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The scope of this study was to develop robust lithofacies proxies which are less affected by other geochemical processes such as maturity and biodegradation. Here, crude oils derived from carbonate and siliciclastic source rocks from different petroleum settings were investigated using Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), thereby providing information on the role of depositional environment in controlling the chemical composition of hydrocarbons. The carbonate oils belong to the Western Canada Sedimentary Basin (WCSB) and the siliciclastic oils were mainly collected from the Austrian parts of the Molasse Basin and the Vienna Basin, Austria. The variations in chemical composition, aromaticity as well as alkylation degree of the main compound classes in both oil types are discussed in detail using data from FTICR-MS in two different ionization modes: electrospray ionization in negative ion mode (ESI–N) and atmospheric pressure photoionization in positive ion mode (APPI–P). The results obtained from both ionization modes indicate that the chemical compound distributions of acidic constituents such as oxygen-only components (the O1 to O4 classes) and the N1S1 class, as well as sulfur and hydrocarbon species in oils from carbonates are clearly different from those generated by siliciclastic rocks. Most likely, the observed differences are attributed to depositional environments of the respective source rocks as the impacts of other processes such as thermal maturity and biodegradation, were mitigated by selection of non-biodegraded oils that display comparable maturation levels. The calculated vitrinite reflectance (%Rc) in most of the selected oils range between 0.5 and 0.8. The observed differences in chemical composition of oils from carbonates and siliciclastics lead to suggested novel source-sensitive proxies based on the DBE distribution of the S1 and HC species (from APPI–P) and the O1 and N1S1 classes (from ESI–N). The former proxy is the ratio of the S1 class DBE 9 group (radical ions; likely sum of alkylated dibenzothiophenes) relative to the HC class DBE 10 group (radical ions; likely sum of alkylated phenanthrenes). It appears that this proxy is mirroring the “DBT/P ratio” obtained from GC–MS data over a much broader range of molecular masses up to approximately 1000 Da. The other proxy is based on the observed differences between the O1 class DBE 4 group and the N1S1 class DBE 14 group. Whereas oils derived from the siliciclastic source rocks show higher concentrations of the O1 class, oils originated from the carbonate source units are enriched in the N1S1 species. Finally, published FTICR-MS data (APPI–P) from both oil source types with varying levels of maturation and biodegradation are included, in order to verify the robustness of the proposed proxies.

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.

The Maikop Formation, deposited in eastern Azerbaijan during Oligocene and Early Miocene, represents a prolific source unit for the oils found within the southern Gobustan area and the Kura Depression. Based on biomarker characteristics, the oils are believed to have originated from a clastic source rock deposited in an anoxic to suboxic, transitional marine environment with low to moderate input of terrigenous organic matter. However, due to the thermal immaturity of accessible Maikop rocks, oil–source rock correlation based on biomarker fingerprints is hampered. The results from a sedimentary succession sampled in the Shemakha–Gobustan area near the village of Lahich revealed the presence of marginally mature (Rr = 0.6–0.7%) Maikop rocks. Based on lithology, geochemical data and paleontological analyses, the sampled section contains Upper Eocene and Lower Oligocene sediments. Palynological analyses of dinoflagellate cysts indicate an early Rupelian to early Chattian (Oligocene) age for the upper part of the investigated Maikop succession. However, the stratigraphic position of the middle and lower part of the succession remains unclear. Maceral composition, as well as biomarker and stable isotope (C, N) data indicate a major contribution of aquatic organisms and variable inputs from macrophytes and land plants to organic matter deposition during the Oligocene. Microbial communities most probably included heterotrophic bacteria and cyanobacteria, as well as green sulfur bacteria. Higher inputs of terrigenous organic matter occurred during deposition of the lower part of the succession. Increased remineralisation of organic matter in the water column is suggested to result in low TOC and hydrocarbon contents, as well as 15N enriched total nitrogen of the Eocene to earliest Oligocene sediments. Organic carbon accumulation during the Oligocene occurred in a stratified, episodically euxinic environment. This is indicated by low TOC/S ratios and higher contents of aryl isoprenoids in several samples from the upper units. A moderate to good oil–source rock correlation with oils from the Kura Depression is indicated by sterane and triterpane fingerprints as well as carbon isotopic composition of hydrocarbon fractions.

