hopanoid hydrocarbons and perylene in lake biwa japan sediments environmental control on their abundance and molecular composition abstract we examined the vertical distribution of hopanoid hydrocarbons and perylene in sedimentary sections from lake biwa japan and discuss the results with respect to paleoenvironmental information from around the lake region over the last 120 kyr moretene concentration was high above the sections where fall out events of tephra tephra at occurred ca 30 kyr before present bp this feature suggests that the tephra fall out events created o 2 deficient conditions resulting in high activity of methane producing bacteria and of methanotrophic moretene producing bacteria becoming active above the tephra layer five sections at 10 20 kyr ca 35 kyr ca 70 kyr ca 90 kyr and ca 110 kyr bp exhibited peaks in the ratio of 17 21 22r homohopane to 17 21 22r homohopane hopc 31 the n c 23 n c 31 alkane ratio in these sections was 0 6 0 1 n 49 very low if compared with typical characteristics of n alkanes for a sphagnum peat environment n c 23 n c 31 ca 3 6 bingham et al 2010 we conclude that sphagnum peat may not have been an important contributor of n alkanes over the past 120 kyr comparison with previous pollen records for the lake region suggests that high hopc 31 values may be caused by production of acidic soil from expansion of temperate conifer e g cryptomeria forest under cold and wet climate conditions the abundance of perylene relative to sediment or total organic carbon toc was high in the sections at ca 20 kyr ca 70 kyr and ca 90 kyr bp these sections were approximately in accord with those having a maximum in hopc 31 this concordance indicates that the climatic conditions suitable for the production of perylene quinone in soil surrounding the lake coincided with those for a high hopc 31 ratio thus hopc 31 and perylene toc might be useful as proxies of soil acidity temperature and humidity

magnetotelluric imaging of upper crustal convection plumes beneath the taupo volcanic zone new zealand 1 broadband mt magnetotelluric data were recorded that form an array of measurements at the south eastern margin of the tvz taupo volcanic zone in the central north island of new zealand these array data are used to investigate mechanisms by which the tvz s extraordinarily high heat flux is transported to the surface taken together with seismological data these mt data show compelling evidence that support a model of hydrothermal convection within the brittle upper 6 7 km part of the crust both 2 d and 3 d inversion models of these mt data show vertical low resistivity zones that connect surface geothermal fields to an inferred magmatic heat source that lies below the brittle ductile transition

planetary surface dating from crater size frequency distribution measurements partial resurfacing events and statistical age uncertainty abstract we describe the procedure to fit a cumulative production function polynomial to a partial crater size frequency distribution the technique is of particular use in deriving ages for surfaces which have undergone partial resurfacing events namely erosional or depositional events which have affected a limited diameter range of the crater population we demonstrate its use in obtaining times for both the surface formation and the resurfacing event we give a practical outline of the method for making age measurements from crater counts and how to identify resurfacing effects in the results we discuss the conversion of production function polynomials between common presentations and the statistical uncertainty of the determined ages with respect to the non linear chronology function and a minor refinement of data binning

development of a subvolcanic structure by the interaction of liquid filled cracks abstract the interaction of liquid filled cracks may be an important process for magma accumulation and the development of subvolcanic structures the horizontal interaction was studied through the stress analyses around pressured cracks in various regional stress fields the vertical interaction was studied using gelatin experiments buoyaney driven cracks coalesce more easily than pressure cracks the theory of the three dimensional crack interaction was discussed there are two types of crack interaction the interaction between liquid filled cracks may cause coalescence of cracks the interaction between a liquid filled crack and a solid filled crack never causes coalescence the stress relaxation by ductile or brittle behavior or by the driving out of magma decreases the local stress field generated by the accumulation of magma filled cracks as the regional differential stress increases and the minimum compressive principal stress becomes tensile magma filled cracks become parallel to each other as the supply rate of magma filled cracks becomes relatively large or as the regional differential stress decreases and the minimum compressive stress increases the arrangement of magma filled cracks varies from an offset pattern to a radial one because the local compressive stress field cannot be decreased this process leads to the development of subparallel or radial dikes in two dimensions or a dike sheet complex in three dimensions a large magma chamber such as a sphere or a cylinder is not always necessary for the development of a basaltic volcano in case of the interaction between liquid filled cracks magma filled cracks coalesce easily into one large crack and diminish the local compressive stress field last the theory of the crack interaction is applied to developments of various volcanoes the fissure pattern of hekla volcano iceland is explained in terms of the variation of the stress relaxation the difference in fissure pattern between izu oshima and miyakejima volcanoes japan is interpreted by the variation of the differential stress the local stress balance including the stress relaxation is kept in the developments of etna volcano italy and kilauea volcano hawaii

seismic reflectors beneath the central cones of aso volcano kyushu japan abstract the subsurface structure of aso volcano central kyushu japan has been imaged down to 10 km below sea level and notable features of subsurface structure in the central cones were revealed by a 3 d seismic reflection analysis the 3 d reflection analysis included reflection enhancements and 3 d migration the reflection enhancements and the nmo correction were applied on waveform data from the seismic experiment aso98 the 3 d migration with a kirchhoff integral was processed for 1397 nmo corrected traces to calculate the reflectivity at about 60 000 image points in an approximately 7 km by 7 5 km square region the results of the 3 d migration show that the subsurface structure beneath the central cones can be divided into three parts the western part the eastern part and the northwestern part bright reflectors appear in most of them and a significant discontinuity is inferred the reflector horizon at 2 km below sea level spreads beneath the western and the eastern part and is probably the top surface of the pre aso volcanic rocks or the basement rocks reflection voids appear in the western part and just beneath the active crater the reflector void in the western part implies a hot region and is most probably the known seismic anomalies such as low velocity region or attenuation region another reflector void beneath the active crater can also be associated with a hot region apparently surrounding the conduit system of the current volcanic craters the major discontinuity is located beneath the northwest flank of the central cones this discontinuity divides the northwest region with weak reflectors from other parts the discontinuity may be the trace of the oita kumamoto tectonic line which is the major tectonic line in central kyushu crossing the aso caldera

petrological and geochemical composition of lignite from the d field kolubara basin serbia abstract the upper miocene lignite from the main coal seam in the d field kolubara basin is a typical humic coal with huminite liptinite and inertinite concentrations of up to 83 7 vol 17 2 vol and 15 5 vol respectively in the huminite group textinite and ulminite are the most abundant macerals with variable amounts of densinite and attrinite liptodetrinite and sporinite are the most common macerals of the liptinite group while inertodetrinite is the most abundant maceral of the inertinite group the mineral matter consists mostly of clay minerals the main sources of organic matter were gymnosperms conifers and microbial biomass followed by angiosperms based on composition of saturated and aromatic diterpenoids it has been established that coal forming plants belonged to the gymnosperm families taxodiaceae podocarpaceae cupressaceae araucariaceae phyllocladaceae and pinaceae peatification occurred in neutral to slightly acidic fresh water environment composition and distribution of biomarkers show that diagenetic changes of the organic matter were mainly governed by bacterial activity in a suboxic to oxic environment based on distribution of aromatic diterpenoids a novel diagenetic pathway for transformation of abietane type precursors under suboxic to oxic conditions is proposed variations in compositions of macerals and biomarkers are in concordance with pronounced seasonality during pontian which caused changes in the water level redox conditions during peatification and to some extent vegetation differences in the paleo plant communities

petrological and organic geochemical investigation of recent peats with known environments of deposition abstract a series of recent peat samples from tropical sub tropical and temperate locations were investigated using coal petrographical and organic geochemical techniques maceral and biomarker compositions were examined to see if they correlated or diverged from the known environment of deposition of the peats the proportion of humotelinite was related to the water depth and the frequency of dry periods the ph and trophic level have a modifying influence on the preservation of tissues furthermore the proportions of sclerotinite in the peats seem to reflected the oxygen status in the mire which was also mirrored in the abundance of humic and fulvic acids a facies diagram was calculated for the peat samples to see how maceral indices would fare in interpreting their known environments of deposition the results proved to be generally unsuccessful as the herbaceous and woody peats did not always give the predicted high humodetrinite and humotelinite compositions respectively the aliphatic hydrocarbon fraction from the extracts of the peat samples show that mainly odd numbered n alkanes are present diterpenoids triterpenoids and hopanoids were found in most samples and were mainly unsaturated in nature the relative proportion of hopanoids in pears appears to be related to bacterial activity in acidic environments de a triterpenoids were also detected in the peat stage of diagenesis in an angiosperm dominated peat type mariscus polycyclic aromatic triterpenoids were present in the aromatic fraction of the extract their occurrence and proportion appears to be related to the degree of humification in a taxodium peat mono di and triaromatic diterpenoids were detected the presence of these aromatic biomarkers indicate the rapid formation of these compounds in the peat stage mainly mediated by microbial activity

the microbial input in carbonate anhydrite facies of a sabkha palaeoenvironment from guatemala a molecular approach abstract nine representative rock samplesincluding four anhydrites an oil stained dolomite and a laminated mudstone source rock from a sabkha type palaeoenvironment la felicidad 1 well guatemala have been compared in order to tentatively characterize each facies by a geochemical signature each sample has been studied by using basic parameters toc rock eval pyrolysis yields and analyses of alkanes and aromatics by computerized gc ms the following families of compounds have been reviewed n alkanes branched and cyclic alkanes n alkylbenzenes benzohopanes monoaromatic steroids d ring aromatic 8 14 secohopanoids alkylnaphthalenes alkylphenanthrenes alkyldibenzothiophenes and triaromatic steroids despite close geochemical relationships of all the sample a more in depth investigation taking into account molecular patterns and semi quantitative data reveals significant differences among the samples anhydrites may be differentiated from carbonates which illustrates the efficiency of organic geochemistry in environmental palaeoreconstruction even in organiccarbon lean sediments toc 0 04 0 08 in anhydrites in these anoxic marginally mature sediments the strong predominance of triterpanes over steranes tt to st 20 associated with other molecular features leads to the conclusion that the main contribution to the organic matter of all facies is by bacteria several prominent components including novel families iso c23 and iso c27 alkanes tetracyclic terpanes d ring aromatic 8 14 secohopanoids 1 phenylpentadecane undecylnaphathalene and their mono and dimethylated counterparts have been interpreted as derived from halophilic bacteria these conclusions may be extended to all crude oils from the same area which may be considered as true bacterially derived petroleums the la felicidad 1 well data are discussed with reference to other palaeosabkha type sequences from the sw aquitaine basin france in which the bacterial input is less important however in these sabkha sequences 1 phenylpentadecane undecylnaphthalene and related structures have also been identified

changes in bulk properties and molecular compositions within new zealand coal band solvent extracts from early diagenetic to catagenetic maturity levels abstract the bulk properties and bitumen molecular compositions of a rank series of 38 humic coals from the new zealand coal band cretaceous cenozoic have been analysed to investigate early maturation processes affecting coaly organic matter through diagenesis to moderate catagenesis rank s r 0 0 11 8 r o 0 23 0 81 the samples comprise a relatively restricted range of vitrinite rich coal types formed largely from higher land plant material under relatively oxic conditions but with a significant contribution from microbial biomass with increasing rank total organic carbon contents show a general increase whereas moisture and asphaltene contents decrease bitumen yields also decrease through the stages of diagenesis and early catagenesis rank s r r o r 5 6 r o 0 40 as indicated by the constant occurrence and gradual increase of isoprenoids e g pristane and phytane and hopanoids in their more mature configuration this early phase of catagenesis not previously recognised in new zealand coals is followed at rank s r 9 r o 0 55 by the main catagenesis phase characterised by a more rapid increase in the generation of hydrocarbons including total n alkanes isoprenoids and hopanes changes in the maturity of new zealand coals can be traced by the carbon preference index and several hopane maturity parameters including 22 s 22 s 22 r and

