geochemistry of petroleum systems in the niuzhuang south slope of bohai bay basin part 4 evidence for new exploration horizons in a maturely explored petroleum province abstract significant oil reserves have been discovered recently in the ek1 member of the paleocene eocene kongdian formation and the ordovician buried hill reservoirs in the basement of the niuzhuang south slope nss dongying depression bohai bay basin the physical properties and chemical compositions of these oils are different from those in the overlying eocene oligocene shahejie formation es displaying high wax 29 32 low sulfur 0 04 0 25 and high sterane isomerization ratios 0 46 0 52 for c29 sterane 20s 20s 20r in contrast the es reservoired oils have relatively low wax but high sulfur contents with the 20s 20s 20r ratio for c29 steranes in the range of 0 33 0 39 oil source correlation results show that the es reservoired oils were derived from source rocks in the es4 member of the shahejie formation within the conventional oil window whereas the dominance of c29 steranes observed in oils from the ek1 and ordovician reservoirs suggests a contribution from different source s for these oils within the deep es4 interval and the ek2 member of the kongdian formation the recent commercial oil discovery in the ek1 and older strata and the confirmation of the presence of organic rich dark mudstones in the ek2 member of the kongdian formation are significant for further petroleum exploration in the deep strata of the dongying depression and other parts of the bohai bay basin

timing and style of late pleistocene glaciation in the queer shan northern hengduan mountains in the eastern tibetan plateau glacial landforms and sediments provide evidence for the existence of two late pleistocene major glacial advances in the queer shan northern hengduan mountains in the eastern tibetan plateau in the current study optically stimulated luminescence and electron spin resonance dating results reveal that the two glacial advances occurred during marine isotope stage mis 3 and the last glacial maximum lgm in mis 2 respectively geomorphic evidence shows that the glacial advance during mis 3 was more extensive than that in mis 2 this glacial advance is synchronous with other glaciated areas in the himalaya and tibet but contrasts with global ice volumes that reached their maximum extent during the lgm glaciers in the queer shan are of the summer accumulation type and are mainly fed by precipitation from the south asian monsoon palaeoclimate proxies show that during mis 3 the south asian monsoon strengthened and extended further north into the tibetan plateau to supply more precipitation as snow at high altitudes this in turn led to positive glacier mass balances and caused glaciers to advance however during the lgm despite cooler temperature than in mis 3 the weakened south asian monsoon and the associated reduced precipitation were not as favourable for glacier expansion as in mis 3 copyright c 2010 john wiley sons ltd glacial landforms and sediments provide evidence for the existence of two late pleistocene major glacial advances in the queer shan northern hengduan mountains in the eastern tibetan plateau in the current study optically stimulated luminescence and electron spin resonance dating results reveal that the two glacial advances occurred during marine isotope stage mis 3 and the last glacial maximum lgm in mis 2 respectively geomorphic evidence shows that the glacial advance during mis 3 was more extensive than that in mis 2 this glacial advance is synchronous with other glaciated areas in the himalaya and tibet but contrasts with global ice volumes that reached their maximum extent during the lgm glaciers in the queer shan are of the summer accumulation type and are mainly fed by precipitation from the south asian monsoon palaeoclimate proxies show that during mis 3 the south asian monsoon strengthened and extended further north into the tibetan plateau to supply more precipitation as snow at high altitudes this in turn led to positive glacier mass balances and caused glaciers to advance however during the lgm despite cooler temperature than in mis 3 the weakened south asian monsoon and the associated reduced precipitation were not as favourable for glacier expansion as in mis 3 copyright c 2010 john wiley sons ltd

diagenetic and catagenetic products of isorenieratene molecular indicators for photic zone anoxia a wide range of novel diagenetic and catagenetic products of the diaromatic carotenoid isorenieratene a pigment of the photosynthetic green sulphur bacteria chlorobiaceae has been identified in a number of sedimentary rocks ranging from ordovician to miocene compound identification is based on nmr mass spectrometry the presence of atropisomers and stable carbon isotopes atropisomers contain an axially chiral centre which in combination with other chiral centres results in two or more diastereomers that can be separated on a normal gc column chlorobiaceae use the reverse tca cycle to fix carbon so that their biomass is enriched in 13c high 13c contents of isorenieratene derivatives therefore support their inferred origins isorenieratene derivatives include c 40 c 33 and c 32 diaryl isoprenoids and short chain aryl isoprenoids with additional aromatic and or s containing rings c 33 and c 32 compounds are diagenetic products of c 33 and c 32 carotenoids formed from isorenieratene during early diagenesis through expulsion of toluene and m xylene respectively cyclisation of the polyene acyclic isoprenoid chain can proceed via an intramolecular diels alder reaction followed by aromatisation of the newly formed ring sulphurisation is also an important process during early diagenesis competing with expulsion and cyclisation sulphur bound isorenieratane is released during progressive diagenesis due to cleavage of relatively weak ss and cs bonds cleavage of c c bonds during aromatisation of newly formed rings and during catagenesis yields short chain compounds the inherent presence of a conjugated double bond system in carotenoids implies that similar diagenetic and catagenetic reactions can occur with all carotenoids chlorobiaceae live at or below the oxic anoxic boundary layer and require both light and h 2s the presence of isorenieratene or its diagenetic and catagenetic products in ancient sedimentary rocks and crude oils is therefore an excellent indication for photic zone anoxia in the depositional environment diagenetic and catagenetic products of isorenieratene are expected to find applications in reconstruction of palaeoenvironments and in oil oil and oil source rock correlation studies their presence in several petroleum source rocks suggests that anoxia is an important environmental parameter for the preservation of organic matter

early generation of 20s 5α h 14α h 17α h and 5α h 14β h 17β h steranes in low salinity lacustrine shales abstract a quantitative sterane biomarker study was conducted on a series of paralic freshwater lacustrine shale samples ranging in maturity from immature to near oil window maturity taken from section 3 of the shahejie formation es3 in the liaohe basin n e china concentrations of 5 h 14 h 17 h 20s and 5 h 14 h 17 h steranes remain nearly constant throughout the sample suite however the decrease in the absolute concentrations of the 20r 5 h 14 h 17 h c 29 steranes with increasing maturity results in an increase in the conventionally defined maturity parameters 20s 20 s 20r and sterane ratios in addition the data suggest that relatively early generation of 5 h 14 h 17 h 20s and 5 h 14 h 17 h steranes has occurred in lacustrine sediments with a vitrinate reflectance 0 3 r o the data provide strong support for the major importance of relative thermal stability of epimers but do not exclude the possibility of isomerization as a viable mechanism for production

origin of crude oils in the jinhu depression of north jiangsu south yellow sea basin eastern china abstract the chemical compositions of 20 crude oils and the extracts of potential source rocks from the jinhu depression of the north jiangsu south yellow sea basin eastern china were studied in detail by geochemical methods in order to understand their genetic relationship the oil samples were collected from the major producing fields in the western slope ws and the biandong yangjiaba minqiao uplift belt bmy the rock samples studied selected after rock eval pyrolysis screening of a large suite of samples consist of 20 shale samples in the e 2 f 2 member of the paleocene funing formation from the oilfield areas ws and bmy and the sanhe sag all within the jinhu depression geochemical characteristics indicate only one single family of oils a number of biomarker features support deposition of the source rocks for these oils under conditions of enhanced salinity stratified water columns a wide thermal maturity range for the oils as indicated by sterane isomerization ratios was not substantiated by other maturity parameters the genetic relationships between the oils and the e 2 f 2 member of the paleocene funing formation present in the deeper parts of the sanhe and longgang sags were suggested using a wide range of molecular parameters variation in the sterane concentrations in source rocks with different maturity suggests that migrational contamination and or in situ extractions of organic matter from caprocks or intra reservoir shales by mature oils could potentially produce oils with apparent immaturity at the molecular level secondary alteration e g biodegradation of oils in the reservoir could also have a similar effect on the bulk oil compositions although we do not discount the possible presence of minor amounts of immature oils exploration focus in the jinhu depression as well as many other rift basins in eastern china should be on mature oils derived from the deep source kitchens

origin of the unusually high dibenzothiophene oils in tazhong 4 oilfield of tarim basin and its implication in deep petroleum exploration abstract unusually high dibenzothiophene dbt concentrations are present in the oils from the tazhong 4 oilfield in the tazhong uplift tarim basin positive ion electrospray ionization fourier transform ion cyclotron resonance mass spectrometry ft icr ms was used in combination with conventional geochemical approaches to unravel the enrichment mechanisms significant amounts of s1 species with relatively low dbe values 0 8 i e sulfur ethers mercaptans thiophenes and benzothiophenes were detected in three lower ordovician oils with high thermal maturity which were suggested to be the products of thermochemical sulfate reduction tsr in the reservoir the occurrence of tsr was also supported by the coexistence of thiadiamondoids and abundant h2s in the gases associated with the oils obviously low concentrations of the dbe 9 s1 species mainly equivalent to c0 c35 dbts compared to its homologues were observed for the three oils which were probably altered by tsr indicating that no positive relationship existed between tsr and dbts in this study the sulfur compounds in the tazhong 4 oils are quite similar to those in the majority of lower ordovician oils characterized by high concentrations of dbts and dominant dbe 9 s1 species with only small amounts of sulfur compounds with low thermal stability dbe 0 8 suggesting only a small proportion of sulfur compounds were derived from tsr it is thermal maturity rather than tsr that has caused the unusually high dbt concentrations in most of the lower ordovician oils we suggest that the unusually high dbt oils in the tazhong 4 oilfield are caused by oil mixing from the later charged lower ordovician or perhaps even deeper with high dbt abundances from the earlier less mature oils which was supported by our oil mixing experiments and previous relevant investigations as well as abundant authigenic pyrite of hydrothermal origin we believe that tsr should have occurred in the tazhong uplift based on our ft icr ms results however normal sulfur compounds were detected in most oils and no increase of 13c2h6 13c4h10 was observed for the gas hydrocarbons suggesting only a slight alteration of the oils by tsr currently and or recently we suspect that the abnormal sulfur compounds in the lower ordovician oils might also be a result of deep oil mixing which might imply a deeper petroliferous horizon i e cambrian with a high petroleum potential this study is important to further deep petroleum exploration in the area

