biomarker distributions in australian oils predominantly derived from terrigenous source material oils found in many australian sedimentary basins contain a relatively high input of terrigenous organic source material a study of a large number of these oils has permitted a number of biomarker distributions to be determined that appear to be characteristic for oils derived from terrigenous source material these features include the presence of sesquiterpanes absence of tricyclic terpanes relatively high concentrations of a c24 tetracyclic terpane predominance of c29 steranes presence of two unidentified c27 and c30 terpanes and virtual absence of 18 h oleanane the latter observation is significant since it appears that 18 h oleanane appears only in oils of tertiary age derived from terrigenous source material an attempt has also been made to compare the results for the australian oils with published results for oils derived from terrigenous source material in other parts of the world the number of reports in the literature for these oils is fairly limited but it appears that some of the observations for the australian oils can be extended to them this study is an initial attempt to devise a classification scheme that can be used to determine the origin of an oil unambiguously from biomarker parameters in order for this approach to be successful a relatively large number of biomarker parameters need to be assigned as characteristic of a particular type of source material

an integrated analytical approach for determining the origin of solid bitumens in the mcarthur basin northern australia abstract an integrated analytical approach using petrological geochemical and isotopic techniques has been used to determine the origin of solid bitumens in the middle proterozoic roper group mcarthur basin northern australia sandstone and dolerite samples which in hand specimen contain dark material believed to be solid bitumens were examined from six wells under ultraviolet illumination non fluorescent solid bitumens can be distinguished from two generations of crude oil one of lower maturity orange fluorescence the other of higher maturity white fluorescence other petrographic observations indicate that the precursor hydrocarbons to the solid bitumens and the subsequent charges of crude oil postdate all diagenetic clay and quartz cementation geochemical analyses indicate that many of the sandstones contain both an aliphatic rich oil and solid bitumen mixed in varying proportions thus corroborating the petrological results on the basis of n alkane distributions the oil appears to have two 3ubtly different source inputs one of which is typified by a greater proportion of high molecular weight n alkanes which have a slight even carbon number predominance and an isotopically lighter aliphatic hydrocarbon fraction one sandstone sample contains solid bitumen in a fracture which is characterized by a high abundance of asphaltenes polar compounds and sulphur and may have formed by deasphalting of a precursor oil the solid bitumens recovered from fractures in dolerite sills were formed by thermal processes which in one sample resulted in an unusual series of ketone isomers however most solid bitumens particularly where present in the coarser sandstones are related to the generation of secondary porosity the large proportion of unresolved complex mixture the lack of n alkanes and the isotopically heavier aliphatic hydrocarbon fractions of samples containing predominantly solid bitumens indicate that bitumen formation occurred mainly by biodegradation of a precursor oil

geochemical characterisation of middle devonian oils in nw alberta canada possible source and maturity effect on pyrrolic nitrogen compounds abstract molecular geochemical compositions of a suite of middle devonian sourced and reservoired oils from the rainbow zama shekilie sub basins in n w alberta canada reveal the presence of at least two oil families in the study area the distribution of each oil family is geographically restricted to a single sub basin consistent with the oils being sourced locally within a series of closed generation migration trapping systems the diversity in the biomarker distributions of the oils indicates the wide range of depositional environments and source materials existing in each sub basin rather than mixing of end member oils across different sub basins clear maturity differences are observed between the oils from the rainbow and zama subbasins pre cretaceous thermal anomalies along the reactivated regional precambrian basement faults are proposed as one of the major causes for the relatively high maturity levels for the middle devonian source rocks in the study area we infer that depositional environment and thermal maturity have had a strong impact on the geochemical characteristics of the saturated and aromatic hydrocarbons in the rainbow shekilie zama oils but may not influence the pyrrolic nitrogen compounds to a significant extent however recognition of possible source and maturity effects on pyrrolic nitrogen compounds in other studies suggests that these factors should be considered before the pyrrolic nitrogen compounds are used to characterize petroleum migration

