three dimensional velocity imaging of the kachchh seismic zone gujarat india abstract to understand the causative mechanism of the continued occurrence of earthquakes in kachchh gujarat for the last six years we estimated high resolution three dimensional vp vs and vp vs structures in the aftershock zones of the 2001 mw7 7 bhuj and 2006 mw5 6 gedi earthquakes we used 13 862 p and 13 736 s wave high quality arrival times collected from the seismograms of 2303 aftershocks recorded at 5 18 three component seismograph stations during 2001 06 seismic images revealed a marked spatial variation in the velocities from 20 to 14 in vp from 12 to 13 in vs and from 12 to 12 increase in vp vs in the 0 34 km depth range beneath the bhuj aftershock zone relatively more increase in vp than vs resulting in an increase in vp vs in the crust beneath the seismically active causative fault north wagad fault nwf zone of 2001 bhuj mainshock suggests a rigid mafic crust beneath the region they also delineate an increase of 8 in vp and 14 in vs and a decrease of 4 in vp vs in the almost vertical rupture zone of the 2006 gedi earthquake extending up to 12 km depth this high velocity body associated with the gedi mainshock is inferred to be a gabbroic intrusive the banni region and the wagad uplift are found to be associated with high velocity intrusive bodies inferred to be mafic extending from 5 to 35 km depth which might have intruded during the rifting in early jurassic 160 ma aftershock activity is mainly confined to the zones characterized by high vp high vs and low vp vs ratio which might be representing the strong competent and brittle parts of the fault zone intrusive bodies that could accumulate large strain energy for generating aftershocks for more than six years it is inferred that the crustal stress concentrations associated with the intrusive bodies are contributing significant perturbation to the crustal stress regime to generate the intraplate earthquakes in the kachchh rift zone a few patches of slow vp and vs and high vp vs between 10 to 30 km depth have also been detected on the causative 45 south dipping north wagad fault nwf for the 2001 mainshock which may be attributed to the fluid filled fractured rock matrix interestingly the 2001 bhuj mainshock hypocenter is found to be associated with such a low velocity patch thus it is inferred that the occurrence of 2001 bhuj mainshock might have facilitated by the presence of fluids at hypocentral depth

novel tricyclic and tetracyclic terpanes in tertiary deltaic oils structural identification origin and application to petroleum correlation abstract tricyclic terpanes of the cheilanthane series in crude oils and sediments are routinely used for geochemical correlation the cheilanthanes are particularly useful to identify crude oils derived from marine clastic or carbonate source rock as well as input to the source rocks from marine algal or terrigenous organic matter however they sometimes have limitations for the correlation of oils expelled from different source rocks that received similar organic matter e g oils from source rocks dominated by terrigenous organic matter novel non cheilanthane tricyclic terpanes consisting of c21 and c25 compounds and a c27 tetracyclic terpane were identified in oils from the assam india beaufort mackenzie canada and the niger nigeria deltas nmr data reveal that all three compounds have an oleanane type structure with rings c d and e intact while rings a and b have been degraded leaving a side chain attached to ring c in the case of the tricyclics and only a degraded a ring in the tetracyclic on the basis of occurrence nmr structure and co variance with oleanane abundance these new tricyclic and tetracyclic compounds are believed to form from a ring functionalised oleanoid precursors in angiosperm flowering plants the distribution of these compounds in representative oils from the niger delta accumulations permits separation of the oils into at least three distinct source rock organofacies

the oleananes origin maturation and limits of occurence in southern nigeria sedimentary basins oleananes occur within well defined age and paleogeographic boundaries in the sedimentary province of southern nigeria thus signifying that the biomarkers may be analogous to index fossils in anambra syncline lower benue trough the biomarkers are found in rocks which are as old as late upper cretaceous in tertiary niger delta the concentration composition and distribution of the oleananes in rocks and oils are determined mainly by palaeodepositional environment and thermal history and are independent of age and geographical location of specific samples oleanane content varies with increasing burial depth with peak concentration coinciding within rm range 0 4 0 6 implying early generation of hydrocarbons from the basin s typically resin rich kerogens it is evident that the oleanane content parameter is superior to the hopane and sterane isomerisation indices for monitoring thermal maturation in the delta and for differentiating paralic from paralic marine source facies as well as early from late generated oils

