calculation of petroleum masses generated and expelled from source rocks abstract an algebraic scheme for calculating the masses of petroleum formed in mature source rocks has been constructed the scheme exploits routine geochemical measurements and a basic understanding of the behaviour of sedimentary organic matter at elevated temperatures under both laboratory and subsurface conditions application of these techniques to data from a wide range of source rock types has led to the following general conclusions 1 1 major oil and gas generation from kerogen occurs between 120 and 150 c in the subsurface gas generation continues to temperatures 160 c 2 2 oil prone source rocks with average initial potential 5 kgt 1 of rock and average organic carbon contents 1 5 expel 60 90 of the total oil generated 3 3 oil expulsion from leaner source rocks is less efficient most of the oil generated remains in the source rock it is subsequently converted to lighter components at higher temperatures and expelled in the vapour state 4 4 the major loss of organic carbon from rich oil prone source rocks during generation and expulsion means that the petroleum potential and organic carbon content of mature source rocks are much less than their initial immature values hence the algebraic scheme must be used to calculate the initial values before expelled petroleum masses can be determined

geochemical and petrographic characterization of humic coals considered as possible oil source rocks abstract recently several groups of authors have argued that coals should be considered as possible source rocks for oil as well as being source rocks for gas the present study was undertaken with the objective of evaluating the various methods of characterization of maturation levels and oil potentials of coals from within the oil window it was found that the degree of maturation of a coal could not be specified exactly no matter what parameter describing coal rank was used this lack of precision obviously makes it difficult to compare coals especially from the point of view of their petroleum potential which varies during the course of coalification furthermore quantitative evalution of the oil potential of coals is difficult particularly the present day petrographic concept of exinite does not seem very well adapted to this quantitative evaluation differences in oil potential might in fact be better explained by the relative proportions of the various vitrinite macerals which are present rather than by the proportion of exinite in the coal

quantifying gravel overlap and dislodgement forces on natural river bars implications for particle entrainment equations for predicting particle entrainment typically assume that clast weight is the only factor resisting motion in the force balance on individual grains in this work increases in the force required to dislodge surface particles due to overlapping by surrounding clasts is quantified field data were collected at two subaerially exposed bars along the colorado river in central texas usa with median gravel diameters d50 of 37 and 64 mm clast size shape weight the force required for vertical removal and the fraction of clast area covered by surrounding grains were measured small hooks were glued to individual clasts without disrupting their positions and quasi static peak forces required to vertically dislodge each clast were measured using a force gauge clasts were also colored with dye before being dislodged and image analysis was used to calculate the fraction of clast surface area covered by surrounding grains the effect of overlap on the particle force balance is quantified by defining the excess force ratio as the dislodgement force divided by the weight of the clast excess force ratio varies weakly but systematically with clast size lifting larger clasts can require forces up to two times the clast s weight while smaller clasts can require forces up to seven times their weight the fraction of clast surface area covered by surrounding particles is also weakly correlated with excess force ratio by assuming that critical shear stresses are proportional to the excess force ratio the effect that overlap alone may have on particle entrainment is calculated for a given size class the most mobile grains should have critical shear stresses controlled only by their weight however clast overlap also causes broad distributions of critical stresses for partially exposed surface grains the data quantify the significant fraction of bed area that should be less mobile than grain size alone would predict copyright 2011 john wiley sons ltd

controls of oil family distribution and composition in nonmarine petroleum systems a case study from the turpan hami basin northwestern china controls on oil family distribution in tectonically complicated nonmarine petroliferous basins are commonly difficult to isolate because of the varying ages of potential source rocks the complex assemblage of organic rich sedimentary facies and the geographic variability of burial histories the turpan hami basin of northwestern china is an oil bearing intermontane basin where stratigraphic sedimentologic and geochemical controls are sufficient to address each of these issues independently and to determine how they influence the current distribution and composition of liquid hydrocarbons source rock age is one of three major statistically significant discriminators affecting oil family composition both lower middle lower or middle jurassic and upper permian rocks are important source rocks for the basin a newly developed diterpane biomarker parameter can distinguish permian rocks and their correlative oils from jurassic coals and mudrocks and their derivative oils source facies is a second key control on petroleum occurrence and character a variety of biomarker parameters that reflect source rock depositional conditions are indexed to rock samples from interpreted depositional environments by erecting rock to oil correlation models the biomarker parameters separate oil families into end member groups group 1 oils lower middle jurassic peatland swamp facies high land plant input less reducing conditions group 2 oils lower middle jurassic profundal lacustrine facies high algal input more reducing conditions and group 3 oils upper permian lacustrine facies high algal stratified anoxic conditions burial history exercises a third major control on petroleum distribution source rock maturation modeling can demonstrate that relatively uninterrupted burial in the asymmetrically subsiding northern turpan hami area taibei depression exhausted upper permian sourced rocks by the late cretaceous which led to southward migration of upper permiansourced oils group 3 into triassic reservoirs of southern and southwestern turpan hami tainan and tokesun depressions subsequent to uplift of the central basin thrust that currently partitions taibei from tainan lower middle jurassicsourced oils were expelled in the taibei depression by paleoceneeocene time which locally charged jurassic and cretaceous reservoirs groups 1 and 2 forming turpan hami s largest oil accumulations in the basin

pore types and pore network evolution in upper devonian lower mississippian woodford and mississippian barnett mudstones insights from laboratory thermal maturation and organic petrology abstract pore evolution models from immature organic matter om rich barnett 0 42 r o and woodford 0 49 r o mudstones were compared with models previously developed from low maturity om lean boquillas eagle ford equivalent mudstones to investigate whether 1 different mineralogy siliceous vs calcareous exerts different catalytic and sorption effects and influences om pore origin and evolution and 2 different types of macerals show different om pore evolution history laboratory gold tube pyrolysis scanning electron microscopy sem and thin section petrography organic petrography and geochemical characterization were used to investigate the role of bulk mineralogy maceral type and thermal maturation on om pore evolution results suggest that mineralogy has little impact on om pore development and evolution macerals identified using both sem platy om particulate om organic mineral admixtures tasmanites and organic petrology vitrinite inertinite amorphous organic matter aom bituminite telalginite leiosphaeridia tasmanites do affect the origin and evolution of om pores owing to differences in chemical compositions generation kinetics and activation energy distributions between tasmanites matrix bituminite and other types of macerals leiosphaeridia and tasmanites in woodford mudstone samples exhibit a delay in onset and a shorter period of petroleum generation and pore development compared to the matrix bituminite in the barnett and woodford mudstone samples pre oil solid bitumen was observed to have migrated into initial primary mineral pore networks at the bitumen generation stage in both barnett and woodford samples at higher levels of thermal maturation the volume of primary mineral pores decreases and the pore volume composed of modified mineral pores and om pores becomes greater pore evolution and pore type heterogeneity in these mudstones is a function of the initial mineral pore network types of kerogen and macerals and generation kinetics of individual macerals upon thermal maturation