geochemistry of petroleum systems in the niuzhuang south slope of bohai bay basin part 1 source rock characterization detailed mapping of the tertiary strata of the dongying depression bohai bay basin reveals that oil shales and dark mudstones in the es4 and es3 members of the eocene oligocene shahejie formation have excellent potential as petroleum source rocks regional distributions of total organic carbon content kerogen type and thermal maturation indicate that abundant mature source rocks are present in the niuzhuang sag whereas source rocks along the niuzhuang south slope are currently immature or marginally mature for the generation of conventional oils this study examined the molecular characteristics for a number of biomarker compound classes and related these to either source facies change or different burial and thermal maturation an important observation made during this study is the significant variation in the relative distributions and absolute concentrations of a wide range of aliphatic and aromatic hydrocarbon markers in the rock extracts as a function of burial depth this variation may potentially explain the uncertainty associated with the maturity assessment and genetic modeling for so called immature oils that are usually defined on the basis of alkane biomarker isomerization ratios and the presence of biomarkers with biological configurations

quaternary glaciations and glacial landform evolution in the tailan river valley tianshan range china abstract the tailan river originates on the southern slope of tumur peak the largest center of modern glaciation in the tianshan range five moraine complexes and associated fluvioglacial deposits in this valley record a complex history of quaternary glacial cycles and landform evolution electron spin resonance esr dating of glacial sediments was carried out using germanium ge centers in quartz grains which are sensitive to both sunlight and grinding based on the dating results as well as geomorphic and stratigraphic data the piyazilike end moraines the second moraine complex were deposited during neoglaciation the largest glacial advances during the last 3 4 ka in western china and an early holocene glacial advance the third set of moraines was deposited in marine isotope stage mis 2 4 and the glacial landforms of the tailan glaciation the fourth moraine complex which include hummocky moraines on the piedmont were formed in mis 6 penultimate glaciation the end moraines of the innermost moraine complex the first moraine complex are inferred to have been deposited during the little ice age lia thus the landforms and dates indicate compound valley glaciers from the lia to mis 2 4 and piedmont glaciers during mis 6 the oldest tills studied belong to the kokdepsang glacial stage and occur on a high plateau based on similar glacial landforms glacial deposits on a high plateau and a high glacial terrace and their esr ages in adjacent valleys on the southern slope of tumur peak the kokdepsang glacial stage is assigned to mis 12

late cenozoic uplift of mountain ranges and global climate change chicken or egg the high altitudes of most mountain ranges have commonly been ascribed to late cenozoic uplift without reference to when crustal thickening and other tectonic processes occurred deep incision and recent denudation of these mountain ranges abundant late cenozoic coarse sediment near them and palaeobotanical evidence for warmer climates where high mountain climates today are relatively cold have traditionally been interpreted as evidence for recent uplift an alternative cause of these phenomena is late cenozoic global climate change towards lower temperatures increased alpine glaciation a stormier climate and perturbations to humidity vegetative cover and precipitation

assessing the relative efficiency of fluvial and glacial erosion through simulation of fluvial landscapes the relative rates of erosion by rivers and glaciers and the topographic effects of these two different styles of erosion remain outstanding problems in geomorphology we use a quantitative description of local fluvial landscapes to estimate how glaciated landscapes might look now had glaciers not developed this indicates the landscape modification attributable to glacial erosion we present examples from the sierra nevada california and the sangre de cristo range colorado in smaller drainage basins glacial modification is focussed above the mean quaternary equilibrium line altitude ela where both ridgelines and valley floors have been lowered as a consequence of glaciation at lower elevations small glaciers have apparently widened valleys without incising the valley floor beyond what a river would have this may reflect the short residence time of the glaciers at their full extent or differences in the subglacial drainage network between the glacier margins and the thalweg in larger drainage basins the pattern of glacial erosion is dramatically different here the glaciers have modified longitudinal profiles as well as valley cross sections far below the mean quaternary ela possible causes of this difference in the larger basins include the larger accumulation area greater shading of the valley floor longer residence times for ice at its full extent and the influence of the shallower valley slope prior to glaciation on the subsequent glacier and subglacial drainage conditions

esr dating in quaternary geology abstract electron spin resonance esr a relatively new dating technique was first suggested by zeller et al 1967 zeller 1968 and levy 1968 it has made substantial progress in frequent applications in the last few years esr dating is based on the direct measurement of the amount of radiation induced paramagnetic electrons trapped in crystal defects these free electrons were generated by alpha beta and gamma radiation of natural radioelements e g u th k and have accumulated in the minerals over geologic time the esr age is obtained by dividing the total amount of accumulated radiation dose archaeological dose ad by the dose per year annual dose this review comprises four major parts the principles of the method the determination of the archaeological dose ad the determination of the annual dose and a compilation of datable materials several questions remain the evaluation of the ad the determination of the annual dose and particularly with respect to the nature and stability of the electron traps used for dating

the variety of subaerial active salt deformations in the kuqa fold thrust belt china constrained by insar abstract surface salt bodies in the western kuqa fold thrust belt of northwestern china allow study of subaerial salt kinematics and its possible correlations with weather variations ephemeral subaerial salt exposure during the evolution of a salt structure can greatly impact the subsequent development and deformation of its tectonic setting here we present a quantitative time lapse survey of surface salt deformation measured from interferometric synthetic aperture radar insar using envisat radar imagery acquired between 2003 and 2010 time series analysis and inspection of individual interferograms confirm that the majority of the salt bodies in western kuqa are active with significant insar observable displacements at 3 of 4 structures studied in the region subaerial salt motion toward and away from the satellite at rates up to 5 mm yr with respect to local references rainfall measurements from the tropical rainfall measuring mission trmm and temperature from a local weather station are used to test the relationship between seasonality and surface salt motion we observe decoupling between surface salt motion and seasonality and interpret these observations to indicate that regional and local structural regimes exert primary control on surface salt displacement rates

the role of the indian summer monsoon and the mid latitude westerlies in himalayan glaciation review and speculative discussion new dates for late quaternary glaciations in the himalayas show that during the last glacial cycle glaciations were not synchronous throughout the region rather in some areas glaciers reached their maxima at the global glacial maximum of c 18 20 ka bp whereas in others glaciers were most extensive at c 60 30 ka bp comparison of these data with palaeoclimatic records from adjacent regions suggest that on millennial timescales himalayan glacier fluctuations are controlled by variations in both the south asian monsoon and the mid latitude westerlies

glacial geomorphology and glacial history of the muzart river valley tianshan range china abstract the muzart river originates on the southeastern slope of tumur peak the largest center of modern glaciation in the tianshan range glacial landforms and sediments indicate that there are four major quaternary glaciations in this drainage the glacial landforms contain considerable information about the changes of the ancient glaciers dating the landforms allows the temporal and spatial variations of the ancient glaciers in this valley to be understood and provides essential information in reconstructing the paleoenvironment in this region electron spin resonance esr dating of a well exposed section the multiple end moraines of the pochengzi glaciation the third set of moraines and the local outwash and fluvial sediments on the kezibulake glacial plain the fourth set of moraines was carried out using germanium ge centers in the glacial quartz grains which are sensitive to both sunlight and grinding eleven depositional ages have been determined based on the dating results the principle of superposition and the glaciations pattern reported in the adjacent valley the pochengzi end moraines were determined to be deposited during the major glacial intervals that are equivalent in age to marine oxygen isotope stages mis 2 mid mis 3 and mis 4 and the kezibulake glacial deposits were determined to be equivalent in age to mis 6 furthermore the tugaibieliqi end moraine the second set of moraines was deposited during the neoglaciation a cold period between 3 and 4 ka and the 3 4 end moraines located at the terminuses of the modern glacier were deposited during the little ice age the ages of the pochengzi glacial deposits can be subdivided into three clusters they are 13 6 25 3 ka 39 5 40 4 ka and 64 2 71 7 ka respectively the largest local last glacial maximum lgm l occurred during mis 4 rather than the global last glacial maximum lgm g of mis 2 furthermore a glacier that is slightly larger than that of mis 2 developed in this drainage during mid mis 3 the ancient muzart glaciers were compound valley glaciers during the neoglaciation mis 2 and mid mis 3 and piedmont glaciers during mis 4 and mis 6

unusual polycyclic aromatic hydrocarbons in lower cretaceous ostracode zone sediments and related oils of the western canada sedimentary basin analyses of the aromatic hydrocarbon fractions of extracts of lower cretaceous ostracode zone sediments from the western canada sedimentary basin indicate the predominance of polycyclic hydroaromatic components most of these have not been previously reported in the literature but are obviously diagenetically related to a new class of molecule whose natural distribution and biological significance remain to be determined the components whose molecular structures have been confirmed together with those for which tentative structural assignments are given provide strong support for a pathway of progressive aromatisation of the presumed polyprenol precursors these compounds appear to be specific markers for the ostracode zone sourced oils in the lower mannville group reservoirs of the provost area and may serve as excellent oil source correlation parameters

molecular and isotopic evidence for mixed source oils in subtle petroleum traps of the dongying south slope bohai bay basin abstract subtle traps have become an important petroleum play type for exploration in the dongying depression bohai bay basin eastern china the majority of the oil pools are in the middle interval of the es3 member e s 3 m of the eocene oligocene shahejie formation with the subtle traps being primarily in the lenticular basin floor turbidite sands enclosed within basin floor mudstones detailed geochemical investigation of 68 oil and rock samples from the depression reveals that in contrast to previous models the oils from the subtle traps correlate poorly with the surrounding e s 3 m source rocks while the high pristane phytane pr ph 1 and low gammacerane c30 hopane ratios in these source rocks represent a freshwater lacustrine setting the oils feature low pr ph ratios e s 4 u source rocks deposited in a brackish lacustrine setting the compound specific isotope ratios of n alkanes in the oils have intermediate values between those observed in extracts from the lower es3 e s 3 l and upper es4 e s 4 u source rocks consequently the oils in the e s 3 m subtle traps were most likely derived from mixed e s 3 l and e s 4 u sources with the contribution from the e s 4 u source rocks being predominant the oils generated from the e s 4 u source rocks must have migrated through a thick interval of the e s 3 l source rocks to reach the subtle traps in the e s 3 m through which there are no apparent structural nor stratigraphic pathways the traditional migration and accumulation model i e indigenous crude oil with short migration distance to lenticular oil pools should be revised to account for the charging of oils from e s 4 u source rocks

