discontinuity surfaces clinoforms and facies architecture in a wave dominated shoreface shelf parasequence abstract detailed outcrop analysis of a wave dominated shoreface shelf parasequence exposed in the book cliffs utah reveals minor stratigraphic discontinuities which define clinoforms two types of discontinuity are recognized each with a distinctive lithologic character and geometry nondepositional discontinuities are marked by an abrupt decrease in the thickness and amalgamation of storm generated event beds and are interpreted to record hiatuses in sedimentation these discontinuities define clinoforms with a concave upward geometry that dip gently 0 02 0 58 over distances of 800 6000 m down depositional dip erosional discontinuities are marked by an abrupt increase in event bed amalgamation grain size and sand content and are interpreted as enhanced storm wave scours these discontinuities define more steeply dipping 0 22 0 95 concave upward clinoforms that extend over 100 1600 m down depositional dip and 500 1500 m along depositional strike the distribution and amalgamation of minor stratigraphic discontinuities defines linear zones of distinctive facies architecture that are oriented parallel to the paleoshoreline trend using the simple assumption that the shoreface shelf equilibrium profile remained approximately constant for each type of discontinuity throughout shoreface migration the bruun rule intra parasequence facies architecture can be speculatively interpreted in terms of shoreline trajectory which reflects the balance between sediment supply and accommodation the resulting interpretations support the notion that shoreline trajectory exerts a strong control on intra parasequence facies architecture and preservation of the shoreface shelf profile

clinoforms and clinoform systems review and dynamic classification scheme for shorelines subaqueous deltas shelf edges and continental margins abstract clinoforms are inclined and normally basinward dipping horizons developed over a range of spatial and temporal scales in both siliciclastic and carbonatic systems the study of clinoform successions underpins sequence stratigraphy and all efforts to reconstruct the relative partitioning of reservoir seal and source rocks along shoreline to basin floor profiles here we review clinoform research and propose a more systematic description and classification of clinoforms this is a crucial step to improve predictions of facies and lithology distribution within shoreline to continental shelf and abyssal plain successions together with the genesis drivers and dynamics of their constituent sedimentary units four basic clinoform types are here distinguished in delta shorelines lacustrine and marine environments on the basis of their overall spatial and temporal scale morphology outbuilding dynamic and geodynamic and depositional setting 1 2 delta scale clinoforms which in turns are sub divided into shoreline and delta scale subaqueous clinoforms 3 shelf edge clinoforms and 4 continental margin clinoforms delta scale clinoform sets are tens of metres high and typically represent 1 103 kyr with progradation rates ranging from 1 000 100 000 m kyr for shorelines and subaerial deltas to 100 20 000 m kyr for subaqueous deltas shelf edge clinoform sets are hundreds of metres high and are nucleated and accreted in 0 1 20 myr usual progradation rates of 1 100 m kyr by successive cross shelf transits of delta scale clinoforms continental margin clinoform sets are thousands of metres high hallmark key geodynamic crustal boundaries e g continent ocean transition and slowly prograde basinwards in ca 5 100 myr with typical rates of 0 1 10 m kyr as a consequence of the very different progradation rates and of the difficulty of large scale clinothems to backstep during transgressions shorelines are the most dynamic clinoforms with regards to position continental margins the least and shelf edges are intermediate shortly after a transgression therefore the four clinoform types may prograde synchronously along shoreline to abyssal plain transects forming compound clinoform systems during the subsequent regressive cycle however due to the dissimilarity in progradation rates different clinoform types will normally merge progressively with each other giving rise to hybrid clinoforms e g shelf edge deltas and fewer depositional breaks in slope are distinguished along a single shoreline to abyssal plain transect overall all clinoform systems are the result of the dynamic evolution of compound and hybrid clinoforms along a temporal and spatial continuum regulated by the cyclical backstepping of the smaller scale system within natural progradational retrogradational cycles of larger scale clinothem outbuilding all clinothem types may show either an accretionary active or draping passive style depending on the proximity to the sediment source draping clinothems are nearly always composed of condensed fine grained sediments while actively accreting clinothems can be composed of predominantly coarse grained i e reservoir forming or predominantly fine grained i e non reservoir lithotypes a novel hierarchical classification scheme for both recent and ancient clinoforms is here proposed consisting of 12 classes the four basic clinoform types delta scale shoreline delta scale subaqueous shelf edge and continental margin are sub divided into eight accretionary active and draping passive sub types 8 division each accretionary sub type is then sub divided into a sandstone prone and mudstone prone variant 12 division which can be at least tentatively predicted on the basis of the clinoform morphology even in the absence of direct stratigraphic logs

chemical element imaging for speleothem geochemistry application to a uranium bearing corallite with aragonite diagenesis to opal eastern siberia russia abstract two complementary image based microanalysis methods digital autoradiography of radioactive elements and x ray fluorescence microspectroscopy micro xrf were used to study the geochemistry of a speleothem from eastern siberia our objective was to show the interest of these micro chemical methods to investigate the distribution of u and some other elements as ca sr and si in speleothems the sample studied was a corallite concretion that formed slowly by the precipitation of minerals from moisture that had condensed underground polished sections of the sample revealed alternating laminas of gray calcite and white aragonite the concretion which is older than 400 kyr u th tims showed no signs of detrital contamination 230 th 232 th 10 000 digital autoradiography and xrf analyses indicated exceptionally high uranium contents ranging from 3 10 to more than 1300 g g 1 in different areas of the sample element maps for calcium ca uranium u strontium sr and silicon si showed inverse correlations between ca and u and between ca and si but there is a strong correlation between si and u under the optical microscope the low ca appears as corrosion voids which were found to contain uranium enriched amorphous silica replacing areas of aragonite and in some cases calcite this postgenetic amorphous and uraniferous silica is composed of two kinds of opal opal a formed by large microspheres of 30 40 m in diameter and a gray opal ct with irregular lepispheres this late opal dated around 385 412 kyr is probably due to a special volcanic event formed by uraniferous glass ashes easily soluble by meteoric waters as suggested by the presence of volcanic suite in the fine fraction of the opal opal precipitated after speleothem crystallization by evaporation or cryogenic supersaturation the study of this exceptional concretion shows the value of direct chemical imaging methods as they easily revealed the presence and distribution of u in the concretion and allowed an unusual case of opal diagenesis in a carbonate speleothem to be described given the value of speleothems as geo chronometers and recorders of environmental changes at different time scales from season to isotopic stage this methodology opens new perspectives in understanding the geochemical system and consequently the validity of radiometric datings u th and u pb especially in speleothem samples

three dimensional modeling of clinoforms in shallow marine reservoirs part 2 impact on fluid flow and hydrocarbon recovery in fluvial dominated deltaic reservoirs permeability contrasts associated with clinoforms have been identified as an important control on fluid flow and hydrocarbon recovery in fluvial dominated deltaic parasequences however they are typically neglected in subsurface reservoir models or considered in isolation in reservoir simulation experiments because clinoforms are difficult to capture using current modeling tools a suite of three dimensional reservoir models constructed with a novel stochastic surface based clinoform modeling algorithm and outcrop analog data upper cretaceous ferron sandstone member utah have been used here to quantify the impact of clinoforms on fluid flow in the context of 1 uncertainties in reservoir characterization such as the presence of channelized fluvial sandbodies and the impact of bed scale heterogeneity on vertical permeability and 2 reservoir engineering decisions including oil production rate the proportion and distribution of barriers to flow along clinoforms exert the greatest influence on hydrocarbon recovery equivalent models that neglect these barriers overpredict recovery by up to 35 continuity of channelized sandbodies that cut across clinoform tops and vertical permeability within distal delta front facies influence sweep within clinothems bounded by barriers sweep efficiency is reduced when producing at higher rates over shorter periods because oil is bypassed at the toe of each clinothem clinoforms are difficult to detect using production data but our results indicate that they significantly influence hydrocarbon recovery and their impact is typically larger than that of other geologic heterogeneities regardless of reservoir engineering decisions clinoforms should therefore be included in models of fluvial dominated deltaic reservoirs to accurately predict hydrocarbon recovery and drainage patterns

trace element variations and dating of a late pleistocene tasmanian speleothem abstract a calcitic stalagmite from lynds cave a limestone cave near mole creek in northern tasmania australia has been dated and shows continuous deposition at a uniform rate from 15 0 to 11 7 ka b p ionium dates or 12 6 8 8 ka b p radiocarbon dates the age difference obtained by comparing the two dating methods is highly significant and strongly supports recent work by bard et al 1990 on barbados corals the speleothem was found to be unsuitable for palaeotemperature estimation by oxygen isotope analysis but the time of deposition is known to have been one rapidly rising temperatures trace element composition was determined by neutron activation analysis naa for fifteen samples spaced along the stalagmite core all elements present in measurable quantities showed significant temporal variation in concentrations which are in part believed to be due to environmental change a significant positive trend in mg sr content and a negative trend in br content appear to be temperature related the halide content is shown to be of terrestrial origin

rock spectral classes observed by the spirit rover s pancam on the gusev crater plains and in the columbia hills 1 this paper examines the ferrous and ferric iron mineralogy of rocks inferred from 246 visible near infrared 430 1010 nm multispectral observations made by the mars exploration rover spirit s pancam on its traverse from its landing site to its second winter haven location principal component correspondence analyses and a sequential maximum angle convex cone technique were used to identify 14 candidate classes spectra from the west spur of husband hill and the watchtower area had the highest 535 and 601 nm band depths indicating that these areas were more oxidized differences in the depth and band center of a near infrared nir absorption feature were observed using 904 nm band depth and 803 904 nm ratio and parameters gauging the 754 864 and 754 1009 nm slopes spectra of rocks from the southern flank of husband hill had negative 754 1009 nm slopes and a broad nir absorption consistent with high olivine abundances rocks observed on the lower west spur at the cumberland ridge locale at the husband hill summit and at the haskin ridge locale had deep 904 nm band depths and steep 754 864 nm slopes consistent with greater pyroxene abundances these observations are consistent with results on iron bearing mineralogy from spirit s mossbauer spectrometer comparisons of these rock spectral classes with a set of terrestrial analog samples found similarities between the west spur and watchtower classes and red hematite bearing impact melts fewer similarities were found in comparisons of the columbia hills classes with basaltic hydrovolcanic tephras

