diviner lunar radiometer observations of cold traps in the moon s south polar region diviner lunar radiometer experiment surface temperature maps reveal the existence of widespread surface and near surface cryogenic regions that extend beyond the boundaries of persistent shadow the lunar crater observation and sensing satellite lcross struck one of the coldest of these regions where subsurface temperatures are estimated to be 38 kelvin large areas of the lunar polar regions are currently cold enough to cold trap water ice as well as a range of both more volatile and less volatile species the diverse mixture of water and high volatility compounds detected in the lcross ejecta plume is strong evidence for the impact delivery and cold trapping of volatiles derived from primitive outer solar system bodies

characterization of geomorphological features of lunar surface using chandrayaan 1 mini sar and lro mini rf data abstract the lunar surface comprises complex geomorphological features which have been formed by the conjunction of processes namely impact cratering and volcanism geological features on the lunar surface can be bifurcated into two main areas named maria region and the highland region taurus littrow valley which was the apollo 17 mission landing site consisting of unique geomorphological characteristics by having a sample size of both lunar maria and highland regions the dielectric constant is a parameter that gives an approximate distribution of the constituent material of the target area it is a complex quantity which indicates a periodic variation of the electric field the real part of dielectric constant indicates stored energy and the imaginary part indicates dielectric loss factor or the loss of the electric field in the medium due to continuous varying electric field planetary surfaces for which determining dielectric constant is an important analysis for most of the space missions ground measurement is not feasible this work includes the machine learning based modeling of dielectric constant for the apollo 17 landing site the taurus littrow valley based on the surface roughness of the study area two models gaussian and exponential have been implemented and compared for the modeled output of the dielectric constant values the modeling approaches for dielectric characterization of the lunar surface were implemented on nasa s lro mini rf sar data and mini sar hybrid pol data of isro s chandrayaan 1 mission the coefficient of determination r2 and the root mean square error rmse of the theoretical gaussian model was 0 995 0 042 and the exponential model was 0 948 0 1349 respectively when compared with the already calculated values of dielectric constant from apollo 17 return samples and literature survey the gaussian model gives a better variation gaussian model was further applied to the lunar north pole crater namely hermite a crater whose distinctive geomorphological characteristics and location being lunar north pole region makes it one of the coldest places in the solar system and a prominent location of water ice deposits

global distribution of large lunar craters implications for resurfacing and impactor populations by using high resolution altimetric measurements of the moon we produced a catalog of all impact craters 20 kilometers in diameter on the lunar surface and analyzed their distribution and population characteristics the most densely cratered portion of the highlands reached a state of saturation equilibrium large impact events such as orientale basin locally modified the prebasin crater population to 2 basin radii from the basin center basins such as imbrium orientale and nectaris which are important stratigraphic markers in lunar history are temporally distinguishable on the basis of crater statistics the characteristics of pre and postmare crater populations support the hypothesis that there were two populations of impactors in early solar system history and that the transition occurred near the time of the orientale basin event

reappraisal of hydrocarbon biomarkers in archean rocks hopanes and steranes found in archean rocks have been presented as key evidence supporting the early rise of oxygenic photosynthesis and eukaryotes but the syngeneity of these hydrocarbon biomarkers is controversial to resolve this debate we performed a multilaboratory study of new cores from the pilbara craton australia that were drilled and sampled using unprecedented hydrocarbon clean protocols hopanes and steranes in rock extracts and hydropyrolysates from these new cores were typically at or below our femtogram detection limit but when they were detectable they had total hopane 37 9 pg per gram of rock and total sterane 32 9 pg per gram of rock concentrations comparable to those measured in blanks and negative control samples in contrast hopanes and steranes measured in the exteriors of conventionally drilled and curated rocks of stratigraphic equivalence reach concentrations of 389 5 pg per gram of rock and 1 039 pg per gram of rock respectively polycyclic aromatic hydrocarbons and diamondoids which exceed blank concentrations exhibit individual concentrations up to 80 ng per gram of rock in rock extracts and up to 1 000 ng per gram of rock in hydropyrolysates from the ultraclean cores these results demonstrate that previously studied archean samples host mixtures of biomarker contaminants and indigenous overmature hydrocarbons therefore existing lipid biomarker evidence cannot be invoked to support the emergence of oxygenic photosynthesis and eukaryotes by 2 7 billion years ago although suitable proterozoic rocks exist no currently known archean strata lie within the appropriate thermal maturity window for syngenetic hydrocarbon biomarker preservation so future exploration for archean biomarkers should screen for rocks with milder thermal histories

molecular memory effects recording the accumulation history of petroleum reservoirs a case study of the heidrun field offshore norway abstract the immobile portion of the oil occupying the pore space of reservoir sandstones which is mostly represented by visible impregnations is shown by the present study to contain geochemical signals that record their filling history the clue to unravelling these signals is sequential extraction of such impregnations of residual oil by a high pressure solvent flow through cell in which the solvent percolates through the intact and primary pore system of the rock sample gas chromatography mass spectroscopy gc ms analysis of residual oils extracted from samples of certain reservoir sandstones within the heidrun field offshore norway reveal significant contrasts in the chemical maturity of the first and the last fractions recovered as high as 0 69 versus 0 50 for the mpi 1 ratio corresponding to 0 79 versus 0 67 rc the hypothesis is proposed that by using this extraction technique oil impregnations from different portions of the pore system i e from large versus small pores are obtained separately this interpretation is especially supported by the regular occurrence of reservoir sandstones in which the residual oil exhibits maturity contrasts between those fractions extracted from large and small pores of the same rock within the heidrun field the distribution of reservoir sandstones with such maturity contrasts is strictly controlled by their position in the oil column and the location of their fault compartment these contrasts are interpreted to reflect the maturity levels of end members of the petroleum charges which have filled this trap during an extended period of geological time reservoir sandstone samples containing such end member charges are limited to the uppermost portion of the oil column lower in the oil column the pore system of all reservoirs contains oil impregnations of a uniform maturity level regardless of their pore size origin this distribution is believed to indicate an early stage of the accumulation history of the heidrun field characterised by the formation of a palaeo oil water contact well above the present one moreover the four fault compartments studied each controlled by bordering faults with different sealing capacities were not filled during the same stages of the accumulation history in summary the present study has shown that oil impregnations depending on their location within the pore system of individual reservoir sandstones can retain molecular memory effects which in turn allow the accumulation history of petroleum fields to be reconstructed

arecibo radar mapping of the lunar poles a search for ice deposits the arecibo 12 6 centimeter wavelength radar system was used to image the polar regions of the moon at a resolution of 125 meters in a search for ice deposits in areas of possible permanent shadow from the sun no areas greater than 1 square kilometer were found with high radar backscatter cross sections and high circular polarization ratios properties suggestive of the presence of ice a number of areas smaller than 1 square kilometer were found with these properties but optical images from spacecraft missions have shown some of these features to be in sunlight arecibo radar images of sinus iridum at latitude 47 n also showed a number of small features with similar properties the coincidence of some of these features with the radar facing slopes of craters and their presence in sunlit areas suggests that very rough surfaces rather than ice deposits are responsible for their unusual radar properties

unravelling the mystery of lunar anomalous craters using radar and infrared observations in miniature radio frequency mini rf radar images anomalous craters are those having a high circular polarization ratio cpr in their interior but not exterior to their rims previous studies found that most cpr anomalous craters contain permanently shadowed regions psrs and that their population is overabundant in the polar regions however there is considerable controversy in the interpretation of these signals both water ice deposits and rocks surface roughness have been proposed as the source of the elevated cpr values to resolve this controversy we have systematically analyzed 4000 impact craters with diameters between 2 5 and 24 km in the mini rf radar image and diviner rock abundance ra map we first constructed two controlled orthorectified global mosaics using 6818 tracks of mini rf raw data and then analyzed the correlations between radar cpr and surface slope rock abundance and depth diameter ratios of impact craters our results show that cpr anomalous craters are distributed relatively uniformly across the lunar surface with no apparent difference in cpr between the polar potentially icy and non polar not icy craters most cpr anomalous craters are relatively young with a large depth diameter ratio and they actually represent an intermediate stage of crater evolution comparison with a two component radar scattering model suggests that rocks and surface roughness are major contributors to the observed cpr values using craters of 4 7 22 km in diameter with known ages we find that craters spend up to 120 ma with a high exterior ra and 3 ga in the cpr anomalous phase

a reappraisal of kerogen formation abstract comparative microscopical and chemical studies of recognizable entities in kerogen and their extant counterparts suggest a new and simple mechanism of kerogen formation which clarifies the interrelationships between extant biomass kerogen and fossil fuels

constraints on the magnitude and patterns of ocean cooling at the last glacial maximum observation based reconstructions of sea surface temperature from relatively stable periods in the past such as the last glacial maximum represent an important means of constraining climate sensitivity and evaluating model simulations1 the first quantitative global reconstruction of sea surface temperatures during the last glacial maximum was developed by the climate long range investigation mapping and prediction climap project in the 1970s and 1980s refs 2 3 since that time several shortcomings of that earlier effort have become apparent4 here we present an updated synthesis of sea surface temperatures during the last glacial maximum rigorously defined as the period between 23 and 19 thousand years before present from the multiproxy approach for the reconstruction of the glacial ocean surface margo project5 we integrate microfossil and geochemical reconstructions of surface temperatures and include assessments of the reliability of individual records our reconstruction reveals the presence of large longitudinal gradients in sea surface temperature in all of the ocean basins in contrast to the simulations of the last glacial maximum climate available at present6 7

