experimental study of fluid transport processes in the matrix system of the european organic rich shales i scandinavian alum shale abstract this contribution presents results from a laboratory study investigating the fluid gas water transport properties in the matrix system of the scandinavian alum shale the maturity of the organic matter of the shale samples ranged between 0 5 and 2 4 vitrinite reflectance vr r gas he ar ch 4 and water flow properties were determined at effective stresses ranging between 5 and 30 mpa and a temperature of 45 c the effects of different controlling factors parameters on the fluid conductivity including permeating fluid moisture content anisotropy heterogeneity effective stress pore pressure and load cycling were analyzed and discussed pore volume measurements by helium expansion were conducted under controlled in situ effective stress conditions on a limited number of plugs drilled parallel and perpendicular to bedding for alum shale the intrinsic permeability coefficients measured parallel and perpendicular to bedding 6 10 22 8 10 18 m 2 were within the range previously reported for other shales and mudstones permeability coefficients were strongly dependent on permeating fluid moisture content anisotropy effective stress and other sample to sample variations the intrinsic absolute permeabilities measured with helium were consistently higher up to five times than those measured with argon and methane permeability coefficients he ch 4 measured on a dry sample were up to six times higher than those measured on an as received sample depending on effective stress the effect of moisture on measured permeability coefficients became more significant as effective stress increased permeability coefficients he ch 4 measured parallel to bedding were up to more than one order of magnitude higher than those measured perpendicular to bedding parallel to bedding all samples showed a nonlinear reduction in permeability with increasing effective stress 5 30 mpa the stress dependence of permeability could be well described by an exponential relationship

the role of event beds in the preservation of organic carbon in fine grained sediments analyses of the sedimentological processes operating during deposition of the whitby mudstone formation toarcian lower jurassic preserved in northeast england abstract geologists have recently observed that source rocks commonly contain a wide variety of microfabrics including diminutive ripples and burrows the existence of these fabrics challenges the assumption that persistent bottom water anoxia and low energy conditions are necessary prerequisites for enhanced organic carbon preservation in these units in order to enhance our understanding of the depositional and diagenetic processes responsible for organic carbon preservation in these strata the lower jurassic whitby mudstone formation which contains mudstones with up to 14 2 total organic carbon has been investigated using optical electron optical and geochemical methods four thinly bedded mudstone lithofacies were identified a silt bearing clay rich mudstones b clay rich mudstones c clay calcareous nannoplankton and organic carbon bearing mudstones and d cement rich mudstones internally individual beds are typically sharp based and normally graded they are either laminated partially bioturbated or homogenized where depositional fabrics are preserved pellets silt lags ripple lamination shell pavements wave enhanced sediment gravity flows of fluid mud and organo minerallic aggregates have been observed the presence of up to 14 2 toc in units that are sharp based and normally graded suggests that mass flows possibly generated by storms likely influenced sedimentation during deposition of these mudstones the abundant organo minerallic fabrics in these units indicates that at least some of the organic carbon was delivered to the seafloor as marine snow aggregates that likely formed in the water column following phytoplankton blooms homogenization of bed tops indicates that between sediment delivery episodes an infauna was able to colonize the seafloor implying that the bottom waters were at least partly oxygenated during these intervals these fabrics suggest that during deposition of the whitby mudstone formation organic carbon was being preferentially preserved below regions of high primary organic production the close association between sharp based graded beds and organo minerallic aggregates indicates that large volumes of organic carbon were delivered episodically to the seafloor and that conditions at the sediment water interface were episodically dynamic here organic carbon is likely to have been preferentially preserved because the frequency of depositional events was sufficiently high to minimize both oxidant diffusion into the sediment and organic carbon mineralization while bottom water anoxia may have developed during the phytoplankton blooms it was unlikely to have been persistent because the microfabrics present indicate that there was sufficient time and oxygen available for an infauna to disrupt the sediment between deposition events

the importance of shale composition and pore structure upon gas storage potential of shale gas reservoirs abstract the effect of shale composition and fabric upon pore structure and ch 4 sorption is investigated for potential shale gas reservoirs in the western canadian sedimentary basin wcsb devonian mississippian d m and jurassic shales have complex heterogeneous pore volume distributions as identified by low pressure co 2 and n 2 sorption and high pressure hg porosimetry thermally mature d m shales 1 6 2 5 vro have dubinin radushkevich d r co 2 micropore volumes ranging between 0 3 and 1 2 cc 100 g and n 2 bet surface areas of 5 31 m 2 g jurassic shales which are invariably of lower thermal maturity ranging from 0 9 to 1 3 vro than d m shales have smaller d r co 2 micropore volumes and n 2 bet surface areas typically in the range of 0 23 0 63 cc 100 g co 2 and 1 9 m 2 g n 2 high pressure ch 4 isotherms on dried and moisture equilibrated shales show a general increase of gas sorption with total organic carbon toc content methane sorption in d m shales increases with increasing toc and micropore volume indicating that microporosity associated with the organic fraction is a primary control upon ch 4 sorption sorption capacities for jurassic shales however can be in part unrelated to micropore volume the large sorbed gas capacities of organic rich jurassic shales independent of surface area imply a portion of ch 4 is stored by solution in matrix bituminite solute ch 4 is not an important contributor to gas storage in d m shales structural transformation of d m organic matter has occurred during thermal diagenesis creating and or opening up microporosity onto which gas can sorb as such d m shales sorb more ch 4 per weight percent wt toc than jurassic shales inorganic material influences modal pore size total porosity and sorption characteristics of shales clay minerals are capable of sorbing gas to their internal structure the amount of which is dependent on clay type illite and montmorillonite have co 2 micropore volumes of 0 78 and 0 79 cc 100 g n 2 bet surface areas of 25 and 30 m 2 g and sorb 2 9 and 2 1 cc g of ch 4 respectively dry basis a reflection of microporosity between irregular surfaces of clay platelets and possibly related to the size of the clay crystals themselves mercury porosimetry analyses show that total porosities are larger in clay rich shales compared to silica rich shales due to open porosity associated with the aluminosilicate fraction clay rich sediments low si al ratios have unimodal pore size distributions

