core evidence of paleoseismic events in paleogene deposits of the shulu sag in the bohai bay basin east china and their petroleum geologic significance abstract the shulu sag located in the southwestern corner of the jizhong depression bohai bay basin of east china is a ne sw trending elongate cenozoic half graben basin the lowermost part of the third member of the shahejie formation in this basin is characterized by continental rudstone and calcilutite to calcisiltite facies based on core observation and regional geologic analysis seismites are recognized in these lacustrine deposits which include soft sediment deformation structures sedimentary dikes hydraulic shattering diapir structures convolute lamination load flame structures ball and pillow structures loop bedding and subsidence structures synsedimentary faults and seismoturbidites in addition mixed source rudstones consisting of the paleozoic carbonate clasts and in situ calcilutite clasts in the lowermost submember of shahejie 3 appear in the seismites suggesting an earthquake origin a complete representative vertical sequence in the lowermost part of the third member found in well st1h located in the central part of the shulu sag shows from the base to the top underlying undeformed layers synsedimentary faults liquefied carbonate rocks allogenetic seismoturbidites and overlying undeformed layers seismites are widely distributed around this well and there are multiple sets of stacked seismites separated by undeformed sediment the nearby nw trending taijiazhuang fault whose fault growth index is from 1 1 to 1 8 and the nne trending xinhe fault with a fault growth index of 1 3 1 9 may be the source of the instability to create the seismites these deformed sedimentary layers are favorable for the accumulation of oil and gas for example sedimentary dikes can cut through many layers and serve as conduits for fluid migration sedimentary faults and fractures induced by earthquakes can act as oil and gas migration channels or store petroleum products as well seismoturbidites and mixed source rudstones are excellent reservoirs due to their abundant primary or dissolved pores

the guadalupian permian kamura event in european tethys article i nfo in order to document paleoenvironmental conditions of the equatorial western paleo tethys during the late middle permian prior to the end guadalupian mass extinction chemostratigraphic analysis using stable carbon isotopes was conducted for the guadalupian rocks at brusane in the velebit mtn central croatia by analyzing 72 carbonate samples of the capitanian upper guadalupian velebit formation we found an interval with unusually high 13 ccarb values 4 to 6 in the ca 150 m thick yabeina fusuline zone the present find clarifies that the primary productivity and burial rate into the sediments were considerably high during the capitanian in westernmost paleo tethys this chemostratigraphic signal is properly correlated with the kamura event detected in a mid panthalassan paleo atoll limestone in japan the present results identify the capitanian kamura event for the first time in european paleo tethys on the opposite side of the globe from the mid panthalassan paleo seamount and prove the global context of the event as well as its utility in chemostratigraphic correlation in order to enhance bioproductivity on a global scale the increase in nutrient supply is inevitable in addition to riverine run off from pangea active oceanic circulation in particular upwelling of deep sea water enriched in nutrients was likely vital both in panthalassa and paleo tethys the extinction of some guadalupian fauna in particular photosymbiotic community large tested fusulines large bivalves rugose corals was likely related to a temporary cooling coupled with eutrophication in low latitude shallow marine environments of paleo tethys and panthalassa

the occurrence of giant bivalve alatoconchidae from the yabeina zone upper guadalupian permian in european tethys abstract the permian gigantic bivalve family alatoconchidae forms a member of the tropical shallow marine fauna intimately associated with the tethyan warm water adapted verbeekinidae fusulines such as neoschwagerina and yabeina the velebit mountains in central croatia is one of the nine areas in the world that yielded alatoconchidae as first reported early in the 1970 s in addition to the neoschwagerina zone wordian middle guadalupian originally described we newly found alatoconchidae from the yabeina zone capitanian upper guadalupian from the brusane area in the central velebit mountains alatoconchidae occur in three stratigraphic levels of the velebit formation composed of black fusuline algal wackestone packstone with yabeina although fragmented the alatoconchidae shell reach sizes over 40 cm long and possess unique morphology with a lateral flange plus a prominent prismatic external layer in the double layered shell structure our results confirm for the first time in europe and thus in the western tethyan domain that the stratigraphic range of the gigantic bivalve family extends up to the capitanian as well as in the superocean panthalassa as no occurrence has been reported from the overlying lopingian upper permian alatoconchidae likely became extinct globally at the end of the guadalupian i e through the guadalupian lopingian boundary mass extinction

stable isotope and trace element stratigraphy across the permian triassic transition a redefinition of the boundary in the velebit mountain croatia article i nfo stable isotopes of carbonates 13 ccarb 18 ocarb organic matter 13 corg 15 norg and major trace and rare earth element ree compositions of marine carbonate rocks of late permian to early triassic age were used to establish the position of the permian triassic boundary ptb at two continuous sections in the velebit mountain croatia the chosen sections rizvanusa and brezimenjaca are composed of two lithostratigraphic units the upper permian transitional dolomite and the overlying sandy dolomite the contact between these units characterized by the erosional features and sudden occurrence of ooids and siliciclastic grains was previously considered as the chronostratigraphic ptb the sandy dolomite is characterized by high content of non carbonate material up to 30 wt insoluble residue originated from erosion of the uplifted hinterland a relatively rich assemblage of permian fossils including geinitzina globivalvulina hemigordius b ioclasts of gastropods ostracods and brachiopods was found for the first time in sandy dolomite 5 m above the lithologic boundary in the rizvanusa section a rather abrupt negative 13 ccarb excursion in both sections appears in rocks showing no recognizable facies change within the sandy dolomite 2 at rizvanus aa nd 1 2 at brezimenjaca 11 m and 0 2 m above the lithologic contact respectively this level within the lower part of the sandy dolomite is proposed as the chemostratigraphic ptb in the rizvanus as ection the 13 corg values decline gradually from 25 in the upper permian to 29 in the lower triassic the first negative 13 corg

thermal history of the central part of the karst dinarides croatia combined application of clay mineralogy and low t thermochronology this study was undertaken to unravel the thermal history values timing and origin of the maximum palaeotemperatures rates of exhumation of the c

generation of gas and oil from coal and other terrestrial organic matter abstract late carboniferous permian sedimentary rocks contain the world s largest coal reserves which have generated and released gas but little if any oil in comparison organic matter deposited in lacustrine fluvial deltaic or brackish water sediments has sourced large quantities of waxy oils in countries such as china australia the u s a argentina venezuela and indonesia plus gas and condensate in deltas worldwide why is more oil coming from land derived organic matter disseminated in sediments than from the carboniferous permian coal beds which also are land deposits the answer appears to be in the hydrogen content and the ease of migration when organic matter and coals have high hydrogen contents relative to carbon they can form oil when the hydrogen is low mainly gas is formed most of the world s coal is low in hydrogen whereas much of the terrestrial organic matter disseminated in sediments is higher in hydrogen so it forms more oil also both gas and oil are adsorbed on coal more strongly than on the disseminated kerogen of sedimentary rocks this makes migration of oil out of the coal more difficult compared to migration from conventional shale source rocks

source rock characterization and oil generating potential of the jurassic madbi formation onshore east shabowah oilfields republic of yemen abstract the hydrocarbon source rock potential of shales from the jurassic madbi formation was evaluated using organic geochemistry rock eval pyrolysis toc and bitumen extraction and organic petrology very good source rock potential is suggested by high values of total organic carbon content toc 2 0 wt and high extractable organic matter content and hydrocarbon yields 11 000 and 6000 ppm respectively the madbi formation samples have high hydrogen index hi and low oxygen index oi values most of the samples in the study area are thermally mature and contain oil prone type i and type ii kerogen vitrinite reflectance ro values for the madbi shale samples were measured from 0 74 to 0 89 tmax values range from 430 to 438 c which are in reasonably good agreement with vitrinite reflectance data reveal that the madbi shales are at the early to peak mature stage on the basis of biomarker maturity parameters these shales are thermally mature shales of the madbi formation contain abundant hydrogen rich kerogen liptinite up to 55 and therefore good oil generating potential is anticipated this is supported by high hydrogen indices hi of up to 400 mg hc g toc and early to peak mature oil window range

source rock characteristics and hydrocarbon generation modelling of upper cretaceous mukalla formation in the jiza qamar basin eastern yemen abstract the upper cretaceous mukalla coals and other organic rich sediments which are widely exposed in the jiza qamar basin and believed to be a major source rocks were analysed using organic geochemistry and petrology the total organic carbon toc contents of the mukalla source rocks range from 0 72 to 79 90 with an average toc value of 21 50 the coals and coaly shale sediments are relatively higher in organic richness consistent with source rocks generative potential the samples analysed have vitrinite reflectance in the range of 0 84 1 10 ro and pyrolysis t max in the range of 432 454 c indicate that the mukalla source rocks contain mature to late mature organic matter good oil generating potential is anticipated from the coals and coaly shale sediments with high hydrogen indices 250 449 mg hc g toc this is supported by their significant amounts of oil liptinite macerals are present in these coals and coaly shale sediments and py gc s 2 pyrograms with n alkane alkene doublets extending beyond nc 30 the shales are dominated by type iii kerogen hi one dimensional basin modelling was performed to analysis the hydrocarbon generation and expulsion history of the mukalla source rocks in the jiza qamar basin based on the reconstruction of the burial thermal maturity histories in order to improve our understanding of the of hydrocarbon generation potential of the mukalla source rocks calibration of the model with measured vitrinite reflectance ro and borehole temperature data indicates that the present day heat flow in the jiza qamar basin varies from 45 0 mw m 2 to 70 0 mw m 2 and the paleo heat flow increased from 80 ma to 25 ma reached a peak heat flow values of approximately 70 0 mw m 2 at 25 ma and then decreased exponentially from 25 ma to present day the peak paleo heat flow is explained by the gulf of aden and red sea tertiary rifting during oligocene middle miocene which has a considerable influence on the thermal maturity of the mukalla source rocks the source rocks of the mukalla formation are presently in a stage of oil and condensate generation with maturity from 0 50 to 1 10 ro oil generation 0 5 ro in the mukalla source rocks began from about 61 ma to 54 ma and the peak hydrocarbon generation 1 0 ro occurred approximately from 25 ma to 20 ma the modelled hydrocarbon expulsion evolution suggested that the timing of hydrocarbon expulsion from the mukalla source rocks began from 15 ma to present day

the genesis of coal from the viewpoint of coal petrology abstract the genesis of the microscopic constituents of coal macerals and of maceral associations microlithotypes representing various coal facies is discussed in the light of recent advances that have been made in the study of coals and modern peats peat microscopy especially promoted the understanding of humification and biological gelification both of which are decisive for the genesis of huminites vitrinites in brown coals and hard coals respectively microbial activity during peatification has been documented by chemists microbiologists and petrologists and recently by electron microscopical observations in coals this activity leads to the incorporation of lipid substances into the humic matter and later influences the chemical physical and technological properties of vitrinites geochemical gelification transforms the huminites of brown coals into the vitrinites of bituminous coals and is probably caused by the onset of bitumen generation in coal in this process the hydrogel brown coal is transformed to the bitumogel bituminous coal coal as a source rock for oil has become an important research subject for coal petrologists and oil exploration the formation of more or less liquid bitumen and its later cracking to gaseous hydrocarbons leads to the coalification jumps of the macerals especially liptinites and vitrinites and to the generation of secondary macerals like exsudatinite bitumen and micrinite dead carbon bituminization in coal has been revealed by the use of fluorescence microscopy which also found the presence of new liptinite macerals bituminite fluorinite and exsudatinite and suggests a higher proportion of algal material in coals than was thought earlier the genesis of various types of inertinite macerals will probably become an increasingly important subject of research especially with regard to rank inertinites that seem to attain their high inertinitic reflectance initially during coalification besides the origin of macerals the origin of various coal facies in terms of maceral associations is considered in relation to the palaeogeographic depositional milieu the peat forming vegetation palaeoclimate water and nutrient supply acidity marine and calcareous influence and fire with examples from euramerican carboniferous coals gondwana coals and tertiary brown coals vegetation water and oxygen supply eh conditions are most important for the generation of coal facies vegetation has been reconstructed with the help of palaeobotany including palynology cuticular analysis and wood anatomy in brown coals and with the study of petrified permineralized peats preserved in coal balls the microscopical investigations of botanically recognizable plant remains isolated from coals or accompanying rocks has been especially informative however the results of palynological and cuticular analyses should be evaluated with caution considering the varying resistance of palynomorphs and cuticles and in the case of palynomorphs their possible extrapaludal origin microscopical studies of modern peats that were derived from different types of vegetation growing in different hydrological environments have been very helpful in interpreting coal facies especially in brown coals the much disputed origin of brown coal lithotypes is considered in detail for hard coals there seems to be agreement that coal layers rich in vitrites and liptinite poor clarite were deposited in wet forest swamps that microlayered liptinite rich clarites are sub aquatic humic muds and that inertinite rich durites represent oxidized peats the origin of liptinite rich durites is controversial either subaquatic muds or oxidized peats the latter perhaps from raised bogs a recent trend in the literature is the assumption that many if not all mineable coal seams have been deposited in raised bogs under ombrogenous oligotrophic conditions although raised bogs with a dense arborescent vegetation are known from borneo it seems not probable that most seams which were deposited in foredeeps or steadily sinking graben zones are of ombrogenous origin although a succession from relatively wet and eutrophic to relatively dry and oligotrophic conditions may be true for occasional seams but as in modern peats striking changes of coal facies are commonly caused by hydrological events e g inundations as a consequences of crevasses or of fires that burned the peat the origin of the inertinite rich gondwana coals is discussed in relation to their specific climatic conditions and a comparison with sub arctic peats is recommended coals influenced by marine and calcareous conditions are characterized by high contents of sulfur and pyrite as well as by hydrogen rich vitrinites with a relatively low reflectance and high fluorescence all due to a strong bacterial activity in peats of low acidity proposals for further research are made in the conclusions