petroleum source in the tazhong uplift tarim basin new insights from geochemical and fluid inclusion data abstract a total of 108 drill stem test dst crude oil samples and 10 reservoir fluid inclusion samples were investigated geochemically to identify the characteristics and origin of the crude oil in the tazhong uplift tarim basin nw china results show that the majority of oils share typical biomarker characteristics from the middle upper ordovician o2 3 source rock and related crude oil features these features include a distinct v shape in the relative abundance of c27 c28 and c29 regular steranes and low abundances of dinosterane 24 norcholestanes triaromatic dinosteroids and gammacerane only a few oils display typical biomarker features indicating a cambrian lower ordovician o1 genetic affinity such as linear or anti l shape c27 c28 and c29 regular sterane distributions and relatively high concentrations of dinosterane 24 norcholestanes triaromatic dinosteroids and gammacerane it appears that most of the oils studied were derived from the o2 3 intervals as suggested by previous studies however the 13c values of individual n alkanes indicate that most of the crude oils in the tazhong uplift represent a mixture of two end member oils an o1 derived oil such as from well td2 or tz62 s and an o2 3 derived oil such as from well ym2 the data suggest that most of the oils in the uplift have a mixed origin and do not originated from the middle upper ordovician strata alone this conclusion is supported by data on the molecular composition of petroleum inclusions this new oil mixing model is critical for reconstructing the hydrocarbon formation and accumulation history for the region and may have important implications for further petroleum exploration in the tarim basin

lateral moraines of glacier de tsidjiore nouve form development and implications the relationship between supraglacial lateral moraines and lateral dump moraines at arolla switzerland is discussed a detailed study of the lateral moraines of glacier de tsidjiore nouve reveals their complex form as superimposed and nested ridges and the current mode of development possibly related to the passage of a kinematic wave sedimentological analysis indicates that much of the constituent debris is of supraglacial origin it is transported either directly from the base of slopes flanking the pigne d arolla ice fall or via englacial septa comprising marginal sediment incorporated in the accumulation zone a calculation of the volume of debris in the lateral moraines suggests that glacier de tsidjiore nouve has recently been more active in transporting and depositing supraglacial debris than in glacial erosion sensu stricto

numerical modeling of the development of u shaped valleys by glacial erosion the steep sided valleys and overdeepened basins of alpine landscapes are well known products of glaciation yet relatively little is known about how the dynamics of ice flow and glacial erosion interact to give rise to such landforms by linking a finite element model for ice flow through a glacier cross section with an erosion model it is possible to investigate the development of one of the most striking glacial landforms the u shaped valley in addition to providing a detailed understanding of landform development such modeling provides a way to test current understanding of the controls on glacial sliding and erosion to simulate valley development i first model flow through an initial glacier cross section and calculate the glaciological parameters that govern erosion i then numerically simulate erosion to produce a modified transverse profile for which a new flow field and erosion pattern are computed a number of iterations permits examination of the progressive transformation of cross section form which can be compared with field data model predictions of the cross section flow field are in close accord with data from the athabasca glacier and include marked lateral variations in sliding velocity with an erosion law dependent on basal velocity the model predicts the rapid transformation of a v shaped cross section into a recognizably glacial form over a time period on the order of 10 4 yr and the eventual development of a steady state quasi parabolic glacier cross section better agreement with empirical data from glaciated valleys is obtained by including temporal variations in ice discharge in order to mimic the characteristics of 100 000 yr glacial cycles the high discharge phase dominates form development and at low discharges cross section form is essentially inherited from the central part of the form that developed during the preceding high discharge phase

bakken madison petroleum systems in the canadian williston basin part 2 molecular markers diagnostic of bakken and lodgepole source rocks abstract the uppermost devonian mississippian bakken formation black shale and the mississippian lodgepole formation carbonate represent two of the most important source rocks in the canadian williston basin quantitative analyses of both saturated and aromatic hydrocarbon fractions reveal significant differences in the relative distributions and absolute concentrations for a wide range of molecular markers between the extracts of the two source units among others the bakken shales are characterized by their high relative abundance of trimethyl aryl and diaryl isoprenoids likely derived from green sulfur bacteria chlorobiaceae in contrast the lodgepole carbonates at similar maturity levels display a c35 homohopane prominence and abundant benzohopanes ring d monoaromatic 8 14 secohopanes and a tetracyclic monoaromatic hydrocarbon the distinctive nature of molecular marker fingerprints diagnostic of the two source rocks is clearly related to their different organic inputs and depositional environments additionally the large difference in the absolute concentrations of these compounds observed in both source units may potentially lead to biased geochemical interpretations if strictly conventional saturate based biomarker approaches were used for oil oil and oil source correlation

quaternary glaciations recorded by glacial and fluvial landforms in the shaluli mountains southeastern tibetan plateau abstract the shaluli mountains a tectonically controlled mountain range between the jinsha and yalong river rifts are located in southeastern tibetan plateau in the central shaluli mountains an ice cap of 3600 km 2 once developed on the haizi shan abundant glacial landforms are present on the haizi shan and in the surrounding river valleys together with the outwash terraces in the yazheku river the northeastern part of the haizi shan provides an ideal site to examine the quaternary glacial history of the region sedimentological and morphostratigraphical analysis field mapping and dating by electron spin resonance esr define at least seven major glacier advances in the haizi shan area six major glacier advances likely occurred during marine oxygen isotope stage mis 16 mis 14 12 mis 6 mis 3 early mis 2 and the global last glacial maximum these can be defined on the basis of esr dating and stratigraphical analysis of the glacial landforms in front of the kuzhaori glacial trough on the southern slope of the haizi shan the outwash terraces in the yazheku river also record four major glacier advances which occurred during mis 16 mis 12 mis 6 and mis 2 in addition the moraines preserved on the southwestern part of the haizi shan suggest that a glacial advance likely occurring during the lateglacial the extent of glaciation on the haizi shan decreased with time

an uncertainty approach to estimate recoverable reserves from the bakken petroleum system in the north dakota part of the williston basin instead of using discrete values for properties that influence the volumetric calculation for recoverable reserves from the middle bakken pronghorn and three forks reservoir rocks in the williston basin in north dakota an uncertainty based assessment method was used various estimates have been published in the past that attempt to quantify recoverable reserves from the bakken petroleum system the bakken three forks trend is regarded as an unconventional tight oil play typical of a continuous type basin centered accumulation however production data reveal that areas are unequal and that certain regions stand out as sweet spots whereas others exhibit fairly high water cuts this paper is based on 28 well models which have been porosity calibrated and adjusted for the prevalent thermal regime the area of interest was delineated by geological parameters such as shale maturity and reservoir rock presence as well as existing production data the purpose of this study is to use an uncertainty assessment method based on hundreds of basin model simulations that sample ranges of probable input parameters to quantify the recoverable reserves from the bakken petroleum system in north dakota the results are displayed in reverse cumulative probability plots tornado sensitivity charts as well as in maps of the 10 chance 50 chance p50 90 chance values this means that there is an x chance of success or an x probablity of realizing a certain amount of hydrocarbon the p50 results of the uncertainty assessment indicate that approximately 4 billion bbl of oil and 3 6 tcf 102 billion m3 of gas are recoverable from the middle bakken pronghorn and three forks reservoir rocks in north dakota the bakken three forks trend appears to be an overcharged petroleum system where the available pore space in reservoir rocks is the limiting factor for each accumulation

millennial scale ice rafting events and hudson strait heinrich like events during the late pliocene and pleistocene a review abstract various types of abrupt millennial scale climate variability such as dansgaard oeschger and heinrich events characterized the last glacial period over the last decade a number of studies demonstrated that such millennial scale climate variability was not limited to the last glacial but inherent to quaternary climate here we review the occurrence and origin of millennial ice rafting events in the north atlantic during the late pliocene and pleistocene last 3 4 ma with a special focus on north atlantic hudson strait hs heinrich like events we show that heinrich layers 5 4 2 and 1 in marine sediment cores from across the north atlantic all bear the organic geochemical fingerprint of the hudson area using this framework and combining previously published results detailed investigations into the organic and inorganic chemistry of ice rafted debris ird found across the north atlantic demonstrate that prior to mis 16 650 ka ird in the north atlantic did not originate from the hudson area of northern canada the signature of this early ird is distinctly different compared to that of hs heinrich layers rather ice rafting events during the late pliocene and early pleistocene predominantly emanated from the calving of the greenland and fennoscandian ice sheets and possibly minor contributions from local ice streams from the north american and british ice sheets compared to north atlantic hs heinrich events these early pleistocene ird events had a limited impact on surface water characteristics in the north atlantic north atlantic hs heinrich like events first occurred during mis 16 at the same time the dominant frequency in silicate rich ird accumulation shifted from the obliquity 41 ka to a 100 ka frequency across the north atlantic iceberg survivability or a change in iceberg trajectory likely did not control this change in ird regime these results lend further support for the existing hypothesis that an increase in size thickness of the laurentide ice sheet controls the occurrence of north atlantic hs heinrich events favoring an internal dynamic mechanism for their occurrence

evaluating the timing of former glacier expansions in the tian shan a key step towards robust spatial correlations the timing of past glaciation across the tian shan provides a proxy for past climate change in this critical area correlating glacial stages across the region is difficult but cosmogenic exposure