multiple frequency sh wave tomography of the western us upper mantle summary we estimate the sh wave velocity and attenuation structures of the western us upper mantle using the dense network of the usarray and new techniques we observe a multiple frequency data set of both traveltime and amplitude anomalies and interpret these with full 3 d finitefrequency sensitivity kernels amplitudes show stronger frequency dependence than traveltimes we perform a joint inversion on the measured traveltime and amplitude anomalies interpreting them in terms of velocity and attenuation heterogeneities aside from the expected clear division between the slow tectonically active region in the west and the fast craton in the east several interesting smaller velocity anomalies are observed the subduction along the cascades at 100 300 km depths shows lateral discontinuity with a slab hole absence of fast anomalies observed around 45 n the delaminated sierra nevada mountains root is observed to have sunk to 200 km depth the yellowstone plume seems to have an origin weak slow velocity anomalies near 1000 km depth but the plume conduit seems to be interrupted by a fast anomaly which is identified as a fragment of the farallon slab the s velocity model shows a trench perpendicular slab gap absence of fast anomalies at almost the same location as in the p model recently published by sigloch et al 2008 the methodological improvements described in the first paragraph have several benefits amplitude data help to sharpen the edges of narrow velocity heterogeneities in the shallow upper mantle the focusing effect from velocity heterogeneity dominates over that of attenuation and must be considered when interpreting amplitude anomalies in general velocity and attenuation heterogeneities correlate positively suggesting that temperature plays a major role in forming the anomalies

biomarkers of holocene buried conifer logs from bella coola and north vancouver british columbia canada abstract the biomarker compositions of a holocene seep oil liquefied resin originating from a buried log of douglas fir pseudotsuga menziesii from bella coola bc canada and a holocene pine wood pinus sp sample from north vancouver bc canada were analyzed using gas chromatography mass spectrometry gc ms the total extract of the bella coola sample contains the sesquiterpenoid derivative calamenene and diterpenoids of the labdane abietane pimarane and phyllocladane classes a novel series of successively degraded labdane derivatives labdan 15 oic acid norlabdanoic acids drimenoic acid was detected in the polar fraction and a diagenetic pathway is proposed aromatic abietanes are the major components in the neutral fraction the neutral fraction of the pine wood contains two sesquiterpenoids calamenene cadalene diterpenoids of the abietane pimarane isopimarane and kaurane classes and a series of steroids 18 norabieta 8 11 13 triene dehydroabietin is the major component among the predominantly aromatic abietanes based on the compositions of the terpenoids it is concluded that the diagenesis of the pine and douglas fir logs probably occurred under anaerobic conditions leading to reductive reactions such as decarboxylation of resin acids with concurrent oxidation reactions to form the aromatic derivatives

geology petrology and utilisation potential of some tertiary coals of the northeastern region of india abstract the coal bearing tertiary sediments of the northeastern region of india range in age from palaeocene to oligocene the coal deposits of meghalaya and the mikir and north cachar hills of assam contain generally thin seams of eocene age and were formed under stable shelf condition in peripheral platform areas the coal deposits of oligocene age occur in a narrow linear belt of overthrusts referred to as the belt of schuppen that extends from nagaland through assam to arunachal pradesh they were deposited in near shore deltaic wet forest swamps to marshy environments close to a geosynclinal trough the coal seams attain considerable thickness in the makum and namchik namphuk coalfields comparisons of coal type and rank variations in the eocene and oligocene coals indicate that the coals are broadly similar the coals are vitrinite rich 70 vol mineral matter free hereafter referred as mmf with moderate amounts of liptinite 8 vol mmf and inertinite 5 vol mmf the coals are high in volatile matter 38 57 dry mineral matter free basis hereafter referred as dmf sulphur 1 10 and hydrogen contents 4 9 dmf the carbon content of the coals ranges from 68 to 85 dmf the coals have caking properties in restricted zones the vitrinite reflectance of the oligocene coals r r 0 53 0 74 is slightly higher than that of the eocene coals r r 0 37 0 67 as per astm standard the eocene coals are classified as sub bituminous c to high volatile bituminous c and the oligocene coals as sub bituminous a to high volatile bituminous b microscopic examination of the coals shows a number of features which indicate that the northeastern coals may have generated hydrocarbons most of the eocene and oligocene coals are suitable for combustion and conversion e g liquefaction processes the coals with caking properties are being used at rates up to 5 10 in blends for metallurgical coke provided their sulphur content is below 3 and their ash content below 10