tertiary stratigraphy and basin evolution southern sabah malaysian borneo abstract new mapping and dating of strata in the southern part of the central sabah basin in northern borneo has made it possible to revise the lithostratigraphy and chronostratigraphy of the area the recognition in the field of an early miocene regional unconformity which may be equivalent to the deep regional unconformity recognised offshore has allowed the development of a stratigraphic framework of groups and formations which correspond to stages in the sedimentary basin development of the area below the early miocene unconformity lies ophiolitic basement which is overlain by an accretionary complex of eocene age and a late paleogene deep water succession which formed in a fore arc basin the late paleogene deposits underwent syn depositional deformation including the development of extensive melanges all of which can be demonstrated to lie below the unconformity in this area some localised limestone deposition occurred during a period of uplift and erosion in the early miocene following which there was an influx of clastic sediments deposited in delta and pro deltaic environments in the middle miocene these deltaic to shallow marine deposits are now recognised as forming two coarsening upward successions mapped as the tanjong and kapilit formations the total thickness of these two formations in the central sabah basin amounts to 6000 m only half of the previous estimates although the total stratigraphic thickness of cenozoic clastic strata in sabah may be more than 20 000 m

palaeoceanography and biogeography in the early jurassic panthalassa and tethys oceans abstract a first conceptual palaeoceanographic model for the early jurassic panthalassa and tethys oceans is outlined in the present paper the new palaeoceanographic model uses fundamental physic oceanographic principles known from the modern world and a global palaeogeographic reconstruction for the early jurassic to examine the long term response of the panthalassic and tethyan fossil invertebrate faunas to the proposed surface ocean circulation analysis of palaeobiogeographical data ostracods ammonites brachiopods and bivalves has enabled circulation changes to be reconstructed over the studied period in some detail panthalassic circulation pattern shows an almost hemispherical symmetric pattern with the development of the two large subtropical gyres that rotates clockwise in the northern hemisphere and anti clockwise in the southern hemisphere surface circulation in the tethyan ocean is dominated by monsoonal westerly directed equatorial surface currents that reached its western corner and droved them off to the north along the northern side of the tethys ocean during summer and in opposite direction during the winter

rock eval tmax suppression documentation and amelioration the rock eval thermal maturation parameter tmax may occasionally be suppressed relative to surrounding rock units this is commonly assumed to result from either a bitumen contribution to the s2 peak or the presence of sulfur rich and hence thermally labile kerogen the phenomenon is frequently coincident with a high natural gamma ray signature and elevated rock eval hydrogen index hi and total organic carbon toc contents determination of thermal maturity of such units relies either on the interpolation of tmax from surrounding units or the direct estimation of the extent of suppression on a given sample the latter may be required if the available samples are restricted to conventional or sidewall core material representative of imited stratigraphic intervals the second white speckled shale part of the cretaceous colorado group in the alberta basin displays tmax suppression over part of its thickness a consistent relationship emerges from calculating a linear regression of tmax as a function of either toc or hi for several wells at different levels of thermal maturity below values of about 453 c late oil window tmax is suppressed by about 1 c for every increase in hi of 50 mg hydrocarbon g toc thus tmax suppression in the second white speckled shale can be corrected by extrapolating all tmax values to a constant hi of 100 to 150 mg hydrocarbon g toc values typical of type iii kerogen

petrological and geochemical characterization of candiota coal seams brazil implication for coal facies interpretations and coal rank abstract seven coal seams from cores of the borehole m iv c 101 candiota coalfield located in rio grande do sul state southern part of the parana basin were analyzed by coal petrographical and organic geochemical methods the seams occur in the rio bonito formation guata group tubarao supergroup of the parana basin and are of permian artinskian kungurian age the composition rank coal facies and depositional environment characterization were made based on lithotype maceral and microlithotype analyses the data were then used in the definition of different types of facies critical petrographical indices and were displayed in diagrams of coal facies in addition coal seams samples from candiota mine were analyzed by proximate total moisture and gross calorific values and were classified using the united nations economic commission for europe un ece classification in addition rock eval pyrolysis liquid chromatography gc and gc ms analyses were made to obtain independent parameters on coal rank and organic matter composition and environment of deposition the results suggest deposition in open mires with elevated contents of detrital macerals and clay minerals and also limno telmatic coal facies coal bearing sequence of coal seams represent a back barrier setting according to the international classification un ece candiota coals are in the subbituminous or low rank coal a stage results from geochemical analyses showed that terrestrial organic matter is predominant as indicated by hydrogen and oxygen indices carbon preference indices and the sterane distribution geochemical maturity parameters such as the 20 s 20 s 20 r and ratios for c 29 regular steranes support the low level of rank maturity as indicated by the vitrinite reflectance measurements 0 41 0 45 and gross calorific values

uncertainty in wellhead protection area delineation due to uncertainty in aquifer parameter values abstract the importance of modeling in hydrogeologic investigations has been stressed in a number of studies since the applicability of any model is dependent on the type of need and availability of hydrogeological information a parametric analysis is essential to determine its applicability this paper presents the results of a parametric analysis conducted to evaluate the effect of data uncertainty on wellhead protection area whpa delineation the precision of aquifer parameter values is the most important factor in a whpa delineation process in relation to the model itself to demonstrate the effect of variable values in a wellfield we tested modified version of time related analytical groundwater flow concept using a ressqc model which is used for capture zone delineation and to delineate contaminant front for injection wells the ressqc model is a modified version of the ressq code which was initially designed to only delineate contaminant fronts for injection wells field measured aquifer parameters for a shallow aquifer were used in the analysis the results indicate that great caution must be taken when aquifer parameters such as hydraulic gradient thickness transmissivity and porosity are being used for whpa delineation since over or under protection of whpa can jeopardize the public health an extended aquifer test and installation of various observation wells in or near different lithologic and depth zones may increase reliability of parameter values

variations in the geochemistry of closely interbedded oil prone coals and shales paralic and deltaic environments frequently contain closely interbedded oil prone coals and carbonaceous shales of similar organic facies however differences in depositional and diagenetic conditions can result in significant variations in geochemistry between these coals and shales these variations are observed in sediments from a range of ages and areas including australia new zealand and indonesia for example pristane phytane and pristane n c sub 17 ratios are frequently higher in coals than in associated shales although n alkane distributions are similar the c sub 27 ts tm ratios are frequently much lower in coals although most other biomarker ratios are generally the same for coals and shales however absolute biomarker concentrations particularly of c sub 27 tm hopane can be two to four times higher in coals significantly many coals contain high concentrations of diasteranes equivalent to those observed in shales differences in other parameters such as the c sub 30 diahopane c sub 30 hopane ratios and pyrolysate compositions are also evident data indicate that rocks begin to become more coal like at tocs of approximately 25 the variations in these parameters are probably the result of variability in early depositional and diagenetic conditions such as eh ph and microbial action in addition these parameters are probably influenced by the effectsmore of an organic vs an inorganic matrix the impact of this variability must be considered when conducting oil source correlation studies and when assessing the relative contributions of coals and shales to the generation of oil in a basin less

organic geochemical characteristics and depositional environments of the jurassic coals in the eastern taurus of southern turkey abstract in this study organic matter content type and maturity as well as some petrographic and physical characteristics of the jurassic coals exposed in the eastern taurus were investigated and their depositional environments were interpreted the total organic carbon toc contents of coals in the feke akkaya kozan gedikli and kozan kizilinc areas are 24 54 66 78 and 49 15 respectively the feke akkaya and kozan kizilinc coals have low hydrogen index hi values while the kozan gedikli coals show moderate hi values all coal samples display very low oxygen index oi values the kozan gedikli coals contain type ii organic matter om the feke akkaya coals contain a mixture of type ii and type iii om and the kozan kizilinc coals are composed of type iii om sterane distribution was calculated as c27 c29 c28 from the m z 217 mass chromatogram for all coal samples tmax values for the feke akkaya kozan gedikli and kozan kizilinc coals are 439 412 and 427 c vitrinite reflectance values ro for the feke akkaya and kozan kizilinc coal samples were measured as 0 65 and 0 51 and these values reveal that the feke akkaya and kozan kizilinc coals are at subbituminous a or high volatile c bituminous coal stage on the basis of biomarker maturity parameters these coals have a low maturity the pristane phytane pr ph ratios for the feke akkaya kozan gedikli and kozan kizilinc coals are 1 53 1 13 and 1 25 respectively in addition all coals show a homohopane distribution which is dominated by low carbon numbers and c35 homohopane index is very low for all coal samples all these features may indicate that these coals were deposited in a suboxic environment the high sterane hopane ratios with high concentrations of steranes low pr ph ratios and c25 c26 tricyclic ratios 1 may indicate that these coals formed in a swamp environment were temporarily influenced by marine conditions

organic geochemical characteristics and depositional environment of the tertiary tanjong formation coals in the pinangah area onshore sabah malaysia article i nfo article history the tertiary tanjong formation coals exposed in the west middle block of the pinangah coalfield central part of southern sabah were analyzed and their depositional environments were interpreted the tertiary tanjong coals are humic and generally dominated by vitrinite with significant amounts of liptinite and low amounts of inertinite macerals total organic carbon contents toc of the coals range from 51 2 to 77 7 wt and yield of bitumen values ranging from 57 300 to 140 000 ppm which meet the standard as a source rock with good hydrocarbon generative potential in support good liquid hydrocarbons generation potential can be expected from the tanjong coals based on significant liptinitic content 15 this is supported by their high hydrogen index up to 300 mg hc g toc consistent with type ii and mixed type ii iii kerogens and py gc s2 pyrograms with n alkane alkene doublets extending beyond c30 the coal samples have vitrinite reflectance values in the range of 0 42 0 66 ro indicating immature to early mature stage for hydrocarbon generation these vitrinite reflectance values also indicated that the tanjong coals are with sub bituminous b a and high volatile bituminous c rank tmax values ranging from 419 to 451 c are good agreement with the vitrinite reflectance data this is supported by biomarker maturity parameters as suggested by the c32 homohopane the saturated fraction of the tanjong coals are characterized by dominant odd carbon numbered n alkanes n c23 to n c33 high pr ph ratios 8 18 high tm ts ratios 6 28 and pre dominant of regular sterane c29 all biomarker parameters clearly indicate that the organic matter was de rived from terrestrial inputs and deposited under oxic condition

