sedimentary pyrite formation an update sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time the amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter dissolved sulfate and reactive detrital iron minerals organic matter appears to be the major control on pyrite formation in normal non euxinic terrigenous marine sediments where dissolved sulfate and iron minerals are abundant by contrast pyrite formation in non marine freshwater sediments is severely limited by low concentrations of sulfate and this characteristic can be used to distinguish ancient organic rich fresh water shales from marine shales under marine euxinic conditions sufficient h2s is produced that the dominant control on pyrite formation is the availability of reactive iron minerals calculations based on a sulfur isotope model indicate that over phanerozoic time the worldwide average organic carbon to pyrite sulfur ratio of sedimentary rocks has varied considerably high cs ratios during permo carboniferous time can be explained by a shift of major organic deposition from the oceans to the land which resulted in the formation of vast coal swamps at that time low cs ratios compared to today during the early paleozoic can be explained in terms of a greater abundance of euxinic basins combined with deposition of a more reactive type of organic matter in the remaining oxygenated portions of the ocean the latter could have been due to lower oceanic oxygen levels and or a lack of transportation of refractory terrestrial organic matter to the marine environment due to the absence of vascular land plants at that time

incorporation of ca isotopes in carapaxes of marine ostracods abstract we studied mg ca sr ca and ca isotope ratios of ostracod carapaxes from surface sediments retrieved during research cruises to the southern and equatorial eastern atlantic collected specimens originate from water depth between 30 and about 5000 mbsl and cover bottom water temperatures between 0 and 23 c analysed taxa include buntonia sp cytherella sp henryhowella sp krithe sp poseidonamicus sp and ruggieria sp calcium isotope ratios of the studied specimens are in the overall range of other marine calcifiers and show a variability of about 0 75 over a temperature range of 20 c there is no overall linear relation between temperature and ca isotope fractionation but some species show a maximum 44 40ca at intermediate temperatures mg ca and sr ca agree well with values of previously published carapaxes demonstrating large inter and intra species variability and different responses to bottom water temperatures magnesium is highly variably distributed within the carapax with mg enrichment in the inner part of the shell of most taxa this enrichment is independent from the incorporation of sr which shows less variability within the carapax the ca isotope vs sr ca systematic in the ostracods deviates from inorganic calcite and foraminifers the ostracod array is most likely controlled by either mixing of material originating from a precursor phase and newly grown calcite or rayleigh type fractionation during precipitation from a restricted fluid reservoir indicating varying degrees of ca and sr consumption during calcite precipitation the different slope of the ca isotope vs sr ca relation shown by the ostracods compared to those of inorganic calcite and foraminifers opens a new approach for the determination of ca isotope and sr ca ratios of past ocean water

reconstructing past seawater mg ca and sr ca from mid ocean ridge flank calcium carbonate veins proxies for past seawater chemistry such as mg ca and sr ca ratios provide a record of the dynamic exchanges of elements between the solid earth the atmosphere and the hydrosphere and the evolving influence of life we estimated past oceanic mg ca and sr ca ratios from suites of 1 6 to 170 million year old calcium carbonate veins that had precipitated from seawater derived fluids in ocean ridge flank basalts our data indicate that before the neogene oceanic mg ca and sr ca ratios were lower than in the modern ocean decreased ocean spreading since the cretaceous and the resulting slow reduction in ocean crustal hydrothermal exchange throughout the early tertiary may explain the recent rise in these ratios

hydrocarbon generation and expulsion characteristics of the source rocks in the third member of the upper triassic xujiahe formation and its effect on conventional and unconventional hydrocarbon resource potential in the sichuan basin abstract the third member of the upper triassic xujiahe formation t3x3 is a typical source reservoir cap unit for natural gas exploration in the sichuan basin however most previous studies mainly focused on the t3x3 as a source rock ignoring its role as a reservoir as a result the evaluation of hydrocarbon resource potential was not accurate this study established a hydrocarbon generation and expulsion model through analyzing the geological and geochemical characteristics of the t3x3 source rocks and calculated the resource potential of conventional gas tight gas and shale gas systematically with combining the lower boundary of buoyancy dominated accumulation lbba the results indicated that the thickness of the source rocks dominated by mudstone was distributed widely with an average value of more than 45 m the sedimentary environment was salty lacustrine deposits they have a high content of total organic carbon toc with an average value of 4 80 wt the kerogen is mainly type iii with minor type ii and the thermal evolution has entered the high to over mature stage the hydrocarbon generation threshold was determined to be 0 5 ro while the hydrocarbon expulsion threshold and the lbba were determined to be 0 83 ro and 1 12 ro respectively the efficiency of hydrocarbon expulsion was relatively high with an average of about 56 also the maximum hydrocarbon generation and expulsion intensity reached to 110 108 m3 km2 and 53 108 m3 km2 the amounts of hydrocarbon generation expulsion and residual associated with the t3x3 source rocks were 125 68 1012m3 70 38 1012m3 and 55 30 1012m3 respectively under the criterion condition of the lbba the conventional gas resource was 7 21 1010m3 the tight gas resource was 294 34 1010m3 and the shale gas resource was 2488 50 1010m3 it indicated good prospects for exploration

mesozoic and cenozoic deformation inferred from seismic stratigraphy in the southwestern intracontinental palmyride fold thrust belt syria this paper was published in the geological society of america bulletin the geological society of america retains the copyright to this paper geological society of america p o box 9140 boulder co 80301 9140 usa see also http www geosociety org http atlas geo cornell edu syria chaimov gsa bull 1992 html

2d basin modeling study of the binak trough northwestern persian gulf iran abstract the northwestern part of the persian gulf is one of the most prominent hydrocarbon exploration and production areas oilfields are located in structural highs formed around the cenomanian depression known as binak trough to evaluate the highly variable source rock maturity timing of hydrocarbon generation as well as migration pattern and the remaining hydrocarbon potential of the early cretaceous source rocks burial and thermal histories were constructed for four production wells and one pseudo well in addition two cross sections covering the depression and the structural highs around the trough were investigated by 2d basin modeling to provide a better regional overview on basin evolution the modeling results indicate that whereas the cretaceous source rocks are immature or early mature at the location of oilfields they reached sufficient maturity to generate and expel considerable amounts of hydrocarbons in the binak depression the main phase of oil generation and expulsion from the cretaceous source rocks is relatively recent and thus highly favorable for the conservation of hydrocarbon accumulations trap charging occurred through the late miocene to pliocene after the zagros folding 2d models predict that the albian source rock still has significant hydrocarbon generation potential whereas the lower neocomian source rock has reached already a high transformation ratio within the deep kitchen area oil migration occurs in both lateral and vertical directions this migration pattern could explain the distribution of identified oil families in the northwestern part of the persian gulf

map based uncertainty analysis for exploration using basin modeling and machine learning techniques applied to the levant basin petroleum systems eastern mediterranean abstract the levant basin of the east mediterranean region contains a biogenic petroleum system and possibly an underlying thermogenic system the application of a new map based uncertainty and sensitivity analysis that integrates a large set of geological parameters demonstrates that a connection between an upper cretaceous thermogenic petroleum system and the shallower oligo miocene reservoirs is highly possible in the southern part of the basin offshore israel and southern lebanon where hydrocarbon fluids are generated from the campanian source rock and charge the overlying oligo miocene reservoir interval through faults estimates of volumes of expelled hydrocarbons combined with regional analysis of the eocene top seal integrity indicates that the most prospective zones correspond to the southern offshore lebanon and offshore israel in the northern part of the levant basin offshore central and northern lebanon petroleum fluids potentially generated by the campanian source rocks remain trapped under the eocene seal or they migrate towards the margins of the basin our approach is based on applications of machine learning techniques and robust statistical analyses to petroleum systems modeling focusing on spatial uncertainty analysis it may be used on similar frontier or emerging hydrocarbon provinces to help de risking the petroleum systems

mg ca sr ca and ca isotope ratios in benthonic foraminifers related to test structure mineralogy and environmental controls we analysed mg ca sr ca and ca isotope ratios of benthonic foraminifers from sediment core tops retrieved during several research cruises in the atlantic ocean in order to improve the understanding of isotope fractionation and element partitioning resulting from biomineralisation processes and changes in ambient conditions species include foraminifers secreting tests composed of hyaline low magnesium calcite porcelaneous high magnesium calcite as well as aragonite our results demonstrate systematic isotope fractionation and element partitioning patterns specific for these foraminiferal groups calcium isotope fractionation is similar in porcelaneous and hyaline calcite tests and both groups demonstrate the previously described anomaly with enrichment of heavy isotopes around 3 4 degrees c gussone and filipsson 2010 calcium isotope ratios of the aragonitic species hoeglundina elegans on the other hand are about 0 4 parts per thousand lighter compared to the calcitic species which is in general agreement with stronger fractionation in inorganic aragonite compared to calcite however the low and strongly variable sr content suggests additional processes during test formation and we propose that transmembrane ion transport or a precursor phase to aragonite may be involved porcelaneous tests composed of high mg calcite incorporate higher amounts of sr compared to hyaline low mg calcite in agreement with inorganic calcite systematics but also porcelaneous tests with reduced mg ca show high sr ca while calcium isotopes sr ca and mg ca in benthonic foraminifers primarily appear to fractionate and partition with a dominant inorganic control delta ca 44 40 temperature and growth rate dependencies of benthonic foraminifer tests favour a dominant contribution of light ca by transmembrane transport relative to unfractionated seawater ca to the calcifying fluid thus controlling the formation of foraminiferal delta ca 44 40 and sr ca proxy signals c 2015 elsevier ltd all rights reserved less

comparative study of organic matter preservation in immature sediments along the continental margins of peru and oman part i results of petrographical and bulk geochemical data abstract detailed petrographical and bulk geochemical investigations of organic matter om have been performed on sediments deposited below or close to upwelling areas offshore peru odp leg 112 sites 679 681 688 and oman odp leg 117 sites 720 723 724 in order to obtain a quantitative understanding of its accumulation and degradation microscopical as well as nanoscopical investigations reveal that the om in sediments affected by upwelling mechanisms mainly up to 98 consists of unstructured amorphous organic aggregates without any apparent biological structures in sediments which are not or to a lesser extent affected by upwelling site 720 terrestrial om predominates organic carbon toc contents are highly variable and range between 9 8 in sediments deposited below upwelling cells and 0 2 in sediments outside the upwelling zone the toc sulphur ratios of the sediments scatter widely the samples from the deep water locations sites 688 and 720 show c s ratios of normal marine sediments whereas at the other locations no correlation or even a negative correlation between sulphur and toc concentration exists in most of the upwelling influenced sediments om contains a significant amount of sulphur the incorporation of sulphur into the om followed microbial sulphate reduction and occurred in the upper meters of the sedimentary column below om is still present in vast amounts and relatively hydrogen rich but is nevertheless non metabolizable and becomes the limiting factor for bacterial sulphate reduction according to mass balance calculations 90 99 of the om produced in the photic zone was remineralized and 1 3 was consumed by microbial sulphate reduction the aerobic and anaerobic processes have greatly affected degradation and conservation of om

interlaboratory study for coral sr ca and other element ca ratio measurements the sr ca ratio of coral aragonite is used to reconstruct past sea surface temperature sst twenty one laboratories took part in an interlaboratory study of coral sr ca measurements results show interlaboratory bias can be significant and in the extreme case could result in a range in sst estimates of 7 c however most of the data fall within a narrower range and the porites coral reference material jcp 1 is now characterized well enough to have a certified sr ca value of 8 838 mmol mol with an expanded uncertainty of 0 089 mmol mol following international association of geoanalysts iag guidelines this uncertainty at the 95 confidence level equates to 1 5 c for sst estimates using porites so is approaching fitness for purpose the comparable median within laboratory error is 0 5 c this difference in uncertainties illustrates the interlaboratory bias component that should be reduced through the use of reference materials like the jcp 1 there are many potential sources contributing to biases in comparative methods but traces of sr in ca standards and uncertainties in reference solution composition can account for half of the combined uncertainty consensus values that fulfil the requirements to be certified values were also obtained for mg ca in jcp 1 and for sr ca and mg ca ratios in the jct 1 giant clam reference material reference values with variable fitness for purpose have also been obtained for li ca b ca ba ca and u ca in both reference materials in future studies reporting coral element ca data should also report the average value obtained for a reference material such as the jcp 1

possible evidence for a large decrease in seawater strontium calcium ratios and strontium concentrations during the cenozoic article i nfo few constraints exist on the major element chemistry of ancient oceans turritellid marine snails precipitate aragonitic shells and are abundant in the cenozoic fossil record and therefore may be ideal for reconstructing past seawater chemistry here we report strontium to calcium sr ca ratios of modern and early cenozoic turritellid shells that still retain an aragonitic mineralogy by applying partition coefficients determined from modern specimens to data for paleocene and eocene shells we calculate paleo seawater sr ca values the high sr ca values recorded in fossil shells may imply that seawater sr ca ratios varied from at least 9 5 15 2 mmol mol much higher than modern average seawater values 8 6 mmol mol high paleo seawater sr ca ratios may indicate that substantial changes in the biogeochemical cycling of sr have occurred over the past 37 million years a decrease in seawater strontium concentrations could have arisen from an increase in the proportion of weathered radiogenic silicate rocks relative to carbonates reducing the riverine flux of strontium to the oceans or changes in the exposure and erosion of aragonitic carbonates on tropical shelves due to variations in sea level