non marine radiaxial fibrous calcites examples of speleothems proved by electron backscatter diffraction abstract the occurrence of radiaxial fibrous calcites rfc in speleothems is documented for the first time using the new electron backscatter diffraction ebsd method up to now in speleothems these precipitates have only been observed as mg containing calcites in close association with aragonite in caves of the temperate to cool central european regions with mean annual temperatures between 4 and 16 c as the four studied occurrences are located in caves in dolomitic and or ankeritic host rocks magnesium is considered to be of particular importance for triggering the formation of radiaxial fibrous mg calcite

the last 40 ka tephrostratigraphic record of lake ohrid albania and macedonia a very distal archive for ash dispersal from italian volcanoes abstract a 1075 cm long core lz1120 was recovered in the south eastern part of the lake ohrid republics of macedonia and albania and sampled for identification of tephra layers magnetic susceptibility investigations show rather high magnetic values throughout the core with peaks unrelated to the occurrence of tephra layers but instead to the relative abundance of detrital magnetic minerals in the sediment naked eye inspection of the core allowed us to identify of two tephra layers at 896 897 cm and 1070 1075 cm laboratory inspection of the grain size fraction 125 m allowed for the identification of a third cryptotephra at 310 315 cm major element analyses on glass shards of the tephra layers at 896 897 cm and 1070 1075 cm show a trachytic composition and indicate a correlation with the regionally dispersed y 3 and y 5 tephra layers dated at ca 30 and 39 cal ka bp the cryptotephra at 310 315 cm has a mugearitic benmoreitic composition and was correlated with the fl eruption of mt etna dated at 3370 70 cal yr bp these ages are in agreement with five 14 c ams measurements carried out on plant remains and macrofossils from the lake sediments at different depths along the core the recognition of distal tephra from italian volcanoes allows us to link the lake ohrid succession to other archives located in the mediterranean area and in eastern europe the benmoreitic mugearitic tephra layer at 310 315 cm is the first recognition in the balkan area of a distal ash deposit from a mid intensity explosive eruption of mt etna as far as 600 km from the source

impact of deltaic clinothems on reservoir performance dynamic studies of reservoir analogs from the ferron sandstone member and panther tongue utah subsurface reservoir models are typically limited by a lack of spatially accurate geometric data on bedform architecture and geometry these factors are key controls on fluid flow outcrop analogs have long been used as a source of such data but the capture of sufficiently precise outcrop data is a challenge the study presented in this article used highly accurate geometrical digital geological outcrop data collected using ground based laser scanning light detection and ranging lidar to build and test three dimensional geocellular models of deltaic reservoir analogs two well exposed ancient river dominated delta systems the panther tongue and the ferron sandstone member which both crop out in central utah were digitally mapped to precisely recreate their clinothem and clinoform geometries in geocellular reservoir modeling software such clinoforms are commonly draped with low permeability mudstones that produce reservoir heterogeneity by subdividing the deltaic sand body into a series of dipping sandstone beds clinothems a key aspect of the modeling was to accurately capture these geometries and their effect on simulated fluid flow portions of the two deltaic systems were dynamically analyzed in a reservoir modeling software by simulating production in 41 models these models tested a range of mudstone barrier continuities and permeabilities results quantify how the continuation of the heterogeneities governed the production rate and recovery factor in the panther tongue models mudstone permeability values were more important in the ferron sandstone models with steeper dipping and closer spaced clinothems although production was still influenced by the continuation of the heterogeneities

remote detection of past habitability at mars analogue hydrothermal alteration terrains using an exomars panoramic camera emulator abstract a major scientific goal of the european space agency s exomars 2018 rover is to identify evidence of life within the martian rock record key to this objective is the remote detection of geological substrates that are indicative of past habitable environments which will rely on visual stereo wide angle and high resolution images and multispectral 440 1000 nm data produced by the panoramic camera pancam instrument we deployed a pancam emulator at four hydrothermal sites in the namafjall volcanic region of iceland a mars analogue hydrothermal alteration terrain at these sites sustained acidic neutral aqueous interaction with basaltic substrates crystalline and sedimentary has produced phyllosilicate ferric oxide and sulfate rich alteration soils and secondary mineral deposits including gypsum veins and zeolite amygdales pancam emulator datasets from these sites were complemented with i nerc airborne research and survey facility aerial hyperspectral images of the study area ii in situ reflectance spectroscopy 400 1000 nm of pancam spectral targets iii laboratory x ray diffraction and iv laboratory vnir 350 2500 nm spectroscopy of target samples to identify their bulk mineralogy and spectral properties the mineral assemblages and palaeoenvironments characterised here are analogous to neutral acidic alteration terrains on mars such as at mawrth vallis and gusev crater combined multispectral and high resolution camera datasets were found to be effective at capturing features of astrobiological importance such as secondary gypsum and zeolite mineral veins and phyllosilicate rich substrates our field observations with the pancam emulator also uncovered stray light problems which are most significant in the nir wavelengths and investigations are being undertaken to ensure that the flight model pancam cameras are not similarly affected

hematite spherules at meridiani results from mi mini tes and pancam 1 we report on observations of hematite bearing spherules at meridiani planum made using the microscopic imager mi mini thermal emission spectrometer mini tes and panoramic camera pancam instruments on the mars exploration rover opportunity spherules were observed on soil surfaces and in outcrop rocks both on undisturbed surfaces and in abraded surfaces ground using the rock abrasion tool rat spherule size and shape change little along the 850 m eastward traverse from eagle crater to endurance crater but spherules decrease and then slightly increase in size along the 6 km traverse from endurance south to victoria crater local populations range from submillimeters to several millimeters in diameter an additional small diameter 100 m size population is possible an increase in irregular shapes is found near victoria crater this combined with the size decrease south of endurance suggests either a changing depositional environment or variation in the duration and timing of diagenetic events the dominant smaller size population observed early in the mission in aeolian areas and ripple crests is observed as the primary size population in abraded outcrop farther south this suggests that successively younger beds are exposed at the surface along the southward traverse stratigraphically higher units removed by erosion could be recorded by the present surface lag deposit coordinated systematic observations are used to determine optical and infrared hematite indices of the surface soils in pancam and mini tes in spite of the systematic variation seen in mi both pancam and mini tes indices are highly variable based on the local surface and neither show systematic trends south of endurance the lack of a 390 cm 1 feature in mini tes spectra suggests concentric or radial interior structure within the spherules at scales too fine for mi to observe mini tes does not detect any silicate component in the spherules a bound water component in soils or in exchange with the atmosphere is observed these spherules have been previously interpreted as concretions formed within what were once water saturated diagenetically altered dirty evaporate sandstone sediments our observations support this interpretation however no single terrestrial analog provides a model that can account for all attributes of the spherules on mars

controls on trace element sr mg compositions of carbonate cave waters implications for speleothem climatic records abstract at two caves clamouse s france and ernesto ne italy cave drip and pool waters were collected and sampled at intervals over a 2 3 year period mg ca and sr ca concentration ratios corrected for marine aerosols are compared with those of bedrocks and in some cases aqueous leachates of soils and weathered bedrocks cave waters do not lie along mixing lines between calcite and dolomite of bedrock carbonate but typically show enhanced and covarying mg ca and sr ca four factors are considered as controlling processes 1 the much faster dissolution rate of calcite than dolomite allows for the possibility of increase of mg ca if water rock contact times are increased during drier conditions a theoretical model is shown to be comparable to experimental leachates 2 prior calcite precipitation along a flow path is a powerful mechanism for generating enhanced and covarying mg ca and sr ca ratios this mechanism requires the solution to lose co 2 into pores or caverns 3 incongruent dolomite dissolution has only limited potential and is best regarded as two separate processes of dolomite dissolution and calcite precipitation 4 selective leaching of mg and sr with respect to ca is shown to be important in leachates from ernesto where it appears to be a phenomenon of calcite dissolution in general selective leaching can occur whenever ca is sequestered into precipitates due to freezing or drying of soils or if there is derivation of excess sr and mg from non carbonate species the ernesto cave has abundant water supply which in the main chamber is derived from a reservoir with year round constant p co 2 of around 10 2 4 and no evidence of calcite precipitation in the karst above the cave two distinct but overlying trends of enhanced and covarying mg ca and sr ca away from the locus of bedrock compositions are due to calcite precipitation within the cave and at a variable drip site due to enhanced selective leaching at slow drip rates mg enhancement in the first chamber is due to a more dolomitic bedrock and longer residence times the clamouse site has a less abundant water supply and presents geochemical evidence of prior calcite precipitation both in the cave and in overlying porous dolomite dedolomitized limestone bedrock initial p co 2 values as high as 10 1 are inferred experimental incubations of clamouse soils which generated enhanced p co 2 and precipitated caco 3 had compositions similar to the karst waters calcite precipitation is inferred to be enhanced in drier conditions hydrological controls on cave water chemistry imply that the trace element chemistry of speleothems may be interpretable in palaeohydrological terms drier conditions tends to promote not only longer mean residence times enhancing dolomite dissolution and hence mg ca but also enhances degassing and calcite precipitation leading to increased mg ca and sr ca