trace element geochemistry of crude oils and condensates from south african basins abstract crude oil and condensates samples from bredasdorp and orange basins south africa were analyzed for trace elements using inductively coupled plasma optical emission spectrometry the oil and condensate samples were analyzed to classify the oils into family and to determine the origin of the oils and depositional environment of organic matter that yielded the oils using trace elements the concentrations of the elements co cr cu fe mn ni and v determined ranged from 0 10 to 7364 7 ppb iron is the most abundant element in the samples while cobalt is least abundant both concentrations and ratios of nickel and vanadium showed two main families of oils oils of marine origin and oils of terrestrial origin oil samples from the orange basin are mainly of marine source and their organic matter were deposited under anoxic conditions most of the oil samples from the bredasdorp basin are of marine origin with a few samples having terrestrial origin cluster analysis also classified the oil and condensate samples from the two basins into two main families of marine and terrestrial sources

late quaternary hydrothermal sedimentation adjacent to the central lau spreading center the partition geochemistry of 10 sediment cores collected adjacent to the southward propagating central lau spreading center clsc has been studied the hydrothermal oxide component in these sediments is mainly formed of mn oxides containing other hydrothermally associated elements e g fe zn cu mo and pb the mn oxides represent distal plume fall out derived from hydrothermal vents hydrothermal mn accumulation rates are between 2 6 and 74 4 mg cm 2 ka 1 during the 0 30 ka period and between 2 1 and 12 8 mg cm 2 ka 1 during the 30 120 ka period recent 30 ka hydrothermal input to the sediments adjacent to the clsc has been more variable than in the older sediments from the area this may be attributed to localised hydrothermal activity occurring behind the propagator and possibly to magma chamber development periods of enhanced hydrothermal input from the clsc at ca 30 ka and 175 ka appear to be contemporaneous along the clsc however an enrichment in mn at ca 112 ka probably represents distal hydrothermal plume fall out from increased activity on the valu fa ridge in the southern lau basin hydrothermal mn input derived from the clsc is below that from the vfr

geochemical application of tricyclic and tetracyclic terpanes biomarkers in crude oils of nw china composition and distribution of tricyclic terpanes tetracyclic terpanes and hopane in crude oils from tarim turpan ordos and qaidam basins nw china were investigated and some new source dependent parameters were developed and evaluated c 19 and c 20 tricyclic terpanes are more abundant in terrigenous oils with c 24 tetracyclic terpane dominant relatively higher carbon number tricyclic terpanes especially c 23 tricyclic terpane are often the dominant homologues in crude oils from saline lacustrine and marine sources on the whole the relative content of c 23 tricyclic terpane of crude oils follow the order of saline lacustrine oils marine oils freshwater lacustrine oils terrigenous oils for c19 23 tricyclic terpane some new parameters based on the tricyclic hopane and tetracyclic tricyclic terpane as well as tetracyclic hopane ratios could be used to distinguish the oils and source rocks with similar maturity deposited in different sedimentary environments c 2015 elsevier ltd all rights reserved

geochemical constraints on models for secondary petroleum migration along the upper devonian rimbey meadowbrook reef trend in central alberta canada abstract the upper devonian rimbey meadowbrook reef trend of central alberta canada is one of the classical examples that was originally used to support gussow s model of differential hydrocarbon entrapment however the clear discrepancies existing between the ideal hydrocarbon distribution predicted by this model and the one actually observed led to several alternative geological models most of which have not been constrained by organic geochemical data the present study uses a wide range of bulk and molecular parameters to determine the oil source characteristics and thermal maturity along the reef trend the concentrations and isomeric distributions of alkylcarbazoles and non alkylated benzocarbazoles in oils are employed to study petroleum migration pathways and to constrain the existing secondary petroleum migration models the data indicates that gussow s principle is generally applicable as the oils in the up dip direction generally have longer implied migration distances although this is not always the case other factors not recognized previously such as the presence of two subfamilies of the duvernay formation sourced oils may also have contributed significantly to the discrepancies in the oil and gas distributions between the model predictions and the actual observational data