generation and expulsion of oils from permian coals of the sydney basin australia abstract organic geochemical and petrological assessment of coals coaly shales and fine grained sediments coupled with organic geochemical analyses of oil samples all from permo triassic sections of the southern sydney basin australia have enabled identification of the source for the widely distributed oil shows and oil seeps in this region the permian coals have higher hydrogen indices higher liptinite contents and much higher total organic matter extract yields than the fine grained sediments a variety of source specific parameters obtained from n alkanes regular isoprenoids terpanes steranes and diasteranes indicate that the oil shows and seeps were generated and expelled predominantly from higher plant derived organic matter deposited in oxic environments the source and maturity related biomarkers and aromatic hydrocarbon distributions of the oils are similar to those of the coals the oil coal relationship also is demonstrated by similarities in the carbon isotopic composition of the total oils coal extracts and their individual n alkanes extracts from the permo triassic fine grained sediments on the other hand have organic geochemical signatures indicative of mixed terrestrial and prokaryotic organic matter deposited in suboxic environments which are significantly different from both the oils and coal extracts the molecular signatures indicating the presence of prokaryotic organic matter in some of the coal extracts and oils may be due to thin sections of possibly calcareous lithologies interbedded within the coal measures the genetic relationship between the oils and coals provides new evidence for the generation and expulsion of oils from the permian coals and raises the possibility for commercial oil accumulations in the permian and early triassic sandstones potentially in the deeper offshore part of the sydney basin

geology and geochemistry of pachmarhi dykes and sills satpura gondwana basin central india problems of dyke sill flow correlations in the deccan traps many tholeiitic dyke sill intrusions of the late cretaceous deccan traps continental flood basalt province are exposed in the satpura gondwana basin around pachmarhi central india we present field petrographic major and trace element and sr nd pb isotope data on these intrusions and identify individual dykes and sills that chemically closely match several stratigraphically defined formations in the southwestern deccan western ghats some of these formations have also been identified more recently in the northern and northeastern deccan however the pachmarhi intrusions are significantly more evolved lower mg numbers and higher tio2 contents than many deccan basalts with isotopic signatures generally different from those of the chemically similar lava formations indicating that most are not feeders to previously characterized flows they appear to be products of mixing between deccan basalt magmas and partial melts of precambrian indian amphibolites as proposed previously for several deccan basalt lavas of the lower western ghats stratigraphy broad chemical and isotopic similarities of several pachmarhi intrusions to the northern and northeastern deccan lavas indicate petrogenetic relationships distances these lava flows would have had to cover if they originated in the pachmarhi area range from 150 to 350 km the pachmarhi data enlarge the hitherto known chemical and isotopic range of the deccan flood basalt magmas this study highlights the problems and ambiguities in dyke sill flow correlations even with extensive geochemical fingerprinting

organic facies and depositional palaeoenvironment of lignites from rio maior basin portugal abstract the rio maior basin portugal is a tectonic depression filled by a pliocene sequence that comprises from floor to roof i kaoliniferous fine sands ii diatomites and lignites iii recent deposits of sandstone and clay the diatomites and lignites form a small dissimetric syncline with alternating seams ten lignite seams were identified and named from floor to roof as f e d c 2 c 1 c b a a and a seams a d e and f are considered to be the main seams the organic fraction consists mainly of macerals of the huminite group with small percentages of inertinite and liptinite groups however the petrographic composition of each seam is distinct particularly with regards to macerals of the huminite and liptinite groups calculation of petrographic indices permitted to plot the coals in facies and palaeoenvironment diagrams five facies have been defined i aquatic ii herbaceous swamp iii mixed swamp with forest and herbaceous vegetation vi forest swamp wetter and v forest swamp drier these lignites are humic coals formed from organic matter of terrestrial origin the peat biomass at the origin of these coals formed from a very diverse vegetation comprising gymnosperms and angiosperms in seams f and occasionally in seams e and d botryococcus algae have also contributed to the biomass peat deposition corresponded to a rheotrophic hydrological regime the water level always remained above the topographic surface of the basin nevertheless during the deposition of seam a in the northern part of the basin the water level was slightly below the topographic surface the organic matter was preserved in anaeorobic conditions

ecologic and taxonomic diversification in the mesozoic brackish water bivalve faunas in japan with emphasis on infaunalization of heterodonts abstract mesozoic brackish water bivalve faunas in japan diversified in three steps at the beginning of the early jurassic early and late cretaceous the hettangian niranohama fauna in northeastern honshu represents the establishment of a heterodont dominated brackish water fauna that persisted until the early late cretaceous no similar composition is known from the triassic the infauna consists mostly of non siphonate and some short siphonate heterodonts while the epifauna is represented by diverse pteriomorphian families in the early cretaceous tetori group in central honshu the long siphonate heterodonts tetoria corbiculidae and the semi infaunal soft bottom oyster crassostrea appeared the evolutionary diversification of the latter known as the most important element of modern brackish water faunas may thus originate at that time in the early late cretaceous cenomanian of the goshoura and mifune groups in west kyushu several euryhaline deep burrowing heterodont families such as veneridae and tellinidae further diversified in the brackish and marine environments the late cretaceous is characterized by massive shell biolithic beds in which large crassostrea species are common a feature common for cenozoic brackish water faunas the long term changes in the composition of the brackish water faunas in japan represents thus an evolutionary record irrespective of the severe physiological and environmental conditions imposed on the highly conservative nature of the fauna

organic facies and maturation of jurassic cretaceous rocks and possible oil source rock correlation based on pyrolysis of asphaltenes scotian basin canada abstract this paper establishes source rock characterization and oil oil and oil source rock correlations of selected organic rich shale source rocks and selected light oils and condensates from jurassic and cretaceous formations of the scotian basin multiple source rocks of kerogen types iia oil prone iia iib oil and condensate prone iib condensate and gas prone iii gas prone and iv nonsource are identified in various stratigraphic horizons vitrinite reflectance and t inmax data indicate variable maturation histories in different parts of the basin which are related to differences in lithology related heat conductivity and the presence of older sediments closer to areas of rifting multiple linear regression and cluster analyses of aromatic hydrocarbon ratios reveal two oil families some kerogen type iib rock extracts match many of the light oil and condensates in terms of the aromatic hydrocarbon distributions a second family of oils could not be correlated with any of the analyzed source rock extracts pyrolysis gas chromatography of asphaltenes from the cohasset a 52 and sable island 3h 58 wells are significantly different in n alkane aromatics and phenol content the asphaltene pyrolyzates of samples from venture b 52 and s desbarres o 76 have a high aromatic content low content of n alkanes and high phenol values s desbarres which is typical of a terrestial source they correlate well with one another and also with sable island light oil the n triumph g 43 whole rock and extract asphaltene pyrolyzates are dominated by normal hydrocarbons with aromatic phenolic and thiophenic compounds in low concentrations suggesting an algal source algal type organic matter may have made a contribution to the cohasset petroleum as its asphaltene pyrolyzate is also dominated by normal hydrocarbons

well catchments and time of travel zones in aquifers with recharge the classical analytical method used to map catchments and time of travel zones of pumping wells was originally derived for another purpose and takes no account of recharge bear and jacobs 1965 generalized catchment shapes are presented here for aquifers with recharge they can be scaled to field situations through two or three nondimensional parameters a semianalytical path line tracing model was used to generate the shapes it contains new expressions for pore water velocities in two infinite strip recharged aquifers one with two fixed head boundaries the other with one impermeable boundary the resulting catchments differ significantly in both shape and size from catchments estimated by the no recharge method generalized results are also presented for time of travel zones which are noticeably smaller than those calculated by the no recharge method comparison with an equivalent recently released model from the u s environmental protection agency shows the latter to give poor estimates of catchments and time of travel zones

major and trace element geochemistry of the lacustrine organic rich shales from the upper triassic chang 7 member in the southwestern ordos basin china implications for paleoenvironment and organic matter accumulation abstract lacustrine organic rich shales are widespread in the upper triassic yanchang formation chang 7 member of the ordos basin however information on the short term climate evolution within the chang 7 member is still lacking and the mechanism of organic accumulation in the shales remains controversial to address these issues this study analyzes the palaeoenvironment and depositional setting of different intervals in the chang 7 member of the southwestern ordos basin and constrains the main control factors on accumulation and preservation of organic matter based on organic major and trace element data the lower chang 73 shale which contains a high abundance of thermally mature type i and ii kerogen has excellent original hydrocarbon generative potential the lower chang 73 interval has the most humid climatic condition the strongest weathering condition a euxinic bottom water condition a high paleo productivity and a low terrigenous input during the period of upper chang 73 and chang 72 the climate became somewhat drier and hotter which was marked by relatively weak weathering conditions suboxic to anoxic conditions low paleoproductivity and high terrigenous input the chang 71 was characterized by a moderately humid climate moderate weathering conditions paleoproductivity and terrigenous input the relationship among the primary productivity redox conditions clastic influx indicators and toc content suggests that primary productivity was the most critical factor controlling the enrichment of organic matter the high primary productivity during the early chang 73 interval was probably driven by the deposition of volcanic ash and was influenced by marine incursion events a warm and humid paleoclimate combined with input of volcanic ash and seawater resulted in eutrophic nutrient rich and stratified surface water during the early chang 73 period which led to algal blooms with high primary productivity a stratified water column with high primary productivity together with oxygen deficit bottom water conditions and low terrigenous input resulted in the greatest enrichment of organic matter in the lower part of chang 73 shale

hydrocarbon potential of pennsylvanian coal in bohai gulf basin eastern china as revealed by hydrous pyrolysis abstract a hydrous pyrolysis experiment was performed using pennsylvanian brown coal with a vitrinite reflectance vr 0 of 0 56 from a coal mine at the southwest corner of the bohai gulf basin eastern china to evaluate the hydrocarbon potential of the coal the coal sample is vitrinite rich 74 5 and inertinite poor 16 7 with liptinite content of 8 8 much of the vitrinite in the sample consists of hydrogen rich vitrinite collodetrinite hydrous pyrolysis was performed at 200 c 230 c 260 c 290 c 320 c and 350 c for 72 h separately yields of both total liquid pyrolysates and expelled oil increased with temperature before reaching their maximum production of 17 27 kg t coal and 14 57 kg t coal at the same temperature of 320 c vr 0 1 18 and decreased afterwards gaseous products increased sharply at 320 c and tended to increase even at the highest experimental temperature 350 c vr 0 1 53 results show that the coal has not only a certain oil generation potential but also a large capacity for gas production and a high expulsion efficiency oil potential of the coal is attributed to its depositional environment which was transitional from shallow marine to coastal plain or swamp during middle to late pennsylvanian the coal was protected from oxidation under water after deposition experimental results indicate that this pennsylvanian coal could have contributed to oil gas accumulation in the bohai gulf basin

rank and petrographic composition of selected upper cretaceous and tertiary coals of southern nigeria abstract the rank and composition of upper cretaceous tertiary coals from five localities enugu orukpa okaba ihioma and azagba ogwashi in southern nigeria are described ranks determined by huminite reflectance measurements indicate a range from sub bituminous c to sub bituminous a coalification grade for the lower maastrichtian coals of the mamu formation whereas the oligocene miocene coals in the ogwashi asaba formation are predominantly of lignite rank the highest grade of sub bituminous a was attained in the enugu area onyeama mine in the south and this decreases towards the okaba mine where ranks are within the sub bituminous c coalification grade composition was determined by maceral analyses results indicate that the lower maastrichtian sub bituminous coals are characterized by moderate to high concentrations of huminites humodetrinites humocollinite and humotellinite and varied concentrations of inertinites and liptinites concentration of large amounts of liptinites especially resinite sporinite and cutinite at the bottom of the orukpa seam indicate the wet conditions of a reed swamp depositional environment whereas the large abundance of inertinites mainly fusinite on the top parts of the onyeama and okaba seams is interpreted as a shift to drier conditions possibly forest swamp facies the occurrence and predominance of humodetrinite attrinite and densinite in the tertiary lignites of ihioma and azagba ogwashi are interpreted as indications of reed swamp depositional environments we conclude that peat depositional environments for the lower maastrichtian coals was dominated by alternating high and low groundwater tables which resulted from recurrent subsidence forest and reed marsh swamps appear to have developed in delta plain environments lignites in the oligocene miocene stages accumulated in reed swamps of a less telmatic depositional environment