recent sedimentary hopanoids in the northwestern pacific alongside the japanese islands their concentrations and carbon isotopic compositions two hopanoids 17b h 21b h hop 22 29 ene diploptene and 17b h 21b h bishomohopanoic acid bbc32ha are the most abundant among the pentacyclic triterpenoids found in recent sediments of the pacific ocean alongside the japanese islands the concentration of diploptene normalized to organic carbon content is higher in sediments where c37 polyunsaturated alkene a biomarker of haptophytes is in high concentration suggesting that the diploptene may be associated with the accumulation of marine organic matter in open marine settings d 13 c values of bbc32 ha range from 23 8 to 19 4 relative to pdb being enriched in 13 c relative to diploptene 31 6 to 26 3 by 5 9 the isotopic diaerence indicates the presence of at least partially diaerent sources for the two hopanoids while diploptene is derived from cyanobacteria and chemotrophic bacteria in the water column or sediment bishomohopanoic acid may be produced mainly by heterotrophs in the sediment using marine organic matter in contrast the d 13 c values of the two hopanoids from river and bay sediments are similar 31 to 29 indicating a common source derived from soil components terrestrial plants or bacteria in soils 2000 elsevier science ltd all rights reserved

martian landslides in valles marineris wet or dry the objective of this paper is to determine whether martian landslides in valles marineris were wet or dry and place constraints on the availability of liquid water in valles marineris during the amazonian when the landslides occurred we thus statistically compare the power law relationship between the volume and runout distance of landslides on earth with those in valles marineris mars the exponent of the power law for martian landslides is similar to that for dry landslides and volcanic flows on earth and differs significantly from wet debris flows on earth the constant of proportionality in the observed power law relationship for martian flows is linearly proportional to gravity as predicted from physical modeling of dry flows in which the dissipation occurs in a layer of uniform thickness conversion of gravitational potential energy to heat is insufficient to generate more than a few weight percent of liquid water in the landslide we thus conclude that water did not significantly influence the dynamics of landslides in valles marineris this implies predominantly dry conditions in valles marineris during the amazonian

atmospheric origin of martian interior layered deposits links to climate change and the global sulfur cycle since the first photogeologic exploration of mars vast mounds of layered sediments found within the valles marineris troughs interior layered deposits ilds have remained unexplained recent spectroscopic results showing that these materials contain coarse grained hematite and sulfate suggest that they are fundamentally similar to layered sulfate deposits seen elsewhere on mars and are therefore a key piece of the global aqueous history of mars in this work we constrain the origin of the ilds by considering mass balance equations one model involving formation of the ilds by groundwater upwelling requires that a significant fraction of the global martian sulfur budget was concentrated in the valles marineris at the time when the ilds formed it also necessitates high deposition and erosion rates in the hesperian we favor an alternative model in which the ilds formed in a configuration similar to what is observed today through atmospherically driven deposition of ice dust and volcanogenic sulfuric acid such a model is easily compatible with the global sulfur budget and does not require significant erosion rates or large volumes of liquid water we propose that formation of sulfate rich layered sediments on mars was governed through time by volcanogenic so 2 and h 2 o emission rates and dust production against a backdrop of obliquity variation in a largely cold and dry climate

wind as the primary driver of erosion in the qaidam basin china deserts are a major source of loess and may undergo substantial wind erosion as evidenced by yardang fields deflation pans and wind scoured bedrock landscapes however there are few quantitative estimates of bedrock removal by wind abrasion and deflation here we report wind erosion rates in the western qaidam basin in central china based on measurements of cosmogenic 10 be in exhumed miocene sedimentary bedrock sedimentary bedrock erosion rates range from 0 05 to 0 4 mm yr although the majority of measurements cluster at 0 12570 05 mm yr these results combined with previous work indicate that strong winds hyper aridity exposure of friable neogene strata and ongoing rock deformation and uplift in the western qaidam basin have created an environment where wind instead of water is the dominant agent of erosion and sediment transport its geographic location upwind combined with volumetric estimates suggest that the qaidam basin is a major source up to 50 of dust to the chinese loess plateau to the east the cosmogenically derived wind erosion rates are within the range of erosion rates determined from glacial and fluvial dominated landscapes worldwide exemplifying the effectiveness of wind to erode and transport significant quantities of bedrock

subtidal stromatolites in monterey formation and other organic rich rocks as suggested source contributors to petroleum formation the miocene monterey formation contains thin organic rich laminations that mimic benthic mats forming today in coastal upwelling regimes of the eastern pacific modern mats are comprised dominantly of filamentous sulfur oxidizing bacteria of the family beggiatoaceae the characteristic spongy texture imparted to the sediments by these bacterial mats is most readily recognized using scanning electron microscopy sem the spongy network becomes progressively compressed with increasing compaction and diagenesis but is still distinguishable rock eval pyrolysis of modern mats reveals high s1 peaks and unusually high oxygen indices both parameters decrease gradually with diagenesis as evidenced by mat laminated monterey formation samples of different thermal grades in addition anomalously light nitrogen isotopic signatures of modern mats may be retained the dgrn15 values of mat laminated monterey formation samples although diagenetically enriched in 15n are still lighter than would be expected for algally dominated organic matter in marine low oxygen environments on the basis of organic richness and high hydrogen indices of mat laminated samples and coincidence of mat laminated rocks and oil in some fields in the san joaquin valley of california the organic matter assemblage contained within filamentous bacterial mats is suggested to be a significant contributor to petroleum formation additional evidence for this conclusion is provided by similar investigations of subtidal cyanobacterial mats in carbonate rocks such as the green river formation oil shales

mars sedimentary rock erosion rates constrained using crater counts with applications to organic matter preservation and to the global dust cycle abstract small crater counts on mars light toned sedimentary rock are often inconsistent with any isochron these data are usually plotted then ignored we show using an 18 hirise image 104 crater dataset that these non isochron crater counts are often well fit by a model where crater production is balanced by crater obliteration via steady exhumation for these regions we fit erosion rates we infer that mars light toned sedimentary rocks typically erode at 102 nm yr when averaged over 10 km2 scales and 107 108 yr timescales crater based erosion rate determination is consistent with independent techniques but can be applied to nearly all light toned sedimentary rocks on mars erosion is swift enough that radiolysis cannot destroy complex organic matter at some locations e g paleolake deposits at sw melas but radiolysis is a severe problem at other locations e g oxia planum the data suggest that the relief of the valles marineris mounds is currently being reduced by wind erosion and that dust production on mars

exceptional preservation of hopanoid and steroid biomarkers in ediacaran sedimentary rocks of the east european craton abstract thermally unstable hopanes with a biological 17 21 h configuration hopanes hopenes hopanoic acids and hopanols were identified as important constituents of ediacaran to cambrian sedimentary rocks of the east european craton relatively high abundances of hopanes in relation to hopanes were identified in the petersburg area and eastern belarus while in volyn samples these compounds were found in traces in addition polar hopanoids including hopanols and hopanoic acids were found in most of the petersburg and some belarus and volyn sedimentary rocks the estimated equivalent of vitrinite reflectance for samples of lower maturity measured based on c31 s r ratio is in the range 0 28 0 49 rr while for those of higher thermal maturity this parameter corresponds to 0 41 0 57 rr the values of the c31 22s s r ratio are in agreement with above data and are in the range of 0 1 0 3 for the belarus and petersburg samples of 0 3 0 4 for volyn and of 0 4 0 5 for lithuania where hopanes and hopanols were not detected or are present as traces moreover there is good correlation r2 0 8 between c31 s r and c31ene h ene ratio values defined as ratio of c31 hopenes to hopanes which proves that less stable hopanes and hopenes are enriched in the same immature sedimentary rocks the remarkable occurrence of a significant portion of sedimentary hopanes retaining the biological stereochemical configuration confirms that exceptionally immature precambrian rocks can be found in some instances when these strata have undergone only a mild burial temperature history

small crater modification on meridiani planum and implications for erosion rates and climate change on mars a morphometric and morphologic catalog of 100 small craters imaged by the opportunity rover over the 33 5 km traverse between eagle and endeavour craters on meridiani planum shows craters in six stages of degradation that range from fresh and blocky to eroded and shallow depressions ringed by planed off rim blocks the age of each morphologic class from 50 200 ka to 20 ma has been determined from the size frequency distribution of craters in the catalog the retention age of small craters on meridiani planum and the age of the latest phase of ripple migration the rate of degradation of the craters has been determined from crater depth rim height and ejecta removal over the class age these rates show a rapid decrease from 1 m myr for craters 1 ma to 0 1 m myr for craters 10 20 ma which can be explained by topographic diffusion with modeled diffusivities of 10 6 m2 yr in contrast to these relatively fast short term erosion rates previously estimated average erosion rates on mars over 100 myr and 3 gyr timescales from the amazonian and hesperian are of order 0 01 m myr which is 3 4 orders of magnitude slower than typical terrestrial rates erosion rates during the middle late noachian averaged over 250 myr and 700 myr intervals are around 1 m myr comparable to slow terrestrial erosion rates calculated over similar timescales this argues for a wet climate before 3 ga in which liquid water was the erosional agent followed by a dry environment dominated by slow eolian erosion

geochemical and biological marker assessment of depositional environments using brazilian offshore oils abstract a combined geochemical and molecular characterization of a wide selection of oils from the major brazilian offshore basins has been undertaken the elemental sulphur nickel and vanadium and bulk oapi and 13c properties of each sample been considered together with its molecular composition determined using liquid and gas chromatography and quantitative biological marker investigations using gas chromatography mass spectrometry for alkanes the results reveal significant differences in the chemical features of the various oils which enable them to be divided into five groups the distinction of the groups appears to reflect differences in the depositional environment of the source rocks of the oils each group is correlated tentatively with source rocks laid down in a specific depositional regime namely lacustrine freshwater lacustrine saline water marine evaporitic marine carbonate or marine deltaic the diagnostic features that allow this classification are the relative abundance and carbon number distributions of n alkanes pristane phytane ratios sulphur nickel and vanadium contents carbon isotope data the absolute concentrations of hopanes and steranes and their abundance relative to 4 methylsteranes and also the occurrence and abundance of several specific biological markers including 18 h oleanane gammacerane carotane tricyclic terpanes higher acyclic isoprenoids 28 30 bisnorhopane and 25 28 30 trisnorhopane this investigation shows the value of a combined geochemical and molecular approach in the assessment of the palaeoenvironment of deposition of the source rocks which gave rise to the oils