ams radiocarbon dating of late quaternary glacial landforms source of the urumqi river tien shan a pilot study of 14c dating on inorganic carbon abstract carbonate coatings on roche moutonnees and till clasts and calcite in the fine matrix of late quaternary glacial landforms were dated by using accelerating mass spectrometry ams radiocarbon dating at the source area of the urumqi river tien shan the values of 13 c and the sedimentary properties of tills and coatings show that the precipitation of inorganic carbon in calcite in the till matrix is synchronous with till formation the carbon dating of the fine matrix of till and the coatings on till clasts can be used to determine or estimate the ages of glacial moraines as the inorganic carbon in fine matrix and coatings may preserve well with no or little fractionation the largest scaled moraine near wangfeng road maintenance station was dated to be 19 23 ka the age of the local last glaciation maximum was therefore coincident with the global last glaciation maximum the moraine at glacier observatory which was formerly believed to be the product of neoglaciation seems to be the relics of a lateral moraine also formed during the last glaciation

esr dating studies of palaeo debris flow deposits in dongchuan yunnan province china abstract the ages of palaeo debris flow deposits in dongchuan yunnan province were determined by esr dating they are consistent with a 14 c age estimate the results suggest that the debris flow deposits were formed during humid periods of the late pleistocene simulation experiments and sem analysis show that the resetting of ge centres in quartz is most likely due to collisions of the quartz grains during the process of rapid deposition

esr dating of glacial tills and glaciations in the urumqi river headwaters tianshan mountains china abstract electron spin resonance esr dating of the shangwangfeng the xiawangfeng and the gaowangfeng tills in the headwaters of the urumqi river was carried out using ge centers in quartz grains the shangwangfeng till is dated at 35 3 5 ka bp three dates from the lower portion of the xiawangfeng till are 171 1 17 176 18 and 184 7 18 ka bp respectively and the age of the gaowangfeng till is 459 7 46 ka bp considering the available ages i e 14 c tl and esr and the principles of geomorphology and stratigraphy the shangwangfeng till is determined to be deposited in marine isotopic stage 2 3 mis2 3 the upper part of the xiawangfeng till was formed in mis4 and the lower part was deposited in mis6 the gaowangfang till is the oldest at the head of the urumqi river corresponding to mis12 the age of the gaowangfang till also demonstrates that the tianshan mountains lay at a suitable altitude for a glacial climate at that time when the glaciers on this segment of the mountain began to develop

a preliminary study on timing of the oldest pleistocene glaciation in qinghai tibetan plateau abstract the qinghai tibetan plateau consists of broad planation surfaces basins and mountain ranges research in the past several decades has argued that quaternary glaciations developed only around the high mountains on the plateau not the whole plateau surface in recent years we and other researchers have dated the oldest moraines in several mountain ranges using esr the relative age of these moraines was first confirmed based on their geomorphological position and degree of weathering the results show that the oldest glaciation the zhonglianggan glaciation in the qilian mountains occurred at about 463 ka and the high elevation moraines of the wangfeng glaciation the oldest ones in the tianshan mountains was dated at 477 and 460 ka the oldest glaciation in the hengduan mountains the daocheng glaciation which is characterized by moraines with deeply weathered red soils was dated at 570 ka this is reconfirmed by an age of 590 ka on the oldest moraine at yulong shan in the southern hengduan mountains the wangkun glaciation the oldest in the kunlun shan pass was dated at 710 ka using esr this is similar to the 36cl age of the bottom ice layer of a 309 m ice core of guliya ice cap western kunlun shan these dates of the oldest moraines in several mountain ranges suggest that glaciers began to develop during mis 12 in the qilian and tianshan mountains mis 16 in the hengduan mountains and perhaps mis 18 in the kunlun and nyainqentanglha mountains a widespread rapid uplift of qinghai tibetan plateau kunlun huanghe tectonic movement was determined to have occurred between 1 1 and 0 6 ma thus it is reasonable that uplift of mountain ranges on the tibetan plateau during this time initiated widespread mountain glaciations in ice ages

faulting controls on oil and gas composition in the yingmai 2 oilfield tarim basin nw china abstract the accumulation mechanism of hydrocarbons in the yingmai 2 oilfield of the tabei uplift in the tarim basin is not well understood here the characteristics and formation of paleozoic faults in the yingmai 2 oilfield are studied with new 3d seismic data and regional geologic data inclusion features and geochemical parameters are used to investigate the faults controlling the oil and gas compositions the results indicate that three fault systems developed in the yingmai 2 oilfield a nnw trending strike slip fault system that formed in the middle caledonian a nw trending strike slip fault system that formed in the caledonian late hercynian and a ne trending thrust fault system that formed in the late hercynian indosinian which was associated with volcanic activity the two strike slip fault systems were important early hydrocarbon migration pathways in the late caledonian early hercynian late hercynian and himalayan accumulation periods the ne trending thrust faults were sealed by volcanics and divided the originally uniform oilfield into two accumulation systems during the himalayan this finding is supported by the differences in the compositions of the oils and gases in the eastern ym area and the western yg area yingmai 2 oilfield the oil density ic4 nc4 ph nc18 and v ni ratios of the oils in the reservoirs in the ym area are lower than those in the yg area whereas the tmnr temnr 4 1 dbt pr ph c29 diasterane c29 regular sterane ratios h2s content and the content of himalayan hydrocarbon inclusions are higher the hydrocarbon accumulation in the yingmai 2 oilfield is attributed to multiple episodes of hydrocarbon charging and suggests that the ym area has greater exploration potential than the yg area

geochemistry of petroleum systems in the eastern pearl river mouth basin evidence for mixed oils abstract detailed analyses of crude oils and source rock extracts indicate the presence of two effective petroleum source rocks in the eastern pearl river mouth basin of the south china sea region oils derived from the lacustrine source rocks in the eocene wenchang formation are characterized by abundant c 30 4 methyl steranes with relatively few c 19 tricyclic terpane and bicadinanes in contrast oils from the eocene oligocene enping formation source typically contain significant amounts of c 19 tricyclic terpane and bicadinanes with relatively few 4 methyl steranes and high pristane phytane ratios however the chemical compositions of a large number of oils do not conform to those of the unknown source rocks consistent with mixing of the two sources mixed oils occur mainly in the huizhou sag and along its south margin and the highest proportion of the enping formation source in the reservoired mixed oils is estimated to be around 80 laboratory mixing experiments using selected end member oils indicate that even with 50 80 contribution from the enping formation source the mixtures still display sterane biomarker ratio signatures diagnostic of the wenchang formation source therefore the presence of abundant 4 methyl steranes is a necessary but not sufficient indicator for the wenchang formation source in the eastern pearl river mouth basin although our results support the wenchang formation as a major source to the known oil discoveries in the study area the contribution of the enping formation source to traps in the huizhou sag and surrounding area cannot be ignored there is clear evidence for the recharge of enping formation derived oils into early biodegraded oil accumulations to form light oil accumulations

mississippian bakken and equivalent formations as source rocks in the western canadian basin abstract the organic rich bakken formation of mississippian age has previously been identified as the source rock for mississippian reservoired oils in the williston basin north dakota examination of c15 hydrocarbon data including biomarker distributions steranes triterpanes and diterpanes and stable carbon isotope ratios of bakken formation core samples from williston basin and those of equivalent formations from western canadian basin alberta reveals similar types of extractable organic matter stable carbon isotope and biomarker data support strong positive correlations between the bakken formation core samples and mississippian oils from both basins in addition a positive correlation is found between bakken core samples and lower cretaceous heavy oil deposits from athabasca cold lake and peace river areas in alberta thus the mississippian bakken and equivalent formations are also important source rocks in the western canadian basin

glacial advances in southeastern tibet during late quaternary and their implications for climatic changes southeastern tibet is the type area for monsoonal maritime glaciers in the qinghai tibet plateau with more than 4000 mountain glaciers covering an area of approximately 8000 km 2 based on moraines in the boduizangbo river valley glacial advances have been recognized for the guxiang baiyu and yuren glaciations cosmogenic radionuclide surface exposure esr and radiocarbon dating methods are used to estimate moraine ages the dates suggest that glacial advances occurred during mis 6 mis 2 and mis 1 moraines of possible mis 4 or mis 3 age are also present but have not yet been dated during the guxiang glaciation glaciers converged in the boduizangbo valley and formed a glacier approximately 100 km long reaching the parlongzangbo river valley during the baiyu glaciation the glacier was about 80 km long yet did not reach the main valley of the parlongzangbo river during the yuren glaciation glaciers advanced only within tributary valleys feeding the boduizangbo river based on glacier extent reconstructed equilibrium line altitudes during the guxiang and baiyu glaciations were approximately 800 m and 600 m lower respectively than at present mean annual air temperatures were depressed by approximately 6 6 7 8 c compared to present values estimating a 40 decrease in precipitation during

quaternary glacial chronology of the ateaoyinake river valley tianshan mountains china abstract the ateaoyinake river originates on the southern slope of the tumur peak the largest center of modern glaciation in the central tianshan mountains in china six sets of moraines and associated glacial sediments are well preserved in the ateaoyinake river drainage recording a complex history of quaternary glacial cycles and landscape evolution dating the landforms allow the temporal and spatial shifts of past cryosphere and climate to be determined dating of the tills and outwashes was undertaken with electron spin resonance esr and optically stimulated luminescence osl two osl ages date outwash and till to 7 3 0 8 ka and 12 3 1 2 ka respectively the esr ages date six sets of moraines to 3 4 ka 14 27 ka 40 54 ka 55 62 ka 134 4 12 6 ka and 219 7 20 5 ka 440 6 41 7 ka if these are correct ages of deposition they suggest that glaciers advanced during the neoglacial and during marine oxygen isotope stages mis 2 3b 4 6 and 12 the mis 3b moraine was created by a glacier nearly as large as or possibly larger than those of the global last glacial maximum of mis 2 the oldest till belongs to the qingshantou glacial stage its single age is consistent with two published esr ages 459 7 46 and 471 1 ka from the gaowangfeng till near the headwaters of the urumqi river in the eastern tianshan mountains these dates suggest that the central and the eastern segments of the tianshan mountains were high enough to be glaciated by mis 12 the geochronology of the glacial landforms in this valley is the first step towards understanding glacial and landscape evolution in this region furthermore this geochronology and previously published geochronology near the headwaters of the urumqi river provide a temporal framework for examining the rates of landscape evolution in the glaciated regions of the tianshan mountains