the early toarcian and cenomanian turonian anoxic events in europe comparisons and contrasts two intervals of mesozoic time are demonstrably of sufficient geological brevity to qualify readily for the term anoxic event the earlyfalciferum zone orexaratum subzone of the toarcian and thewhiteinella archaeocretacea interval zone that straddles the cenomanian turonian boundary both periods of time saw regional deposition of anomalously organic rich strata black shales accompanied by a positive 2 pdb carbon isotope excursion in coeval biogenic carbonates and significant faunal change the duration of both events was probably less than half a million years and both were preceded by regional erosion and possible upwelling coincident sea level rise and transgression is likely a european view of these events however spotlights some significant differences whereas thefalciferum zone organic matter is generally more concentrated and more hydrogen rich on the palaeo european shelf than on the tethyan continental margins the reverse holds true for the black shales formed during thewhiteinella archaeocretacea interval zone furthermore the carbon isotope composition offalciferum zone organic matter from both north european and tethyan sites is anomalously negative compared to that developed in thewhiteinella archaeocretacea interval zone differing planktonic organisms may have been involved and their possible diverse ecological requirements may go some way to explaining the nature and distribution of facies deposited during these two events

rapid climate change and conditional instability of the glacial deep ocean from the thermobaric effect and geothermal heating previous results from deep sea pore fluid data demonstrate that the glacial deep ocean was filled with salty cold water from the south this salinity stratification of the ocean allows for the possible accumulation of geothermal heat in the deep sea and could result in a water column with cold fresh water on top of warm salty water and with a corresponding increase in potential energy for an idealized 4000 dbar two layer water column we calculate that there are 10 6j m 2 0 2j kg of potential energy available when a 0 4 psu salinity contrast is balanced by a 2 c temperature difference this salt based storage of heat at depth is analogous to convectively available potential energy cape in the atmosphere the thermobaric effect in the seawater equation of state can cause this potential energy to be released catastrophically because deep ocean stratification was dominated by salinity at the last glacial maximum lgm the glacial climate is more sensitive to charging this thermobaric capacitor and can plausibly explain many aspects of the record of rapid climate change our mechanism could account for the grouping of dansgaard oeschger events into bond cycles and for the different patterns of warming observed in ice cores from separate hemispheres

constraint of the co2 rise by new atmospheric carbon isotopic measurements during the last deglaciation 1 the causes of the 80 ppmv increase of atmospheric carbon dioxide co2 during the last glacial interglacial climatic transition remain debated we analyzed the parallel evolution of co2 and its stable carbon isotopic ratio 13co2 in the european project for ice coring in antarctica epica dome c ice core to bring additional constraints agreeing well but largely improving the taylor dome ice core record of lower resolution our 13co2 record is characterized by a w shape with two negative 13co2 excursions of 0 5 during heinrich 1 and younger dryas events bracketing a positive 13co2 peak during the bolling allerod warm period the comparison with marine records and the outputs of two c cycle box models suggest that changes in southern ocean ventilation drove most of the co2 increase with additional contributions from marine productivity changes on the initial co2 rise and 13co2 decline and from rapid vegetation buildup during the co2 plateau of the bolling allerod

stomatal proxy record of co2 concentrations from the last termination suggests an important role for co2 at climate change transitions a new stomatal proxy based record of co2 concentrations co2 based on betula nana dwarf birch leaves from the hasseldala port sedimentary sequence in south eastern sweden is presented the record is of high chronological resolution and spans most of greenland interstadial 1 gi 1a to 1c allerod pollen zone greenland stadial 1 gs 1 younger dryas pollen zone and the very beginning of the holocene preboreal pollen zone the record clearly demonstrates that i co2 were significantly higher than usually reported for the last termination and ii the overall pattern of co2 evolution through the studied time period is fairly dynamic with significant abrupt fluctuations in co2 when the climate moved from interstadial to stadial state and vice versa a new loss on ignition chemical record used here as a proxy for temperature lends independent support to the hasseldala port co2 record the large amplitude fluctuations around the climate change transitions may indicate unstable climates and that tippingpoint situations were involved in last termination climate evolution the scenario presented here is in contrast to co2 records reconstructed from air bubbles trapped in ice which indicate lower concentrations and a gradual linear increase of co2 through time the prevalent explanation for the main climate forcer during the last termination being ocean circulation patterns needs to re examined and a larger role for atmospheric co2 considered