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

oil generating potential of tertiary coals and other organic rich sediments of the nyalau formation onshore sarawak the oil generating potential of coals and other organic rich sediments from the late oligocene early miocene nyalau formation the offshore extension of which is believed to be a major source rock is evaluated coals of the nyalau formation are typically dominated by vitrinite with moderate and low amounts of exinite and inertinite respectively significant amounts of clay minerals are present in these coals and those containing between 15 to 65 mineral matter by volume are termed carbargilite the samples analysed range from sub bituminous to high volatile bituminous rank possessing vitrinite reflectance in the range 0 42 to 0 72 tmax values range from 425 450 c which is in good agreement with vitrinite reflectance data good oil generating potential is anticipated from these coals and carbargilites with moderate to rich exinite content 15 35 this is supported by their high hydrogen indices of up to 400 mghc gtoc py gc s2 pyrograms with n alkane alkene doublets extending beyond nc30 and their being in the early to mid mature oil window range petrographically the most significant evidence of the oil generating potential of these coals is the generation of petroleum like materials exsudatinite visible under the microscope exsudatinite is a secondary maceral commonly considered to represent the very beginning of oil generation in coal which is shown here to also have an important role to play in hydrocarbon expulsion the precursor of exsudatinite in these coals is the maceral bituminite which readily expels or mobilizes to hydrocarbon like material in the form of oil smears and or exsudatinite as observed under the microscope the maceral bituminite is considered to play a major generative role via early exsudatinite generation which is considered to facilitate the overall expulsion process in coaly source rocks

guidelines for evaluating petroleum source rock using programmed pyrolysis rock eval pyrolysis is used to rapidly evaluate the petroleum generative potential and thermal maturity of rocks accurate conclusions require programs every 30 60 ft 9 18 m understanding of interpretive pitfalls and supporting data such as visual kerogen vitrinite reflectance and elemental analyses the generative potential of coals is commonly overestimated by pyrolysis and is best determined by elemental analysis and organic petrography most coals show high s2 s3 5 and low hi values 300 mg hc g toc migrated oil and mud additives which alter rock eval data can sometimes be removed by special processing for immature rocks bimodal s2 peaks and pi values over 0 2 indicate contamination pyrolysis downgrades organic poor clay rich rocks which show lower hi and higher tmax values than isolated kerogen because of adsorption of pyrolyzate on the clays tmax values for small s2 peaks 0 2 mg hc g toc are unreliable tmax is affected by maturation organic matter type contamination and the mineral matrix s3 is sensitive to inorganic and adsorbed carbon dioxide and to instrumentation problems acidification of carbonate rich samples and proper maintenance improves s3 measurement constant sample weights 100 mg are recommended below a threshold weight tmax increases by up to 10 c and other parameters decrease organic rich samples which overload the detector can be diluted with carbonate detector linearity is determined by pyrolyzing various weights of an organic rich rock

permian deposits and the permian triassic boundary in croatia palaeoclimatic implications based on palaeontological and geochemical data

illawarra reversal the fingerprint of a superplume that triggered pangean breakup and the end guadalupian permian mass extinction abstract the permian magnetostratigraphic record demonstrates that a remarkable change in geomagnetism occurred in the late guadalupian middle permian ca 265 ma from the long term stable kiaman reverse superchron throughout the late carboniferous and early middle permian to the permian triassic mixed superchron with frequent polarity changes in the late permian and triassic this unique episode called the illawarra reversal probably reflects a significant change in the geodynamo in the outer core of the planet after a 50 million years of stable geomagnetism the illawarra reversal was likely led by the appearance of a thermal instability at the 2900 km deep core mantle boundary in connection with mantle superplume activity the illawarra reversal and the guadalupian lopingian boundary event record the significant transition processes from the paleozoic to mesozoic modern world one of the major global environmental changes in the phanerozoic occurred almost simultaneously in the latest guadalupian as recorded in 1 mass extinction 2 ocean redox change 3 sharp isotopic excursions c and sr 4 sea level drop and 5 plume related volcanism in addition to the claimed possible links between the above listed environmental changes and mantle superplume activity i propose here an extra explanation that a change in the core s geodynamo may have played an important role in determining the course of the earth s surface climate and biotic extinction evolution when a superplume is launched from the core mantle boundary the resultant thermal instability makes the geodynamo s dipole of the outer core unstable and lowers the geomagnetic intensity being modulated by the geo and heliomagnetism the galactic cosmic ray flux into the earth s atmosphere changes with time the more cosmic rays penetrate through the atmosphere the more clouds develop to increase the albedo thus enhancing cooling of the earth s surface the illawarra reversal the kamura cooling event and other unique geologic phenomena in the late guadalupian are all concordantly explained as consequences of the superplume activity that initially triggered the breakup of pangea the secular change in cosmic radiation may explain not only the extinction related global climatic changes in the end guadalupian but also the long term global warming cooling trend in earth s history in terms of cloud coverage over the planet

paleoenvironmental reconstruction and hydrocarbon potentials of upper cretaceous sediments in the anambra basin southeastern nigeria abstract palynological organic petrographic and organic geochemical analyses of the campanian maastrichtian sediments in akukwa 2 well were carried out to infer their paleoenvironments origin of the organic matter and hydrocarbon generation potentials the toc values of the analysed sediments range from 0 27 3 02 wt while the s2 pyrolysis yield range from 0 55 to 3 35 mg hc g rock this indicates that the nkporo and mamu sediments possess fair source generative potential the samples contain type iii ii and type iii kerogen as shown by the present day hi values between 58 and 292 mg hc g toc and pyrolysis gc data the organic matter within the sediments is also likely to generate mainly gas this is in agreement with the petrographic observations which revealed that the analysed shale samples contain abundant vitrinite macerals apart from bituminite alginite cutinite and resinite also the sediments are immature to early mature in terms of hydrocarbon generation as indicated by vitrinite reflectance biomarker maturity and pyrolysis tmax data biomarker distribution ratios palynomorphs assemblage and organic petrographic observations further point out that the organic materials within the sediments were of mixed aquatic and terrigenous origin and were deposited under suboxic paleodepositional conditions based on sedimentological palynological and biomarker characteristics the environment of deposition of the analysed sediments was inferred to be a relatively quiet shallow marine with fluvial incursion most especially at the upper part of the intervals studied and consequently it is a delta associated depositional environment with a fluviatile influence the sediments are therefore suggested to be deposited in a paleogeographic setting close to vegetation source

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

the middle permian capitanian mass extinction on land and in the oceans abstract a middle permian mass extinction first discovered in 1994 has become known as the end guadalupian event in the literature however recent studies of foraminifera and brachiopod range truncations in conodont dated sections on the south china block have shown that the losses occur below this level in the middle of the capitanian stage extinctions were suffered by several other groups notably the corals whilst the mollusc record is more enigmatic a major bivalve crisis has been reported in some studies the giant alatoconchids being notable victims but not others gastropods were unaffected by the crisis whilst a roughly contemporaneous ammonoid mass extinction may have occurred in the early wuchiapingian a few million years after the main marine losses compilation of data from plant species in south china reveals a significant 24 loss suggesting that the capitanian crisis also occurred on land an intra capitanian extinction of 56 of plant species in north china block sequences may also have coincided with these losses correlation of these marine and terrestrial extinction events using the palaeomagnetic record provides two alternatives either turnover amongst plant species is contemporaneous with the marine extinction and the eruption of the emeishan flood basalt province in southwest china or plant losses post date the marine extinction and instead coincide with the waning phase of the igneous province current understanding of the major dinocephalian extinction suggests this event occurred during the preceding stage the wordian but future improvements in both sampling and dating this tetrapod crisis may reveal a synchronicity of plant animal and marine invertebrate extinctions the clear temporal link of the capitanian marine extinction with emeishan volcanism suggests that these flood basalt eruptions triggered the crisis a contemporaneous major negative c isotope excursion suggests that like many other mass extinction events methane release from hydrates may also be implicated however in the best dated chinese sections the main excursion is found to slightly post date the extinction which occurs at the end of an unusual and unexplained interval of exceptionally heavy 13c values other usual suspects for mass extinctions either lack geological and palaeontological evidence e g marine anoxia and global cooling or do not precisely correlate with the extinction e g major eustatic regression

mineralogy and geochemistry of palaeozoic black shales from peninsular malaysia implications for their origin and maturation abstract palaeozoic black shale bearing formations comprise 25 of the sedimentary cover in peninsular malaysia however nothing has been published regarding their geology composition and maturation representative samples from different ages and localities of the black shales were subjected to detailed mineralogical and geochemical investigations during this study to determine their origin these investigations also provide an opportunity to trace the changes in depositional environments and paleoclimate during the palaeozoic as well as the nature of unknown and hidden basement rocks in malaysia this paper reports nineteen palaeozoic formations in malaysia that contain black shales that are classified into seven categories based on their age these are the cambrian ordovician ordovician devonian silurian devonian devonian carboniferous carboniferous permian and permian black shales although illite was identified in all black shales other clay minerals including kaolinite and smectite illite mixed layers show significant variations among the studied samples the al 2 o 3 tio 2 ratios 13 33 sio 2 contents of probable magmatic source rocks 54 69 wt and zr tio 2 bivariate diagram suggest a mixture of felsic and intermediate source rocks for the studied black shales this indicates that the hidden basement rocks in malaysia are dominated by felsic igneous rocks variations in clay minerals sio 2 and al 2 o 3 tio 2 ratios and upper continental crust ucc normalized ree patterns suggest a local provenance for each locality rather than regional and common source rocks for all black shales al 2 o 3 sio 2 ratios vary from one age to the other ranging between 0 09 and 0 37 this indicates changes in the degree of weathering of the sediment source rocks of these shales and suggests climate changes in the peninsular malaysia during the palaeozoic from relatively wet conditions during the cambrian to relatively dry conditions during the ordovician followed by relatively wet conditions extends from the silurian to the carboniferous which followed by relatively dry conditions during the formation of carboniferous permian black shales and finally to relatively wet conditions during the permian the v ni v v ni and v v cr ratios as well as the positive ce anomalies indicate that these black shales were deposited under reducing conditions the high v ni ratios 3 also suggest a purely marine source input for the organic matter devonian black shales show relatively high concentrations of redox sensitive elements which may suggest the possible existence of devonian anoxia as well as the devonian carboniferous d c boundary in malaysia based on the abundance of illite 85 and illite crystallinity ic values 27 46 2 the majority of the palaeozoic black shales in peninsular malaysia are probably anchimetamorphic and over matured

hydrocarbon distribution in coals and in dispersed organic matter of different maceral compositions and maturities more than 60 samples from 5 coal seams and adjacent siltstones and sandstones were selected from a well through westphalian b sediments from northern germany in order to study bitumen generation and migration the cores were drilled between 1200 und 1530 metres depth in this interval vitrinite reflectance rr is increasing from 0 70 to 0 92 results reveal high hydrocarbon generation potentials for all coal samples but not for adjacent clastic rocks although maceral compositions of both are quite similar yields and compositions of thermal extracts from the coals depend on maceral compositions and rank however the bulk of the already generated bitumen has not been removed during natural coalification and is not easily releasable by thermovaporisation a mass balance based on elemental composition of dull coals indicates that in the rather narrow rank interval 0 70 0 92 rr a total mass loss of 20 may have occurred by migration this is evidenced by a loss of about 20 of the original hydrogen the rest being stored in the coals

organic petrological and organic geochemical characterisation of the tertiary coal bearing sequence of batu arang selangor malaysia abstract the tertiary coal bearing sequence at batu arang in selangor peninsular malaysia consists of a sandstone coal oil shale facies assemblage a detailed organic petrological and organic geochemical study was carried out on several organic rich sediments from this sequence the oil shales are dominated by botryococcus derived telalginite and pediastrum derived lamalginite the coals hypautochthonous in origin are mainly duroclarite type although other minor microlithotypes also occur alginite is not observed in the coals but other liptinitic constituents are very common particularly thin walled cutinite and sporinite the oil shales and the coals are thermally immature this immaturity has a considerable influence on the biomarker distributions particularly so on the triterpanes which are dominated by c 31 22r and c 30 compounds interestingly for tertiary aged sediments of continental origin the diagnostic biomarker compounds such as 18 h oleanane and bicadinanes normally linked to the higher land plant group of angiosperms are not observed in the samples analysed tricyclic terpanes occur only in very low relative abundance or are virtually absent a clear distinction however in the biomarker distributions of the shales and the coals carbargilite can be made based upon the distribution of c 27 c 29 regular steranes the shales with a source input being predominantly planktonic algae are dominated by 5 h 14 h 17 h 20r cholestane while the coals carbargilites with a source input consisting mainly of higher plant material are dominated by 5 h 14 h 17 h 20r ethyl cholestane the depositional environment of the batu arang coal bearing sequence is interpreted as varying from an alluvial flood plain peat swamp to fluvio lacustrine depositional setting