two mathematical models of mg and sr partitioning into solution during incongruent calcite dissolution implications for dripwater and speleothem studies abstract positive correlation between sr ca and mg ca in cave dripwaters and speleothem is often attributed to prior calcite precipitation pcp where exclusion of mg and sr from calcite precipitated upstream of the dripwater speleothem site results in enrichment in the mg ca and sr ca ratios of residual effluent modelling predicts that pcp will produce a straight line correlation in graphs of ln sr ca vs ln mg ca with a theoretical slope that is given by kd sr 1 kd mg 1 calculated to be 0 88 0 13 regardless of rock or absolute dripwater composition sinclair et al submitted for publication while this makes the correlation slope potentially diagnostic for pcp mg and sr are also preferentially released from calcite during incongruent calcite dissolution icd and it is possible that icd produces a similar correlation between ln sr ca and ln mg ca to examine this possibility mathematical formulations for two different mechanisms of icd are presented model 1 simulates net dissolution as a dynamic kinetic process where forward and reverse reactions compete dissolution is congruent but ions are fractionated by a simultaneous reverse reaction where new calcite forms with sr ca and mg ca ratios that are determined by the solution composition and kd sr and kd mg model 2 simulates leaching of mg and sr from a fresh calcite surface by tracking the dissolution of a thin layer where high ion mobility allows the calcite to maintain a homogenous composition controlled by kd sr and kd mg in both models generalised kinetic equations are used in the derivations meaning that the results are not specific to a particular kinetic model in both models of icd the mathematics predict that under conditions that may prevail during dissolution of limestone the correlation between ln sr ca and ln mg ca is approximately linear with a slope given by kd sr 1 kd mg 1 thus this property is not specific to just pcp however for both pcp and icd this slope is universal expected to occur regardless of kinetics and the absolute composition of solution or host rock a correlation slope of 0 88 in either karst waters or speleothem is therefore diagnostic for calcite water interaction

diverse lithologies and alteration events on the rim of noachian aged endeavour crater meridiani planum mars in situ compositional evidence we report the results of geological studies by the opportunity mars rover on the endeavour crater rim four major units occur in the region oldest to youngest the matijevic shoemaker grasberg and burns formations the matijevic formation consisting of fine grained clastic sediments is the only pre endeavour impact unit and might be part of the noachian etched units of meridiani planum the shoemaker formation is a heterogeneous polymict impact breccia its lowermost member incorporates material eroded from the underlying matijevic formation the shoemaker formation is a close analog to the bunte breccia of the ries crater although the average clast sizes are substantially larger in the latter the grasberg formation is a thin fine grained homogeneous sediment unconformably overlying the shoemaker formation and likely formed as an airfall deposit of unknown areal extent the burns formation sandstone overlies the grasberg but compositions of the two units are distinct there is no evidence that the grasberg formation is a fine grained subfacies of the burns formation the rocks along the endeavour crater rim were affected by at least four episodes of alteration in the noachian and early hesperian i vein formation and alteration of preimpact matijevic formation rocks ii low water rock alteration along the disconformity between the matijevic and shoemaker formations iii alteration of the shoemaker formation along fracture zones and iv differential mobilization of fe and mn and caso 4 vein formation in the grasberg and shoemaker formations episodes ii and iii possibly occurred together but i and iv are distinct from either of these

radiaxial fibrous calcites a new look at an old problem abstract marine radiaxial fibrous and fascicular optic calcites are very common but poorly understood pore filling cements in paleozoic and mesozoic marine neritic and upper bathyal limestones the main diagnostic feature of these cements is their converging or diverging crystal c axis respectively the reasons for this anomalous texture are at present unknown another controversy is due to the relative lack of occurrences in cenozoic strata and their apparent absence in quaternary marine limestones despite these uncertainties marine fibrous cements are thought by some to be amongst the best proxies for the geochemistry of ancient oceans because of the absence of metabolic effects during their precipitation applying electron backscatter diffraction analysis we here for the first time document radiaxial fibrous and subordinate fascicular optic fibrous biominerals from well preserved jurassic and cretaceous low mg calcite belemnite rostra the finding of fibrous biogenic calcites in combination with the recent description of holocene and modern fibrous calcites in stalagmites represents in the view of the authors a significant advance in carbonate research here these findings are placed in their wider processes oriented context and the significance of biogenic and speloan fibrous calcite for their marine counterparts is assessed comparing the physico chemical and organomineralic properties of different precipitation sites indicates that the diagnostic variations in the crystal c axis orientation are not related to a specific nucleation environment or substratum in contrast preliminary crystallographic analyses suggest that kinetic factors during nucleation or subtle gradients in the statistical replacements of ca 2 by mg 2 in the crystal structure may lead to local strain resulting in converging or diverging crystal c axes

visible and near infrared multispectral analysis of rocks at meridiani planum mars by the mars exploration rover opportunity multispectral measurements in the visible and near infrared of rocks at meridiani planum by the mars exploration rover opportunity s pancam are described the pancam multispectral data show that the outcrops of the burns formation consist of two main spectral units which in stretched 673 535 432 nm color composites appear buff and purple colored these units are referred to as the hfs and lfs spectral units based on higher and lower values of 482 to 535 nm slope spectral characteristics are consistent with the lfs outcrop consisting of less oxidized and the hfs outcrop consisting of more oxidized iron bearing minerals the lfs surfaces are not as common and appear primarily at the distal ends of outcrop layers and on steep more massive surfaces locations that are subject to greater eolian erosion consequently the hfs surfaces are interpreted as a weathering rind further inherent spectral differences between layers and between different outcrop map units both untouched and patches abraded by the rover s rock abrasion tool are also described comparisons of the spectral parameters of the meridiani outcrop with a set of laboratory reflectance measurements of fe 3 bearing minerals show that the field of outcrop measurements plots near the fields of hematite ferrihydrite poorly crystalline goethite and schwertmannite rind and fracture fill materials observed intermittently at outcrop exposures are intermediate in their spectral character between both the hfs and lfs spectral classes and other less oxidized surface materials basaltic sands spherules and cobbles

soil grain analyses at meridiani planum mars 1 grain size analyses of the soils at meridiani planum have been used to identify rock sources for the grains and provide information about depositional processes under past and current conditions basaltic sand dust millimeter size hematite rich spherules interpreted as concretions spherule fragments coated partially buried spherules basalt fragments sedimentary outcrop fragments and centimeter size cobbles are concentrated on the upper surfaces of the soils as a lag deposit while finer basaltic sands and dust dominate the underlying soils there is a bimodal distribution of soil grain sizes with one population representing grains 125 m and the other falling between 1 4 5 mm soils within craters like eagle and endurance show a much greater diversity of grain morphologies compared to the plains the spherules found in the plains soils are approximately 1 2 mm smaller in size than those seen embedded in the outcrop rocks of eagle and endurance craters the average major axis for all unfractured spherules measured in the soils and outcrop rocks is 2 87 1 18 mm with a trend toward decreasing spherule sizes in both the soils and outcrop rocks as the rover drove southward wind ripples seen across the plains of meridiani are dominated by similar size 1 3 1 7 mm hematite rich grains and they match in size the larger grains on plains ripples at gusev crater larger clasts and centimeter size cobbles that are scattered on the soils have several spectral and compositional types reflecting multiple origins the cobbles tend to concentrate within ripple troughs along the plains and in association with outcrop exposures

ancient impact and aqueous processes at endeavour crater mars the rover opportunity has investigated the rim of endeavour crater a large ancient impact crater on mars basaltic breccias produced by the impact form the rim deposits with stratigraphy similar to that observed at similar sized craters on earth highly localized zinc enrichments in some breccia materials suggest hydrothermal alteration of rim deposits gypsum rich veins cut sedimentary rocks adjacent to the crater rim the gypsum was precipitated from low temperature aqueous fluids flowing upward from the ancient materials of the rim leading temporarily to potentially habitable conditions and providing some of the waters involved in formation of the ubiquitous sulfate rich sandstones of the meridiani region

bromine counts from xrf scanning as an estimate of the marine organic carbon content of sediment cores 1 xrf sediment core scanning technology is increasingly used to quantify sediment composition the overall good correlation between biophilic halogen bromine br and sedimentary total organic carbon toc potentially allows the fast estimation of down core toc profiles by xrf scanning in order to test this approach we present data from the arabian sea and a mediterranean brine basin comparing xrf core scanning br data with discrete sample toc analyses overall br counts and toc show a clear correlation except when stable carbon isotope and c n data indicate intervals characterized by enhanced input of terrestrial organic matter hence solid phase br is exclusively associated with marine organic matter moc and can be used as a direct estimate of this parameter after a calibration is established high pore water br in the brine core steepens the br toc correlation but after salt correction shows a nearly identical gradient to that of the arabian sea core

in flight calibration and performance of the mars exploration rover panoramic camera pancam instruments 1 the mars exploration rover panoramic camera mer pancam instruments have acquired more than 60 000 high resolution multispectral stereoscopic images of soil rocks and sky at the gusev crater and meridiani planum landing sites since january 2004 these images combined with other mer data sets have enabled new discoveries about the composition mineralogy and geologic geochemical evolution of both sites one key to the success of pancam in contributing to the overall success of mer has been the development of a calibration pipeline that can quickly remove instrumental artifacts and generate both absolute radiance and relative reflectance images with high accuracy and precision in order to influence tactical rover driving and in situ sampling decisions this paper describes in detail the methods assumptions and models algorithms in the calibration pipeline developed for pancam images based on new measurements and refinements performed primarily from flight data acquired on mars major calibration steps include modeling and removal of detector bias signal active and readout region dark current electronic shutter smear and pixel to pixel responsivity flatfield variations pancam images are calibrated to radiance w m2 nm sr using refined preflight derived calibration coefficients or radiance factor i f using near in time measurements of the pancam calibration target and a model of aeolian dust deposition on the target as a function of time we are able to verify that the absolute radiance calibration of most pancam images is accurate to within about 10 or less and that the filter to filter and pixel to pixel precision of the calibrated relative reflectance data both based on measurements of the pancam calibration target are typically about 3 and 1 or less respectively examples are also presented of scientific applications made possible by the high fidelity of the calibrated pancam data these include 11 color visible to near ir spectral analysis calculation of true color and chromaticity values and generation of super resolution image data products this work represents a follow on and enhancement to the pancam preflight calibration process described by bell et al 2003