The Maikop Formation, deposited in eastern Azerbaijan during Oligocene and Early Miocene times, contains prolific source rocks with primarily Type II organic matter. Paleontological analyses of dinoflagellate cysts revealed a Lower to Upper Oligocene age for the investigated succession near Angeharan. A major contribution of aquatic organisms (diatoms, 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 δ13C of hydrocarbon biomarkers. Microbial communities included heterotrophic bacteria, cyanobacteria, chemoautotrophic bacteria, as well as green sulfur bacteria. Higher inputs of terrigenous organic matter occurred during deposition of the Upper Oligocene units of the Maikop Formation from Angeharan mountains. The terpenoid hydrocarbon composition argues for angiosperm dominated vegetation in the Shamakhy–Gobustan area. High primary bioproductivity resulted in a stratified water column and the accumulation of organic matter rich sediments in the Lower Oligocene units of the Maikop Formation. Organic carbon accumulation during this period occurred in a permanently (salinity-) stratified, mesohaline environment with free H2S in the water column. This is indicated by low pristane/phytane ratios of all sediments (varying from 0.37–0.69), lower methylated-(trimethyltridecyl)chromans ratio in the lower units and their higher contents of aryl isoprenoids and highly branched isoprenoid thiophenes. Subsequently, the depositional environment changed to normal marine conditions with oxygen deficient bottom water. The retreat of the chemocline towards the sediment–water interface and enhanced oxic respiration of OM during deposition of the Upper Oligocene Maikop sediments is proposed. Parallel depth trends in δ13C of total OM, n-alkanes, isoprenoids and steranes argue for changes in the regional carbon cycle, associated with the changing environmental conditions. Increased remineralisation of OM in a more oxygenated water column is suggested to result in low TOC and hydrocarbon contents, as well as 15N enriched total nitrogen of the Upper Oligocene units.

Excellent hydrocarbon source rocks (oil shales), containing Type I organic matter (OM), were deposited in the continental Songliao rift basin during the Late Cretaceous. A major contribution of aquatic organisms (dinoflagellates, green algae, botryococcus) and minor input from macrophytes and land plants to OM accumulation is indicated by n -alkane distribution, steroid composition and δ 13 C values of individual biomarkers. Microbial communities included heterotrophic bacteria, cyanobacteria and chemoautotrophic bacteria, as well as purple and green sulfur bacteria. The presence of methanotrophic bacteria is indicated by 13 C-depleted methyl hopane. The sediments were deposited in a eutrophic, alkaline palaeolake. Highly reducing (saline) bottom water conditions and a stratified water column existed during OM accumulation of the Qingshankou Formation and Member 1 of the Nenjiang Formation. This is indicated by low pristane/phytane, gammacerane index and MTTC ratios, and the presence of β-carotane and aryl isoprenoids. However, an abrupt change in environmental conditions during deposition of Member 2 of the Nenjiang Formation is indicated by significant changes in salinity and redox-sensitive biomarker ratios. A freshwater environment and suboxic conditions in the deep water prevailed during this period. Higher input of terrigenous OM occurred during deposition of the upper Nenjiang Formation. Good oil-to-source rock correlation was obtained using biomarker fingerprints of oil-stained sandstone from the Quantou Formation and oil shales from the Qingshankou Formation. Based on the extent of isomerisation of C 31 hopanes, the oil was most probably derived from oil shales of the Qingshankou Formation in deeper parts of the basin.