significance of coniferous rain forests and related organic matter in generating commercial quantities of oil gippsland basin australia contrary to the conventional belief that humic coal generates primarily gas 3 billion bbl of recoverable oil has been discovered in the humic coaly succession of the fluviodeltaic latrobe group upper cretaceous tertiary that serves as both the reservoir and the source for hydrocarbons in the offshore gippsland basin of southeastern australia evidence for generation of liquid hydrocarbons from the coaly succession includes 1 similarity of n alkane distribution in the oil and in the coal extracts 2 high wax content of oil up to 27 by weight 3 high ratio of pristane phytane in oil 5 6 and 4 dominance of c29 steranes in the oil in the gippsland basin coniferous rain forests dominated by kauri vegetation flourished in a raised bog setting present temperate climate and kauri vegetation of new zealand are considered to be the modern analog to the gippsland basin the coniferous vegetation provided large quantities of hydrogen rich exinite macerals such as cutinite and resinite with potential to generate oil high rainfall raised ground water level low oxygen high acidity and low nutrient conditions of a raised bog setting were suitable for preserving organic matter a comparison of gas chromatograms of oils in the gippsland basin with gas chromatograms of oils generated by hydrous pyrolysis in the laboratory from the immature source rocks suggests that the paraffinic fraction of the oil was derived from coal and the naphthenic fraction was derived chiefly from resin

application of aromatic compounds as maturity indicators in source rocks and crude oils concentration ratios of aromatic compounds such as naphthalenes phenanthrenes and dibenzothiophenes are at present attracting increasing attention as maturity indicators in sedimentary rocks and crude oils generally these indicators rely either on an increase with maturity in the degree of alkylation of a given parent compound or a shift in the isomer distribution of alkyl aromatic homologues towards thermally more stable isomers a combination of both concepts in the methylphenanthrene index mpi resulted in an excellent maturity parameter as demonstrated for rock extracts by an improved correlation with mean vitrinite reflectance rm between 0 65 and 1 4 i e in the zone of oil formation in cases that rm measurements were ambiguous this empirical relationship has proved useful in the calculation of theoretical vitrinite reflectance rc values from the mpi on the other hand for potential petroleum source rocks reaching maturity at relatively low temperatures the influence of the organic matter type on the aromatic distributions cannot be neglected consequently organic facies effects should be taken into account in the interpretation of aromatic distributions of such source rocks and related crude oils since the impact of the organic facies is strongly reduced with increasing maturity aromatic maturity parameters are particularly useful in the maturity evaluation of post mature crude oils and condensates in contrast to biological markers substantially higher concentrations of the key alkyl aromatics persist at elevated maturation levels thus aromatic maturity parameters should be considered as versatile tools in organic maturation studies and can complement established maturity indicators based on steranes and terpanes

heat flow in the piedmont and atlantic coastal plain of the southeastern united states seventy four new heat flow values have been determined at sites from new jersey to georgia mostly in the piedmont and atlantic coastal plain provinces relatively high heat flows are characteristic of synmetamorphic and postmetamorphic granites exposed in the piedmont and occurring in the basement beneath the sediments of the atlantic coastal plain the piedmont heat flow and heat generation values determined in granites metagranites and one slate belt site lie in a belt approximately parallel to major structural trends in the appalachians these values fall on or near the regression line q mw m 2 29 8 n 1 5 mw m 2 7 8 km n 0 475a w m 3 r 0 97477 it is proposed that the occurrence of a thrust fault that truncates granites at a depth d of 7 8 km is directly responsible for this linear relation in the eastern piedmont basement core from beneath the sediments of the atlantic coastal plain was recovered at ten sites results from five of these sites plus one site in the baltimore gabbro define a second linear relation with a slope d 8 0 q 0 380 km r 0 99550 approximately parallel to the piedmont relation but with an intercept of 48 2 0 8 mw m 2 these two relations may represent different heat flow provinces in the southeastern united states or the linear relations may simply be a consequence of differences in the thicknesses of the upper heat producing layer at least as far east as postmetamorphic granites sampled under the coastal plain