changes in the global carbon cycle occurred as two episodes during the permian triassic crisis coeval records of ocean atmosphere and terrestrial change are crucial to understanding the pattern and causes of global mass extinction across the permian triassic boundary ptb however relationships among changes in different settings remain largely unclear primarily due to the challenges associated with the correlation among disparate records here we compare marine carbon isotopic records with marine and terrestrial environmental and biotic events recorded in sediments from the meishan ptb section of south china time scaled carbonate carbon isotopes exhibit two gradual major shifts across the ptb at meishan and these are duplicable elsewhere around the tethys ocean the two shifts are associated with two episodes of enhanced terrestrial weathering indicated by an increased abundance of 13 c enriched moretanes relative to hopanes and an elevated abundance of black carbon fragments key marine events previously reported for the ptb including photic zone euxinia faunal mass extinction and cyanobacterial expansion also occur as two episodes coinciding with both of the progressive shifts to negative 13 c values and enhanced weathering the temporal sequence of the duplicable events suggests that the biotic crisis was a consequence of prolonged and episodic changes in the marine and continental systems and argues against an extraterrestrial impact as the main cause

unusual distributions of long chain n alkanes and n alkenes in antarctic soil abstract hydrocarbons in soil samples from the mcmurdo dry valleys of southern victoria land antarctica were studied to examine their features and to elucidate source materials normal alkanes and n alkenes were found at concentrations ranging from 13 to 2200 and from 1 1 to 5000 ng g of dry soil respectively unexpectedly the major hydrocarbons were all odd carbon numbered long chain n alkanes with maximum concentrations n c 23 n c 25 or n c 27 this may be due to the erosion of sedimentary materials containing vascular plant debris formed during the pre and inter glaciation periods of antarctica miocene pliocene and microbial debris such as fungi and microalgae normal alkenes maximize at n c 23 1 carbon chain length number of double bonds n c 25 1 n c 27 1 or n c 29 2 which could be derived from cyanobacteria and microalgae that lived in the past in the antarctic cold desert and or organic debris of wind transported cyanobacterial mats

global scale analysis of martian landslide mobility and paleoenvironmental clues the mobility of landslides on mars is studied based on a database of 3 118 events to establish the volume of the landslides for the whole dataset based on the deposit area a new volume area relationship based on a representative dataset of 222 landslides is used plotting the h l ratio between fall height h and runout l versus volume landslide mobility is analyzed and compared with existing empirical relationships for martian and terrestrial landslides analyzing the mobility in terms of normalized residuals i e the relative deviation of the h l ratio from the dataset best fit line mobility is found to depend on both the landslide location on mars and landslide typology this allows us to identify four different types of high mobility hypermobile landslides three classes of high mobility landslides are associated respectively to meteoroid impact the olympus mons aureoles and landslides with toreva block failure style and their mobility can be explained by the peculiar flow mechanics the fourth class includes landslides associated with isolated craters those in the regions wetted by the putative oceanus borealis and the ones at high latitudes we suggest that the common factor behind all the hypermobile landslides of this fourth kind is the presence of ice this is confirmed by our data showing that landslides increase in mobility with latitude the latitudinal trend mirrors the distribution of ice as detected by radar neutron probes and the presence of glacial and layered ejecta morphologies because the overall landslide distribution supports the presence of ice lubricated conditions two ice lubrication models are presented showing how ice melting within or underneath the landslides could enhance mobility by proper analysis in terms of apparent friction residuals we find that the mobility of landslides in valles marineris with the largest landslide concentration is lower than average we explain this circumstance partly from the smaller role of ice in equatorial valles marineris and partly because the collapses from high slope relief imply high speed impact with the floor valley confinement loss of momentum and decrease in mobility environmental consequences imply that the present subsurface ice distribution may have been persistent throughout the amazonian period

scoria cones on mars detailed investigation of morphometry based on high resolution digital elevation models we analyze the shapes of 28 hypothesized scoria cones in three regions on mars i e ulysses and hydraotes colles and coprates chasma using available high resolution imaging science experiment and context camera ctx digital elevation models we determine the basic morphometric characteristics of the cones and estimate from ballistic modeling the physical parameters of volcanic eruptions that could have formed them when compared to terrestrial scoria cones most of the studied cones show larger volumes up to 4 2 109m3 larger heights up to 573m and smaller average slopes the average slopes of the ulysses hydraotes and coprates cones range between 7 and 25 and the maximum slopes only rarely exceed 30 which suggests only a minor role of scoria redistribution by avalanching ballistic analysis indicates that all cones were formed in a similar way and their shapes are consistent with an ejection velocity about 2 times larger and a particle size about 20 times smaller than on earth our results support the hypothesis that the investigated edifices were formed by low energy strombolian volcanic eruptions and hence are equivalent to terrestrial scoria cones the cones in hydraotes colles and coprates chasma are on average smaller and steeper than the cones in ulysses colles which is likely due to the difference in topographic elevation and the associated difference in atmospheric pressure this study provides the expected morphometric characteristics of martian scoria cones which can be used to identify landforms consistent with this type of activity elsewhere on mars and distinguish them from other conical edifices

topography of valles marineris implications for erosional and structural history compilation of a simplified geologic geomorphic map onto digital terrain models of the valles marineris permitted an evaluation of elevations in the vicinity of the troughs and the calculation of depth of troughs below surrounding plateaus thickness of deposits inside the troughs volumes of void spaces above geologic geomorphic units and volumes of deposits the central troughs north ophir north and central candor and north melas chasmata lie as much as 11 km below the adjacent plateaus in ophir and candor chasmata interior layered deposits reach 8 km in elevation if the deposits are lacustrine and if all troughs were interconnected lake waters standing 8 km high would have spilled out of coprates chasma onto the surrounding plateaus having surface elevations of only 4 5 km in this case interior deposits above about 4 km in the central troughs would not be lacustrine they could be volcanic on the other hand the troughs may not have been interconnected at the time of interior deposit emplacement they may have formed isolated ancestral basins the existence of such basins is supported by independent structural and stratigraphic evidence the ancestral basins may have eventually merged perhaps through renewed faulting to form northern subsidiary troughs in ophir and candor chasmata and the coprates north melas ius graben system the peripheral troughs are only 2 5 km deep shallower than the central troughs they may have formed from a combination of erosional collapse and structural activity chaotic terrain is seen in the peripheral troughs near a common contour level of about 4 km on the adjacent plateaus which supports the idea of release of water under artesian pressure from confined aquifers the layered deposits in the peripheral troughs may have formed in isolated depressions that harbored lakes and predated the formation of the deep outflow channels if these layered deposits are of volcanic origin they may have been emplaced beneath ice in the manner of table mountains areal and volumetric computations show that erosion widened the troughs by about one third and that deposits occupy one sixth of the interior space even though the volume eroded is larger than the volume deposited topographic and geologic considerations imply that material eroded from trough walls was probably part of the interior layered deposits but not their sole source additional material may have come from subterranean piping from reworking of local disintegration products on the floors such as chaotic materials or from eolian influx but overall it is likely that the additional material is volcanic and that it forms mostly the upper more diversely bedded layers of the interior deposits

the light toned stratified sedimentary rock exposures in western juventae chasma mars in context abstract juventae chasma an isolated depression northeast of the valles marineris trough system hosts four mounds of light toned layered materials these are erosional remnants interpreted to consist of sedimentary rocks the geological setting of juventae chasma is a complex amalgamation of terrains and surfaces of different morphologies ages and structures most previous published studies assumed or interpreted that the light toned mound forming materials were deposited in the chasm after it opened or began to open here we use detailed observations of the geologic setting the nature of chasm wall rocks and the distribution and nature of the contacts of the light toned materials with adjacent geologic materials to argue that the light toned mounds in juventae chasma are more likely remnants of light toned materials that existed in the subsurface before the chasm opened up the rock cut by the chasm was not a monolithic unit e g lava flows and might have included both light toned and dark toned sedimentary rocks bearing a range of diagenetic properties the light toned materials were deposited as clasts precipitates or both within craters or depressions that were filled buried lithified and then exposed when juventae chasma formed because the sedimentary rock types and stratal package properties differ from one mound to the next the buried craters or depressions could have existed at different times and provide sedimentary records of different environments that existed at different times during the planet s early history noachian period upon exposure these materials as well as chasm wall rocks and chaotic terrain blocks underwent differential erosion as a function of rock physical properties to produce the geomorphic expressions observed today

distribution of polar membrane lipids in permafrost soils and sediments of a small high arctic catchment the distribution of bacteriohopanepolyols bhps and intact polar membrane lipids ipls was studied in different soil profiles and in fluvial and marine sediments along the pathway of transport in a small catchment in the high arctic at ny alesund svalbard 79 n 12 e both groups of cellular membrane lipids have been used as biomarkers for determining major microbial groups and biogeochemical processes in natural environments little is known about their distribution and usefulness as environmental markers in the arctic in this study we show that both membrane lipid groups are variably distributed in the drainage area of the broggerbreen glacier with highest abundance and diversity in the organic mat overlying the mineral soils as well as in mossy surface soil the bhp and ipl composition and abundance both indicate a larger community of phototrophic bacteria in the organic mats and fluvial sediments the greater diversity and abundance of bhps relative to ipls in sub soils including probable markers for cyanobacteria suggest a greater resistance to degradation in contrast ipl concentration decreased strongly with soil depth pointing to their rapid degradation bacterial ipls are thus thought to reflect more reliably the biomass of viable phototrophic bacteria the high concentrations of proposed soil marker bhps adenosylhopane and related structures vs published results and their relative increase with soil depth suggest better preservation and more effective accumulation of the compounds at low temperature

paleoreconstruction by biological markers abstract during diagenesis and conversion of the original lipid fraction of biological systems to petroleum hydrocarbons the following four basic events needed for paleoreconstruction can be monitored by biological markets 1 sourcing 2 maturation 3 migration and 4 biodegradation actual cases of applying biological markers to petroleum exploration problems in different parts of the world are demonstrated cretaceous and phosphoria sourced oils in the wyoming thrust belt can clearly be distinguished from one another by high quality source fingerprinting of biomarker terpanes using gas chromatography mass spectrometry identification of recently discovered biological markers head to head isoprenoids allows subtle source differentiation between oils from sumatra the degree of crude oil maturation in basins from california alaska russia wyoming and louisiana can be assessed by specific novel biomarker ratios 20s 20r sterane epimers field evidence from such interpretation is confirmed by laboratory pyrolysis of the rock an example of immature sumatra rock is given extensive migration is documented by biomarkers in several oils the effect of biodegradation on biomarker steranes and terpanes is exemlified in a california basin all biological marker results are consistent with the geological setting and add a new dimension in assisting the petroleum explorationist toward paleo reconstruction

an integrated biomarker isotopic and palaeoenvironmental study through the late permian event at lusitaniadalen spitsbergen abstract the largest extinction of the phanerozoic occurred near the permian triassic p tr boundary some 252 ma ago several scenarios and drivers have been proposed for this event here we report for the first time an integrated study comprising sedimentological data biomarker distributions abundances and selected stable carbon and hydrogen isotopes along with bulk isotopes 34spyrite 13ccarb 13corg for a late permian section from lusitaniadalen spitsbergen norway sedimentological and geochemical data support a marine transgression and collapse of the marine ecosystem in the late permian strong evidence for waxing and waning of photic zone euxinia throughout the late permian is provided by chlorobiaceae derived biomarkers including 13c data and 34spyrite implying multiple phases of h2s outgassing and potentially several pulses of extinction a rapid decrease in abundance of various land plant biomarkers prior to the marine collapse event indicates a dramatic decline of land plants during the late permian and or increasing distance from palaeoshoreline as a consequence of sea level rise changes in d of selected biomarkers also suggest a change in source of organic matter om or sea level rise we also found biomarker and isotopic evidence for a phytoplanktonic bloom triggered by eutrophication as a consequence of the marine collapse compound specific isotope analyses csia of algal and land plant derived biomarkers as well as 13c of carbonate and bulk om provide strong evidence for synchronous changes in 13c of marine and atmospheric co2 attributed to a 13c depleted source the source could be associated with isotopically depleted methane released from the melting of gas clathrates and or from respired om due to collapse of the marine ecosystem