calcium isotope fractionation in ikaite and vaterite abstract we investigated the isotopic composition of calcium in the metastable calcium carbonate polymorphs vaterite and ikaite the synthetic vaterite precipitates show a smaller degree of ca isotope fractionation than calcite or aragonite at comparable temperatures and revealed no significant temperature sensitivity between 10 and 50 c ikaite the water bearing ca carbonate modification caco 3 6h 2 o was precipitated at 2 c in controlled laboratory experiments and in addition recovered from marine sediments and sea ice synthetic and natural ikaites show similar values of ca isotope fractionation in general ikaite is less depleted in heavy isotopes compared to calcite or aragonite at low temperatures the observed offset of vaterite and ikaite to calcite or aragonite precipitated at similar temperatures is presumably mainly related to differences in precipitation rates and regimes which seem however to be typical for the growth of these carbonate minerals small differences in ca isotope ratios of naturally formed ikaites from different locations seem to be related to different geochemical conditions in the respective sediment settings

control of the preservation of organic matter by productivity and sulphate reduction in kimmeridgian shales from dorset uk abstract the kimmeridgian shales of dorset uk have a very wide range of total organic carbon toc content and hydrogen index hi these cyclic changes of organic carbon accumulation are usually interpreted in terms of biomass changes induced by variations in productivity the influence of such variations on the intensity of sulphate reduction and consequently on the preservation of organic carbon were studied the pyrite content does not reflect the full extent of sulphate reduction for sediments with a toc content greater than 10 when easily reducible iron is no longer available h 2 s is preferentially fixed as organic compounds in algal bodies a sulphate reduction index sri initial c org residual c org was calculated for each sediment on the basis of the sulphate reduction reaction stoichiometry and a drastic change in sulphate reduction intensity was seen for toc contents of about 10 above this value the sri is low and decreases with increasing toc content the sediments are rich in organic carbon composed of well laminated stacked algal bodies and were probably deposited at an oxygen depleted water sediment interface in this instance the quality and the amount of organic matter buried depends directly on the organic fluxes towards the redox interface it is assumed that the high relative input of organic matter which can be metabolized exceeds the availability of sulphate in the pore waters so that part of it escapes sulphate reduction and is probably degraded by other processes methanogenesis for toc contents less than 10 the sri is higher and variable the sediments show traces of burrowing and the depositional conditions are thought to be dysaerobic it is proposed that under such conditions bioturbation brings both sulphate and reducible iron into the sediment and that sulphate reduction mainly expressed by the presence of pyrite consumes all the available organic matter which can be metabolized the strong variability in the intensity of sulphate reduction depends on various parameters such as the genetic type of planktonic organic matter the method of transportation to the sediment and possibly the earlier oxic degradation during transportation

petroleum prospects of lebanon some remarks from sedimentological and diagenetic studies of jurassic carbonates abstract only seven exploration wells have been drilled in lebanon to date failing to encounter oil or gas in commercial quantities and to penetrate into unexposed pre jurassic reservoirs this paper shows that the sedimentological and diagenetic characteristics of the major lebanese jurassic carbonate rock unit the kesrouane formation thickness 1000 m negate jurassic hydrocarbon prospectivity in northern mount lebanon the jurassic platform in this region was subjected to a first emergence and invasion by meteoric waters in the late jurassic causing a pervasive cementation a second phase of uplift and meteoric flushing occurred in the cenozoic thus only the areas located far from the jurassic and post cretaceous phreatic realms e g offshore tripoli nw lebanon may have been less affected by meteoric diagenesis and still provide promising prospects a 1993 seismic survey offshore tripoli confirmed the presence of late triassic evaporites in northern lebanon this also adds confidence to the results of the nahr ibrahim electrical survey which earlier suggested the presence of these evaporites in the subsurface of central lebanon the pre jurassic sequence hence is sealed and protected from the meteoric invasion observed in the overlying jurassic rocks accordingly the qartaba horst structure central northern lebanon would be equally if not more attractive for a pre jurassic play

a common source rock for egyptian and saudi hydrocarbons in the red sea the northern red sea area hosts a classic triple junction of the red sea gulf of aqaba and gulf of suez rifted basins the sedimentary succession here can be divided into prerift pre miocene and synrift miocene and post miocene megasequences the prerift section has been penetrated in only a few wells drilled on the western egyptian side of the red sea whereas the synrift section is known on both the egyptian and the saudi sides of the red sea although the synrift units on both sides of the water are similar in facies thicknesses and depositional environments they have different stratigraphic nomenclatures the northern red sea consists of elongated troughs separated by elongated structural highs both of which trend northwest southeast gulf of suez trend these highs are dissected by cross elements trending northeast southwest gulf of aqaba trend and east northeast west southwest and are looked upon as strike slip faults dislocating these highs identified rich source rocks are present in the upper senonian carbonates the sudr and duwi formations on the western side of the sea the early miocene rudeis formation burqan group and the middle miocene kareem and belayim formations maqna group the pre miocene and the early miocene source rocks host oil prone kerogen whereas the middle and late miocene source rocks contain oil and gas prone kerogen all of these source rocks are sufficiently mature copyright 1997 the american association of petroleum geologists all rights reserved 1manuscript received january 18 1996 revised manuscript received october 11 1996 final acceptance march 21 1997 2faculty of science uae university p o box 17551 al ain united arab emirates we are especially grateful to the egyptian general petroleum corporation for supplying the materials and the necessary data on which the present work is based and the permission to publish it we also thank c g st c kendall and a e m nairn who read the early draft of this paper and offered valuable comments thanks to aapg reviewers d waples r j murris w maze and an anonymous reviewer for their constructive comments which we have used to improve our paper we acknowledge g cole bhp petroleum for granting permission to use some of his previous work

late cretaceous upwelling system along the southern tethys margin israel interrelationship between productivity bottom water environments and organic matter preservation organic rich upper cretaceous sequences in israel were deposited in an extensive highly productive upwelling linked system which prevailed along the southern tethys margin and lasted for 19 m y santonian to late maastrichtian an understanding of the spatial and temporal characteristics of this system was gained through detailed paleontological and geochemical analyses of subsurface sequences in two basins in israel representing an outer shefela and an inner zin facies belt the nature of the upwelling system and its effect on the sedimentary record is related to two basic environmental parameters namely paleoproductivity intensity and oxygen levels at the bottom the assessment of these parameters and their interrelationship has been performed through the development of paleontological foraminiferal criteria which are independent of the organic matter content following the establishment of these criteria it is concluded that the productivity reached its maximum intensity during the late campanian which was also the time of most notable differentiation between the center of the upwelling system in the inner belt and the less intense conditions in the outer basin this distribution is expressed in varied lithology organic rich carbonates phosphorites and siliceous rocks at the core of upwelling and a uniform lithology organic rich carbonates at the margin of this system the uniform lithology of the maastrichtian in both basins composed of organic rich carbonates is ascribed to a gradual weakening of productivity the bottom conditions in the inner belt during the late campanian the time of maximum surface productivity were near anoxic changing to more aerated dysaerobic conditions during the early maastrichtian in the outer belt a more aerated bottom dysaerobic prevailed throughout the late campanian to late maastrichtian the elevated organic matter content in both basins reflects the overall environment of high productivity its actual variations however seem to be unrelated to changes in surface productivity and bottom oxygen levels

formation of immature asphalt from organic rich carbonate rocks i geochemical correlation abstract the formation of low maturity asphaltic oils immature asphalts from carbonate source rocks was investigated the senonian bituminous rocks sbr in israel are organic rich carbonate rocks that were deposited in a high productivity environment and they are part of a sedimentary sequence that also contains cherts and phosphorites the sbr were studied in different basins and the samples are from outcrops and three deep drillholes the bitumen contents of the rocks are exceptionally high up to 700 mg g c org and immature asphalts are found to be associated with them geochemical analysis indicates that the bitumens are indigenous to the host sbr and the associated asphalts are bitumens that have migrated a short distance with negligible chemical fractionation the high heteroatom content of the kerogens up to 30 in the sbr is suggested as a possible cause of the generation of asphaltic oils in an early stage of maturation

calcium isotope ratios in calcitic tests of benthic foraminifers abstract we analysed ca isotope ratios of the infaunal foraminiferal species cassidulina laevigata elphidium spp gyroidinoides spp and uvigerina peregrina as well as the epifaunal cibicidoides wuellerstorfi over a depth temperature gradient the calcium isotope ratios of the benthic foraminifers tests show a distinct anomaly around 4 c this anomaly is observed in both epi and infaunal species but there are also characteristic differences between both the 44 40 ca characteristics of benthic foraminifers may be explained by the interference of temperature and carbonate chemistry of the fluid on ca isotope fractionation we suggest that ca isotope composition of benthic foraminifer tests is dominantly controlled by temperature at temperatures higher than 5 c while in the temperature range below 5 c calcite saturation cc becomes an increasingly important controlling factor due to the non linear shape of the cc 44 40 ca relation of actively transported calcium the potential applicability of ca isotope ratios in benthic foraminifers for reconstruction of either temperatures or 44 40 ca sw is limited by the complex fractionation pattern below 5 c however due to the minor temperature dependence in the temperature range above 5 c benthic foraminifers might provide a possible alternative archive for 44 ca sw avoiding some uncertainties associated with planktic records relocation habitat calcification depth short time climate variability as long as a defined bottom water temperature above 5 c can be secured

calcium isotope fractionation upon experimental apatite formation abstract carbonated hydroxy apatite ca10 b nh4 k na 2b po4 6 y co3 2x 3 2 y oh 2 2x chap was synthesized in batch type experiments by mixing of calcium ca and phosphate bearing aqueous solutions and the transformation of calcite powder in aqueous solution between 11 and 65 c compositional changes of the mother solution and solid phase products were followed by powder xrd scanning electron microscopy sem edx raman spectroscopy and elemental analysis it was found that the transformation at ph values between 7 5 and 7 9 occurs via the dissolution of calcite followed by the precipitation of chap in the mixing approach crystallization of chap took place via precipitation of metastable brushite cah po4 2h2o as precursor phase that was further transformed into apatite calcium isotope fractionation led to an enrichment of the light isotope by about 0 5 to 1 1 in the solid chap compared to the aqueous solution consistently in all experimental approaches essentially independent of temperature in some experiments metastable brushite formed prior to transformation to chap and showed a reduced fractionation compared to the chap the observed ca isotope fractionation into the chap lattice resembles that of natural phosphorites and lies within the range of recently published experiments

north atlantic deepwater temperature change during late pliocene and late quaternary climatic cycles variations in the ratio of magnesium to calcium mg ca in fossil ostracodes from deep sea drilling project site 607 in the deep north atlantic show that the change in bottom water temperature during late pliocene 41 000 year obliquity cycles averaged 1 5 c between 3 2 and 2 8 million years ago ma and increased to 2 3 c between 2 8 and 2 3 ma coincidentally with the intensification of northern hemisphere glaciation during the last two 100 000 year glacial to interglacial climatic cycles of the quaternary bottom water temperatures changed by 4 5 c these results show that glacial deepwater cooling has intensified since 3 2 ma most likely as the result of progressively diminished deepwater production in the north atlantic and of the greater influence of antarctic bottom water in the north atlantic during glacial periods the ostracode mg ca data also allow the direct determination of the temperature component of the benthic foraminiferal oxygen isotope record from site 607 as well as derivation of a hypothetical sea level curve for the late pliocene and late quaternary the effects of dissolution on the mg ca ratios of ostracode shells appear to have been minimal