lithotype maceral composition and variation as correlated with paleo wetland environments gates formation northeastern british columbia canada abstract lithotype samples collected from mid albian gates formation coal seams in northeastern british columbia were analysed in order to gain a better understanding of coal facies variation compositional boundaries between lithotypes are gradational from bright to dull coals there is a progressive decrease in vitrinite and increase in inertinite liptinite is negligible

stochastic determination of well capture zones a stochastic approach is adopted for characterizing the uncertainty in well capture zones in heterogeneous formations transmissivity is modeled as a random space function and a monte carlo approach is used to infer the probability distribution of the resulting stochastic capture zones through several numerical experiments the influence of the statistical parameters of transmissivity variation on the extent of uncertainty in the location of the capture zone is investigated two aquifer models are considered a fully confined aquifer and a leaky confined aquifer receiving recharge from above a connection is made with previous work on transport theory and the statistical parameters of the capture zone probability distribution are compared with those of a solute concentration plume

organic geochemical and petrographic characteristics of tertiary coals in the northwest sarawak malaysia implications for palaeoenvironmental conditions and hydrocarbon generation potential abstract tertiary coals from mukah and balingian coalfields in the northwest sarawak malaysia were investigated to evaluate their regional rank variation petroleum generative potential and to reconstruct the palaeoenvironment conditions during peat accumulation the tertiary coals are characterized by high total organic carbon contents toc and yield of bitumen extraction ranging from 31 3 to 55 9 wt and 25 724 9 92 143 7 ppm respectively meet the standard as a good source rock potential the mukah and balingian coals were generally plotted in an area of type iii kerogen and mixed type ii iii kerogens with hi values between 90 and 289 mg hc g toc whereby the coals were derived from plant materials of terrigenous origin this shows that the balingian coals are dominated by type iii terrigenous kerogen while mukah coals are dominated by type ii iii kerogens and are thus considered to be generate mainly gas prone and limited oil prone this is also supported by macerals composition and open system pyrolysis gas chromatography py gc the mukah and balingian coals are thermally immature in rang from lignite to sub bituminous c rank possessing huminite reflectance in the range of 0 26 0 39 this immaturity has a considerable influence on the proximate analysis particularly on relatively high moisture and volatile matter contents and relatively low fixed carbon content petrographically it was observed that the mukah and balingian coals are dominated by huminite with low to high amounts of liptinite and relatively low amounts of inertinite pointing to predominantly anaerobic deposition conditions in the paleomires with limited thermal and oxidative tissue destruction the palaeoenvironment conditions of the coals are generally interpreted as a lower deltaic plain wet peat swamp depositional setting which are generally characterised by low tpi and high gi values and are plotted on the marsh field of the diessel s diagram this is usually consistent with generate relatively high ash yield as is the case of the mukah and balingian coals

a type of continuous petroleum accumulation system in the shulu sag bohai bay basin eastern china abstract this study analyzed crude oils from the lower part of the third member of the eocene shahejie formation es 3 l and three prospective source rocks from the shulu sag bohai bay basin eastern china using a variety of organic geochemical methods biomarker characteristics were used to interpret source rock organic matter input and depositional environment and oil source rock correlation the biomarker data indicate that the crude oils originated from the es 3 l source rock which contains a mixture of plankton and land plant organic matters deposited in brackish fresh water under reducing conditions the oil in the es 3 l is self sourced instead of migrated from the overlying source rocks the petroleum generation potential of the es 3 l source rock was evaluated using organic geochemistry total organic carbon toc values for approximately 100 samples are between 1 02 and 4 92 wt and hydrogen indices range from 285 to 810 mg hydrocarbons g toc the es 3 l source rock contains mainly type ii and iii kerogen and most of the samples are thermally mature the data show that the es 3 l source rock has good potential for liquid hydrocarbon generation the es 3 l rock also acts as the oil reservoir having very low bulk porosity and permeability various types of storage space in the marlstone and carbonate rudstone in the es 3 l of the shulu sag include 1 fractures 2 intergranular pores 3 dissolution pores 4 organic matter pores 5 intragranular pores and 6 seams around gravels pore size ranges from nanometers to millimeters because the oil was generated and stored in es 3 l strata which lack any obvious trap and seal and have low permeability the unit represents a continuous petroleum accumulation

the triassic conodonts of the nw malayan kodiang limestone revisited taxonomy and paleogeographic significance abstract the revision of the middle and early late triassic conodonts in the nogami 1968 collection from the nw malaya kodiang limestone formation provides clues to the multi element reconstruction of triassic gondolellacea septi to octomembrate multi elements characterize the families gondolellidae and gladigondolellidae nov fam the distribution of cratognathodiform and ozarkodiniform p2 elements supports the hypothesis of sexual dimorphism in gladigondolella rather than that of two genera pseudofurnishius murcianus confers a southern tethyan low latitude character to the kodiang limestone a part of the cimmerian string of terranes that in triassic times formed a diagonal partition between the gradually closing paleo tethys and the accordingly widening neo tethys our findings suggest that such a realm stretched from the southern alps dinarids in the west to malaya shan thai terrane in the east only the eastern edge collided with eurasia in the late triassic forming the platform of sundaland consequently the paleo tethys closure remained limited to se asia while a substantial paleo tethys still existed in western direction ending up in the pindos and vardar oceans the jurassic neo tethys ocean extended south of the consolidated se asia block and cimmerian string of terranes

organic geochemistry and reservoir characterization of the organic matter rich calcilutite in the shulu sag bohai bay basin north china abstract although extensive studies have been conducted on unconventional mudstone shales reservoirs in recent years little work has been performed on unconventional tight organic matter rich fine grained carbonate reservoirs the shulu sag is located in the southwestern corner of the jizhong depression in the bohai bay basin and filled with 400 1000 m of eocene lacustrine organic matter rich carbonates the study of the organic matter rich calcilutite in the shulu sag will provide a good opportunity to improve our knowledge of unconventional tight oil in north china the dominant minerals of calcilutite rocks in the shulu sag are carbonates including calcite and dolomite with an average of 61 5 wt the carbonate particles are predominantly in the clay to silt size range three lithofacies were identified laminated calcilutite massive calcilutite and calcisiltite calcilutite the calcilutite rocks including all the three lithofacies in the third unit of the shahejie formation in the eocene es3 have total organic carbon toc values ranging from 0 12 to 7 97 wt with an average of 1 66 wt most of the analyzed samples have good very good or excellent hydrocarbon potential the organic matter in the shulu samples is predominantly of type i to type ii kerogen with minor amounts of type iii kerogen the temperature of maximum yield of pyrolysate tmax values range from 424 to 452 c with an average of 444 c indicating most of samples are thermally mature with respect to oil generation the calcilutite samples have the free hydrocarbons s1 values from 0 03 to 2 32 mg hc g rock with an average of 0 5 mg hc g rock the hydrocarbons cracked from kerogen s2 yield values in the range of 0 08 57 08 mg hc g rock with an average of 9 06 mg hc g rock and hydrogen index hi values in the range of 55 749 mg hc g toc with an average of 464 mg hc g toc the organic rich calcilutite of the shulu sag has very good source rock generative potential and have obtained thermal maturity levels equivalent to the oil window the pores in the shulu calcilutite are of various types and sizes and were divided into three types 1 pores within organic matter 2 interparticle pores between detrital or authigenic particles and 3 intraparticle pores within detrital grains or crystals fractures in the shulu calcilutite are parallel to bedding high angle and vertical having a significant effect on hydrocarbon migration and production the organic matter and dolomite contents are the main factors that control calcilutite reservoir quality in the shulu sag

depositional setting and paleoenvironment of an alatoconchid bearing middle permian carbonate ramp sequence in the indochina terrane abstract a middle permian carbonate sequence at khao somphot in the south of the khao khwang platform has been measured and analyzed this sequence is characterized by prolific fossil content and large bizarre alatoconchid bivalves nine major microfacies types are differentiated and consist of algal foram facies fusuline facies alatoconchid facies lime mudstone wackestone facies laminated bindstone facies fine grained cortoid grainstone facies coral biostrome facies crinoidal packstone facies and carbonate breccia conglomerate facies laminated bindstone lime mudstone with fenestral fabric and algal foram facies represent loferites deposited in a restricted intertidal zone of an inner ramp fusuline grainstone and cortoid grainstone facies indicate sand shoals of an inner ramp the fusuline wackestone packstone and alatoconchid facies were deposited in a subtidal below fair weather wave base environment in the mid ramp the crinoidal facies which overlies collapse breccia possibly accumulated during transgression in the deeper part of the mid ramp storm deposits are prevalent throughout as thin accumulates and as alatoconchid floatstone rudstone coquinite layers and are common in mid ramp setting the khao khwang platform probably evolved from a rimmed platform in the early permian to a ramp in the middle permian the general trend of 13c composition from both brachiopod shell and rock matrix from the lower part of the study section wordian is significantly high moreover the 13c signature from this interval is up to 8 vpdb which suggests high productivity on the tropical tethyan shelf of the indochina terrane an abrupt negative shift in 13c in the late wordian and late capitanian indicating significant changes in paleoenvironment productivity and the carbon cycle is probably contemporaneous with the kamura event recorded from sediments of the mid panthalassa ocean in japan and elsewhere related to global cooling and a sea level lowstand

the mid capitanian middle permian mass extinction and carbon isotope record of south china abstract conodont c isotope and fossil and facies data are presented for the capitanian middle permian mass extinction record seen in platform carbonates maokou and wuchiaping formations of south china where limestones interdigitate with the volcanic succession of the emeishan large igneous province the maokou formation provides an extinction record marked by the loss of keriothecal walled fusulinaceans and a turnover in calcareous algae in sections within the emeishan province this crisis occurs at the base of the oldest record of volcanism from the jinogondolella altudaensis conodont zone of mid capitanian age around the periphery of the emeishan province this extinction level lies within the upper part of the maokou formation at a level where platform carbonate deposition was frequently interrupted by thick volcanic ash depositional events the assemblages of the uppermost maokou formation are characterised by typical late permian taxa although these levels still lie within the middle permian guadalupian series disaster taxa such as earlandia and diplosphaerina are locally prolifically abundant in the aftermath of the mass extinction the crisis is particularly noteworthy amongst photosynthetic taxa such as calcareous algae and fusulinaceans that probably harboured photosymbionts therefore a kill mechanism involving cooling from explosive volcanism and potentially acid rain from sulphate aerosols appears appropriate a composite 13ccarb curve calibrated against a high resolution conodont biostratigraphy reveals a major intra capitanian negative excursion of 5 superimposed on typically heavy 4 5 middle permian values this curve can also be recognised in panthalassan seamount carbonates of japan although this requires reassignment of apparently upper permian limestones to the middle permian in both china and japan the capitanian mass extinction occurs during the early stage of this major intra capitanian negative excursion assuming typical platform carbonate accumulation rates the records of the maokou formation suggest 13ccarb values fell at 0 01 kyr suggesting a catastrophic origin such as gas hydrate destabilisation is unlikely although a volcanic source is possible

alatoconchids giant permian bivalves from south china abstract alatoconchidae a unique bivalve family from the permian are characterized by a giant body size up to 100 cm long and unusual shell form with wing like flanges and coarse prismatic outer layer of the shell wall palaeogeographically they are restricted to low latitude tethyan and panthalassan regions however the clams have not been previously been reported from south china even though this is one of the main eastern palaeotethyan terranes here we show that these giant clams were in fact widely distributed in south china but they have been previously misidentified as phylloid algae the present study verifies their occurrence in the region using reconstruction of shell forms from a series of transverse sections as well as their characteristic shell microstructure the alatoconchids occur commonly as coquina beds over thirty occurrences ranging from the early kungurian to probably the latest capitanian in time have been found based on detailed lithological and microfacies observation at more than ten fossil localities most alatoconchid bearing horizons abh are autochthonous deposits confined to medium to thick bedded limestones often wackestone of shallow water carbonate platforms two occurrences from an intra platform basin are allochthonous deposits shed from the nearby carbonate platform by gravity flows and featured by completely disintegrated fragments autochthonous and condensed accumulation of the fossil materials with great lateral persistence imply a gregarious habit of the clam although slightly reworking might be involved its absence from high energy conditions as well as the completeness of shell preservation suggests it was not a reef dweller to obtain gigantism in the tropical oligotrophic environment alatoconchids may have harboured photosymbionts like present day tridacnids facilitated by its transparent shell texture although this notion is challenged by asato et al 2017 their association with calcareous algae and corals in the abh indicates that the optimum belt of the clams is likely within the euphotic zone but below that of calcareous green algae judging from the lithological succession and skeletal grain association