marine oil source of the yingmaili oilfield in the tarim basin abstract although a large amount of petroleum has been discovered in the tarim basin the origin of the oils is still disputed yingmaili oilfield was selected as a case study to further examine hydrocarbon generation and accumulation in the basin detailed geochemical studies were conducted to unravel the formation mechanisms the oils in the field correlate well with middle upper ordovician o 2 3 rocks or similar rocks oil oil and oil source rock correlation by maturity parameters of saturate and aromatic hydrocarbons suggest that the yingmaili and adjacent oils are primarily comparable to source rocks deeper than 6000 m the results also showed that carbonates might be important potential source rocks as indicated by a relatively high abundance of aromatic sulfur compounds and relatively high c 29 c 30 hopane and c 35 c 34 hopane ratios of the oils which are typical features of carbonate source rocks we suggest the oil from wells yg2 and yg2 1c are more suitable to be end members from the o 2 3 source rocks or similar rocks than the oil from well ym2 as previously suggested we also suggest that the previous model of hydrocarbon migration along the ordovician unconformity should be revised

reconstructing the palaeoecosystem and palaeodepositional environment within the upper devonian lower mississippian bakken formation a biomarker approach abstract biomarkers have been used extensively to correlate oil families oil source rock relationships and source inputs and to help identify the palaeodepositional environment for a given geological sedimentary unit despite their application in characterising the bakken formation shales a number of biomarkers still appear unable to provide us a consistent understanding regarding heterogeneity in source organic matter and palaeoenvironment here we infer the palaeodepositional environment within the bakken formation shales using a biomarker suite and biomarker depth profiles we also use the occurrence and abundance of biomarkers to define organic facies and to make inferences regarding biotic interactions drawn from modern analogues the variations and co occurrence of biomarkers is explained by the existence of a proposed complex algal bacterium bacteriovore palaeoecosystem this approach not only helps explain the depth variation in occurrence and concentration of biomarkers and the molecular composition of associated organic matter but also advances the use of biomarker analysis and biomarker associations to determine a complex environment sensitive palaeoecosystem

current challenges to esr dating abstract electron spin resonance dating is applicable to a wide range of materials found at quaternary sites and which can generally be assured to exhibit zero signals at the time to be dated t 0 local inhomogeneity in external dose rates may contribute to dispersion in apparent dates but average dates may still be good estimates of site ages testing of u uptake models by u series measurements shows that both early and continuous uptake can occur possibly even in the same site problems of signal lifetime determination and diagenesis are reviewed

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

geochemistry of petroleum systems in the niuzhuang south slope of bohai bay basin part 2 evidence for significant contribution of mature source rocks to immature oils in the bamianhe field the chemical compositions of 28 representative crude oils and oil sand samples collected from the bamianhe region of the bohai bay basin eastern china were studied in detail in order to understand their genetic relationships biodegradation ranking and thermal maturity level molecular geochemical parameters indicate the presence of one single oil family in the cenozoic reservoirs a number of biomarker features support deposition of the source rocks for these oils under conditions of enhanced salinity stratified water columns the extremely low maturity levels of these immature oils as indicated by sterane isomerization ratios were not supported by other maturity parameters the genetic relationship between the oils and the es4 and es3 members of the eocene oligocene shahejie formation present in the deeper part of the niuzhuang sag but not those along the niuzhuang south slope was suggested using a wide range of molecular parameters variation in the sterane concentrations observed from potential source rocks with different maturity levels in the study area suggests a high probability of migration contamination of mature oils by immature bitumens along migration pathways or from intra reservoir shales variation in the level of oil biodegradation could also create anomalies in the use of gross oil compositions as an indicator of oil maturity although the recent rapid subsidence of the bohai bay basin and the saline depositional environment of one of the potential source rocks favor oil generation at relatively low maturity levels most of the economic oils discovered in the bamianhe region appear to have derived from conventionally mature source rocks but contain lower maturity fluids admixed with them

unusual polycyclic alkanes in lower cretaceous ostracode sediments and related oils of the western canada sedimentary basin several series of unusual polycyclic alkanes ranging from tricyclic to heptacyclic have been identified as major components in extracts of lower cretaceous ostracode zone sediments of the western canada sedimentary basin these compounds appear to be specific markers for the ostracode zone sourced oils in the lower mannville group reservoirs of the provost area and may represent a new class of molecules whose natural distribution and biological significance remains to be determined the stable carbon isotopic data of the tri tetra and pentacyclic alkanes appear to be related to pristane and phytane yet the significant isotopic depletion observed in the hexacyclic compounds suggests that they may be derived from different groups of organisms or different biosynthetic routes

holocene sea levels and palaeoenvironments malay thai peninsula southeast asia sedimentological and palynological investigations of great songkhla lakes east coast of the malay thai peninsula southeast asia reveal sedimentary sequences rich in palynomorph assemblages dominated by pollen of mangroves and freshwater swamps compared with other regions in southeast asia the assemblages are of relatively low diversity geochronological data indicate that the great songkhla lakes record one of the earliest mangrove environments in southeast asia 8420 8190 cal yr bp which are subsequently replaced by a freshwater swamp at 7880 7680 cal yr bp owing to the decline of marine influence sea level observations from great songkhla lakes and other areas of the malay thai peninsula reveal an upward trend of holocene relative sea level from a minimum of 22 m at 9700 9250 cal yr bp to a mid holocene high stand of 4850 4450 cal yr bp which equates to a rise of c 5 5 mm yr the sea level fall from the high stand is steady at c 1 1 mm yr geophysical modelling shows that hydroisostasy

esr dating of the sediments of the last glaciation at the source area of the urumqi river tian shan mountains china abstract electron spin resonance esr dates were obtained from glacial quartz sands formed during the last glaciation at the source area of the urumqi river tian shan mountains northwestern china esr dating of a basal till interpreted as a subglacial melt out till deposited in an end moraine which was produced in the late stage of the last glaciation is consistent with ages determined through the ams 14c method however dating of the overlying sediment interpreted as supraglacial melt out till associated with the same moraine produced a result that differs from that determined using the ams 14c method subglacial comminution could reset the esr signal thus making esr dating of basal till possible the lower wangfeng group formerly of controversial age was formed ca 50 70 ka during the early stage of the last glaciation it was deposited throughout the main valley as low as 2300 m a s l over a length in excess of 19 km fluvial sandy gravel was deposited in the interstadial between the early and late stages of the last glaciation

redox and paleoenvironmental conditions of the devonian carboniferous sappington formation southwestern montana and comparison to the bakken formation williston basin abstract the sappington formation outcrops in southwestern montana and spans the upper devonian lower mississippian transition it consists of two carbonaceous shale intervals one upper and one lower and a middle dolomitic siltstone and silty sandstone it was deposited in a relatively small basin with the central montana uplift separating the sappington basin from the williston basin to the east which contains the economically important bakken formation previous biostratigraphic and lithostratigraphic comparisons have identified the sappington and bakken formations as depositionally contemporaneous and due to the subsurface nature of the bakken the sappington has emerged as a useful outcrop analogue this study presents new geochemical data from the sappington formation providing a comparison to the bakken and insight into paleo redox conditions during the devonian carboniferous on the western laurentian margin geochemical signals in the sappington formation outcrop samples are partially obscured by oxidative weathering but similar to the lower bakken shale the lower sappington shale appears to record dominantly euxinic conditions albeit with intervals when the water column was suboxic to ferruginous and with an absence of organic or inorganic geochemical evidence for photic zone euxinia the upper sappington shale appears to have been deposited in ferruginous to dysoxic conditions thus the sappington appears to be an excellent analogue to the bakken on a lithostratigraphic level but the geochemical environment for black shales source rock deposition appears less reducing closer proximity to the open ocean and consequent lower levels of restriction may have been responsible for these redox differences however sappington core samples and an increased focus on integrating geochemical data into the regional stratigraphic record will be necessary to further understand paleoceanographic and biogeochemical drivers

hydrocarbon biomarkers thermal maturity and depositional setting of tasmanite oil shales from tasmania australia this study represents the first geological and organic geochemical investigation of samples of tasmanite oil shale representing different thermal maturities from three separate locations in tasmania australia the most abundant aliphatic hydrocarbon in the immature oil shale from latrobe is a c19 tricyclic alkane whereas in the more mature samples from oonah and douglas river low molecular weight n alkanes dominate the extractable hydrocarbon distribution the aromatic hydrocarbons are predominantly derivatives of tricyclic compounds with 1 2 8 trimethylphenanthrene increasing in relative abundance with increasing maturity geological and geochemical evidence suggests that the sediments were deposited in a marine environment of high latitude with associated cold waters and seasonal seaice it is proposed that the organism contributing the bulk of the kerogen tasmanites occupied an environmental niche similar to that of modern sea ice diatoms and that bloom conditions coupled with physical isolation from atmospheric co2 led to the distinctive isotopically heavy 13c values 13 5 to 11 7 for the kerogen 13c data from modern sea ice diatoms 7 supports this hypothesis isotopic analysis of n alkanes in the bitumen 13 5 to 31 suggest a multiple source from bacteria and algae on the other hand the n alkanes generated from closed system pyrolysis of the kerogen 15 are mainly derived from the preserved tasmanites biopolymer algaenan the tricyclic compounds mean 8 both in the bitumen and pyrolysate have a common precursor they are consistently enriched in 13c compared with the kerogen and probably have a different source from the n alkanes the identification of a location where the maturity of the tasmanite oil shale approaches the oil window raises the possibility that it may be a viable petroleum source rock