volcanic soil formation in calabria southern italy the cecita lake geosol in the late quaternary geomorphological evolution of the sila uplands abstract this paper focuses on the main morphological physical chemical and mineralogical features of an andic like soil widely outcropping in the sila upland plateau of calabria southern italy and its potential role in tephrostratigraphy a multidisciplinary and multiscale approach allowed identification of this soil as a masked distal archive of volcanic products developed on granite rocks and sediments with a coeval pyroclastic input during pedogenesis the study demonstrates that the contribution of volcanic parent materials can be successfully hypothesized and assessed even in the absence limited extent or poor preservation of primary eruptive products the soil has an andisol like appearance despite laboratory data that do not match the entire suite of diagnostic criteria for the andisol taxonomic order geomorphological stratigraphic and pedologic results coupled with tephrostratigraphic and radiometric data concur to suggest a late pleistocene to holocene age of the andisol like soil in particular the rhyolitic chemical composition of small sized glass fragments identified by sem eds analyses indicates soil genesis contributed by volcanic ash probably sourced from aeolian arc explosive activity spanning the last 30 ka accordingly the evidence of limited relict clay illuviation and the specific type of pedogenesis allowing the development of andic properties in turn related to the neoformation of clay minerals from the weathering of volcanic glass are consistent with a climatic shift from a seasonally contrasted to a constantly humid pedoenvironment this change can be ascribed to the lateglacial or early middle holocene to late holocene transition calibrated ams 14 c dates performed on charcoal fragments sampled from three representative soil profiles provide late holocene ages 3136 19 343 16 and 92 24 yr bp in accord with archaeological finds on the basis of the consistent stratigraphic position lateral continuity and wide extent the soil can be considered a good pedostratigraphic marker in the sila highlands and is informally defined as the cecita lake geosol it supplies valuable time constraints for the underlying occasionally overlying deposits and or soils moreover it allows regional scale morphostratigraphic correlations and detailed reconstruction of late pleistocene holocene geomorphic events in calabria a very suitable region for distal tephra deposition in the central mediterranean peri volcanic area the effects of high energy volcanic eruptions are interfingered with or superimposed by other geomorphic processes and climatic or anthropogenic signals

distribution of discontinuous mudstone beds within wave dominated shallow marine deposits star point sandstone and blackhawk formation eastern utah deposits of wave dominated shorelines are typically considered to act as relatively simple hydrocarbon reservoirs and are commonly modeled as tanks of sand however important heterogeneities that can act as barriers to fluid flow occur at the parasequence bedset and bed scales especially in viscous oil or low permeability oil fields heterogeneities at the parasequence and bedset scales have been well studied but discontinuous mudstone beds occurring within the shoreface have received little attention the book cliffs and wasatch plateau are among the best exposed and best studied deposits of wave dominated shallow marine systems in the world two parasequences within these outcrops have been studied in detail to investigate the distributions of intrashoreface shales and to propose models for the controls on their distribution a data set consisting of 30 km 18 6 mi of virtual outcrops derived from oblique helicopter mounted light detection and ranging lidar scanning with supporting stratigraphic sections makes it possible to collect a large quantity of accurate geometric data of depositional elements from inaccessible cliffs nine hundred and twenty one discontinuous mudstone beds were measured these occur as ellipses with long axes oriented normal to the paleoshoreline lengths and widths of these mudstone beds exhibit a lognormal distribution with means of 21 9 and 13 8 m 71 9 and 45 3 ft respectively within the shoreface succession the number of mudstone beds increases downward whereas size does not vary significantly with stratigraphic height an average of 100 m 328 ft cumulative length of shale exists per 100 m 328 ft of horizontal outcrop this increases threefold near both wave dominated deltas and bedset boundaries that reflect minor sea level fluctuations during progradation

tephrostratigraphy and tephrochronology in the philippi peat basin macedonia northern hellas greece abstract three tephra layers have been identified in the upper 15 m of a 190 m section of peat beneath the philippi fen they provide significant lithological and chronological markers throughout the fen and the aegean region the upper tephra pht1 consists of shards of a transparent calcalkaline felsic glass and fragments of plagioclase augite hypersthene and rare hornblende magnetite apatite and quartz peat directly beneath pht1 gave a radiocarbon approximate age of 13 000 yr the middle tephra layer pht2 which resembles pht1 in chemistry and petrography but contains more crystals and lithic fragments rests on peat dated ca 18 000 14 c yr bp the lower tephra pht3 has colorless to brown glass shards with a trachytic chemistry and a mineral assemblage of sanidine sodic plagioclase biotite aegirine augite hornblende titanite and apatite bracketing radiocarbon ages imply that pht3 accumulated about 30 000 14 c yr bp the likely ages of pht1 and pht2 together with their mineralogical and chemical characteristics suggest that these tephras came from the volcanic field of thera in the hellenic arc pht2 particularly was derived from a major known explosive eruption ca 18 000 yr bp the cape riva eruption correlative to the y 2 tephra layer evidence for pht3 suggests derivation from the campanian province of italy and correlation with the campanian ignimbrite and the y 5 ash beneath the mediterranean sea

controls on trace element partitioning in cave analogue calcite abstract we report trace element data from a series of carbonate growth experiments in cave analogue conditions in the laboratory with the goal of better understanding environmental controls on trace element incorporation in stalagmites the experimental setup closely mimics natural processes e g precipitation driven by co2 degassing low ionic strength solution thin solution film but with a tight control on growth conditions temperature pco2 drip rate calcite saturation index and the composition of the initial solution calcite is dissolved in deionized water in a 20 000 ppmv pco2 environment with trace elements li na mg co sr cd ba u at appropriate concentrations to mimic natural cave drip waters this solution is dripped onto glass plates coated with seed calcite in a lower pco2 environment at 7 15 25 and 35 c and drip rates of 2 6 and 10 drips per minute d sr was shown to be statistically invariant over the full range of temperature and growth rate studied no relationship between sr ca and growth rate is therefore expected in stalagmite samples over comparable growth rates d mg has a relationship with temperature defined by d mg 0 01e0 02 0 006 t but temperature is not expected to be the dominant control on mg ca in cave calcite due to the larger impact of calcite precipitation on mg ca over short timescales in conditions where temperature is well buffered the fraction of calcium remaining in solution f is likely to be the dominant control on mg ca and other trace element ratios but differences in the response of trace elements to f and t may allow their combined use to assess past cave conditions high cd castalagmite is particularly indicative of low amounts of prior calcite precipitation and cd ca would be a useful addition to trace element studies of natural stalagmites significant scatter is observed in trace element ratios during the laboratory experiments which cannot be explained by simple rayleigh distillation this scatter is well explained by solution mixing and by the mixing of calcite with different fractions of calcite growth accounting for the effects of mixing on trace element concentrations or ratios may help to achieve more robust interpretations of stalagmite chemistry as part of a multi proxy approach to assessment of past environments

constraining uncertainty in interpretation of seismically imaged clinoforms in deltaic reservoirs troll field norwegian north sea insights from forward seismic models of outcrop analogs forward seismic modeling of outcrop analogs has been used to characterize the seismic expression of clinoforms in different deltaic depositional environments and thus constrain uncertainty in interpretation of intra reservoir clinoforms imaged in seismic data from the troll field norwegian north sea three outcrop analogs from the cretaceous western interior seaway united states were studied to quantify the geometry distribution and lithologic character of clinoforms in fluvial dominated and mixed influence deltaic deposits outcrop derived geometric data were calibrated to sedimentological and petrophysical data from the krossfjord and fensfjord formations in the troll field and then used to create a suite of forward seismic models for comparison with real seismic reflection data from the troll field clinoforms were imaged in the forward seismic models in which they were 1 spaced wider than the tuning thickness 10 m 33 ft 2 marked by pronounced interfingering of facies associations with different acoustic properties and or 3 lined by relatively thick 50 cm 20 in carbonate cemented layers however where clinothems are thinner than the vertical resolution limit of seismic data destructive interference occurred creating misleading geometrical relationships furthermore our ability to image clinoforms is dependent on 1 the frequency of the seismic wavelet 2 the overburden velocity and or 3 the acoustic impedance contrast at the boundary between the overburden and the clinoform bearing target the established methodology has allowed characterization of deltaic clinoformal architectures in reservoir seismic data from the troll field and has facilitated a more robust interpretation by bridging the critical gap in resolution between well and seismic data

observations of rock spectral classes by the opportunity rover s pancam on northern cape york and on matijevic hill endeavour crater mars the opportunity rover s exploration of the portion of the rim of endeavour crater known as cape york included examination of the sulfate bearing grasberg formation and the matijevic hill region multispectral visible and near infrared vnir pancam observations were used to characterize reflectance properties of rock units using spectral end member detection and classification approaches including a principal components n dimensional visualization automatic sequential maximum angle convex cone method and classification through hierarchical clustering six main spectral classes of rock surfaces were identified light toned veins grasberg fm the smectite bearing matijevic formation the hematitic blueberry spherules resistant spherules within the matijevic fm dubbed newberries and the shoemaker formation impact breccia some of these could be divided into spectral subclasses there were three types of veins veins in the bench unit of cape york thinner veins in the matijevic fm and boxwork pattern forming veins the bench unit veins had higher 535 nm band depths than the other two vein subclasses and a steeper 934 to 1009 nm slope the grasberg fm has vnir spectral features that are interpreted to indicate higher fractions of red hematite than in the sulfate bearing burns fm the matijevic fm includes both light toned fine grained matrix and dark toned veneers the latter has a weak near infrared absorption band centered near 950 nm consistent with nontronite observations of rock abrasion tool brushed and ground newberries indicated that cuttings from the rat grind had a longer wavelength reflectance maximum and deeper 535 nm band depth consistent with more oxidized materials greater oxidation of cementing materials in the newberries is consistent with a diagenetic concretion origin