heterogeneity of oil composition within a reservoir as a reflection of accumulation history abstract the unaltered petroleums of a small oil field in the f r germany reveal pronounced spatial heterogeneities in bulk and molecular composition over most of the field area the oil in high porosity high permeability sand intervals bears a higher proportion of saturated hydrocarbons and has a higher maturity chemical signature as compared to oils occupying lower porosity lower permeability zones for all sands with less than about 13 porosity a regular relationship was observed between oil composition and porosity permeability with a decrease of the latter petrophysical properties increasingly lower chemical maturities and increasingly different bulk chemical compositions lower proportions of saturated hydrocarbons and higher proportions of nso compounds were recorded maximum contrasts measured for chemical maturities are e g 0 63 versus 0 82 vitrinite reflectance equivalents rc values calculated on the basis of the methylphenanthrene index according to radke and welte 1983 0 31 versus 0 84 for the ratio of triaromatic to mono plus triaromatic steroid hydrocarbons and 0 38 versus 0 47 for the 20s 20s 20r ratio of c29 5 h 14 h 17 h steranes these spatial heterogeneities in the composition of the oils are interpreted to reflect 1 i successive stages of trap filling due to episodes of increasing burial and maturation of the relevant source rocks in combination with 2 ii low rates of in reservoir mixing of these individual oil charges by convection or diffusion recognition of compositional heterogeneities within the oil column of individual fields may not only provide a basis for the reconstruction of reservoir filling history but may also have important implications for improving petroleum production

biomarker signatures from neoproterozoic early cambrian oil western india abstract the neoproterozoic early cambrian time is the cradle of multicellular eukaryotic life and thereafter metazoan life started populating the planet biomarkers which record the chronicles of biotic events on earth have been investigated using gas chromatography mass spectrometry from a suite of nine oil samples extracted from oil stained sediments and a crude oil of neoproterozoic early cambrian age from bikaner nagaur basin western india the biomarker distribution is characterized by high concentration of both tricyclic terpanes and pentacyclic hopanes the predominance of c 29 regular sterane over c 27 and c 28 steranes indicates green algal contribution and may imply the prominence and diversification of the same algal group the low pristane phytane ratio and occurrence of substantial quantity of gammacerane monomethyl 2 methyl 2 2 4 8 trimethyltridecyl chroman and 1 1 7 8 tetramethyl 1 2 3 4 tetrahydrophenanthrene are indicative of stratified water column as well as anoxic and enhanced salinity condition of the environment of deposition this paper reports for the first time the presence of methyltrimethyltridecyl chromans mttcs from neoproterozoic early cambrian time putative c 19 norsteranes probably indicative of sponge input are recorded in the studied samples and also reported from other infracambrian oils and sediments normal alkanes n c 17 and n c 18 and isoprenoids pristane and phytane are highly depleted in 13 c the overall biomarker distribution and carbon isotope data of oils from bikaner nagaur basin show similarities with those of other infracambrian oils like huqf oils from oman and baykit high oils from eastern siberia

molecular markers carbon isotopes and rare earth elements of highly mature reservoir pyrobitumens from sichuan basin southwestern china implications for precambrian lower cambrian petroleum systems abstract the moxi gaoshiti bulge of the sichuan basin in southwestern china is unique because it provides insights into the geochemistry of lower cambrian reservoir bitumens and their geological significance for paleo oil reservoirs analyses of biomarkers carbon isotopes trace elements te and rare earth elements ree were conducted on reservoir bitumens and the associated source rocks to constrain sedimentary environments and bitumen paleo oil sources based on biomarkers carbon isotopes te ratios and ree distribution patterns both of the cambrian qiongzhisi 1q and sinian dengying z2dn source rocks can be hydrocarbon sources for the cambrian longwangmiao 1l bitumens in the mg bulge lower cambrian doushantuo formation not discussed here abundant n alkanes relative to isoprenoids significant c21 and c22 steranes predominance of dibenzothiophene dbt and low ratios of biomarkers such as pr ph dbt p c22tt c21tt and c35h 22s c34 h 22s indicated that the source rock was characterized as shale from an overall highly reducing marine depositional environment the average 13c values from the compositions of the solid bitumens show an abnormal order saturate hydrocarbons

geophysical evidence for an allochthonous alleghanian granitoid beneath the basement surface of the coastal plain near lumberton north carolina geophysical data obtained over the atlantic coastal plain near lumberton north carolina indicate the presence of a granitic pluton buried beneath basement volcanic rocks similar to those of the carolina slate belt the volcanic rocks were cored southeast of the city of lumberton they consist of interlayered felsic and mafic rocks metamorphosed to lower amphibolite facies excellent reflections from a nearby vibroseis line originate from this volcanic sequence which is interpreted as being 3 5 km in thickness the volcanic rocks are underlain by an acoustically transparent interval interpreted as being associated with a granitic pluton this hypothesis is supported by a 35 mgal bou guer gravity anomaly and by a relatively high heat flow of 63 5 5 4 mw m 2 obtained in the drill hole these are both characteristics of late paleozoic alleghanian granitoids in the southeastern united states results of gravity modeling suggest that the body is nearly circular in shape 45 km diam and 13 km in thickness subhorizontal reflections at 5 to 7 sec on the seismic data are interpreted as being at and below the base of the granitoid at a depth of 17 km the deep layering may be stratigraphy or mylonites and in either case the granitoid is allochthonous and did not intrude the layering high heat flow suggests from our experience in the piedmont that the body is unmetamorphosed and of late paleozoic age the thrusting may postdate or be coeval with the age of intrusion and suggests that late paleozoic thrusting in this part of the coastal plain is confined to depths below 17 km

