemical and isotopic characteristics of sediment cores from three slightly saline to hypersaline lakes highway ace and organic lakes and two marine inlets ellis fjord and taynaya bay in the vestfold hills antarctica have been examined sections of the cores deposited in marine environments are characterized by uniform regularly laminated fine grained organic rich sediments with uniform organic 13c values 18 0 to 19 4 vs pdb and sulfur contents in contrast sediments deposited in lacustrine environments are extremely heterogeneous varying from finely laminated mat like sequences to poorly sorted clastic rich sediments authigenic monohydrocalcite and aragonite occur in some lake sediments the 13c values of organic matter in the lacustrine sediments exhibit an extremely wide range 10 5 to 25 3 that can be related to variations in physico chemical conditions in the lake waters strongly negative organic 13c values coupled with high sulfur contents are indicative of an anoxic zone in the overlying lake waters whereas less negative organic 13c values coupled with low sulfur contents are indicative of well mixed oxic conditions particularly high organic 13c values result during high levels of microbial activity in the lakes due to high rates of photosynthetic co2 fixation the large shifts in organic 13c are not necessarily accompanied by any change in macroscopic sedimentological characteristics illustrating the utility of isotopic investigations in these environments the 13c composition of authigenic carbonate in hypersaline organic lake sediments provides a record of changes in palaeoproductivity while the 18o of the carbonate provides information on rates of meltwater input and evaporation in the lake 14c dating suggests that highway lake was isolated from the sea by isostatic uplift at least 4600 yr before present b p whereas organic lake was isolated at approximately 2700 yr b p apparent emergence rates calculated from the 14c ages range from 1 0 to 2 1 mm yr 1 the reservoir effect in the lacustrine and marine environments is variable but probably does not exceed 1000 yr in any of the lakes examined

marine to brackish depositional environments of the jurassic cretaceous suowa formation qiangtang basin tibet china abstract the late jurassic to early cretaceous depositional environments of the qiangtang basin in tibet have the potential to provide significant insight into mechanisms of black shale deposition organic matter accumulation and the timing of closure of the mesotethys ocean however the depositional setting has not been well constrained here we apply multiple geochemical proxies and petrologic analyses to representative samples of black shale marl and micrite collected from a section in the region these indicate a transitional marine continental environment with brackish to saline water redox conditions were weakly oxic to suboxic environments represented by the studied section varied over time the lowermost marls were deposited in a low salinity weakly oxic shore to shallow lake environment under a warm and humid climate regime the micrites in the middle part of the section were deposited in a lagoonal environment with intense evaporation high salinity and water column stratification the uppermost shales were deposited in a reducing semi enclosed lagoon environment during a marine transgression these results suggest that the late jurassic early cretaceous succession was deposited in a tidal flat or lagoonal environment

aliphatic hydrocarbons and triterpenes of the congo deep sea fan abstract hydrocarbons were analyzed in sediments from the congo river deep sea fan from the congo river and in sinking particles collected by sediment traps 40 m above the sediment studied sites encompassed three lobes of decreasing age of formation along the canyon sites a f and c and a another lobe system disconnected from the active channel since 4 ka site e terrestrial long chain odd n alkanes were dominant in all sediments of the lobe system unsaturated terpenoids sourced by higher plants such as gammacerene lupene ursene and oleanene were also detected at site c characterized by high accumulation rates 10 20 cm yr 1 the organic matter spends less time in the oxic layer than at other sites and high phytadiene concentrations 10 17 g g oc 1 evidenced recent terrestrial and phytoplanktonic remains reworked in anaerobic conditions in these sediments organic carbon normalized concentrations of terrestrial alkanes and terpenoids were several fold higher than in the lobe sediments with lower accumulation rates sites a and f arguing for a more rapid degradation of terrestrial hydrocarbons than bulk organic carbon in the first steps of pre diagenesis ample variations in the contributions of biomarkers from higher plants ferns bacteria and angiosperms indicate an heterogeneous contribution of the soil and vegetation detritus delivered to the congo lobe sediments lower concentrations in terrestrial hydrocarbons at site e 45 km away from the active canyon indicated that river particles are still admixed to the dominant marine organic matter diploptene and hop 7 21 ene have a dual origin from terrestrial and marine microorganisms scatter in their relationship to gammacerene argues for a contribution of marine microorganisms in addition to soils sourced microorganisms the close distribution patterns of diploptene hop 21 ene hop 7 21 ene and neohop 13 18 ene is in line with the hypothesis of sequential clay catalyzed isomerisation of bacterial hopenes terrestrial biomarker accumulation fluxes at site c are one order of magnitude higher than vertical pelagic flux demonstrating the magnitude of the inputs delivered through turbiditic transport in the submarine canyon crude oil contamination was evidenced at the disconnected site e ucm c 21 to c 26 tricyclic diterpanes cpi and in smaller amounts in some sediments from sites a and c it may be related to marine crude oil extraction and transport a short chain mode of alkanes with an even predominance is evidenced in sediments of the lobe complex and likely sources crude oil microorganisms and ferns are discussed

the middle eocene markushegy subbituminous coal hungary paleoenvironmental implications from petrographical and geochemical studies abstract samples from two coal seams of the markushegy underground mine hungary were investigated for variations in maceral composition petrography based facies indicators and various geochemical parameters using three seam profiles both seams originate from a topogenous mire and evolved within a peneplaned coastal area covered with eutrophic swamps the presence of foraminifera and marine algae in the marly layers is indicative of marine ingressions coal facies characterisation from these parameters is combined with the results from biomarker analyses of soluble organic matter in order to reconstruct the depositional environment and to relate petrography based indicators to the molecular composition the contents of macerals of the liptinite group are positively correlated with soluble organic matter som yields and hydrogen index hi consistent with maceral composition and high hi values enhanced proportions of n alkanes of intermediate molecular weight n c21 25 which are predominantly found in macrophytes are obtained from samples of the marly shales the final drowning of the mire is reflected by decreasing pristane phytane ratios due to the rise of the ground water table and the establishment of anaerobic conditions the observed positive correlation between pristane phytane ratios and inertinite percentages suggests that at least in the markushegy deposit both parameters reflect variations in redox conditions of the mire the predominance of angiosperms in the peat forming vegetation of the markushegy coal is evidenced by the high relative proportions of angiosperm derived triterpenoids the influence of the relative proportion of fossil wood on tissue preservation tpi is indicated by the positive relationship of the concentration of land plant derived terpenoid hydrocarbons and tpi the degree of gelification of plant tissue gi is governed by the microbial activity in the mire as indicated by a negative relationship between gi and the steroids hopanoids concentration ratios the variation of the 13c values of coal is obviously governed by the relative contribution of plant lipids to the biomass the obtained negative relationship between 13c of the coal and gi is explained by the effect of cellulose decomposition and microbial activity on the isotopic composition of the organic matter

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

bacterial and algal hydrocarbons in sediments from a saline antarctic lake ace lake capillary gas chromatography mass spectrometry c gc ms and iatroscan thin layer chromatography flame ionisation detection tlc fid were used to study hydrocarbon distributions in a sediment core from ace lake a saline meromictic lake in the vestfold hills of antarctica hydrocarbons were abundant in most core sections up to 125 g g dry wt particularly in near surface samples and the distributions were very complex major constituents were identified as phytane 2 6 10 15 19 pentamethyleicosane tetrahydrosqualene a mixture of phytenes cholesta 3 5 diene and fern 7 ene smaller amounts of sterenes and hopenes were also present the predominance of the first 3 acyclic isoprenoids in sediments buried less than 30 cm is consistent with high populations of methanogenic bacteria known to be present phytenes were abundant in all core sections and there was no relationship between their abundance and that of phytane which suggests that they were not derived from methanogenic bacteria phytadienes were minor constituents at all depths studied an unusual feature of some distributions was the high concentrations of fern 7 ene which was the major hydrocarbon in the 20 25 cm core section this alkene was only abundant in sediments which contained high concentrations of methanogen markers suggesting that it may also be indicative of anoxic depositional environments a possible source might be from purple non sulphur bacteria high concentrations of straight chain c29 and c34 alkenes were also found in these sediments but their origin has not been determined major changes in the hydrocarbon distributions with depth indicate that the depositional environment in the lake has altered dramatically since the lake was formed less than 8000 years ago the present condition of permanent anoxic bottom waters probably developed only in the last 1000 years