stomatal evidence for a decline in atmospheric co2 concentration during the younger dryas stadial a comparison with antarctic ice core records a recent high resolution record of late glacial co2 change from dome concordia in antarctica reveals a trend of increasing co2 across the younger dryas stadial gs 1 these results are in good agreement with previous antarctic ice core records however they contrast markedly with a proxy co2 record based on the stomatal approach to co2 reconstruction which records a ca 70 ppm mean co2 decline at the onset of gs 1 to address these apparent discrepancies we tested the validity of the stomatal based co2 reconstructions from kru akenes by obtaining further proxy co2 records based on a similar approach using fossil leaves from two independent lakes in atlantic canada our late glacial co2 reconstructions reveal an abrupt ca 77 ppm decrease in atmospheric co2 at the onset of the younger dryas stadial which lagged climatic cooling by ca 130 yr furthermore the trends recorded in the most accurate high resolution ice core record of co2 from dome concordia can be reproduced from our stomatal based co2 records when time averaged by the mean age distribution of air contained within dome concordia ice 200 to 550 yr if correct our results indicate an abrupt drawdown of atmospheric co2 within two centuries at the onset of gs 1 suggesting that some re evaluation of the behaviour of atmospheric co2 sinks and sources during times of rapid climatic change such as the late glacial may be required copyright 2002 john wiley sons ltd journal of quaternary science

carbon isotope constraints on the deglacial co2 rise from ice cores the stable carbon isotope ratio of atmospheric co2 13catm is a key parameter in deciphering past carbon cycle changes here we present 13catm data for the past 24 000 years derived from three independent records from two antarctic ice cores we conclude that a pronounced 0 3 per mil decrease in 13catm during the early deglaciation can be best explained by upwelling of old carbon enriched waters in the southern ocean later in the deglaciation regrowth of the terrestrial biosphere changes in sea surface temperature and ocean circulation governed the 13catm evolution during the last glacial maximum 13catm and atmospheric co2 concentration were essentially constant which suggests that the carbon cycle was in dynamic equilibrium and that the net transfer of carbon to the deep ocean had occurred before then

implications of paleozoic and mesozoic rocks in the soda mountains northeastern mojave desert california for late paleozoic and mesozoic cordilleran orogenesis study of the soda mountains in the northeastern mojave desert revealed new stratigraphic and structural features of this area a section of cambrian to jurassic rocks in the area displays various features of regional importance lower permian rocks have depositional characteristics indicative of mass flow deposition contrasting with underlying shelf strata and platformal rocks exposed in areas to the east these rocks are similar to deep water rocks exposed to the north in eastern california lower triassic rocks are named the silver lake formation and consist of shallow water siltstone and carbonate that contain conglomerate with volcanic and gneissic ciasts these latter rocks record the possible presence of permian triassic igneous and deformational activity in the area a complicated deformational history is also evident from this study we interpret several west dipping low angle faults active during intrusion of middle cretaceous granitoids to be normal faults rather than thrust faults as they were originally considered structures in the soda mountains probably correlate with similar ones in surrounding areas collectively the local structures imply a complicated stress regime during emplacement of the middle cretaceous plutonic rocks these new data imply that large thrusts faults placing paleozoic rocks over mesozoic rocks are not present in this area upper paleozoic and lower mesozoic rocks also tie this area to the western mojave desert indicating that strike slip faults with several hundred kilometers of displacement do not separate the two areas

late glacial and early holocene variations in atmospheric co2 concentration indicated by high resolution stomatal index data data from ice cores suggest that late glacial and early holocene atmospheric co2 variations were rather conservative the most important change being a gradual younger dryas increase by contrast palaeo co2 records based on the inverse relationship between co2 partial pressure and stomatal frequency of terrestrial plant leaves reflect a more dynamic co2 evolution including an abrupt decrease at the allerod younger dryas transition here we present a late glacial and early holocene co2 record based on stomatal index data from leaves preserved in the sediments of a small lake in southwestern sweden three independent records constructed from stomatal index data of salix polaris salix herbacea and betula nana leaves were combined to form a high resolution co2 reconstruction for the period 12 800 10 800 cal yr bp atmospheric co2 concentrations were found to have decreased rapidly from c 260 ppmv to 210 215 ppmv within 200 years during the allerod gi 1 younger dryas gs 1 transition after 100 200 years co2 concentration started to gradually increase to 270 290 ppmv at the end of the younger dryas stadial gs 1 co2 concentrations were relatively stable during the early holocene except for a short lived period of lower 240 250 ppmv values c 11350 11200 cal yr bp this late glacial and early holocene co2 evolution partly resembles previous stomatal based co2 reconstructions and the overall trend is almost identical to that seen in ice core records the amplitude of change is however markedly higher in the swedish stomatal based record compared to the ice cores this difference may partly be accounted for by the inherent smoothing of ice core co2 records caused by diffusion but a major part of the difference in amplitude between ice core and stomatal based records still remains to be explained based on our reconstruction atmospheric co2 may have played an important role in climate dynamics during the last deglaciation c 2003 elsevier b v all rights reserved less