lunar surface rock abundance and regolith fines temperatures derived from lro diviner radiometer data 1 surface temperatures derived from thermal infrared measurements provide a means of understanding the physical properties of the lunar surface the contrasting thermophysical properties between rocks and regolith fines cause multiple temperatures to be present within the field of view of nighttime multispectral data returned from the lunar reconnaissance orbiter lro diviner radiometer between 60 n s latitudes regolith temperatures are influenced by the presence of rocks in addition to factors such as the thermophysical properties of the regolith fines latitude and local slopes and radiative heating from adjacent crater walls preliminary comparisons of derived rock concentrations with lro camera images show both qualitative and quantitative agreement although comparisons of derived rock concentrations with circular polarization ratio radar data sets display general similarities there are clear differences between the two data sets in the relative magnitude and areal extent of rocky signatures several surface units can be distinguished based on their regolith temperature and rock concentration values and distributions including maria and highlands surfaces rocky impact craters rilles and wrinkle ridges dark mantled deposits and isolated cold surfaces rock concentrations are correlated with crater age and rocks are only preserved on the youngest surfaces or where steep slopes occur and mass wasting prevents mantling with fines the presence of rocky surfaces excavated by young impacts allows for the estimation of minimum regolith thickness from the size of the impact the derived rock concentrations confirm the presence of thicker regolith cover in the highlands and in locations of radar dark haloes

residual oil as a tool in migration and filling history analysis of petroleum reservoirs ghazal field saudi arabia abstract stepwise extraction and molecular analysis of non recoverable oil from intact reservoir core plugs is used to provide constraints on the accumulation history of petroleum in the permo carboniferous unayzah reservoirs at the ghazal field saudi arabia when integrated with existing tools such as oil geochemistry gas geochemistry stable carbon isotopes fluid inclusions and thermal modeling the sequential extraction approach helped decode a previously unrecognized component of the hydrocarbon accumulation history in particular it indicates that the region received early petroleum charges that were less mature than currently produced light oil and gas condensates possibly from the prolific early silurian qusaiba shale source rock and other sources this has significant implications for prospecting for additional oil particularly in the north northwest of the ghazal region where paleo oil accumulations may have been displaced or spilled the lower portion of the unayzah reservoir unayzah c remained water wet during early filling of the upper reservoir unit unayzah a and appears to have been filled only by a late oil charge anomalous molecular and carbon isotopic behavior of residual oil extracts from the uppermost segment of the unayzah reservoir where the free oil first of the sequential extracts is less mature 0 95 rc and isotopically lighter 13c 31 15 than the adsorbed oil last sequential extract 1 05 rc 13c 29 65 suggests a late oil contribution or bitumen contamination from the overlying khuff formation

geochemical application of sterane and triterpane biological marker compounds in the linyi basin abstract the saturated and aromatic hydrocarbon fractions of 41 crude oils and 53 rock extracts from the linyi basin people s republic of china were investigated for their biological marker composition by combined gas chromatography mass spectrometry hopane and sterane carbon number distributions were found to be useful for oil source rock correlation whereas sterane and hopane isomerization and steroid aromatization were used for maturity assessment of both oils and sediments in the immature range the isomer distributions of 17 h trisnorhopane 17 h trisnorphopane and 18 h trisnorneohopane followed a systematic trend explicable on the basis of the relative stabilities of these structures the major source rock is the es 3 member of the shahejie formation late oligocene petroleum generation becomes significant at 2500 m 95 c oil expulsion from source rocks occurs between about 3200 and 4200 m 120 150 c

sulfurized carbohydrates an important sedimentary sink for organic carbon abstract in contrast to the general belief that carbohydrate carbon ccho is preferentially degraded and is not extensively preserved in the sedimentary record it is shown here that ccho forms a large fraction of the organic matter om of the total organic carbon toc rich upper jurassic kimmeridge clay formation as a result of early diagenetic sulfurization a previously unrecognized pathway of om preservation this is evident from both changes in the molecular composition of the insoluble om and from 13ctoc shifts of 6 with varying ccho contents furthermore experiments simulating the natural sulfurization of the ccho rich alga phaeocystis spp demonstrated that sulfurization can indeed lead to a substantial preservation of ccho with a molecular fingerprint identical to that of the kimmeridge clay and many other recent and ancient marine om rich sediments these results imply that preservation of ccho can exert a fundamental control on 13ctoc in om rich sediments complicating the interpretation of 13ctoc records with regard to estimating terrestrial versus aquatic om fractions reconstruction of past atmospheric co2 levels and global carbon budget models

millimeter scale concentration gradients of hydrocarbons in archean shales live oil escape or fingerprint of contamination abstract archean shales from the pilbara in western australia contain biomarkers that have been interpreted as evidence for the existence of cyanobacteria and eukaryotes 2 7 billion years ga ago with far reaching implications for the evolution of earth s early biosphere to re evaluate the provenance of the biomarkers this study determined the spatial distribution of hydrocarbons in the original drill core material rock samples were cut into millimeter thick slices and the molecular content of each slice was analyzed in core from the hamersley group 2 5 ga c alkanes had gradually increasing concentrations from the surfaces to the center of the rock while the abundance of steranes hopanes and c 15 alkanes decreased with distance from the outer surfaces in samples from the fortescue group 2 7 ga hydrocarbons were overwhelmingly concentrated on rock surfaces two mechanisms are proposed that may have caused the inhomogeneous distribution diffusion of petroleum products into the rock contamination model and leaching of indigenous hydrocarbons out of host shales driven by pressure release after drilling live oil effect to test these models the hydrocarbon distributions in the archean shales are compared with artificially contaminated rocks as well as younger mudstones where leaching of live oil had been observed the results show that chromatographic phenomena associated with live oil escape and contaminant diffusion have strong effects on molecular ratios and maturity parameters potentially with broad implications for oil source rock correlation studies and paleoenvironmental interpretations for the archean shales the live oil effect is consistent with some of the observed patterns but only the contamination model fully explains the complex chromatographic fingerprints therefore the biomarkers in the pilbara samples have an anthropogenic origin and previous conclusions about the origin of eukaryotes and oxygenic photosynthesis based on these samples are not valid however the study also identified indigenous molecules the spatial distribution of particular aromatic hydrocarbons suggests they are syngenetic although devoid of biological information these aromatics now represent the oldest known clearly indigenous terrestrial liquid hydrocarbons

spatial distribution of lunar polar hydrogen deposits after kaguya selene 1 although controversial in its physical form there is mounting evidence of hydrogen enhancements at the lunar poles the permanently shadowed locales are potential sites for significant concentrations of cold trapped volatiles including water ice we derive maps of the lunar hydrogen distribution near the poles by applying a pixon image reconstruction algorithm to the lunar prospector epithermal neutron data coupled with a new map of cold trap locations derived from the kaguya selene altimetry measurements the results presented in this article require the hydrogen to be concentrated into cold traps

heterogeneity of free and occluded bitumen in a natural maturity sequence from oligocene lake enspel abstract sedimentation in oligocene lake enspel was rapidly terminated by a basaltic lava flow this introduced a preservational barrier while imparting a natural flash pyrolysis during which the organic matter in underlying stratigraphic units was subjected to rapid thermal maturation resulting in hydrocarbon generation samples from these strata exhibit a steep maturity gradient 0 25 1 07 optical vitrinite reflectance or ro over uniform organofacies this offers the opportunity to investigate bitumen generation during rapid thermal maturation mechanistically in particular the nature of bitumen 2 occluded bitumen which is only recoverable after the digestion of the mineral matrix and was frequently dismissed as an artifact of incomplete extraction elaborate sequential extraction of the contact metamorphic sequence of oil shales at enspel revealed systematic changes in bitumen composition these trend progressively towards those of occluded bitumen which exhibits a systematically elevated thermal maturity a higher degree of catalytic biomarker rearrangement and the conspicuous absence of molecular signatures from vascular plants that are present in the free bitumen one plausible explanation involves a contribution of allochthonous clay adsorbed organic matter to bitumen 2 this could represent a mixture of older reworked bitumen and an early diagenetic snapshot of clay adsorbed organic matter alternatively a close association of early generated bitumen with clay minerals may have led to enhanced isomerization and catalytically influenced uniformization of alkane signatures deviations from the expected relationships between various thermal maturity parameters suggest variable dependence on the time pressure temperature pathway i e metamorphic facies the maturation of organic matter likely behaves differently under a contact metamorphic regime or during rapid subsidence and exhumation as compared to slow maturation during regional subsidence our data also suggest that geologically brief shallow intrusive or extrusive magmatism might not be as destructive to the sedimentary hydrocarbon inventory as hitherto thought this study draws attention to the small scale compositional heterogeneity of bitumen that can be studied using sequential extraction methods more importantly it suggests that occluded bitumen could potentially harbor information on organic matter that pre dates in situ primary productivity and may be derived from allochthonous biomass and detrital input

modeling polarimetric radar scattering from the lunar surface study on the effect of physical properties of the regolith layer 1 a theoretical model for radar scattering from the lunar regolith using the vector radiative transfer theory for random media has been developed in order to aid in the interpretation of mini sar data from the chandrayaan 1 and lunar reconnaissance orbiter missions the lunar regolith is represented as a homogeneous fine grained layer with rough upper and lower parallel interfaces that possesses embedded inclusions with a different dielectric constant our model considers five scattering mechanisms in the regolith layer diffuse scattering from both the surface and subsurface volume scattering from buried inclusions and the interactions of scattering between buried inclusions and the rough interfaces both the lunar surface and subsurface multiple scattering between buried inclusions and coherent backscatter opposite effect are not considered in the current model the modeled radar scattering coefficients are validated using numerical finite difference time domain simulations and are compared with incident angle averaged earth based radar observations of the moon both polarized and depolarized radar backscattering coefficients and the circular polarization ratio cpr are calculated as a function of incidence angle regolith thickness surface and subsurface roughness surface slope abundance and shape of buried rocks and the feo tio2 content of the regolith simulation results show that the polarized opposite sense radar echo strength at s and x bands is mostly dominated by scattering from the rough surface and buried rocks while the depolarized same sense radar echo strength is dominated by scattering from buried rocks or ice inclusions finally to explore the expected polarimetric signature of ice in the polar permanently shadowed areas four parametric regolith models are considered and the possibility of detecting diffuse ice inclusions by the cpr is addressed our study suggests that detection of ice inclusions at the lunar poles using solely the cpr will be difficult given the small dielectric contrast between the regolith and ice