unusual carbon isotope compositions of biomarker hydrocarbons in a permian tasmanite abstract the permian oil shale sample of this study is from a deposit in tasmania in which the only recognizable structures are large thick walled unicellular specimens of the green alga tasmanites the fossils are so densely packed that this shale is termed tasmanite the carbon isotopic composition of bulk kerogen carbon c 13 c org 16 6 vs pdb is unusually enriched in 13 c compared to marine permian organic carbon 25 to 30 this 13 c enrichment suggests specific environmental conditions co 2 draw down and or physiological specialties cell size and growth rate of tasmanites which in modern environments are known to cause 13 c enrichment in marine phytoplankton isotope signatures of extractable organic species unlike in normal immature oil shales are considerably enriched in 13 c compared to the kerogen the bitumen 10 9 is composed predominantly of extended saturated c 18 c 25 tricyclic terpane hydrocarbons 9 9 to 12 2 total range with an average of 10 8 these tricyclics are not only found as free lipids in the extract but also in pyrolysates with similar isotopic signatures and are therefore likely biosynthesis products of tasmanites the monoaromatic and diaromatic tricyclic terpane hydrocarbons c 17 c 19 have similar isotopic signatures 9 3 to 12 8 total range with an average of 10 6 two monoaromatic tetracyclic hydrocarbons c 23 and c 24 a quantitatively minor but biogenetically interesting group average at 10 2 in contrast pristane and phytane as well as n alkanes 18 to 22 are depleted in 13 c compared to kerogen carbon the isotopic similarity of all the cyclic terpanes in this sample together with their occurrence in the free lipids and kerogen suggests that they have a common origin and are biosynthesis products of the marine unicellular green algae tasmanites the tetracyclic terpanes therefore are not des a oleananes derived from land plants but are possibly monoaromatic des a gammaceranes or other des a triterpenoids derived from marine sources the unusual enrichment in 13 c in the cyclic hydrocarbons is hypothesized to result from the special growth conditions of the algae isoprenoids and n alkanes are also likely biosynthesis products of tasmanites possibly during the spore formation stage when physiological and environmental conditions were different than during planktonic biosynthesis

correlating rock eval tmax with bitumen reflectance from organic petrology in the bakken formation abstract the bakken formation is a major unconventional shale play in north america which lacks an independent calibration for accurately correlate thermal maturity from programmed pyrolysis via temperature of maximum pyrolysis yield tmax with optical methods e g bitumen reflectance in the present study several samples from the upper and lower members of the bakken formation in north dakota were analyzed by detailed organic petrography bitumen reflectance and rock eval 6 pyrolysis organic petrography showed that the organic matter consists of various types of bitumen amorphous matrix bituminite liptodetrinite acanthomorphic acritarch marine alginite granular micrinite and inertinite macerals fluorescence color under uv light of macerals from the liptinite group was used to confirm the thermal maturity level due to the scarcity absence of primary vitrinite ro measurements on solid bitumen particles were converted to equivalent vitrinite reflectance vro eq using a published correlation equation from the coeval new albany shale overall geochemical analysis from rock eval pyrolysis reveals almost similar trends for the upper and lower members which allowed proposing a single correlation for vro eq to tmax for the bakken shale comparing the observed relationship for the bakken shale with the previously established models for the devonian duvernay shale canada and the mississippian barnett shale united states shows discrepancies results confirmed the necessity of developing a specific equation for the bakken shale members to relate vitrinite and solid bitumen reflectance data to tmax from rock eval pyrolysis furthermore the outcome of this study indicated that linear trends cannot accurately represent the relationship between these two parameters considering the kerogen kinetics and non linear relationship between transformation ratio tr and tmax therefore a polynomial correlation a better fit to the data was proposed to more accurately represent the nature of this relationship

bakken madison petroleum systems in the canadian williston basin part 1 c21 c26 20 n alkylpregnanes and their triaromatic analogs as indicators for upper devonian mississippian epicontinental black shale derived oils abstract a series of 20 n alkylpregnanes and their triaromatic analogs have been tentatively identified in crude oils and source rock extracts from the western canada sedimentary basin when found in oils in this basin these compounds may serve as molecular indicators for source input from the uppermost devonian mississippian epicontinental black shales crown copyright

apatite u th he signal of large magnitude accelerated glacial erosion southwest british columbia alpine glaciers are efficient agents of erosion and capable of significantly modifying topography despite recent advances in theoretical and field studies that quantify glacial erosion processes few studies have documented glacial erosion rates over long 10 6 yr or large more than tens of kilometers scales we use apatite u th he ahe and apatite fission track aft cooling ages to address the late miocene to holocene erosion history across two 60 km long transects of the heavily glaciated southern coast mountains british columbia observed ahe cooling ages from equal elevation samples range between 1 5 and 8 ma and suggest that thick alpine glaciers resulted in a 16 km shift of the highest point in the topography in the past 1 5 4 0 m y we evaluated temporal and spatial variations in erosion rates using a three dimensional thermal kinematic model that predicted ahe and aft ages at the surface for different erosion histories comparison of model predicted and observed cooling ages suggests an increase in erosion rates of as much as 300 over the past 1 5 7 m y coincident with the onset of glaciation of this range

electron spin resonance esr dating abstract esr dating has been systematically applied in earth sciences and archaeology since 1975 when ikeya dated a stalactite from the akiyoshi cave in japan in the meantime this new technique has been successfully applied to the dating of materials such as speleothems spring deposited travertines mollusc shells corals and tooth enamel the present research focuses on the dating of quartz which allows the age assessment of heated ceramics volcanic rocks intrafault material or windblown sediments esr dating is based on the measurement of the number of paramagnetic centers in a mineral these centers are generated by alpha beta and gamma radiation of the matural radioelements such as u th and k and have accumulated over time two parameters have to be determined the accumulated dose ad and the dose rate d to which the sample was exposed this review comprises three major parts a introduction into esr dating b application of the method and c appendices giving detailed description of dose rate calculation physical basis of electron spin resonance the esr spectrometer and esr lines the major emphasis lies on the outline of the application of esr dating this includes the discussion of the esr signals of the various materials sampling sample preparation and measurement techniques

oil prone alginite macerals from organic rich mesozoic and palaeozoic strata saskatchewan canada abstract hydrogen rich oil prone remnants of algae or alginite macerals are examined from organic rich carbonate and siliciclastic phanerozoic intervals at saskatchewan canada using incident light fluorescence microscopy upper cambrian alginites from siliciclastic rocks contribute to types ii iii kerogen as defined by rock eval pyrolysis and consist mainly of unicellular prasinophyte leiosphaeridia unique agglomerations of synsphaeridium sphaeromorphs and two types of coccoidal gloeocapsomorpha alginite middle ordovician platform to basin shales host mainly disseminated gloeocapsomorpha prisca alginite macerals types i ii kerogen upper ordovician platformal carbonates contain disseminated and stromatolitic varieties of g prisca alginite type i kerogen with the latter occasionally forming wholly organic well preserved microtextures concentrations of nostocaceae like filamentous alginite type ii kerogen occur locally in upper ordovician carbonates and form unique brecciated and crinkled stromatolites middle devonian type ii kerogen rich intervals from a platform setting are dominated by stromatolitic nodularia like filamentous alginite whereas abundant leiosphaeridia and tasmanites alginite characterize inter reef basinal palaeoenvironments middle and upper devonian organic rich intervals associated with evaporites contain mainly stromatolitic filamentous alginite with only minor amounts of prasinophyte alginite black shales of devonian mississippian age contain abundant leiosphaeridia and tasmanites alginites within a type ii amorphous kerogen network the smallest leiosphaeridia occur in inner shelf rocks whereas the largest forms characterize outer shelf to basin devonian mississippian shales mesozoic marine marls and shales contain prasinophyte alginite dominated by small unnamed sphaeromorphs leiosphaeridia tasmanites and minor pterosphaeridia types ii iii kerogen fresh to brackish water colonial botryococcus alginite as part of a type ii kerogen occurs initially in mesozoic strata deposited in nearshore palaeoenvironments

algal bloom episodes and the formation of bituminite and micrinite in hydrocarbon source rocks evidence from the devonian and mississippian northern williston basin canada organic petrology incident light microscopy of middle devonian inter reef laminates and devonian mississippian epicontinental black shales williston basin canada indicates that algal bloom episodes and consequential bacterial activity played a significant role in the accumulation of amorphous bituminite iii rich organic microfacies corpohuminite like algal akinete cells produced by filamentous algae during algal bloom periods are persistent maceral inclusions within the potential hydrocarbon source rock intervals these cells ro mean range 0 24 0 90 are regarded as positive indicators of stressful palaeoenvironmental conditions unicellular tasmanites and leiosphaeridia marine alginite and variably degraded alginite remnants ghosts within the amorphous kerogen may be products of cell lysis photo oxidation and microbial alteration these processes are characteristic of algal bloom periods minute ca 1 m spheroidal and coccoidal bacteria like macerals are dispersed throughout the bituminite iii network attesting to the importance of microbial activity within the water column and sediment during and after organic matter accumulation dispersed granules laminations and replacement textures of micrinite like macerals within bituminite iii are interpreted as remnants of microbial alteration rather than a residual product of thermal maturation and hydrocarbon generation

spatial variation of bakken or lodgepole oils in the canadian williston basin there are two opposing schools of thought that infer either the bakken formation or the lodgepole formation as the primary source rock for the madison reservoired oils in the canadian williston basin a recent geochemical study revealed evidence indicating the existence of significant mixing of bakken and lodgepole oils in the madison reservoirs to investigate the geographic distribution of the oil compositions we employed a multivariate statistical method to extract source and maturity specific geochemical signatures from a geochemical data set for spatial analysis oil mixing appears to be geographically dependent and restricted by a northeast southwest striking zone torquay rocanville trend in southeast saskatchewan thus fracture or fault systems are inferred to have provided high permeability zones allowing bakken derived oil to migrate upward across the lodgepole formation the areas without significant fault or fracture systems favor lateral oil migration along porous beds restricting bakken derived oil accumulation to pools in bakken reservoirs and lodgepole derived oils to occur primarily in overlying reservoir beds of the madison group