The type of organic matter (OM) in European Carboniferous and Permian swamp and lake sediments from the Carboniferous and Permian was determined using organic petrography, Rock–Eval data and biomarker distributions. Coals deposited in swamps contain humic OM formed under oxic conditions. Boghead coals and black shales deposited in lakes contain a mixture of algal and humic OM formed under reducing conditions. Diterpanes and previous palaeobotanic studies constrain the species of plants living near the lacustrine shore or in the swamp during deposition, allowing the palaeoclimate to be inferred. During the Carboniferous, the climate was not always tropical wet, as some periods of dryness are evident from the sedimentology, palaeobotany and organic geochemistry. During the Permian, the climate was not always tropical dry as some periods of wetness associated with the monsoons are recorded (Roscher, M., Schneider, J.W., 2006. Permocarboniferous climate: Early Pennsylvanian to Late Permian climate development of central Europe in a regional and global context. In: Lucas, S.G., Cassini, G., Schneider, J.W. (Eds.), Non-Marine Permian Chronology and Correlation, vol. 265. The Geological Society of London, pp. 95–136). The appearance of xerophyte plants from the Stephanian was also recorded by way of aromatic hydrocarbons, retene for gymnosperms and arborane/fernane for cordaites and probably seed ferns. Cycles of wetness and dryness for Europe during the Carboniferous and Permian are proposed on the basis of comparison of aliphatic and aromatic hydrocarbons. δD values provided information on the palaeotemperature of the air in the swamps and water in lakes, as well as palaeoclimate. Values of ca. −100‰ seen in the Carboniferous coals and Permian limnic deposits are indicative of a tropical climate, in contrast to a glacial or temperate climate, where the values are ca. −200‰. The value for Carboniferous coals could result from high evapotranspiration of plants living under a wet tropical climate vs. a temperate climate. During the Early Permian the climate was dry tropical. For such samples, the δD values for the n-alkanes derived from lacustrine algae were depleted in D relative to the values for the n-alkanes derived from terrestrial higher plants, attributed to the higher evapotranspiration on land than evaporation from the lake. Alternatively, the xerophytic plants that drifted into the lake via a river could have grown during a dry phase and the autochthonous algae bloomed during a wet phase.

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 δ 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 δ 13 C data (mean δ 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.

The mine soils and sediments in the Lusatian open-cast lignite mining district (Germany) contain substantial amounts of lignite in addition to recent organic matter derived from plant litter. Knowledge of organic matter (OM) types and their transformation in mine soils and sediments is essential for the evaluation of ecosystem functioning in this region. The aim of the study was to use the isotopic signature of OM to: (1) determine lignite C contribution and (2) elucidate the contribution of OM derived from plant litter to three physical fractions in order to deduce its degree of degradation in three contrasting environments. We used stable and radioactive C isotopes to quantify the contribution of lignite C and to characterize humification processes occurring under contrasting vegetation and redox conditions. The upper mineral soil/sediment, the litter layer and the vegetation of three plots were sampled along a transect covering a forest soil, a partially submerged sediment at the land–water interface characterized by fluctuating water levels, and a constantly submerged sediment. The soil/sediment samples were fractionated into a macro (>250 lm), a humus (material separated by flotation) and a sand (mainly mineral material) fraction to follow the transformation processes of plant and lignite. Radiocarbon analysis of the humus fraction showed a lignite C contribution ranging from 20% to 80% of total organic carbon (OC). The 14 C activity was correlated with the d 13 C value (r 2 = 0.95). Even if not precise, in this case the correlation was used to get an idea about the lignite contribution in coal mining-impacted freshwater sediment and soil. The 13 C data showed that lignite C contribution increases with depth in every fraction of the forest and partially submerged plots. At the submerged plot, the humus and macro fraction were almost free of lignite C, suggesting high amounts of fresh plant material at this plot. This was confirmed by the highest contribution (up to 40%) of the macro fraction, which is mainly composed of fresh plant material, to the total OC content in this plot. In the first 5 cm of all plots, most OC was found in the humus fraction. Combined elemental and isotopic analysis of the three physical fractions indicated that high amounts of humified OM were present in the constantly submerged sediment, whereas most intensive degradation of OM was occurring in the partially submerged sediment at the land–water interface. Here, d 13 C values show that lignite C contributes to

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 (δ13C=−25.3 to −27.0‰) is proposed. Carbon cycling during biogeochemical decomposition of plant tissue by bacteria is assumed to affect the δ13C 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 (δ13C=−24.5‰) and the extracted cellulose (δ13C=−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 δ13C values of wood and extracted cellulose are affected to a minor extent by microbial activity.

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 (δ13C=-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 δ13C 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 δ13C 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 δ13C values of coal. δ13C values of wood and extracted cellulose are affected only to a minor extent.