the 1999 marsokhod rover mission simulation at silver lake california mission overview data sets and summary of results we report on a field experiment held near silver lake playa in the mojave desert in february 1999 with the marsokhod rover the payload descent imager pancam mini tes and robotic arm camera data volumes and data transmission receipt windows simulated those planned for the mars surveyor mission selected for 2001 a central mast with a pan and tilt platform at 150 cm height carried a high resolution color stereo imager to simulate the pancam and a visible near infrared fiberoptic spectrometer operating range 0 35 2 5 m monochrome stereo navigation cameras were mounted on the mast and the front and rear of the rover near the wheels a field portable infrared spectroradiometer operating range 8 14 m simulated the mini tes a robotic arm camera capable of close up color imaging at 23 m pixel resolution was used in conjunction with the excavation of a trench into the subsurface the science team was also provided with simulated images from the mars descent imager and orbital panchromatic and multispectral imaging of the site obtained with the french spot airborne thermal infrared mapping spectrometer and landsat thematic mapper instruments commands sequences were programmed and sent daily to the rover and data returned were limited to 40 mbits per communication cycle during the simulated mission 12 commands were uplinked to the rover it traversed 90 m six sites were analyzed 11 samples were collected for laboratory analysis and over 5 gbits of data were collected twenty two scientists unfamiliar with the location of the field site participated in the science mission from a variety of locations accessing data via the world wide web remote science interpretations were compared with ground truth from the field and laboratory analysis of collected samples using this payload and mission approach the science team synergistically interpreted orbital imaging and infrared spectroscopy descent imaging rover based imaging infrared spectroscopy and microscopic imaging to deduce a consistent and largely correct interpretation of the geology mineralogy stratigraphy and exobiology of the site use of imaging combined with infrared spectroscopy allowed source outcrops to be identified for local rocks on an alluvial fan different lithologies were distinguished both near the rover and at distances of hundreds of meters or more subtle differences such as a contact between dolomite and calcite were identified at a distance of 0 5 km a biomarker for endolithic microbiota a plausible life form to be found on mars was successfully identified microscopic imaging of soils extracted from the surface and subsurface allowed the mineralogy and fluvial history of the trench site to be deduced the scientific productivity of this simulation shows that this payload and mission approach has high science value and would contribute substantially to achieving the goals of mars exploration

organic matter maturation under the influence of a deep intrusive heat source a natural experiment for quantitation of hydrocarbon generation and expulsion from a petroleum source rock toarcian shale northern germany four shallow boreholes were drilled in the hils syncline northern germany in order to determine quantitatively the amount of hydrocarbons generated and expelled during maturation of a typical kerogen type ii bearing source rock the holes penetrated the carbonceous lias shales posidonia shale lower toarcian and part of the adjacent dogger and lias mudstones the maturity of the organic matter in the cores recovered ranges from immature 0 48 r0 to overmature 1 45 r0 due to location of the hils syncline in the vicinity of the vlotho massif which is deep seated intrusive body facies variations of the lias within the short geographical distances in the study area are negligible organic matter mass balance calculations were based on detailed organic geochemical analyses of residual material in the lias shales kerogen bitumen etc and on the evidence of a uniform initial composition of these sediments in the study area dead carbon determinations supported this latter criterion but were not used as a parameter in the calculations about 50 of the initial kerogen was transformed into oil gas and inorganic compounds during the vitrinite reflectance increase from 0 48 to 0 88 ro and only marginally more during the maturity increase from 0 88 to 1 45 ro only a small portion of the generated material remained in the source rock even at a relatively early stage of generation 0 68 ro expulsion efficiency of oil plus gas reached a value of 86 at the end of the main generation stage 0 88 ro

microstructural characteristics of the whitby mudstone formation uk when trying to improve gas productivity from unconventional sources a first aim is to understand gas storage and gas flow potential through the rock by investigating the microstructure mineralogy and matrix porosity of unfractured shale the porosity and mineralogy of the mulgrave shale member of the whitby mudstone formation uk were characterized using a combination of microscopy x ray diffraction and gas adsorption methods on samples collected from outcrops the whitby mudstone is an analogue for the dutch posidonia shale which is a possible unconventional source for gas the mulgrave shale member of the whitby mudstone formation can microstructurally be subdivided into a fossil rich 15 upper half and a sub mm mineralogically laminated lower half all clasts are embedded within a fine grained matrix all grains 100 nm is in the order of 0 5 2 5 and shows a non connected pore network in 2d gas adsorption n2 ar he porosity pore diameters down to 2 nm has been measured to be 0 3 7 overall more than 40 of the visible porosity is present within the matrix comparing the whitby mudstone formation to other producing gas shales shows that the rock plots in the low porosity and high clay mineral content range which could imply that whitby mudstone shales could be less favourable to mechanical fracturing than other gas shales estimated permeability indicates values in the micro to nano darcy range