the petroleum potential of tertiary coals from western indonesia relationship to mire type and sequence stratigraphic setting abstract more than 500 deltaic sediments from 14 basins in western indonesia were subjected to detailed geochemical petrographic and palynological analysis the resultant data represent each of the main peat forming tectonostratigraphic episodes paleogene syn rift transgressive paleogene neogene post rift transgressive and neogene syn tectonic regressive of the indonesian tertiary the coals are hydrogen rich with average hydrogen index hi of 250 300 and atomic h c ratios of 1 0 1 3 where immature paleogene coals from syn rift transgressive systems tracts are more hydrogen rich than neogene coals from syn tectonic regressive systems tracts and upon pyrolysis yield lower gas oil ratios implying they are more oil prone pliocene coals from a strongly regressive sequence in the sumatran fore arc are very hydrogen poor with average hi of 138 indonesian coals display a systematic increase in hi with increasing rank peaking at a tmax of c 430 c suggesting that rock eval pyrolysis underestimates petroleum potential in low rank coals the increase in hi is accompanied by a decrease in s1 toc ratio and the disappearance of suberinite and resinite reflecting the assimilation of these macerals into the coal matrix with increasing diagenesis petrographic analyses reveal a very poor correlation between liptinite content and hi the term detrovitrinite index di is coined to describe the ratio of detrovitrinite total vitrinite a better relationship between hi and di suggests that vitrinite type is a more important control on petroleum potential than liptinite content the coals are classified into four sub types i iv on the basis of their pyrolysis potential and petrographic composition sub types i ii and iii are low ash coals and are likely to have been deposited in raised mires sub type i is hydrogen rich and primarily represents middle to late miocene coals deposited in a regressive megasequence sub type ii coals are hydrogen poor and occur in multiple tectonostratigraphic settings sub type iii consists of very hydrogen poor pliocene coals from the rapidly subsiding west sumatran fore arc sub type iv is hydrogen rich and consists of high ash eocene coals deposited in submerged mires in a transgressive syn rift setting a close relationship between hi and tissue preservation index tpi suggests that the degree of degradation of the peat is an important factor in determining petroleum potential highly degraded peats result in hydrogen rich coals with a higher proportion of vitrinite of detrital or allochthonous origin the degree of degradation is most likely related to the amount of time the peat spends within the zone of influence of the water table and is unlikely to be directly related to tectonostratigraphic setting

simulated petroleum generation studies by hydrous pyrolysis of a tertiary coal from northern cambay basin in india in the northern cambay basin ahmedabad mehsana block abundant coal seams occur at depths of 1000 1700 m the role such coals can play in hydrocarbon hc generation has not been determined hydrocarbon generation from a core sample with a hydrogen index hi 268 mg hc g total organic carbon toc oxygen index oi 19 mg co2 g toc and vitrinite reflectance in oil vro 0 38 has been simulated by hydrous pyrolysis at a temperature of 325 c for 2 10 50 and 100 h it has been observed that generation is in accordance with the model kerogen asphaltenes hydrocarbons the peak oil generation stage is reached at 0 89 vro the peak oil expulsion stage occurs at 0 91 vro although hydrocarbons are generated from 0 75 vro onwards the results indicate that these coals have not contributed towards hydrocarbon reserves of northern cambay basin

coal as a source rock for oil a review the geological debate about whether and to what extent humic coals have sourced oil is likely to continue for some time despite some important advances in our knowledge of the processes involved it is clear that not only liptinites but also perhydrous vitrinites have the potential to generate hydrocarbon liquids in the course of natural coalification some liptinites especially alginite cutinite and suberinite contain a higher proportion of aliphatic moieties in their structure than other liptinites such as sporinite and resinite and are therefore more oil prone it is of potential value to be able to predict the several environments of deposition in which coals with high liptinite contents or containing perhydrous vitrinites may have been formed review of the distribution of oil prone coals in time and space reveals that most are jurassic tertiary with key examples from australia new zealand and indonesia methods based both on experimental simulations and the examination of naturally matured samples have been used to determine the order of generation of hydrocarbons from different macerals results are not entirely consistent among the different approaches and there is much overlap in the ranges of degradation but it seems probable that in the natural environment vitrinites begin to generate early followed by labile liptinites such as suberinite then cutinite sporinite and finally alginite petroleum potential may be determined by experimental simulation of natural coalification or inferred through various micro techniques especially fluorescence and infrared ir spectroscopy or bulk techniques such as elemental analysis and 13c nmr spectroscopy the latter three techniques enable a measure of the polymethylene component of the coal which now appears to be one of the best available approaches for determining petroleum potential no method of experimental simulation of petroleum generation from coals is without criticism and comparative results are highly variable however hydrous pyrolysis confined pyrolysis and forms of open system hydrous pyrolysis approach acceptable simulations whether and to what degree generated liquid hydrocarbons are expelled has long been the central problem in oil from coal studies the structure of vitrinite was believed until recently to contain an interconnected microporous network in which generated oil would be contained until an expulsion threshold was attained recent studies show the pores are not interconnected combined with a dynamic model of pore generation it now seems that expulsion of hydrocarbons is best explained by activated diffusion of molecules to maceral boundaries and ultimately by cleats and fractures to coal seam boundaries the main reason for poor expulsion is the adsorption of oil on the organic macromolecule which may be overcome 1 if coals are thin and interbedded with clastic sediments or 2 if the coals are very hydrogen rich and generate large quantities of oil the existence of oil in vitrinite is attested to by solvent extractions fluorescence properties and by microscopic observations of oil and bitumen experimental simulation of expulsion of oil from coals has only recently been attempted the relative timing of release of generated co2 and ch4 could have considerable importance in promoting the expulsion of liquid hydrocarbons but the mechanism is unclear as it is universally agreed that dispersed organic matter dom in some shales readily generates and expels petroleum it is curious that few consistent geochemical differences have been found between coal macerals and dom in interbedded shales unambiguous evidence of expulsion from coals is limited and in particular only a few commercial oil discoveries can be confidently correlated to coals these include upper cretaceous fruitland formation coals in the usa from which oil is produced new zealand tertiary coals and middle jurassic coals from the danish north sea it is likely that coals have at least contributed to significant oil discoveries in the gippsland basin australia in the turpan basin china and in the kutei and ardjuna basins in indonesia but this remains unproven early reports that early jurassic coals in mid norway were a major source of the reservoired oils have been shown to be inaccurate none of the proposed rules of thumb for generation or expulsion of petroleum from coals seem particularly robust decisions on whether a particular coal is likely to have been an active source for oil should consider all available geological and geochemical information the assumptions made in computational models should be well understood as it is likely with new understandings of processes involved that some of these assumptions will be difficult to sustain