earth like sand fluxes on mars strong and sustained winds on mars have been considered rare on the basis of surface meteorology measurements and global circulation models raising the question of whether the abundant dunes and evidence for wind erosion seen on the planet are a current process recent studies showed sand activity but could not determine whether entire dunes were moving implying large sand fluxes or whether more localized and surficial changes had occurred here we present measurements of the migration rate of sand ripples and dune lee fronts at the nili patera dune field we show that the dunes are near steady state with their entire volumes composed of mobile sand the dunes have unexpectedly high sand fluxes similar for example to those in victoria valley antarctica implying that rates of landscape modification on mars and earth are similar

structural development of coprates chasma and western ophir planum valles marineris rift mars a portion of valles marineris was mapped in detail in order to clarify the dominant processes responsible for the formation of coprates chasma new crater counts indicate that the caprock on western ophir planum plateau has a late hesperian crater age whereas trough floor preserved in western coprates chasma has an early to late hesperian crater age caprock on western ophir planum correlates in relative age with the syria planum formation and the caprock may overlie lower hesperian ridged plains material the conspicuous absence of wrinkle ridges on ophir planum may reflect burial by this later material trough floor material in coprates chasma correlates in relative age with ridged plains material on the adjacent lunae planum and coprates plateaus and represents a structurally coherent block displaced downward by normal faulting the crater counts and detailed structural relationships demonstrate the commonly accepted view that coprates chasma occupies a graben the floor of this graben is only thinly mantled by intratrough deposits and is relatively intact the trough shows no evidence for a chaotically broken and jumbled floor as required by genesis models of collapse and subsurface drainage formation of coprates chasma by keystone collapse of locally elevated topography is not supported by available topographic data but a general association between the trough and volcanotectonic activity in the tharsis region is considered to be a likely explanation for the trough forming stresses subtle asymmetries in topography and boundary fault development across coprates chasma may imply a gentle down to the north half graben geometry for the trough normal faults that define the northern margin of western coprates chasma and those that deform the adjacent ophir planum plateau change trend systematically with position implying a 30 rotation of the local horizontal principal stresses in this region during trough growth faulting on ophir planum appears related to the faulting that created the coprates chasma trough the geology and structure of coprates chasma are comparable to those of other troughs such as melas ius and perhaps candor chasmata suggesting that these troughs may also have formed as grabens the revised crater age for western ophir planum indicates that the initiation of trough faulting and subsidence in the valles marineris system is early late hesperian and may have been synchronous across the system relative to the prevailing cratering rate

hopane derived triterpenoids in soils the occurrence distribution and degradation pathways of hopanoid triterpenes have been studied in thirteen soil samples with varying degrees of biological activity hopanoids were shown to occur in all samples suggesting that they are not only ubiquitous in subaquatic sediments but also in soils hop 22 29 ene was generally predominant in the hydrocarbons whereas the 17 h 21 h bishomohopanoic acid c32 was the major component in the acids the concentrations of hopanes were usually rather low except in acidic peat the distribution in carbon number of hopanes and hopanoic acids showed great similarities with those of moderately oxic subaquatic sediments intact bacteriohopane tetrol widespread in microorganisms and the main precursor of geohopanoids was identified in substantial amounts in a peat exposed to groundwater oscillations

vertical evolution of petrographic and organic geochemical parameters in las duenas mire cantabrian coast north spain abstract las duenas mire has developed on a flat siliceous substrate over the holocene the sedimentary cover has a thickness of around 50 cm and the mire comprises a surface area of 27 ha a core sample obtained using a manual probe was split into sub samples of around 3 4 cm thickness for petrographic and organic geochemical analysis the fen originated by minerogenesis and contains a high concentration of mineral matter throughout its profile which decreases towards the top the present day vegetation is dominated by sphagnum a variety of transparent textinite with intense fluorescence is evidence of the low maturity of the profile which is also confirmed by the presence of low reflecting huminite of the a variety hr 0 15 the fluorescence spectra of sporinite and cutinite are similar and compared with those of transparent textinite they have a lower intensity and are shifted to higher wavelengths the low maturity of the organic matter is also confirmed by the presence of unstable hopane configurations the abundance of hopene and the presence of functionalized hopanoids steroids and other triterpenoids the evolution of the geochemical parameters in the peat profile indicates the presence of more humid conditions in the top 4 cm and at a depth of 11 15 cm these periods are characterized by a high sphagnum higher plant contribution as deduced from the n alkane ratios the low reflectance of huminite at the depth of 11 15 cm could also support less oxidizing condition the sediment at a depth of 22 cm where peaty matter starts to accumulate has been dated as 9603 cal bc whereas the plant fraction at the same depth dates back to a maximum of 200 years sediment reworking derived from radiocarbon dates indicates that this fen is not suitable for palaeoenvironmental studies

microbial lipid markers within and adjacent to challenger mound in the belgica carbonate mound province porcupine basin offshore ireland iodp expedition 307 abstract during the integrated ocean drilling program iodp expedition 307 for the first time a cold water coral carbonate mound was drilled down through its base into the underlying sediments in the current study sample material from within and below challenger mound located in the belgica carbonate mound province in the porcupine basin offshore ireland was investigated for its distribution of microbial communities and gas composition using biogeochemical and geochemical approaches to elucidate the question on the initiation of carbonate mounds past and living microbial populations are lower in the mound section compared to the underlying sediments or sediments of an upslope reference site a reason for this might be a reduced substrate feedstock reflected by low total organic carbon toc contents in the once coral dominated mound sequence in contrast in the reference site a lithostratigraphic sequence with comparatively high toc contents shows higher abundances of both past and present microbial communities indicating favourable living conditions from time of sedimentation until today composition and isotopic values of gases below the mound base seem to point to a mixed gas of biogenic and thermogenic origin with a higher proportion of biogenic gas oil derived hydrocarbons were not detected at the mound site this suggests that at least in the investigated part of the mound base the upward flow of fossil hydrocarbons being one hypothesis for the initiation of the formation of carbonate mounds seems to be only of minor significance

hypotheses for the origin of the hypanis fan shaped deposit at the edge of the chryse escarpment mars is it a delta abstract we investigated the origin of the fan shaped deposit at the end of hypanis valles that has previously been proposed as an exomars mars 2020 and human mission candidate landing site and found evidence that the landform is an ancient delta previous work suggests that the deposit originated from a time of fluvial activity both distinct from and prior to catastrophic outflow and crater counting placed the deposit s age at 3 6 ga we found over 30 thin sedimentary strata in the proposed delta wall and from our slope analysis conclude that the fluvial sequence is consistent with a lowering retreating shoreline we measured nearly horizontal bedding dip angles ranging from 0 to 2 over long stretches of cliff and bench exposures seen in hirise images and hirise stereo dtms from themis night ir images we determined that the fan shaped deposit has a low thermal inertia 150 240 jm 2k 1s 1 2 and the surrounding darker toned units correspond to thermal inertia values as high as 270 390 jm 2k 1s 1 2 we interpret these findings to indicate that the fan shaped deposit consists mostly of silt sized and possibly finer grains and that the extremely low grade and large lateral extent of these beds implies that the depositional environment was calm and relatively long lived our assessment of the geomorphology and composition seems to indicate that the alluvial fan and mudflow hypotheses are less compatible from our stratigraphic mapping we interpret the order of events which shaped the region after the chryse impact sediment filled the basin a confined lake or sea formed allowing a large delta to be deposited near its shoreline the water level receded to the north darker sedimentary volcanic units covered the region and capped the light toned deposit as hydro volcanic eruptions shaped the interior of lederberg crater freeze thaw cycles and desiccation induced local fracturing and finally wrinkle ridges associated with rounded cones warped the landscape following trends in degraded crater rims and existing tectonic features the ancient deltaic deposit we observe today was largely untouched by subsequent catastrophic outflows and its surface has been only moderately reshaped by over 3 billion years of aeolian erosion

repeated large scale eruptions from a single compositionally stratified magma chamber an example from aso volcano southwest japan abstract aso volcano has the largest caldera 18 25 km in the southwestern japan island arc which was formed as a result of four gigantic pyroclastic eruption cycles the latest eruption cycle aso 4 cycle 90 ka produced the most voluminous deposits 600 km3 among the four eruption cycles we investigated pre eruptive magma chamber configurations and processes in compositionally stratified aso 4 pyroclastic eruptions based on whole rock chemical phenocryst mineralogical and sr isotope analyses of juvenile clasts previous stratigraphical studies have suggested that the aso 4 cycle is divided into two subcycles in both of which eruption of voluminous silicic is followed by eruption of mafic magma geochemical and mineralogical results indicate that the pre eruptive magma chamber was composed of three layers silicic hybrid and mafic magma layers from the top to the bottom the silicic magma layer was relatively homogenous whereas the mafic magma layer was compositionally zoned where magma became more silicic with height the hybrid magma was generated by mixing the silicic magma and the silicic end of the zoned mafic magma layer i e the uppermost part of the mafic magma layer the first subcycle began with evacuation of the upper silicic magma and successively proceeded to tap the lower hybrid and mafic magmas the eruption of the first subcycle stopped before the whole magma chamber evacuated during this subcycle the hybrid magma and the upper part of the mafic magmas layer were selectively withdrawn and mixed with the overlying silicic magma the second subcycle eruption started with the new hybrid magma and followed by eruption of the mafic magma

pore pressure embrittlement in a volcanic edifice the failure mode of porous rock in compression dilatant or compactant is largely governed by the overlying lithostatic pressure and the pressure of pore fluids within the rock wong solid earth 102 3009 3025 1997 both of which are subject to change in space and time within a volcanic edifice while lithostatic pressure will tend to increase monotonously with depth due to the progressive accumulation of erupted products pore pressures are prone to fluctuations during periods of volcanic unrest for example an increase in pore fluid pressure can result in rock fracture even at depths where the lithostatic pressure would otherwise preclude such dilatant behaviour a process termed pore fluid induced embrittlement we explore this phenomenon through a series of targeted triaxial experiments on typical edifice forming andesites from volcan de colima mexico we first show that increasing pore pressure over a range of timescales on the order of 1 min to 1 day can culminate in brittle failure of otherwise intact rock irrespective of the pore pressure increase rate we record comparable accelerations in acoustic emission and strain prior to macroscopic failure we further show that oscillating pore fluid pressures can cause iterative and cumulative damage ultimately resulting in brittle failure under relatively low effective mean stress conditions we find that macroscopic failure occurs once a critical threshold of damage is surpassed suggesting that only small increases in pore pressure may be necessary to trigger failure in previously damaged rocks finally we observe that inelastic compaction of volcanic rock as we may expect in much of the deep edifice can be overprinted by shear fractures due to this mechanism of embrittlement pore fluid induced embrittlement of edifice rock during volcanic unrest is anticipated to be highest closer to the conduit and as a result may assist in the development of a fractured halo zone surrounding the conduit potentially explaining commonly observed near conduit outgassing at many active volcanoes further rock embrittlement at depth may create transient outgassing pathways by linking fracture networks near the edifice to larger scale regional fault systems our experimental results affirm that pore pressure fluctuations associated with volcanic unrest may play a crucial role in dictating the evolution of a volcanic system