carbon isotope excursions in precambrian cambrian boundary beds morocco the precambrian cambrian boundary is one of the most significant points on the geological timescale because it marks the change in the fossil record from soft bodied organisms to skeletonized faunas the cambrian explosion or radiation event1 saw the evolution of many new life forms especially various molluscs and archaeocyathids from the base of the cambrian tommotian stage others including the trilobites and bivalves evolved a little later in the succeeding atdabanian stage2 3 a massive increase in the biomass of the photic zone through phytoplankton blooms has also been postulated for this time4 particularly in the late riphean early vendian and in the early cambrian5 there has been much discussion concerning where precisely to place the boundary6 7 and here are several contenders in the world for the type section8 i present here a carbon isotope profile from the precambrian cambrian boundary beds in morocco where two distinctive positive 13c excursions are revealed these are interpreted as records of increased organic productivity as part of the precambrian cambrian explosion of life 13c excursions could be useful points for correlation between boundary sections

geochemical study on a well in the western canada basin relation of the aromatic distribution pattern to maturity of organic matter abstract thirty one rock samples from a western canada basin well have been analysed for aromatics using glass capillary gas chromatography with simultaneous flame ionization and sulfur selective flame photometric detection a uniform aromatic distribution pattern with a marked predominance of di and tricyclic aromatic hydrocarbons was observed throughout a depth interval of 3000 meters comprising cretaceous and jurassic sediments the very high relative abundance of sulfur aromatics at two narrow intervals in the triassic and mississippian is attributed to a major change in facies gradual changes with increasing depth have been observed for a series of compound ratios which had been calculated from the isomers of methyl and dimethylphenanthrene and their parent compounds these changes reflect the increasing thermal maturation of the sedimentary organic matter a methylphenanthrene index mpi has been introduced which exhibited a very good correlation with vitrinite reflectance data the mpi is the first maturity parameter which is based on a series of aromatic hydrocarbons this hydrocarbon internal maturity parameter permits the recognition and definition of maturity levels in extracts which can be compared to the maturity e g vitrinite reflectance of source rocks

the ratios of dibenzothiophene to phenanthrene and pristane to phytane as indicators of depositional environment and lithology of petroleum source rocks abstract the ratio of dibenzothiophene to phenanthrene and the ratio of pristane to phytane when coupled together provide a novel and convenient way to infer crude oil source rock depositional environments and lithologies such knowledge can significantly assist in identifying the source formation s in a basin thereby providing valuable guidance for further exploration the ability to infer this information from analysis of a crude oil is especially valuable as frequently the earliest samples in a new area may be shows and or drill stem test samples from exploratory wells which are characteristically drilled on structural highs stratigraphically remote from the source formation s a cross plot of dibenzothiophene phenanthrene versus the pristane phytane ratios measured on seventy five crude oils from forty one known source rocks ranging in age from ordovician to miocene consistently classified the oils into the following environment lithology groups marine carbonate marine carbonate mixed and lacustrine sulfate rich lacustrine sulfate poor marine and lacustrine shale and fluvial deltaic carbonaceous shale and coal the dibenzothiophene phenanthrene ratio alone is an excellent indicator of source rock lithology with carbonates having ratios 1 and shales having ratios the dibenzothiophene to phenanthrene and the pristane to phytane ratios can also be used to classify source rock paleodepositional environments the classification scheme is based on the premise that these ratios reflect the different eh ph regimes resulting from the significant microbiological and chemical processes occurring during deposition and early diagenesis of sediments the dibenzothiophene phenanthrene ratio assesses the availability of reduced sulfur for incorporation into organic matter and the pristane phytane ratio assesses the redox conditions within the depositional environment interpretation of these ratios has been aided by quantitative biomarker analysis and by carbon isotope data for pristane and phytane obtained by gas chromatography isotope ratio mass spectrometry