impact of sea ice variability on the oxygen isotope content of seawater under glacial and interglacial conditions records of temporal variability in the oxygen isotopic composition of biogenic carbonates 18oc from ocean sediment cores inform our understanding of past continental ice volume and ocean temperatures interpretation of 18ocvariability typically neglects changes due to factors other than ice volume and temperature here we investigate whether glacial interglacial changes in sea ice which fractionates seawater during its formation could shift the isotopic value of seawater in the deep ocean affecting benthic foraminiferal 18oc and thereby potentially impacting oxygen isotope based sea level reconstructions or in surface waters affecting planktic foraminiferal 18oc we simulate glacial and interglacial states with the isotope enabled university of victoria earth system climate model and perform a global analysis distinct patterns of sea ice production emerge for the glacial versus interglacial states we find no substantive shift in 18ow in model deep or bottom waters due to the simulated interglacial glacial sea ice variability small isotopic shifts due to sea ice variability are concentrated in the model s surface waters of the northern hemisphere specifically in the labrador sea and northeastern north atlantic

dinocyst based reconstructions of sea ice cover concentration during the holocene in the arctic ocean the northern north atlantic ocean and its adjacent seas abstract sea ice cover extent expressed in terms of mean annual concentration was reconstructed from the application of the modern analogue technique to dinocyst assemblages the use of an updated database which includes 1492 sites and 66 taxa yields sea ice concentration estimates with an accuracy of 1 1 10 holocene reconstructions of sea ice cover were made from dinocyst counts in 35 cores of the northern north atlantic and arctic seas in the canadian arctic the results show high sea ice concentration 7 10 with little variations throughout the interval in contrast in arctic areas such as the chukchi sea and the barents sea the reconstructions show large amplitude variations of sea ice cover suggesting millennial type oscillations with a pacing almost opposite in western vs eastern arctic other records show tenuous changes with some regionalism either in trends or sea ice cover variability during the mid holocene and notably at 6 0 5 ka minimum sea ice concentration is recorded in the eastern fram strait northern baffin bay and labrador sea however this minimum cannot be extrapolated at the scale of the arctic and circum arctic the comparison of recent observations and reconstructions suggests larger variations in the arctic sea ice cover during the last decades than throughout the holocene

algal and bacterial hydrocarbons in particulate matter and interfacial sediment of the cariaco trench particulate matter samples 53 m size fractions and sediment from the sediment water interface were collected in the cariaco trench an anoxic marine basin on the continental shelf of venezuela and analyzed for hydrocarbons concentrations of hydrocarbons were highest 10 20 ng 1 in oxic surface waters 0 150 m and at the top of the anoxic zone 350 600 m and were low 3 4 ng l in the low oxygen zone above the oxic anoxic interface 150 250 m and anoxic bottom waters 600 1150 m branched c25 trienes and tetraenes dominated the hydrocarbon distributions in 53 m particles particle size and depth distributions of the hydrocarbons demonstrate the importance of algal hydrocarbons in surface waters coupled with increased abundances of bacterial hydrocarbons especially in the 53 m particles in the anoxic zone these observations illustrate the importance of oxic anoxic interfaces even in the oceanic water column as zones of intense microbial alteration of organic matter and as sources of some of the organic compounds found in sediments

the migration of volatiles on the surfaces of mercury and the moon radar observations of mercury have provided the startling discovery of the probable existence of substantial deposits of ices in permanently shaded polar regions butler et al 1993 harmon et al 1994 this has renewed the old argument about the existence of such deposits in the polar regions of the moon it is most likely necessary for volatiles to be able to migrate to the polar regions of these bodies in order to build up such deposits this paper presents the results of the extension of a monte carlo simulation of the migration of molecules on the surface of mercury by butler et al 1993 the results of the simulations show that for typical conditions on mercury 5 15 of all h 2 o which is placed randomly on the surface migrates to stable permanently shaded polar regions for the moon the numbers are 20 50 the numbers for the migration of co 2 are 2 for mercury and 13 for the moon these percentages are similar to those previously calculated and support the idea of ice deposits in the polar regions of both mercury and the moon

multiproxy approach for the reconstruction of the glacial ocean surface margo michal kucera antoni rosell mele ralph schneider claire waelbroeck mara weinelt department of geology royal holloway university of london egham tw20 0ex uk icrea and institute of environmental science and technology universitat autonoma de barcelona 08193 bellaterra catalonia spain departement de geologie et oceanographie umr5805 epoc cnrs universite de bordeaux1 33405 talence cedex france laboratoire des sciences du climat et de l environnement laboratoire mixte cnrs cea f 91198 gif sur yvette france institute for geosciences university of kiel olshausen strasse 40 d 24098 kiel germany

a novel sequential extraction system for whole core plug extraction in a solvent flow through cell application to extraction of residual petroleum from an intact pore system in secondary migration studies abstract the rapidly developing field of reservoir geochemistry and studies into secondary migration require new methods and techniques to characterise the composition of organic fluids obtained from reservoir rock samples ideally the composition of residual petroleums should be compared with the mineralogical and petrophysical properties from the same sample this requires a non destructive extraction procedure that keeps the rock in its natural state we have developed a flow through extraction system capable of efficiently extracting core plugs while preserving the pore system of the sample extractions can be performed sequentially to obtain various oil phases present in the pore system i e free or mobile oil can be obtained separately from residual oils adsorbed onto mineral or organic matter surfaces the free and adsorbed residual oils exhibit marked compositional differences due to fractional adsorption effects and maturity variations monitoring the pressures at the inlet and outlet positions of the extraction cell allows the measurement of pressure gradients across the core enabling the calculation of the relative permeability of the sample according to darcy s law application of the sequential flow through extraction method gives a substantial increase in information on the rock sample allowing a better understanding of fluid flow and fluid rock interaction in the subsurface

the clementine bistatic radar experiment during the clementine 1 mission a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle beta for selected lunar areas observations of the lunar south pole yield a same sense polarization enhancement around beta 0 analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole radar observations of periodically solar illuminated lunar surfaces including the north pole yielded no such enhancement a probable explanation for these differences is the presence of low loss volume scatterers such as water ice in the permanently shadowed region at the south pole

fluxes of fast and epithermal neutrons from lunar prospector evidence for water ice at the lunar poles maps of epithermal and fast neutron fluxes measured by lunar prospector were used to search for deposits enriched in hydrogen at both lunar poles depressions in epithermal fluxes were observed close to permanently shaded areas at both poles the peak depression at the north pole is 4 6 percent below the average epithermal flux intensity at lower latitudes and that at the south pole is 3 0 percent below the low latitude average no measurable depression in fast neutrons is seen at either pole these data are consistent with deposits of hydrogen in the form of water ice that are covered by as much as 40 centimeters of desiccated regolith within permanently shaded craters near both poles

temporal resolution of an oil charging history a case study of residual oil benzocarbazoles from the gidgealpa field reservoired oil is usually a mixture of multiple discrete petroleum charges unravelling the contribution and character of each charge is amongst the most daring challenges in petroleum geochemistry this paper describes an approach that involves the evaluation of both free and residual oils to reconstruct the history of petroleum accumulation within the multireservoir gidgealpa field located in the cooper and eromanga basins of central australia porewall coating residual oils form by reservoir wetting processes and grow continuously by adsorption of polar compounds retaining molecular information on the first oil that was present in the pore system such sequentially recovered residual oils proved useful in reconstructing the record of oil charges to the gidgealpa ridge using araucariacaean markers for source discrimination and the benzocarbazole a a c ratio bcr for identification of the source region five discrete charging events were distinguished in contrast to most previous studies benzocarbazole distributions were found to be independent of lithofacies organic facies and maturity however alkylated carbazoles did exhibit a pronounced facies dependency the application of alkylcarbazoles as source markers in the study area provides the first evidence of the expulsion of petroleum from cambrian marine source rocks in the underlying warburton basin 2007 elsevier ltd all rights reserved

europa ganymede and callisto new radar results from arecibo and goldstone observations of the icy galilean satellites conducted during 1987 1991 with the arecibo 13 cm system and the goldstone 3 5 cm system yield significant improvements in our knowledge of the satellites radar properties hardly any wavelength dependence is seen for either the total power radar albedo or the circular polarization ratio c for europa ganymede and callisto our 13 cm estimates of mean values and rms dispersions are 1 39 0 14 and 0 69 0 06 and c 1 53 0 03 1 43 0 06 and 1 17 0 04 radar albedo features are seen on each satellite evidence for c features is lacking except for indications of a weak hemispheric asymmetry for callisto that intersatellite and intrasatellite fractional variations in albedo greatly exceed variations in c is consistent with predictions of coherent backscatter theory and implies that albedo might be a crude indicator of relative silicate abundance the satellites albedo distributions overlap the most prominent radar features are tentatively identified with galileo regio and the valhalla basin estimates of echo doppler frequencies show callisto to be lagging its ephemeris by 200 50 km

sea surface temperatures around the australian margin and indian ocean during the last glacial maximum abstract we present new last glacial maximum lgm sea surface temperature sst maps for the oceans around australia based on planktonic foraminifera assemblages to provide the most reliable sst estimates we use the modern analog technique the revised analog method and artificial neural networks in conjunction with an expanded modern core top database all three methods produce similar quality predictions and the root mean squared error of the consensus prediction the average of the three under cross validation is only 0 77 c we determine lgm sst using data from 165 cores most of which have good age control from oxygen isotope stratigraphy and radiocarbon dates the coldest sst occurred at 20 500 1400 cal yr bp predating the maximum in oxygen isotope records at 18 200 1500 cal yr bp during the lgm interval we observe cooling within the tropics of up to 4 c in the eastern indian ocean and mostly between 0 and 3 c elsewhere along the equator the high latitudes cooled by the greatest degree a maximum of 7 9 c in the southwest pacific ocean our maps improve substantially on previous attempts by making higher quality temperature estimates using more cores and improving age control