environmental influence on the biohopanoid composition of recent sediments abstract bacteriohopanepolyols are the biological precursors of extended hopane biomarkers which are ubiquitous in the geosphere the abundance and composition of these biohopanoids were determined for modern sediments from eight depositional environments by gc ms analysis of hopanols derived from a side chain cleavage reaction periodic acid and sodium borohydride of the bacteriohopanepolyols we report quantitative data for bacteriohopanetetrol bht composite tetrafunctionalised biohopanoids pentafunctionalised biohopanoids and hexafunctionalised biohopanoids bht was found in concentrations higher than previously reported up to ca 1500 g g toc but comprised only a relatively small proportion 0 26 of the total biohopanoids in all except one sample composite tetrafunctionalised biohopanoids were the dominant group of bacteriohopanepolyols in all other sediments and are likely to be a major source of the geologically occurring extended hopanes hexafunctionalised biohopanoids were most abundant in lake sediments particularly two small highly productive stratified lakes where they comprised 20 40 of total biohopanoids this feature is interpreted to be due to greater contribution to the organic matter of these sediments from type i methanotrophic bacteria which produce dominantly hexafunctionalised biohopanoids consistent with the environmental settings in the marine environments where sulphate reduction is dominant hexafunctionalised biohopanoids are relatively minor constituents 2 6 of total biohopanoids these data comprise the first clear demonstration that bacteriohopanepolyols vary in composition between depositional environments and have the potential to preserve specific bacterial source information in sedimentary organic matter

biological markers in bitumens and pyrolyzates of upper cretaceous bituminous chalks from the ghareb formation israel abstract the sterane and triterpane distributions of three bituminous chalks from the upper cretaceous ghareb formation israel were investigated both in the original extractable bitumens and in extracts obtained after pyrolysis of whole rock and isolated kerogen samples at 450 c pyrolysis was performed in a closed system under hydrous whole rock and anhydrous conditions isolated kerogens the carbon number distributions of steranes and triterpanes differ significantly between original bitumen and pyrolyzates unlike the bitumens in which diasteranes were not detected the anhydrous pyrolyzates contain small amounts of diasteranes the presence of water during pyrolysis leads to an increase of sterane isomerization the abundant formation of diasteranes and an increase of the 18 h trisnorneohopane 17 h trisnorhopane ratio sterane isomerization maturation parameters show a closer match between original bitumen and pyrolyzates after pyrolysis in a closed system when compared with an open system

crustal magma pathway beneath aso caldera inferred from three dimensional electrical resistivity structure at naka dake cone aso caldera japan volcanic activity is raised cyclically an example of which was a phreatomagmatic eruption in september 2015 using a three dimensional model of electrical resistivity we identify a magma pathway from a series of northward dipping conductive anomalies in the upper crust beneath the caldera our resistivity model was created from magnetotelluric measurements conducted in november december 2015 thus it provides the latest information about magma reservoir geometry beneath the caldera the center of the conductive anomalies shifts from the north of naka dake at depths 10 km toward naka dake along with a decrease in anomaly depths the melt fraction is estimated at 13 15 at 2 km depth moreover these anomalies are spatially correlated with the locations of earthquake clusters which are distributed within resistive blocks on the conductive anomalies in the northwest of naka dake but distributed at the resistive sides of resistivity boundaries in the northeast

hopanoic acids in mesozoic sedimentary rocks their origin and relationship with hopanes abstract hopanoic acids were found in all but the two most mature of a suite of 30 triassic to cretaceous sedimentary rocks their carbon number distributions generally maximise at c 32 consistent with hopanoic acids found in modern sediments the extent of isomerisation measured by and 22s parameters is less for the acids than for associated hopanes possibly due to increased isomerisation of hopanes in association with their generation from macromolecules and functionalised precursors in immature samples the hopane carbon number distributions are consistent with an origin from defunctionalisation of hopanoic acids and other early diagenetically formed hopanoids whilst hopanes in more mature samples exhibit broader carbon number distributions indicative of side chain cleavage during generation of macromolecularly bound hopanoids

shear wave splitting vp vs and gps during a time of enhanced activity at aso caldera kyushu 1 we performed shear wave splitting analyses and calculated vp vs ratios on local earthquakes recorded at seven stations around aso volcano japan between 2001 and 2008 the mean vp vs of 1 61 0 01 from all stations is among the lowest average values found anywhere in the world a temporal change of shear wave splitting fast polarization is observed at one station additionally spatial variations of shear wave splitting delay times and vp vs ratios show a correlation at three stations we suggest that stress controlled anisotropy dominates at these stations gps baselines and 2d strain reveal extension in the caldera in 2003 and compression before and after 2003 strain shortening axes indicate either a variation in regional stress or a local stress source that overprints the regional field in 2003 baseline changes correlate with periods of increased low frequency seismic activity located deeper than 15 km compaction and degassing of a previously reported sill at approximately 15 km depth could lead to constantly high pressure of volcanic gases over a wide area and explain the generally low vp vs ratios and the observed compression in the caldera we propose that a small volume of magma intruded into the sill in 2003 caused extension at the surface and triggered ash eruptions between 2003 and 2005 associated localized migration of gases in overpressured cracks with aspect ratios potentially 0 5 in the upper crust with porosities 0 1 could be the source of changes in seismic anisotropy and explain the slight variations observed in vp vs

extended hopanoids in peat environments abstract detailed results are presented for the distributions of triterpenoid alkanes acids and alcohols of the hopane family in ten samples of peat from three environments and of contributing organisms in the case of lyne of skene scotland extended hopanoids of the and configuration appear at the very earliest stage of diagenesis such environments appear to be characterised by particular distributions of c 32 hopanoid acids and alcohols and a high preponderance of the c 31 hopane

ages of valles marineris mars landslides and implications for canyon history the chronology of landslides of valles marineris the equatorial trough system of mars has been investigated by a crater population study valles marineris landslides have widespread debris aprons which offer a remarkable opportunity to study the crater population with high resolution images from mars orbiter camera moc and from mars odyssey thermal emission imaging system themis sixty six ages were determined within valles marineris including 56 landslide ages and 10 ages of the previous termcanyonnext term floor results reveal that landslides of valles marineris system of previous termcanyonsnext term occurred during a widespread period of time between 3 5 gy and 50 my in some locations the previous termcanyonnext term floor has an apparent age of 3 5 gy suggesting that at least locally within valles marineris no major refreshing processes have occurred for 3 5 gy the temporal repetitivity of landslides implies that the triggering mechanisms of the landslides are reproducible in time landslides have the same features whatever their age the dynamic of these landslides is probably the same either with intervention of water up to recently the last 100 my or without water since 3 5 gy

organic geochemical characteristics and organic matter enrichment of mudstones in an eocene saline lake qianjiang depression hubei province china abstract the qianjiang depression is a typical eocene hypersaline lake basin developing good source rocks in the qianjiang formation which have recently been identified as a potential target for saline lacustrine shale oil exploration previous studies have only focused on estimates of source rock potential and reservoir quality however studies on organic matter enrichment mechanisms in evaporative environments are limited based on organic geochemical and mineralogical data as well as sedimentological analyses we researched the factors controlling differences in organic matter enrichment in the basin the results show that total organic carbon toc contents are closely associated with lithofacies with distinct variations three main lithofacies associations las were identified 1 glauberite rich la1 with medium toc 2 carbonate rich la2 with high toc and 3 anhydrite rich la3 with low toc the distribution of biomarkers from 14 samples indicate both higher land plants and aquatic organisms were involved in the organic matter accumulations combining experimental results on gammacerane c30 hopane extended tricyclic terpane ratio etr sr ba v ni and sedimentary characteristics we analyzed the sedimentary environments of the three las la1 was deposited in a salinity stratified waterbody with strong evaporation la2 was deposited in a still stratified deep waterbody whereas la3 was deposited in a disturbed saline waterbody sedimentary environments not only controlled the formation of the lithofacies but also influenced the organic matter sources and preservation relatively low salinity strong anoxic condition without physical disturbance appropriate nutritional terrigenous material inputs and algal blooms produced the best organic matter enrichment in the saline lake system

mega scale moho relief and the structure of the lithosphere on the eastern flank of the viking graben offshore southwestern norway the international lithosphere project deep reflection seismic survey in the norwegian sector of the north sea has been reprocessed particularly focusing on the deep crust the reflection moho and the upper mantle the data display shifting reflection patterns of the crust and the upper mantle parallel to the eastern margin of the viking graben in the upper crust which is mainly seismically transparent by the processing techniques utilized here large scale structural features like detachment shear zones and master faults can be identified several of the major onshore faults and shear zones match seismic features in the seismic lines many of these structures acted as extensional shear zones in the devonian the middle crust is of variable reflectivity whereas the lower crust is generally strongly reflective and is particularly so in the southern domain the reflection moho is identified throughout the study area but is of variable character the presence of a s e dipping structure hardanger moho offset that displaces the moho by approximately 10 km extends deep into the mantle below the 50 km line depth is positioned where the shallower hardangerfjord shear zone which flattens on the level of the middle crust is situated the hardangerfjord shear zone hardanger moho offset system coincides with change of the crustal thickness depth to moho a change that also coincides with the transition from thin to thick skinned caledonian deformation intramantle reflections are common in the study area some of which are interpreted as shear zones whereas others most likely represent magmatic intrusions

three dimensional seismic velocity structure beneath aso volcano kyushu japan tomographic results for p and s wave velocity structure beneath the active aso volcano kyushu japan using 800 well recorded earthquakes and ten shots recorded by an eight station seismic network are presented a 68 variance reduction was achieved upon simultaneous inversion for hypocenter and velocity structure well resolved velocity anomalies associated with the active crater reveal heterogeneity up to 26 slower and 18 faster in p velocity and up to 31 slower and 22 faster in s velocity than the one dimensional model the largest anomaly is seen over the upper 11 km in the central and northern parts beneath the central cones two low velocity regions are imaged the first region a 10 15 km region encompassing the upper 3 km centered near the caldera wall at tateno valley is characterized by p velocities up to 19 slower 20 for s the second low velocity region is associated with the central cones and active magma conduit system at 6 km depth velocities as low as 4 3 km s up to 26 in p and 2 km s 31 slower in s characterize the 7 km wide volume the magma chamber is roughly spherical in shape centered at 6 km depth flattens at 10 km depth and is located between mt kishima mt eboshi and mt naka the present focus of magmatism a sharp velocity contrast at the depth of 3 km with high velocities to the southwest and lower velocities to the northeast characterizes different abutting structures associated with the oita kumamoto tectonic line