end guadalupian extinction of the permian gigantic bivalve alatoconchidae end of gigantism in tropical seas by cooling abstract the unique permian bivalve family alatoconchidae has aberrant shell forms and extraordinary size up to 1 m representing the largest bivalve group in the paleozoic their occurrence is reported sporadically from lower middle permian shallow marine carbonates in 9 areas in the world tunisia croatia oman iran afghanistan thailand malaysia the philippines and japan that cover low latitudes of both the tethyan and panthalassan domains alatoconchids almost always occurred in close association with large tested fusulines verbeekinidae and or rugose corals waagenophyllidae of the typical tethyan assemblage suggesting their preferential adaptation to shallow warm water tropical environments this tropical trio alatoconchidae verbeekinidae and waagenophyllidae became extinct either during the late guadalupian or around the guadalupian lopingian boundary g lb their intimate association and occurrence range suggest that these 3 taxonomically distinct clades may have shared not only a common habit but also a common cause of extinction the shell structure of alatoconchids suggests their symbiosis with photosynthetic organisms algae cyanobacteria in order to maintain their large body size that required high energy consuming metabolism in contrast to smaller forms the alatoconchidae attained their largest size in the wordian middle guadalupian probably maximizing the benefits of photosymbiosis the subsequent extinction of the warm water adapted tropical trio both in tethys and panthalassa positively supports the explanation that a critical cooling took place on a global scale including low latitude oceans the end of the gigantism in fusulines and bivalves in the capitanian late guadalupian was likely caused by the collapse of photosymbiotic systems during a temporary temperature drop of seawater kamura cooling event coupled with eutrophication that was detrimental to the tropical fauna adapted particularly to oligotrophic conditions gigantism of bivalves occurred several times in the phanerozoic e g siluro devonian permian triassic early jurassic and jurassic creataceous mostly in warm periods the sea level change in the phanerozoic apparently synchronized with the intermittent rise and decline of bivalve gigantism suggesting that the photosymbiosis related gigantism in low latitudes may serve as a potential monitor of global warming cooling in the past

stochastic determination of three dimensional capture zones for a fully penetrating well 1 a stochastic methodology is used to investigate transport of a conservative solute by steady flow to a fully penetrating pumping well in a three dimensional heterogeneous formation the spatially variable hydraulic conductivity is modeled as a stationary random function of anisotropic two point covariance although mean transport is radial heterogeneity produces three dimensional velocity fluctuations which are shown to affect solute recovery and the capture zone distribution expressions accurate to the first order in log conductivity variance y2 are derived for travel time variance capture zone extent and solute recovery under the following simplifying assumptions 1 the vertical integral scale of conductivity is much less than the horizontal integral scale 2 the depth of the formation is much greater than the vertical integral scale of conductivity 3 the well bore diameter is much smaller than the horizontal scale of conductivity 4 longitudinal and lateral local dispersion are negligible while the effect of transverse dispersion is examined travel time variance 2 for transport in convergent flow in a three dimensional aquifer is shown to be greater than 2 in either constant mean flow in a three dimensional formation or radially convergent flow in a heterogeneous two dimensional medium transverse dispersion between layers in a sedimentary formation is found to increase mixing between flow paths leading to a marginal reduction in travel time variance because of negative correlation between mass flux and travel time solute retrieval at the well occurs earlier from a constant flux solute source than from an instantaneous plume the relationship between initial plume length and relative plume spreading is illustrated for simple plume geometries

modeling of gas generation from the alam el bueib formation in the shoushan basin northern western desert of egypt the shoushan basin is an important hydrocarbon province in the northern western desert egypt but the burial thermal histories for most of the source rocks in the basin have not been assigned yet in this study subsurface samples from selected wells were collected to characterize the source rocks of alam el bueib formation and to study thermal history in the shoushan basin the lower cretaceous alam el bueib formation is widespread in the shoushan basin which is composed mainly of shales and sandstones with minor carbonate rocks deposited in a marine environment the gas generative potential of the lower cretaceous alam el bueib formation in the shoushan basin was evaluated by rock eval pyrolysis most samples contain sufficient type iii organic matter to be considered gas prone vitrinite reflectance was measured at eight stratigraphic levels jurassic cretaceous vitrinite reflectance profiles show a general increase of vitrinite reflectance with depth vitrinite reflectance values of alam el bueib formation range between 0 70 and 0 87 vrr indicating a thermal maturity level sufficient for hydrocarbon generation thermal maturity and burial histories models predict that the alam el bueib source rock entered the mid mature stage for hydrocarbon generation in the tertiary these models indicate that the onset of gas generation from the alam el bueib source rock began in the paleocene 60 ma and the maximum volume of gas generation occurred during the pliocene 3 2 ma

petrology palynology coal facies and depositional environments of an upper carboniferous coal seam minto coalfield new brunswick canada coal petrology and palynology of the minto coal seam enable depositional environments of the precursor mire to be established in terms of facies critical maceral ratios maceral assemblages and spore and pollen assemblages the overall petrographic composition indicates a vitrinite rich coal mean 67 followed by inertinite mean 27 and liptinite mean 7 pyrite is common to abundant maximum 15 lithotype logs demonstrate a dominance of dull lithotypes dull and banded dull petrographic composition at the lithotype and seam subsection level is highly variable vitrinite maceral assemblages are enriched in brighter lithotypes banded bright and bright whereas liptinite and inertinite maceral assemblages are enriched in dull and banded dull lithotypes the duller lithotypes are enriched by mineral matter based on spores the seam is assigned to the vestispora zone of atlantic canada with the basal torispora securis torispora laevigata sl zone of western europe and the lower torispora secur

the atlas east variscan elbe shear system and its role in the formation of the pull apart late palaeozoic basins the variscan orogeny occurred as a result of the late devonian to late carboniferous collision and accretion of gondwana derived microcontinents and continental masses with those of laurussia the irregular boundaries of the colliding continents caused isochronous transpressional and transtensional tectonics accompanied by a complex pattern of intracontinental shear zones at the scale of the southern european variscides these shear zones and their configuration controlled the subsequent evolution of permian to middle triassic paleogeography the geographic distribution from morocco to the eastern alps of the late carboniferous permian up to triassic basins most of which are considered as pull apart basins was related with the development of the late palaeozoic intracontinental shear network our analysis of the stratigraphic tectonic and volcanic features of the late carboniferous permian continental basins across the laurussia gondwana boundary reveals the role of the east variscan shear zone during this time as a precursory lineament for the development of the permian to triassic rifting of pangaea and the following opening of oceanic basins e g the neothetyan ocean

pristane phytane ratios in the mineralized kupferschiefer of the fore sudetic monocline southwest poland abstract the interaction of organic matter with fluids is important in geochemical processes in surface and diagenetic environments in the kupferschiefer copper deposits of southwestern poland organic fluid interactions are inferred to have been important in the genesis of the ore deposits previous organic geochemical studies of the kupferschiefer report evidence of a late diagenetic oxidation event that altered the organic geochemistry this study uses the saturated hydrocarbons as indicators of the biological input and the earliest diagenetic processes to affect the organic geochemistry of the kupferschiefer the normal alkane distributions are lithofacies controlled indicating that they reflect biological input the ratio of the saturated isoprenoids pristane phytane are potential indicators of the redox conditions during sedimentation and diagenesis very low pr ph ratios are associated with lithofacies that were deposited in hypersaline environments increases in the pr ph ratio within individual traverses are interpreted as indicating increasing oxidation of organic matter during deposition and early diagenesis trends of increasing pristane phytane ratios are observed at the base of the kupferschiefer and at the transition within the kupferschiefer from the clay rich to the carbonate rich kupferschiefer which corresponds approximately to the transition from cu zone to the pb zone early diagenetic copper depleted cu and cu fe sulfides have also been reported form the top of the weissliegendes and the cu zone pb zone transition and it is conceivable that both could be related to the same processes

correlation of different maturity parameters in the ahmedabad mehsana block of the cambay basin abstract the potential use of organic matter maturation parameters in assessing the diagenetic catagenetic transition zone with the help of various known molecular parameters has been investigated in the ahmedabad mehsana block of the cambay basin a set of 24 conventional cores from the eocene shales covering a depth regime of 922 2500 m has been studied the oil generation threshold i e the boundary between the diagenetic and catagenetic maturation regimes is assessed to be at 1800 m based on a combination of parameters including percent hydrocarbons in eom saturate aromatic hydrocarbon ratio in eom and the rock eval production index the pr n c17 ratio rock eval hi and oi were not suitable for reliable maturation profiling nor for independently indexing the stages of maturation the extent of the catagenetic regime is distinguished by ph n c18 ratios

sensitivity of biomarker properties to depositional environment and or source input in the lower toarcian of sw germany abstract a sequence of lower toarcian sediments which are highly contrasting in their depositional environment over a 5 m depth interval has been investigated in detail for the variability of geochemical properties which are used for source characterization and oil to source correlation lower liassic marls are representative of a well aerated shallow water environment in contrast to the immediately overlying bituminous shales which are deposited under extremely reducing conditions various properties have been found to vary considerably within these two units amongst the most important are carbon isotopic composition of the kerogen the pristane phytane ratios nickel as opposed to vanadyl porphyrins and the c27 dia regular steranes although maturation within the profile does not change some of the maturation dependent biomarker properties such as the monoaromatic steroid side chain cracking and the tm ts ratio exhibit large changes which can be assigned to diagenetic processes another maturation dependent property the 20s 20r epimerization of c29 steranes exhibits smaller changes which could also be due to early diagenetic processes the study suggests that reducing and oxidizing conditions i e eh and ph in the sediment exert an influence on several biomarker precursor product pathways in maturation studies initial variations due to depositional conditions have therefore to be taken into account

growth and demise of permian biogenic chert along northwest pangea evidence for end permian collapse of thermohaline circulation abstract the permian chert event pce was a 30 ma long episode of unusual chert accumulation along the northwest margin of pangea and possibly worldwide the onset of the pce occurred at about the sakmarian artinskian boundary in the sverdrup basin canadian arctic where it coincides with a maximum flooding event the ending of high frequency high amplitude shelf cyclicity the onset of massive biogenic chert deposition in deep water distal areas and a long term shift from warm to cool water carbonate sedimentation in shallow water proximal areas a similar and coeval shift is observed from the barents sea to the northwestern usa a landward and southward expansion of silica factories occurred during the middle and late permian at which time warm water carbonate producers disappeared completely from the northwest margin of pangea biotically impoverished and increasingly narrow cold water carbonate factories characterised by non cemented bioclasts of sponges bryozoans echinoderms and brachiopods were then progressively replaced by silica factories by late permian time little carbonate sediments accumulated in the barents sea and in the sverdrup basin where the deep to shallow water sedimentary spectrum was occupied by siliceous sponge spicules by that time biogenic silica sedimentation was common throughout the world silica factories collapsed in the late permian abruptly bringing the pce to an end in northwest pangea the end permian collapse of the pce was associated with a major transgression and with a return to much warmer oceanic and continental climatic conditions chert deposition resumed in the distal oceanic areas during the early middle triassic anisian after a 8 10 ma interruption early triassic chert gap the conditions necessary for the onset expansion and zenith of the pce were provided by the thermohaline circulation of nutrient rich cold waters along the northwestern and western margin of pangea and possibly throughout the world oceans these conditions provided an efficient transportation mechanism that constantly replenished the supply of silica in the area created a nutrient and oxygen rich environment favouring siliceous biogenic productivity established cold sea floor conditions hindering silica dissolution while increasing calcium carbonate solubility and provided conditions adverse to organic and inorganic carbonate production the northwest margin of pangea was for nearly 30 ma bathed by cold waters presumably derived from the seasonal melting of northern sea ice the assumed engine for thermohaline circulation this process started near the sakmarian artinskian boundary intensified throughout middle and late permian time and ceased suddenly in latest permian time it led to oceanic conditions much colder than normally expected from the palaeolatitudes and the influence of cold northerly derived water was felt as far south southern nevada the demise of silica factories was caused by the rapid breakdown of these conditions and the establishment of a much warmer marine environment accompanied by sluggish circulation and perhaps a reduced input of dissolved silica to the ocean complete thawing of northern sea ice would have ended thermohaline circulation and led to warm and sluggish oceanic conditions inimical to the production accumulation and preservation of biogenic silica