sedimentology palynostratigraphy and palynofacies of the late oligocene makum coalfield assam india a window on lowland tropical vegetation during the most recent episode of significant global warmth abstract the sedimentology palynofacies and pollen and spore assemblages together with observations on the preserved megaflora from the tirap coal mine assam india 27 17 20 n 95 46 15 e provide important insights into the composition and distribution of plant communities in a late oligocene tropical delta palaeolatitude approximately 18 n these insights take on additional significance because the late oligocene included the last significantly warm interval in earth s history before progressive neogene cooling to the present day icehouse the lower two thirds of a 188 m studied section represents lower delta plain environments with only a small degree of brackish water marine influence raised mires autochthonous swamps and allochthonous organic matter accumulations comprise the vitrinite rich high volatile bituminous b coals the upper third of the section represents upper delta plain environments with high sediment pass through here standing fossil forests attest to frequent inundation and recovery of the arborescent interfluve vegetation throughout the period of deposition of the studied section several 100 kyr sediment supply exceeded increases in accommodation space afforded by basin subsidence relative sea level rise a dominance of spores attributed to cyatheaceous and other fern taxa indicates that tree ferns and other pteridophytes were a major component of the vegetation throughout the environments represented by the section despite the absence of ferns in the megafossil record nypa and mangrove megaremains together with mangrove pollen and acrostichum spores attest to the presence of a mangrove community similar in composition to those of modern southeast asia palms and megathermal tree taxa such as those belonging to the malvaceae meliaceae alangiaceae anacardiaceae and pellicieraceae inhabited the interfluve and swamp forests perennial herbs of the family gunneraceae occur throughout the section palynofacies analysis shows a dominance of anoxic dysoxic environments with a small part of the lower part of the section exhibiting more oxic conditions associated with circumstantial evidence for mild marine possibly tidal influence most palynodebris fluoresce only weakly consistent with the relatively high rank for coals of this age a small number of reworked gondwanic permian grains suggest sediment erosion from the highlands to the north the late oligocene tropical delta vegetation has much in common with modern lowland wet megathermal forests from southeast asia however tree ferns appear more prevalent in the late oligocene

oil source correlation in tertiary deltaic petroleum systems a comparative study of the beaufort mackenzie basin in canada and the pearl river mouth basin in china abstract biomarker distributions in crude oil have been routinely used to investigate source rock character thermal maturity of migrated oil and lateral facies changes in the underlying source rocks in vertically drained basins case studies from tertiary deltaic systems that contain mixed oils from multiple source rocks in the beaufort mackenzie and pearl river mouth basins indicate that oil source correlation using the common fingerprint approach tends to favour the source that contains higher biomarker concentrations so biomarker concentrations as well as concentration independent yet source definitive parameters are needed to address the mass balance issues