definition and characterization of petroleum compositional families in williston basin north america using principal component analysis abstract petroleum hydrocarbons in the gasoline range grh and saturate sfh 210 c boiling point fractions carry information that is often obscured by compositional diversity and multiple processes working simultaneously multivariate statistical methods can enhance the analysis and interpretation of compositional data from these fractions especially in conjunction with independent geological information in the present study principal component analysis pca was applied to the grh and sfh data for 171 oil samples from the williston basin these oils were previously classified using polycyclic terpane and sterane biomarker traits our results indicate that only family a oils can be uniquely classified using pca families b c and d oils show grh and sfh characteristic compositions consistent with biomarker defined families but these characteristics are insufficient for independent classification however the pca analyses of the grh and sfh compositional traits proves to be a useful technique in recognizing the effect of mixing of oils derived from different sources

organic carbon in bakken formation united states portion of williston basin the upper and lower members of the mississippian and devonian bakken formation in the united states portion of the williston basin are black shales that are extremely rich in organic matter and are the source of much of the oil found in the basin organic carbon values are calculated from formation density logs using the equation toc 154 497 rgr 57 261 where toc is organic carbon content wt and rgr is formation density g cm3 test calculations comparing this equation to laboratory organic carbon analyses from 39 wells in north dakota show an average absolute difference of 1 1 in organic carbon content organic carbon content calculated at 159 locations in north dakota and 107 in montana averages 12 1 for the upper member of the bakken formation and 11 5 for the lower member there is a regional depletion of organic carbon paralleling present day isotherms that reflects the conversion of organic matter to oil and subsequent expulsion of the oil from the formation the mass of organic carbon in the bakken formation is approximately evenly divided between the upper and lower members and it totals about 126 1012 kg in the study area of which 102 1012 kg are in the thermally mature region the assumption that 167 mg hc g toc have migrated out of the mature bakken shales leads to a tentative estimate that hydrocarbons equivalent to 132 billion bbl of 43 api gravity oil have been expelled from the united states portion of the upper and lower members of the bakken formation

hydrogen isotopic compositions of individual alkanes as a new approach to petroleum correlation case studies from the western canada sedimentary basin isotopic compositions of carbon bound hydrogen in individual n alkanes and acyclic isoprenoid alkanes from a number of crude oil samples were measured using gas chromatography thermal conversion isotope ratio mass spectrometry the precision of this technique is better than 3 for most alkanes compared to the large range of d variation among the samples up to 160 the oils were selected from major genetic oil families in the western canada sedimentary basin with source rocks ranging in age from ordovician and possibly cambrian to cretaceous the hydrogen isotopic composition of alkanes in crude oils is controlled by three factors isotopic compositions of biosynthetic precursors source water d values and postdepositional processes the inherited difference in the lipid s biosynthetic origins and or pathways is reflected by a small hydrogen isotopic variability within n alkanes but much larger differences in the d values between n alkanes and pristane phytane the shift toward lighter hydrogen isotopic compositions from paleozoic to upper cretaceous oils in the wcsb reflects a special depositional setting and or a minor contribution of terrestrial organic matter the strong influence of source water d values is demonstrated by the distinctively lower d values of lacustrine oils than marine oils and also by the high values for oils with source rocks deposited in evaporative environments thermal maturation may alter the d values of the alkanes in the oil to some extent but secondary oil migration does not appear to have had any significant impact the fact that oils derived from source rocks that could be of cambrian age still retain a strong signature of the hydrogen isotopic compositions of source organic matter and source water indicates that d values are very useful for oil source correlation and for paleoenvironmental reconstructions

occurrences and distributions of branched alkylbenzenes in the dongsheng sedimentary uranium ore deposits china abstract a series of branched alkylbenzene ranging from c15 to c19 with several isomers 2 5 at each carbon number were identified in sediments from the dongsheng sedimentary uranium ore deposits ordos basin china the distribution patterns of the branched alkylbenzenes show significant differences in the sample extracts the branched alkylbenzenes from organic rich argillites and coals range from c15 to c19 homologues in which the c17 or c18 dominated on the other hand the c19 branched alkylbenzenes dominated in the sandstone siltstone extracts the obvious differences of the branched alkylbenzene distributions between the uranium host sandstones siltstones and the interbedded barren organic rich mudstones coals probably indicate their potential use as biological markers associated with particular depositional environments and or maturity diagenetic processes possible origins for these branched alkylbenzenes include interaction of simple aromatic compounds with or cyclization and aromatization reactions of these linear lipid precursors such as fatty acids methyl alkanoates wax esters or alkanes alkenes that occur naturally in carbonaceous sediments the possible simple aromatic compounds may include substituted benzenes functionalized compounds such as phenols that are bound to kerogen at the benzyl position and phenols that are decomposition products derived from aquatic and terrestrial sources the distributions of methyl alkanoates and n alkanes were found to be different between organic rich mudstone coal and sandstone siltstone from this result it can be concluded that such differences of the alkylbenzene distributions were mainly resulting from the differences of organic precursors although maturity effect and radiolytic alteration cannot be completely excluded

quaternary glaciation of the bailang river valley qilian shan abstract the qilian shan on the northeast margin of the qinghai tibetan plateau is weakly influenced by the asian monsoon until recently the quaternary glacial geology of this region has been poorly understood this paper describes a sequence of quaternary glacial deposits in the upper reaches of the bailang river using electron spin resonance esr thermoluminescence tl and radiocarbon dating tills loess buried soils and landforms were dated the oldest till was dated 463 ka bp by esr a younger till and its outwash terrace were dated to 135 and 130 ka bp the loess on this outwash terrace was dated to 141 7 11 4 ka bp at its base and 43 7 3 5 ka bp in its central part by tl dating a buried soil on a younger till was dated at 6920 78 ka bp using 14c the glacial landforms and these dating results show that glacial advances occurred during the little ice age the neoglacial mis 2 4 mis 6 and mis 12 glaciation during mis 12 implies that the qilian mountains were rising coevally with the qinghai tibetan plateau and were probably at a sufficient elevation for glaciation since at least 463 ka bp

aryl isoprenoids and diaromatic carotenoids in paleozoic source rocks and oils from the western canada and williston basins abstract aryl isoprenoids in the range c13 c31 have been identified in source rock bitumens and oils from several paleozoic age petroleum systems in the western canada and williston basins the principal compounds possess the 2 alkyl 1 3 4 trimethyl substitution pattern characteristic of diaromatic carotenoids found in the chlorobiaceae family of photosynthetic sulfur bacteria two c40 perhydrodiaromatic carotenoids which are structurally related to the presumed precursors of the aryl isoprenoids have also been identified in oils and source rock bitumens of the duvernay late devonian petroleum system pyrolysis gas chromatograms of kerogens isolated from several paleozoic source rocks show an unusual abundance of 1 2 3 4 tetramethylbenzene it is proposed that this compound arises from cleavage of diaromatic carotenoid moieties which have been incorporated into the kerogen structure with increasing maturation concentrations of the aryl isoprenoids in duvernay source rock bitumens increase to a point whereas the c40 perhydrodiaromatic carotenoids decrease steadily previous studies have suggested that aryl isoprenoids may be indicators of enhanced salinity environments this is not supported by the present work which shows high concentrations in source rocks associated with presumed normal marine salinities there is however a general association with intervals of condensed clastic or mixed clastic carbonate sedimentation within carbonate depositional systems from the association found and from parallels to modern habitats of photosynthetic bacteria it can be inferred that these biomarkers indicate prolific bacterial growth in a stratified water column at and below the oxic anoxic boundary layer in sub tropical to tropical marine environments

petroleum source rocks and stratigraphy of the bakken formation in north dakota the bakken formation devonian and mississippian of north dakota consists of upper and lower black organicrich shales separated by a calcareoh siltstone middle member the formation is a relatively thin unit maximum thickness of 145 ft 44 2 m with the lower shale attaining a maximum thickness of 50 ft 15 2 m and the upper shale a thickness of 23 ft 7 m the shales are hard siliceous pyritic fissile and noncalcareous they contain abundant conodonts and tasmanites and have planar laminations accented by pyrite the upper and lower shales were apparently deposited in an offshore marine anoxic environment where anoxic conditions may have been caused by a stratified water column resulting from restricted circulation organic matter deposited in the black shales was derived mostly from planktonic algae organic geochemical analyses used to evaluate the bakken shales as petroleum source rocks include organic carbon measurements chromatographic analysis of organic extracts pyrolysis vitrinite reflectance and visual kerogen typing the bakken shales are very organicrich average of 11 33 wt organic carbon and contain predominantly amorphous kerogen which is inferred to be sapropelic the onset of hydrocarbon generation occurred at an average depth of 9 ooo ft 2 740 m based on interpreting plots of geochemical parameters with depth e g ratios of hydrocarbon to nonhydrocarbon saturated hydrocarbon to organic carbon pyrolytic hydrocarbon to organic carbon and the pyroiyss production index hydrocarbon content and thermal kerogen breakdown increase greatly in the shales where they are buried more than 9 ooo ft 2 740 m the effective source area of the bakken as determined by maps of the above chemical parameters lies mostly in mckenzie williams dunn and billings counties oil generation in the shales probably began about 75 million years ago late cretaceous time at a temperature of about 100 c and initial expulsion of oil from the bakken probably occurred 70 million years ago late cretaceous time vertical fracture systems located primarily along the nesson anticline antelope oil field and the billings anticline seem to be the most reasonable pathways for migration of oil to occur from the bakken the amount of oil generated by the bakken in north dakota as calculated from pyrolysis data is 92 3 billion barrels of oil if only 10 of this oil was actually expelled from the shales it could easily account for the 3 billion barrels of known type two oil re senes in the williston basin