landscape evolution of the five islands of south louisiana scientific policy and salt dome utilization and management abstract the five islands of south central louisiana are piercement type salt domes uplifted from several kilometers depth as the surrounding strata experiences regional subsidence in general the domes are nearly circular in plan with maximum land surface elevations 23 52 m asl geomorphic evidence of salt induced uplift includes surface lineations aligned gullies excessively steep land surface topography and shear fractures in surficial sediments evidence of subsidence includes sinkhole ponds a few hectares in area broad topographic saddles over tens of hectares in size and kilometer scale collapse structures on each of the five islands peoria loess and silty colluvium bury a paleosol developed in the late pleistocene prairie complex of the lower mississippi valley the loess represents a single genetic unit of eolian origin is typically thickest on lower side slopes and is thin or absent on ridge crests the silty colluvium around the perimeter of the islands is a reworked loess derived from higher elevations shear fractures with high angle average dips occur in both peoria loess and the prairie complex conjugate shear pairs probably develop from extensional stress associated with vertical uplift of the underlying salt prairie complex deposition and initial soil development in a low relief alluvial plain of the mississippi river predates the latest emergence of the five islands loess and colluvial stratigraphy indicate that the domes were emergent during loess deposition gully incision shearing of quaternary sediments and the distribution of colluvium indicate continued uplift after loess deposition sinkholes and collapse structures are influenced by salt dissolution and corrasion whereas broad subsidence areas and topographic saddles form over areas of structural weakness within the salt five islands landscape evolution is controlled by the interaction of driving and resisting forces that operate over various time scales diapiric uplift is a driving force of net upwards motion and the external and internal salt dome hydrology are driving forces of solution and corrasion the structure and lithology of the internal salt stocks and the surrounding sediments are heterogeneous and have variable strength collectively this interaction produces both uplift and subsidence features across the salt dome landscape resource use at the five islands correlate with instability of both underground facilities and the surface landscape uplift of the five islands has continued since at least the late pleistocene is probably still active at present and periods of tectonic and geomorphic instability are possible in the future sediments overlying salt domes record discrete periods of surface uplift and periods of episodic and incremental subsidence that is common where salt domes pierce surficial sediment the rate magnitude and pattern of landscape modification by salt domes have implications for the safe utilization of mineral extraction and geostorage facilities geomorphic evaluation of salt dome landscapes can help to develop policies that ensure safe salt dome utilization salt dome resource planning should include detailed characterization of internal and external stratigraphy and structure modeling of geomorphic soil and rock mechanic and hydrologic processes routine and emergency planning at operating facilities and closure and post closure plans

polyphase thermal evolution in the infra cambrian ara group south oman salt basin as deduced by maturity of solid reservoir bitumen petrographic and organic geochemical analyses on solid reservoir bitumen from the late precambrian to early cambrian ara group indicate polyphase thermal evolution in the south oman salt basin sosb the ara group constitutes a complex petroleum system in the deep subsurface 3 5 km of interior oman salt diapirs encase isolated partly highly overpressured carbonate bodies intra salt stringers which represent a predominantly self charging hydrocarbon system a large number of stringer cores show that reservoir quality is decreased by the presence of solid reservoir bitumen by using different microscopy techniques this solid reservoir bitumen has been identified within pores pore throats and microfractures of the carbonates solid bitumen reflectance measurements brr were converted to vitrinite reflectance vrr using a new improved calibration vitrinite reflectance geothermometry shows that maximum paleo temperatures have a highly heterogeneous distribution paleo temperatures of 380 c were obtained from coke like solid reservoir bitumen which most likely formed from thermal cracking of oil in our model this process is related to hydrothermal fluids deriving from deeper pre salt strata of the sosb which entered the intra salt carbonate stringers during times of basement tectonic activity via hydrofractures this caused the formation of high maturities pyrobitumens in close vicinity to the fractures and precipitation of migrabitumens with increasing distance to the ht source which is supported by the geochemical composition of the solid reservoir bitumens the influx of these fluids into the carbonate stringers is considered to represent a major contribution to their strong overpressures 2007 elsevier ltd all rights reserved

paleoenvironments of the latest cretaceous oil shale sequence southern tethys israel as an integral part of the prevailing upwelling system abstract the late cretaceous succession in israel is part of an extensive high productivity upwelling regime that persisted over 20 m y in the southern margins of tethys the deposition of a 40 m thick organic rich carbonate oil shale sequence in the negev israel indicates a major change in the evolution of this high productivity regime and reorganization of the marine ecosystem during the latest campanian early maastrichtian time the main objective of this study was to reconstruct changes in surface water productivity and seafloor oxygenation during the deposition of the oil shale member osm and transitions with the underlying phosphate and overlying marl members using high resolution records of planktic and benthic foraminifera and total organic carbon toc content the updated age of the osm determined by integrating planktic foraminifera calcareous nannofossils and inoceramids suggests that this sequence spans a maximum of 1 85 m y from 71 6 to 69 85 ma with a sedimentation rate of at least 2 4 cm kyr five distinct planktic p types and benthic b type foraminiferal assemblages were distinguished in the studied sequence the change from p type 5 to p type 1 along the sequence correlates with a distinct decrease in toc content 18 0 0 1 wt and signifies an upward decline in surface productivity based on this relationship it was inferred that species of globigerinelloide s principally globigerinelloides asper are the best tracers for extreme eutrophic surface water whereas heterohelicids are associated with more mesotrophic conditions the transition in time from assemblages b types 5 to 1 mainly reflects a change from the predominance of praebuliminids and neobuliminids to a more diversified rotaliid dominated assemblage indicating an increase in bottom water aeration the appearances of planktic foraminifera coincident with the establishment of benthic rotaliid fauna at the phosphate oil shale member transition mark the most prominent change in the upwelling sequence this change probably reflects moderate weakening of the eutrophic surface water productivity and a regional sea level rise resulting in seafloor deepening and improved seafloor aeration a further step in the decrease in toc content to 5 5 8 wt occurs in the uppermost part of the osm latest campanian and corresponds to the transitions to assemblages p type 1 and b type 1 this change suggests a shift to mesotrophic conditions additional increase in bottom and pore water aeration and thus the demise of the upwelling activity in the southern tethys

fault and fracture control of fluid and diagenesis around the iberia salt dome iberia parish louisiana abstract recognition of the pathways that channel kilometer scale vertical fluid movements around salt domes is important to the understanding of petroleum migration and injection well disposal it is hypothesized that the vertical component of flow is accommodated by fractures faults porosity developed in the margin of the salt and through complexly interconnected sands by means of geochemical and petrographic techniques specific fluid migration pathways have been identified on the southwest flank of the iberia salt dome iberia parish louisiana brine samples from the iberia oil field have been analyzed by icp aes for dissolved na k mg ca sr ba mn fe cu pb zn al si and b the concentration data were contoured on a cross section developed from well logs to identify spatial correspondence between structures or sand bodies and compositional gradients of solutes within the pore fluids contour lines for ba b ca fe and sr deflect from sub parallel with formation dip to sub parallel with high angle faults this suggests that the faults either directly accommodate vertical fluid movement or serve to juxtapose permeable sands in sand mudstone successions thus forming vertical pathways of complexly interconnected sands sem eds inspection of well cuttings reveals the presence of diagenetic calcite pyrite vermiform kaolinite barite and sphalerite in pore spaces in some samples mineralization in dilated micro fractures reveals that fracture porosity also contributes to pore fluid movement in the iberia flank sediments thus faults and fractures contribute to vertical fluid flow and solute transport over a wide range of dimensional scales at the iberia salt dome

organic geochemistry of duckmantian pennsylvanian coals from the ruhr basin western germany abstract the molecular composition of 58 duckmantian ruhr coals and adjacent sedimentary rocks has been analyzed using organic geochemical investigations representing a maturity range from 0 74 to 0 98 vitrinite reflectance in addition eight samples of higher maturity 1 46 to 3 55 vitrinite reflectance were studied for comparison the composition of coals depends primarily on plant input into the peat swamps but also to a large extent on thermal maturity several maturity related parameters have been applied in this study such as mpi dmai and diverse hopanoid based maturity ratios especially diamantane based parameters proved to be excellent for characterizing high rank samples whereas hopane and phenanthrene based parameters are well suited for the lower maturity range various specific biomarkers reflect the composition of the duckmantian coals concerning the floral differences and floral shift during the westphalian the dominating n alkanes hopanes and bicyclic sesquiterpanes show only marginal differences and reveal a quite homogenous floral composition within the six coal seams tetracyclic diterpanes as approved markers for modern as well as paleozoic conifers and pre gymnosperms have been identified in all six coal seams but in low concentration one order of magnitude lower than bicyclic sesquiterpanes a slight increase of the tetracyclic diterpane ent beyerane in the younger seams indicates an increase in abundance of pre gymnosperms cordaites during the duckmantian significantly increased proportions of diverse compounds like bicyclic sesquiterpanes eudesmane or tetracyclic terpanes clearly testify an origin from higher land plants the major part of the duckmantian coal swamps biomass with its vitrinite rich coals originated presumably from barks of arborescent lycopods high concentrations of hopanes mirror the input of bacterial organic matter and a strong microbial reworking of the deposited terrestrial plant organic matter

petroleum source rocks of the tarfaya basin and adjacent areas morocco abstract this work characterizes the source rock potential of the tarfaya basin and enabled us to reconstruct its geochemical history outcrop samples covering different stratigraphic intervals plus the northwestern part of the zag tindouf basin bas draa area were analyzed for total organic carbon corg and total inorganic carbon contents and total sulfur content rock eval analysis and vitrinite reflectance measurements were performed on 56 samples chosen on the basis corg content a set of 45 samples were extracted and non aromatic hydrocarbons were analyzed by way of gas chromatography flame ionization detection gc fid and gc mass spectrometry gc ms non isothermal open system pyrolysis at different heating rates was applied to obtain kinetic parameters for modelling petroleum generation from four different source rocks high quality petroleum source rocks with high corg content and hydrogen index hi values were found for samples of eocene coniacian turonian and cenomanian age most samples were carbonate rich and organic sulfur values were high to moderate various maturity parameters indicated immature or possibly early mature organic matter based on organic geochemical and petrological data the organic matter is of marine aquatic origin cenomanian or a mixture of aquatic and terrigenous material eocene the early cretaceous interval did not contain high quality source rocks but indications of petroleum impregnation were found

atmospheric circulation upwelling and organic rich rocks in the mesozoic and cenozoic eras abstract by using the basic principles of atmospheric circulation and analogies from present circulation patterns it is possible to construct qualitative atmospheric circulation models on paleogeographic maps the wind patterns predicted by these models then serve as the basis for predicting the locations of ancient upwelling zones atmospheric circulation and upwelling models for seven geologic stages in the mesozoic and cenozoic were constructed and the distribution of the upwelling zones compared with the distribution of organic rich rocks for all time periods together the correlation was statistically significant when the individual time periods were analyzed separately the following pattern emerged significant correspondence between upwelling zones and organic rich rocks in the triassic middle early cretaceous to late cretaceous and middle paleogene to neogene no significant correspondence was found for the intervening times upwelling does not account for all organic rich rocks so called anoxic oceanic events and transgressions play an important role in their deposition it is suggested that upwelling contributes significantly to the pattern of organic rich rock distribution and is important in determining organic facies

geochemical and petrographic characterization of campanian lower maastrichtian calcareous petroleum source rocks of hasbayya south lebanon abstract santonian paleocene marls and fine grained carbonates have been sampled in hasbayya locality south lebanon in order to evaluate their organic matter om content petroleum source rock potential and assess their depositional environment methods included total organic carbon toc total inorganic carbon tic total sulphur ts rock eval pyrolysis organic and inorganic petrography x ray fluorescence xrf gas chromatography mass spectrometry gc ms and curie point pyrolysis gas chromatography mass spectrometry cp py gc ms toc rock eval and vitrinite reflectance vrr results reveal excellent immature petroleum source rocks within the campanian lower maastrichtian interval with toc up to 11 6 wt hydrogen index hi up to 872 mg gtoc tmax up to 433 c and vrr average of 0 36 biomarker ratios and maceral analysis suggest a marine depositional environment with a dominance of algal as well as submicroscopic om original sediment composition and redox sensitive geochemical parameters suggest deposition of the om rich intervals under an oxygen minimum zone omz that was emplaced and controlled by primary productivity and nutrient supply pyrolysate composition shows an important content of organic sulphur compounds thiophenes increasing with toc and thus indicating the presence of type ii and type iis kerogen in the analysed sample set which is consistent with the presence of immature solid bitumen in the hasbayya region the data produced in this study coupled with regional correlations allow us to construct a conceptual depositional model for the upper cretaceous om rich rocks of the eastern mediterranean suggesting deposition under a productivity belt localized along the inner and outer shelf leading to a decrease in source rock quality and a shift in kerogen type toward the deeper parts of the levant basin

ostracode mg ca paleothermometry in the north atlantic and arctic oceans evaluation of a carbonate ion effect 1 the reconstruction of deep sea bottom water temperature bwt is important to assess the ocean s response to and role in orbital and millennial scale climate change deep sea paleothermometry employs magnesium to calcium mg ca ratios in calcitic benthic microfaunas foraminifera ostracodes as a primary proxy method mg ca paleothermometry may however be complicated by bottom water carbonate ion chemistry which might affect mg ca ratios in shells to address temperature and carbonate ion influence on mg ca ratios we studied mg ca ratios in the benthic ostracode genus krithe in the north atlantic and arctic oceans using a 686 specimen core top collection including 412 previously unpublished analyses mg ca ratios are positively correlated to temperature in multiple species from the north atlantic bwt 0 885 mg ca 5 69 r2 0 73 and for k glacialis in the arctic ocean and nordic seas bwt 0 439 mg ca 5 14 r2 0 50 consistent with previously published calibrations we found no evidence for a relationship between krithe mg ca and carbonate ion saturation in the north atlantic ocean nordic seas and arctic ocean supporting the use of krithe mg ca for reconstructing past bwt