high resolution topomapping of candidate mer landing sites with mars orbiter camera narrow angle images 1 we analyzed narrow angle mars orbiter camera moc na images to produce high resolution digital elevation models dems in order to provide topographic and slope information needed to assess the safety of candidate landing sites for the mars exploration rovers mer and to assess the accuracy of our results by a variety of tests the mapping techniques developed also support geoscientific studies and can be used with all present and planned mars orbiting scanner cameras photogrammetric analysis of moc stereopairs yields dems with 3 pixel typically 10 m horizontal resolution vertical precision consistent with 0 22 pixel matching errors typically a few meters and slope errors of 1 3 these dems are controlled to the mars orbiter laser altimeter mola global data set and consistent with it at the limits of resolution photoclinometry yields dems with single pixel typically 3 m horizontal resolution and submeter vertical precision where the surface albedo is uniform the dominant error is 10 20 relative uncertainty in the amplitude of topography and slopes after calibrating photoclinometry against a stereo dem to account for the influence of atmospheric haze we mapped portions of seven candidate mer sites and the mars pathfinder site safety of the final four sites elysium gusev isidis and meridiani was assessed by mission engineers by simulating landings on our dems of hazard units mapped in the sites with results weighted by the probability of landing on those units summary slope statistics show that most hazard units are smooth with only small areas of etched terrain in gusev crater posing a slope hazard

areally extensive surface bedrock exposures on mars many are clastic rocks not lavas areally extensive exposures of intact olivine pyroxene enriched rock as well as feldspar enriched rock are found in isolated locations throughout the martian highlands the petrogenetic origin s of these rock units are not well understood but some previous studies favored an effusive volcanic origin partly on the basis of distinctive composition and relatively high thermal inertia here we show that the regolith development crater retention and morphological characteristics for many of these bedrock plains are not consistent with competent lavas and reinterpret the high thermal inertia orbital signatures to represent friable materials that are more easily kept free of comminution products through eolian activity candidate origins include pyroclastic rocks impact generated materials or detrital sedimentary rocks olivine pyroxene enrichments in bedrock plains relative to surrounding materials could have potentially formed through deflation and preferential removal of plagioclase

geochemical study on a well in the western canada basin relation of the aromatic distribution pattern to maturity of organic matter abstract thirty one rock samples from a western canada basin well have been analysed for aromatics using glass capillary gas chromatography with simultaneous flame ionization and sulfur selective flame photometric detection a uniform aromatic distribution pattern with a marked predominance of di and tricyclic aromatic hydrocarbons was observed throughout a depth interval of 3000 meters comprising cretaceous and jurassic sediments the very high relative abundance of sulfur aromatics at two narrow intervals in the triassic and mississippian is attributed to a major change in facies gradual changes with increasing depth have been observed for a series of compound ratios which had been calculated from the isomers of methyl and dimethylphenanthrene and their parent compounds these changes reflect the increasing thermal maturation of the sedimentary organic matter a methylphenanthrene index mpi has been introduced which exhibited a very good correlation with vitrinite reflectance data the mpi is the first maturity parameter which is based on a series of aromatic hydrocarbons this hydrocarbon internal maturity parameter permits the recognition and definition of maturity levels in extracts which can be compared to the maturity e g vitrinite reflectance of source rocks

distributions and sources of hopanes hopanoic acids and hopanols in miocene to recent sediments from odp leg 190 nankai trough the distributions and origins of hopanes hopenes hopanoic acids and hopanols in marine sediments from sites 1175 1176 and 1178 ocean drilling program odp leg 190 nankai trough were investigated the high concentrations of hopanoic acids and anhydrobacteriohopanetetrol in the sediments correspond well with a terrestrial contribution as indicated by the abundance of higher plant derived lipids and turbidite layers suggesting that they are mainly transported from land bacteriohopanetetrol and hopanepolyols with short side chains were commonly detected down to about 400 m below sea floor diagenetic transformation from biohopanoids to geohopanoids can take place quickly after the death of bacteria the presence of intact bacteriohopanetetrol in geological sediments tends to suggest an origin from in situ living bacteria so bacteriohopanetetrol might be a potential life marker for deep sub surface bacteria

the interaction between active crustal faults and volcanism a case study of the liquine ofqui fault zone and osorno volcano southern andes using magnetotellurics abstract the relationship between subduction in convergent margins crustal structures and magmatism is crucial to understand processes such as the type and frequency of volcanic activity in these areas although it is well known that the release of fluids by the subducting slab is the main cause of the arc volcanism in areas like the central and southern andes details such as the timing and pathways of magma ascent and storage are still not well understood a key factor that needs to be better studied in the southern volcanic zone of the andes of chile is the role of large tectonic features in fluid transport and magma ascent processes such as the liquine ofqui fault zone a n s strike slip crustal structure parallel to the main volcanic arc in this study we focus on osorno volcano a stratovolcano composed mainly by products of basaltic to basaltic andesite composition with minor dacites and with historical hawaiian strombolian eruptions through the measurement of magnetotellurics and the use of 3 d modeling tools and petrologic constraints two magmatic reservoirs have been inferred which suggest a complex magmatic system with reservoirs of different depths and compositions the shallowest magmatic reservoir 4 8 km has a dacitic composition while the deepest one 7 15 km has an andesitic composition instead the shallow reservoir is located 2 km to the e of the volcano and the deepest one is located 10 km to the e considering that the liquine ofqui fault zone is located 20 km to the e of the volcano we suggest that eruptions of osorno volcano are associated with the ascent of deep crustal basaltic magma enhanced by this master fault re activating the inferred reservoirs and the volcano

diverse biohopanoid compositions of non marine sediments abstract biohopanoid compositions were determined for modern sediments from 27 lacustrine environments and 1 near coastal lagoon gc ms analysis of existing hopanols and those produced by a side chain cleavage reaction periodic acid and sodium borohydride of the bacteriohopanepolyols provided quantitative data for bacteriohopanetetrol bht bacteriohopanepentol and composite tetra penta and hexafunctionalised biohopanoids additional analysis of acetylated total extracts by hplc apci ms has allowed us to identify up to seven intact bacteriohopanepolyols in these environments including the first direct observation of 35 aminobacteriohopanepentol in environmental samples this method is complementary to the periodic acid approach in providing more specific compositional information the lacustrine environments exhibit a wide range of compositions many with high inputs of hexafunctionalised biohopanoids up to 60 of total tetra penta and hexafunctionalised biohopanoids indicative of major contributions to the sediment from type i methanotrophic bacteria several methylated biohopanoids were also detected in most of the samples with 2 as the dominant configuration of the methyl group 2 methylbacteriohopanetetrol was by far the most abundant and most commonly occurring compound of this type and comprised the most abundant bacteriohopanepolyol in one saline lake laguna grande spain such compounds are believed to be derived from cyanobacteria currently the only known quantitatively significant source of 2 methylated biohopanoids biohopanoids containing a methyl group at c 3 were also detected in a limited number of environments these data demonstrate the wide variability in bacteriohopanepolyol compositions among depositional environments and the potential of these compounds to preserve bacterial source information and thereby to record environmental change

kerogen asphaltene sulfur relationships in sulfur rich monterey oils abstract monterey oils in the santa maria basin onshore and offshore are generally low maturity oils because of low thermal exposure relatively shallow burial for short times they are generated as heavy high sulfur oils because of the composition of the unusual type ii source kerogens which are exceptionally rich in organic sulfur 8 14 these high sulfur kerogens which we designate type ii s appear to generate oil at significantly lower thermal exposures than ordinary type ii kerogens with less than 6 s in contrast to common type ii kerogens which generate oil largely by cleavage at oxygen bridge groups and carbon carbon bonds eliminating co2 h2o and hydrocarbon fragments type ii s kerogens have an additional complement of weak bonds associated with bound sulfur the preferential cleavage at weak sulfur linkages tends to produce larger fragments leading to high initial amounts of asphaltenes resins and sulfur rich aromatics together with smaller amounts of saturated hydrocarbons elemental analyses of monterey kerogens and asphaltenes clearly support the concept that the asphaltenes are essentially fragments of kerogen cleaved sufficiently to be soluble or peptized in this heavy oil system solubilization of asphaltenes is attributed to their interactions with the abundant resins and aromatics this sysstem is sufficiently stable under source and reservoir conditions to allow expulsion and migration for reasonable distance without significant fractionation or changes in gross properties initial asphaltenes have essentially the same atomic h c ratios as the source kerogen but have significantlyy lower o c ratios and slightly lower s c ratios the n c ratios are nearly the same for kerogens and their derived asphaltenes with increasing maturity the h c ratios in asphaltenes decrease much like maturation changes in kerogen the s c ratio also decreases significantly however the o c ratios initially low in asphaltenes and n c ratios increase slightly due to material balance caused by other losses these element composition and atomic ratio relationships allow some important inferences concerning source kerogen composition from analysis of asphaltenes alone this can be useful when potential source rock samples are not available for analysis and or when a choice between alternate source rock possibilities must be made

stepped fans and facies equivalent phyllosilicates in coprates catena mars stepped fan deposits and phyllosilicate mineralogies are relatively common features on mars but have not previously been found in association with each other both of these features are widely accepted to be the result of aqueous processes but the assumed role and nature of any water varies in this study we have investigated two stepped fan deposits in coprates catena mars which have a genetic link to light toned material that is rich in fe mg phyllosilicate phases although of different sizes and in separate but adjacent trough like depressions we identify similar features at these stepped fans and phyllosilicates that are indicative of similar formation conditions and processes our observations of the overall geomorphology mineralogy and chronology of these features are consistent with a two stage formation process whereby deposition in the troughs first occurs into shallow standing water or playas forming fluvial or alluvial fans that terminate in delta deposits and interfinger with interpreted lacustrine facies with a later period of deposition under sub aerial conditions forming alluvial fan deposits we suggest that the distinctive stepped appearance of these fans is the result of aeolian erosion and is not a primary depositional feature this combined formation framework for stepped fans and phyllosilicates can also explain other similar features on mars and adds to the growing evidence of fluvial activity in the equatorial region of mars during the hesperian and amazonian

early diagenesis of bacteriohopanoids in recent sediments of lake pollen norway abstract the distribution of free bio and geohopanoids were studied in a short 46 cm core from recent sediments of lake pollen norway bacteriohopanepolyols are abundant components of the sediments totalling up to 321 g g dry sediment 7485 g g toc being dominated by c 32 33 34 35 tetrafunctionalised hopanoids significantly bacteriohopanetetrol only accounts for between 7 to 62 of these 24 on average indicating that composite bacteriohopanoids are more abundant sedimentary constituents and thus more important precursors of geohopanoids than previously recognised downcore profiles of bio and geohopanoid abundance show maxima at ca 25 to 30 cm with a marked decrease in abundance above this depth which coincides with a well documented change in environment from fjord to isolated lake a second maximum in biohopanoid abundance occurs at ca 5 to 12 cm depth specific biohopanoids were affected to different extents by the change in environment suggesting that they have at least partly different sources our data thus indicate that biohopanoids and their geohopanoid products may be sensitive to changes in depositional environment and that they have potential to act as markers for environmental conditions