initial results for the north pole of the moon from mini sar chandrayaan 1 mission 1 we present new polarimetric radar data for the surface of the north pole of the moon acquired with the mini sar experiment onboard india s chandrayaan 1 spacecraft between mid february and mid april 2009 mini sar mapped more than 95 of the areas polewards of 80 latitude at a resolution of 150 meters the north polar region displays backscatter properties typical for the moon with circular polarization ratio cpr values in the range of 0 1 0 3 increasing to over 1 0 for young primary impact craters these higher cpr values likely reflect surface roughness associated with these fresh features in contrast some craters in this region show elevated cpr in their interiors but not exterior to their rims almost all of these features are in permanent sun shadow and correlate with proposed locations of polar ice modeled on the basis of lunar prospector neutron data these relations are consistent with deposits of water ice in these craters

stable isotope clue to episodic sea ice formation in the glacial north atlantic sea ice is a determinant parameter of the climate system which acts as amplifier through positive ice albedo feedbacks and induces deep water formation through brine production it is also one of the most elusive parameters in the paleoclimate record most proxies of sea ice provide information on its presence and extent of e g diatoms or dinocysts but do not permit assessment on its rate of formation however seemingly off equilibrium low 18o values in mesopelagic planktic foraminifer species as observed today in the arctic ocean are thought to relate to the production of isotopically light brines during sea ice formation and might thus provide a clue on the rate of sea ice growth with reference to the isotopic properties of modern planktic foraminifers in the arctic ocean and using multi proxy data sets from the last glacial stage in the northwest north atlantic we re examined some of the current interpretations of planktic isotope records in the glacial nw north atlantic the large amplitude light isotopic excursions recorded in neogloboquadrina pachyderma left coiling during heinrich events 1 for example correspond to extensive sea ice cover as reconstructed from dinocysts and do not seem unequivocally linked to low salinity pulses such light isotopic excursion more likely responded to enhanced rates of sea ice formation resulting in the production and sinking of isotopically light brines on the contrary the isotopically heavy planktic foraminifers of the last glacial maximum lgm interval stricto sensu would rather suggest relatively low rates of brine production thus low sea ice growth rates in the area this would imply that the lgm distribution of sea ice in the north atlantic was primarily linked to spreading and drifting from marginal and nordic source areas and not from enhanced in situ production at the scale of glacial interglacial cycles isotopic distillation processes relating to sea ice production at high latitudes could be one of the factors controlling the 18o salinity relationship in deep ocean water masses that might deserve closer examination as it would be independent of continental ice volume changes

distribution of large emiliania huxleyi in the central and northeast atlantic as a tracer of surface ocean dynamics during the last 25 000 years the coccolithophore species emiliania huxleyi is characterized by a wide range of sizes which can be easily distinguished in the light microscope in this study we have quantified the abundance of

constraints on surface seawater oxygen isotope change between the last glacial maximum and the late holocene abstract estimates of the change in surface seawater 18 o 18 o sw between the last glacial maximum lgm and late holocene lh are derived from homogenous data sets with rigorous age control namely margo sea surface temperature sst estimates and oxygen isotopic ratios 18 o of planktonic foraminifers propagation of uncertainties associated with each proxy allows the identification of robust patterns of change in 18 o sw examination of these patterns on a regional scale highlights which changes in surface currents and hydrological cycle are consistent with both planktonic isotopic data and reconstructed sst positive local annual mean lgm lh 18 o sw anomalies characterize the glacial tropical indian ocean portions of the western and eastern margins of the north pacific the iberian margin and the tropical north atlantic as well as the south african margin although reduced precipitation during the lgm with respect to the lh may have contributed to some extent to these local enrichments in surface seawater 18 o the largest positive anomalies appear to be related to changes in ocean circulation large local negative annual mean lgm lh 18 o sw anomalies are found in the south pacific and north atlantic reflecting the equatorward migration of surface temperature fronts during the lgm with respect to the lh in the northern north atlantic a region characterized by large discrepancies between sst estimates based on different proxies only sst estimates based on planktonic foraminifer counts yield annual mean lgm lh 18 o sw anomalies consistent with a southward shift of the polar front at the lgm relative to the lh

circular polarization ratio characteristics of impact craters from mini rf observations and implications for ice detection at the polar regions of the moon 1 in an attempt to reduce the ambiguity on radar detection of water ice at the permanently shadowed regions near the lunar poles radar echo strength and circular polarization ratio cpr of impact craters are analyzed using the miniature radio frequency mini rf radar data from the lunar reconnaissance orbiter mission eight typical craters among over 70 craters are selected and classified into four categories based on their locations and cpr characteristics polar anomalous polar fresh nonpolar anomalous and nonpolar fresh the influences on cpr caused by surface slope rocks and dielectric constant are analyzed quantitatively using high resolution topography data and optical images a two component mixed model for cpr that consists of a normal surface and a rocky surface is developed to study the effect of rocks that are perched on lunar surface and buried in regolith our analyses show that inner wall of a typical bowl shaped crater can give rise to a change of about 30 in local incidence angle of radar wave which can further result in a cpr difference of about 0 2 there is a strong correlation between mini rf cpr and rock abundance that is obtained from high resolution optical images and predictions from the two component mixed model match well with the observed cprs and the estimated rock abundances statistical results show that there is almost no apparent difference in cpr characteristics between the polar and nonpolar anomalous craters or between the polar and nonpolar fresh craters the enhanced cpr in the interior of anomalous craters is most probably caused by rocks that are perched on lunar surface or buried in regolith instead of ice deposits as suggested in previous studies

glacial mediterranean sea surface temperatures based on planktonic foraminiferal assemblages we present a new reconstruction of mediterranean sea surface temperatures sst during the last glacial maximum lgm a calibration data set based on census counts of 23 species of planktonic foraminifera in 129 north atlantic and 145 mediterranean core top samples was used to develop summer winter and annual average sst reconstructions using artificial neural networks anns and the revised analogue method ram prediction errors determined by cross validation of the calibration data set ranged between 0 5 and 1 1 c with both techniques being most successful in predicting winter ssts glacial reconstructions are based on a new expanded data set of 273 samples in 37 cores with consistent minimum level of age control the new lgm reconstructions suggest that the east west temperature gradient during the glacial summer was 9 c whereas during the glacial winter the gradient was 6 c both some 4 c higher than that existing today in contrast to earlier studies our results tend to suggest much cooler sst estimates throughout the glacial mediterranean particularly in the eastern basin where previous sst reconstructions indicated a decrease of only 1 c our new sst reconstructions will provide the modelling community with a detailed and updated portrayal of the mediterranean sea during the lgm setting new targets on which glacial simulations can be tested

a natural pyrolysis experiment hopanes from hopanoic acids abstract the formation or generation of hopanes are important processes during both the natural heating of organic rich sediments and laboratory pyrolysis experiments molecular maturity parameters as well as the amounts ng g rock of the c31 hopanes and c30 c32 hopanoic acids were quantified in a jurassic silty shale horizon isle of skye scotland as a function of distance from an igneous intrusion the maturity profiles of the homohopanes and the hopanoic acids are comparable there is also a correlation between the decreasing amounts of c30 c32 hopanoic acids and concomitant increases in c29 c31 hopanes suggesting that free hopanoic acids could be one potential source of hopanes in this particular horizon other possible sources could include hopanoic acids that are bound into the macromolecular fraction

last glacial maximum lgm primary productivity in the northern north atlantic oceanthis article is one of a series of papers published in this special issue on the theme polar climate stability network to reconstruct oceanic primary productivity in the northern north atlantic ocean during the last glacial maximum lgm we have applied the modern analogue technique to dinocyst assemblages using a northern hemisphere database that includes 1171 reference sites the reconstructions were made in lgm sediments 21 2 ka of a set of 62 cores collected from 36 n to 75 n here we present the compilation of reconstructed seasonal and annual productivity during the lgm results show lower mean annual productivity during the lgm than at present in the northern north atlantic at most high latitude locations lgm productivity has been estimated at 200 gc m 2 a 1 with extremely low values 100 gc m 2 a 1 in the labrador sea baffin bay and along the margins of greenland such low values might be the result of reduced atlantic meridional overturning circulation and stratified water that characterized the glacial episode of the north atlantic ocean

characterisation of sedimentary organic matter by bulk and molecular geochemical proxies an example from oligocene maar type lake enspel germany abstract characterisation of organic matter composition of fossil lake sediments is important in reconstruction of fossil ecosystems and paleoclimates high time resolved organic matter analysis is needed to characterize sediments from small lake environments due to their rapidly changing environmental conditions a suitable technique for rapid analysis of organic matter in such sediments is rock eval pyrolysis in small lakes however routine interpretation of rock eval data can be misleading lack of tributaries capable of transporting larger woody fragments into small lakes causes a bias towards the input of lipid rich leaf waxes and cuticles this hydrogen rich and oxygen depleted terrigenous organic matter hi 250 600 mg hc g toc and oi 20 40 mg co 2 g toc can easily be misinterpreted as being of algal origin differentiation of terrigenous plant derived hydrogen rich organic matter from algal organic matter is readily achieved by including c n elemental ratios and lipid biomarker data