carbon and sulfur relationships in marine senonian organic rich iron poor sediments from israel a case study abstract in fe poor and organic rich marine sediments reduced s is mainly organic due to the lack of reactive fe these sediments e g carbonates cherts phosphates have high c s organic carbon total reduced sulfur ratios which are as a rule 3 and may reach 5 or 6 at times even 10 in organic rich rocks these high ratios are characteristic for these fe barren sediments and are very different from those found in marine sediments where pyritic s is the main reduced sulfur species they may be explained by the escape of h 2 s to the atmosphere the interpretation of c 1bs plots in these sediments is also quite different one reason for the s intercept in these plots is the presence of pyritic s and thus contrary to the conventional plots this intercept seems to have no environmental significance on the other hand the s c slope appears to be a paleoenvironmental indicator low slopes 0 2 indicate restricted to normal aerobic environments c 1bs plots have been used to interpret environments of deposition in such sediments from two cycles of organic rich fe poor senonian sediments in several basins in central and southern israel both cycles appear to have been deposited in restricted environments the campanian mishash formation environments of deposition appear to be in general more oxic than those of the maastrichtian ghareb formation as an independent comparison for the c s results the degree of pyritization dop was calculated for some samples the dop results confirmed the c s results it should be stressed that in such low fe environments even dop results should be used with caution

calcium isotope fractionation during coccolith formation in emiliania huxleyi independence of growth and calcification rate 1 recently calcium isotope fractionation in the coccolithophore emiliania huxleyi was shown to exhibit a significant temperature dependency an important subsequent question in this context is whether the observed fractionation patterns are caused by temperature itself or related growth rate changes in order to separate growth and calcification rate effects from direct temperature effects batch culture experiments with the coccolithophore e huxleyi were conducted under varying light intensities despite large changes in cellular growth and calcification rates calcium isotope fractionation remained constant independence of calcium isotope fractionation on growth and calcification was also obtained in two additional sets of experiments in which growth rates changed in response to varying calcium concentration and seawater salinity these experiments also showed no direct effects of calcium concentration and salinity on calcium isotope fractionation values for calcium isotope fractionation of e huxleyi coccoliths fell within a range of 1 0 to 1 6 1000 ln confirming earlier results this range is similar to that observed in several foraminiferal species and coccolith oozes suggesting a rather homogeneous calcium isotopic composition in marine biogenic calcite our data further show that the calcium isotope fractionation does not change with changing isotopic composition of seawater this is a basic requirement for reconstructing the calcium isotopic composition of the ocean over time

geochemical and petrographic investigation of triassic and late miocene organic rich intervals from onshore cyprus eastern mediterranean abstract in order to improve the understanding of potential petroleum systems in the still underexplored eastern mediterranean sea two field campaigns were performed to investigate potential source rocks onshore cyprus elemental data total organic toc and inorganic carbon tic total sulfur ts fe ni v rock eval pyrolysis biomarker and microscopic analysis organic petrography random vitrinite reflectance vrr palynofacies of the obtained mesozoic to cenozoic samples have proven the existence of organic matter om rich deposits within the following two geological formations 1 the triassic vlambouros formation fm of the mamonia complex comprises frequently occurring few centimeter thin clay layers interbedded between meter thick sandstone units the clay layers of this formation are characterized by toc contents of about 1 wt representing a type iii kerogen showing hydrogen index hi values of 48 mg hc g toc on average vrr values of 0 5 to 0 6 as well as several biomarker ratios indicate low thermal maturity the formation was deposited at the northern margin of gondwana and similar strata may be present in the basement of the levant basin and the eratosthenes seamount there thermal maturity would be higher and such rocks might contribute to thermogenic gas systems 2 in the miocene pakhna fm om bearing intervals are mainly present in the upper part of the formation in outcrops east of the troodos mountain while organic rich intervals are very scarce to absent in the south and southwest of the island the eastern outcrops show abundant fine grained marly mud to wackestones interbedded with coarser grained carbonates the fine grained intervals have toc contents of about 4 wt representing mainly type ii iii kerogen with hi values of 238 mg hc g toc on average the om is immature as indicated by vrr values between 0 3 and 0 5 ts toc 2 8 and several biomarker ratios indicate oxygen depleted even anoxic conditions during deposition a negative correlation between the toc and tic indicates that such conditions were reached during enhanced primary bioproductivity controlled by local and regional clastic derived nutrient input similar conditions may have been present along the southeastern margin of the eratosthenes seamount south of cyprus presence of abundant organic matter and high sedimentation rates during the miocene were favorable for microbial gas generation in the deeper parts of the basins

coupled δ44 40ca δ88 86sr and 87sr 86sr geochemistry across the end permian mass extinction event abstract we report high resolution high precision 44 40ca 88 86sr and 87sr 86sr records spanning the permian triassic boundary ptb from the meishan and dajiang carbonate successions in south china the goal of the study was to understand the behavior of ca and sr isotopes during a time period in earth history characterized by severe biological and environmental perturbations including a major mass extinction flood basalt volcanism ocean acidification and sea level fluctuations dajiang displays negative 44 40ca and 88 86sr excursions and invariant 87sr 86sr ratios in the

calcium isotope fractionation in coccoliths of cultured calcidiscus leptoporus helicosphaera carteri syracosphaera pulchra and umbilicosphaera foliosa four species of marine calcifying algae the coccolithophores calcidiscus leptoporus helicosphaera carteri syracosphaera pulchra and umbilicosphaera foliosa were grown in laboratory cultures under temperatures varying between 14 and 23 c and one species c leptoporus under varying co32 ranging from 105 to 219 mol kg calcium isotope compositions of the coccoliths resemble in both absolute fractionation and temperature sensitivity previous calibrations of marine calcifying species e g emiliania huxleyi coccolithophores and orbulina universa planktonic foraminifera as well as inorganically precipitated caco3 but also reveal small species specific differences in contrast to inorganically precipitated calcite but similar to e huxleyi and o universa the carbonate ion concentration of the medium has no statistically significant influence on the ca isotope fractionation of c leptoporus coccoliths however combined data of e huxleyi and c leptoporus indicate that the observed trends might be related to changes of the calcite saturation state of the medium since coccoliths constitute a significant portion of the global oceanic caco3 export production the ca isotope fractionation in these biogenic structures is important for defining the isotopic composition of the ca sink of the ocean one of the key parameters for modelling changes to the marine ca budget over time for the present ocean our results are in general agreement with the previously postulated and applied mean value of the oceanic ca sink sed of about 1 3 but the observed inter and intra species differences point to possible changes in sed through earth history due to changing physico chemical conditions of the ocean and shifts in floral and faunal assemblages

predicting the generation of heavy oils in carbonate evaporitic environments using pyrolysis methods abstract a series of low maturity kerogen and asphaltene samples of a sulphur rich mediterranean carbonate source rock sequence as well as two associated oil samples were analysed by different pyrolysis methods the source rock was characterised by the occurrence of four different lithotypes three of which possessed source potential elemental analysis revealed that each source lithofacies contained a distinct kerogen type comprising type i s for shale intercalations type ii s in the laminated lithofacies and low sulphur type ii in the pure carbonate portions of the source rock pyrolysis gas chromatography using coupled fid and hecd detectors provided a more detailed insight into kerogen asphaltene composition than afforded by rock eval pyrolysis bulk kinetic analysis demonstrated that asphaltenes and type i s kerogens were the most labile species present in the source rocks type ii s kerogens often quoted as the major source of heavy oils were the most stable of the sulphur rich organic matter types the occurrence of various kerogen types with differing stabilities in the carbonate source rock analysed as determined by bulk pyrolysis fid implies that peak hydrocarbon generation in the source rock sequence is not confined to a single temperature but rather to a relatively large temperature range of roughly 20 c combination of bulk hydrocarbon generation kinetics and a multistep pyrolysis approach demonstrated that for carbonate evaporitic environments it is necessary to differentiate between early and late maturity products this is because the lower energies 46 49 kcal mol which may be attributed to s c bond cleavage reactions are empirically of greater importance especially in view of the fact that they may represent the main generation stage under natural conditions

genetic classification of petroleum systems our genetic classification of petroleum systems is founded on a simple working nomenclature that consists of combining qualifiers from each of the following three categories 1 charge factor supercharged normally charged or undercharged 2 migration drainage style vertically drained or laterally drained and 3 entrapment style high impedance or low impedance the charge factor is estimated on the basis of the richness and volumetrics of mature source rocks the source potential index spi which combines source rock richness and thickness into a single parameter is a convenient shortcut for comparing the petroleum potential of diverse source rocks containing dissimilar kerogen types and for rapidly estimating regional charging capacity in extensively explored basins a positive correlation exists between the magnitude of spi and basin wide petroleum reserves the migration drainage style is determined from the structural and stratigraphic framework of a basin vertical migration drainage which occurs mainly through faults and fracture systems breaching a seal is characteristic of petroleum systems contained within rift basins deltaic sequences salt dome provinces wrench basins and fold and thrust belts in contrast lateral migration drainage is dominant wherever stratigraphically continuous seal reservoir doublets extend over a very large area in a tectonically stable province e g commonly foreland or intracratonic platform basins recognition of the dominant migration style helps to predict the location of zones of petroleum occurrence in relation to the hydrocarbon kitchens the entrapment style which is also dependent on the structural framework and the presence and effectiveness of seals describes the degree of resistance i e impedance working against dispersion of the petroleum charge application of these working concepts should help to significantly reduce geologic risk particularly in new ventures type exploration

dolomite calcitization and cement zonation related to uplift of the raisby formation zechstein carbonate northeast england abstract the raisby formation is the basal zechstein carbonate of northeast england it has undergone a complex diagenetic history during burial including multiphase dolomitization and replacement by sulphates upon uplift meteoric derived fluids have dissolved this replacive sulphate and precipitated calcite cements in the resultant porosity study of these cements by cathodoluminescence and trace element geochemistry shows that they are zoned and different cathodoluminescence zones correlate well with iron and manganese geochemical changes demonstrating a gradual increase in oxygenation of the precipitating fluids through time major diagenetic processes during cement growth include precipitation of anhydrite fluorite and barite calcitization of dolomite and internal sedimentation relating these processes to cement zonation allows this complex diagenesis to be explained in terms of uplift under the influence of meteoric derived groundwaters of constantly changing geochemical and electrochemical characteristics

quantification of loss of calcite pyrite and organic matter due to weathering of toarcian black shales and effects on kerogen and bitumen characteristics abstract comparison of geochemical data on posidonia shale early toarcian from a shallow unweathered core and from adjacent weathered exposures of the same fades was performed results revealed that quantitatively the most affected petrographic constituent is pyrite and that organic matter and carbonate were also altered by weathering due to this process of weathering the bulk composition of organic matter especially the molecular composition of soluble organic matter and the fluorescence colour of organic particles are changed estimates of weathering rates reveal that the annual release of sulphur and organic carbon from black shales may significantly add to anthropogenic pollution

tectono stratigraphic evolution of the northern levant basin offshore lebanon abstract seismic interpretation constrained by a detailed assessment of the levant paleogeography allowed subdividing the sedimentary infill of the northern levant basin offshore lebanon in eight major seismic packages fifteen seismic facies have been identified with distinctive characteristics the levant basin architecture is pre determined by a late paleozoic early mesozoic rift that led to the formation of a passive margin dominant aggrading carbonate platforms are observed along the levant margin and deepwater mixed settings i e carbonates and siliciclastics are suggested to prevail in the basin the collision of afro arabia with eurasia led to the development of a flexural basin in the northernmost offshore lebanon since the late cretaceous a southward migration of this flexural depocenter in the miocene is hindered by the change in the stress field along the latakia ridge and by the westward escape of the anatolian plate in late miocene and pliocene times interplay between major geodynamic events as well as sea level fluctuations in the mesozoic and cenozoic induced important marginal uplifts and emersion sediments sourced from the erosion of nubian siliciclastic material and from the exposed granitic red sea rift shoulders and arabian shield were driven into the levant basin the sediment sources diversity the mechanisms of sediment transport through varied pathways i e the levant margin canyons the latakia region and the nile delta deep sea cone are expected to strongly impact the reservoir characteristics and prospectivity of the northern levant basin