main oil generating macerals for coal derived oil a case study from the jurassic coal bearing turpan basin nw china abstract this paper examines the geochemical characteristics of pyrolysates from macerals such as the alginite sporinite cutinite collotelinite and collodetrinite isolated from jurassic coals and investigates their relative contributions to oil potential in respect to the jurassic coal measures in the turpan and other basins of northwest china the alginite pyrolysate has the lightest carbon isotopic composition followed by the sporinite and cutinite while the collotelinite and collodetrinite pyrolysates show comparatively heavy carbon isotopic compositions pyrolysates from the alginite sporinite and cutinite demonstrate much lower pr ph ratios than those from the collotelinite and collodetrinite regarding the distributions of regular biomarkers such as steranes and hopanes the alginite pyrolysate is comparatively rich in c 27 steranes followed by pyrolysates from the sporinite and cutinite whereas pyrolysates from the collotelinite and collodetrinite contain little or undetectable c 27 steranes furthermore the pyrolysates from different kinds of macerals have remarkably different gammacerane concentrations the gammacerane concentrations in pyrolysates from the alginite and cutinite are higher than that from the sporinite though these macerals were separated from the same coal whereas the collotelinite and collodetrinite pyrolysates have almost no gammacerane the experimental results suggest that liptinite content in one given coal e g alginite sporinite and cutinite controls the biomarker distributions in the coal derived oils mass balance calculations of carbon isotopic compositions from the maceral pyrolysates show that the carbon isotopic composition of liquid hydrocarbons generated by organic matter in mudstone is very similar to that of most of the oils in the jurassic coal bearing basins of northwest china while liquids from coal are much heavier than that of the oils this indicates that the mudstone is likely to be the major source rocks of the oils and coals likely to be the subordinate source rocks mass balance calculation based on the maceral contents and hydrocarbon generative potential suggests that liptinites in mudstone in the jurassic coal measures of the turpan basin generate about 70 of oils while the vitrinites produce about 30 of the oils therefore the hydrogen rich liptinites alginite sporinite and cutinite are the main oil generating macerals while vitrinites collotelinite and collodetrinite are secondary oil generating macerals in the jurassic coal bearing turpan basin and other jurassic basins of northwest china

source rock evaluation by pyrolysis gas chromatography a pyrolysis gas chromatography system has been developed for the rapid evaluation of potential source rocks for the determination of organic richness and maturation this system uses the pyrolysis methods previously described however the determination of hydrocarbon production type and the identification of contamination by migrated hydrocarbons or drilling additives are accomplished by gas chromatographic gc analysis of the thermal extracts and pyrolysis products of rock samples or isolated kerogens the production type is recognized either qualitatively by gc fingerprint traces or quantitatively by hydrocarbon composition c1 to c6 c6 to c11 c11 from the kerogen peak ii pyrolysate oil prone erogens are recognized by gc traces with a full spectrum of c1 to c28 hydrocarbons or by high concentrations of c11 compounds in contrast gas prone kerogens are characterized by the predominance of light hydrocarbons from c1 to c4 and higher contributions of aromatic compounds mixed type production is intermediate in character between the two contaminants are identified from the gc analysis of the thermally extractable material in peak i possible mineral organic matter reactions during sample heating make interpreting data from whole rock samples more difficult

petrographical and geochemical characterization of sub bituminous coals from mines in the cesar rancheria basin colombia abstract tertiary coals from the la jagua and calenturitas coal mines in the cesar sub basin colombia were investigated for the first time using organic petrological and organic geochemical methods to assess the thermal maturity and palaeoenvironmental conditions during peat accumulation thirteen seams were sampled from the los cuervos formation at two mines evaluation based on organic petrological analyses and rock eval pyrolysis reveals that the coals are thermally immature and of sub bituminous b to sub bituminous a rank with a predominance of type iii mixed with type ii kerogen 22s 22s 22r homohopane ts ts tm mpi mpr and 1 mp 9 mp ratios are very low this low thermal maturity corresponds to high volatile matter contents petrographically the la jagua and calenturitas coals are dominated by vitrinite with low to high amounts of inertinite and low to moderate amounts of liptinite the detailed petrographic data indicate a predominantly herbaceous plant input and oxidative conditions during deposition mostly with strong tissue destruction further conclusions are deduced from petrographic ratios such as tissue preservation gelification groundwaterac and vegetation indices ash and sulfur contents iso and n alkane distribution and 17 h homohopane ratio in summary the data support a formation in tropical ombrogenic rather wet peats with high bacterial activity

depositional palaeoenvironment and economic potential of khadsaliya lignite deposits saurashtra basin western india based on petrographic palynofacies and geochemical characteristics abstract the lignite and associated shale of the khadsaliya clays formation eocene of saurashtra basin india have been studied organic petrographic palynofacies and organic geochemical analyses have been carried out to deduce the depositional palaeoenvironment including the assessment of the hydrocarbon potential of this sequence petrographically the lignites constitute huminite macerals in dominance av 60 the organic facies as derived from maceral composition and biomarker data suggests that the peat biomass was formed from woody forest vegetation consists of angiosperms and pteridophytes microbial activity was also prominent over the peat biomass the peat biomass was deposited in tropical subtropical humid climatic conditions under deltaic control and brackish water influence further there are signatures of intermittent floods in the mire and is evident from the shift from mesotrophic to rheotrophic conditions the organic matter has been categorized into two palynofacies and is derived from degraded terrestrial biomass the extrapolation of tyson s app diagram and pr n c17 vs ph n c18 plot suggest that deposition took place in dysoxic to sub oxic conditions the huminite reflectance values 0 30 0 38 av 0 34 rr suggest that lignites are less mature and have reached up to lignitic stage low rank b of coalification the geochemical proximate ultimate analyses reveal that the lignites are characterized by high moisture content av 18 and relatively low ash yield av 27 the volatile matter yields and carbon contents are moderately high whereas fixed carbon sulphur and oxygen contents are average and hydrogen and nitrogen contents are relatively low rock eval pyrolysis data indicate that the hydrogen index values of the samples vary between 23 and 477 mg hc g toc av 188 mg hc g toc the tmax values of the lignites range between 377 and 433 c av 418 c along with the presence of hopanes suggesting the immature nature of the deposits hi vs tmax s2 vs toc hi vs oi and h c vs o c plots of the studied samples indicate that the organic matters are a mix of type ii iii kerogens the types of kerogen along with high toc contents av 33 wt indicate the ability of lignite bearing sequence of khadsaliya to generate mix of oil gaseous hydrocarbons upon maturation