Up to 16 m thick coal seams formed in Miocene pull-apart basins within the Eastern Alps in low-lying and raised mires. Despite similar rank (sub-bituminous stage), coal quality differs significantly. Coals from low-lying mires (e.g. Fohnsdorf) are characterized by significantly higher ash yields and sulfur contents than coals from raised mires (e.g. Leoben). Organic geochemical and carbon isotope investigations were performed to assess the differences in facies. The Fohnsdorf coals are characterized by higher yields of soluble organic matter (SOM), slightly higher proportions of hydrocarbons in the SOM, generally lower pristane / phytane ratios, and the occurrence of high Corg-normalized n-alkane concentrations. Only n-alkane patterns in the Leoben samples show a marked odd over even predominance. These differences are indicative of a more intensive, dys- to anaerobic biochemical degradation of plant material within the Fohnsdorf mire. Terpenoid biomarkers characteristic of conifers and angiosperms were detected in the Leoben coals, whereas the latter are missing in the Fohnsdorf samples. In the Leoben coals higher saturated to aromatic diterpenoid ratios were detected than in the Fohnsdorf coals. Because of similar rank, enhanced aromatisation in the Fohnsdorf basin is probably related to microbial activity. Despite this, the Fohnsdorf coals are characterized by lower hopane concentrations. The results imply that the aromatisation of terpenoid biomarkers is governed by the activity of anaerobic rather than aerobic bacteria. An overall negative correlation between δ13C of organic matter and the degree of aromatisation of diterpenoid biomarkers is observed. It is suggested that the carbon isotopic composition results from different extents of microbial degradation of the biomass. The Fohnsdorf coals are rich in sulfur. High contents of coalbed methane were encountered during mining, suggesting high activities of anaerobic bacteria in a nearly neutral, sulfate-bearing (brackish) environment of the low-lying mire and methanogenesis during or after coalification. Sulfate-reduction and methanogenesis are known to increase δ13C values of residual organic matter.

9 pages, 5 figures, 3 tables, 37 references., The objective of this study was to assess high energy UV photo-oxidation, 13C CP/MAS NMR spectroscopy and 14C activity measurements for their suitability in differentiating carbon derived from plant material and that derived from lignite. The conceptual approach included analysis of bulk soil samples and physical fractions of lignite-rich mine soils. Additionally, the, The authors would like to thank the Deutsche Forschungsgemeinschaft for financial support.

Organic geochemical data of Lower Cretaceous shallow water sediments from two sites (865 and 866) drilled during ODP leg 143 are presented. The organic matter is mainly terrestrial at the bottom of the sedimentary column at site 865, whereas algal and/or bacterial organic matter is dominant at site 866. This is the first evidence of shallow water deposition of organic matter during the Early Cretaceous in the Northwestern Pacific. The lower Aptian organic carbon-rich layers from the shallow water sediments of site 866 are geochemically similar to coeval mid-water sediments of site 463.

Bituminous marls occur at the base of the late Cretaceous Kainach Gosau Basin, Eastern Alps. They interfinger with local coaly layers, and are overlain by a turbiditic sequence. Forty outcrop samples with different lithologies were studied by Rock-Eval pyrolysis. Seven bituminous marls, one coaly sample, two siltstones from the turbiditic sequence and solid bitumen from the Paleozoic basement have been characterized in detail by organic geochemical and petrographic techniques. The organic matter from bituminous marls can be subdivided into allochthonous, terrigenous material (mainly recycled vitrinite), which is present in all samples in similar amounts, and autochthonous hydrogen-rich organic matter (alginite, liptodetrinite), which is most probably of lacustrine origin. Organic richness varies from 0.4 to 2.3% TOC. The amount of the autochthonous organic matter is controlled primarily by different oxygen concentrations. Sedimentological (lack of bioturbation) and geochemical data (e.g., pristane/phytane ratios, homohopane indices, C∗ 30 C 29 Ts ratios, distribution of phenol and alkylphenols in the pyrolyzate) suggest that the water column above the sediment surface was suboxic to dysoxic, but probably not anoxic. High energy events were responsible for short periods with enriched oxygen in the water column. The organic matter in the resulting sediments is of a residual type. Drift wood was transported from the nearby shore into the lake. Paleontological evidence proves a temporary marine influence. Vitrinite reflectance and Tmax indicate maturation levels ranging from the beginning to the peak stage of oil generation. Despite the fact that some hydrocarbons have already been generated, HI values of kerogens of bituminous marls reach 605 mg HC/g TOC. Most analysed bituminous marls produce a high wax paraffinic oil during maturation and are good sources for oil. Pyrolysis-gas chromatography and biomarker data indicate that changing wax contents of oils generated from bituminous marls might be a function of different oxygen concentrations in the water column. Coaly samples have a very good gas potential.