calcium isotopes in deep time potential and limitations abstract calcium is an essential element in the biogeochemical cycles that regulate the long term climate state of earth the removal of co2 from the ocean atmosphere system is controlled by the burial of carbonate sediments caco3 ultimately linking the global calcium and carbon cycles this fundamental link has driven the development of the stable calcium isotope proxy with application to both ancient skeletal and non skeletal bulk carbonate sediments calcium isotope ratios 44 40ca have been used to track long term changes in seawater chemistry e g aragonite vs calcite seas and to elucidate short term climatic perturbations associated with mass extinction events however developments in the calcium isotope proxy have shown that 44 40ca values in carbonate minerals also are sensitive to changes in precipitation rates mineralogy and diagenesis thereby complicating the application of the proxy to the reconstruction of global cycles first inorganic carbonate precipitation experiments have demonstrated that carbonate 44 40ca values are sensitive to precipitation rates with higher rates generally leading to larger fractionation second 44 40ca values are sensitive to carbonate mineralogy with inorganic aragonite and calcite being on average 1 5 and 0 9 depleted relative to contemporaneous seawater respectively the effects of both changes in carbonate mineralogy and precipitation rates affect primary and secondary minerals but are particularly pronounced during carbonate diagenesis where relatively slow rates of recrystallization and neomorphism can lead to significant changes in bulk sediment 44 40ca values third changes in faunal composition expressed in skeletal fossil archives can lead to large changes in carbonate 44 40ca values that are decoupled from changes in global cycles nevertheless when these factors are appropriately considered the application of calcium isotopes in ancient carbonate sediments becomes a powerful tool for understanding biogeochemical processes that operate over many scales from diagenetic changes within the sediment pore space to regional changes across ancient carbonate platforms and to global changes in seawater chemistry through time importantly the processes that contribute to variability in carbonate 44 40ca values are likely to impact other carbonate bound proxies highlighting the potential for calcium isotopes as a tool to better understand the variability of other isotope systems

cellular calcium pathways and isotope fractionation in emiliania huxleyi the marine calcifying algae emiliania huxleyi coccolithophores was grown in laboratory cultures under varying conditions with respect to the environmental parameters of temperature and carbonate ion concentration co32 concentration the ca isotope composition of e huxleyi s coccoliths reveals new insights into fractionation processes during biomineralization the temperature dependent ca isotope fractionation resembles previous calibrations of inorganic and biogenic calcite and aragonite unlike inorganically precipitated calcite the co32 concentration of the medium has no significant effect on the ca isotope composition of the coccoliths these results indicate a decoupling of the chemical properties of the bulk medium and the calcifying vesicle cellular ca pathways of e huxleyi indicate that fractionation cannot occur at the crystal surface as occurs during inorganic precipitation the dominant processes leading to the observed ca isotope fractionation pattern in e huxleyi are most likely the dehydration of the ca aquocomplex at the plasma membrane and the attachment of dissolved ca to proteins of ca channels the independence of ca isotope fractionation from co32 and the small temperature dependence of e huxleyi are also important for defining the isotopic signature of the oceanic ca sink since coccolithophores contribute to about half the global caco3 production a relatively uniform isotopic composition of the oceanic ca sink is further supported

a global evaluation of temperature and carbonate ion control on mg ca ratios of ostracoda genus krithe 1 improving estimates of past ocean temperatures is paramount to our understanding of ocean circulation and its role in climate change magnesium calcium mg ca ratios of carapaces of the benthic ostracod genus krithe were determined from new globally distributed core top samples from the norwegian sea cape hatteras shelf gulf of mexico sulawesi margin indonesia new zealand shelf ceara rise and the north atlantic a linear regression of the krithe mg ca ratios and bottom water temperature bwt reveals a significant correlation for locations where temperature during carapace calcification was above 3 c which can be described by the equation mg ca 0 972 0 152 bwt 7 948 1 103 consistent with previous north atlantic calibrations deviations from the global calibration line below 3 c follow the same pattern observed for benthic foraminifera suggesting that the incorporation of magnesium into ostracodal calcite may be secondarily controlled by changes in carbonate ion concentration therefore we propose a linear regression that describes the relationship between magnesium incorporation temperature and carbonate saturation for low temperatures 3 c mg ca 0 972 0 152 bwt 0 100 0 030 d co3 4 440 1 103 1 se 0 3 c while the standard error of the calibration is small it requires an accurate knowledge of past d co3 concentration which necessitates additional proxy data applying the calibration to glacial samples from the deep north atlantic ocean we show that estimates of bottom water temperatures generated from the new d co3 corrected equations are more consistent with results from oxygen isotopes and pore water studies

influences on the fractionation of calcium isotopes in planktonic foraminifera for paleoceanographic studies it is important to understand the processes that influence the calcium ca isotopic composition of foraminiferal calcite tests preserved in the sediment record seven species of planktonic foraminifera from coretop sediments collectively exhibited a ca temperature dependent fractionation of 0 013 per c thisisin agreement with previously published estimatesformostspecies ofplanktonic foraminifera as well asbiogenicandinorganiccalciteandaragonite fourspeciesofplanktonicforaminiferacollectedfromasedimenttrapshowedaconsiderableamountof scatterandnoconsistenttemperaturedependentfractionation analyzedsizefractionsofcoretopsamplesshownosignificantrelationshipwith 44 40 ca however preliminary results suggest that the symbiotic and spinose foraminifera globigerinoides sacculifer might exhibit a relationship between test size and 44 40 ca a one box model in which ca isotopes are allowed to fractionate by rayleigh distillation from a biomineralization reservoir internal pool was used to constrain the isotopic composition of the original biomineralization ca reservoir assuming around 85 of the ca reservoir is precipitatedandthefractionationfactorduringprecipitationis0 9985 0 00002 t c toexplaintheforaminiferalcaisotopedata thismodelindicates

some outstanding issues in the geology of lebanon and their importance in the tectonic evolution of the levantine region abstract the concept of pervasive and disruptive late neogene quaternary strike slip tectonics in lebanon has made establishing a satisfactory pre neogene palaeogeographic and palaeotectonic history for the area difficult research has allowed clarification of three fundamental issues that permit the setting of lebanon against its adjacent regions to be more firmly assigned the first issue is the identification of the significance of the 100 km long nne ssw trending monocline of the western lebanon flexure this feature is interpreted as a modified and rejuvenated early mesozoic hinge line that is presumed to be the northern continuation of the carmel sinai hinge line to the south the second issue is the correlation of the mount lebanon bekaa and anti lebanon complex with the adjacent intracontinental palmyride fold belt of syria through recognition in each of common divisions in structural style between a higher northern zone dominated by broadly spaced box folds and a lower southern zone with more numerous closely spaced and more internally complex folds the third issue involves the identification of major two stage late cretaceous to palaeogene syrian arc tectonism within lebanon resolution of these issues suggests a tectonic model for the region whereby the levantine region formed in two main phases the first of these was the multiphase late palaeozoic early mesozoic rifting of the area which imposed a fundamental extensional fabric over much of the region the second tectonic phase was the subsequent inversion of these extensional structures in the two stage syrian arc deformation of senonian and late palaeogene age which gave rise to the main lebanon structures it is this syrian arc tectonism rather than the late cenozoic strike slip that was probably the main structuring agent which affected the lebanon area the transpression from the braided dead sea fault motion although locally complex is an essentially neotectonic overprint on an already existing fabric offset of syrian arc structures in lebanon suggests that the total sinistral motion of the yammouneh fault segment of the dead sea fault is around 47 km

source rock characteristics and hydrocarbon expulsion potential of the middle eocene wenchang formation in the huizhou depression pearl river mouth basin south china sea abstract the middle eocene wenchang wc formation in the huizhou depression of the pearl river mouth basin is an important geological element for petroleum exploration in the south china sea in this study the geological and geochemical characteristics of the wc source rocks including the distribution sedimentary environment organic matter type hydrocarbon generation potential and thermal maturity were investigated hydrocarbon generation history and hydrocarbon expulsion intensity and quantities were evaluated through one dimensional basin modelling and an improved hydrocarbon generation potential methodology the wc source rocks are widely distributed and have an elevated thickness mostly thicker than 200 m with a maximum thickness greater than 1000 m they were deposited in a lacustrine weak oxidation weak reduction sedimentary environment with low salinity the source rocks have low to high organic matter abundance toc mainly ranges from 0 27 to 3 59 wt with an average of 1 39 wt dominated by ii 1 type and ii 2 type kerogen resulting in significant hydrocarbon generating potential under moderate high thermal evolution r o mainly ranges from 0 65 to 1 2 on the margins of sags and greater than 1 2 in the centre of sags the source rocks became mature r o 0 5 in the early miocene and began to generate hydrocarbons they reached the hydrocarbon expulsion threshold at 0 8 r o and the hydrocarbon expulsion rate became greatest at 1 1 r o the expulsion intensities in the h26 sag h21 sag x24 sag and x23 sag are relatively large with their greatest expulsion intensities being 104 10 6 71 10 6 62 10 6 and 53 10 6 t km 2 respectively the comprehensive hydrocarbon expulsion efficiency was approximately 75 about 690 1 10 8 t of hydrocarbons were expulsed from the wc source rocks in the huizhou depression

geochemical characteristics of carbonaceous chalk near the cretaceous paleogene transition central jordan strong metal enrichment of redox sensitive and biophile elements from remineralized calcitic plankton abstract carbonaceous calcitic chalk from a 50 m stratigraphic sample interval n 35 of the maastrichtian danian muwaqqar chalk marl mcm formation jordan has elevated concentrations of biophile and or redox sensitive trace metals mo ni v u cr cd ag se and p which indicate enhanced paleo bioproductivity biodegradation and remineralization under reducing conditions very low concentrations in mn and ba suggest a relatively open system for components mobile under reducing conditions the last 800 000 years to the k pg boundary are not exposed in jordan but the stratigraphic 20 m interval below and above the hiatus of the k pg transition n 8 with 2 6 1 8 wt organic c is particularly metal enriched with average bulk rock contents of 132 ppm mo 177 ppm ni 363 ppm v 576 ppm zn 39 ppm se 1 4 ppm ag 106 ppm cd 474 ppm cr these concentrations are dominantly of authigenous origin when normalized to paas i e 100 mo 100 ag 100 cd 96 cr 95 ni 95 zn 80 v authigenous and testify to 90 of biodegradation of planktonic debris by anaerobic bacterial activity at or near the seafloor the depositional environment is euxinic and mo toc ratios from

reflux stratabound dolostone and hydrothermal volcanism associated dolostone a two stage dolomitization model jurassic lebanon the kesrouane formation which is characterized by pervasive dolomitization has a stratigraphic thickness that exceeds 1000 m it is part of a broad carbonate platform deposited in the levant region and represents 60 of the lebanese jurassic rocks two genetically distinct dolostones are recognized within this unit 1 fine to medium crystalline non planar grey dolostone and 2 coarse crystalline planar beige dolostone the former is stratabound and of early jurassic age 87 sr 86 sr 0ae707455 this dolostone locally exhibits pseudomorphs of evaporite nodules pointing towards seepage reflux dolomitization by hypersaline to marine related fluids exposures of the coarse crystalline dolostone are associated with regional pre cretaceous faults along which late jurassic volcanics also occur sedimentological and diagenetic considerations coupled with microthermometry support a hydrothermal origin for this dolostone with th values of primary inclusions between 50 and 80 c the related dolomitizing fluids are mesosaline 3ae5 12ae0 eq wt nacl and are believed to result from the mixing of evaporative brines and sea water dolomitization is thus believed to have occurred in two stages whereby fluids invaded the host rocks first by seepage reflux explaining the resulting early jurassic stratabound dolostone and later through fracture flow along the faults associated with the late jurassic volcanism explaining the coarse crystalline hydrothemal dolostone

late cretaceous late turonian coniacian and santonian petroleum source rocks as part of an oae tarfaya basin morocco abstract late turonian coniacian and santonian source rock samples from a recently drilled well tafaya sondage no 2 2010 in the tarfaya basin were analyzed for quantity quality maturity and depositional environment of the organic matter om to our knowledge such a thick sequence of organic matter rich turonian to santonian source rocks was investigated in that great detail for the first time organic geochemical and organic petrological investigations were carried out on a large sample set from the 200 m thick sequence in total 195 core samples were analyzed for total organic carbon corg total inorganic carbon contents and total sulfur ts contents rock eval pyrolysis and vitrinite reflectance measurements were performed on 28 samples chosen on the basis of their corg content non aromatic hydrocarbons were analyzed on selected samples by way of gas chromatography flame ionization detection gc fid and gc mass spectrometry gc ms the organic matter rich carbonates revealed a high source rock potential representing type i kerogen and a good preservation of the organic matter which is mainly of marine phytoplankton origin hi values are high 400 900 mg g corg and in a similar range as those described for more recent upwelling sediments along the continental slope of north africa ts corg ratios as well as pristane over phytane ratios indicate variable oxygen content during sediment deposition all samples are clearly immature with respect to petroleum generation which is supported by maturity parameters such as vitrinite reflectance 0 3 0 4 tmax values 401 423 c production indices s1 s1 s2 0 1 as well as maturity parameters based on ratios of specific steranes and hopanes