geochemistry of crude oils from eastern indonesia high resolution geochemistry shows genetic relationships among 27 crude oils from eastern indonesia and suggests the ages and paleoenvironments of their source rocks oils inferred to originate from tertiary and triassic jurassic source rocks in the study occur north and south of 2is latitude respectively twenty oils mainly from irian jaya and sulawesi originated from tertiary marine marlstone source rocks that contained type ii iii kerogen deposited under suboxic conditions probably the upper miocene klasafet formation these low sulfur oils show high oleanane c26 24 nordia cholestane and pristane phytane ratios and 13c rich carbon isotope compositions high oleanane and 24 nordiacholestane ratios are diagnostic of tertiary oils and source rocks these oils account for about 16 of the estimated ultimate recoverable reserves in eastern indonesia

the paleogene vegetation and petroleum system in the tropics a biomarker approach abstract the present study investigates the biomarker signatures of sediments and crude oils to infer the paleovegetation from the two petroleum systems of assam basin eastern india they are classified as the paleocene middle eocene and the middle eocene oligocene petroleum systems the sediments are oil and gas prone with an early catagenetic stage of thermal evolution here we report tricyclic diterpanes such as rimuane pimarane rosane and isopimarane along with tetracyclic diterpanes ent beyerane phyllocladane kaurane from paleocene eocene coal bearing sediments and crude oils these diterpane biomarkers attest dominant contribution from conifers possibly from podocarpaceae and araucariaceae however diterpanes are not detected in oligocene sediments and oils crude oils from both paleocene eocene and oligocene reservoirs and organic rich sediments contain angiosperm biomarkers such oleanane and related triterpanes along with bicadinane a biomarker specific for the dipterocarpaceae family of angiosperms the equatorial position of india during early paleogene along with the presence of angiosperm signatures including dipterocarpaceae and gymnosperms reflect the emergence of tropical rainforest elements in eastern india absence of diterpenoids in oligocene samples and difference in angiosperm parameters from paleocene eocene samples suggests a change in source vegetation and organofacies

tertiary oils from upper assam basin india a geochemical study using terrigenous biomarkers abstract the upper assam basin in northeast india is a tertiary sub basin of the assam arakan basin hydrocarbons are present in the langpar formation upper palaeocene lakadong member of the sylhet formation lower eocene and the barail oligocene tipam lower miocene and girujan middle miocene formations in the basin a detailed study to understand the nature and origin of the oils from different stratigraphic horizons using terrigenous and other biomarkers has been carried out further the variation in maturities of oils occurring in different stratigraphic horizons has also been studied the study shows that rearranged oleananes oleananes and bicadinanes are present in these oils implying land plant input to their source rocks the oils have been classified into different groups using ratios of rearranged oleananes oleananes bicadinanes and steranes indicating presence of multiple source rocks in the basin with subtle variation in characteristics maturity studies show that oils from younger horizons barail tipam and girujan are more mature than oils from older horizons langpar and lakadong there is an apparent mismatch in maturity of oils as measured by different biomarker maturity parameters this is due to the mixing of two different charges of oils having different maturities and generated from two different source rock kitchens in the same reservoir principal component analysis pca of biomarker data has also been able to classify the oils into various groups a new parameter has been developed using ratios of rearranged oleananes for determining maturity of these oils

biomarker and n alkane isotope profiles for tertiary oils relationship to source rock depositional setting abstract biomarker and n alkane isotope profiles have been measured for 29 late cretaceous tertiary oils from se asia china papua new guinea new zealand and the u s a the results are interpreted with respect to six kinds of source rock depositional setting fluvio deltaic fd freshwater transitional tr lacustrine lac saline lacustrine sal marine deltaic md and marine carbonate mc a comparison of biomarker and n alkane isotope results suggests that parameters such as the oleanane hopane ratio may overestimate the higher plant contribution to marine oils the abundance of bicadinanes is much more variable than that of oleanane probably because of a specific association with the highly resinous dipterocarp hardwoods of se asia however traces do occur in an oil from outside the paleogeographic range of the dipterocarp family confirming that there is also a more general angiosperm source the bicadinane isomeric distribution is shown to depend on maturity leading to new maturity parameters which are resistant to even very heavy biodegradation retention indices based on the regular hopane series are provided for the main bicadinane and methyl bicadinane isomers and for a group of oleanane related triterpanes of unknown structure the presence of the latter compounds may indicate locally deposited as opposed to transported higher plant matter in the source source rock depositional setting is the primary control on the shape of the n alkane isotope profile with negatively sloping curves being characteristic of fd and tr oils and flat or positively sloping curves typical of marine oils the difference is probably related to the bacterial reworking of higher plant matter in the fd environment a slight isotopic anomaly at n c 17 correlates with the abundance of algal derived steranes and may indicate a minor marine contribution to the source of an fd oil