synchronous records of pco2 and δ14c suggest rapid ocean derived pco2 fluctuations at the onset of younger dryas just before the onset of the younger dryas yd cold event several stomatal proxy based pco2 records have shown a sharp increase in atmospheric co2 concentration pco2 of between ca 50 and 100 ppm followed by a rapid decrease of similar or even larger magnitude here we compare one of these records a high resolution pco2 record from southern sweden with the intcal13 record of radiocarbon d 14 c the two records show broadly synchronous fluctuations at the yd onset specifically the intcal13 record documents decreasing d 14 c just before the yd onset when pco2 peaks consistent with a source of old co2 from the deep ocean we propose that this fluctuation occurred due to a major ocean flushing event the cause of the flushing event remains speculative but could be related to the hypothesis of the glacial ocean as a thermobaric capacitor we confirm that the earth system can produce such large multidecadal timescale fluctuations in pco2 through simulating an artificial ocean flushing event with the genie earth system model we suggest that sharp transitions of pco2 may have remained undetected so far in ice cores due to inter firn gas exchange and time averaging the stomatal proxy record is a powerful complement to the ice core records for the study of rapid climate change

massive dissociation of gas hydrate during a jurassic oceanic anoxic event in the jurassic period the early toarcian oceanic anoxic event about 183 million years ago is associated with exceptionally high rates of organic carbon burial high palaeotemperatures and significant mass extinction heavy carbon isotope compositions in rocks and fossils of this age have been linked to the global burial of organic carbon which is isotopically light in contrast examples of light carbon isotope values from marine organic matter of early toarcian age have been explained principally in terms of localized upwelling of bottom water enriched in 12c versus 13c refs 1 2 5 6 here however we report carbon isotope analyses of fossil wood which demonstrate that isotopically light carbon dominated all the upper oceanic biospheric and atmospheric carbon reservoirs and that this occurred despite the enhanced burial of organic carbon we propose that as has been suggested for the late palaeocene thermal maximum some 55 million years ago the observed patterns were produced by voluminous and extremely rapid release of methane from gas hydrate contained in marine continental margin sediments

geochemical effects of petroleum migration and expulsion from toarcian source rocks in the hils syncline area nw germany for mature oil prone source rocks of toarcian age in the hils syncline area nw germany the geochemical effects of primary migration of petroleum are shown expulsion has occurred at high efficiencies primarily via a network of macro and micro fractures the effects of this fracture controlled expulsion with respect to gross and molecular composition of c15 soluble organic matter are documented samples from fractured intervals have expelled total c15 soluble organic matter more efficiently than adjacent unfractured intervals a systematic comparison of samples taken at cm intervals away from macro fractures reveals compositional gradients which are interpreted to reflect preferential depletion of saturated and aromatic hydrocarbons from the source rock shale into the fractures extracts of shale samples directly at fracture walls are enriched in nso compounds and highly polar asphaltene like fractions the composition of residual petroleum fluids extracted from the fracture fill materials is variable in some cases there is a close match with that of the shale at some distance away from the fractures in other cases there is geochemical evidence to suggest that petroleum fluids were chemically altered during lateral flow along the fractures based on available geological and geochemical evidence a conceptual model is proposed to explain fracture development and fluid flow processes rapid heating by a nearby intrusive body at shallow depths when the toarcian sediments still contained about 15 20 pore water has played an important role overpressuring of aqueous pore fluids with abundant dissolved carbonate caused intense fracturing of the rich intervals in the mature toarcian sections finally the closely interdependent relationships between petroleum generation and petroleum migration processes are documented especially the evolution of these relationships with maturity progress from immature 0 48 rm to mature 0 68 and 0 88 rm and overmature 1 45 rm stages is shown for example in the maturity interval from 0 68 to 0 88 rm most of the measured shale compaction and porosity decrease is achieved by expulsion of petroleum for some samples there is an inverse relationship between kerogen quality and extractable hydrocarbon yields suggesting that expulsion efficiencies were higher from the better quality intervals because the petroleum achieved higher saturations and hence higher relative permeabilities

the timing of paleoenvironmental change and cause and effect relationships during the early jurassic mass extinction in europe the early jurassic marine mass extinction is one of several crises thought to coincide with anoxia transgression and warming caused by catastrophic release of gas hydrates however high resolution study of expanded sections in yorkshire england reveal that only the first of these factors is truly coincidental with extinction the well known transgression and large negative carbon isotope perturbation attributed to massive release of methane from gas hydrates occur after these events the anoxic event is developed diachronously in the european area with anoxia developing and fading away earlier in the mediterranean region compared with the nw european record however for a brief interval in the mid semicelatum subzone anoxia was simultaneously developed throughout the european region and it is this time that is marked by extinction of both benthic and pelagic marine fossils the sea level curve is also more complex than hitherto assumed with a minor regression occurring late in the semicelatum subzone shortly after the extinction the toarcian crisis occurred during a phase of global warming but the postulated release of methane from gas hydrates is too late to be implicated in the extinction mechanism as indeed is a recently reported cooling event from within the warming trend