origin of petroleum in the neoproterozoic cambrian south oman salt basin abstract the south oman salt basin sosb is host to the world s oldest known commercial deposits most of the south oman oils have been proven to be associated with the source rocks of the neoproterozoic to cambrian huqf supergroup but the assignment of oils to specific huqf intervals or facies has been hampered by the geochemical similarity of the organic matter across the entire huqf sequence possibly as a consequence of limited change in the local palaeoenvironment and biota over the time of its deposition this study was conducted to establish improved correlations between organic rich rock units and reservoir fluids in the sosb through detailed molecular and isotopic analysis of the huqf supergroup with special emphasis directed towards understanding the ara carbonate stringer play unusual biomarkers tentatively identified as a norsteranes show distinctive patterns among carbonate stringer oils and rocks different from those observed in nafun sediments and ara rocks from the athel basin these putative a norsteranes form the basis for new oil source correlations in the sosb and provide for the first time geochemical evidence of a self charging mechanism for the carbonate stringer play the paucity of markers specific to the nafun group shuram buah and masirah bay formations confounds attempts to quantify their respective contributions to huqf oil accumulations nafun inputs can only be determined on the basis of subtle differences between nafun and ara biomarker ratios the most useful geochemical characteristics delineating nafun group organic matter from ara group intra salt source rocks included low relative abundance of mid chain monomethyl alkanes x compounds low relative abundance of gammacerane 28 30 dinorhopane 25 28 30 trinorhopane and 2 methylhopanes low c 22 t c 21 t and high c 23 t c 24 t cheilanthanes ratio values based on these parameters molecular evidence for major contributions of liquid hydrocarbons from nafun group sediments shuram buah and masirah bay formations is lacking our results suggest that the majority of sosb hydrocarbon accumulations originate from within the ara group either from the carbonate stringers or from the package of sediments that comprises the thuleilat athel silicilyte and u shale formations subtle aspects of the composition of some carbonate stringer and post salt huqf oils could suggest some degree of sourcing from the nafun rocks but stronger evidence is needed to confirm this

the significance of 24 norcholestanes triaromatic steroids and dinosteroids in oils and cambrian ordovician source rocks from the cratonic region of the tarim basin nw china abstract two oil families in ordovician reservoirs from the cratonic region of the tarim basin are distinguished by the distribution of regular steranes triaromatic steroids norcholestanes and dinosteroids oils with relatively lower contents of c 28 regular steranes c 26 20s c 26 20r c 27 20s and c 27 20r regular triaromatic steroids dinosteranes 24 norcholestanes and triaromatic dinosteroids originated from middle upper ordovician source rocks in contrast oils with abnormally high abundances of the above compounds are derived from cambrian and lower ordovician source rocks only a few oils have previously been reported to be of cambrian and lower ordovician origin especially in the east region of the tarim basin this study further reports the discovery of oil accumulations of cambrian and lower ordovician origin in the tabei and tazhong uplifts which indicates a potential for further discoveries involving cambrian and lower ordovician sourced oils in the tarim basin dinosteroids in petroleum and ancient sediments are generally thought to be biomarkers for dinoflagellates and 24 norcholestanes for dinoflagellates and diatoms therefore the abnormally high abundance of these compounds in extracts from the organic rich sediments in the cambrian and lower ordovician and related oils in the cratonic region of the tarim basin suggests that phytoplankton algae related to dinoflagellates have appeared and might have flourished in the tarim basin during the cambrian period steroids with less common structural configurations are underutilized and can expand understanding of the early development history of organisms as well as define petroleum systems