sesquiterpanes diterpanes and other higher terpanes in oils from the taranaki basin of new zealand abstract the bi tri and tetracyclic terpenoids in crude oils from the taranaki basin of new zealand have been studied the distribution of c14 c15 and c16 bicyclanes was essentially invariant amongst the various fields a suggestion is made that the proportion of rearranged to total drimanes may be related to maturity and the ratio of homodrimane to drimane may be related to depositional environment mass spectra are reported for a number of unidentified sesquiterpanes including possibly norbisabolane and bisabolane the distribution of bi tri and tetracyclic diterpanes was very similar to that of crude oils from the gippsland basin of south east australia the occurrence of rimuane was confirmed 8 h labdane was identified and 4 h 18 norisopimarane was tentatively identified isopimarane dominated the diterpane distribution of oils from the maui field in the south west of the basin and its abundance gradually diminished in a north westerly direction until it became a minor component of oil from the new plymouth field this trend coincided with an increase in the complexity of the triterpane distribution and with the oleanane content of the oils these northwards trends also followed the evolution of coal deposits in the region the diterpanes in these oils had the same structure as those which occur in extant trees of the araucariaceae and podocarpaceae which flourish in new zealand today and did so even more extensively in the past coal measures formed from forests of such trees are probably the source of the diterpanes a situation analogous to that in the gippsland basin of south eastern australia tricyclanes of the cheilanthane series were not detected in any of the taranaki oils lending support to the view that these tricyclanes occur most abundantly in oils derived from marine sources c24 tetracyclanes secotriterpanes occurred abundantly in all the oils as they do in terrigenous oils from other parts of the world

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

optical properties of some tertiary coals from northeastern india their depositional environment and hydrocarbon potential abstract in northeastern india the coalfields of arunachal pradesh assam and nagaland are disposed along a linear belt of overthrusts known as the belt of schuppen where tertiary strata have been folded and dispersed into a number of thrust slices the coal bearing sediments in this belt are associated with the baragolai and tikak parbat formations of the barail group oligocene in meghalaya the tertiary sediments were deposited on a stable shelf along the periphery of the shillong plateau they are almost undisturbed and sub horizontal in attitude the coal seams are associated with the sylhet tura formations palaeocene of the jaintia group the chemical properties of these coals show characteristics of both low on volatile matter content and high on moisture and calorific value ranks the coals have a low softening temperature and a high swelling index volatile matter hydrogen and sulphur contents besides having the highest tar yield among indian coals the syncrude produced from these coals shows similarities with the identical fraction of crude oil from nahorkatiya oilfield assam the coals from the belt of schuppen and meghalaya are non banded and bright in nature microscopically their humic components are strongly decomposed with a common to frequent association of framboidal pyrite and calcite concretions the coals are vitrinite rich 52 0 80 0 with moderate amounts of liptinite macerals 5 8 16 2 the inertinite content is low 4 6 11 0 to occasionally high 30 0 fluorescing vitrinite and liptinite macerals constitute 46 5 to 83 5 by volume m m f perhydrous vitrinite liptodetrinite and resinite are the most common fluorescing macerals the rank of the coal samples r 0 max 0 57 0 74 ranges between high volatile bituminous c and b stages the assam coals are higher in rank than those of nagaland and meghalaya in northeastern india during the palaeocene and oligocene epochs peat swamps formed in situ from tropical mangrove rich angiospermous forest vegetation the palaeocene coals in meghalaya were formed in estuaries or lagoons however the coal forming phase ceased shortly due to prolonged marine transgression the oligocene coals in the belt of schuppen were formed during a regressive phase in back water lagoons or brackish water swamps on a prograding delta complex the hydrocarbon potential mg ch g c org of the coal samples from northeastern india has been theoretically deduced on the basis of their kerogen types following mukhopadhyay et al 1985 the presumed hydrogen index varies from 250 to 430 and 300 to 470 mg ch g c org respectively for coals in the belt of schuppen and meghalaya evidence indicates that in arunachal pradesh assam and nagaland oil has been generated from kerogen types ii b and ii a in the oligocene mudstone siltstone shale association of the coal measures of barail group in meghalaya no oil is known so far nevertheless the predominance of kerogen types ii a and ii b in coals indicates a good oil potential in the palaeocene sediments of the jaintia group