biomarkers of modern plants and soils from xinglong mountain in the transitional area between the tibetan and loess plateaus abstract organic compounds found in living plants and modern soils in different bioclimatic areas are important in understanding the paleoenvironmental implications of the organic matter signals from geological records using gc ms techniques a series of biomarkers mainly including n alkanes and n alkan 2 ones were identified from the typical plants e g broadleaf deciduous trees and conifers and the soils collected from xinglong mountain a transitional area between tibetan and loess plateaus the c 15 c 33 n alkane homologues were present in all samples typically c 27 or c 29 n alkanes were most abundant in tree samples and c 31 was most abundant in grasses samples meanwhile the soil samples were mainly dominated by c 29 and c 31 homologues the n alkan 2 ones showed a strong odd over even predominance of carbon numbers c 23 c 25 or c 29 n alkan 2 one homologues were most abundant in plant samples while c 27 or c 29 was abundant in soils samples the lipid biomarker distribution patterns of all the plants and soil samples suggest that the vegetation is a primary source of organic matter for the soils and that reprocessing of microbes and physicochemical reactions in the soil played an important role in the degradation of organic matter research has advanced knowledge about transformation of biomarkers in the plants organic matter microbes forest system it also can help reconstruct the process of plant successions recorded by the lipids

algal and bacterial hydrocarbons in particulate matter and interfacial sediment of the cariaco trench particulate matter samples 53 m size fractions and sediment from the sediment water interface were collected in the cariaco trench an anoxic marine basin on the continental shelf of venezuela and analyzed for hydrocarbons concentrations of hydrocarbons were highest 10 20 ng 1 in oxic surface waters 0 150 m and at the top of the anoxic zone 350 600 m and were low 3 4 ng l in the low oxygen zone above the oxic anoxic interface 150 250 m and anoxic bottom waters 600 1150 m branched c25 trienes and tetraenes dominated the hydrocarbon distributions in 53 m particles particle size and depth distributions of the hydrocarbons demonstrate the importance of algal hydrocarbons in surface waters coupled with increased abundances of bacterial hydrocarbons especially in the 53 m particles in the anoxic zone these observations illustrate the importance of oxic anoxic interfaces even in the oceanic water column as zones of intense microbial alteration of organic matter and as sources of some of the organic compounds found in sediments

long chain alkenones and alkyl alkenoates and the fossil coccolith record of marine sediments long chain n c37 c39 alkenones and alkyl alkenoates are biological markers for sediment inputs of algae from the class prymnesiophyceae which includes the coccolithophorids these compounds have been recognized in many recent and ancient marine sediments but in only a few living algal species notably the ubiquitous coccolithophorid emiliania huxleyi the proven value of long chain alkenones in palaeotemperature assessment prompts an evaluation of their sedimentary record especially their correspondence with coccolithophorid fossils in ancient marine sediments synthesis of available micropalaeontological and molecular data suggests that morphologically related species of the genera crenalithus dictyococcites emiliania gephyrocapsa pseudoemiliania and reticulofenestra all belonging to the family gephyrocapsaceae were potential biological sources of alkenones and alkyl alkenoates in marine sediments deposited since the eocene 45 ma the occurrence of alkenones in cenomanian and albian sediments devoid of nannofossils may be presumed to reflect contributions from ancestors of the gephyrocapsaceae although an investigation of cretaceous samples containing both coccoliths and alkenones would provide further evidence of this proposed correspondence the combination of palaeontological and molecular chemotaxonomic information offers a novel approach to the evaluation of the phylogenetic lineages that link living and extinct algae

organic geochemistry of the lower miocene oberdorf lignite styrian basin austria its relation to petrography palynology and the palaeoenvironment abstract in the oberdorf trough at the northwestern margin of the styrian basin austria an up to 36 m thick lower miocene ottnangian lignite seam occurs within the fluvial koflach voitsberg formation previous results indicate that the lignite originated in a topogenous mire within a wet forest swamp palaeoenvironment differences in soluble organic matter som yield of borehole samples from the lignite seam are related to free lipids present in plant waxes or resins and the presence of thermally labile polymers indicated by the contents of liptinite macerals i e resinite suberinite and liptodetrinite the n alkane distribution patterns are dominated by high molecular weight lipids with marked odd over even predominance originating from plant waxes a contribution of algae to the even numbered short chain lipids observed in considerable amounts in the footwall sediments is proposed terpenoid biomarkers characteristic for conifers and angiosperms were detected consistent with palynomorphic spectra which are dominated by forest swamp pollen taxodiaceae cupressaceae and pollen from plants living in a mixed mesophytic forest excellent relationships between higher plant biomarker composition and palynologic data indicate that the organic geochemical results reflect the varying inputs of coniferales vs angiosperms the data further imply that cuparene may be used for taxonomical differentiation of coniferales families organic geochemical data provide evidence that the content of land plant derived biomarkers is controlled by the input of resin rich conifers concentrations of hopanoids dominated by hop 17 21 ene generally increase towards the top of the lignite a section characterised by high extents of aromatisation of triterpenoid biomarkers the results suggest that the aromatisation of angiosperm derived biomarkers may be governed by the activity of anaerobic rather than by aerobic bacteria however changes in the depositional environment and palynologic facies during peat formation probably influenced the origin and fate of angiosperm derived triterpenoids the results indicate how biomarker composition may contribute to the evaluation of environmental changes cross correlations of organic geochemical parameters with palynological data and petrography based facies indicators will provide further insights in the peat forming vegetation and biogeochemical activities in the mire

stereochemical studies of acyclic isoprenoids xii lipids of methanogenic bacteria and possible contributions to sediments abstract abundant volatile lipids of methanobacterium thermoautotrophicum and methanosarcina barkeri include isoprenoid hydrocarbons c30 and c15 c20 and c25 isoprenoid alcohols m barkeri contains 2 6 10 15 19 pentamethyleicosane whose relative stereochemistry is the same as found in marine sediments indicating that it is a marker of methanogenic activity the c20 c30 and c25 alkenes in m thermoautotrophicum also have a preferred sterochemistry the latter have the 2 6 10 14 18 pentamethyleicosanyl skeleton suggesting that the alkane in marine sediments may derive from methanogens the stereochemistry of squalane in a marine sediment is also compatible with an origin in methanogens in contrast the stereochemistry of pristane in m thermoautotrophicum indicates a fossil fuel contaminant origin suggesting that this and certain other alkanes reported in archaebacteria might also be of contaminant origin there is therefore little evidence at present that the pristane in immature marine sediments originates in methanogens the c15 and c20 saturated alcohols in m thermoautotrophicum have mainly the all r configuration if this is generally true for methanogens the c20 alcohol in the messel shale may originate mainly from methanogens whereas that in the green river shale may originate mainly from photosynthetic organisms

contrasting watermass conditions during deposition of the whitby mudstone lower jurassic and kimmeridge clay upper jurassic formations uk abstract the whitby mudstone formation wmf and kimmeridge clay formation kcf are both jurassic organic rich black shale units containing well preserved marine organic matter despite such gross similarities they exhibit opposite trends in 13 c toc versus wt decarbonated total organic carbon toc r 0 76 for wmf and 0 71 for kcf the 13 c toc versus toc trend also varies geographically within both units only the kcf data exhibit a positive correlation between 13 c toc and 15 n org r 0 76 and the presence of aryl isoprenoids probable indicators of photic zone anoxia maturity differences are insufficient to explain such contrasts bulk and compound specific isotopic variations in the kcf are interpreted largely as a reflection of primary productivity during deposition rather than a dominantly diagenetic signal due to incorporation of sulphurised carbohydrate the contrasts between the formations and the geographic variation in coeval shelf sediments are explained by a model stressing the relative positions and stabilities of the chemocline pycnocline nutricline and euphotic zone and the effect these have on productivity co 2 recycling and bacterial floras