petroleum geochemistry of the kimmeridge clay of onshore southern and eastern england abstract the kimmeridge clay is considered a major oil source rock for the north sea hydrocarbon province the formation is also developed onshore in an organic rich mudstone facies this paper examines the possibility of onshore oil generation from the kimmeridge clay geochemically onshore basin margin sediments contain rich potential source horizons with mainly type l type ll oil prone kerogen but are immature some deeper cleveland basin sediments have reached marginal maturity burial history reconstruction suggests significant formation palaeoburial depths in central areas of the cleveland and wessex basins computed vitrinite isoreflectance contours show the wealden and isle of wight kimmeridge clay to be thermally mature basin modelling suggests an early palaeogene onset of oil generation in parts of the cleveland basin while maximum oil generation could have been reached by the formation base in the isle of wight area during the late cretaceous although basin subsidence ceased in the neogene in the weald and isle of wight where the formation is still deeply buried oil generation probably continued for some time during uplift thus significant quantities of oil could have been generated whether or not this oil is present today however would depend on the correct timing of suitable migration and trap structures

paleomagnetic data from the caborca terrane mexico implications for cordilleran tectonics and the mojave sonora megashear hypothesis two ancient magnetizations have been isolated in rocks of the caborca terrane northwest mexico the characteristic magnetizations of neoproterozoic and paleozoic miogeoclinal shelf strata arc derived lower jurassic marine strata and jurassic volcanic and volcaniclastic rocks are of dual polarity and east northeast declination or south south west and shallow inclination magnetizations in neoproterozoic and paleozoic miogeoclinal strata are interpreted as secondary j and to be of similar age to those observed in lower and middle jurassic rocks remanence acquisition is bracketed between about 190 and 160 ma the overall mean d 15 0 i 8 5 n 38 sites six localities k 19 1 95 5 5 suggests a moderate to large clockwise rotation of 12 to 50 depending on reference direction assumed of the caborca terrane and rocks of the sonoran segment of the cordilleran volcanic arc with respect to the north america craton when compared with expected inclinations observed values are not anomalously steep arguing against statistically significant southward latitudinal displacement of the caborca block after remanence acquisition late cretaceous intrusions yield primary dual polarity steep inclination k magnetizations d 341 4 i 52 3 n 10 sites five localities k 38 3 95 7 9 and have locally remagnetized neoproterozoic and jurassic strata when present secondary k magnetizations in neoproterozoic strata are of higher coercivity and higher unblocking temperature than the characteristic j magnetization importantly the regional internal consistency of data for late cretaceous intrusions suggests that effects of tertiary tilt or rotation about a vertical axis over the broad region sampled 5000 km2 are not substantial late cretaceous primary k magnetizations and secondary k magnetizations yield a combined mean of d 348 1 i 50 7 n 10 localities 47 sites k 53 5 95 6 7 indicating at most small 10 clockwise rotation of the caborca region with respect to the craton permissible post late cretaceous latitudinal displacement is near or below the detection limit of paleomagnetism 300 km limited data from lower cretaceous strata of the bisbee group d 339 9 i 47 9 n 4 sites suggest that the modest clockwise rotations inferred on the basis of j magnetizations in jurassic and older strata occurred in jurassic time together the lack of evidence for southward displacement yet evidence for statistically significant clockwise rotation and the overall similarity of jurassic magnetizations in the cordilleran arc with those of the caborca block despite the fact that some of them are clearly secondary are not consistent with the mojave sonora megashear hypothesis of late jurassic left lateral strike slip motion of the crust of northern mexico

permeability porosity transforms from small sandstone fragments numerical simulation of laboratory experiments on rocks or digital rock physics is an emerging field that may eventually benefit the petroleum industry for numerical experimentation to find its way into the mainstream it must be practical and easily repeatable i e implemented on standard hardware and in real time this condition reduces the size of a digital sample to just a few grains across also small physical fragments of rock such as cuttings may be the only material available to produce digital images will the results be meaningful for a larger rock volume to address this question we use a number of natural and artificial medium to high porosity well sorted sandstones the 3d microtomography volumes are obtained from each physical sample then analogous to making thin sections of drill cuttings we select a large number of small 2d slices from a 3d scan as a result a single physical sample produces hundreds of 2d virtual drill cuttings images corresponding 3d pore space realizati

triassic plutonism in southern california southward younging of arc initiation along a truncated continental margin earliest cordilleran magnatism in the southwestern united states is recorded by a belt of triassic plutons that inme protemzoic basemint of the mojave crustal province and its cratona miogeoclinal cover the belt extends from the western mojave desert through the trausverse ranges to the colorado river trough triassic plutons are predominantly alkali calcic fe and sr mriched quartz mzrdior tes and monzonites the northern part of the belt is comlx sed of two older plutonic mites 241 231 ma which are high k to shoshonitic the southern part of the belt is a younger 218 213 ma sodic alkalic suite the plutonic record in southern california suggests a short lived southward younging continental margin arc sang for eraplacement of triassic plutons sulim on a continental margin modified by s mistral tranqform faulting triassic plutonism in this region was followed by a magmatic lull prior to the onset of voluminous middle to late jurassic cordilleran arc magmatism