contrasted distributions of triterpene derivatives in the sediments of lake caco reflect paleoenvironmental changes during the last 20 000 yrs in ne brazil lipid fractions extracted from sediment layers deposited in a small brazilian lake during the last 20 000 yrs were investigated by gas chromatography mass spectrometry considerable differences in the distribution and the amount of triterpene derivatives in the aliphatic as well as in the aromatic fractions were observed all along the series although no precise identification of these compounds was undertaken our interpretation of mass spectral data allowed us to discriminate between des a triterpenes mono and triaromatic derivatives of pentacyclic triterpenes and a series of compounds tentatively identified as diaromatic derivatives of tetracyclic triterpenes the largest compound diversity was found in the lowest levels of the series dated back to the end of the last glacial maximum when good preservation of terrestrial plant debris was ensured by rapid burial in a semi arid climate then except for a period corresponding to the younger dryas only des a lupane was detected in significant amounts the high predominance of des a lupane is interpreted to result from the development of a belt of eleocharis sp spike rush that filtered most of organic inputs from the catchment and was the site of des a lupane production and exportation towards the lake centre during the younger dryas a strong influx of des a lupane is attributed to the destruction of the spike rush belt consecutive to the lowering of the lake level under drier conditions the temporary destruction of this barrier allowed other triterpene derivatives to reach the lake the distinct dynamics of des a and aromatic triterpene derivatives under variable medium conditions led us to hypothesis that these two families of compounds derive from distinct pools that contributed differently to the sediment depending on environmental and climatic conditions des a lupane was most probably produced in sub aquatic conditions within the belt of spike rush conversely aromatic derivatives of triterpenes could have resulted from the degradation of their biological precursors within reducing micro environments in the catchment

terpenoid composition and botanical affinity of cretaceous resins from india and myanmar abstract fossil resins from the cretaceous sediments of meghalaya india and kachin myanmar burma were analysed using curie point pyrolysis gas chromatography mass spectrometry and thermochemolysis gas chromatography mass spectrometry to help elucidate their botanical source the major pyrolysis products and methyl esterified thermochemolysis products of both the resins were abietane and labdane type diterpenoids with minor amount of sesquiterpenoids the thermochemolysis products also included methyl 16 17 dinor callitrisate methyl 16 17 dinor dehydroabietate and methyl 8 pimaren 18 oate the latter two from just the myanmarese resin the exclusive presence of both labdane and abietane diterpenoids and the lack of phenolic terpenoids may suggest that the studied cretaceous resins were derived from pinaceae pine family conifers

aliphatic and aromatic triterpenoid hydrocarbons in a tertiary angiospermous lignite abstract the hydrocarbon biomarker assemlage of a liptinite rich early tertiary angiospermous lignite has been characterized the biomarker fistribution for the lignite confirms the low maturity and previous paleobotanic interpretations the aliphatic hydrocarbon fraction consists predominantly of n alkanes showing a strong odd carbon predominance and numerous de a triterpenoids and triterpenoids derived from higher plants bacterially derived triterpenoids were represented primarily by homohopanes and hopenes the aromatic hydrocarbon fraction contains a series of mono di and triaromatic de a triterpenoids and mono tri and tetraaromatic triterpenoids derived from higher plants the concentration and abundance of monoaromatic triterpenoids containing one to three additonal degress of unsaturation have not seen previously observed in a single deposit as such a diagenetic scheme for angiosperm derived triterpenoids is presented which confirms and extends previous hypothesis