gc ms detection and significance of crocetane and pentamethylicosane in sediments and crude oils abstract the occurrence of the archaeal biomarkers crocetane and pentamethylicosane pmi in sediments and crude oils was investigated using gc ms and gc ms ms selected ion monitoring sim and multiple reaction monitoring mrm protocols designed to detect the c 20 and c 25 irregular isoprenoids were evaluated a method for the preferential detection of crocetane over phytane its more abundant isomer was refined using authentic compounds crocetane was found to be present in modern sediments from both aerobic and anaerobic water columns and in sediment from the 1640 ma barney creek formation providing evidence for the antiquity of its biosynthesis crocetane was also detected in several perth basin crude oils and in the kockatea shale their putative source rock and in canning basin oils although mrm analysis could only verify its occurrence in canning oils of devonian age equivocal data from ordovician and carboniferous canning basin oils highlight the need for extreme caution when attempting to distinguish between acyclic isoprenoid isomers pmi was identified by mrm in a miocene monterey sediment and in a modern antarctica sediment on the other hand the c 25 isoprenoid hydrocarbon peak detected in triassic and older sediments was consistently identified as the regular isomer i 25 reg whenever it was sufficiently abundant for mrm to be applied

paleogeography and paleoecology of the upper miocene zillingdorf lignite deposit austria abstract the zillingdorf deposit formed during the late miocene filling of lake pannon and contains austria s largest lignite reserves two lignite seams are present and developed within frequently flooded low lying mires in near shore environments high sulphur contents are due to the influence of the brackish water body of lake pannon during peat accumulation a transgression forced the nw se trending shoreline northeastwards differences in soluble organic matter som yield and hydrocarbon content of borehole samples and woody macrofossils are related to differences in the content and composition of free lipids of microbial origin and or hydrocarbons derived from the biogeochemical degradation of plant tissue variations of pristane phytane ratios are interpreted to reflect differences in the redox conditions of the mire peatification in an acidic and aerobic environment is further reflected by the predominance of aromatic over saturated hydrocarbons the presence of an intense complex mixture in the gc traces due to biodegradation processes high ratios for diasterenes relative to sterenes and high concentration ratios of hopanes to hop 17 21 ene of the respective samples gelification of plant tissue is governed by microbial activity as indicated by the positive relationship between gelification index and hopanoids concentration the composition of terpenoid biomarkers indicates the predominance of gymnosperms over angiosperms and increasing proportions of angiosperms in the peat forming vegetation with decreasing depth in the upper seam from the sesqui and diterpenoids present in the lignite and fossil wood remnants a predominant role of species of the coniferales families cupressaceae taxodiaceae are concluded the preservation of plant tissue is governed by the presence absence of decay resistant gymnosperms a general influence of the floral assemblage on the isotopic composition of organic carbon of the lignite 13c 27 2 to 24 6 is proposed decomposition of plant tissue and biogeochemical carbon cycling is assumed to further affect the 13c values of the lignite carbon isotope data of fossil wood remnants are consistent with their chemotaxonomical classification as gymnosperms 13c between 22 5 and 24 9 and angiosperms 13c between 25 5 and 26 6 respectively the 13c data of the extracted cellulose reveal clear differences between fossil wood from gymnosperms average 13c 20 3 and angiosperms mean 13c 22 9 the higher isotopic difference of about 3 5 between cellulose and fossil wood compared to that found in modern trees is explained by the smaller effect of 13c discrimination for cellulose when compared with wood during decomposition

aquatic biomarkers record pleistocene environmental changes at paleolake olduvai tanzania abstract several hypotheses invoke climatic variability as a driving force for hominin evolution thus high resolution records of climate and environmental variability from anthropologically significant locations can help test these hypotheses sedimentary sequences recovered by the olduvai gorge coring project ogcp help evaluate climatic and environmental changes at olduvai gorge tanzania through the analyses of various biogeochemical proxies the stratigraphic sequence of ogcp core 2a can be correlated with horizons associated with hominins and is chronologically constrained by distinctive dated horizons such as the bed i basalt and tuff ib the lacustrine interval from 76 6 to 86 9 m depth is ideally suited for high resolution analyses of biogeochemical proxies as it is rich in organic carbon 1 toc the hydrogen isotopic composition of nc31 in this interval of ogcp core 2a records the effects of precession driven wet dry cycles on the terrestrial environment that led to alternations between woodland and grassland ecosystems comparable to those documented by previous investigations of outcrop analogues at olduvai here we examine stratigraphic variations in the abundance of biomarkers c28 steradienes c17 and c23 n alkanes c27 and c28 a norsteranes fern 8 ene and chromans derived from aquatic organisms algae cyanobacteria sponges macrophytes etc to determine the response of paleolake olduvai to climate variability in general these aquatic biomarkers reflect the productivity of the lake environment and exhibit the same precession driven wet dry cycles recorded by terrestrial biogeochemical signatures however they also provide evidence of abrupt

organic geochemistry of marine sediments in antarctic region marine lipids in mcmurdo sound abstract the compositions of resolvable lipid components from four sediment cores 0 90 cm of mcmurdo sound ross sea have been examined the various lipid components occur in the following order of abundance sterols fatty acids n alcohols n alkanes pah the data indicate that the organic matter is mainly derived from recycled kerogen mixed with modern marine input the distribution of lipids and lignin analyses indicate that there is little recognizable higher plant debris in the sediments the sediments contain unaltered biogenic triterpenoids and there is no evidence for natural and or anthropogenic petroleum influx in the region aeolian transport of organic carbon from the continents appears to be negligible the dominance of labile alkenes c 25 compounds and hopenes and the presence of unsaturated fatty acids down to a depth of 90 cm reflect a very early diagenetic stage the persistent cold climate has probably helped in the better preservation of these labile lipids in the water column and in the young sediments diploptene 17 h 21 h hop 22 29 ene appeats to originate from autochthonous marine productivity in mcmurdo sound

origin and tentative identification of tri to pentaunsaturated ketones in sediments from lake fryxell east antarctica abstract chromatographic and mass spectrometric analysis of surface sediments from perennially ice covered lake fryxell mcmurdo dry valleys east antarctica enabled tentative identification from mass spectral data of previously unreported pentaunsaturated ketones octatriacontapentaen 2 one c38 5me nonatriacontapentaen 3 one c39 5et and tetradecapentaen 2 one c40 5me in addition the c37 c38 and c40 alkenones occur as di tri and tetraunsaturated compounds whereas the c39 alkenones only include the tetraunsaturated components analysis of environmental dna extracted from the water column of lake fryxell produced two 18s rdna sequences closely related to isochrysis spp chrysotila lamellosa and haptophyte sequences previously recognized in sediment samples collected from a greenland lake and from ace lake antarctica based on the alkenone distribution coupled with phylogenetic data we propose that haptophytes related to isochrysis and or c lamellosa are the source organisms of alkenones in lake fryxell the occurrence of pentaunsatured alkenones may represent a response to the year round cold water temperature ca 1 c average likely combined with oxygen supersaturation and growth under light and nutrient limited conditions in the upper water column

the problem of boundaries in defining ecosystems a potential landmine for uniting geomorphology and ecology forging stronger linkages between geomorphology and ecosystem ecology depends in part upon developing common conceptualizations of an ecosystem because most ecosystem processes are scale dependent the choice of boundaries is of profound importance to the conceptualization of an ecosystem and to the scope and validity of questions being asked within that ecosystem indeed any conceptualization of an ecosystem requires constraining the spatial and temporal scales of analysis thus it is of particular importance to match the ecosystem boundaries to the question being asked or to the processes being studied and to facilitate better communication among disciplines to be explicit in the definitions adopted for an ecosystem defining an ecosystem can be problematic when the processes of interest operate at potentially different scales and little research exists comparing scales of geomorphic processes with those of ecological processes here we will discuss the importance of scale in geomorphic and ecological research and compare and contrast disciplinary biases and inclinations to highlight the problem of conflicting spatial scales we will draw on recent attempts to link the structure of food webs to measures of ecosystem size in particular problems arise where little or no strong association exists among community membership resource supply and physical boundaries similar problems arise when trying to link geomorphologic and ecological processes that can operate at different but variable temporal scales