palaeomagnetism and rock magnetism of the permian redbeds from the velebit mt karst dinarides croatia dating of the early alpine tectonics in the western dinarides by a secondary magnetization abstract the studied area of the velebit mt a part of the adria microplate belonged to a ne margin of gondwana during the carboniferous and permian while the carboniferous to the early permian was characterised by deposition of clastic rocks younger sedimentation was dominated by a thick sequence of carbonate rocks the lower permian deposits of the core part of the velebit mt at kosna and crne grede localities were investigated using palaeomagnetic and rock magnetic measurements the main remanence carriers were recognized as haematite with an increasing contribution of sp sd magnetite in younger subsections the ams fabric with low anisotropy ratio 1 3 is strongly oblate at kosna and weakly prolate at crne grede reflecting differences in the contribution of magnetic phases a significant remagnetization of the permian rocks as proved by results of a conglomerate test probably caused by a combination of elevated temperatures and fluid migration may be assigned to burial related processes that affected the rocks before the final uplift of the dinarides characteristic remanent magnetizations recorded in haematite are apparently similar to the permian direction for africa shallow inclination with nnw declination as expected for velebit mt coordinates paradoxically this orientation is observed in situ within the almost vertically dipping beds we explain this relationship assuming a syn folding cretaceous remagnetization of the rocks at their subhorizontal position ca 30 s in which a mean vector of the secondary remanence overlaps with the cretaceous direction expected for africa at the velebit mt geographical coordinates consequently our results indirectly point to the cretaceous time of incipient stages of the dinaric tectonism and suggest african geotectonic affinity of the velebit rocks no important vertical axis rotation is implied by our results in contrast to previously published data the puzzling complete remagnetization carried by haematite at relatively low to moderate temperatures is also discussed

oleananes in oils and sediments evidence of marine influence during early diagenesis abstract the oleananes as markers for the angiosperms provide valuable source and age information when present in an oil nevertheless they are not quantitatively related to the land plant input and indeed their presence reflects only a small leak in diagenetic processes leading primarily to aromatic oleanoids because they are minor products the abundance of oleananes in terrigenous oils and sediments may be highly sensitive to changes in early diagenetic conditions here we present evidence that contact of plant matter with seawater during early diagenesis enhances the expression of oleananes in a mature sediment or oil oleananes are absent or present at very low concentrations in samples from the base of an eocene coal seam affected by postdepositional seawater intrusion however their abundance increases toward the top of the seam in correlation with organic sulphur dibenzothiophene phenanthrene and the homohopane index similarly in deltaic sediments from the south sumatra basin oleanane hopane is strongly correlated with indicators of marine influence such as c 27 c 29 steranes and the homohopane index in each case increasing oleanane abundance is accompanied by a reduction in the extent of aromatisation and for the south sumatra basin the proportion of a ring contracted oleananes an angiosperm derived miocene coal from the philippines deposited under freshwater conditions shows abundant aromatic oleanoids but no oleananes these results show that oleananes need to be used with caution as age and source markers in fluvio deltaic and lacustrine petroleum systems on the other hand their sensitivity to early diagenetic conditions may make them useful in locating effective source rocks in such systems

evolution of the adriatic carbonate platform palaeogeography main events and depositional dynamics abstract the adriatic carbonate platform adcp is one of the largest mesozoic carbonate platforms of the perimediterranean region its deposits comprise a major part of the entire carbonate succession of the croatian karst external or outer dinarides which is very thick in places more than 8000 m and ranges in age from the middle permian or even upper carboniferous to the eocene however only deposits ranging from the top of the lower jurassic toarcian to the top of the cretaceous can be attributed to the adcp defined as an isolated palaeogeographical entity although the entire carbonate succession of the karst dinarides was deposited within carbonate platform environments there were different types of carbonate platforms located in different palaeogeographical settings carboniferous to middle triassic mixed siliciclastic carbonate deposits were accumulated along the gondwanian margin on a spacious epeiric carbonate platform after tectonic activity culminating by regional middle triassic volcanism recorded throughout adria the african promontory a huge isolated carbonate southern tethyan megaplatform abbreviated as stm was formed with the area of the future adcp located in its inner part tectonic disintegration of the megaplatform during the middle to late early jurassic resulted in the establishment of several carbonate platforms including the adriatic apenninic and apulian separated by newly drowned deeper marine areas including the adriatic basin as a connection between the ionian and belluno basins lagonero basin and the area of the slovenian and bosnian troughs the adcp was characterised by predominantly shallow marine deposition although short or long periods of emergence were numerous as a consequence of the interaction of synsedimentary tectonics and eustatic changes also several events of temporary platform drowning were recorded especially in the late cretaceous when synsedimentary tectonics became stronger leading up to the final disintegration of the adcp the thickness of deposits formed during the 125 my of the adcp s existence is variable between 3500 and 5000 m the end of adcp deposition was marked by regional emergence between the cretaceous and the palaeogene deposition during the palaeogene was mainly controlled by intense synsedimentary tectonic deformation of the former platform area some carbonates mostly eocene in age were deposited on irregular ramp type carbonate platforms surrounding newly formed flysch basins and the final uplift of the dinarides reached its maximum in the oligocene miocene the adriatic carbonate platform represents a part although a relatively large and well preserved one of the broader shallow water carbonate platform that extended from ne italy to turkey although its continuity is somewhat debatable in the area near albanian greece boundary this large carbonate body which was deformed mostly in the cenozoic including a significant reduction of its width needs a specific name and the central mediterranean carbonate platform is proposed abbreviated to cmcp although the local names such as adcp for its nw part should be kept to enable easier communication and to facilitate description of local differences in platform evolution

microfacies and depositional environment of tertiary tanjung enim low rank coal south sumatra basin indonesia abstract the south sumatra basin is among the most important coal producing basins in indonesia results of an organic petrography study on coals from tanjung enim south sumatra basin are reported the studied low rank coals have a mean random huminite reflectance between 0 35 and 0 46 and are dominated by huminite 34 6 94 6 vol less abundant are liptinite 4 0 61 4 vol and inertinite 0 2 43 9 vol minerals are found only in small amounts 0 2 vol mostly as iron sulfide based on maceral assemblages the coals can be grouped into five classes 1 humotelinite rich group 2 humodetrinite rich group 3 humocollinite rich group 4 inertinite rich group and 5 humodetrinite liptinite rich group comparing the distribution of maceral assemblages to the maceral or pre maceral assemblages in modern tropical domed peat in indonesia reveals many similarities the basal section of the studied coal seams is represented typically by the humodetrinite liptinite rich group this section might be derived from sapric or fine hemic peat often occurring at the base of modern peats the middle section of the seams is characterized by humotelinite rich and humocollinite rich groups the precursors of these groups were hemic and fine hemic peats the top section of the coal seams is typically represented by the humodetrinite rich or inertinite rich group these groups are the counterparts of fibric peat at the top of the modern peats the sequence of maceral assemblages thus represents the change of topogenous to ombrogenous peat and the development of a raised peat bog a comparison between the result of detailed maceral assemblage analysis and the paleodepositional environment as established from coal maceral ratio calculation indicates that the use of coal maceral ratio diagrams developed for other coal deposits fails to deduce paleo peat development for these young tropical coals in particular mineral distribution and composition should not be neglected in coal facies interpretations

uncertainty estimation of well catchments in heterogeneous aquifers 1 the uncertainty in the boundary of two dimensional steady state well catchments due to the uncertainty of the spatially variable hydraulic conductivity field is investigated the well discharge rate and the areal recharge rate are assumed constant the catchment boundary is traced by backward particle tracking in the velocity field the uncertainty bandwidth of the catchment boundary is approximated in first order by formulating the time dependent longitudinal and transversal second moments of the particle displacements along and normal to the mean particle trajectory applications of the approach are presented for a set of simple configurations the results are compared with the results from unconditional numerical monte carlo simulations the comparison allows an assessment of the accuracy the applicability and the limits of the method the approximation corresponds quite well with the monte carlo simulations provided that the distance to the domain boundary is sufficiently large

constraining paleo latitude of a biogeographic boundary in mid panthalassa fusuline province shift on the late guadalupian permian migrating seamount abstract the guadalupian paleo atoll limestone iwato formation in sw japan was primarily formed in low latitude mid panthalassa and was later tectonically accreted to south china japan margin during the jurassic the present biostratigraphic study clarified that the iwato formation consists of 5 biostratigraphical intervals i e four fusuline assemblage zones assemblage zones 1 to 4 and a barren interval on the top assemblage zones 1 to 4 correspond to the neoschwagerina craticulifera zone n margaritae zone yabeina globosa zone and lepidolina multiseptata zone of the conventional tethyan fusuline stratigraphy respectively the present study newly clarified the following significant aspects of paleobiogeography of the permian fusulines as to the extinction of large tested taxa in the latest guadalupian 1 the long unknown stratigraphic relationship was documented for the first time between the yabeina dominant interval and the overlying lepidolina dominant one within a single limestone unit 2 the occurrence of lepidolina cf kumaensis kanmera the unique last runner of large tested fusuine was detected for the first time in mid oceanic paleo atoll limestones 3 with respect to the northbound migration history of the paleo seamount capped by the iwato formation the development of the two coeval fusuline biogeographic territories in the low latitude panthalassa i e the yabeina territory on the south and the lepidolina territory on the north was confirmed 4 the paleo latitude of the biogeographic boundary between the yabeina and lepidolina territories is constrained around 12 in the southern hemisphere on the basis of the latest geomagnetic data from the same limestone this new approach utilizing biostratigraphy on ancient migrating seamounts coupled with geomagnetic paleo latitude data is applicable to other cases in different time space co ordinates and of other fossil groups for constraining position of ancient biogeographic boundaries within lost oceanic domains of deep past

fusuline biotic turnover across the guadalupian lopingian middle upper permian boundary in mid oceanic carbonate buildups biostratigraphy of accreted limestone in japan abstract two sections in upper middle to lower upper permian shallow water limestones at kamura and akasaka in southwest japan were analyzed for detailed lithostratigraphy and biostratigraphy both sections represent ancient seamount capping carbonate buildups developed on a basaltic basement in a mid oceanic environment the occurrence of abundant tethyan fusulines allows the recognition of well defined biostratigraphic zonation in both sections and their mutual correlation the upper guadalupian middle permian lepidolina yabeina zone is overlain conformably by the lower lopingian upper permian codonofusiella reichelina zone with a 13 m thick transitional interval barren of index taxa the guadalupian lopingian g l boundary is marked by the first appearance datum fad of the lopingian codonofusiella reichelina assemblage in both sections this study recognizes for the first time the g l boundary horizon in a mid oceanic shallow water environment in addition the shallow water carbonates in the study sections record the extinction of the middle permian large sized fusuline family verbeekinidae at the g l boundary in mid panthalassa as well as in shallow water tethyan shelf areas demonstrating positively that the g l boundary mass extinction occurred on a global scale the abrupt elimination of large shelled fusulines followed by the domination of small shelled fusulines may indicate that environmental stress occurred at the end of guadalupian the dying out of symbiotic algae may have caused the selective extinction of the large shelled fusulines