revelation of organic matter sources and sedimentary environment characteristics for shale gas formation by petrographic analysis of middle jurassic dameigou formation northern qaidam basin china abstract the 7th member of middle jurassic dameigou formation j2d7 in northern qaidam basin china was proposed to have good hydrocarbon generating potential in previous studies here we apply an integrated petrographic and geochemical analysis to investigate the depositional environment real thermal maturity and shale gas potential of organic matter om rich assemblage the relatively high content of c29 regular sterane 56 8 62 8 and vitrinite predominance in maceral composition suggesting plenty of higher plant input combined with the high pristane phytane ratio pr ph 2 8 8 2 and low gammacerane index 0 2 0 4 reveals oxic water column with in situ depositional condition of carbonaceous mudstone when the lower j2d7 was deposited the maceral composition of oil shale at the upper part of j2d7 is mainly amorphous om with small proportion of reworked vitrinite and inertinite consistent with a mainly algea and small amount of exogenous om input when associated with low pr ph 0 8 and high gammacerane index 4 3 the oil shale was deposited in an anoxic saline water column with mainly zooplankton om source the geochemical and petrographic result implies a transitional environment ranging from suboxic semi saline to oxic fresh water environment with varying proportion of higher plant and algae input by in situ deposition and distant transportation for the mudstone at the middle part of j2d7 by use of random reflectance ro distribution two sedimentary environment microcycles which are confirmed by maceral composition from the depth of 1983 m to 1962 m and 1954 m to 1931 9 m are differentiated within the homogenous mudstone section the variation of om input condition and alternation of depositional environment led to accumulation and deposition of various kinds of abundant om when j2d7 was deposited although the om has actually low maturity at oil window with vitrinite reflectance around 0 6 according to the petrographic results the liptinite inherited from higher plants especially suberinite is the main maceral to generate gaseous hydrocarbons at the low maturity which implies that the dameigou formation j2d7 of qaidam basin is of gas potential

esr studies on bleached sedimentary quartz abstract some esr signals in quartz are reported to be bleachable by sunlight and so they promise to be useful for dating sediments grun 1989 the ge signal in quartz is the only one that shows bleaching effects with uv light in short time scales hours therefore we used quartz samples from the sites of mauer homo erectus heidelbergensis samples from a borehole in the neckar valley entensee ladenburg near heidelberg and samples from a pegmatite for basic studies on the ge signal the results show that with our standard sample preparation procedure for quartz separation using red light as for tl samples the natural ge signal is not detectable but rises clearly with gamma irradiation several experiments for examination of the stability and sensitivity of the ge centre in quartz were carried out for comparison with the behaviour of the ge signal we measured the al signal as well our experiments show that the al signal is bleachable in long time scales weeks the behaviour on bleaching irradiation and thermal annealing is very complicated as the al centre is a hole centre it possibly interacts with several electron centres in the quartz and so the processes are of higher order

sulfur isotope ratios in petroleum research and exploration williston basin the three major types of crude oil in the williston basin the type i oils of the winnipeg red river system the type ii oils of the bakken madison system and the type iii oils of the tyler pennsylvanian system can be distinguished by their sulfur isotope compositions they have characteristic dgr34s values of 5 8 1 2 parts per thousand ppt 2 8 0 8 ppt and 4 0 0 7 ppt respectively highly mature oils have less typical values type ii oils which have migrated over a distance of some 150 km beyond the region of generation have maintained their characteristic dgr34s values even though sulfur may have been lost this indicates little or no interaction with reservoir sulfates under normal circumstances on the periphery of the basin type ii oils altered by water washing and biodegradation have altered dgr34s values which increase from 2 9 to 9 4 ppt with the increasing degree of crude oil degradation the bakken shales source of the type ii oils have dgr34s distribution patterns in the reduced sulfur typical of marine sediments the dgr34s values for the type ii oils match most closely the dgr34s value of organic sulfur in the black bituminous shales of the lower bakken

quaternary glaciation of puruogangri the largest modern ice field in tibet abstract the puruogangri the largest modern ice field in the tibetan plateau with an area of over 400 km2 in total is in the inner plateau although it is very difficult to reach the scale of the ice field makes it important to study the quaternary glaciation in this inland area to determine whether there was a unified ice sheet in the tibetan plateau during the quaternary field observation showed that five moraine groups termed moraine i v of terminal moraines and lateral moraines are present located from the snouts of modern glaciers to the piedmont based on geomorphic locations stratigraphic correlation relative weathering reworked degrees by wind action and the esr ages of the sands covering the gobi with erratics as well as through comparison with the quaternary glaciations with numerical ages in western chinese mountains these moraine groups represent the modern moraine the little ice age neoglacial the late stage of the last glaciation and the early stage of the last glaciation respectively the granite boulders of moraine v are scattered for 6 km from the mountain front on an extensive peneplain this suggests that the ancient glaciers in the west slope of the ice field advanced to the piedmont during the late pleistocene but did not integrate with the ice in the mountains nearby to form a unified ice sheet

novel families of tetra and hexacyclic aromatic hopanoids predominant in carbonate rocks and crude oils two novel families of monoaromatic geomarkers related to hopanoids have been separated and characterized in sediments and crude oils the benzohopanes c32 c35 1 and the ring d aromatized 8 14 secohopanoids c27 c35 4 and 5 both series are particularly abundant in many carbonate samples where they amount to approximately 100 p p m per component in some crude oils but can also be detected in other environments the benzohopanes have been separated as pure compounds by high performance liquid chromatography and identified by x ray diffraction the structure of the 8 14 secohopanoids mostly relies on spectroscopic data nmr and ms and comparison with synthetic analogs both families must be formed in the subsurface from bacterial c35 hopanoid precursors but the benzohopanes seem to occur at an earlier stage of sedimentation the two series appear in varying distributions in the different samples and may therefore be potentially useful as geochemical correlation parameters

subglacial comminution in till evidence from microfabric studies and grain size distributions quartz feldspar and chlorite the principal minerals in a basal till from the halasi river catchment in the altay mountains northwestern china are present in approximately equal concentrations in the coarse fraction of the till 1 0 0 125 mm quartz concentrations are significantly higher than those of the other two minerals in the 0 125 0 016 mm size range feldspar and chlorite concentrations are higher than those of quartz in the finest fraction quartz has a strong preferred mode at 0 063 0 032 mm feldspar and chlorite have two weak modes in the silt size range one between 0 063 and 0 032 mm and the other between 0 016 and 0 004 mm thin sections of oriented impregnated samples were used to study crushing and abrasion over 2700 daughter particles were identified as products of comminution of 925 parent grains quartz and feldspar are most likely to be broken into two particles of roughly equal size as are fine chlorite grains however owing to their weakness and cleavage larger grains of chlorite tend to be split into more than two daughter particles sizes of the daughter grains were measured and sizes of the original parent grains were estimated mean parent grain sizes for quartz feldspar and chlorite are 0 129 0 078 and 0 059 mm respectively whereas mean daughter grain sizes are 0 068 0 041 and 0 024 mm respectively the greater percentage reduction in the size of chlorite reflects its tendency to break into more than two daughter particles most grains tend to be crushed only a few large particles seem to have suffered from abrasion

petroleum potential of the middle member bakken formation williston basin abstract the bakken formation is a widespread clastic unit between the mississippian madison group and the upper devonian big valley torquay or three forks formations the formation typically consists of three members a lower and upper organic rich shale and a middle calcareous sandstone and siltstone the three members of the bakken formation exhibit an onlapping relationship and converge and thin toward the margins or marginal shelf areas of the williston basin in manitoba the lower member is absent except for waskada field several correlative lithofacies have been recognized in the middle member the lowermost unit of the middle member is a regressive deposit the upper portions of the middle member show transgressive and regressive cycles and intertidal deposits interfinger with their distal equivalents conventional bakken production is restricted to areas where it is a thermally mature source rock the greater part of bakken production in recent years has been taken from the shale of the upper and lower members although there are outlying fields which produce from a sandstone within the middle member this suggests that there has been a migration of bakken oil from the central portion of the basin the sandstone unit may provide a conduit for migration

esr dating of fault gouge the effect of grain size abstract esr signals of quartz grains in fault gouge have been partially or completely reset by movements on the fault which allows the dating of the last fault movement in order to better understand the zeroing process we have studied the variation in esr signal ad and age in various grain sizes since it can be expected that larger grains will be less affected by stress than smaller grains we propose that a plateau of constant lower age for the smallest grains indicates total resetting this is confirmed in gouge from a fault in california only such samples should be used for dating

bakken madison petroleum systems in the canadian williston basin part 3 geochemical evidence for significant bakken derived oils in madison group reservoirs there have been two different definitions of the upper devonian mississippian bakken madison petroleum systems in the canadian williston basin early studies proposed the bakken shales as the source for oils in both the bakken formation and madison group reservoirs more recent studies suggested two separate sources for these oils thus the bakken oils were interpreted to be derived from the bakken formation shales and the madison group oils from a carbonate source within the madison group the present study utilized quantitative results of molecular markers across gasoline range light hydrocarbons saturated and aromatic hydrocarbon fractions in 122 oil samples to re evaluate the oil oil and oil source relationships the steroid and hopanoid parameters collected in this study have confirmed the diagnostic features for end member bakken and lodgepole sources whereas a range of other molecular markers revealed compositional continuums occurring between the two oil families the recognition of more extensive mixing of bakken derived oils in madison group reservoirs along a sw ne trending fault fracture zone in southeastern saskatchewan indicates focused migration pathways for bakken oils and thus upward resource potentials the results also suggest caution with the use of conventional biomarker data in oil oil and oil source correlation when the different sources concerned contain biomarkers in drastically different concentrations

tracing the source of ancient reworked organic matter delivered to the north atlantic ocean during heinrich events a major effort of the geochemical and paleoclimate community has been to identify the specific sources of the ice rafted debris ird in heinrich layers hls although the general consensus is that the majority of the ird originated from the hudson area of northern canada the specific sources are not well constrained here we compare the diagnostic organic geochemical signature of hls to that of a number of paleozoic outcrops across the former margin of the laurentide ice sheet we show that the biomarker signature of upper ordovician strata from southampton and baffin island is compatible with that found in hls in the labrador sea and north atlantic while the biomarker signature of other paleozoic formations from the former margin of the laurentide ice sheet is not in addition to the biomarker signature key inorganic characteristics 18o end and 87sr 86sr ratios of these formations from southampton and baffin island are consistent with those reported from hls the location of these formations in and around the hudson strait is compatible with palaeo ice flow regimes through the hudson strait allowing for easy entrainment and rapid transport to the ocean based on these results we propose that these specific upper ordovician formations form a main source of ird in hls and hence infer an active role of the hudson strait paleo ice flow in these events