relationships between coal quality and organic geochemical parameters a case study of the hafik coal deposits sivas basin turkey abstract this study provides coal quality organic petrographic and organic geochemical data on tertiary subbituminous coal of the hafik area northwestern part of the sivas basin turkey coal petrological studies along with proximate and ultimate analyses were undertaken to determine the organic petrographic characteristics of the hafik coals huminite reflectances were found to be between 0 38 and 0 48 corresponding to an organic material rich and coal layers values characteristic of low maturity this parameter shows a good correlation with calorific values average 21 060 kj kg and average t max 422 c mineral matter diagenesis indicating immaturity the studied coals and organic material underwent only low grade transformation a consequence of low lithostatic pressure therefore the hafik coals are actually subbituminous in rank rock eval analysis results show types ii iii and iii kerogens the organic fraction of the coals is mostly comprised of humic group macerals gelinites with small percentages derived from the inertinite and liptinite groups in this study organic petrographic organic geochemical and coal quality data were compared the hafik deposit is a high ash high sulfur coal the mineral matter of the coals is comprised mainly of calcite and clay minerals

saturated and olefinic hydrocarbons in recent sediments from the baltic sea abstract saturated and olefinic hydrocarbons in the top sections of contemporary sediments from four stations in the baltic sea teili 1 f 81 eb 1 and xv 1 were analysed by capillary gas chromatography and gc ms techniques the 0 2 2 4 4 5 and 10 11 cm sections showed a small unresolved complex mixture ucm however in all these sections a strong predominance of odd over even carbon numbered compounds exists indicating an insignificant petroleum hydrocarbon input in the areas studied the resolved hydrocarbons are of mixed marine autochthonous and terrigenous origin the 0 5 cm sections contained the highest proportions of short chain and branched chain hydrocarbons derived mostly from algae and bacteria in general an increase was observed in the ratios of saturated to unsaturated and of longer chain to short chain hydrocarbons with increasing depth because of the facile diagenesis of unsaturated components and faster biodegradation of short chain hydrocarbons in addition between one and seven hydrocarbons the exact structure of which could not be assigned were detected in the samples most of these components were cyclic and unsaturated and a number were triterpenes

organic geochemical characteristics and accumulation of the organic matter in the jurassic to cretaceous sediments of the saihantala sag erlian basin china abstract the organic petrology and organic geochemistry of jurassic to cretaceous hydrocarbon source rocks from the saihantala sag the erlian basin have been analyzed to determine their geochemical characteristics hydrocarbon potential and organic matter accumulation the mudstones of the alatanheli formation j1 2al the aershan formation k1ba the lower tengger member k1bt1 and the upper tengger member k1bt2 and the saihantala formation k1bs contain variable total organic carbon concentrations and organic matter type the observed macerals in the j1 2al k1ba k1bt1 and k1bt2 mudstones are sapropelinites including lamalginites mineral bituminous groundmasses and rare telalginites vitrinites and inertinites in order of abundance whereas vitrinites and inertinites are the predominant macerals in the k1bs mudstones the vitrinite reflectances are lower than 0 7 in the studied samples suggestive of their low organic maturity which is consistent with the strong yellow fluorescence of the lamalginites and telalginites low tmax values the presence of 17 h 21 h hopanes and hop 17 21 enes and aliphatic and aromatic thermal maturity parameters the studied samples were mainly deposited under anoxic saline lake environments the major biological sources in the j1 2al k1ba k1bt1 and k1bt2 mudstones are bacteria and algae whereas higher plants are the more important biological source in the k1bs mudstones as indicated by biomarkers and maceral contents the j1 2al k1ba k1bt1 and k1bt2 mudstones mainly have more capacity to generate oil than gas whereas the k1bs mudstones are mainly gas prone despite the low thermal maturity of the studied mudstones abundant oil has been found in the southeast of the saihantala sag with mature source rocks the nature of their generated products was due to their different formation mechanisms of organic matter accumulation the organic matter accumulation in the j1 2al k1ba k1bt1 and k1bt2 mudstones was controlled by the high primary productivity and anoxic conditions whereas the formation of the k1bs organic rich sediments was mainly related with a high influx of higher plants

biomarker and stable carbon isotope systematics of fossil wood from the second lusatian lignite seam of the lubstow deposit poland abstract decay of fossil wood gelification collected from the middle miocene 2nd lusatian lignite seam at the lubstow open cast mine poland is characterised by its maceral variety fluorescence intensity and cellulose content cellulose decomposition leads to lower molar h c ratio values of the organic matter as indicated by higher total organic carbon toc content of samples characterised by low cellulose content biochemical formation of hydrocarbons in the wood due to enhanced microbial activity is evidenced by higher hydrocarbon content in the extracts higher relative proportions of n alkanes and hopanoids are observed in the hydrocarbon fractions of wood remains characterised by low cellulose yield the results provide evidence for the formation of these compounds during biogeochemical transformation of organic matter hopanoid contents are considered to reflect the activity of aerobic bacteria and or fungi because of enhanced perylene content in the hydrocarbon fractions from gelified wood samples fungi are considered as the major precursor carriers of this polycyclic aromatic hydrocarbon the results provide evidence that biomarker composition of fossil wood can be used to trace biochemical transformation processes chemotaxonomical classification of fossil wood fragments as gymnosperms most probably species of the coniferales families taxodiaceae cupressaceae are based on the molecular composition of terpenoid hydrocarbons and a mean 13 c value of 24 5 depletion of gelified samples in 13 c as compared to ungelified wood is caused by the effect of progressive decomposition of cellulose the data indicate that cellulose 13 c data mean 13 c 20 8 are also affected by wood decomposition and so only samples with comparable cellulose content should be used for the reconstruction of environmental changes inter species as well as intra plant variation in carbon isotope differences and of decay resistance between cellulose and lignin have to be taken into account

vegetation differences and diagenetic changes between two bulgarian lignite deposits insights from coal petrology and biomarker composition abstract during the miocene numerous sedimentary basins formed on the territory of bulgaria as a result of the extensional tectonic settings related to the post orogenic development of the late alpine orogen in this study we review the petrographic composition and biomarker assemblage of two adjacent basins in western bulgaria i e beli breg and staniantsi basins both contain lignite formed during late miocene c 6 ma despite similar tectonic settings and depositional environments the lignite seams possess different petrographic and organic geochemical characteristics reflecting differences in the peat forming palaeo communities and facies variations the peat forming vegetation in beli breg basin was dominated by decay resistant coniferous plants as indicated by abundant fossil wood remains very good tissue preservation and a biomarker assemblage dominated by diterpenoids in contrast staniantsi lignite is poor in fossil wood and contains a significant amount of triterpenoid biomarkers suggesting the predominance of angiosperm plants in the swamp the results of the biomarker analyses are consistent with palaeobotanical and palynological data from the literature the lignite seams in both basins formed under frequently changing eh conditions as indicated by the severe degradation of the non gymnosperm tissues the low gelification index values and the variations in pristane phytane ratio probably as a result of seasonal drying of the swamps and changes of the ground water table hopanoid contents in beli breg lignite are very low and are consistent with the abundance of decay resistant vegetation in contrast bacterial activity was obviously higher in the staniantsi swamp however resulting only in slightly enhanced gelification of plant tissues the geochemical data suggest that the diagenetic changes of the organic matter were mainly governed by thermal degradation rather than bacterial activity