late archean molecular fossils from the transvaal supergroup record the antiquity of microbial diversity and aerobiosis abstract cores recovered during the agouron griqualand drilling project contain over 2500 m of well preserved late archean transvaal supergroup sediments dating from ca 2 67 to 2 46 ga bitumen extracts of these strata were obtained using clean drilling sampling and analysis protocols that avoided overprinting syngenetic molecular fossil signatures with contaminant hydrocarbons comparisons of biomarker contents in stratigraphically correlated intervals from diverse lithofacies in two boreholes separated by 24 km as well as across a 2 gyr unconformity provide compelling support for their syngenetic nature the suite of molecular fossils identified in the late archean bitumens includes hopanes attributable to bacteria potentially including cyanobacteria and methanotrophs and steranes of eukaryotic origin this molecular fossil record supports an origin in the archean eon of the three domains of cellular life as well as of oxygenic photosynthesis and the anabolic use of o2

lunar polar craters icy rough or just sloping abstract circular polarisation ratio cpr mosaics from mini sar on chandrayaan 1 and mini rf on lro are used to study craters near to the lunar north pole the look direction of the detectors strongly affects the appearance of the crater cpr maps rectifying the mosaics to account for parallax also significantly changes the cpr maps of the crater interiors it is shown that the cprs of crater interiors in unrectified maps are biased to larger values than crater exteriors because of a combination of the effects of parallax and incidence angle using the lola digital elevation map dem the variation of cpr with angle of incidence has been studied for fresh craters cpr 0 7 with only a weak dependence on angle of incidence or position interior or just exterior to the crater consistent with dihedral scattering from blocky surface roughness for anomalous craters the cpr interior to the crater increases with both incidence angle and distance from the crater centre central crater cprs are similar to those in the crater exteriors cpr does not appear to correlate with temperature within craters furthermore the anomalous polar craters have diameter to depth ratios that are lower than those of typical polar craters these results strongly suggest that the high cpr values in anomalous polar craters are not providing evidence of significant volumes of water ice rather anomalous craters are of intermediate age and maintain sufficiently steep sides that sufficient regolith does not cover all rough surfaces

diagenetic and detrital origin of moretane anomalies through the permian triassic boundary abstract many biogeochemical anomalies coincide with the late permian extinction lpe 252 28 ma several mechanisms have been proposed to explain the moretane hopane anomaly that has been identified in samples from meishan gssp section in southeastern china here we report homohopane 2 and 3 methylhomohopane and lithological data for a drill core from the meishan section in southeastern china three intervals of elevated c 30 moretane hopane ratios are recorded in the lungtan yinkeng and helongshan formations moretane hopane ratios of c 31 34 homohopanes and the 2 and 3 methylhomohopanes display the same stratigraphic patterns as the c 30 moretane hopane record in light of the multiple and parallel moretane anomalies for the homohopane and 2 and 3 methylhomohopane series enhanced input from higher plant organic matter such as coal and peat does not adequately explain the observed isomer patterns correlation of high moretane hopane ratios with low c 35 homohopane index hhi and high hopane sterane values suggest increased input of hopanoids from oxic soils additionally moretane hopane ratios show excellent correlations with total clay percentages and specific clay types particularly chlorite illite and mixed layer illite smectite we conclude that a combination of episodic hopanoid input from soil bacteria and diagenetic effects related to redox and detrital clays generated the unique moretane hopane patterns at meishan similar relationships of ts ts tm with redox source indicators and lithology indicate that ts ts tm is affected by the same factors controlling the moretane hopane ratios berthierine a clay that requires reducing conditions for formation was detected in samples from the lungtan formation we are unable to determine from our results whether the berthierine is authigenic or detrital but future determination of the origin of berthierine at meishan may offer additional environmental insight no link between diasteranes and lithology was observed in this study suggesting that diasteranes are relatively unaffected by the detrital clay component of the meishan sediments in total the results point toward the complex role of source input lithology and depositional redox conditions in the transformation of organic matter during maturation future work is required to elucidate the lithological effects on diagenetic processes including biomarker genesis isomerization and thermal degradation

reconstruction of the glacial atlantic and pacific sea surface temperatures from assemblages of planktonic foraminifera multi technique approach based on geographically constrained calibration datasets

assessing biomarker syngeneity using branched alkanes with quaternary carbon baqcs and other plastic contaminants biomarker molecules are valuable for the elucidation of ancient microbial ecosystems and the characterization of petroleum source rocks for such studies acquisition of reliable hydrocarbon data and proof of their syngeneity are essential however contamination of geological samples with anthropogenic petroleum products during drilling storage and sampling can be particularly problematic because these hydrocarbons may over print an original indigenous biomarker profile to evaluate the extent of contamination of drill core and outcrop material we studied the distribution of hydrocarbons in 26 rocks from different locations in the world all rocks had petroleum products on their exterior surfaces twenty two samples also contained surficial hydrocarbons derived from polyethylene plastic including branched alkanes with quaternary carbon centers baqcs and alkylcyclopentanes with pronounced even over odd carbon number preference using three examples from the paleoproterozoic tawallah and mcarthur groups in northern australia we show how indigenous biomarkers can be recognized by comparing hydrocarbon distributions between exterior rock surfaces and the rock interior and how infiltration of allochthonous hydrocarbons can be assessed through the spatial distribution of characteristic polyethylene derived hydrocarbons in the rock the methods outlined in this paper give confidence in the interpretation of biomarkers in particularly sensitive applications such as the first occurrences of certain organisms in the geological record and the provenance of organic matter in meteorites

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

initial observations from the lunar orbiter laser altimeter lola as of june 19 2010 the lunar orbiter laser altimeter an instrument on the lunar reconnaissance orbiter has collected over 2 0 10 9 measurements of elevation that collectively represent the highest resolution global model of lunar topography yet produced these altimetric observations have been used to improve the lunar geodetic grid to 10 m radial and 100 m spatial accuracy with respect to the moon s center of mass lola has also provided the highest resolution global maps yet produced of slopes roughness and the 1064 nm reflectance of the lunar surface regional topography of the lunar polar regions allows precise characterization of present and past illumination conditions lola s initial global data sets as well as the first high resolution digital elevation models dems of polar topography are described herein

alkenone paleothermometry biological lessons from marine sediment records off western south america an empirical global core top calibration that relates the alkenone unsaturation index u k 0 37 to mean annual sst masst is statistically the same as that defined for a subarctic pacific strain of emiliania huxleyi ccmp1742 grown exponentially in batch culture under isothermal conditions although both equations have been applied widely for paleosst reconstruction uncertainty still stems from two key ecological factors variability in the details of biosynthesis among genetically distinct alkenone producing strains and impacts of nonthermal physiological growth factors on u k 0 37 new batch culture experiments with ccmp1742 here reveal that u k 0 37 diverge systematically from the core top calibration in response to nutrient depletion and light deprivation two physiological stresses experienced by phytoplankton populations in the real ocean other aspects of alkenone alkenoate composition also respond to these stresses and may serve as signatures of such effects providing an opportunity to detect understand and potentially correct for such impacts on the geologic record a test case documents that sediments from the southeast pacific display the alkenone alkenoate compositional signature characteristic of cells physiologically stressed by light deprivation such an observation could be explained if marine snow provided a major vector of sedimentation for these biomarkers late pleistocene u k 0 37 records in the southeast pacific yield plausible paleotemperature histories of ice age cooling but ice age alkenone alkenoate signatures fall outside the range of modern calibration samples of similar u k 0 37 they better match core top samples deposited beneath waters characterized by much cooler masst suggesting key features of ice age ecology for alkenone producing haptophytes were different from today and that the u k 0 37 index taken alone may misgauge the total range of ice age cooling at these locations analysis of the full spectrum of alkenone alkenoate compositions preserved in sediments opens up a new opportunity that may improve the accuracy of paleotemperature estimates based on simple u k 0

near surface temperatures on mercury and the moon and the stability of polar ice deposits abstract in order to assess the thermal stability of polar ice deposits we present model calculated temperatures of flat surfaces and surfaces within bowl shaped and flat floored polar impact craters on mercury and the moon our model includes appropriate insolation cycles realistic crater shapes multiple scattering of sunlight and infrared radiation and depth and temperature dependent regolith thermophysical properties unshaded water ice deposits on the surface of either body are rapidly lost to thermal sublimation a subsurface water ice deposit is stable within 2 latitude of the moon s poles meter thick water ice deposits require billions of years to sublime if located in the permanently shaded portions of flat floored craters within 10 latitude of the poles of mercury and 13 latitude of the poles of the moon results for craters associated with radar features on mercury are consistent with the presence of stable water ice deposits if a thin regolith layer thermally insulates deposits at lower latitudes and within smaller craters a regolith cover would also reduce losses from diffusion ion sputtering impact vaporization and h ly and is implied independently by the radar observations permanently shaded areas near the moon s poles are generally colder than those near mercury s poles but the moon s obliquity history its orbit through earth s magnetospheric tail and its radar opaque regolith may limit the volume and radar detectability of ice deposits there

origin of petroleum in the neoproterozoic cambrian south oman salt basin abstract the south oman salt basin sosb is host to the world s oldest known commercial deposits most of the south oman oils have been proven to be associated with the source rocks of the neoproterozoic to cambrian huqf supergroup but the assignment of oils to specific huqf intervals or facies has been hampered by the geochemical similarity of the organic matter across the entire huqf sequence possibly as a consequence of limited change in the local palaeoenvironment and biota over the time of its deposition this study was conducted to establish improved correlations between organic rich rock units and reservoir fluids in the sosb through detailed molecular and isotopic analysis of the huqf supergroup with special emphasis directed towards understanding the ara carbonate stringer play unusual biomarkers tentatively identified as a norsteranes show distinctive patterns among carbonate stringer oils and rocks different from those observed in nafun sediments and ara rocks from the athel basin these putative a norsteranes form the basis for new oil source correlations in the sosb and provide for the first time geochemical evidence of a self charging mechanism for the carbonate stringer play the paucity of markers specific to the nafun group shuram buah and masirah bay formations confounds attempts to quantify their respective contributions to huqf oil accumulations nafun inputs can only be determined on the basis of subtle differences between nafun and ara biomarker ratios the most useful geochemical characteristics delineating nafun group organic matter from ara group intra salt source rocks included low relative abundance of mid chain monomethyl alkanes x compounds low relative abundance of gammacerane 28 30 dinorhopane 25 28 30 trinorhopane and 2 methylhopanes low c 22 t c 21 t and high c 23 t c 24 t cheilanthanes ratio values based on these parameters molecular evidence for major contributions of liquid hydrocarbons from nafun group sediments shuram buah and masirah bay formations is lacking our results suggest that the majority of sosb hydrocarbon accumulations originate from within the ara group either from the carbonate stringers or from the package of sediments that comprises the thuleilat athel silicilyte and u shale formations subtle aspects of the composition of some carbonate stringer and post salt huqf oils could suggest some degree of sourcing from the nafun rocks but stronger evidence is needed to confirm this