stable isotope data as constraints on models for the origin of coralloid and massive speleothems the interplay of substrate water supply degassing and evaporation abstract many speleothems can be assigned to one of two morphological groups massive speleothems which consist of compact bulks of material and coralloids which are domal to digitate in form faster growth on protrusions of the substrate occurs in the typical growth layers of coralloids where those layers are termed coralloid accretions but it is not observed in the typical layers of massive speleothems which in contrast tend to smoothen the speleothem surface and can therefore be defined as smoothing accretions the different growth rates on different areas of the substrate are explainable by various mechanisms of caco3 deposition e g differential aerosol deposition differential co2 and or h2o loss from a capillary film of solution deposition in subaqueous environments to identify the causes of formation of coralloids rather than massive speleothems this article provides data about 13c and 18o at coeval points of both smoothing and coralloid accretions examining the relationship between isotopic composition and the substrate morphology in subaerial speleothems data show enrichment in heavy isotopes both along the direction of water flow and toward the protrusions the first effect is due to h2o evaporation and co2 degassing during a gravity driven flow of water gravity stage and is observed in smoothing accretions the second effect is due to evaporation and degassing during water movement by capillary action from recesses to prominences capillary stage and is observed in subaerial coralloids both effects coexist in smoothing accretions interspersed among coralloid ones intermediate stage thus this study supports the origin of subaerial coralloids from dominantly capillary water and disproves their origin by deposition of aerosol from the cave air on the other hand subaqueous coralloids seem to form by a differential mass transfer from a still bulk of water toward different zones of the substrate along diffusion flux vectors of nutrients perpendicular to the iso depleted surfaces finally this isotopic method has proved useful to investigate the controls on speleothem morphology and to obtain additional insights on the evolution of aqueous solutions inside caves

the geometry and internal architecture of stream mouth bars in the panther tongue and the ferron sandstone members utah u s a abstract clinothems are seaward dipping beds which are deposited during the progradation of delta front mouth bars measurements taken from clinothems in the field and from geospatially constrained photo realistic virtual outcrops were used to record clinothem dip maximum bed thickness and bed thickness every 10 m along a series of depositional dip oriented profiles from two ancient river dominated delta successions which crop out in central utah usa these data show systematic changes in bed dip and bed thinning which highlight discrete packaging of the beds into bedsets interpreted to represent the progradation of stream mouth bars in the delta front individual bedsets are characterized by a progressive steepening of beds coupled with a more rapid thinning systematic collection of 2800 locations along 73 separate clinothems from the panther tongue sandstone member and parasequence 1f from the ferron sandstone were used to study the relationship between bed thickness dip and decay gradient parameter which describes the down dip bed thinning clinothems in the panther tongue are much longer and more gently dipping than the clinothems in the ferron sandstone in both systems beds can be clustered into groups bedsets which show a systematic decrease in values and an increase in dip angle boundaries between the groups are defined by a sudden increase in values and a concurrent decrease in dip angle these bedsets are interpreted to represent individual stream mouth bars which amalgamate to form mouth bar complexes within the delta front sand bodies the use of virtual outcrops was essential for the collection of the large volumes of thickness data and the recognition of very subtle 1 changes in dip angle which have made these interpretations possible

tephrostratigraphy study for the last 18 000 14 c years in a deep sea sediment sequence for the south adriatic abstract a detailed tephrostratigraphy supported by accelerator mass spectrometry ams 14c dating and isotopic and geochemical analyses has been carried out for a deep sea core collected from the southern adriatic sea which spans the last 18 14c kyr fourteen ash layers have been recognized in the marine core and the origin was determined by comparing their age and geochemistry with tephra detected in terrestrial deposits the geochemical signatures of marine ash layers indicate a prevailing campanian and subordinate etnean and eolian provenances collectively they are attributed to sources in the phlegraean fields lam lagno amendolare ln1 ln2 gm1 c 2 nyt neapolitan yellow tuff c 1 agnano pomici principali ams pf agnano monte spina ast astroni somma vesuvius l9 pomici di base l8 greenish mount etna et1 y1 biancavilla ignimbrite lipari e 1 gabellotto fiumebianco and palinuro seamount pal 1 some of these eruptions have been detected for the first time in marine cores astroni lam l9 l8 and three were detected and dated by marine tephra ln1 ln2 and pal 1 providing new more precise stratigraphic markers for the last 18 kyr in the south adriatic marine record

phyllosilicates and sulfates at endeavour crater meridiani planum mars 1 phyllosilicates have been identified on the martian surface from orbit and are hypothesized to have formed under wet non acidic conditions early in the planet s history exposures of these minerals have not yet been examined by a landed mission using mars reconnaissance orbiter data we report the detection of phyllosilicate bearing outcrops that may be accessible by the mars exploration rover opportunity currently exploring meridiani planum the phyllosilicates are associated with layered polygonally fractured rocks exposed in the rim of the 20 km diameter crater endeavour these rocks may have formed via regional or global scale processes of aqueous alteration that predated the period of acid sulfate formation recorded in the rocks that opportunity has studied to date detailed characterization by opportunity could better constrain the conditions under which these phyllosilicates formed hydrated sulfates are also detected from orbit in the plains adjacent to endeavour s rim providing the first opportunity for ground truth of these detections

ancient aqueous environments at endeavour crater mars opportunity has investigated in detail rocks on the rim of the noachian age endeavour crater where orbital spectral reflectance signatures indicate the presence of fe 3 rich smectites the signatures are associated with fine grained layered rocks containing spherules of diagenetic or impact origin the layered rocks are overlain by breccias and both units are cut by calcium sulfate veins precipitated from fluids that circulated after the endeavour impact compositional data for fractures in the layered rocks suggest formation of al rich smectites by aqueous leaching evidence is thus preserved for water rock interactions before and after the impact with aqueous environments of slightly acidic to circum neutral ph that would have been more favorable for prebiotic chemistry and microorganisms than those recorded by younger sulfate rich rocks at meridiani planum

vnir multispectral observations of rocks at cape york endeavour crater mars by the opportunity rover s pancam from its arrival at the portion of the rim of endeavour crater known informally as cape york the mars exploration rover opportunity has made numerous visible and near infrared vnir multispectral observations of rock surfaces this paper describes multispectral observations from opportunity s arrival at cape york to its winter over location at greeley haven averages of pixels from the pancam s left and right eyes were joined to form 11 point spectra from numerous observations and were examined via a number of techniques these included principal components analysis a sequential maximum angle convex cone approach examination of spectral parameters and a hierarchical clustering approach the end result of these analyses was the determination of six primary spectral ps classes describing spectrally unique materials observed on cape york these classes consisted of a standard outcrop spectrum that was observed on the clasts and matrix comprising the upper unit of the shoemaker formation a class representing rock surfaces exposed around odyssey crater and typified by the rocks of the tisdale series pebbles occurring in and weathered out of the upper unit of the shoemaker formation that appear red in 1009 904 754 nm color composites patches on tisdale rocks exhibiting a 864 nm band minimum that were spectrally anomalous in root mean square error images derived from spectral mixture analyses clasts with a high 904 nm band depth occurring in the greeley haven location and gypsum veins typified by the vein homestake comparisons of three of these classes that had well defined band minima between 800 and 1009 nm with spectral library spectra of ferrous silicates and ferric oxide oxyhydroxide and ferric sulfate minerals indicated tentative matches of the red pebbles with orthopyroxenes of the spectrally anomalous 864 nm band minimum material with hematite or ferric sulfates and of the high 904 nm band depth material with an orthopyroxene clinopyroxene mixture the spectral properties of rock surfaces on cape york are distinct from those of burns formation outcrops observed on the meridiani plains the cape york outcrop is noachian in age and study of these materials provides insight into less acidic environmental conditions extant before the formation of the burns formation

surface albedo observations at gusev crater and meridiani planum mars 1 during the mars exploration rover mission the pancam instrument has periodically acquired large scale panoramic images with its broadband 739 338 nm filter in order to estimate the lambert bolometric albedo of the surface along each rover s traverse in this work we present the full suite of such estimated albedo values measured to date by the spirit and opportunity rovers along their traverses in gusev crater and meridiani planum respectively we include estimated bolometric albedo values of individual surface features e g outcrops dusty plains aeolian bed forms wheel tracks light toned soils and crater walls as well as overall surface averages of the 43 total panoramic albedo data sets acquired to date we also present comparisons to estimated lambert albedo values taken from the mars global surveyor mars orbiter camera moc along the rovers traverses and to the large scale bolometric albedos of the sites from the viking orbiter infrared thermal mapper irtm and mars global surveyor thermal emission spectrometer tes the ranges of pancam derived albedos at gusev crater 0 14 to 0 25 and in meridiani planum 0 10 to 0 18 are in good agreement with irtm tes and moc orbital measurements these data sets will be a useful tool and benchmark for future investigations of albedo variations with time including measurements from orbital instruments like the context camera and high resolution imaging science experiment on mars reconnaissance orbiter long term accurate albedo measurements could also be important for future efforts in climate modeling as well as for studies of active surface processes