oxygen minimum zones omzs in the modern ocean in the modern ocean oxygen minimum zones omzs are potential traces of a primitive ocean in which archean bacteria lived and reduced chemical anomalies occurred but omzs are also keys to understanding the present unbalanced nitrogen cycle and the oceans role on atmospheric greenhouse control omzs are the main areas of nitrogen loss as n2 n2o to the atmosphere through denitrification and anammox and could even indirectly mitigate the oceanic biological sequestration of co2 it was recently hypothesized that omzs are going to spread in the coming decades as a consequence of global climate change despite an important omz role for the origin of marine life and for the biogeochemical cycles of carbon and nitrogen there are some key questions on the structure of omzs at a global scale there is no agreement concerning the threshold in oxygen that defines an omz and the extent of an omz is often evaluated by denitrification criteria which at the same time are o2 dependent our work deals with the identification of each omz the evaluation of its extent volume and vertical structure the determination of its seasonality or permanence and the comparison between omzs and denitrification zones at a global scale the co existence in the omz of oxic in its boundaries and suboxic even anoxic in its core conditions involves rather complex biogeochemical processes such as strong remineralization of the organic matter removal of nitrate and release of nitrite the quantitative omz analysis is focused on taking into account the whole water volume under the influence of an omz and adapted to the study of the specific low oxygen biogeochemical processes a characterization of the entire structure for the main and most intense omzs o2 10 mu m maximum zone the larger omz relative to the extent of denitrification zone suggests that the unbalanced nitrogen cycle on the global scale could be more intense than previously recognized and that evaluation of the omz from denitrification could underestimate their extent

anoxia vs productivity what controls the formation of organic carbon rich sediments and sedimentary rocks discussion the prevailing explanation for the origin of organic rich sediments and rocks invokes deposition under conditions of anoxia however recent research suggests that high primary production and not water column anoxia provides the first order control on the accumulation of organic rich facies in the modern oceans oxygen minima do not appear to have any direct effect on carbon accumulation in continental margin or marginal sea environments sediments accumulating in the modern black sea the type euxinic basin are not particularly enriched in organic matter despite the presence of an anoxic water column although a sapropel containing extremely high carbon concentrations was deposited during the holocene at a time when the basin was oxic results of a recently published co pled ocean atmosphere model indicate that during the cretaceous thermohaline and surface circulation in the oceans was similar to or more intense than modern conditions despite the overall equable climate such conditions confound the idea that circulation in the cretaceous atlantic for example was punctuated by oceanic anoxic events brought about by more sluggish circulation sporadic temporal and spatial increases in primary production reflecting changes in the behavior and or state of the ocean atmosphere system constitute a more tenable explanation for the occurrence of modern and quaternary carbon rich sediments and cretaceous black shales consequently the fundamental control on the accumulation of carbon rich facies in the oceans and marginal seas is not the presence or absence of anoxia

minor element and ca isotope composition of calcareous dinoflagellate cysts of cultured thoracosphaera heimii abstract we investigated the influences of temperature salinity and ph on the calcium isotope as well as trace and minor element uranium strontium magnesium to ca ratios on calcium carbonate cysts of the calcareous dinoflagellate species thoracosphaera heimii grown in laboratory cultures the natural habitat of this species is the photic zone preferentially at the chlorophyll maximum depth of temperate to tropical oceans and it is abundant in deep sea sediments over the entire cenozoic in our experiments temperatures ranged from 12 to 30 c salinity from 36 5 to 38 8 and ph from 7 9 to 8 4 the 44 40ca of t heimii cysts resembles that of other marine calcifiers including coccolithophores foraminifers and corals however its temperature sensitivity is considerably smaller and statistically insignificant and t heimii might serve as a recorder of changes in seawater 44 40ca over geologic time the sr ca ratios of t heimii cysts show a pronounced temperature sensitivity 0 016 mmol mol c 1 and have the potential to serve as a palaeo sea surface temperature proxy no clear temperature and ph dependences were observed for mg ca u ca seems to be influenced by temperature and ph but the correlations change sign at 23 c and ph 8 2 respectively

modern and palaeo oceanographic environments under benguela upwelling cells off southern namibia averaged benthic physical and chemical and key microfaunal ostracoda parameters of the bottom waters and substrate allow a ranking of the intensity of upwelling in the modern cells off southwestern africa b1 b6 b1 namib cell temperature salinity dissolved oxygen total organic matter 10 3 c 34 94 1 2 ml l 6 2 palmoconcha walvisbaiensis cytherella namibensis garciaella knysnaensis robusta and neocaudites lordi b2 walvis cell 11 0 c 35 00 1 0 ml l 9 2 palmoconcha walvisbaiensis cytherella namibensis garciaella knysnaensis robusta buntonia rogersi neocaudites lordi and ruggieria cytheropteroides leeward side only b3 luderitz cell 9 1 c 34 77 1 8 ml l 6 3 palmoconcha walvisbaiensis cytherella namibensis incongruellina venusta kuiperiana angulata and ruggieria cytheropteroides leeward side only b4 namaqua cell 10 0 c 34 82 2 4 ml l 3 1 pseudokeijella lepralioides and ruggieria cytheropteroides b5 columbine cell 8 3 c 34 70 3 1 ml l 3 9 ruggieria cytheropteroides pseudokeijella lepralioides poseidonamicus panopsus and ambostracon a flabellicostata b6 peninsula cell 8 9 c 34 63 3 6 ml l 1 9 pseudokeijella lepralioides ambostracon a keeleri cytherella dromedaria neocytherideis boomeri xestoleberis africana neocaudites osseus coquimba birchi and urocythereis arcana pleistocene palaeo upwelling characteristics of the shelf north west of luderitz are investigated by analysing the ostracod faunas sediment textures and mineralogy of three large volume gravity cores q mode factor analyses using previously published transfer functions allow predictions for benthic environmental parameters during the late pleistocene the area experienced less intense upwelling and lower primary productivity than at present in an environment equated with a modified peninsula cell b6 b7 cell 9 6 c 34 73 3 2 ml l 3 9 neocaudites lordi ambostracon a keeleri bairdoppilata simplex paracypris lacrimata parakrithella simpsoni xestoleberis hartmanni ruggieria cytheropteroides and pseudokeijella lepralioides in middle and early pleistocene late pliocene times the core sites lay closer inshore adjacent to evaporite halite and authigenic phosphorite rich lagoons with a high intensity upwelling walvis like cell b1 to the north west and a low intensity upwelling cell b7 to the south

macrobenthic community structure in a high productivity region upper campanian mishash formation israel abstract a paleoecological study of molluscan fossils from the upper campanian mishash formation of southern israel was undertaken to provide new insights into the inference of bottom oxygen levels food availability and bottom water energy on high productivity seafloors quantitative data for molluscan analysis were collected from each of the main lithologies that comprises the high productivity facies mosaic of the mishash sea i e organic rich carbonates thin porcelanite and chert beds and loosely to densely packed shell beds diagenesis has obliterated faunal remains in carbonate layers pollution studies in modern environments have demonstrated the close connection between stressful conditions such as organic load toxicity and water and sediment aeration and benthic community structure as expressed through species richness evenness taxonomic composition body sizes and trace fossil assemblages these connections and behavior patterns were investigated in the varied benthic fossil assemblages of the phosphate member of the mishash formation bivalves and gastropods dominated the macrofauna in all rock types but in varying abundance and taxonomic compositions changing from diverse assemblages 15 22 species per sample to less rich ones 5 7 species and even barren intervals this range of abundance neatly describes the lateral mosaic and heterogeneous nature of the upwelling environment of the upper campanian and is comparable to the mosaic of sub facies that characterize modern upwelling facies belts today e g in the benguela upwelling system the variations shown for the macrobenthic assemblages within the mishash formation high productivity regime are associated with proximity to the high productivity center or to periods of intensified upwelling the inferred variable oxygen levels and organic load changes point up how dynamic these regions really are this is expressed in community structure and composition which vary between two extremes the low oxygen biofacies 1 is characterized by a smaller range of shell sizes infaunal deposit feeders and low species richness while the high oxygen biofacies 3 is characterized by greater ranges in shell size infaunal but also epifaunal suspension feeders and higher species richness the chert and porcelanite beds exhibit a variety of sub environments and seem to represent an intermediate facies that bridges the two extremes of biofacies 1 and 3 the above ecological criteria may provide evidence of the original carbonate environment for the thin chert and porcelanite layers the chert or porcelanite samples that contain a moderately even and rich assemblage of species intermediate to the values of the two end member facies are taken to represent a shallow water carbonate marine environment marginal to the upwelling center whereas layers of chert and porcelanite containing very low species richness and evenness are taken to characterize primary depositional environments proximal to the paleo upwelling cells

organic geochemistry and petrology of posidonia shale lower toarcian western europe the evolution from immature oil prone to overmature dry gas producing kerogen abstract kerogen concentrates as well as whole rock samples of the lower jurassic posidonia shale representing a complete maturity series from immature to highly overmature were analyzed using organic petrography palynology bulk geochemical analysis ft ir and curie point pyrolysis gc ms cp py gc ms in order to investigate changes in kerogen composition with increasing maturation vitrinite reflectance vrr ranges from 0 5 to 3 hi values reflect the maturity trend very well with little scatter in contrast tmax oi and pi values show more scatter and greater differences between kerogen concentrates and whole rock samples ft ir spectra show a decrease in functional group bands with increasing maturation which has been quantified cp py gc ms analyses indicate an increase in hydrocarbons especially for short and medium length n alkanes with a strong predominance of short length alkanes at highest maturities about 3 vrr this effect however depends also on the applied pyrolysis temperature where higher temperatures 920 c as compared to 650 c favor generation of short length n alkanes especially for samples at high levels of maturation ratios of aromatic over aliphatic hydrocarbons or alkenes over alkanes show a non steady evolution depending also on the applied pyrolysis temperatures indicating that higher pyrolysis temperatures are needed for pyrolytic alkene formation with a maximum alkene formation for samples within early overmature maturities 1 4 vrr aromaticity first decreases but increases at high levels of maturation finally weathering of the highly overmature sample 3 vrr resulted in strong oxidation of organic matter with impact on rock eval ftir and curie point pyrolysis data

coccolith strontium to calcium ratios in emiliania huxleyi the dependence on seawater strontium and calcium concentrations in recent studies the sr ca ratio of coccolithophore calcite was used as a proxy for past coccolithophore growth and calcification rates since sr and ca concentrations in seawater have not remained constant through time interpretation of sr ca data from the coccolith dominated sedimentary record requires knowledge about the incorporation of seawater sr into coccolith calcite during coccolithogenesis here we show that sr ca of emiliania huxleyi coccoliths is linearly related to seawater sr ca meaning that the sr exchange coefficient does not change with changing seawater sr ca the exchange coefficient for sr in this study 0 39 is close to values presented in the literature and is high compared with values obtained by inorganic precipitation experiments this suggests a strong effect of cell physiology on biogenic calcite precipitation in coccolithophores we present a conceptual model based on the transmembrane transport of sr and ca which explains the offset

cretaceous calcareous dinoflagellate cysts as recorder of δ44 40caseawater and paleo temperature using sr ca thermometry abstract we evaluate the potential of calcareous dinoflagellates as archives for sr ca based paleo temperature reconstructions and 44 40caseawater fluctuations on sediments from ocean drilling program expedition 113 hole 690c weddell sea southern ocean between 73 and 68 ma sr ca ratios of two cretaceous dinoflagellate species pirumella krasheninnikovii and orthopithonella globosa show a pronounced decrease consistent with a significant drop in sea surface temperature as reflected by the 18o of planktic foraminifers the apparent temperature sensitivity of the dinoflagellate cysts sr ca is 0 06 and 0 08 mmol mol c 1 using 18o derived paleo sea surface temperatures which is significant and large enough to resolve paleoenvironmental temperature changes at current analytical precision as the chemical composition of the cyst calcite appears to have a good preservation the sr ca of calcareous dinoflagellates has a potential to serve as paleo temperature proxy although the chemical composition of the cretaceous seawater and potential impacts on the cyst geochemistry is pending further inspection the ca isotope composition of the two dinoflagellate species shows identical trends of increasing 44 40ca between 73 and 67 ma the planktic foraminifer archaeoglobigerina australis and the benthic foraminifer nuttallides truempyi reveal the same increase of about 0 4 but are offset relative to the dinoflagellates by about 0 5 presumably due to species specific ca isotope fractionation bulk carbonate sediment shows significant scatter likely caused by changes in faunal composition and does not reproduce the trend revealed by the dinoflagellate and foraminifer records these observations demonstrate the importance of taxon specific records and careful determination of fractionation factors of selected archives and highlight complications arising from utilizing less suitable archives such as bulk sediments for 44 40caseawater reconstructions our records indicate strong changes in the marine ca cycle associated with the global temperature decrease towards the end of the cretaceous

the organic geochemistry of the hasbeya asphalt lebanon comparison with asphalts from the dead sea area and iraq abstract the hasbeya asphalt from lebanon and the mezar 1 asphalt from the golan heights were analyzed using current tools of petroleum geochemistry namely isotopic analyses d 13 c 34 s and molecular sterane and terpane parameters the geochemical properties of these asphalts were compared to several other asphalts from israel floating blocks of the dead sea massada nahal heimar iprg all the asphalts belong to the same genetic family e g high gammacerane and high steroid contents no diasteranes and originate from senonian upper cretaceous organic matter rich carbonate source rocks deposited in an anoxic or dysoxic perhaps hypersaline palaeoenvironment this family of asphalts is well differentiated from another famous asphalt from the near east the hit abu jir asphalt from iraq the hasbeya asphalt is slightly biodegraded whereas the mezar 1 asphalt was affected by more severe biodegradation occurrence of 25 nor hopanes isotopic ratios of asphaltenes were found to be useful in allowing differentiation of asphalts from the same genetic family this study completes the existing knowledge on dead sea asphalts by demonstrating that similar asphalts may be identified within a much larger geographic area including the golan heights and lebanon these results raise the question of whether some of the archaeological asphalts that are found in the southern fertile crescent egypt israel syria etc and which were assumed to be of dead sea origin may actually have come from hasbeya