high frequency floral changes at the paleocene eocene boundary revealed by comparative biomarker and palynological studies abstract the cap d ailly area upper normandy france shows several terrestrial lagoonal sections recording the negative carbon isotope excursion cie associated with the paleocene eocene thermal maximum petm 55 8 ma a study of the biomarkers and spore pollen content of the vasterival section gave complementary information on paleofloral changes that occurred around the paleocene eocene p e boundary aliphatic hydrocarbon fractions revealed a high abundance of vascular plant biomarkers including tricyclic diterpanes derived from conifers fernenes derived from ferns and des a triterpenes derived from angiosperms whereas the vegetation of the depositional environment surroundings seemed alternately dominated by ferns and angiosperms revealed from biomarkers the regional flora seemed dominated strictly by angiosperms such as juglandaceae revealed by pollen spore pollen assemblages revealed no major turnover in the paleovegetation but slight variation in vegetation composition however both biomarkers and spores pollen exhibited two intervals of rapid floral change the first occurred around the p e boundary and the second at the top of the strictly terrestrial unit that coincides with a marine transgression comparison of the data with published paleoclimatic results obtained from the same samples indicated that the first interval of floral change correlates with strong paleohydrological perturbations whereas the second is linked to an increasing marine influence

pre and post industrial environmental changes as revealed by the biogeochemical sedimentary record of drammensfjord norway the biogeochemical sedimentary record of the anoxic drammensfjord norway was investigated on a decadal to centennial time scale over the last millennium in order to reconstruct the pre industrial fjord environment and ecosystem and human induced environmental changes the sediments were dated by a combination of 14c and 210pb analysis and varve counting analysis of the bulk sedimentary parameters and of the biomarker distribution revealed that the sedimentary organic matter of the fjord is primarily of terrigenous origin indicating that the fjord was oligotrophic or mesotrophic the fjord s bottom water has been continuously euxinic since at least 1000 ad but photic zone euxinia occurred only irregularly in the fjord the organic matter flux and composition remained virtually invariable until the 18th century after that time the flux of material derived from coniferous trees started to increase indicated by elevated concentrations of dehydroabietic acid and related compounds but also by raising levels of c24 n alcohols and fatty acids this marked the onset of sawmill activities in the hinterland after the beginning of the industrial revolution around 1850 the flux of organic waste from sawmills and paper mills increased substantially it is suggested that slow bacterial degradation of this relatively nutrient poor organic waste caused a gradual eutrophication trend which is reflected in substantial increased bacterial and moderately increased other aquatic biomarker accumulation rates after the industrial revolution this trend accelerated and was possibly enhanced by a growing population of the area with accompanying agricultural and domestic waste this promoted primary productivity and changed the phytoplankton composition in the fjord

the guianese paradox how can the freshwater outflow from the amazon increase the salinity of the guianan shore french guiana is notable for the extent of its rain forests which occupy 97 of the country and the influence of the amazon along its shores in fact the shores and estuaries support a mangrove forest typical of saline conditions this paper reports the chemical characteristics conductivity and salinity and the stable isotopes oxygen and deuterium of the rivers and shores between the cayenne area and the border with surinam the results show a quite homogenous freshwater pool over the country however the low slope of the coast a result of the wide mud banks deposited by the amazonian plume have turned the mouths of the smaller rivers to the northwest creating large salty areas where mangroves grow several kilometers inland despite the large amount of amazonian water the guianan coast exhibits high salinity in fact the freshwater itself remains far from the shore following the north brazilian current while only the mud plume arrives at the coast creating this paradox

biogeochemical evidence from ogcp core 2a sediments for environmental changes preceding deposition of tuff ib and climatic transitions in upper bed i of the olduvai basin abstract sediment cores recovered by the olduvai gorge coring project ogcp in 2014 afford the opportunity to examine the coupling of biogeochemical evidence for climatic and environmental change within the context of hominin evolution at this renowned east african locality investigations of elemental total organic carbon toc or corg wt carbon to nitrogen ratio c n molecular source specific biomarkers and isotopic 13corg 2hnc31 compositions of organic matter provide evidence for temporal changes in sedimentary materials derived from terrestrial plants c3 c4 and aquatic producers algae sponges cyanobacteria and in precipitation the 13 kyr record of upper bed i immediately preceding tuff ib extends high resolution stratigraphic profiles of precession scale alternations of wetter and drier conditions to encompass the entire interval from the bed i basalt to tuff ib the second wetter interval designated w2 records local influences on climate and water supply consistent with evidence for discrete sediment sources based its physical properties e g gamma radiation magnetic susceptibility compared with the overall sequence the 13ctoc values for wetter interval w2 reveal two millennial scale 2 5 kyr drier episodes followed by a shift in the dominance of c3 over c4 plants accompanying the transition to a drier climate d3 moreover biogeochemical data for upper bed i show that changes from drier to wetter conditions occur more rapidly 900 yr than wetter to drier transitions 2 6 kyr based on interpolated ages in addition biomarker profiles indicate that aquatic plants primarily algae and macrophytes may have been subject to more profound and faster fluctuations than variations in terrestrial vegetation expressed in terms of the relative proportions of woodland and grassland settings thus environmental and climatic changes not only influenced the availability of resources of food and shelter for hominins within the olduvai region but also led to their variation on centennial to millennial to precessional timescales

molecular composition of a leaf and root bearing oligocene oxbow lake clay in the weisselster basin germany abstract a plant fossil bearing clay profile from the upper oligocene thierbach strata weisselster basin germany has been sectioned into horizons and the plant macrofossils of each section surface have been identified by morphological and anatomical studies in the upper half of the profile leaves from populus germanica and carpinus grandis and branchlets from the conifer taxodium balticum vel t dubium dominate the horizons while the lower part contains only root remains of unknown higher plants in the soxhlet extracted samples from each section n alkanes n alkanols n carboxylic acids and several terpenoids amyrin 24 25 dinoreleana 1 3 5 10 12 tetraene olean 12 en 3 one simonellite and hop 17 21 ene were identified by combined gas chromatography mass spectrometry the comparison of the extracted chemical compounds and the macrofossil record of the profile shows that simonellite occurs preferentially in the taxodium bearing horizons n alkanes n alkanols n carboxylic acids and amyrin were found in all sections but are enriched in the root containing part of the profile the distribution of hop 17 21 ene is independent of the input of higher plant remains

the role of calcareous and shaly source rocks in the composition of petroleum expelled from the triassic shublik formation alaska north slope abstract for nearly thirty years the triassic marine carbonate shublik formation has been suggested and confirmed as a key source rock for hydrocarbons in the north slope of alaska the formation accounts for roughly one third of the oil in the supergiant prudhoe bay field and for nearly all of the oil in the second largest kuparuk river field recent studies of oil types in the vicinity of the northstar field suggested presence of shaly organofacies of the shublik formation based on the likely triassic age and marine shale biomarker signatures of some analyzed oil samples the current work fills the gap between biomarker analysis of predicted calcareous and shaly oil types and source rock geochemistry biomarker based oil source rock correlation confirms the presence of two genetically distinct organofacies and related oil families both groups were deposited under a similar redox condition anoxic to suboxic with dominantly marine algal input but in either 1 a clay rich or 2 a clay poor depositional setting chemometric evaluation of multivariate biomarker data reveals mixtures with variable degrees of mixing between end members analysis of diamondoids confirms mixed oil types and establishes diamondoid signatures of source rock end members this allows for correlation of biomarker poor overmature shublik source rock samples to oils and extends these interpretations over large areas of the north slope

variability in coal facies as reflected by organic petrological and geochemical data in cenozoic coal beds offshore shimokita japan iodp exp 337 abstract this study reports on cenozoic coal seams recovered at integrated ocean drilling program iodp site c0020 during expedition 337 iodp site c0020 is located in a forearc basin formed by the subduction of the pacific plate off shimokita peninsula japan hole c0020a penetrated 14 coal layers between 1825 and 2466 mbsf eleven of them were investigated within the frame of this paper investigated seams show a slight maturity increase with depth from lignite to sub bituminous coal in order to detect temporal changes in maceral and molecular composition and to relate them to changes in vegetation and depositional environment macro and micropetrographic data bulk geochemical parameters biomarker analysis stable isotope geochemistry and vitrinite reflectance measurements were performed results were also compared with palynological data obtained from 9 coal samples elevated sulfur contents and high ash yields occur in the upper seams cores 14r to 18r whereas low sulfur contents and varying ash yields were determined for the lower coal seams 24r to 30r the maceral composition and biomarker ratios of the uppermost seams argue for coal formation in a paralic environment and brackish alkaline water conditions in contrast lignite samples from the lower part of unit iii point to a limnic fluviatile deposition conifers contributed significantly to peat formation in the uppermost seams from cores 15r to 22r and in the lowermost lignite seam in all other samples angiosperms are considered as the major peat forming plants the pollen and spore floras indicate rich angiosperm vegetation however significant contributions from pinaceae and taxodiaceae are evident for all coals sporophytes have no dominant influence on the coal flora microbial activity in the peat is suggested for instance by higher concentrations of hop 17 21 ene with increasing contents of hopanes or by low 13 c values of hop 17 21 ene the revealed changes in the environment during coal deposition highlight the importance of combined organic petrography organic geochemistry and palynology to reconstruct palaeoenvironmental conditions