basic building blocks and process variability of a cretaceous delta internal facies architecture reveals a more dynamic interaction of river wave and tidal processes than is indicated by external shape abstract although delta building processes and the resultant facies and facies associations have been studied for over a century there remains a lack of well documented facies architectural studies of ancient deltas in this study architectural element analysis is applied to determine the basic building blocks of a cretaceous delta at the top of the upper turonian wall creek member exposed along the western flanks of the powder river basin wyoming we document the bed scale basic building blocks of this ancient delta and show them in the context of their facies and stratal variability and their hierarchical spatial arrangement within a single deltaic parasequence we also test the idea that external sand body shape may not reflect the internal facies complexity as has recently been suggested in studies of several modern deltas including the burdekin in australia the brazos in the gulf of mexico and the baram trusan in borneo five orders of bounding surfaces separate six facies architectural elements in the prodelta and delta front deposits these elements are prodelta fines pf frontal splay fs channel ch storm sheet ss tidally modulated deposit tm and bar accretion ba seasonal to decadal river floods are thought to represent the main building phases of the delta producing channels bars and frontal splay elements during intervening periods the delta was reworked by waves storms and tides producing tidally modulated and storm sheet elements due to the complex interactions of river effluents with waves storms and tides the delta is interpreted as mixed influenced regional sandstone isolith facies and paleocurrent maps help to reconstruct the paleogeography and show how the various architectural elements varied across the delta front the channels bars frontal splays and tidally modulated elements are found only near the distributary mouth whereas the storm sheets occur extensively away from the distributary mouth the plan view morphology of the studied delta shows a smooth fronted arcuate to cuspate shape which should indicate wave dominance in contrast our analysis of the internal facies architecture shows that the delta was constructed rapidly during major river floods with significant tidal reworking additional outcrop mapping shows that storm wave reworked sands are attached to the flanks of the system previously published delta models predict incorrectly that the tidal reworking of a river flood dominated system should result in a more bird foot shape versus the lobate geometry that is actually mapped our analysis of internal facies versus external shape matches similar observations on several modern deltas and suggests that external shape is a poor indicator of internal facies complexity

correlation techniques perforation strategies and recovery factors an integrated 3 d reservoir modeling study sirikit field thailand production in the sirikit oil field of the phitsanulok basin thailand commenced in 1982 the field has an stoiip stock tank oil initially in place of approximately 800 mmbbl million barrels to date more than 130 wells have been drilled and over 100 mmbbl produced reservoir management studies into optimizing recovery and identifying unswept oil volumes are ongoing so as to maximize the venture s profitability this work includes 3 d three dimensional static and dynamic modeling this study is one such exercise whereby different geological correlation techniques and perforation strategies were analyzed for their potential impact on recovery factors the sirikit field and adjacent satellite fields are composed of predominantly lacustrine mouth bar and fluvial deposits two correlation techniques lithostratigraphy and chronostratigraphy were employed to generate two 3 d reservoir architectures using the shell proprietary 3 d static reservoir modeling system geocap significantly different recovery factors are derived from 3 d dynamic flow simulation of these architectures no vertical upscaling 2 x 2 areal upscaling within the shell proprietary reservoir simulator mores when good quality sands observed on well logs are perforated in both models the lithostratigraphic correlation model results in an absolute 3 higher recovery factor than that of the chronostratigraphic correlation model in relative terms this represents a 43 higher recovery factor this suggests that if a lithostratigraphic correlation model is assumed then for this perforation strategy the recovery factor would be overestimated by 3 absolute and 43 relative if the chronostratigraphic interpretation represents the actual subsurface architecture in addition the architecture of the chronostratigraphic model results in the lateral correlation of the thicker upper mouth bar sands with good quality thin bedded toeset sands and shales heterolithics these thin bedded sands are only marginally resolvable on wireline logs and have not generally been perforated in the sirikit field when these thin bedded heterolithics are additionally perforated in the 3 d model an absolute increase in recovery factor of 2 is observed over the same model that has only the upper mouth bar sands perforated in relative terms this represents a 28 improvement in the recovery factor this work confirms and partially quantifies the impact that the choice of mouth bar correlation style can have on recovery factors as predicted by 3 d dynamic reservoir models however the chronostratigraphic model described in this paper represents an end member connectivity scenario whereby sand body continuity is relatively low due to continuous dipping shale barriers further work is required to quantify the recovery factors for the whole spectrum of potential chronostratigraphic model connectivity scenarios

quantitative outcrop data for flow simulation abstract an architectural analysis documents variations in bedding geometry and rock properties within a tide influenced deltaic sandstone exposed in the cretaceous frontier formation of central wyoming usa digital maps of bedding lithofacies and diagenetic cements as well as vertical logs of grain size lithofacies and permeability describe rock properties that potentially influence fluid flow behavior these records are used to construct simulation models that assess the relative importance of different types of geologic variability on prediction of subsurface fluid flow two 25 meter thick tide influenced deltaic sandstone bodies coarsen upward and contain inclined beds that reflect episodic delta front progradation decimeters to meters thick beds within bodies alternate between cross stratified sandstones formed during rapid flows and shales deposited during more quiescent conditions down depositional dip bed draping shales are more continuous and lithofacies within sandstone beds become finer grained and increasingly heterolithic as sandstone beds fine down dip mean permeability values decrease and coefficients of variation increase permeability values change from nearly normal distributions to highly right skewed and permeability values become more strongly spatially correlated nodular cements also affect permeability all of these variations were modeled using stratigraphic cornerpoint grids that preserve stratal geometry and gridblocks with properties assigned using a combination of rock property maps and statistical models based on rock property logs simulations predict effects on fluid flow of geologic heterogeneity at different scales the influences of process variables and the effects of different methods of grid construction and rock property assignment flow simulations of water flooding through a 22 m thick by 360 m long segment of a deltaic sandstone oil reservoir predict that 1 rapid flow through coarser grained deposits at the top of the sandstone body tends to draw water upward 2 thin shales draping sandstone beds shunt downdip directed flow downward and updip directed flow upward 3 cement nodules cause more tortuous flow patterns but have little effect on recovery efficiency 4 methods of predicting intrafacies correlation of permeability have little effect on flow behavior at this scale a simulation model constructed using a high resolution cartesian grid did not resolve the effects of inclined shales demonstrating the usefulness of stratigraphic cornerpoint grids for modeling flow through complex geologic deposits flow simulations of tracer flow through a meter thick cross stratified bed within the deltaic sandstone body showed that at this scale shale drapes and models of the intrafacies distribution of permeability have statistically significant effects

autostratigraphy a framework norm for genetic stratigraphy abstract autostratigraphy is the stratigraphy generated by large scale autogenic processes and needs to be heeded because of a current overreliance on allogenic controls in sequence stratigraphy key principles of autostratigraphy emerging from the theory of autoretreat and a new understanding of alluvial grade derive from the non equilibrium stratigraphic response i e the general lack of equilibrium configuration of depositional systems the non equilibrium behavior of fluvial deltas during times t of steady dynamic forcing leads to variable stratigraphic response that is the inevitable result of length d and time scaling particular to the depositional system rather than necessarily reflecting any sudden or unsteady change in the rate of allogenic forcing some abrupt breaks in the stratigraphic record are not necessarily associated with changes in allogenic conditions but can result from purely autogenic processes of the system when t is comparable to or longer than 1 the depositional system takes the non equilibrium large scale autogenic response 2 the superposition of autogenic and allogenic components of the forcing is prominently nonlinear and thus 3 sequence stratigraphic models that have been built on the assumption of equilibrium response are incorrect autostratigraphic analysis makes it possible to detect and identify complex autogenic responses and unsteady allogenic events in the stratigraphic record by quantifying a temporal change in the magnitude of d autostratigraphy thus functions as a norm for genetic stratigraphy

esperance multiple episodes of aqueous alteration involving fracture fills and coatings at matijevic hill mars in the search for evidence of past aqueous activity by the mars exploration rover opportunity fracture filling veins and rock coatings are prime candidates for exploration at one location within a segment of remaining rim material surrounding endeavour crater a set of boxwork fractures in an outcrop called esperance are filled by a bright hydrated and highly siliceous sio2 66 wt material which has overall a montmorillonite like chemical composition this material is partially covered by patches of a thin dark coating that is sulfate rich so3 21 wt but also contains significant levels of si fe ca and mg the simultaneous presence of abundant s si and fe indicates significant mineralogical complexity within the coating this combination of vein and coating compositions is unlike previous analyses on mars both materials are heterogeneously eroded presumably by eolian abrasion the evidence indicates at least two separate episodes of solute precipitation from aqueous fluids at this location possibly widely separated in time in addition to the implications for multiple episodes of alteration at the surface of the planet aqueous chemical environments such as these would have been habitable at the time of their formation and are also favorable for preservation of organic material