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

marine influence helps preserve the oil potential of coaly source rocks eocene mangahewa formation taranaki basin new zealand abstract many cretaceous cenozoic coaly source rocks in australasian and southeast asian basins were deposited in coastal plain environments yet the effect of early diagenetic marine influence on their oil potential is not well understood an integrated organic geochemical and petrographic study of humic coals from the eocene mangahewa formation taranaki basin new zealand was undertaken with coals predominantly from raised mire petrofacies with subordinate proportions from planar mires the total s content of 0 63 4 4 dry ash free indicated very slight to strong degrees of marine influence other than minor addition of inferred mangrove derived suberinite and associated liptodetrinite the degree of marine influence had no obvious effect on maceral or plant tissue abundance however hydrogen index hi values were up to ca 150 109 mg hc g toc higher and total c 6 oil potential up to ca 140 43 mg g toc higher among the more strongly marine influenced coals correlation of organic s with solvent extract parameters pristane phytane c 27 c 29 diasteranes steranes c 29 steranes hopanes c 35 c 35 c 34 homohopanes and oleanane index suggested that inundation of brackish water into the early diagenetic peat forming environment enhanced the bio resistance of higher plant and other lipids through sulfurization thereby helping to preserve more of the inherent h content and total oil potential of the original peat biomass conversely marine influence had only a minor effect on the capacity of mangahewa coals to generate paraffinic oil total n c 6 and non volatile n c 15 paraffinic oil potentials were instead controlled primarily by the abundance of leaf derived cutinite and associated liptodetrinite this in turn was dependent on the type of peat mire facies with planar mire facies having better potential for preservation of leaf litter than raised mire facies because of their generally higher groundwater level marine influence is nonetheless beneficial for paraffinic oil charge from coaly source rock sequences in that the associated higher his enhance the efficiency and quantum of paraffinic oil expulsion through increased saturation of the coal pore system

geochemical characteristics of carboniferous coaly source rocks and natural gases in the southeastern junggar basin nw china implications for new hydrocarbon explorations abstract the upper carboniferous coaly source rocks are verified to be developed in the southeastern junggar basin which is lithologically composed of carbonaceous mudstones and mudstones according to the geochemical total organic carbon rock eval and biomarker fingerprints and organic petrology analyses the carboniferous source rocks are primarily gas prone characterized by kerogen type iii and were deposited in an oxidized sub oxidized brackish environment significantly contributed by terrigenous higher plants carbonaceous mudstones are generally more oil prone in comparison with the mudstones the measured vitrinite reflectance t max and sterane isomers indicate that the source rocks are at immature early gas generation stage and have not entered the peak gas generation stage natural gases are coal type gases derived from the carboniferous source rock the maturities of them are highly inconsistent with those of source rock samples based on 2 d basin modeling natural gases were generated from the highly mature coaly source rocks in the fukang depression and migrated upward to the uplift via the p c regional inconformity

the petroleum potential of some tertiary lignites from northern greece as determined using pyrolysis and organic petrological techniques abstract oil condensate and gas have recently been discovered in the thermaikos gulf area of northern greece the source of these hydrocarbons is not known although there is a possibility that more mature equivalents of certain tertiary brown coals and lignites may be responsible a contribution from tertiary terrestrial organic matter to the epanomi oil is supported by its biomarker distributions especially the predominance of triterpenoid compounds other than hopanes in the m z 191 mass fragmentogram in this study the hydrocarbon potential of a suite of greek tertiary lignites is first examined using rock eval analysis three samples are then further investigated using organic petrography and gas chromatography gc and gas chromatography mass spectrometry gc ms of the extracted hydrocarbon fractions as well as by hydrous pyrolysis an intermontane lignite 6og 5 contains fluorescing huminite together with resinite on extraction this resinite is found to be of predominantly diterpenoid origin rock eval and hydrous pyrolysis support previous proposals that diterpenoid resinite needs a lower activation energy to generate hydrocarbons than most other types of organic matter a sample of a lignite deposited in a deltaic environment mm 3 contains a more diverse collection of liptinite macerals with resinite again predominating the resinite appears to be mostly of triterpenoid and sesterterpenoid origin the best hydrocarbon potential is shown by a sample deposited in a lagoonal environment kas 3 little discrete resinite is observed in this sample but it does contain abundant fluorescing huminite although it has a low s 1 s 1 s 2 ratio it gives a high yield on solvent extraction during which a significant fraction of the s2 is removed the fluorescence of the huminite after extraction is greatly reduced the hydrocarbons of the extract are believed to be predominantly derived from triterpenoid resinite unlike the pyrolysates of the other two lignites but in common with the epanomi oil the triterpenoids in the kas 3 pyrolysate are dominated by resin derived compounds rather than hopanes this and other similarities between the composition of the pyrolysates of kas 3 and the oil support the possibility that a more mature equivalent of this lignite could be the source of the epanomi oil

hydrocarbon generation from deltaic and intermontane fluviodeltaic coal and coaly shale from the tertiary of texas and carboniferous of nova scotia abstract selected samples of coal and coaly shale from southeastern texas depositional environment deltaic age paleocene eocene ro 0 25 0 75 and nova scotia depositional environment intermontane swamp delta and lacustrine age carboniferous westphalian a d ro 0 67 0 70 were analyzed by fluorescence microscopy rock eval pyrolysis nmr anhydrous pyrolysis temperature programed and flash and hydrous pyrolysis to evaluate the hydrocarbon potential and hydrocarbon types based on maceral assemblages palynofacies and hydrocarbon potential these coal and coaly shale samples are classified as humic mixinitic mixed and sapropelic compared to humic and sapropelic as defined by stach et al coal petrology gebruder borntraeger berlin 1982 mixinitic or mixed coal and coaly shale containing mainly humodetrinite and lipodetrinite generated more than 10 pyrolysate expelled oil oil in wash fraction remaining coal extract and show a bimodal n alkane distribution derived from cutinite suberinite and alginite pyrolysis of humotelinite humocollinite rich and liptinite poor humic coals generated low amounts