clay mineral distribution in surface sediments of the south atlantic sources transport and relation to oceanography abstract surface samples mostly from abyssal sediments of the south atlantic from parts of the equatorial atlantic and of the antarctic ocean were investigated for clay content and clay mineral composition maps of relative clay mineral content were compiled which improve previous maps by showing more details especially at high latitudes large scale relations regarding the origin and transport paths of detrital clay are revealed high smectite concentrations are observed in abyssal regions primarily derived from southernmost south america and from minor sources in southwest africa near submarine volcanoes of the antarctic ocean south sandwich bouvet island smectite contents exhibit distinct maxima which is ascribed to the weathering of altered basalts and volcanic glasses the illite distribution can be subdivided into five major zones including two maxima revealing both south african and antarctic sources a particularly high amount of mg and fe rich illites are observed close to east antarctica they are derived from biotite bearing crystalline rocks and transported to the west by the east antarctic coastal current chiorite and well crystallized dioctaedral illite are typical minerals enriched within the subantarctic and polarfrontal zone but of minor importance off east antarctica kaolinite dominates the clay mineral assemblage at low latitudes where the continental source rocks west africa brazil are mainly affected by intensive chemical weathering surprisingly a slight increase of kaolinite is observed in the enderby basin and near the filchner ronne ice shelf the investigated area can be subdivided into ten large scale clay facies zones with characteristic possible source regions and transport paths clay mineral assemblages of the largest part of the south atlantic especially of the western basins are dominated by chlorite and illite derived from the antarctic peninsula and southernmost south america and supported by advection within the circumantarctic deep water flow in contrast the east antarctic provinces are relatively small assemblages of the eastern basins north of 30 s are strongly influenced by african sources controlled by weathering regimes on land and by a complex interaction of wind river and deep ocean transport the strong gradient in clay mineral composition at the brazilian slope indicate a relatively low contribution of tropically derived assemblages to the western basins

sea ice in the paleoclimate system the challenge of reconstructing sea ice from proxies an introduction sea ice is an important component of the earth system with complex dynamics imperfectly documented from direct observations which are primarily limited to the last 40 years whereas large amplitude variations of sea ice have been recorded especially in the arctic with a strikingly fast decrease in recent years partly attributed to the impact of anthropogenic climate changes little is known about the natural variability of the sea ice cover at multi decadal to multi millennial time scales hence there is a need to establish longer sea ice time series to document the full range of sea ice variations under natural forcings to do this several approaches based on biogenic or geochemical proxies have been developed from marine ice core and coastal records the status of the sea ice proxies has been discussed by the sea ice proxy sip working group endorsed by pages during a first workshop held at geotop in montreal the present volume contains a set of papers addressing various sea ice proxies and their application to large scale sea ice reconstruction here we summarize the contents of the volume including a table of various proxies available in marine sediments and ice cores with their possibilities and limitations

an upper limit for ice in shackleton crater as revealed by lro mini rf orbital radar 1 although diverse measurements have indicated h oh or h2o species in the lunar polar regions pinpointing its location form and abundance in specific reservoirs has proven elusive here we report on the first orbital radar measurements of shackleton crater near the lunar south pole mini rf observations indicate a patchy heterogeneous enhancement in cpr circular polarization ratio on the crater walls whose strength decreases with depth toward the crater floor a result that is most consistent with a roughness effect due to less mature regolith present on the crater wall slopes however the results do not rule out a modest ice contribution and an upper limit of 5 10 wt h2o ice up to 30 vol present in the uppermost meter of regolith is also consistent with the observations

kerogen origin evolution and structure kerogen commonly defined as the insoluble macromolecular organic matter om dispersed in sedimentary rocks is by far the most abundant form of om on earth this fossil material is of prime importance as the source of oil and natural gas moreover kerogen can provide essential information on major topics such as past environments climates and biota this review reports the main advances in kerogen studies since the comprehensive synthesis edited by durand durand b ed kerogen insoluble organic matter from sedimentary rocks editions technip paris 1980 it is organized into eight sections the first two are concerned with the successive definitions of kerogen and the definition used here the different techniques used for kerogen isolation without loss or degradation and basic kerogen analysis the third and fourth focus on sedimentary om sources and preservation processes in relation to depositional environment including sedimentation conditions favourable for kerogen accumulation and extrapolation to past geological time great strides have been made in the latter topics over the last 25 years owing to a combination of classical studies in organic geochemistry and studies in other domains such as biogeochemistry oceanography hydrology and soil science along with the development of powerful analytical tools the next two sections deal with the different kerogen classifications by type and kerogen evolution and maturation upon burial in sediments structural modelling of coal and kerogen based on physical and or chemical structural analysis is described in the following section although only statistical the models thus derived provide a synthetic view of the main structural resemblances and differences among various samples in relation to source maturity or physicochemical properties finally the last section explores some of the advances in kerogen understanding expected for the near future the review includes a list containing about 500 references

comparing proxies for the reconstruction of lgm sea surface conditions in the northern north atlantic abstract within the frame of the multiproxy approach for the reconstruction of the glacial ocean margo project sea surface conditions of the last glacial maximum lgm 23 19 ka were reconstructed using different proxies which were calibrated to a standardized modern hydrography in the north atlantic the revised lgm margo data set provides a comprehensive coverage including the nordic seas the data set includes reconstruction based on planktonic foraminifer assemblages dinocyst assemblages alkenone coccolithophorid biomarkers and mg ca ratios in planktonic foraminifers several hydrological features of the lgm north atlantic can be identified that are supported by all four proxies they include an extensive perennial sea ice cover along the eastern canadian and greenland margins seasonally ice free central north atlantic and norwegian sea and the winter sea ice limit being located at about 55 n all proxies also suggest significantly colder than modern sea surface conditions in the southeastern part of the north atlantic and a more zonal temperature pattern than at present with a steep sst gradient of the order of 10 c between 40 n and 45 n however in the nordic seas large discrepancies remain well above the level of uncertainty of the sst reconstructions these discrepancies might be related to stratification of the upper water mass linked to large annual amplitude of temperature with contrasting winter and summer conditions high interannual interdecadal variability or taphonomic processes affecting some of the proxies the average lgm sst in the nordic seas cannot at present be assessed with confidence however the existing evidence suggests that highly variable sea surface conditions and at least occasional advection of north atlantic waters may have characterised the glacial nordic seas

microscopic and sedimentologic evidence for the generation and migration of hydrocarbons in toarcian source rocks of different maturities abstract this study is part of a comprehensive research program on the generation and migration of petroleum from the organic rich posidonia shale lower toarcian jurassic of the hils syncline northern germany four cores of the complete posidonia shale with varying amounts of underlying pliensbachian and overlying aalenian mudstones provided the sample base depending upon their distance from a presumed subjacent heat source the vlotho massif the cores display progressive levels of increasing thermal maturation with r 0 values 0 48 0 68 0 88 and 1 45 which span the limits of the oil generation window primary stratigraphic lithologic and petrographic attributes of the four sections are all very similar each includes a lower marlstone member about 5 m thick overlain by 11 31 m of calcareous clay shale clay minerals calcite pyrite kerogen and quartz are the principal constituents thus there is no evidence that depositional conditions of the posidonia shale varied significantly over the sampled area the omnipresence of framboidal pyrite clearly formed from the activity of sulphate reducing bacteria at or near the depositional interface is strong evidence that uniform reducing anoxic conditions were persistent at all localities this conclusion supports the assumption that initially each section was identical in overall properties and that significant differences observed in geochemistry organic macerals and other properties are directly related to the variable levels of thermal maturation kerogen from the least mature section r o 0 48 is type ii and composed of alginite a alginite b liptodetrinite bituminite and some terrestrial sporinite vitrinite and inertinite macerals with increasing maturation the alginite macerals exhibit a progressive change in morphology and fluorescence properties alginite of the least mature section displays a strong green fluorescence at 0 68 r o alginite macerals exhibit yellow orange fluorescence and are structurally well preserved although geochemical data indicate generation and loss of large amounts of oil at 0 88 r o hydrocarbon generation is almost complete and few primary alginites remain they have been transformed into secondary liptinites designated as metaalginite which have similar fluorescence colours at the highest maturation level 1 45 r o metaalginites are only weakly fluorescent with a shift toward red colours calcite and or bitumen filled bedding plane micro and macrofractures occur exclusively in the organic rich posidonia shale at maturity levels of 0 68 r o and above such features are totally absent in the immature posidonia section and in the adjacent organic poor mudstones this observation indicates that the fractures developed in direct response to overpressuring i e pore pressure exceeding lithologic load related to oil and gas generation in the source rock the fractures undoubtedly provided important expulsion conduits for generated products