speleothem trace element signatures a hydrologic geochemical study of modern cave dripwaters and farmed calcite trace element variations in ancient cave speleothems are often interpreted as indicators of changes in paleo rainfall and hydrologic conditions however these records are difficult to interpret without an understanding of the physicochemical controls on stalagmite chemistry plus site specific calibration of changes in net rainfall to variations in dripwater and speleothem chemistry in this study we examine geochemical relationships between net rainfall precipitation minus evapotranspiration p et drip rates drip water chemistry and contemporaneous calcite chemistry to test the hypothesis that speleothem mg ca and sr ca records are proxies for rainfall amount hrc is contained within four low magnesium limestone units capped sporadically by a remnant dolomitic limestone aqueous concentrations of magnesium post evapotranspiration decrease with increasing vertical travel distance between the soil zone and the point of in cave drip emergence drip path length dpl as dissolved high mg solutions sourced from the dolomitic caprock are diluted with dissolved low mg limestone waters sourced from the host limestone dripwater mg ca and sr ca ratios covary and provide diagnostic indicators of the two dominant mechanisms controlling dripwater chemistry 1 mixing of post evaporative solutions derived from two geochemical endmembers dissolution of dolomite and limestone and 2 evolution of hydrochemistry away from dissolved bedrock compositions due to prior calcite precipitation pcp above the drip sites by resolving the linear mixing relationships for drip water mg ca and sr ca sources and the distribution coefficients for trace element transfer in the pcp dripwater to calcite precipitation reactions and applying these principles to our time series we find that the extent of pcp production within the karst is directly controlled by the balance between precipitation p and evapotranspiration et higher net rainfall p et 1 wet conditions reduces pcp and lower net rainfall with increased evapotranspiration p et 1 increases pcp farmed calcite x ca ratios faithfully track hydrologically influenced seasonal variations in dripwater chemistry for x mg sr and na however the relationship between changes in net rainfall and changes in mg ca and sr ca ratios in modern calcite is unique at each site and differs significantly at closely spaced drip stalagmite locations this suggests that in situ modern hydrochemical calibrations should be performed atop individual speleothems prior to harvesting for paleoclimate investigations and that such calibrations may not reflect past conditions as drip paths change we apply this understanding to published dripwater data and speleothem time series from other caves a major implication is that in order to interpret stalagmite sr ca and mg ca ratios as wet vs dry proxies speleothem sr ca and mg ca variations must be coherent and in phase over all time periods i e sr mg ratios must be constant these criteria will help to distinguish rainfall amount versus rainfall source in speleothem 18o records

characterization of stratigraphic architecture and its impact on fluid flow in a fluvial dominated deltaic reservoir analog upper cretaceous ferron sandstone member utah fluviodeltaic stratigraphic architecture and its impact on fluid flow have been characterized using a high resolution three dimensional reservoir scale model of an outcrop analog from the upper cretaceous ferron sandstone member of central utah the model contains two parasequence sets delta complexes each with five or six parasequences separated by an interval of coastal plain strata each parasequence contains one or two laterally offset teardrop shaped delta lobes that are 6 to 12 km 4 7 mi long 3 to 9 km 2 6 mi wide 5 to 29 m 16 95 ft thick and have aspect ratios width length of 0 4 to 0 8 delta lobes have a wide range of azimuthal orientations 120 around an overall east northeastward progradation direction in plan view delta lobes in successive parasequences exhibit large as much as 91 clockwise and counterclockwise rotations in progradation direction which are attributed to autogenic lobe switching in cross sectional view parasequence stacking is strongly progradational but a small component of aggradation or downstepping between parasequences reflects relative sea level fluctuations we use flow simulations to characterize the impact of this heterogeneity on production in terms of the sweep efficiency which is controlled by 1 the continuity orientation and permeability of channel fill sand bodies 2 the vertical permeability of distal delta front heteroliths 3 the direction of sweep relative to the orientation of channel fill and delta lobe sand bodies and 4 well spacing distributary channel fill sand bodies terminate at the apex of genetically related delta lobes and provide limited sand body connectivity in contrast fluvial channel fill sand bodies cut into and connect multiple delta lobe sand bodies low but non zero vertical permeability within distal delta front heteroliths also provides connectivity between successive delta lobe sand bodies

dynamic changes and processes in the mississippi river delta research in the modern delta of the mississippi river has revealed short term changes and processes that are of significant magnitude deltaic lobes each lobe covering an area of 30 000 sq km and having an average thickness of 35 km switch sites of deposition on an average of every 1 500 yr through short periods of geologic time this process results in a relatively thick accumulation of stacked deltaic cycles covering extremely large areas within a single delta lobe and operating on an even higher frequency are bay fills and overbank splays bay fills having areas of 250 sq km and thickness of 15 m require only 150 yr to accumulate four major events have taken place in the modern balize delta since 1838 overbank splays are much smaller covering areas of less than 2 sq km and having thicknesses of 3 m but are associated with high floods on the river at the river mouth continued progradation of the distributary channel can form distributary mouth sand bodies that have dimensions of 17 km long 8 km wide and a thickness of 80 m in a period of only 200 yr differential sedimentary loading at the river mouth results in formation of diapirs that display vertical movements in excess of 100 m in a period of 20 yr on the subaqueous delta platform sediment instabilities operate nearly continuously mass moving large quantities of shallow water deposits to deeper water environments via arcuate rotational slides and mudflow gullies and depositional lobes all of these changes and processes operate at differing spatial and temporal scales but all result in deposition of large volumes of sediment over extremely short periods of time

silica rich deposits and hydrated minerals at gusev crater mars vis nir spectral characterization and regional mapping abstract the mars exploration rover mer spirit has discovered surprisingly high concentrations of amorphous silica in soil and nodular outcrops in the inner basin of the columbia hills in pancam multispectral observations we find that an absorption feature at the longest pancam wavelength 1009 nm appears to be characteristic of these silica rich materials however spectral analyses of amorphous silica suggest that the 1009 nm spectral feature is not a direct reflection of their silica rich nature based on comparisons with spectral databases we hypothesize that the presence of h 2 o or oh either free as water ice adsorbed or bound in a mineral structure is responsible for the spectral feature observed by pancam the gertrude weise soil which is nearly pure opaline silica may have adsorbed water cold trapped on mineral grains the origin of the 1009 nm pancam feature observed in the silica rich nodular outcrops may result from the presence of additional hydrated minerals specific sulfates halides chlorides sodium silicates carbonates or borates using the 1009 nm feature with other spectral parameters as a hydration signature we have mapped the occurrence of hydrated materials along the extent of spirit s traverse across the columbia hills from west spur to home plate sols 155 1696 we have also mapped this hydration signature across large panoramic images to understand the regional distribution of materials that are spectrally similar to the silica rich soil and nodular outcrops our results suggest that hydrated materials are common in the columbia hills

vnir multispectral observations of aqueous alteration materials by the pancams on the spirit and opportunity mars exploration rovers multispectral visible and near infrared vnir observations from the mars exploration rover pancam multispectral stereo camera systems are consistent with materials having been subjected to various aqueous processes ferric oxides in the form of hematite in the burns and grasberg formations of meridiani planum have been well characterized by opportunity on the basis of strong 535 and 864 nm absorptions and positive 754 1009 nm and 934 1009 nm slopes on the rim of noachian aged endeavour crater opportunity has observed light toned veins with high ca and s as determined by the rover s alpha particle x ray spectrometer apxs and a negative 934 1009 nm slope in vnir spectra extracted from pancam data indicative of a 1000 nm h2o overtone absorption together these observations indicate that the veins are composed of gypsum rocks overturned by opportunity on the murray ridge portion of the endeavour crater rim display dark and light toned coatings the dark toned coatings have a red featureless slope that is consistent with the slope observed in laboratory spectra of high valence manganese oxide minerals potential mn oxide coatings may also be associated with some exposures of the grasberg formation apxs results for high mg and s in the light toned coatings of the murray ridge overturned rocks and a negative 934 1009 nm slope are consistent with hydrated mg sulfates opportunity has also observed spectral features in rocks that are consistent with orbital observations of fe smectites as well as al smectites and possible hydrated silica in light toned fracture fill materials the spirit rover observed sulfate rich light toned soils exposed by the rover s wheels several of these soil observations contained spectral features such as a broad absorption centered near 800 nm consistent with ferric sulfate minerals a finding confirmed by the rover s mossbauer spectrometer spirit also excavated light toned si rich soils these soils have a flat near infrared spectrum with a drop in reflectance from 934 1009 nm that is consistent with free water contained in voids or adsorbed onto the surface of the silica

geology and stratigraphy of fluvio deltaic deposits in the ivishak formation applications for development of prudhoe bay field alaska significant remaining reserves in prudhoe bay field are confined within deltaic rocks at the base of the triassic ivishak sandstone the initial stratigraphic characterization of the prudhoe bay reservoir was lithostratigraphically based and it depicted this basal reservoir interval as tabular zones between marine shale and overlying coarse grained fluvial sandstones a reassessment of this interval based on cores and genetic stratigraphic correlations depicts en echelon offlapping fluvially dominated deltaic wedges reservoir quality rocks occur in distributary mouth bar distributary channel and fluvial facies associations a paleogeographic reconstruction of one delta lobe includes an alluvial plain crossed by channels of possibly braided or low sinuosity rivers this alluvial plain graded into a delta plain cut by distributary channels that fed distributary mouth bars on a broad delta front river dominance is inferred from the abundance of unidirectional current structures normally graded beds soft sediment deformation and general absence of wave formed tidal and biogenic structures slumping and growth faulting locally replaced coarsening upward deltaic successions with sharp based overthickened mouth bar and distributary channel deposits mudstones deposited following delta lobe abandonment form laterally extensive flow barriers between lobes compartmentalization is most pronounced distally where deltaic sandstones are overlain by and pass laterally into marine shale proximally fluvial and deltaic sandstones are juxtaposed across erosional contacts improving reservoir continuity this stratigraphic interpretation is corroborated by production and surveillance data plus an interference test locally stratigraphy and poor waterflood performance reflect completions in diachronous sandstones that originated in separate deltaic lobes previously poor well performances were attributed to sandstone pinch outs in some cases production can be enhanced with recompletions rather than infill drilling nonconventional wells planned and completed with the benefit of detailed facies association correlations currently are recovering millions of barrels of previously bypassed oil