geochemical characteristics of tertiary coal bearing source rocks in xihu depression east china sea basin abstract this study aims at investigating hydrocarbon generation potential and biological organic source for the tertiary coal bearing source rocks of pinghu formation middle upper eocene in xihu depression east china sea shelf basin another goal is to differentiate coal and mudstone with respect to their geochemical properties the coal bearing sequence has a variable organofacies and is mainly gas prone the coals and carbonaceous mudstones in comparison with mudstones have a higher liquid hydrocarbon generation potential as reflected by evidently higher hi values averaging 286 mg hc g c and h c atomic ratios round 0 9 the molecular composition in the coal bearing sequence is commonly characterized by unusually abundant diterpenoid alkanes dominant c29 sterane over c27 and c28 homologues and high amount of terrigenous related aromatic biomarkers such as retene cadalene and 1 7 dimethylphenanthrene indicating a predominantly terrigenous organic source the source rocks show high pr ph ratios ranging mostly from 3 5 to 8 5 and low mdbts mdbfs ratios

characterization of mangrol lignite gujarat india petrography palynology and palynofacies a multidisciplinary approach petrographical palynological and palynofacies has been adopted to characterize and assess the depositional conditions of eocene mangrol lignite deposit from western india the petrographic study reveals that the lignite is composed predominantly of huminite macerals produced from a woody forest the reflectance values range from 0 27 to 0 32 indicating a lignite rank the variable values of tissue preservation index tpi and gelification index gi as well as the maceral composition indicate fluctuating ground water conditions and difference in the type of vegetation during peat accumulation the palynofloral spectrum suggests the presence of angiosperms including mangrove and pteridophytes belonging to families of bombacaceae annonaceae alangiaceae ctenolophonaceae liliaceae osmundaceae schizaeaceae matoniaceae cyatheaceae among others as the peat biomass source materials for the origin of these lignites the palynomorphs indicate that a tropical to sub tropical climatic condition was present during deposition of the peat biomass and that the original mire likely occurred in a coastal setting this interpretation is strongly supported by palynomorphs with affinity to brackish water taxa palynofacies studies suggest peat deposition under dysoxic conditions in a marginal marine setting high amount of amorphous matter kerogen type i in the shale bed above the lignite and very high content of liptinite in lignite mainly comprised of resinite and liptodetrinite suggest the potential of both shale and lignite for the generation of hydrocarbon

influence of in situ bitumen on the generation of gas and oil in new zealand coals new zealand coals of peat to high volatile bituminous rank have been studied in order to assess the effect of in situ bitumen soluble in a methanol acetone chloroform azeotrope on petroleum potential during progressive maturation both non extracted and extracted coals as well as the extracted bitumen itself were analyzed using rock eval and pyrolysis gas chromatography the difference in yields between non extracted and extracted coals attributable to the influence of bitumen were compared with direct measurements made on the bitumen itself major compositional changes in pyrolysis products were seen when the bitumen was finely dispersed throughout the kerogen matrix notably second order reactions between kerogen and bitumen during pyrolysis reduce primary gas yield and enhance both oil yield and potential secondary gas yield the stabilization of free radicals and prevention of recombination repolymerization processes have been attributed to the presence of the dispersed in situ bitumen these results demonstrate that petroleum formation in coals likely proceeds via intermolecular interactions and not simply first order cracking the common procedure of employing solvent extraction prior to pyrolysis is clearly not appropriate when assessing the petroleum potential of coal

petroleum generation and migration in coal seams of the carboniferous ruhr basin northwest germany a series of 64 coal and clastic rock samples of westphalian age was taken from five narrow 3 m depth intervals between 1200 and 1530 m depth and studied by geochemical and petrological methods maturity increases regularly with increasing depth as indicated by several maturity parameters the influence of organic facies is evident in the uppermost coal seam 0 70 rr where a hand picked vitrinite contains less total extract and less saturated long chain hydrocarbons than a directly adjacent sporinite rich coal extracts from deeper and more mature coals are less affected by facies changes probably due to enhanced petroleum redistribution in the seams total yield and gross composition of extracts in the deepest seam 0 92 rr which is directly overlain by sandstone seem to be influenced by the preferential expulsion of saturated hydrocarbons

from mangroves to petroleum precursors an example from tropical northeast australia missionary bay north queensland is an example of a tropical modern depositional environment dominated by mangrove swamps several major sedimentary facies are represented coastal sands brackish water peats intertidal organic muds on which the mangroves are developed low tide muds channel deposits inshore muds sandy bay bottom muds inshore sands inshore carbonate sands and deltaic sands large amounts of mangrove litter are carried in nearly anoxic creeks to the bay bay bottom sediments have only a shallow upper oxidized layer and are strongly reducing at depth organic carbon values for most of the inshore sediments range from 1 to 2 total lipid content of the bay bottom sediments is very high sediments average 0 15 by weight total lipids or about 6 of the total organic carbon these high values are attributed to the lipid rich mangrove litter sedimentation rates for the bay bottom sediments are high about 1 cm year progradation rates are also high about 1 m year including offshore fringing reefs and inshore sands the total area of the system is several hundred square kilometers anoxic conditions of transport and deposition plus the high sedimentation rates suggest that the low tide muds and bay bottom muds are excellent source rock analogs progradation and accumulation could result in a section about 50 m thick with lipid rich sediments interfingering with barrier sands fringing reefs channel sands and deltaic sands the section will be capped and sealed by brackish water peats with a mud matrix this system is of potential value as a conceptual model for hydrocarbon accumulations on ancient tropical coastline