no evidence for thick deposits of ice at the lunar south pole the rim of the shackleton crater at the lunar south pole is a candidate crash site for nasa s lcross probe lunar crater observation and sensing satellite due to launch in 2008 the plume of debris kicked up by the crash is to be analysed in the hope that it will reveal the water thought to be there suggestions of lunar ice date from 1996 when data from the clementine spacecraft gave some indications of the presence of ice on crater walls at the south pole now using high resolution radar imagery the radar scattering parameter thought indicative of thick ice deposits has been found also to match radar echoes from the rock strewn walls and ejecta of young impact craters at all lunar latitudes there is no evidence for thick ice though there could be grains of water ice spread more thinly through the lunar soil shackleton crater at the moon s south pole has been suggested as a possible site of concentrated deposits of water ice on the basis of modelling of bi static radar polarization properties and interpretations of earlier earth based radar images1 2 this suggestion and parallel assumptions about other topographic cold traps is a significant element in planning for future lunar landings hydrogen enhancements have been identified in the polar regions3 but these data do not identify the host species or its local distribution the earlier earth based radar data lack the resolution and coverage for detailed studies of the relationship between radar scattering properties cold traps in permanently shadowed areas and local terrain features such as the walls and ejecta of small craters here we present new 20 m resolution 13 cm wavelength radar images that show no evidence for concentrated deposits of water ice in shackleton crater or elsewhere at the south pole the polarization properties normally associated with reflections from icy surfaces in the solar system4 5 6 were found at all the observed latitudes and are strongly correlated with the rock strewn walls and ejecta of young craters including the inner wall of shackleton there is no correlation between the polarization properties and the degree of solar illumination if the hydrogen enhancement observed by the lunar prospector orbiter3 indicates the presence of water ice then our data are consistent with the ice being present only as disseminated grains in the lunar regolith

bistatic radar observations of the moon using mini rf on lro and the arecibo observatory the miniature radio frequency mini rf instrument aboard nasa s lunar reconnaissance orbiter lro is a hybrid dual polarized synthetic aperture radar sar that operated in concert with the arecibo observatory to collect bistatic radar data of the lunar nearside from 2012 to 2015 the purpose of this bistatic campaign was to characterize the radar scattering properties of the surface and near surface as a function of bistatic angle for a variety of lunar terrains and search for a coherent backscatter opposition effect indicative of the presence of water ice a variety of lunar terrain types were sampled over a range of incidence and bistatic angles including mare highland pyroclastic crater ejecta and crater floor materials responses consistent with an opposition effect were observed for the ejecta of several copernican aged craters and the floor of the south polar crater cabeus the responses of ejecta material varied by crater in a manner that suggests a relationship with crater age the response for cabeus was observed within the portion of its floor that is not in permanent shadow the character of the response differs from that of crater ejecta and appears unique with respect to all other lunar terrains observed analysis of data for this region suggests that the unique nature of the response may indicate the presence of near surface deposits of water ice

modeling radar scattering from icy lunar regoliths at 13 cm and 4 cm wavelengths 1 two orbital synthetic aperture radars sars the chandrayaan 1 mini sar 13 cm wavelength and the lunar reconnaissance orbiter lro mini rf 13 and 4 2 cm wavelengths have been imaging the lunar surface searching for ice deposits in the polar permanently shadowed areas to understand the radar signatures of lunar polar ices an empirical two component model with parametric variations of the specular and diffuse components was developed and validated this model estimates scattering differences associated with slopes surface roughness thin regolith over ice and patches of ice lunar radar backscatter cross sections for the average surface for the chandrayaan 1 and lro instruments are estimated from the radar cross sections from the moon at 3 8 23 and 68 cm wavelengths measured in the 1960s at the massachusetts institute of technology this modeling predicts that enhanced diffuse scattering from near surface ice can be separated from rocks if the scattering is characterized by both the high reflectivity and circular polarization ratios cprs like those observed on mercury mars and the galilean satellites scattering from near surface ices covered by a thin regolith can be separated from rocks if the enhancement is twice the average or more if however the lunar ice is dispersed throughout the regolith as ice filling pores then scattering differences might be too small to detect preliminary validation using lro radar data for a few polar and midlatitude craters indicate that the observed cprs are consistent with our models for different regolith ice and roughness conditions

natural and artificial maturation of biological markers in a toarcian shale from northern germany steroid and terpenoid biological marker evolution was studied in a maturity sequence of lias toarcian shales and adjacent strata from three shallow boreholes in the hils syncline northern germany excellent facies control within the study area ensures the comparability of the organic matter type among the stratigraphically equivalent samples of the natural maturation series in the early hydrocarbon generation stage 0 68 r0 a strong facies dependence of some sterane and hopane isomerisation values was found within the same borehole at only a few metres depth difference the extent of sterane isomerisation at c 14 and c 17 was close to 80 in the toarcian shale and between about 55 and 65 in the adjacent dogger and lias sediments similar differences were observed for the 17 h hopane moretane and 22 29 30 trisnor 18 h neohopane 22 29 30 trisnor 17 h hopane ratios whereas the 20s 20s 20r sterane isomerisation ratio did not show this difference the observed differences mostly disappear by the end of the main oil generation phase 0 88 ro where several reactions appear to have reached completion hydrous pyrolysis experiments by variations of time and temperature were used to simulate the natural evolution of the biological markers results for sterane isomerisation in the high temperature range were compared to those published by mackenzie and mckenzie geol mag 120 417 470 1983 for natural sediments kinetic data derived for this reaction from the hydrous pyrolysis results alone or from the combination of hydrous pyrolysis and natural data sets differ markedly from those determined by mackenzie and mckenzie 1983 the hydrous pyrolysis data alone yield an activation energy for sterane isomerisation at c 20 of 131 kj mol the combined data of 170 kj mol the frequency factors are in the 105 108 s 1 range the significance of the data is discussed in detail

30 norhopanes their occurrence in sediments and crude oils abstract sediments and crude oils have been analysed using gc ms techniques and shown to contain two homologous series of hopanes namely 30 nor 17 h hopanes and 25 30 bisnor 17 h hopanes as well as the common 17 h hopanes homologues c28 to c34 of the 30 nor 17 h hopane series have been identified in crude oils associated with carbonate source rocks the abundances of these hopanes relative to the 17 h hopanes in the soluble organic matter from carbonate sediments has been shown to depend upon sample maturity the more mature samples having higher relative abundances of these norhopanes a comparison of the relative abundances of the norhopanes in the soluble organic matter of sediments and in the hydrocarbon fraction released when the extracted sediments were pyrolysed showed that the 30 nor 17 h hopanes were more abundant in the pyrolysis product these observations indicate that the proportion of norhopanes relative to normal 17 h hopanes in bound form in the kerogen is greater than that present in the soluble form and so kerogen cracking proceeds with increased maturity of the sediments and a relative enrichment of these norhopanes occurs in the soluble fraction the series of 25 30 bisnor 17 h hopanes has been identified in a severely biodegraded crude oil from a putative carbonate source this observation together with the reported occurrence of enriched 25 norhopanes in severely biodegraded crude oils suggests that 25 30 bisnor 17 h hopanes may be biomarkers for severely biodegraded crude oils from carbonate rich source rocks

a comparison of thermal maturity parameters between freely extracted hydrocarbons bitumen i and a second extract bitumen ii from within the kerogen matrix of permian and triassic sedimentary rocks abstract in this study we compared various maturity dependent aromatic steroid and triterpenoid hydrocarbon ratios in bitumens that are freely extractable from sedimentary rocks bitumen i with those in second extracts that comprised hydrocarbons closely associated with the kerogen mineral matrix bitumen ii bitumen ii was released through kerogen isolation and demineralisation using hcl and hf h3bo3 the samples studied although of similar age come from different localities they represent a range of facies and two kerogen types ii and iii and all were deposited under marine conditions the results show that the more stable isomers of methylnaphthalene mn and methylphenanthrene mp are relatively more abundant in bitumen ii the difference between the methylnaphthalene ratio mnr of bitumens i and ii when plotted against the ratio of clay to total organic carbon clay toc gives an excellent correlation r2 0 88 the highest clay toc ratio corresponds with the biggest difference in mnr for the respective bitumens consistent with the more stable isomers being preferentially retained within the clay kerogen matrix since the mp isomers are higher in bitumen ii than in bitumen i it was anticipated that their methylphenanthrene index mpi 1 values a commonly used measure of thermal maturity would also be different for most samples the measured mpi 1 in bitumen i is generally higher than that in bitumen ii except for three samples thus showing a bias towards a lower thermal maturity for the second extract the opposite is true of the mp ratio and mnr this may be attributed to the fact that phenanthrene p which is part of the denominator in mpi 1 is more stable than its methylated counterparts steroid and triterpenoid maturity parameters also showed differences between the two extracts with c27 diasterane sterane and ts ts tm being higher in bitumen i only the former parameter is positively correlated with the clay toc ratio suggesting that clay content probably influences the diagenetic transformation of steroid precursors to diasteranes the observed differences between the maturity parameters of bitumen i and bitumen ii may be especially important in sedimentary rocks that contain high percentages of clay minerals

radar mapping of mercury s polar anomalies ground based radar observations of mercury have revealed unusually strong highly depolarized echoes from the north1 2 and south2 poles these anomalous echoes have been cited as evidence of polar ice deposits1 5 thermal studies3 5 suggest that the permanently shaded floors of large polar craters are cold enough to preserve water ice in a stable state over aeons in spite of mercury s proximity to the sun here we present high resolution radar maps of mercury s polar regions derived from delay doppler measurements we have resolved the north and south polar anomalies into numerous crater sized features and we have been able to identify the source craters for many of these features after making small corrections to the pole positions on the mariner 10 images the coincidence with crater locations together with other properties of the radar features are consistent with the polar ice hypothesis