paleozoic and grenvillian structures in the southern appalachians extended interpretation of seismic reflection data interpretive reprocessing of seismic reflection data has elucidated paleozoic and grenvillian structures in the southern appalachians the seismic data include a 7500 km grid of adcoh seisdata and cocorp reflection profiles that traverse the blue ridge and inner picdmont geologic provinces of north carolina south carolina and georgia surface geology and potential field data were used to constrain the interpretation the reprocessed seismic reflection data have delineated the internal and external geometry of the crystalline blue ridge inner piedmont allochthon including the locations of the blue ridge master decollement haycsville fault and brevard fault zone on the basis of the reprocessed data all of the major faults within the allochthonous upper crust sole in the blue ridge master decollement reflections extending to the southeast from beneath the surface location of the hayesville fault to the blue ridge thrust might be the seismic signature of a high strain zone this implies that internal deformation of the blue ridge allochthon associated with the alleghanian orogeny might have occurred farther to the west than has been previously documented from field studies relative amplitude seismic data enabled the discrimination between blue ridge inner piedmont crystalline rocks and underlying lower paleozoic shelf strata thereby delineating the blue ridge thrust the interpreted geometry constrains the top of the shelf sequence beneath the blue ridge to depths of less than 3 km this relatively shallow depth of the shelf strata together with the presence of duplex structures and bright spots that are imaged within the sequence might imply favorable conditions for hydrocarbon exploration beneath the blue ridge midcrustal reflections from within the upper to iower crust are interpreted to originate from preserved grenvillian structures that were reactivated at the basement surface during late proterozoic early cambrian extension reflection continuity is occasionally disrupted by interpreted post grenvillian pre early cambrian low density intrusions topography at the basement surface possibly caused by the intrusions is interpreted to have controlled the formation of some of the structures within the overlying allochthon including blue ridge and brevard fault zone ramps correlation of seismic time structure contour maps with available gravity data and two dimensional gravity modeling suggest that anomalies in the gravity field can be attributed to low density sources within the autochthonous crust discontinuous reflection packages from depths of 36 42 km are interpreted to originate from the mohorovi i discontinuity the reflectors trend about n15 e with a true dip of approximately 15 nw

occurrence and composition of solid bitumens from the bulonggoer devonian paleo oil reservoir north xinjiang china abstract the bulonggoer paleo oil reservoir bpr on the northwest junggar basin is the first devonian paleo oil reservoir discovered in north xinjiang china solid bitumens occur within sandstone pores and as veins filling fractures samples of both types were analyzed using stable carbon isotope and reflectance measurements as well as molecular biomarker parameters the extremely positive 13 c values and biomarker indicators of depositional environment lithology such as pristane phytane pr ph c 29 c 30 hopane diasteranes regular steranes and dibenzothiophene phenanthrene ratios indicate a siliciclastic source for the bpr and their deposition in a highly reducing hypersaline environment the presence of long chain n alkanes and abundant tetracyclic diterpanes c 20 c 21 tricyclic terpanes and perylene are indicators of higher plant organic matter input moreover the bimodal distribution of c 27 c 28 29 regular steranes and abundant methyltriaromatic steroids also support a contribution of microalgae as well as higher plants organic matter the similar molecular composition and thermal maturity parameters indicate that the reservoir and veined solid bitumens were altered from a common paleo petroleum which originated from peak oil window matured source rocks all solid bitumens from the bpr are characterized by relatively low bitumen reflectance values rb

saturate biomarkers and aromatic sulfur compounds in oils and condensates from different source rock lithologies of kazakhstan japan and russia abstract representative petroleums from the seven basins of kazakhstan russia and japan were analyzed using gas chromatography with dual fid fpd and gc ms the present study has shown that the deviation in relative concentrations of aromatic sulfur compounds in petroleums could be related to the type of source rock all oil samples were classified into three groups on the basis of the relative abundance of aromatic sulfur compounds biomarker distribution and lithology of source rock the first group of oils derived from carbonate source rocks is rich in aromatic sulfur compounds such as methylbenzothiophenes mbt and methyldibenzothiophenes mdbt and poor in dibenzothiophene dbt compared to methylated homologs the second group derived from siliceous and siliceous carbonate source rocks contains various types of benzothiophenes and dibenzothiophenes including dbt the third group originating from argillaceous rocks has lower concentrations of aromatic sulfur compounds and especially of methylated benzothiophenes