investigation on the lignite deposits of surkha mine saurashtra basin gujarat western india their depositional history and hydrocarbon generation potential abstract an integrated approach is adopted to study the lignite deposits of surkha mine associated with the khadsaliya clays formation eocene of saurashtra basin western india the compilation of detailed investigation includes organic petrographical palynofacies and geochemical analyses the type and amount of organic matter and its relation to palaeoenvironmental conditions have been determined and discussed along with its significance as hydrocarbon source the macerals of huminite group show dominance av 61 over the liptinite and inertinite groups the petrographical indices gi tpi gwi vi indicate wood dominated precursors of peat were deposited in limno telmatic to telmatic regime under mesotrophic hydrological conditions in palynofacies analysis it is observed that the particulate organic matter is dominated by the phytoclasts group av 69 followed by the amorphous organic matter aom and palynomorphs the biomarker signatures show angiosperm and gymnosperm source vegetation the presence of sesquiterpenoids indicate the occurrence of dipterocarpaceae flora suggesting the existence of rain forest vegetation in the vicinity of depositional site the kaurane type of diterpenoids suggest the presence of conifers among the source flora the extrapolation of organic matter data on tyson s app diagram along with the pr n c 17 vs ph n c 18 plot indicate that the deposition took place in dysoxic suboxic conditions with intermittent shifting of the environment in proximal settings the huminite reflectance values av 0 31 r r show a good correlation with gross calorific values av 3917 cal g and average t max value 416 c of the lignites furthermore the abundance of thermally unstable hop 17 21 ene and hopane indicate immature stage of lignites these lignites contain high toc av 35 wt and low ash yields the volatile matter carbon and oxygen contents are relatively high whereas sulphur content is moderate and hydrogen and nitrogen contents are comparatively low in all the lignite samples the hydrogen index values vary between 53 and 538 mg hc g toc the atomic values of h c range from 0 47 to 1 04 and of o c from 0 20 to 0 29 overall the lignite bearing sequence is characterized by type ii iii admixed kerogens organic matters and has potential to generate hydrocarbons upon maturation

reaction kinetics of gas generation in selected source rocks of the west siberian basin implications for the mass balance of early thermogenic methane abstract about one third of the actual global recoverable natural gas reserves is accumulated in the west siberian basin in several super giant and mega giant as well as numerous smaller gas fields the elucidation of the nature of this gas its mechanisms of formation and accumulation are still a matter of discussion for instance it is still not yet clear whether the enormous dry gas accumulations in cenomanian reservoirs are of microbial early thermogenic or catagenetic metagenetic origin or if they represent a mixture of these possible formation mechanisms the present contribution provides new results on the thermal gas generation properties of selected source rocks of the cretaceous pokur formation in the west siberian basin eight selected source rock core samples of the pokur formation and a recent peat sample of the same area were submitted to open system programmed temperature pyrolysis in order to quantify the formation of individual gas compounds i e methane as well as c2 and c3 hydrocarbons the rock samples were selected according to geological age and maturity i e from the aptian albian and cenomanian with the most immature samples from the latter organic carbon contents comprise the whole range from 3 to more than 60 the elevated values representing typical lignites a reaction kinetic model system was applied to the generation curves of the gases resulting in activation energy distributions and the corresponding pre exponential arrhenius factors the kinetic data were combined with the temperature history of two selected wells of the urengoy area obtained from basin modelling in order to calculate the gas generation on the geological time scale it was found that even for the low temperatures occurring in the pokur formation early gas generation could have taken place to a certain yet small degree under the assumption of a respective catchment area and the accumulation of this gas in the reservoirs however methane quantities are in the order of magnitude of the urengoy gas accumulation thus early thermogenic methane could at least partially contribute to the gas accumulated in the reservoirs

evaluation of petroleum generation from resinites by hydrous pyrolysis hydrous pyrolysis experiments are useful in evaluating the composition yield and kinetics of liquid hydrocarbons generated from potential source rocks using this technique on a representative set of resinites revealed that fossil resin does not generate a light naphthenic crude oil gas chromatograms of liquid hydrocarbons generated by resinites are dominated by aromatic peaks and show no resemblance to commercially produced crude oils resinites may make minor contributions to conventionally sourced crude oils but their limited occurrence inhibits their potential as a prolific source of petroleum on a basinal scale data from the natural system and pyrolysis experiments also indicate that resinites do not generate liquid hydrocarbons at abnormally low levels of therm l maturity

the stable isotope geochemistry of australian coals abstract d h 13 c 12 c 18 o 16 o and 34 s 32 s ratios in the organic matrix and organic solvent extracts of australian coals and in the fluids and minerals associated with these coals are reported and reviewed against similar isotopic data for coals from other regions where coals are immature original isotopic differences between macrolithotypes and between solvent extracts lipid concentrates and insoluble residues are largely preserved however with increasing maturity these characteristic differences particularly those between macrolithotypes are rapidly erased conversely where as indicated by low total sulfur contents coals of cretaceous to permian age were deposited under essentially freshwater conditions 34 s values for the organically bound sulfur remain remarkably constant at 4 3 relative to meteoritic sulfur in similar younger tertiary coals the organic sulfur is markedly enriched in 34 s five distinctive isotopic patterns which may be interpreted in terms of the environment of sulfate reduction can be recognized from 34 s 32 s ratio measurements on the various forms of sulfur in australian coals isotopic studies of seam gas hydrocarbons collected in situ show these to be unexpectedly strongly depleted in the heavier isotopes of hydrogen and carbon relative to natural gases from proposed humic sources furthermore no pronounced increase in the 13 c content in methane with increase in rank of the parent coal was observed in addition several sources of associated carbon dioxide have been delineated including normal maturation processes invasion of the seams by magnetic carbon dioxide and interaction of the coal with intrusive magma isotopic exchange between free seam gases is not accepted as an explanation for some unusual isotopic fractionations seen rather the data suggest that these gases may be formed in a state approaching isotopic equilibrium this argument also satisfactorily explains the isotopic compositions of primary siderite and secondary calcite associated with bituminous coal seams however where seams are invaded and permeated with externally derived carbon dioxide usually of magnetic origin carbonates are frequently absent presumably as a result of the action of carbonic acid