geochemical study of some cretaceous rocks from kuwait comparison with oils from cretaceous and jurassic reservoirs abstract a set of 18 cretaceous rock samples from wells drilled in the raudhatain and minagish oil fields and 10 oil samples from cretaceous reservoirs raudhatain bahra burgan and minagish oil fields were characterized using geochemical methods including compound specific carbon isotope analyses of n alkanes and isoprenoids in addition one oil miqua from the jurassic marat formation of the great burgan oil field was included in the study despite having high organic carbon content in some samples the burgan and zubair formations and the ratawi shale member of albian to valanginian age are not source rocks for the oils for several reasons but primarily due to lack of correlation of molecular and isotope chemistry as well as a humic organic matter type these results are consistent with the corresponding depositional conditions for these rocks which are deltaic estuarine in the burgan formation and littoral deltaic in the zubair formation the minagish and sulaiy formations of late jurassic to cretaceous age appear to be potential source rock candidates based on their molecular and bulk isotope geochemistry detailed isotopic analysis using individual normal and isoprenoid c 15 alkanes did not provide a good correlation between these possible source rocks and the oils however one sample from the sulaiy formation was found to be comparable to the oils the oils belong to the same genetic family and were expelled from a source rock with a dominant carbonate lithology e g the sulaiy minagish formations these formations contain sulphur rich amorphous kerogen as observed in recent shallow marine shelf deposits the miqua oil which accumulated in the jurassic marat formation reservoir does not differ from the other oils in terms of genetic characteristics this oil is the deepest and most mature of the set maturity assessment has not been possible using well known parameters based on steranes terpanes or methylphenanthrenes however sulphur bearing aromatics comprised of alkylated bt and dbt show important variations parameters based on alkylated bt and dbt have been applied successfully as tools to evaluate maturity changes oil maturity was determined to be middle oil window but has been found not to be related directly to the present depth of the reservoir however it has been established that within the same oil field oil maturity increases with reservoir depth evaluation of these maturity characteristics may be related to major chronological events especially major tectonic movements that have enabled oil to fill different reservoirs successively the reconstruction of the most important phases i e genesis and migration through active faults will provide guidelines to understand the present day maturity pattern of these oils

new aromatic biomarkers in sulfur rich coal abstract a molecular study of linear branched and isoprenyl alkylbenzene skeletons and alkenylbenzenes in the soluble fraction extracted from a sulfur rich utrillas coal was carried out using gas chromatography mass spectrometry gc ms the presence of c24 c28 diaromatic compounds not previously reported in coals suggests that photosynthetic green sulfur bacteria may have made an input of organic matter to these coals the unsaturated linear alkenylbenzenes and isoprenyl c15 and c20 alkylbenzene skeletons are also described for the first time in the soluble fraction of geological samples

amazonian northern mid latitude glaciation on mars a proposed climate scenario recent geological observations in the northern mid latitudes of mars show evidence for past glacial activity during the late amazonian similar to the integrated glacial landsystems in the dry valleys of antarctica the large accumulation of ice many hundreds of meters required to create the observed glacial deposits points to significant atmospheric precipitation snow and ice accumulation and glacial flow in order to understand the climate scenario required for these conditions we used the lmd laboratoire de meteorologie dynamique mars gcm general circulation model which is able to reproduce the present day water cycle and to predict past deposition of ice consistent with geological observations in many cases prior to this analysis however significant mid latitude glaciation had not been simulated by the model run under a range of parameters in this analysis we studied the response of the gcm to a wider range of orbital configurations and water ice reservoirs and show that during periods of moderate obliquity 25 35 and high dust opacity sdust 1 5 2 5 broad scale glaciation in the northern mid latitudes occurs if water ice deposited on the flanks of the tharsis volcanoes at higher obliquity is available for sublimation we find that high dust contents of the atmosphere increase its water vapor holding capacity thereby moving the saturation region to the northern mid latitudes precipitation events are then controlled by topographic forcing of stationary planetary waves and transient weather systems producing surface ice distribution and amounts that are consistent with the geological record ice accumulation rates of 10 mm yr

erosion rate and previous extent of interior layered deposits on mars revealed by obstructed landslides we describe interior layered deposits on mars that have obstructed landslides before undergoing retreat by as much as 2 km these landslides differ from typical martian examples in that their toe height increases by as much as 500 m in a distinctive frontal scarp that mimics the shape of the layered deposits by using crater statistics to constrain the formation ages of the individual landslides to between ca 200 and 400 ma we conclude that the retreat of the interior layered deposits was rapid requiring erosion rates of between 1200 and 2300 nm yr 1 we suggest that the interior layered deposits are either extremely friable if eroded strictly by wind or composed of a material whose degradation has been enhanced by ice sublimation these erosion rates also confirm that the interior layered deposits have been in a state of net degradation over the past 400 m y suggesting that the process that caused net deposition in the past has ceased or slowed substantially on mars relative to erosion our results imply that interior layered deposits with a similar morphology across mars including the mound in gale crater have probably undergone similar rapid erosion and retreat suggesting that their total modern volume underrepresents the depositional record and thus sedimentary history of mars

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

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

preservation and diagenesis of hopanoids in recent lacustrine sediments of priest pot england abstract absolute concentrations of various bio and geohopanoids have been determined in a 24 cm long core from anoxic recent sediments of priest pot a small highly productive lake in the english lake district samples were soxtherm extracted derivatised by methods targeted at specific hopanoid groups and quantified by gc ms periodic acid sodium borohydride treatment was used to cleave the side chains of highly functionalised hopanoids producing products more amenable to our detection methods biohopanoids are extremely abundant totalling up to 3000 g g dry sediment particularly those with composite or highly penta and hexa functionalised side chains suggesting that these are important precursors to sedimentary hopanoids in priest pot downcore biohopanoid abundance profiles show a general diagenetic decline with a marked dip at 5 8 cm which we interpret as a change in bacterial input since this is most marked in the composite hopanoids rather than bacteriohopanetetrol we suggest that these two hopanoid groups have at least partly different sources and may thus have potential as environmental markers the geohopanoids are also abundant totalling up to 1700 g g dry sediment being dominated by the and bishomohopanoic acids and bishomohopanol and hop 17 21 ene downcore plots show no apparent conversion of free bio to geohopanoids with depth which suggests that incorporation into kerogen may be commencing at an early diagenetic stage in the sediments

one million cubic kilometers of fossil ice in valles marineris relicts of a 3 5 gy old glacial landsystem along the martian equator abstract self consistent landform assemblages suggest that valles marineris the giant valley system that stretches along the martian equator was entirely glaciated during late noachian to early hesperian times and still contains huge volumes of fossil ice some of these glacial landform assemblages are illustrated here with representative examples selected in three regions ius chasma central candor chasma and the junction between coprates chasma and capri chasma a morphological boundary separating an upper spur and gully morphology from a smooth basal escarpment has been spectacularly preserved along valley walls throughout valles marineris the boundary winds around topographic obstacles and displays long wavelength variations in elevation it is associated with lateral benches hanging valleys and truncated spurs comparisons with terrestrial analogs indicate that it is most reasonably interpreted as a glacial trimline chasma floors are covered by various kinds of terrains including hummocky terrains platy terrains lateral banks layered benches and a draping mantle landforms in these terrains and their spatial relationship with the interpreted trimline suggest that they correspond to various disintegration stages of an ancient glacial fill currently protected by a superficial cover of ablation till altogether these landforms and terrains compose a full glacial landsystem with wet based glaciers that were able to flow and slide over their beds it was most probably fed by ice accumulating at low elevations directly from the atmosphere onto valley floors and walls with only minor contributions from tributary glaciers flowing down from higher elevations similar fossil glacial landsystems dating back from the early martian history are to be expected in many other low latitude troughs such as chasmata chaos valleys impact craters and other basins

low velocity zones in the crust beneath aso caldera kyushu japan derived from receiver function analyses aso volcano in central kyushu island in southwest japan has a large caldera 18 25 km that formed by the ejection of more than 600 km3 of deposits 89 thousand years ago we calculated receiver functions from teleseismic waveform data obtained from densely distributed stations in and around the caldera we estimated the crustal s wave velocity structure from the receiver functions by using genetic algorithm inversion we detected a low velocity zone vs 2 2 km s at a depth of 8 15 km beneath the eastern flank of the central cones a sill like deformation source has been detected at a depth of 15 5 km by analyses of gps data and a swarm of low frequency earthquakes exists at depths of 15 25 km just beneath this low velocity zone magma may be newly generated and accumulated in this low velocity zone as a result of hot intrusions coming from beneath it except for the region beneath the eastern flank of the central cones a second low velocity zone vs 1 9 km s extends in and around the caldera at a depth of 15 23 km although phenomena representing intrusions have not been detected below it from the estimated velocity structure these low velocity zones are interpreted to contain a maximum of 15 melt or 30 water

ultrahigh resolution topographic mapping of mars with mro hirise stereo images meter scale slopes of candidate phoenix landing sites 1 the objectives of this paper are twofold first to report our estimates of the meter to decameter scale topography and slopes of candidate landing sites for the phoenix mission based on analysis of mars global surveyor mgs mars orbiter camera moc images with a typical pixel scale of 3 m and mars reconnaissance orbiter mro high resolution imaging science experiment hirise images at 0 3 m pixel 1 and second to document in detail the geometric calibration software and procedures on which the photogrammetric analysis of hirise data is based a combination of optical design modeling laboratory observations star images and mars images form the basis for software in the u s geological survey integrated software for imagers and spectrometers isis 3 system that corrects the images for a variety of distortions with single pixel or subpixel accuracy corrected images are analyzed in the commercial photogrammetric software socet set bae systems yielding digital topographic models dtms with a grid spacing of 1 m 3 4 pixels that require minimal interactive editing photoclinometry yields dtms with single pixel grid spacing slopes from moc and hirise are comparable throughout the latitude zone of interest and compare favorably with those where past missions have landed successfully only the mars exploration rover mer b site in meridiani planum is smoother moc results at multiple locations have root mean square rms bidirectional slopes of 0 8 4 5 at baselines of 3 10 m hirise stereopairs one per final candidate site and one in the former site yield 1 8 2 8 slopes at 1 m baseline slopes at 1 m from photoclinometry are also in the range 2 3 after correction for image blur slopes exceeding the 16 phoenix safety limit are extremely rare

evidence for the contemporary magmatic system beneath long valley caldera from local earthquake tomography and receiver function analysis 1 we present a new p wave and s wave velocity model for the upper crust beneath long valley caldera obtained using local earthquake tomography and receiver function analysis we computed the tomographic model using both a graded inversion scheme and a traditional approach we complement the tomographic vp model with a teleseismic receiver function model based on data from broadband seismic stations mlac and mkv located on the se and sw margins of the resurgent dome inside the caldera the inversions resolve 1 a shallow high velocity p wave anomaly associated with the structural uplift of a resurgent dome 2 an elongated wnw striking low velocity anomaly 8 10 reduction in vp at a depth of 6 km 4 km below mean sea level beneath the southern section of the resurgent dome and 3 a broad low velocity volume 5 reduction in vp and as much as 40 reduction in vs in the depth interval 8 14 km 6 12 km below mean sea level beneath the central section of the caldera the two low velocity volumes partially overlap the geodetically inferred inflation sources that drove uplift of the resurgent dome associated with caldera unrest between 1980 and 2000 and they likely reflect the ascent path for magma or magmatic fluids into the upper crust beneath the caldera