organic geochemistry of the mcmurdo dry valleys soil antarctica abstract organic geochemical studies of 12 soil samples from wright and taylor valleys of the mcmurdo dry valleys ross desert in southern victoria land antarctica were carried out long chain n alkanoic acids c 20 c 34 with predominance of even carbon numbers were abundant in all the samples 3 hydroxy acids c 8 c 30 with a predominance of even carbon numbers were found in the samples together with 2 and 1 hydroxy acids dicarboxylic acids c 8 c 31 were detected having near unity values of carbon preference indices mainly the c 13 dicarboxylic acid predominated visual kerogen revealed that amorphous materials are major components 68 98 with small amounts of very fine coals 2 32 but no woody and herbaceous materials the occurrence of mature isomers of steranes and triterpanes the paucity of n alkenoic acids and data from the microscopic study suggest that organic components in the soil samples are derived from erosion of beacon supergroup sedimentary rocks and past biological debris containing vascular plan waxes as well as wind transported cyano bacterial mats including cyanobacteria microalgae bacteria and fungi rather than from living organisms

faunal microfossils indicators of holocene ecological change in a saline antarctic lake abstract the sediment record of the fauna of ace lake a saline meromictic lake in the vestfold hills antarctica consists of copepod eggs spermatophores and exoskeletal fragments rotifer and tintinnid loricae and foraminiferal and folliculinid tests the relative abundance of these remains along with other characteristics of the core allows the development of a coherent picture of the progress of ace lake from a species poor freshwater lake early in the holocene to a biodiverse marine basin following a marine transgression subsequent sea level fall reformed ace lake as a saline lake and productivity initially increased after isolation after a major event possibly associated with overturn of the meromictic lake biodiversity and productivity decreased and have continued to do so until the present

combined dna and lipid analyses of sediments reveal changes in holocene haptophyte and diatom populations in an antarctic lake preserved ribosomal dna of planktonic phototrophic algae was recovered from holocene anoxic sediments of ace lake antarctica and the ancient community members were identified based on comparative sequence analysis the similar concentration profiles of dna of haptophytes and their traditional lipid biomarkers alkenones and alkenoates revealed that fossil rdna also served as quantitative biomarkers in this environment the dna data clearly revealed the presence of six novel phylotypes related to known alkenone and alkenoate biosynthesizing haptophytes with isochrysis galbana uio 102 as their closest relative the relative abundance of these phylotypes changed as the lake chemistry particularly salinity evolved over time changes in the alkenone distributions reflect these population changes rather than a physiological response to salinity by a single haptophyte using this novel paleo ecological approach of combining data from lipid biomarkers and preserved dna we showed that the post glacial development of ace lake from freshwater basin to marine inlet and the present day lacustrine saline system caused major qualitative and quantitative changes in the biodiversity of the planktonic populations over time

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

relations of petrographical and geochemical parameters in the middle miocene lavanttal lignite austria abstract samples from two lignite seams lower seam upper seam of the lavanttal basin austria and additional xylite were investigated for variations in maceral composition petrography based facies indicators bulk geochemical parameters and molecular composition of hydrocarbons both seams originated in a topogenous mire and evolved within a transgressive setting the final drowning of the mire is indicated by sapropelic shales whereas the sapropelic shale overlying the lower seam was deposited in a freshwater lake the sapropelic shale above the upper seam represents a brackish lake numerous relationships are found between petrography based facies indicators and the geochemical composition of organic matter the contents of macerals of the liptinite group are positively correlated with soluble organic matter som yields and hydrogen index hi consistent with maceral composition and high hi values enhanced proportions of short chain n alkanes which are predominantly found in algae and microorganisms are obtained from samples of the sapropelic shales the final drowning of the mire is reflected by decreasing pristane phytane ratios due to the rise in ground water table and the establishment of anaerobic conditions as well as by decreasing ratios of diasterenes sterenes indicating increasing ph values in the mire the degree of gelification of plant tissue gelification index is governed by the microbial activity in the mire as indicated by the hopanes concentration the differences in floral assemblage during the formation of the lavanttal lignite seams are reflected by major differences in tissue preservation preservation of plant tissue tpi in the lavanttal lignite is obviously controlled by the presence absence of decay resistant gymnosperms in the peat forming vegetation and additionally influenced by the relative contribution of wood to coal formation the results provide evidence that valuable information for coal facies characterization could be obtained by petrography based and geochemical facies indicators an influence of the floral assemblage gymnosperms angiosperms ratio and of the contribution of algal biomass on carbon isotopic composition of the organic matter 13c 24 2 to 28 6 is proposed carbon cycling during biogeochemical decomposition of plant tissue by bacteria is suggested to affect the 13c values of the coal the chemotaxonomical classification of the xylites as gymnosperm remnants based on the molecular composition of terpenoid biomarkers is corroborated by the carbon isotopic composition of the xylites mean 13c 24 1 and the extracted cellulose mean 13c 20 2 the higher isotopic difference of about 3 9 between cellulose and total organic carbon of the xylites compared to the difference between cellulose and wood found in modern trees is explained by the smaller effect of decomposition on 13c of cellulose

anaerobic bacterial degradation of pristenes and phytenes in marine sediments does not lead to pristane and phytane during early diagenesis abstract anaerobic degradation of mixtures of isomeric pristenes and phytenes by sedimentary bacterial communities was investigated these isoprenoid alkenes were quickly metabolized without formation of the corresponding alkanes identification of several bacterial metabolites allowed us to confirm the key role played by hydration in the metabolism of alkenes despite the increasing production of 5 stanols during incubation attesting to the involvement of biohydrogenation this process did not act significantly on the double bond of pristenes and phytenes their resistance is attributed to the lack of binding polar group s to anchor the substrate to the enzyme and thus allow the double bond to reach the reductive catalytic site it therefore seems that microbial hydrogenation of pristenes and phytenes does not account for the presence of pristane and phytane in recent sediments during early diagenesis

branched alkanes from ancient and modern sediments isomer discrimination by gc ms with multiple reaction monitoring abstract linked scanning of a tandem sector mass spectrometer has been used to identify abundant first field free region ffr1 unimolecular fragmentations in branched and isoprenoid hydrocarbons the most intense structure specific reactions were selected to establish multiple reaction monitoring mrm parameters for gc ms analysis this methodology has been used to study the identity of co eluting and closely eluting hydrocarbon biomarkers from modern and ancient sediments anand from extant micro organisms some sediments of cambrian and proterozoic age have been found to contain suites of monomethylalkanes with all possible isomers present and with little apparent preference for the site of branching

spatial and temporal variability in vegetation and coal facies as reflected by organic petrological and geochemical data in the middle miocene cayirhan coal field turkey abstract coal channel samples of middle miocene age are collected from the first tv and second tb seams from underground mines and from exploration boreholes within the cayirhan coal field in the beypazari basin turkey they are investigated in order to detect spatial and temporal changes in maceral and molecular composition of coal and to relate them to changes in vegetation and depositional environment the mean random reflectance values of ulminite 0 40 rr indicate a lignite to subbituminous c coal in rank maceral composition and biomarker ratios of the samples from both seams at the cayirhan deposit argue for coal formation in a limno telmatic environment under dysoxic to anoxic conditions alkaline surface waters of changing ph values and a high and unstable water level at the palaeomire are evidenced by moderate to high gelification index gi and ground water influence gwi values as well as high sulphur contents variations in tissue preservation index tpi and vegetation index vi values point to minor variations in the palaeovegetation during peat formation herbaceous plants dominated in both tb and tv palaeomires low tpi and vi values whereas in the surroundings arboreal vegetation were predominant the decreasing trends in pristane phytane ratios and carbon preference index cpi values towards the ne are suggested to reflect oxygen deficient conditions during peat formation due to a higher ground water level in this part of the basin the occurrence of c 29 diasterenes in low abundances provides evidence for periods of lower ph in the mire the borehole samples from the ne show slightly enhanced contributions of n alkanes from algal and microbial sources the terpenoid hydrocarbons present in the lignite argue for a major contribution of angiosperms to peat formation and slightly enhanced proportions of gymnosperms in the tv palaeomire in the ne based on the high concentrations of lupane type triterpenoids in the coal seams from the underground mine a higher density of betulaceae in the arboreal vegetation in the sw is indicated