the origin and evolution of saline formation water lower cretaceous carbonates south central texas u s a abstract land l s and prezbindowski d r 1981 the origin and evolution of saline formation water lower cretaceous carbonates south central texas u s a in w back and r letolle guest editors symposium on geochemistry of groundwater 26th international geological congress j hydrol 54 51ndash 74 systematic chemical variation exists in formation water collected from a dip section through lower cretaceous rocks of south central texas chemical variation can be explained by an interactive water rock diagenetic model the cyclic lower cretaceous shelf carbonates of the edwards group dip into the gulf of mexico coast geosyncline and can be considered to a first approximation as part of a complex aquifer contained by paleozoic basement beneath and by relatively impermeable upper cretaceous clay and chalk above the hydrodynamic character of this carbonate system is strongly controlled by major fault systems major fault systems serve as pathways for vertical movement of basinal brines into the lower cretaceous section formation water movement in this sytem has strong upfault and updip components the parent na ca cl brine originates deep in the gulf of mexico basin at temperatures between 200 and 250 c by the reaction halite detrital plagioclase quartz water albite brine other dissolved components originate by reaction of the fluid with the sedimentary phases k feldspar calcite dolomite anhydrite celestite barite and fluorite significant quantities of pb zn and fe have been mobilized as well as the brine moves updip out of the overpressured deep gulf of mexico basin and encounters limestones of the stuart city reef trend the buried platform margin small amounts of galena precipitate in late fractures continuing to rise upfault and updip the brine becomes progressively diluted on encountering significant quantities of dolomite in the backreef facies the ca rich brine causes dedolomitization although thermochemical consideration suggests that small amounts of several authigenic phases should precipitate most have yet to be found minor amounts of several kinds of calcite spar are present however as the brine evolves by dilution and by cooling no systematic changes in any cation cl ratio occur except for regular updip gain in mg as a result of progressive dedolomitization the formation water highly diluted by meteoric water eventually discharges along faults as hot mineral water

negligible temperature dependence of calcium isotope fractionation in 12 species of planktonic foraminifera the influence of temperature on calcium ca isotope fractionation during biomineralization was investigated through the paired analyses of d44 42ca via mc icp ms and d18o on the calcite tests of 12 species of planktonic foraminifera from coretop sediments samples were collected from a suite of box cores from sites between 608n and 308s in the north atlantic and west indian oceans spanning a range in sea surface temperature of 9 27 8c the d44 42casrm915a of the samples ranged from 0 21x to 0 81x over a range in the d18ovpdb of the foraminiferal calcite of between 2 3x and 2 1x the bulk of the species investigated produced calcite with an average calcite seawater ca enrichment factor e of 0 65f0 08x n 45 the globorotaliid species and a single globigerina bulloides sample were confined to the upper 0 4x of the observed range in d44 42ca values with the globorotaliids displaying a lesser degree of fractionation of 0 56f0 23x n 15 possibly as a result of physiological or metabolic processes such as the production of calcite crusts at depth leading to the depletion of internal stores of ca no significant correlation between temperature and ca enrichment factor was observed in any of the 12 species of foraminifera investigated the influence of temperature on e was close to zero for the combined non globorotaliid species 0 07f0 10 k e versus 1000 k 0 0008f0 0012x 8c1 the results suggest that the theoretically expected relationship between the ca enrichment factor and temperature can be obscured by as yet unquantified metabolic and physiological processes in nature these processes are particularly relevant to the globorotaliid species and g bulloides in this core top study consequently their effects must be better understood before laboratory determined temperature calibrations can be applied to downcore material with confidence provided that the effects of metabolic and physiological processes on e remain constant through time orbulina universa globigerinoides sacculifer neogloboquadrina pachyderma and globigerinella aequilateralis are suitable for the investigation of temporal changes in the calcium isotopic composition of seawater

interpreting rock eval pyrolysis data using graphs of pyrolizable hydrocarbons vs total organic carbon kerogen the major organic component of sedimentary rocks is commonly analyzed by rock eval pyrolysis plotting the data on a graph of s 2 vs total organic carbon toc and determining the regression equation is the best method for determining the true average hydrogen index and measuring the adsorption of hydrocarbon by the rock matrix such a plot also indicates the type of kerogen present and avoids the problem of increasing hydrogen index with total organic carbon content with the s 2 vs toc diagram the organic component of different suites of samples may be compared and their petroleum generation potentials established as an example the diagrams are used to evaluate the sedimentary environments and petroleum potential of the paleogene evaporitic sediments of the mulhouse basin alsace france

faunal and geochemical evidence for changes in intermediate water temperature and salinity in the western coral sea northeast australia during the late quaternary abstract ostracod assemblages and geochemical analyses of valves of specific ostracod taxa are used to reconstruct both qualitatively and quantitatively bottom water temperatures bwt for the last 100 000 years in the western coral sea the investigated core 51gc21 is situated in the lower reaches of the antarctic intermediate water at 1630 m water depth first we ran a principal coordinate analysis pcoa of 42 surface samples from the coral sea and then compared fossil assemblages with results of the pcoa in addition we selected well preserved speciments of the two genera krithe and bythocypris for mg ca analyses the mg ca is used to infer past changes in bwt for intermediate waters of the western coral sea results indicate large temperature fluctuations over the last 100 000 years of interest is the documentation that the bwt was similar to the present day temperature during part of isotope stage 3 comparison between our temperature record and the benthic foraminifer 18o record of core 51gc21 and with the 18o variations in seawater as reconstructed by labeyrie et al 1987 allowed assessment of past changes in bwt salinity and density thus we identify for the western coral sea three distinct periods on the basis of water mass density changes i e for isotope stage 1 stages 2 3 and 4 and stage 5 our temperature record also indicates a good correlation with the 60 s summer insolation calculations for the period between 25 000 yr b p and 75 000 yr b p comparison of our results from this study with other records from the western pacific the ontong java plateau in particular reveal the role of new guinea as an oceanographic barrier a wet phase recorded on continental australia coincides with our high bottom water temperature record for isotopic stage 3

depositional environments of the senonian chert phosphorite and oil shale sequence in israel as deduced from their organic matter composition in the upper cretaceous sequence of the negev southern israel the organic matter in phosphorites and cherts differs from that associated with oil shales in its higher content of humic substances and lower kerogen content and in its more intensive microbial alteration the n alkane distribution pattern of the oil shales phosphorites and cherts indicates that marine biota probably algae are the main organic precursors of their organic matter in some of the oil shales however some contribution of terrestrial organic matter is also evident similar high phytane pristane ratios indicate that the organic matter in the oil shales as well as in the phosphorites and cherts accumulated under reducing conditions the main differences in the organic matter composition are attributed to early diagenetic processes rather than to different biotic precursors or to late modifications due to temperature induced maturation the depositional model suggested for the sequence involves upwelling conditions at the boundary between the deep tethys and the shallow shelf which induced high organic productivity deep into the inner shelf bottom water circulation enabled intensive microbial alteration of the organic matter followed by a winnowing process leading to phosphorite formation since humification is considered an oxygen consuming reaction these processes favoured the formation of oxygen enriched humic substances and the oxidation of humic substances already present these humic substances are relatively resistant to further alteration and their conversion into kerogen is thus retarded subsequently syndepositional tectonic activity resulted in the introduction of less saline water restriction of bottom water circulation and the establishment of a density stratification in the water body consequently aeration of the bottom layer and the sediments was inhibited microbial alteration was reduced and later winnowing processes were prevented such conditions favoured the formation of kerogen directly rather than through humic substances and also favoured the preservation of most of the organic matter in the form of oil shale deposits instead of phosphorites

a cenozoic seawater sr ca record from benthic foraminiferal calcite and its application in determining global weathering fluxes a cenozoic multi species record of benthic foraminiferal calcite sr ca has been produced and is corrected for inter specific offsets typically less than 0 3 mmol mol and for the linear relationship between decreasing benthic foraminiferal sr ca and increasing water depth the water depth correction determined from holocene late glacial maximum and eocene paleowater depth transects is not vert similar0 1 mmol mol km the corrected cenozoic benthic foraminiferal sr ca record ranges from 1 2 to 2 0 mmol mol and has been interpreted in terms of long term changes in seawater sr ca enabling issues related to higher resolution variability in sr ca to be ignored we estimate that seawater sr ca was not vert similar1 5 times modern values in the late cretaceous but declined rapidly into the paleogene following a minimum in the eocene seawater sr ca increased gradually through to the present day with a minimum superimposed on this trend centered in the late miocene by assuming scenarios for changing seawater calcium concentration and using published carbonate accumulation rate data combined with suitable values for sr partition coefficients into carbonates the seawater sr ca record is used to estimate global average river sr fluxes these fluxes are used in conjunction with the seawater strontium isotope curve and estimates of hydrothermal activity tectonic outgassing to calculate changes in global average river 87sr 86sr through the cenozoic the absolute magnitude of sr fluxes and isotopic compositions calculated in this way are subject to relatively large uncertainties nevertheless our results suggest that river sr flux increased from 35 ma to the present day roughly two fold accompanied by an overall increase in 87sr 86sr by not vert similar0 to 0 001 between 75 and 35 ma river 87sr 86sr also increased by not vert similar0 001 to 0 002 but was accompanied by a decrease two to three fold in river sr flux

calcitization dedolomitization of jurassic dolostones lebanon results from petrographic and sequential geochemical analyses calcitized jurassic dolostones from central mount lebanon kesrouane formation are discussed utilizing petrographic mineralogical and geochemical data in particular two sequential extraction methods for both major trace elements and stable isotope analyses provide results that support and refine conventional bulk analyses data the new data demonstrate that the major dedolomitization phase of the investigated jurassic carbonates occurred as a result of the migration of karst related meteoric waters characterized by soil derived carbon and estimated 18ov smow composition between 7 2 and 3 4 into previously dolomitized horizons within the limestone rock during the final uplift and emergence of mount lebanon after palaeogene time the study demonstrates that in this case the mechanisms of dedolomitization and their resulting fabrics are controlled primarily by the texture of the original dolomite rock pervasively dolomitized rocks where the micritic matrix is entirely dolomitized show calcitization mainly through dissolution precipitation by contrast the rock textures that still include a considerable amount of limey micritic matrix spared from dolomitization are more prone to mole per mole and mimic replacement of the dolomite crystals by calcite

organic geochemical characterization of santonian to early campanian organic matter rich marls sondage no 1 cores as related to oae3 from the tarfaya basin morocco abstract in addition to previously analyzed sediments of cenomanian to santonian age in the tarfaya sondage no 2 well this study presents the results of a stratigraphically younger interval of santonian to early campanian age in the adjacent well tarfaya sondage no 1 this interval is part of the oceanic anoxic event 3 oae3 which occurred mainly in the atlantic realm due to known high quality source rocks related to oaes i e cenomanian turonian the investigated sample section was tested for the quality quantity and kind of organic matter om describing also the depositional environment the study was carried out by means of i elemental analysis c org caco 3 ts ii rock eval pyrolysis iii vitrinite reflectance measurements iv gas chromatography flame ionization detection gc fid and v gc mass spectrometry gc ms total content of organic carbon c org values for the hydrogen index hi mainly in the range 500 700 mg g c org and s 2 values 10 40 mg g rock support the assumption of a high petroleum generation potential in these upper cretaceous sediments ts c org ratios as well as pristane phytane ratios indicate variable oxygen contents during sediment deposition representing a typical depositional setting for the late cretaceous and are in good agreement with previously analyzed data in the tarfaya basin phyto and zoo plankton were identified as marine sourced all of the investigated early campanian and santonian samples are immature with some tendencies to early maturation these results are based on vitrinite reflectance 0 3 0 4 vr r t max values 409 425 c production indices pi s 1 s 1 s 2 n alkane ratios i e carbon preference index as the deposition of these sediments is time related to oae3 the depositional environment was characterized by oxygen deficiency or even anoxic bottom water conditions this situation was favored during the cretaceous greenhouse climate by limited oxygen solubility in the then warmer ocean water furthermore local factors related to nutrient supply and primary bioproductivity led to the exceptionally thick upper cretaceous organic matter rich sedimentary sequence of the tarfaya basin

paleoceanographic events and deep sea ostracodes eight recognized or theorized paleoceanographic events during the past 70 million years were tested against changes in the global deep sea benthic ostracode fauna two events the sudden cretaceous tertiary boundary event at 66 million years ago and the more gradual 40 million year event formation of the psychrosphere show up most dramatically before the 40 million year event ostracodes freely radiated into the deeper water regions but were provincial the development of thermal stratification isolated these deep water taxa mostly the survivors of the cretaceous tertiary boundary event which adapted to a new free flowing but more frigid ecosystem and spread rapidly throughout the world