maceral composition and molecular markers of two condensed middle holocene peat profiles in n spain abstract this study deals with the palaeohydrological information obtained from lipids composition and vegetal tissue preservation of two peat cores from asturias north spain the two profiles differ in the type of peatland raised bog in la borbolla and blanket bog in buelna and the type of organic matter being more bryophytic in the raised bog and more herbaceous in the blanket bog the peatlands are located close to the coast on impermeable old flat erosion surfaces which favoured peat accumulation within a distance of 3 5 km from each other the accumulation rate varied between 0 05 and 0 07 mm yr and the records extend from around 9000 to 2500 cal yr bp the main differences between the two peat sites can be summarized as follows the raised bog has lower mineral matter content and h c atomic ratio and higher c n ratio and extraction yields compared to the blanket bog it has also a higher tissue preservation index for huminite macerals and increasing inertodetrinite index with depth regarding biomarkers the raised bog has a relatively higher concentration of n alkane 2 ones compared to the corresponding n alkane of similar carbon number higher concentration of medium vs high molecular weight methyl ketones and higher triterpenoids steroids ratio than the blanket bog alternating humid dry periods have been recorded in both profiles based on lipid concentrations indicating that the sphagnum rich intervals in the raised bog are more sensitive than the herbaceous blanket peat record to climatic variations the main humid intervals identified are dated as 5000 7500 cal yr bp in the blanket bog and as 6000 3500 cal yr bp and last 2500 cal yr bp in the raised bog and correlate with the humid periods traced in other peatlands locations in this region the transition middle to late holocene is characterized by humid conditions in the region which favoured the sphagnum growth in the peats the reflectance of huminite in these records appears to be more related with differences in the oxidative conditions than with variation of peat maturity it is higher in the layers with high mineral matter content at the beginning of organic matter accumulation and also in the upper part of the profile subjected to seasonal desiccation a more intense biochemical gelification coincides with higher concentration of hopanoids derived from bacteria in the upper part of the profile acrotelm high amount of nonadecan 2 one k 19 and high concentrations of triterpenyl acetates which are also determined in other peat profiles from northern spain are also detected in these profiles this indicates that the specific conditions required for the formation of these compounds probably associated to wet temperate climate dominated throughout the region

a comparison of rift zone tectonics in iceland and hawaii observations of eroded volcanic rift zones indicate that dikes in iceland are typically several times thicker than those in hawaii geodetic and seismic observations of active rifts however suggest that dike heights in the two regions are similar provided the elastic properties of the rift zones are the same this implies that dikes are intruded with higher driving pressures magma pressure minus compressive stress perpendicular to the dike plane in iceland than hawaii a second major difference between the two regions is the greater prevalence of large normal fault scarps in rift zones in iceland from this it can be infered that a lower percentage of dikes breach the surface in iceland than in hawaii thus although dikes in iceland are intruded with higher driving pressures they possess lower absolute magma pressures than in hawaii these differences can be interpreted in terms of the tectonic settings in the two regions in iceland a steady remote extension reduces the horizontal stress perpendicular to the rift zone allowing dikes to be intruded with low absolute pressures but high driving pressures when magma becomes available in hawaii a more continuous magma supply on the timescale over which the dike induced stresses are relaxed and perhaps a greater role for intrusions in driving long term rift extension ensure that the rift compressive stress is not relaxed significantly before the next dike is intruded thus the magma pressure must be nearly sufficient for eruption in order for intrusion to occur if the mechanism for relaxing the rift compressive stress were less efficient still then an even higher percentage of dikes would erupt and at times the rift zone trend could become an unfavorable orientation for dike intrusion such might be the case at mauna loa which lacks large rift zone faults and fissures and possesses numerous radial vents outside its two main rift zones

molecular and isotopic stratigraphy in an ombrotrophic mire for paleoclimate reconstruction a 40 cm deep sphagnum dominated peat monolith from bolton fell moss in northern england was systematically investigated by lipid molecular stratigraphy and compound specific 13c and d analysis using gas chromatography gc gc mass spectrometry gc ms gc combustion isotope ratio ms gc c irms and gc thermal conversion irms gc tc irms techniques 210pb dating showed the monolith accumulated during the last ca 220 yr a period encompassing the second part of little ice age while the distributions of lipids including n alkan 1 ols n alkan 2 ones wax esters sterols n alkanoic acids alkandioic acids and hydroxy acids display relatively minor changes with depth the cooler climate event was recorded in the concentrations of n alkanes and organic carbon cpi values of n alkanes and n alkanoic acids and the ratio of 5 n alkylresorcinols sterols superimposed on the fossil fuel effect the relatively cooler climate event was also recorded by 13c values of individual hydrocarbons especially the c23n alkane a major compound in certain sphagnum spp the d values of the c29 and c33n alkanes correlated mainly with plant composition and were relatively insensitive to climatic change in contrast the c23n alkane displayed variation that correlated strongly with recorded temperature for the period represented by the monolith agreeing with previously reported deuterium records in tree ring cellulose spanning the same period in scotland germany and the usa with more negative values occurring during the second part of little ice age these biomarker characteristics including the compound specific 13c and d records provide a new set of proxies of climatic change potentially independent of preserved macrofossils which will be of value in deeper sections of the bog where the documentary records of climate are unavailable and humification is well advanced

enhanced erosion rates on mars during amazonian glaciation abstract observations of mars from the surface and from orbit suggest that erosion rates over the last 3 gyr the amazonian have been as slow as 10 5 m myr and have been dominated by aeolian processes while ancient noachian erosion rates may have been orders of magnitude higher due to impact bombardment and fluvial activity amazonian aged glacial deposits are widespread on mars but rates of erosion responsible for contributing debris to these remnant glacial deposits have not been constrained here we calculate erosion rates during amazonian glaciations using a catalog of mid latitude glacial landforms coupled with observational and theoretical constraints on the duration of glaciation these calculations suggest that erosion rates for scarps that contributed debris to glacial landforms are 4 7 orders of magnitude higher than average amazonian rates in non glaciated low slope regions these erosion rates are similar to terrestrial cold based glacier erosion and entrainment rates consistent with cold based glacier modification of parts of mars

novel families of tetra and hexacyclic aromatic hopanoids predominant in carbonate rocks and crude oils two novel families of monoaromatic geomarkers related to hopanoids have been separated and characterized in sediments and crude oils the benzohopanes c32 c35 1 and the ring d aromatized 8 14 secohopanoids c27 c35 4 and 5 both series are particularly abundant in many carbonate samples where they amount to approximately 100 p p m per component in some crude oils but can also be detected in other environments the benzohopanes have been separated as pure compounds by high performance liquid chromatography and identified by x ray diffraction the structure of the 8 14 secohopanoids mostly relies on spectroscopic data nmr and ms and comparison with synthetic analogs both families must be formed in the subsurface from bacterial c35 hopanoid precursors but the benzohopanes seem to occur at an earlier stage of sedimentation the two series appear in varying distributions in the different samples and may therefore be potentially useful as geochemical correlation parameters

geochemical and microfacies characterization of a holocene depositional sequence in northwest germany abstract holocene depositional sequences in the coastal zone of the north sea reflect climate driven sea level changes that led to lateral interfingering of marine brackish lagoonal and limnic sediments and peat layers this succession is reflected in an 18 m sediment core drilled in the marsh lands of the river weser the core spanning the entire holocene was analyzed at high stratigraphic resolution for major and minor elements bulk and molecular constituents and microfacies characteristics abundant triterpenoids in sediments of the basal organic unit indicate nutrient rich limnic paleoconditions not yet influenced by the rising sea level lithological description of several sedimentary units overlying the basal sequence initially suggested a mainly lagoonal setting with occasional influence by tidal channel activities geochemical and microfacies analyses confirmed repeated marine ingression marine conditions are indicated by pyrite enrichment the presence of sterathiols formed by the reaction of sterols with reduced sulfur species and the occurrence of marine pelagic diatoms towards the top of the sedimentary sequence estuarine conditions become more and more pronounced as the river weser established its modern course whereas it had been quite variable previously estuarine conditions are reflected by sterol and amino acid distributions and by limnic diatom species that are mixed with marine pelagic forms although the majority of the clastic units consist of silty to clayey sediments some intercalated quartz sand layers reflect the increase of hydrodynamic energy characteristic of lower tidal flats and channels lumps of reworked peat within fine clastic deposits also reflect high energy events even a dark layer within the upper clastic unit formerly considered a fossil soil horizon is not the direct result of regression induced soil development but originates mainly from eroded fossil organic material from the basal unit this interpretation was established by biomarker analysis and radiocarbon dating

a preparation zone for volcanic explosions beneath naka dake crater aso volcano as inferred from magnetotelluric surveys abstract the 1st crater of naka dake aso volcano is one of the most active craters in japan and known to have a characteristic cycle of activity that consists of the formation of a crater lake drying up of the lake water and finally a strombolian type eruption recent observations indicate an increase in eruptive activity including a decrease in the level of the lake water mud eruptions and red hot glows on the crater wall temporal variations in the geomagnetic field observed around the craters of naka dake also indicate that thermal demagnetization of the subsurface rocks has been occurring in shallow subsurface areas around the 1st crater volcanic explosions act to release the energy transferred from magma or volcanic fluids measurement of the subsurface electrical resistivity is a promising method in investigating the shallow structure of the volcanic edifices where energy from various sources accumulates and in investigating the behaviors of magma and volcanic fluids we carried out audio frequency magnetotelluric surveys around the craters of naka dake in 2004 and 2005 to determine the detailed electrical structure down to a depth of around 1 km the main objective of this study is to identify the specific subsurface structure that acts to store energy as a preparation zone for volcanic eruption two dimensional inversions were applied to four profiles across the craters revealing a strongly conductive zone at several hundred meters depth beneath the 1st crater and surrounding area in contrast we found no such remarkable conductor at shallow depths beneath the 4th crater which has been inactive for 70 years finding instead a relatively resistive body the distribution of the rotational invariant of the magnetotelluric impedance tensor is consistent with the inversion results this unusual shallow structure probably reflects the existence of a supply path of high temperature volcanic gases to the crater bottom we propose that the upper part of the conductor identified beneath the 1st crater is mainly composed of hydrothermally altered zone that acts both as a cap to upwelling fluids supplied from deep level magma and as a floor to infiltrating fluid from the crater lake the relatively resistive body found beneath the 4th crater represents consolidated magma these results suggest that the shallow conductor beneath the active crater is closely related to a component of the mechanism that controls volcanic activity within naka dake

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

stratigraphy and structure of interior layered deposits in west candor chasma mars from high resolution stereo camera hrsc stereo imagery and derived elevations 1 interior layered deposits ilds within western candor chasma were studied by mapping lithologies measuring layer attitudes and comparing the stratigraphy of two adjacent mounds layering tends to dip in the same direction as the local topographic slope although at different angles regionally consistent attitudes do exist suggesting postdepositional block rotations the stratigraphy of two adjacent mounds correlates but the thicknesses of the units differ most layered material appears to have been deposited conformably with one late major unconformity several fault populations are identified and correlate well with regional faults associated with the formation of valles marineris the data suggest that here the ilds predate the faulting and may be early basin fill according to our model for ild formation ilds are deposited syntectonically during early basin collapse subsequent subsidence of surrounding areas accompanied by little or no sedimentation left the early deposits as individual mounds remnants of the former subbasins stratigraphic differences between mounds resulted from different subsidence rates of subbasins a significant change in depositional environment from depositional to a near cessation of deposition and the onset of a major erosion event possibly coincided with the opening of the main valles marineris troughs we further suggest that groundwater played an important role in the formation of sulfates the youngest unit identified not including surficial deposits is likely the result of a posttectonic regionally limited volcanic event if basin collapse continued following the cessation of deposition this model can also account for mounds within closed basins such as hebes