source characterization of highly mature pyrobitumens using trace and rare earth element geochemistry sinian paleozoic paleo oil reservoirs in south china abstract understanding the relationships between migrated hydrocarbons and source rocks under highly mature conditions i e pyrobitumen source correlation is a critical and challenging issue in the field of petroleum geology and geochemistry based on a case study of three sinian paleozoic paleo oil reservoirs from yunan and guizhou provinces south china we attempt to provide further understanding of this issue using trace and rare earth element ree geochemistry which can characterize the depositional setting organic input and rock provenance of source rocks results show that the bitumens from the three paleo oil reservoirs can be distinguished from each other using post archean australian shale paas normalized trace element distribution patterns ree distribution patterns hierarchal cluster analysis of element concentrations and redox and provenance sensitive elemental ratios e g v ni ni co ni mo zr cr la sc and la co pyrobitumen in the devonian xiaocaoba paleo oil reservoir is derived primarily from devonian source rocks representing a self sourced petroleum system and one stage hydrocarbon charging similarly pyrobitumen in the sinian jinsha yankong paleo reservoir also received a single fluid charge but the source is different and likely generated by contributions from both lower cambrian and sinian sources in contrast the bitumen in ordovician kaili luomian paleo reservoirs are indicated to have contributions from two different hydrocarbon sources and thus experienced two stages of hydrocarbon charging an early charge from lower cambrian source rocks and a later charge from permian source rocks the new trace and rare earth element method used in this study appears to be effective at providing a better understanding of the hydrocarbon source correlation under highly mature conditions the results improve our understanding of the complex hydrocarbon accumulation alteration evolution in the marine strata of south china which is a potential target for petroleum exploration

evaluating rare earth elements as a proxy for oil source correlation a case study from aer sag erlian basin northern china abstract the use of rare earth elements ree for oil source correlation has not yet been established in order to evaluate the potential of ree as proxies for oil source correlation we used traditional correlation approaches including biomarkers and trace elemental ratios v ni and ni co to identify the source rock of oil sands using isolated organic extracts of mudstones and oil sands and by analyzing the organic extracts and their corresponding whole rock material for ree compositions by inductively coupled plasma mass spectrometry icp ms oil source correlations using ree were not consistent with conclusions based on biomarker data and trace element ratios only one pair of oil source rock relationship was successfully established using ree ree concentrations of crude oils could possibly be controlled by the quantities of metal complexes and functional groups that provide complexing sites for v and ree as well as secondary alteration processes e g thermal alteration and biodegradation ree patterns might be linked to the organic matter types of source rocks although an accurate oil source relationship failed to be established using ree in this study ree could potentially be a novel complementary proxy for oil oil and or oil source correlations when supplemented by traditional correlation approaches including biomarkers

relationship between inferred redox potential of the depositional environment and geochemistry of the upper pennsylvanian missourian stark shale member of the dennis limestone wabaunsee county kansas u s a analyses of 21 samples collected from a core of the 52 8 cm thick stark shale member of the dennis limestone in wabaunsee county kansas demonstrate four cycles with two orders of magnitude variations in contents of cd mo p v and zn and order of magnitude variations in contents of organic carbon cr ni se and u the observed variability in amounts and or ratios of many metals and amounts and compositions of the organic matter appear related to the cause and degree of water column stratification and the resulting absence presence of dissolved o2 or h2s high cd mo u v zn and s contents a high degree of pyritization dop 0 75 0 88 and high high v v ni 0 84 0 89 indicate the presence of h2s in a strongly stratified water column intermediate contents of metals and s intermediate dop 0 67 0 75 and intermediate v v ni 054 0 82 indicate a less strongly stratified anoxic water column whereas low metal contents and low v v ni 0 46 0 60 indicate a weakly stratified dysoxic water column high p contents at the top of the organic matter rich intervals within the stark shale member indicate that phosphate precipitation was enhanced near the boundary between anoxic and dysoxic water compositions relatively abundant terrestrial organic matter in intervals deposited from the more strongly stratified h2s bearing water column indicates a combined halocline thermocline with the fresher near surface water the transport mode for the terrestrial organic matter the predominance of algal organic matter in intervals deposited from a less strongly stratified water column indicates the absence of the halocline and the presence of the more generally established thermocline relatively low amounts of degraded hydrogen poor organic matter characterize intervals deposited in a weakly stratified dysoxic water column the inferred variability in chemistry of the depositional environments may be related to climate variations and or minor changes in sea level during the general phase of deeper water deposition responsible for this widespread shale member