characterization of lowest oxygen environments within ancient upwelling environments benthic foraminifera assemblages abstract the upper campanian mishash formation of southern israel was deposited within the southern tethys upwelling belt with sea floors beneath this system characterized by poorly ventilated sediments approaching anoxia this study was aimed at tracking the oxygen poor gradient using benthic foraminiferal assemblages of organic rich carbonates that are devoid of benthic macro invertebrates and trace fossils quantitative data were gathered on foraminiferal faunas from four sections namely zin saraf qazra ashosh omer and qilt from three basins affected by upwelling four distinct benthic foraminiferal assemblages characterize the organic rich carbonate facies b assemblages a d these assemblages are distinguished by their species richness and composition relative abundance and dominance patterns the low diversity buliminid dominated faunas correlate with high up to 25 wt total organic carbon levels and inferred pore water oxygen levels range from nearly anaerobic to dysaerobic up to 0 1 ml o2 l the zin and qazra ashosh basins in southern israel have representation of assemblages a and b indicative of the most oxygen depleted environments assemblages c and d are more common in better ventilated environments such as the qazra omer basin of southern israel and the qilt basin to the northeast nonetheless all these basins have benthic assemblages indicative of low oxygen pore waters

paleoceanographic reconstruction of the late cretaceous oil shale of the negev israel integration of geochemical and stable isotope records of the organic matter the levantine high productivity system was an extensive coastal upwelling that operated in the late cretaceous along the se tethyan margin this study focuses on the top phosphate member of the mishash formation and the oil shale member osm of the ghareb formation latest campanian early maastrichtian which represent the last phase of this high productivity system in the negev israel bulk organic matter toc 13corg 15norg c n and pristane phytane pr ph ratios were studied for reconstruction of seafloor and water column depositional environments our records indicate a gradual decrease with time in surface water productivity in the osm and a marked weakening at the overlying marl member high c n ratio along with relatively low 15norg 4 to 6 and 13corg 29 to 28 probably reflect significant diagenetic preferential loss of nitrogen rich organic compounds enriched with 15n and 13c isotopes e g proteins this along with the low pr ph values 0 11 0 7 indicate oxygen depleted bottom water anoxia dysoxia during the deposition of the top phosphate member and the osm the moderate gradual upward increase in 15norg and in pr ph values and the decrease of toc and c n values from the top phosphate member through the osm indicate transition from anoxic phosphate lower osm to dysoxic middle upper osm conditions this environmental trend is consistent with co occurring foraminiferal assemblages in the studied succession and implies that the benthic species in the negev sequence were adapted to persistent minimum oxygen conditions by performing complete denitrification as recently found in many modern benthic foraminifera

biological control of calcium isotopic abundances in the global calcium cycle measurements of 44ca 40ca expressed as 44ca were made on igneous rocks and on shell and bone material from modern organisms to investigate the magnitude and origins of calcium isotopic fractionation in nature the results document a span of 4 in 44ca measured with the double spike technique to a precision of 0 15 volcanic rocks including basalt and rhyolite show little variability and cluster near 44ca 0 0 2 systematic analysis of biological samples indicates that biological processing of calcium discriminates against heavy isotopes and that biological fractionation is the primary generator of calcium isotopic fractionation in nature preliminary data suggest that calcium becomes isotopically lighter as it moves through food chains calcium carbonate shells of marine microorganisms and deep sea carbonate ooze have 44ca about 1 0 lower than seawater this fractionation causes seawater to be enriched in heavy calcium 44ca 0 9 relative to igneous rocks marine organisms consequently are isotopically heavier than their terrestrial counterparts at similar trophic level the calcium isotopic composition of living and fossil organisms may record information on diet and environment

orbital and suborbital variability in north atlantic bottom water temperature obtained from deep sea ostracod mg ca ratios abstract magnesium calcium mg ca ratios were measured in the deep sea ostracod crustacea genus krithe from chain core 82 24 4pc from the western mid atlantic ridge 3427 m in order to estimate ocean circulation and bottom water temperature bwt variability over the past 200 000 years mg ca ratios have been used as a paleothermometer because the ratios are controlled primarily by ambient water temperatures at the time the organism secretes its adult carapace over the past two glacial interglacial cycles mg ca values oscillated between about 7 mmol mol and 12 mmol mol equivalent to a bwt range of 0 to 3 5 c the lowest values were obtained on specimens from glacial marine isotope stages miss 2 4 and 6 the highest values were obtained from specimens from the early part of the holocene interglacial mis 1 and also from miss 5 and 7 these trends suggest that bwts in the north atlantic ocean fluctuate over orbital time scales suborbital variability in mg ca ratios and bwt was also observed for the past 100 000 years ratios rose from 8 mmol mol to 10 mmol mol implying a bwt increase of 1 to 3 c during 14 mg ca excursions the highest ratios were found in krithe dated at approximately 32 36 38 43 48 73 85 and 93 ka although the age model for the chain 82 24 4pc and temporal resolution do not allow precise correlation some of these deep sea bottom temperature excursions appear to correspond to heinrich events recorded in other regions of the north atlantic and perhaps dansgaard oeschger interstadial events recorded in greenland ice cores if confirmed this would support the hypothesis that millennial scale oscillations of climate in the north atlantic are capable of affecting global climate via thermohaline circulation changes

reconstruction of caribbean sea surface temperature and salinity fluctuations in response to the pliocene closure of the central american gateway and radiative forcing using δ44 40ca δ18o and mg ca ratios the 18o values of planktonic foraminifera increased in the caribbean by about 0 5 relative to the equatorial east pacific values between 4 6 and 4 2 ma as a consequence of the closure of the central american gateway cag this increase in 18o can be interpreted either as an increase in caribbean sea surface mixed layer salinity sss or as a decrease in sea surface temperatures sst this problem represents an ideal situation to apply the recently developed paleotemperature proxy 44 40ca together with mg ca and 18o on the planktic foraminifer globigerinoides sacculifer from odp site 999 although differences in absolute temperature calibration of 44 40ca and mg ca exist the general pattern is similar indicating a sst decrease of about 2 3 c between 4 4 and 4 3 ma followed by an increase in the same order of magnitude between 4 3 and 4 0 ma correcting the 18o record for this temperature change and assuming that changes in global ice volume are negligible the salinity induced planktonic 18o signal decreased by about 0 4 between 4 4 and 4 3 ma and increased by about 0 9 between 4 3 and 4 0 ma in the caribbean the observed temperature and salinity trends are interpreted to reflect the restricted exchange of surface water between the caribbean and the pacific in response to the shoaling of the panamanian seaway possibly accompanied by a southward shift of the intertropical convergence zone itcz between 4 4 and 4 3 ma differences in mg ca and 44 40ca derived temperatures can be reconciled by corrections for secular variations of the marine mg casw and 44 40ca a salinity effect on the mg ca ratio and a constant temperature offset of 2 5 c between both sst proxy calibrations

geochemical and petrographic analyses of new petroleum source rocks from the onshore upper jurassic and lower cretaceous of lebanon abstract the recent interest in the lebanese petroleum potential led to new studies mainly concerning marine petroleum source rocks without taking in consideration the dysodiles and other associated facies from the upper jurassic and the lower cretaceous these organic rich outcrops of metric thickness max 3 m are of limited lateral extension and often found next to volcanic deposits sixty three samples were collected from 25 different localities and were subdivided into three facies that are presented in this paper i dysodiles formed by the superposition of millimetric layers that are easy to separate ii dysodiles like with distinct but more compacted layers iii non dysodiles where the layering is not visible the aim of this work is to assess the origin of these organic rich rocks and to evaluate their source rock potential we used herein rock eval pyrolysis elemental analysis palynofacies observation organic petrography and molecular geochemical analyses rock eval pyrolysis reveals a very good to excellent source rock potential for all above cited rock types with average total organic carbon toc of 14 7 for the dysodiles 19 12 for the dysodiles like and 13 9 for the non dysodiles hydrogen index hi and oxygen index oi values indicate a type i to ii kerogen for the dysodiles average hi 649 162 mg hc g toc type i to ii kerogen for the dysodiles like average hi 340 182 mg hc g toc and type iii kerogen for the non dysodiles average hi 145 42 mg hc g toc the dominance of fluorescent amorphous organic matter aom and alginite macerals confirm an algal bacterial source of organic matter for the dysodiles the presence of opaque aom phytoclasts sporinites and cutinites macerals suggests a variable terrestrial organic matter input for the dysodiles like and non dysodiles maturity parameters such as tmax values on average 428 7 c for dysodiles 429 6 c for dysodiles like and 424 10 c for non dysodiles vitrinite reflectance 1 indicate that the organic matter is still thermally immature the present study sheds light on the long forgotten dysodile shales and similar material and their importance as potential source rocks or oil shales a comparison with local and regional source rocks is provided in order to emphasize the specific character of the dysodile deposits

source rock potential and depositional environment of upper cretaceous sedimentary rocks abu gharadig basin western desert egypt an integrated palynological organic and inorganic geochemical study abstract the abu gharadig basin in the northern part of the western desert egypt is among the most important petroleum provinces in egypt here cenomanian to santonian rocks of bahariya formation and abu roash a g members from the gpt 3 well were investigated for their depositional environment kerogen quality petroleum generation potential and thermal maturity by geochemical petrological and palynological methods the sediments of the bahariya and abu roash formations excluding the abu roash f member represent variable shallow marine environments with poor preservation of marine organic matter whereas there is an excellent preservation in the abu roash f member the basal part of this member is characterized by anoxic carbonate rich depositional conditions high toc values up to 7 high hi up to 700 mghc gtoc and liptinite dominated organic matter depletion of iron leads to sulfur incorporation into organic matter which is reflected in high thiophene benzene ratios above sediments are enriched in terrestrial elements fe ti as well as k and mn this pattern and the occurrence of the fresh brackish water algae botryococcus suggests a regression phase during deposition the upper part of the abu roash f member is again characterized by fully marine suboxic conditions and a lower thiophene benzene ratio the source rock section demonstrates lower thermal maturity compared to the above and below sections based on all microscopic pyrolysis and biomarker data this indicates thermal maturity retardation suppression most likely due to a different organic facies and early diagenetic transformation of kerogen as indicated by the geochemical and palynological data the source rock heterogeneity indicates a relatively shallow marine environment where the changes in bottom water conditions are very sensitive to sea level fluctuations residual oil characterization reveals two reservoir compartments which are in the abu roash d and c members the abu roash f source rocks are compared with time equivalent sediments in the tarfaya basin in morocco which represent more distal settings the more proximal group a is characterized by s fe ratios between 0 57 and 0 67 indicating suboxic conditions it has toc and hi values not exceeding 4 and 600 mghc gtoc respectively at variable caco3 contents the more distal tarfaya sediments group b have higher toc and hi as well as high organic sulfur contents group a is higher in terrigenous element concentrations the tmax of immature source rocks ranges from 410 to 415 c in organic sulfur rich samples and from 420 to 430 c in organic sulfur poor samples revealing an important impact of organic facies on maturity parameters furthermore there is an inverse relationship between s fe and al2o3 toc which might become an important tool in paleoenvironmental reconstructions as well as petroleum source rock studies

source rock potential of the phosphorite bituminous chalk marl sequence in jordan abstract the phosphorite and the overlying oil shale succession in central and eastern jordan has been studied for its organic matter composition maturation hydrocarbon potential and sedimentological implications pristine phosphorite was authigenically precipitated from interstitial solutions in ventilated environments later they were reworked and winnowed to produced the granular phosphorites possibly as wave or storm sand bodies the oil shale was deposited in the same basins where restricted water circulation and subsequent hypersalinity led to more reducing conditions and better organic matter preservation both facies represent a high bio productivity regime associated with paleo upwelling on the shallow southern epicontinental shelf of the tethys ocean the organic matter is dominantly amorphous and the extractable part is high kerogen is type ii s to type iii all maturity parameters investigated proved it to be immature e g r0

karstification without carbonic acid bedrock dissolution by gypsum driven dedolomitization aggressive karstification can take place where dolomite and gypsum are in contact with the same aquifer gypsum dissolution drives the precipitation of calcite thus consuming carbonate ions released by dolomite lake banyoles in northeastern spain is a karst lake supplied by sublacustrine springs and karstic collapse is occurring in the immediate vicinity of the lake lake water is dominated by mg ca and so 4 hco 3 and is supersaturated with calcite that is actively accumulating in lake sediments water chemistry sulfur isotope composition local stratigraphy and mass balance modelling suggest that the primary karst forming process at at lake banyoles is dedolomitization of basement rocks driven by gypsum dissolution karstification takes place along the subsurface contact between the gypsiferous beuda formation and the dolomitic perafita formation this process is here recognized for the first time to cause karstification on a large scale this is significant because it proceeds without the addition of soil generated carbonic acid gypsum driven dedolomitization may be responsible for other karstic systems heretofore attributed to soil generated carbonic acid