depositional environment of the late miocene hausruck lignite alpine foreland basin insights from petrography organic geochemistry and stable carbon isotopes abstract lignites and fossil wood from two boreholes in the late miocene hausruck district alpine foreland basin austria were investigated with respect to organic carbon and total sulfur contents ash yields maceral composition organic geochemistry and stable carbon isotope ratios the lignites from the two sampled profiles differ in sulfur contents and petrography based facies indicators gelification index gi tissue preservation index tpi the results point to drier and more acidic conditions in the part of the mire sampled at drill site lukasberg whereas the lignites from kalletsberg formed under near neutral conditions due to a raised ground water table the different depositional environments are supported by the paleogeographic positions of the boreholes borehole lukasberg is located within a paleo valley whereas borehole kalletsberg is located at the deeper part of a basin situated south and southwest of the hausruck area environmental changes with time within the mire are confirmed by the molecular composition of the soluble organic matter som differences in pristane phytane ratio isomerisation of hopanes at position 17 concentrations of hopanes and in the ratio of hopanes to hop 17 21 enes are related to the extent of gelification of plant tissue sulfur content and ph values caused by differences in ground water table the variable contents of individual terpenoid hydrocarbons derived from land plants indicate that angiosperms and conifers contribute to peat formation in the hausruck district in variable proportions overall angiosperm biomarkers slightly predominate the tissue preservation index tpi within the kalletsberg profile is probably governed by the proportion of decay resistant conifers as indicated by the correlation between tpi and biomarker composition of the coals correlations between 13 c values of the lignites between 24 9 and 27 4 and their non hopanoid terpenoid composition indicate the major influence of changes in peat forming vegetation on the carbon isotopic composition of the coals in the hausruck district carbon isotope data of macrofossils are consistent with their taxonomical classification as conifers 13 c between 22 7 and 25 1 and angiosperms 13 c between 25 5 and 26 6 respectively the 13 c data of the extracted cellulose reveal clear differences between fossil wood from gymnosperms average 13 c 21 0 and angiosperms mean 13 c 23 4

coal characteristics and biomarker investigations of dombayova coals of late miocene pliocene age afyonkarahisar turkey abstract in dombayova graben dinar afyonkarahisar western turkey a 203 m thick coal bearing zone of late miocene to pliocene age was recently drilled the zone hosts several coal beds with a total thickness of 46 m coal samples from the dombayova field were studied by means of standard proximate ultimate petrological analyses micro ftir spectroscopy and rock eval pyrolysis and organic geochemical analyses coal proximate analyses and the presence of carbonate minerals and fossil shell fragments point to alkaline surface waters of changing ph values due to fluctuations of the water level in the paleomire and or ca rich water influx low sulfur contents argue for sulfate limitation of bacterial sulfate reduction petrographic observations reveal that the coal is dominantly composed of weakly altered wood fragments and roots the mean random reflectance values of ulminite 0 33 ro indicate lignite rank of the coal the micro ftir data of macerals of huminite group indicate higher contributions of aliphatic hydrogen in textinite compared to more aromatic levigelinite the semi quantitative differences in the ratios of selected functional groups suggest that aromaticity and the extent of oxidation are higher in levigelinite aliphatic chains are longest in textinite and ulminite and shortest in texto ulminite and levigelinite we interpret this difference to point to a different origin of levigelinite probably from colloidal humic solutions that were gelified during diagenesis the concentrations of n alkanes and their distribution patterns provide evidence for higher terrestrial plants as the dominant source of organic matter decreasing pristane phytane ratios with depth are interpreted to reflect more reducing conditions during peat formation due to higher ground water level the absence of diasterenes is most probably caused by low clay mineral contents and is consistent with the presence of alkaline waters in the paleomire the presence of terpenoid hydrocarbons in the lignite indicates a major contribution of angiosperms to peat formation the positive relationship between the concentrations of perylene and lupane type triterpenoids suggests an increasing abundances of wood degrading fungi in the peat forming vegetation characterized by a high density of betulaceae

biomarkers and geochemical indicators of holocene environmental changes in coastal lake sarbsko poland organic rich samples from the holocene sedimentary sequence of lake sarbsko were investigated to reconstruct variations in the aquatic system in response to environmental change the aims were to i identify organic matter om sources ii examine changes in soluble om composition in relation to fluctuations in limnological conditions and iii validate the sensitivity of organic geochemical indicators in tracing environmental changes diatom frustules are abundant in all samples alginite macerals and terrigenous organic matter further contribute to the sedimentary om organic petrography total organic carbon toc n ratio values and high content of biogenic silica sio2 biogenic argue for a predominant algal source of om in contrast the n alkane distributions high relative abundance of c29 steroid hydrocarbons and high content of detrital quartz in the sediments provide evidence for the input of terrigenous material as a major om source within the basin the terpenoid biomarker composition indicates a contribution from conifers and angiosperms from the diterpenoids in the samples a contribution from species of the coniferales family pinaceae is concluded toc s and mg ca values as well as steroid hopanoid concentration ratios reflect enhanced water salinity in this coastal lake due to ingression of brackish water from the baltic sea during the atlantic and sub atlantic periods as indicated by the positive relationship between d 13 c of toc and mg ca d 13 c values are influenced by changing contribution of marine vs freshwater phytoplankton additional isotopic heterogeneity in d 13 c may result from differences in terrigenous om supply vs autochthonous om production in the lake the isotopic composition of calcites supports the establishment of freshwater conditions in the lake during the sub boreal period pristane phytane and fe mn ratios are interpreted to reflect differences in the redox conditions oxygenation of bottom waters was temporarily variable with highest levels of oxygen availability during the sub boreal freshwater lake high contents of hopanoid hydrocarbons argue for enhanced microbial activity in the water column and sediment the occurrence of 2b methyl hopanes is related to the presence of cyanobacteria or methylotrophic bacteria

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

diphytanyl glycerol ether distributions in sediments of the orca basin abstract archaebacterially produced diphytanyl glycerol ether dpge was examined in core sediments from the orca basin an anoxic hypersaline basin in the northwestern gulf of mexico to observe its spatial variability and potential origin a differential extraction protocol was employed to quantify the isopranyl glycerol ethers associated with unbound intermediate bound and kerogen bound lipid fractions archaebacterial lipids were evident at all depths for the unbound and intermediate bound fractions concentrations of dpge ranged from 0 51 to 2 91 g g dry sediment at the surface and showed secondary maxima deeper in basin sediments intermediate bound dpge concentrations exhibited an inverse relationship to unbound dpge concentrations kerogen bound dpge concentrations were normally below detection limits earlier studies describing the general homogeneity of lipid components within the overlying brine and at the brine seawater interface suggest that the large scale sedimentary dpge variations observed in this study result from spatial and temporal variations in in situ production by methanogenic or extremely halophilic archaebacteria