simple kinetic models of petroleum formation part iii modelling an open system abstract the movement of petroleum from organic rich source beds to potential carrier beds is the net result of two processes expulsion the release of generated petroleum from kerogen within the source bed and primary migration flow of a petroleum phase through the inorganic void networks of the source bed and all other intervening fine grained rocks expulsion is by far the more important process within the source bed orgas a simple zero dimensional model of the source rock as an open system explicitly models expulsion concurrent with oil and gas generation and oi lgas cracking as a storage threshold problem oil and gas are retained adsorbed absorbed within kerogen until their concentrations exceed the respective sorptive capacity of the residual organic carbon 0 1 and 0 02 g g ck 1 the initial hydrogen index hl 0 controls the important balance between potential sorbate petroleum and sorbant residual carbon using simple geochemical measurements the initial organic carbon is divided into initial oil inert kerogen and oil and gas generative reactive kerogen components reactive kerogens are assigned to one of five global kinetic organofacies with pre determined kinetic parameter sets governing separately rates of oil and gas generation kinetic parameters governing the rates of oil cracking within the source rock are predicted from hl 0 the two most important determinants of source rock behaviour are organofacies and hl 0 at a reference constant heating rate of 2 c ma 1 the projected oil expulsion threshold for typical organofacies members increases in the order a de 100 110 120 135 c f typically expels no oil an order of magnitude increase decrease in heating rate increases decreases these thresholds by ca 15 c typical cumulative gas mass fractions in their ultimate expulsion products are a f 0 25 0 3 0 25 0 65 and 1 0 g g 1 a value of 200 mg hc g c 1 is an approximate minimum hl 0 prerequisite for oil expulsion irrespective of absolute petroleum potential p 0 as a family coals vary dramatically in their expulsion behaviour as their hl 0 ranges both above and velow this value primary migration is efficient for expulsive source rocks movement within the source bed is limited only at low p 0 a source rocks total genetic potential p 0 thickness becomes important during migration outside the source bed it potentially restricts the primary migration distance and the excess of petroleum available for secondary migration and entrapment we evaluate primary migration approximately using a small migration loss factor no more than about 10 saturation of porosity or 1 mg g 1 coupled with an understanding of fluid potential gradients which determine migration direction within the stratigraphic architecture ultimately kerogen degradation and oil to gas cracking in the source rock are the rate limiting processes in petroleum accumulation

geochemistry of oil seeps and rock samples of the early tertiary section from the northandean flank of the venezuelan andes abstract an organic geochemical study of oil seeps and early to middle tertiary source rocks of the northandean flank naf of the venezuelan andes range was performed to establish the possible contribution of terrestrial source rocks to the oil accumulations in the unexplored southern part of the maracaibo basin source rocks were identified within the paleocene barco and los cuervos formations and the late eocene oligocene carbonera formation biomarker distributions indicate a terrigenous organic source for these units geochemical modeling performed by parnaud et al 1995 indicated plio pleistocene oil generation for the orocue group and middle miocene to plio pleistocene oil generation for the carbonera formation geochemical modeling also indicates that the quantity of crude oil expelled by the carbonera formation is four times that expelled by the orocue group barco and los cuervos formations a northeast to southwest variation from marine to terrestrial oil seeps was identified based on sterane and terpane distributions the marine oil seeps appear to be derived from the la luna source rocks the characteristics of the mixed oils suggest contributions from different sources la luna and a terrestrial source rock most likely the orocue group or carbonera formation coals source facies similar to those in the los cuervos and carbonera formations coals are most likely the main source rocks of terrestrial oil seeps in the naf

oleanane parameter verification by quantitative study of the biomarker occurrence in sediments of the niger delta abstract the variation of the absolute concentration of oleananes in three selevted sedimentary columns of the tertiary niger delta is paralleled by the corresponding oleanane parameter op profile thereby confirming that the latter can be utilized for estimating the relative contribution of terrigenous organic matter it is shown that op features a dynamic range especially at the oil generative window ogw and can precisely delimit the top of the ogw which for the niger delta is shown to coincide approximately with the 80 c isotherm and ro 0 55 this study provides the first direct evidence of the inadequacy of vitrinite reflectance as a maturity parameter for type iii kerogen furthermore based on the new findings an alternative model for oleanene oleanane interconversions in the geosphere is proposed

determining the petroleum generating potential of coal using organic geochemistry and organic petrology abstract the ardjuna basin of northwest java is typical of many tertiary basins in that it contains high wax crude oil pyrolysis gas chromatography revealed that potential precursors of long chain waxy paraffins are present in coals of the talang akar formation and are most abundant in those that are rich in matrix liptinite conversely it was not possible to estimate waxy oil generating potential using rock eval because pyrolysates from talang akar coal are mainly comprised of naphthenic and aromatic compounds these being derived from resinite and fluorescing vitrinite because of a controlling influence by the abundance of these macerals changes in hydrogen index could not be used to assess maturity resinite and related macerals might play an especially important role in petroleum expulsion as evidenced by their high genetic potential and hence inherent capability of saturating the source rock pore system it is speculated that their maturation products while not constituting typical crude oil might pervade the coal fabric deactivate adsorptive sites and hence facilitate the expulsion of waxy oil that is generated from matrix liptinite

oxygen isotopes of marine diatoms and relations to opal a maturation in order to develop the potential tool of diatom oxygen isotopes for paleoenvironmental studies we compared oxygen isotopes of natural marine diatoms sampled from ocean surface water sediment traps and surface sediments with oxygen isotopic fractionations determined for laboratory diatom cultures freshly grown natural diatoms phytoplankton samples and sediment trap material and cultured diatoms reveal similar oxygen isotope fractionation factors the fresh diatoms have 3 to 10 parts per thousand lower isotope fractionation factors than fossil sedimentary diatoms a temperature related oxygen isotope fractionation could not be established for the laboratory cultures and the natural phytoplankton samples and there is evidence that diatom growth rate until reaching the stationary growth state also controls the measured silica water oxygen isotope fractionation factor it is possible however that slow diatom growth in sea surface water may well lead to a temperature dependent silica water oxygen isotope fractionation which is the prerequisite for a use of diatom oxygen isotopes in palco surface water studies ftir spectroscopic analyses of various diatomaceous materials revealed that the ratio of integrated peak intensities for si o si si oh correlates with the 3 to 10 parts per thousand delta o 18 silica increase from fresh to fossil diatoms open system flow through silica dissolution experiments suggest that the diatom frustules are isotopically homogenous and that the increase in o 18 is therefore not due to dissolution of isotopically light surficial si oh groups it is concluded that slow internal condensation reactions during silica maturation in surface sediments cause both an increase in the intensity ratio of si o si si oh and the o 18 content of framework oxygen these findings also indicate that the oxygen isotope compositions of marine sediment diatoms do not indicate sea surface water temperature but rather reflect variable o 18 contents of surface sediments copyright c 2001 elsevier science ltd