experimental study of fluid transport processes in the matrix system of the european organic rich shales ii posidonia shale lower toarcian northern germany abstract a laboratory study has been conducted to investigate the transport of gases he ar ch 4 and water in the matrix of lower toarcian posidonia shale samples from three shallow boreholes in northern germany the maturity of the organic matter of the shale samples ranged between 0 53 and 1 45 vitrinite reflectance vr r the measurements were performed at effective stresses ranging between 6 and 37 mpa and a temperature of 45 c the effects of different controlling factors including permeating fluid maturity anisotropy moisture content and effective stress on the fluid conductivity were analyzed and discussed permeability coefficients measured perpendicular and parallel to bedding 3 10 22 to 9 7 10 17 m 2 were within the range previously reported for other shales and mudstones they exhibited a strong dependence on permeating fluid maturity anisotropy moisture content and effective stress the permeability coefficients measured with helium as permeate were consistently higher up to two times than those measured with argon and methane permeability coefficients measured with water were up to three orders of magnitude lower than klinkenberg corrected gas permeability coefficients measured with helium and methane under similar experimental conditions among the samples studied the lowest porosity and permeability coefficients were measured on samples of intermediate thermal maturity 0 88 vr r oil window permeability coefficients he ch 4 measured parallel to bedding were up to more than one order of magnitude higher than those measured perpendicular to bedding permeability coefficients measured with he and ch 4 on a dry sample were up to two times higher than those measured on a sample with the as received moisture content all samples showed a nonlinear reduction in permeability parallel to bedding with increasing effective stress 6 37 mpa the permeability anisotropy and stress dependence of permeability were controlled by the mineralogy

rapid late glacial atmospheric co2 changes reconstructed from the stomatal density record of fossil leaves the younger dryas stadial 11 000 10 000 yr bp was an abrupt return to a glacial climate during the termination of the last glaciation we have reconstructed atmospheric co2 concentrations from a high resolution sequence of fossil salix herbacea leaves through this climatic oscillation from krakenes western norway using the relationship between leaf stomatal density and atmospheric co2 concentration high allerod co2 values median 273 ppmv decreased rapidly during 130 200 14c years of the late allerod to ca 210 ppmv at the start of the younger dryas they then increased steadily through the younger dryas reaching typical interglacial values once more ca 275 ppmv in the holocene the rapid late allerod decrease in co2 concentration preceded the younger dryas temperature drop possibly by several decades this striking pattern of changes has not so far been recorded unambiguously in temporally coarse measurements of atmospheric co2 from ice cores our observed late glacial co2 changes have implications for global modelling of the ocean atmosphere biosphere over the last glacial interglacial transition

co 2 diffusion in polar ice observations from naturally formed co 2 spikes in the siple dome antarctica ice core this is the publisher s final pdf the published article is copyrighted by the international glaciological society and can be found at http www igsoc org journal

geological analysis of the silver lake marsokhod field test from ground truth sampling and mapping we compare the results of the observations and conclusions obtained from a remote science team and field geologists during the 1999 marsokhod silver lake field experiment this comparison is used to determine methods that enhance the ability of a remote team using a rover to determine the geology and paleoclimate of a landing site analogous to sites that may be encountered during the mars surveyor program the mobility of the field geologists and their ability to rapidly gain visual and physical data from the field site give an immediate confidence to their interpretation of the geology the finite time of teleoperation and the initial decisions and mechanical problems that caused the rover to linger and collect data in a small area of the test site for the first 5 days of the test limited the ability of the remote science team to gain a similar confidence nevertheless by appropriate use of orbital and descent images as well as the rover s science payload the remote science team interpreted the present and former climates the geology and geological history and present day biology relatively accurately the few erroneous interpretations by the remote team resulted in part from biases brought to the test about the nature of the geology that was likely to be encountered data quality and variety also impacted the quality of the geological interpretations significant misinterpretations in the remotely determined geology resulted from the lack of detail in the optical imagery a less than optimal understanding of the site s topography and misinterpretation of some infrared data all in all this field test showed that the geology paleoclimate and biology of a site can be assessed to a reasonable level of confidence using a remotely controlled vehicle it also showed that it is both feasible and desirable for a distributed science team to participate in long science missions from home institutions as long as data flows efficiently to and from these institutions

evolution of petrophysical properties of oil shales during high temperature compaction tests implications for petroleum expulsion abstract the transport properties of permian to miocene oil shales torbanite posidonia messel himmetoglu and condor were studied using petrophysical and geochemical techniques the aims of this study were to assess permeability of oil shales evaluate the evolution of porosity specific surface area and intergranular permeability during high temperature compaction tests and to verify the suitability of intergranular permeability for petroleum expulsion measured permeability coefficients for two samples were 0 72 10 21 m for the eocene messel shale and 2 63 10 21 m for the lower jurassic posidonia shale from s germany respectively bet specific surface areas of the original samples ranged from 0 7 to 10 6 m g and decreased after compaction to values from 0 3 to 3 7 m g initial porosity values ranged from 7 6 to 20 1 for pre deformation and from 9 99 to 20 7 for post deformation samples porosity increased during the high temperature compaction experiments due to petroleum generation and expulsion permeability coefficients estimated using the kozeny carman equation varied from 6 97 10 24 m to 5 22 10 21 m for pre deformation and from 0 2 10 21 m to 4 8 10 21 m for post deformation samples reflecting the evolution of their porosity and bet specific surface areas measured and calculated permeability were similar for the messel shale whereas calculated permeability was two orders of magnitude lower for the posidonia shale from s germany petroleum expulsion efficiencies under the experimental conditions ranged from 38 6 for the torbanite to 96 2 for the posidonia shale from s germany they showed strong positive correlation with the petroleum generation index r 0 91 and poor correlations with porosity r 0 46 average pore throat diameters r 0 22 and compaction r 0 02 estimated minimum pore system saturations for petroleum expulsion during the experiments were 12 for the torbanite and 30 for the posidonia shale from n germany pore system saturation determines whether expulsion occurs mainly through matrix or fracture permeability for samples with saturation levels above 20 fracture permeability dominated during the experiments evidence based on the measured permeability coefficients expulsion flow rates consideration of capillary displacement during generation related pore invasion and the existence of transport porosity suggests that fracture permeability is the principal avenue of petroleum expulsion from source rocks this conclusion is supported by microscopic observations