rapid sulfurisation of highly branched isoprenoid hbi alkenes in sulfidic holocene sediments from ellis fjord antarctica samples of particulate organic matter from the water column and anoxic holocene sediment layers from the small meromictic basin smb in ellis fjord eastern antarctica were analyzed to study the early incorporation of reduced inorganic sulfur species into highly branched isoprenoid hbi alkenes hbis were not detected in the water column samples taken during austral winter whereas compounds containing the c25 hbi skeleton were abundant in all analyzed holocene sediment layers the structure of the c25 2 hbi alkene and its enriched stable carbon isotopic composition suggest that it is produced by a diatom or diatoms probably belonging to the navicula genus in the sea ice which covers the area most of the year within just 500 years of deposition all of the hbi alkene was sulfurised a mixture of products was formed including components tentatively identified as a c25 hbi thiane and three s containing dimers composed of two c25 1 hbi skeletons linked together by a sulfide bond most was however converted to polar s containing compounds the reaction rate for sulfurisation of the c25 2 hbi alkene is the highest observed so far in natural systems sterols and other lipids known to be prone to sulfurisation were not sulfurised the reason for this is unclear

depositional environment of the lower cretaceous muling formation of the laoheishan basin ne china implications from geochemical and petrological analyses abstract the laoheishan basin located in northeastern china is filled with non marine coal and oil shale oil prone mudstone sediments of the lower cretaceous muling formation based on petrological mineralogical and geochemical methods the depositional environment during organic matter om accumulation is investigated for the first time the coal is subbituminous in rank petrological and bulk geochemical data indicate sapropelic coal deposited in low lying mire under freshwater conditions high pristane phytane ratios provide evidence for a land plant origin of om and oxic conditions during deposition a neutral to slightly alkaline ph is reflected by the presence of carbonate high liptinite contents and terpenoid biomarker composition indicate high amounts of resinous om during oil shale deposition a raised water table was favorable for om preservation under oxic to dysoxic conditions the oil shales in the lower unit of the succession not associated with coal are characterized by high hydrogen index and resinite contents interpreted to reflect deposition at elevated water depths in contrast to the findings of previous studies on oil shales in china indicating its origin from algal om a predominance of terrigenous om rich in waxy and resinous lipids is implied from biomarker and maceral composition the lower cretaceous oil shale and coal in the laoheishan basin contain high amounts of land plant derived terpenoid biomarkers derived from coniferales e g pinaceae cupressaceae taxodiaceae araucariaceae podocarpaceae and ferns the results are in agreement with palynological data the data highlight the potential of resinous and waxy om to form excellent hydrocarbon source rocks

diagenesis and distribution of acyclic isoprenoid hydrocarbons in late miocene to pliocene marine siliceous rocks from horonobe hokkaido japan abstract a sequence of late miocene to pliocene siliceous mudstones from boreholes hdb 3 and hdb 4 from horonobe hokkaido japan is homogeneous and useful for the study of diagenetic degradation and transformation of sedimentary organic matter using these siliceous mudstones the diagenetic change in acyclic isoprenoid hydrocarbons was investigated the palaeotemperatures of the samples were estimated to be in the range 30 60 c on the basis of the silica mineral transformation and the present day geothermal gradient in the region the relative abundances of pristane to pristenes and phytane to phytenes increase drastically with depth the remarkable changes in pristane pristene and phytane phytene occur in a temperature range of about 35 50 c the relative abundances could be potential parameters for palaeotemperature analysis of immature sedimentary rocks remarkable increases in pristane and phytane concentration with maturity show that in addition to extractable free pristenes and phytenes bound acyclic isoprenoids are the major source of pristane and phytane pristane phytane and pristenes phytenes are nearly constant through the entire boreholes showing that the relative abundance of the precursor c 19 c 20 acyclic isoprenoids was determined at the time of deposition and or in the early stage of diagenesis pristene phytene as well as pristane phytane could be useful parameters for assessing palaeodepositional environment

influence of floral assemblage facies and diagenesis on petrography and organic geochemistry of the eocene bourgas coal and the miocene maritza east lignite bulgaria abstract numerous differences in the petrography and organic geochemistry of two tertiary low rank coal deposits of bulgaria formed within comparable depositional environments are outlined different floral assemblages are indicated as the main sources of organic matter for the eocene bourgas sub bituminous coals a warm climate plant community dominated by angiosperms is reflected in the biomarker composition whereas a coniferous flora was the main source of the resinous organic matter of the miocene maritza east lignite the results are in agreement with palaeobotanical data these differences in the peat forming vegetation of the paleogene compared to the neogene of bulgaria are attributed to decreasing temperature during the tertiary the abundance of resinous compounds relative to lipids from plant waxes long chain n alkanes as well as the preservation of plant tissue are mainly controlled by gymnosperm angiosperm ratios pristane phytane and diasterenes sterenes ratios reflect variations in redox conditions and the ph of the depositional environments caused by eustatic sea level changes freshwater inflow or varying ground water table changing eh and ph values are associated with differences in microbial activity controlling the extent of gelification of plant tissue bacteria most probably contributed to the aromatisation of triterpenoids in the mire enhanced thermal maturation of organic matter during diagenesis is reflected in higher contents of n alkanes and the presence of alkyl naphthalenes in the bourgas coals alkyl naphthalenes are thought to have been formed from pentacyclic triterpenoids rather than from resinous compounds

the evolution of ace lake antarctica determined from sedimentary diatom assemblages abstract the sediments in ace lake in the vestfold hills east antarctica contain a continuous sequence of diatom frustules that record the lake s history since its formation during the retreat of continental ice more than 9200 years ago frustules from six indicator groups pinnularia microstauron nitzschia cylindrus nitzschia curta eucampia antarctica a freshwater stauroneis species and several centric species in a sediment core were used to determine the sequence of the lake s evolution the history of the lake falls into five stages ace lake began as a marine inlet influenced by dynamic mixing of ocean and meltwater inputs as the ice sheet retreated isostatic uplift isolated the lake allowing it to be flushed by meltwater input from the retreating ice sheet over the course of 800 years 9200 8400 14c yr b p the lake became meromictic supporting a freshwater diatom assemblage approximately 6700 years ago coinciding with antarctic sea level maxima diatom assemblages indicate that seawater flooded over the sill into ace lake disturbing the freshwater meromixis the sediments in this period were laminated and contained elemental sulphur suggesting that the marine input was limited in extent and energy approximately 5500 years ago this marine input ceased and the lake again became a meromictic basin which stabilised over 1700 years to become the lake that it is today and has been with little change for about the past 4000 years

facies evolution and stratigraphic correlation in the early oligocene tard clay of hungary as revealed by maceral biomarker and stable isotope composition abstract hydrocarbon source rocks i e tard clay formation containing type ii organic matter were deposited in the hungarian paleogene basin during lower oligocene a major contribution of aquatic organisms green algae dinoflagellates chrysophyte algae and minor inputs from macrophytes and land plants to organic matter accumulation is indicated by n alkane distribution patterns composition of steroids and 13c of hydrocarbon biomarkers microbial communities included heterotrophic bacteria cyanobacteria chemoautotrophic bacteria as well as green sulphur bacteria the presence of methanotrophic bacteria is indicated by 13c depleted hop 17 21 ene higher inputs of terrestrial organic matter occurred during deposition of the lower and uppermost units of the tard clay formation the terpenoid hydrocarbon composition argues for angiosperm dominated vegetation in the area of the hungarian paleogene basin diterpenoid hydrocarbons derived from the resins of conifers are about 2 3 enriched in 13c compared to the angiosperm biomarkers environmental conditions changed from marine to brackish accompanied by oxygen depletion in the lower parts of the water column organic carbon accumulation during this period was a consequence of stagnant bottom water conditions in the hungarian paleogene basin due to salinity stratification this is indicated by low pristane phytane ratios varying from 0 27 to 1 44 enhanced ratios of dimethylated versus trimethylated mttcs 0 14 0 59 and the presence of aryl isoprenoids from 0 4 to 14 1 g g toc a major marine incursion is evidenced by stable isotope ratios of organic matter and carbonates in the uppermost member of the tard clay a transition from brackish towards normal marine conditions is proposed up to 3 anoxic cycles are recognized in the drill core sections separated by minima in pristane phytane ratios and maxima in the depth trends of di tri methylated mttcs and aryl isoprenoid concentrations in combination with the position of maxima of 13c of carbonate and organic matter and an abrupt decrease in perylene concentrations the cycles can be used for intra formational correlation of the tard clay