chemostratigraphic evidence of higher plant evolution in the taranaki basin new zealand correlation between palynological and biomarker records of higher plant development during the cretaceous and paleogene in taranaki basin new zealand is good gymnosperms particularly podocarps were the chief members of coastal plain swamp flora during the late cretaceous and contributed significant quantities of diterpanes often dominated by isopimarane to organic rich sediments angiosperms increased in relative abundance through the paleocene and became the dominant higher plants in the eocene their contributions to coaly sediments are characterized by various triterpanes particularly 18 h oleanane and its c24 a ring degraded counterpart this change in dominance of higher plant groups can be followed by the use of an angiosperm gymnosperm index agi based on the relative concentrations of selected triterpanes and diterpanes in mz 191 and mz 123 mass chromatograms plant biomarker distributions do not provide as precise age indications as do pollen assemblages but they may be more representative of the vegetation growing in a particular area of a peat swamp

petroleum geochemistry of a part of upper assam basin india a brief overview abstract the upper assam tertiary sedimentary basin is an important petroleum province with reservoir rocks ranging in age from upper paleocene to miocene the bulk of the oil production is from the barail oligocene and tipam miocene formations promising hydrocarbon pools have been discovered recently in upper paleocene lower eocene formations prolific source rocks occur within the barail oligocene formation langpar formation upper paleocene and lakadong theria member of sylhet formation of upper paleocene lower eocene age the source rocks contain predominantly type ii organic matter and are thermally immature to early mature biomarker ratios indicate the dominance of land plant derived kerogen the barail and tipam oils have moderate gravity and significant wax contents the physical and chemical characteristics of the paleocene eocene crude oil is similar to that produced from younger horizons within the basin with the exception of minor quantities of heavy viscous crude oils observed in a few wells multivariate analysis including principal components analysis and factor analysis of fluorescence data and principal components analysis of biomarker data indicate that the barail oligocene and tipam miocene oil have been derived from barail source rocks with a possible contribution from eocene source rocks these preliminary studies have not provided conclusive evidence for the source of the eocene oils although geological factors indicate that the source rocks are probably the interbedded shales coals occurring within the upper paleocene lower eocene sediments

molecular composition and chemosystematic aspects of cretaceous amber from the amazonas araripe and reconcavo basins brazil amber occurrences in brazil are rare in this regard the molecular composition of three such fossil resin samples from brazilian cretaceous sedimentary basins has been analyzed to determine the botanical origin of the resins the samples were collected from the amazonas alter do chao formation araripe santana formation crato member and reconcavo maracangalha formation caruacu member basins the mono sesqui and diterpenoids in the extracts were used as chemosystematic markers when compared with terpenoids in extant conifers the compounds were mainly diterpenoids and their degradation products from the labdane podocarpane pimarane and isopimarane classes in addition to paraffins methoxyphenols and carboxylic acids tetracyclic diterpenoids such as phyllocladane kaurenol and kauranol were also present the biomarker compositions are certainly typical for conifers and given the absence of triterpenoids and diterpenoids such as ozic acid angiosperms can be excluded as a botanical source the absence of phenolic diterpenoids ferruginol totarol and their derivatives excludes podocarpaceous affinities for the ambers from the amazonas and araripe basins the fossil records of the embedding sediments e g araucariaceae pollen and leaves support the proposal of an araucariacae origin for these ambers but cupressaceae and cheirolepidiaceae cannot be excluded on the other hand the presence of phyllocladane and kaurane derivatives is evidence for araucariaceae or podocarpaceae origins for the amber from the reconcavo basin but cupressaceae cannot be excluded