effects of thermal maturation on stable organic carbon isotopes as determined by hydrous pyrolysis of woodford shale acquiring crude oils that have been expelled from the same rock unit at different levels of thermal maturation is currently not feasible in the natural system this prevents direct correlation of compositional changes between the organic matter retained in a source rock and its expelled crude oil at different levels of thermal maturation alleviation of this deficiency in studying the natural system requires the use of laboratory experiments natural generation of petroleum from amorphous type ii kerogen in the woodford shale may be simulated by hydrous pyrolysis which involves heating crushed rock in contact with water at subcritical temperatures 374 c four distinct stages of petroleum generation are observed from this type of pyrolysis 1 pre oil generation 2 incipient oil generation 3 primary oil generation and 4 post oil generation the effects of thermal maturation on the 13c values of kerogen bitumen and expelled oil like pyrolysate from the woodford shale have been studied through these four stages of petroleum generation similar to the natural system the kerogens isolated from the pyrolyzed rock showed no significant change in 13c this suggests that the 13c value of kerogens may be useful in kerogen typing and oil to source rock correlations 13c values of bitumens extracted from the pyrolyzed rock showed an initial decrease during the incipient oil generation stage followed by depletion during the primary and post oil generation stages this reversal is not favorable for geochemical correlation or maturity evaluation saturated and polar components of the bitumen show the greatest 13c variations with increasing thermal maturation the difference between the 13c of these two components gives a unidirectional trend that serves as a general indicator of thermal maturation and is referred to as the bitumen isotope index bii 13c values of the expelled pyrolysates show a unidirectional increase with increasing thermal maturation the constancy and similarity of 13c values of the aromatic components in the expelled pyrolysates and bitumens with increasing thermal maturation encourages their use in oil to oil and oil to source rock correlations isotopic type curves for expelled pyrolysates indicate that they may be useful in oil to oil correlations but have a limited use in oil to source rock correlations

higher plant biomarker signatures of early eocene sediments of north eastern india abstract the biomarkers molecular fossils of paleobiota have been studied in detail from a coal bearing sequence of early eocene lakadong sandstone member of sylhet formation of upper assam basin ne india using gas chromatography mass spectrometry corresponding hydrocarbon source potential of the same unit has been studied using rock eval pyrolysis the rock eval data suggest dominant terrestrial land plant contribution i e type iii kerogen and the sediments of the section had entered the early stage of catagenesis the alkane and isoprenoid distributions are characterized by odd over even preference oep 1 1 1 2 of n alkanes and high pristane phytane ratio 2 9 7 6 which corroborate the rock eval data the distribution of aliphatic biomarkers is characterized by dominance of c24 tetracyclics over c23 tricyclics high concentration of des e hopane moderate to high c29 c30 hopane ratio extremely low oleanane index and low c35 homohopane index the extremely low oleanane index is correlated with a high degree of aromatization of oleanane skeleton favoured by acidic swampy depositional environment the presence of diterpanes at the base of the early eocene section indicates contribution from gymnosperms coniferales order of land plants whereas angiospermous biomarkers with oleanoid skeleton are also preserved this pattern subsequently evolved to angiosperm dominated towards the top of the section with no gymnosperm signature indicating possible climatic variation during the early eocene towards the top of the section presence of bicadinanes indicates contribution of dipterocarpaceae family of trees and advent of the evergreen tropical rain forest element in eastern india in early eocene similar to the pattern found in western india e g cambay and kutch basins

organic matter provenance and depositional environment of marine to continental mudstones and coals in eastern ordos basin china evidence from molecular geochemistry and petrology abstract cyclothems composed of interbedded mudstone coal and sandstone layers make up the taiyuan and shanxi formations in the late carboniferous to early permian in north china under a marine to continental depositional environment the cyclothems act as important fossil energy hosts such as coalbeds hydrocarbon source rocks and unconventional natural gas reservoirs organic geochemistry and petrology of mudstones and coals in the taiyuan and shanxi formations in the eastern ordos basin were studied to reveal the organic matter sources and paleoenvironments total organic carbon toc contents vary from 1 1 wt mudstone to 72 6 wt coal the samples are mainly within the oil window with the tmax values ranging from 433 to 469 c organic petrology and source biomarkers indicate that the mudstones were sourced from a mixed organic matter input and terrigenous organic matter predominates over aquatic organic matter the coals are mostly sourced by terrigenous organic matter inputs high concentrations of hopanes argue for a strong bacterial input some m z 217 mass chromatograms have peaks at the hopanes retention times as a result of high hopane to sterane ratios these hopane derived peaks do not interfere the identification of the steranes because the hopanes and the steranes have different retention times maturity dependent biomarkers demonstrate that the samples have been thermally mature which agree with the tmax values anomalously low c29 20s 20s 20r and c29 sterane ratios are present in all the samples and are interpreted as due to the terrigenous organic matter input or the coal related depositional environment in addition biomarkers and iron sulfide morphology indicate that the organic matter of the mudstones deposited in a proximal setting with shallow brackish fresh water bodies with consideration of preservation of organic matter the redox conditions are dysoxic redox oscillations resulted in the records of oxic conditions in some samples finally the coals and the mudstones mainly generate gas and have poor oil generative potential

petrological palynological and geochemical characteristics of eureka sound group coals stenkul fiord southern ellesmere island arctic canada abstract late paleocene early eocene coal bearing strata are widespread across the canadian arctic archipelago laterally continuous seams of substantial thickness are present in the iceberg bay formation eureka sound group at stenkul fiord ellesmere island sixty four coal seams with a cumulative thickness of 53 m of coal occur in a 450 m sequence the investigation of the composite section is based on examination of 19 samples from seams thicker than 1 m and 7 samples from marker seams used for correlation purposes the coals consist predominantly of wood derived huminite macerals 79 98 vol structured huminite macerals are dominant in the top part of the section whereas detrital components are abundant in the lower part the liptinite fraction is dominated by sporinite and cutinite 1 9 vol inertinite content is very low except at the base of the section 0 14 vol reflectances determined on eu ulminite 0 36 0 43 r o geochemical parameters and thermal alteration indices indicate that the coals are of lignite to subbituminous rank the dominance of diterpanes and the abundance of taxodiaceae and pinaceae pollen suggest that most of the organic matter is of gymnospermous origin pinaceae pollen is abundant in the lower part of the section and taxodiaceae is abundant in the upper part the abundance of angiosperm pollen in most of the section suggests however that angiospermous plants were significant members of the flora the depositional environment for the iceberg bay formation coals at stenkul fiord is that of forested swamps on an alluvial plain pollen assemblages indicate a late paleocene early eocene age for the section and a temperate moist climate