australian dust storms in 2002 2003 and their impact on southern ocean biogeochemistry during late 2002 and early 2003 southern australia was in the grip of drought and experienced one of its most active dust storm seasons in the last 40 years with large dust plumes frequently advected over the adjacent southern ocean we use meteorological records of dust activity satellite ocean colour and aerosol optical depth data and dust transport modeling to investigate the transport and deposition of mineral dust from australia over adjacent ocean regions and to correlate it with biological response in phytoplankton standing stock as measured by chlorophyll a concentration in five degree latitude bands from 40 60 s seasonal maxima in mean surface chlorophyll a of 0 5 mg m 3 were not achieved until late jan 2003 or during february in the more southerly bands which when compared with a 9 year satellite mean climatology suggests the phenology of the bloom in 2002 03 was atypical contemporaneous field data on co2 fugacity collected on transects between tasmania and antarctica show that significant atmospheric co2 drawdown occurred as far south as 60 s during february 2003 our results provide strong evidence for a large scale natural dust fertilization event in the australian sector of the southern ocean and highlight the importance of dust derived nutrients in the marine carbon cycle of the southern ocean

response to comment on synchronous records of pco2 and δ14c suggest rapid ocean derived pco2 fluctuations at the onset of younger dryas steinthorsdottir et al 2014 quaternary science reviews 99 84 96 response to comment on synchronous records of pco 2 and delta c 14 suggest rapid ocean derived pco 2 fluctuations at the onset of younger dryas steinthorsdottir et al 2014 quaternary science reviews 99 84 96

bib sem study of the pore space morphology in early mature posidonia shale from the hils area germany abstract this contribution reports on the study of the pore space morphology in two early mature vr r 0 59 and 0 61 samples of posidonia shale from the hils syncline in germany using broad ion beam bib polishing and high resolution scanning electron microscopy sem this allows imaging pores with resolution down to 10 nm in equivalent diameter d eq and quantitative estimation of porosity using a combination of bse and se detectors and semi automatic segmentation of the gigapixel images the representative elementary area of the samples on the scale of a few mm is inferred to be about 140 140 m 2 pore morphologies and pore sizes are clearly related to the mineral fabric with large differences very large typically several microns pores with internal faceted crystal morphology in recrystallized calcite clasts and smaller pores d eq cf schizosphaerella nanofossils typically 200 nm pores are less common in organic material and in pyrite aggregates pore characteristics are very similar for both samples and porosity resolvable by bib sem is 2 75 and 2 74 pore size distribution can be described by a power law with an exponent about 2 0 and 2 2 respectively for the pore population excluding the fossils pores in the carbonate fossils show dual power law distribution with power law exponents of about 1 and 3 by extrapolating the power law distribution for each sample total porosity is estimated to be 4 8 0 9 1 7 and 6 5 2 7 7 2 respectively this estimate can be compared with 3 4 3 7 and 3 3 3 6 as measured by mercury injection porosimetry we interpret this difference to reflect the unconnected for mercury part of the porosity comparison of imaged pores and mercury injection porosimetry suggest a very high pore body to pore throat ratio this results in a pore model where large pores represented mainly by pores in fossils and calcite grains are connected via a low porous and low permeable clay rich matrix with pore throats below 10 nm in both samples

ground penetrating radar as a tool for probing the shallow subsurface of mars 1 design and testing of an impulse ground penetrating radar gpr for possible rover deployment on mars in 2009 is well underway the gpr has mass power volume and data rate targets of 0 5 kg 3 w peak 3400 cm3 and 0 3 mb d and will possess easily modified bistatic high frequency e g 500 600 mhz and monostatic rat tail e g 100 mhz antennas the gpr should be capable of measuring in situ radar properties on mars to depths of up to 10 20 m thereby helping to constrain near surface geology and structure initial gpr tests at the site of the 2001 fido rover field trials near cronese lake california confirm the value of the instrument in defining local geologic setting and in providing context for data collected using other rover science payload elements a rover deployed gpr may enable three dimensional mapping of local stratigraphy which in turn can assist in evaluating the history of aqueous activity and the accessibility of near surface water