a prolonged warm and humid interval during marine isotope stage 13 15 as revealed by hydrographic reconstructions from the south china sea images md972142 abstract variations of orbital driven insolation ice volume and greenhouse gas effects have been proposed as major controlling factors in determining the timing and amplitude of quaternary cyclic climate changes however it remains to be determined how the internal feedback in the tropical atmosphere and ocean and the coupling between the low and high latitude systems may have produced instability or non cyclic changes in the long term climate evolution such abnormalities have been reported increasingly from paleoclimatic reconstructions in east asia and the western pacific for a prolonged warm and humid climate interval during marine isotope stage mis 13 15 475 610 kya to better address the climate abnormality in mis 13 15 that has been observed in the western pacific here we report high resolution late quaternary planktic foraminifer faunal abundance and faunal sea surface temperature sst records from the international marine past global change images program core md972142 which was retrieved from the southeastern south china sea scs our results indicate that the faunal assemblages and ssts in the southeastern scs express a substantially prolonged unusual warm interglacial type climate condition in mis 13 15 the climate was abnormally warm during the cold mis 14 our study also suggests a lowering of sea surface salinity sss during mis 13 15 while the western pacific climate experienced a persistently warm and humid period at mis 14 a normal cooling 2 c condition on the surface of the eastern equatorial pacific existed concomitantly while assessing possible interpretations of this abnormal climate interval in mis 13 15 our study indicates that an enhanced interhemispheric and or longitudinal temperature gradient across the basin wide pacific cannot be ruled out a change in the sensitivity of the east asian monsoon eam that controlled temperature and precipitation patterns in east asia and the western pacific is probably also important or responsible for this climate abnormality based on our evidence we suggest that the tropical dynamics would have played a role in the climate abnormality in mis 13 15 through maintaining or even increasing the longitudinal sst gradient in the equatorial pacific which may have intensified the low latitude trade winds in the eastern component of the walker circulation that drove a longer duration and or stronger intensity of the summer vs winter eam

influence of bitumen 2 on rock eval pyrolysis abstract extractable organic matter bitumen 2 remaining in previously extracted whole rocks or in kerogen concentrates that have not been thoroughly extracted after rock demineralization can severely affect rock eval data for kerogens appearing in the s2 rather than the s1 peak the bitumen 2 acts to increase s2 yield we illustrate the results from the analyses of a mature source rock from offshore norway

improved methods for isolating and validating indigenous biomarkers in precambrian rocks hydrocarbon biomarkers in highly mature precambrian rocks have the potential to provide important information about the diversity ecology and evolution of early life but studying them presents special analytical challenges extractable hydrocarbons are present in archean and most paleoproterozoic sedimentary rocks in such trace concentration that even slight contamination from petroleum derived materials in situ or during drilling storage sampling handling and laboratory analysis would compromise the results and thereby any consequent inferences here we report protocols that we have developed for the analysis of cores from several recently completed deep time scientific drilling initiatives by paying special attention to cutting cleaning crushing and extraction it is possible to significantly reduce laboratory blanks to acceptable levels when these methods are utilized meaningful variations in the patterns of biomarkers over stratigraphic and lithologic boundaries provide compelling evidence for syngeneity

late quaternary paleoenvironmental reconstruction and paleoclimatic implications of the aegean sea eastern mediterranean based on paleoceanographic indexes and stable isotopes the late quaternary palaeoenvironmental evolution and the main palaeoceanographic changes of the aegean sea was reconstructed using planktonic foraminifera obtained from the sediments of a northern sk 1 and a southern ns 14 core site multivariate statistical approach including q mode cluster and principal component pca analyses gives an insight into the relationships between sea surface environmental changes between the north and south aegean and furthermore serves as a baseline data set for palaeoclimatic and palaeoceanographic reconstructions of the eastern mediterranean sea stable isotope analyses coupled with additional paleoceanographic sea surface temperature sst productivity ssp stratification s index upwelling u index seasonality sn index proxies provide insights into the sedimentological hydrographic and trophic evolution and ecosystem dynamics of the aegean sea and furthermore serve as a baseline data set for palaeoclimatic and palaeoceanographic reconstructions of the eastern mediterranean sea concentrating on the last 19 ka faunal and isotopic data concur suggesting a series of climatic zones corresponding to well known climatic phases of the last glacial cycle cold and arid conditions during the late glacial period were followed by a warmer and wetter climate trend during deglacial time a marked seasonality characterized by homogenous water column favored by efficient upwelling during the winter and by warm stratified water column during the summer has also been recognized during this period bolling allerod b a in both basins an abrupt switch to cool arid climatic event younger dryas yd suggests a strengthening of winter convection around 12 9 ka which seems to be more evident in the north aegean core however the more pronounced environmental changes between the north and south aegean sea were identified during the holocene and they coincide with the deposition of sapropel s1 and sapropel mid holocene smh the comparison between sk 1 and ns 14 records indicated significant changes in both the productivity and stratification patterns with the former the main factor in north aegean and the latter in south aegean for s1 deposition regarding the localized deposition of smh in the semi enclosed shallow south aegean site the fully oxygenated and less productive water column conditions prevailing during that time 5 4 4 3 ka in the north aegean were the limiting factor for its deposition

dating small fresh lunar craters with mini rf radar observations of ejecta blankets 1 the ages of large impact craters on the moon can be estimated by measuring the size frequency distribution of smaller craters superimposed on their ejecta but applying this method to individual craters under 3 km in diameter remains difficult due to their limited areal extent the ejecta blankets of fresh lunar impact craters are expressed as halos of optical and radar bright material that gradually fade with time although compositional differences make inferring crater ages from optical albedo problematic radar is less sensitive to composition and thus may provide a more reliable means of estimating age in this work we use radar data from the miniature radio frequency mini rf instrument on the lunar reconnaissance orbiter lro to characterize the radar backscatter of large numbers of ejecta blankets by analyzing the size frequency distribution of these craters we show that the lifetime of the radar bright discontinuous ejecta blanket varies with crater diameter in a predictable way for craters with diameters between 0 45 and 5 km absolute ages of individual craters can then be estimated by combining this empirically derived model with estimates of the relative degradation state of each individual crater the lifetimes of radar bright discontinuous ejecta blankets are significantly shorter in the highlands than the maria although this is likely due to local topography creating difficulties in applying the method to the highlands the cosmic ray exposure age of south ray crater a fresh crater visited by apollo 16 provides confirmation of these results this method therefore provides a new way to accurately date small fresh craters using the mini rf data set

biomarker maturity parameters the role of generation and thermal degradation abstract the effects of burial maturation upon seven molecular maturity parameters and the concentrations of individual biomarkers employed in these parameters have been studied in a well in the barents sea the depth interval between 1400 and 3000 m comprises homogenous eocene claystones with effectively uniform organic carbon content 0 4 0 6 and kerogen type hi of 100 200 mg hc g toc the quantitative biomarker data thus contain minimal interference from organic facies hydrocarbon expulsion effects and the presence of migrated hydrocarbons bulk geochemical data define the hydrocarbon generation threshold or oil window at around 2300 m molecular maturity parameters proceed to equilibrium and in some cases demonstrate inversion at high maturity these molecular changes are associated with major changes in biomarker concentrations the hopane 22 s c 31 hopane and 20 s c 29 sterane parameters proceed as a result of the balance between the relative rates of generation and thermal degradation of the different isomers increased concentrations of the individual isomers are interpreted to be the result of biomarker generation from the kerogen mainly and other macromolecular polar fractions the c 29 sterane parameter and the three parameters involving rearranged hopanes ts 29ts and diahopane operate at higher maturity levels and proceed as a result of the relative rates of thermal degradation of the compound pairs isomerisation in the bitumen may also influence the operation of the parameters involving stereoisomers but must be a relatively minor contribution

evidence for water ice on the moon results for anomalous polar craters from the lro mini rf imaging radar 1 the mini rf radar instrument on the lunar reconnaissance orbiter spacecraft mapped both lunar poles in two different rf wavelengths complete mapping at 12 6 cm s band and partial mapping at 4 2 cm x band in two look directions removing much of the ambiguity of previous earth and spacecraft based radar mapping of the moon s polar regions the poles are typical highland terrain showing expected values of radar cross section albedo and circular polarization ratio cpr most fresh craters display high values of cpr in and outside the crater rim the pattern of these cpr distributions is consistent with high levels of wavelength scale surface roughness associated with the presence of block fields impact melt flows and fallback breccia a different class of polar crater exhibits high cpr only in their interiors interiors that are both permanently dark and very cold less than 100 k application of scattering models developed previously suggests that these anomalously high cpr deposits exhibit behavior consistent with the presence of water ice if this interpretation is correct then both poles may contain several hundred million tons of water in the form of relatively clean ice all within the upper couple of meters of the lunar surface the existence of significant water ice deposits enables both long term human habitation of the moon and the creation of a permanent cislunar space transportation system based upon the harvest and use of lunar propellant

hopanoid hydrocarbon maturation by an igneous intrusion abstract the thermal effects of an igneous intrusion 0 9 m thick dyke upon the abundance and composition of hopanes and hopenes are reported for a suite of samples within a single sedimentary horizon a carbonate concretion 1 6 m in diameter from the jurassic dun caan shale member bearreraig bay isle of skye scotland the conventional hopane maturity parameters show normal trends towards the dyke and through the oil window approximately 22 45 cm from the dyke i e 25 50 dyke thickness with the exception of the ts ts tm parameter which shows a progressive fall with increasing maturity until the middle of the oil window when it increases markedly molecular abundances demonstrate that the observed changes in the hopane maturity parameters result from the combined effects of generation presumed to be from kerogen and degradation of individual compounds with isomerization in the free phase being minimal or unimportant the unexpected behaviour of ts ts tm results from the minimal generation of ts compared with tm our data indicate that the ts skeleton is not present in the kerogen and at least under the elevated heating associated with an igneous intrusion may be derived from 18 h 22 29 30 trisnorneohop 13 18 ene in the bitumen thermally induced modifications to hopane carbon number distributions are also reported and show that oil source rock correlations between samples of different maturity must consider the effects of generation degradation of kerogen bound hopanes