hydrocarbon potential of middle and upper devonian coals from melville island arctic canada abstract some of the oldest coals in the world are found within the middle to upper devonian clastic wedge of the canadian arctic archipelago the coals investigated here occur in the weatherall hecla bay and beverly inlet formations on western melville island and range in age from late givetian to middle frasnian many of these coals are rich in liptinite macerals particularly sporinite and hence can be termed canned coals both elemental and rock eval analysis indicate these coals have the potential to generate liquid hydrocarbons a good correlation between liptinite with both h c or hydrogen index is observed up to about 50 liptinite after which the latter two parameters level off the coals range in maturity from 0 61 to 0 87 r o and hence should be in the oil window the amounts of hydrocarbons that can be extracted from the coals when expressed in mg g organic carbon are very low suggesting that they are poor source rocks for oil all the extracts except for the most mature and vitrinite rich sample show high pr ph ratios and biomodal n alkane distributions a cannel coal from the beverley inlet formation has a very unusual triterpane distribution that includes regular ab ring desmethyl and ab ring methyl hopanes steranes are in very low concentrations compared to hopanes in all samples the relative abundance of c 28 and c 29 steranes appears to be influenced by maceral composition hydrous pyrolysis at 330 c for 72 h generated greater amounts of hydrocarbons from the coals suggesting they could be the source of liquid hydrocarbons at greater maturities the hydrous pyrolysis experiments also indicate that thin walled spores are more reactive than thick walled spores at lower temperatures the coals on melville island are not thought to be significant source rocks for the oil and gas occurrences in this area of the canadian arctic because they make up only a very small fraction of the total sedimentary package

sedimentology organic geochemistry and petroleum potential of jurassic coal measures tarim junggar and turpan basins northwest china lower and middle jurassic coal bearing strata occur widely throughout central asia and are well developed in northwestern china where their thicknesses in the southern junggar northern tarim and turpan basins exceed 2500 2300 and 1500 m respectively examination of these strata along 13 transects across basin margin outcrop belts indicates that they are entirely nonmarine meandering fluvial deposits with local development of braided fluvial and lacustrine deltaic facies chinese subsurface data suggest that regional jurassic lacustrine facies are present down depositional dip consistent with predictions from global circulation modeling of early and middle jurassic monsoonal precipitation laboratory analyses of coals and organic rich shales show a dominance of terrestrial higher plant components visual kerogen analysis indicates that vitrinite inertinite and exinite are the dominant macerals and elemental analysis characterizes most kerogens as type iii rock eval analyses yield moderate hydrogen index values 50 300 and very low oxygen index values 20 jurassic source rock extracts are characterized by odd over even normal alkane distributions high pristane phytane and high hopane sterane ratios dominance of c29 sterane homologs local abundance of diterpenoid compounds and low abundance of tricyclic terpanes geochemical correlation with four petroleums from the junggar tarim and turpan basins strongly suggests that the jurassic coaly deposits and their lacustrine equivalents downdip are petroleum source rocks sterane and hopane distributions of petroleums and extracts of their putative jurassic source rock are similar and can be easily distinguished from published distributions of these compounds in other source rock layers additional correlation parameters include high pristane phytane low abundance or lack of tricyclic terpanes but similar distributions where present and lack of gammacerane with one exception and carotanes compounds that characterize permian and ordovician source rocks and their respective petroleums pyrolysis gas chromatography of selected jurassic samples s ggests that they possess potential for liquid hydrocarbon generation expulsion of c15 hydrocarbons from jurassic source rocks appears likely despite the traditional view that bituminous coals are incapable of expelling long chain hydrocarbons end page 929

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

organic petrographic characteristics of tertiary oligocene miocene coals from eastern malaysia rank and evidence for petroleum generation abstract oligocene to miocene coals from eastern malaysia were analysed to evaluate their regional ranks and petroleum generative potential the current study performs organic geochemical characteristics of the coals and identifies macerals based on their organic petrographic characteristics as observed under reflected white light and blue light excitations the coals are characterised by relatively high hydrogen index values between 282 and 516 mg hc g toc this indicates that these coals are dominated by type ii to mixed type ii iii kerogens and are thus considered to be generated mainly oil prone and limited gas prone this is supported by the presence of significant amounts 11 31 by volume of oil prone liptinite macerals suberinite is among the most common of the oil prone liptinite macerals in coals these coals likely are to be potential petroleum sources thus where the former is abundant waxy oils and naphthenic oil might be expected this has been supported by the distribution of n alkyl chains within kerogen pyrolysates predicting the generation of a mainly paraffinic and paraffinic naphthenic aromatic p n a high wax oils the coals are thermally early mature and coal rank in the region is subbituminous a to high volatile bituminous c possessing vitrinite reflectance in the range of 0 50 0 67 this maturity has a considerable influence on the proximate analysis particularly on a relatively low moisture content and relatively high fixed carbon and low volatile matter contents although these onshore coals are thermally early mature for petroleum generation the stratigraphic equivalent of these sediments offshore is known to have been buried to deeper depth and could therefore act as potential source rock for mainly oil with minor amounts of gas

climate driven paleolimnological change controls lacustrine mudstone depositional process and organic matter accumulation constraints from lithofacies and geochemical studies in the zhanhua depression eastern china abstract the influence of paleoclimate on the depositional process of lacustrine mudstone and organic matter accumulation is important to both paleoclimate reconstruction and hydrocarbon exploration here we study the lower third member es3l of the eocene shahejie formation in the zhanhua depression bohai bay basin eastern china in order to understand how paleoclimate influenced depositional processes and organic matter accumulation of lacustrine organic rich mudstone by combining detailed core descriptions and microscopic observations and high resolution mineralogical and geochemical analyses we identified two major lithofacies including massive calcareous mudstone and laminated calcareous mudstone from the luo 69 drilling core the sedimentologic observations and changes of geochemical proxies including detritus index ln al2o3 na2o b ga and v v ni suggest that the massive calcareous mudstone was deposited in a small shallow salt lake that was dysoxic anoxic and the paleoclimate in the lake catchment was cool and arid and the laminated calcareous mudstone was deposited in a large and deep stratified lake which has anoxic highly saline bottom and oxic less saline surface water and the lake catchment was more humid and warm the dominant lithofacies changed from laminated calcareous mudstone to massive calcareous mudstone in the studied core suggesting that the lake became shallower and smaller when the paleoclimate became cooler and drier through time such a climate trend may be a response to global cooling during the middle eocene the average total organic content toc in both lacustrine highstand and lowstand are comparable even though the lake water chemistry and amount of terrigenous input are different we infer that the accumulation of organic matter within the lacustrine highstand was controlled by the combination of primary productivity carbonate production and preservation in anoxic bottom water while accumulation within lacustrine lowstand was only controlled by primary productivity

equatorial palaeotethys as the last sanctuary for late permian metazoan reef builders new evidence from the bellerophon formation of slovenia the rise and demise of warm temperate permian reefs and biostromes reflect the complex geologic history of this dynamic period environments suitable for reef builders were devastated by the guadalupian lopingian crisis and lopingian reefs have only been recorded at a small number of localities the uppermost permian limestones of the bellerophon formation on the vojsko plateau slovenia contain small lenticular biostromes within a bioclastic wackestone packstone lithofacies the major biostrome builders are medium sized coralline sponges demospongea and calcarea encrusted by smaller sponges tube worms sessile foraminifera calcareous algae archaeolithoporella and shamovella i e tubiphytes all of which are typically covered by microbial crusts the biostromes are characteristically composed of bafflestone and bindstone incorporating sporadic framestone narrow belts of floatstone surround the buildups and sponge debris is also present in lenses within the mud matrix between metazoan bafflestones the fossils are generally well preserved although the fine skeletal microstructure has been partially recrystallized sponges are heavily calcified and ontogenic thickening of the skeleton can be observed in some encrusters framboidal pyrite forming thin films on the inner walls of sponge chambers suggests the presence of sulphate reducing bacteria these microbial symbionts may have enabled the sponges to survive in the anoxic marine environments of the uppermost permian the changshingian sponge biostromes of the vojsko plateau represent the westernmost known occurrence of contemporary metazoan boundstones in the palaeotethys

reply to the comment by j r ali on illawarra reversal the fingerprint of a superplume that triggered pangean breakup and the end guadalupian permian mass extinction by yukio isozaki abstract the following four major questions were raised about my recent proposal for the possible link between the end guadalupian extinction and a unique geomagnetic event called the illawarra reversal isozaki 2009a 1 timings of extinction cooling and the illawarra reversal end of the kiaman superchron 2 geomagnetic intensity during superchrons 3 ascent rate of mantle plume and 4 age constraints of lip volcanism in east pangea the latest research results on the permian biodiversity change numerical modeling of plume and single crystal measurement of geomagnetism support that the timings of extinction and the illawarra reversal high field intensity during the kiaman superchron and ascent rate of plume are reasonably explained in accordance with the integrated plume winter scenario isozaki 2009b the onset ages of lip volcanism need further refinement for identifying the impingement of a plume head

guadalupian middle permian ocean redox evolution in south china and its implications for mass extinction abstract the guadalupian mass extinction was a long term biocrisis that started in the early guadalupian epoch permian period many studies of the causes of the extinction have focused on the late guadalupian although the entire guadalupian should be studied to address its origins the selective nature of the species removed during the guadalupian extinction also remains a puzzle here we present pyrite framboid size distributions pyrite sulfur isotopic compositions and c n s profiles for the entire guadalupian from south china to develop a record of ocean redox evolution to help understand the selective extinction our results indicate that euxinia was mostly persistent in the deep water platform basin throughout the guadalupian which triggered long term early and middle guadalupian shallow water dysoxia and frequent episodic late guadalupian euxinia events that resulted in a gradual long term early and middle guadalupian diversity decrease and selective late guadalupian extinction the combined effect of euxinia and global regression led to selective extinction of taxa that had weakly buffered respiratory physiology and high growth efficiency such as brachiopods large fusulinids and giant bivalves

liquid hydrocarbon generation potential from tertiary nyalau formation coals in the onshore sarawak eastern malaysia tertiary coals exposed in the north central part of onshore sarawak are evaluated and their depositional environments are interpreted total organic carbon contents toc of the coals range from 58 1 to 80 9 wt and yield hydrogen index values ranging from 282 to 510 mg hc g toc with low oxygen index values consistent with type ii and mixed type ii iii kerogens the coal samples have vitrinite reflectance values in the range of 0 47 0 67 ro indicating immature to early mature initial oil window t max values range from 428 to 436 c which are good in agreement with vitrinite reflectance data the tertiary coals are humic and generally dominated by vitrinite with significant amounts of liptinite and low amounts of inertinite macerals good liquid hydrocarbons generation potential can be expected from the coals with rich liptinitic content 35 this is supported by their high hydrogen index of up to 300 mg hc g toc and py gc s 2 pyrograms with n alkane alkene doublets extending beyond c30 the tertiary coals are characterised by dominant odd carbon numbered n alkanes n c23 to n c33 high pr ph ratio 6 8 high t m t s ratio 8 16 and predominant regular sterane c29 all biomarkers parameters clearly indicate that the organic matter was derived from terrestrial inputs and the deposited under oxic condition

provenance and paleoenvironment of organic matter within the fika sediments in chad bornu basin northeastern nigeria an integrated organic geochemical and palynofacies approach abstract the upper cretaceous fika sediments in the chad bornu basin were characterised to define paleoenvironment and source of the organic matter using an integration of organic geochemical analyses and palynofacies observations the present day toc contents of the fika sediments are in the range of 0 41 2 37 wt while the hydrogen index hi values are largely below 200 mg hc g toc suggesting that the sediments generally have fair to good generative potential and contain mainly type iii and type iv kerogens this is supported by palynofacies observations whereby the kerogen is characterised by large amounts aom and phytoclasts the fika sediments have vitrinite reflectance and t max values in the range of 0 70 1 34 and 429 465 c respectively indicating early mature to late mature stage of oil window the level of organic maturation in fika sediments was further supported by the several biomarker maturity indicators biomarker distributions and palynofacies data provide evidence for a mixed aquatic algae and terrigenous organic matter input deposited in a marginally marine moderate salinity proximal setting with a strong influx of terrestrial plant under environmental conditions that were mostly suboxic compound specific isotopic analysis of n alkanes fraction were also used for the paleoenvironmental inferences the flat portion pattern of the n alkane profile between n c 21 and n c 26 in fika samples is an indication of marine environment and it shows that fika sediments consist of both terrestrial and marine organic matter deposited in fluvial deltaic to shallow marine settings