mars exploration rover athena panoramic camera pancam investigation 1 the panoramic camera pancam investigation is part of the athena science payload launched to mars in 2003 on nasa s twin mars exploration rover mer missions the scientific goals of the pancam investigation are to assess the high resolution morphology topography and geologic context of each mer landing site to obtain color images to constrain the mineralogic photometric and physical properties of surface materials and to determine dust and aerosol opacity and physical properties from direct imaging of the sun and sky pancam also provides mission support measurements for the rovers including sun finding for rover navigation hazard identification and digital terrain modeling to help guide long term rover traverse decisions high resolution imaging to help guide the selection of in situ sampling targets and acquisition of education and public outreach products the pancam optical mechanical and electronics design were optimized to achieve these science and mission support goals pancam is a multispectral stereoscopic panoramic imaging system consisting of two digital cameras mounted on a mast 1 5 m above the martian surface the mast allows pancam to image the full 360 in azimuth and 90 in elevation each pancam camera utilizes a 1024 1024 active imaging area frame transfer ccd detector array the pancam optics have an effective focal length of 43 mm and a focal ratio of f 20 yielding an instantaneous field of view of 0 27 mrad pixel and a field of view of 16 16 each rover s two pancam eyes are separated by 30 cm and have a 1 toe in to provide adequate stereo parallax each eye also includes a small eight position filter wheel to allow surface mineralogic studies multispectral sky imaging and direct sun imaging in the 400 1100 nm wavelength region pancam was designed and calibrated to operate within specifications on mars at temperatures from 55 to 5 c an onboard calibration target and fiducial marks provide the capability to validate the radiometric and geometric calibration on mars

uranium series chronology and environmental applications of speleothems an increasing number of scientists recognize the value of speleothems1 as often extremely well preserved archives of information about past climate vegetation hydrology sea level nuclide migration water rock interaction landscape evolution tectonics and human action well constrained data are required to document past changes reconstruct past patterns and predict future responses of the earth system at a wide range of spatial and temporal scales speleothems are particularly useful in this regard because they can be found in many locations of the globe sampled at high resolution and reliably dated using high precision uranium series techniques speleothems are bodies of mineral material formed in caves as the result of chemical precipitation from groundwater flowing or dripping in a cave most speleothems are composed of calcite formed by slow degassing of co2 from supersaturated groundwater but aragonite and gypsum forms are also common particularly near cave entrances where evaporative effects are important a host of different speleothem types decorate the walls ceilings and floors of caves and their mineralogy and morphology is a function of fluid flow and chemistry of waters feeding a particular location as well as the ambient conditions temperature chemistry light in the air or water filled void subaerial forms include the familiar stalagmites stalactites draperies flowstones subaqueous forms include rimstone pools rafts mammillary calcite wall coatings and dog tooth spar for an extensive review of the types of speleothem that have been observed see hill and forti 1997 speleothems are used in a multitude of ways to explore past environmental conditions perhaps the most fundamental of which is their very presence or absence deposition of speleothems relies on sufficient water supply and soil co2 to enable dissolution and transport of reactants in the vadose zone to underlying caves in arid or glacial times conditions may not have been favorable for speleothem formation

spectral variability among rocks in visible and near infrared multispectral pancam data collected at gusev crater examinations using spectral mixture analysis and related techniques 1 visible and near infrared vnir multispectral observations of rocks made by the mars exploration rover spirit s panoramic camera pancam have been analyzed using a spectral mixture analysis sma methodology scenes have been examined from the gusev crater plains into the columbia hills most scenes on the plains and in the columbia hills could be modeled as three end member mixtures of a bright material rock and shade scenes of rocks disturbed by the rover s rock abrasion tool rat required additional end members in the columbia hills there were a number of scenes in which additional rock end members were required the sma methodology identified relatively dust free areas on undisturbed rock surfaces as well as spectrally unique areas on rat abraded rocks spectral parameters from these areas were examined and six spectral classes were identified these classes are named after a type rock or area and are adirondack lower west spur clovis wishstone peace and watchtower these classes are discriminable based primarily on near infrared nir spectral parameters clovis and watchtower class rocks appear more oxidized than wishstone class rocks and adirondack basalts based on their having higher 535 nm band depths comparison of the spectral parameters of these gusev crater rocks to parameters of glass dominated basaltic tuffs indicates correspondence between measurements of clovis and watchtower classes but divergence for the wishstone class rocks which appear to have a higher fraction of crystalline ferrous iron bearing phases despite a high sulfur content the rock peace has nir properties resembling plains basalts

dripwater organic matter and trace element geochemistry in a semi arid karst environment implications for speleothem paleoclimatology a series of four short term infiltration experiments which revealed hydrochemical responses relevant to semi arid karst environments were carried out above cathedral cave wellington new south wales nsw australia dripwater samples were collected at two sites for trace element and organic matter analysis organic matter was characterised using fluorescence and interpreted using a parafac model three components were isolated that represented unprocessed soil derived humic like and fulvic like material processed humic fulvic like material and tryptophan like fluorescence principal component analysis pca performed on the entire dataset comprising trace element concentrations and parafac scores revealed two dominant components that were identified as soil and limestone bedrock the soil component was assigned based on significant contributions from the parafac scores and additionally included ba cu ni and mg the bedrock component included the expected elements of ca mg and sr as well as si the same elemental behaviour was observed in recent stalagmite growth collected from the site our experiments demonstrate that existing paleoclimate interpretations of speleothem mg and sr developed in regions of positive water balance are not readily applicable to water limited environments we provide a new interpretation of trace element signatures unique to speleothems from water limited karst environments

petrology and geochemistry of annually laminated stalagmites from an alpine cave obir austria seasonal cave physiology calcite stalagmites from obir an alpine 1100 m altitude perennially wet cave were studied using optical and electron backscatter diffraction petrology bulk icp ms analysis and microanalysis by ion microprobe and micro x ray fluorescence using synchrotron radiation drip water penetrates 70 m through triassic limestones with some pb zn mineralization to the chamber saulenhalle where the stalagmites were collected and with which we compared drip water compositions however the cave is also characterized by strong seasonal ventilation leading to low pco2 in winter all samples display autumnal event lamination defined by a narrow optically visible zone with trace element enrichments within which synchrotron studies have resolved micron scale enrichments of pb and zn crystallite scale 10 m lateral trace element variations reflect alternate smooth faces and rough crystal edges induced by high zn content seasonal falls in sulphate s and increase in 13c can be associated with the winter ventilation the elemental covariations support the transport of pb zn p f br and i by organic colloids but final depositions from aerosols rather than dripwater should be considered the chemical variations are powerful expressions of seasonal cave physiology but the study points to important gaps in our understanding of colloidal element transport in ventilated caves

mineralogic and compositional properties of martian soil and dust results from mars pathfinder mars pathfinder obtained multispectral elemental magnetic and physical measurements of soil and dust at the sagan memorial station during the course of its 83 sol mission we describe initial results from these measurements concentrating on multispectral and elemental data and use these data along with previous viking snc meteorite and telescopic results to help constrain the origin and evolution of martian soil and dust we find that soils and dust can be divided into at least eight distinct spectral units based on parameterization of imager for mars pathfinder imp 400 to 1000 nm multispectral images the most distinctive spectral parameters for soils and dust are the reflectivity in the red the red blue reflectivity ratio the near ir spectral slope and the strength of the 800 to 1000 nm absorption feature most of the pathfinder spectra are consistent with the presence of poorly crystalline or nanophase ferric oxide s sometimes mixed with small but varying degrees of well crystalline ferric and ferrous phases darker soil units appear to be coarser grained compacted and or mixed with a larger amount of dark ferrous materials relative to bright soils nanophase goethite akaganeite schwertmannite and maghemite are leading candidates for the origin of the absorption centered near 900 nm in imp spectra the ferrous component in the soil cannot be well constrained based on imp data alpha proton x ray spectrometer apxs measurements of six soil units show little variability within the landing site and show remarkable overall similarity to the average viking derived soil elemental composition differences exist between viking and pathfinder soils however including significantly higher s and cl abundances and lower si abundances in viking soils and the lack of a correlation between ti and fe in pathfinder soils no significant linear correlations were observed between imp spectral properties and apxs elemental chemistry attempts at constraining the mineralogy of soils and dust using normative calculations involving mixtures of smectites and silicate and oxide minerals did not yield physically acceptable solutions we attempted to use the pathfinder results to constrain a number of putative soil and dust formation scenarios including palagonitization and acid fog weathering while the pathfinder soils cannot be chemically linked to the pathfinder rocks by palagonitization this study and mcsween et al 1999 suggest that palagonitic alteration of a martian basaltic rock plus mixture with a minor component of locally derived andesitic rock fragments could be consistent with the observed soil apxs and imp properties

high resolution synchrotron x ray fluorescence investigation of calcite coralloid speleothems elemental incorporation and their potential as environmental archives synchrotron high resolution and micro x ray fluorescence elemental mapping of two coeval coralloid speleothems from lamalunga cave italy are complemented with petrographic morphological and microstratigraphic studies the importance of these speleothems relies on their direct and indirect association with a complete neanderthal skeleton altamura man found inside the cave the coralloids grew discontinuously between 64 6 ka and the holocene and reveal exceptionally high concentrations of mg sr and si particularly on convex surfaces where evaporation is more intense the incorporation of trace elements depends on several factors including location shape and geometrical evolution during their growth as well as climate and environmental parameters this resulted in calcite precipitation with sr compositions from 100 to 1200 ppm and an average concentration of 7000 ppm mg an unusually high si content up to 16 is possibly derived from volcanic ash transported as particulate and in solution inside the cave the most common fabrics observed consist of non fluorescent elongated columnar calcite forming clean isopachous bands and fluorescent fibre like crystals associated with laminated lenticular bands high in sr mg and si variability in sr mg and si concentrations appears to induce fabric changes in the coralloids elongation and lattice distortion of the crystals was found to coincide with high mg concentrations the transition from compact elongated to open to fibre like is here interpreted as due to high concentrations of si and sr which are preferentially incorporated in the speleothem at crystal boundaries and intra laminae it is here inferred that coralloid fabric changes and their elemental content potentially record local rainfall variations through time with the clean compact calcite marking high infiltration and open fibre like and micrite fabrics recording dry periods

speleothems as sensitive recorders of volcanic eruptions the bronze age minoan eruption recorded in a stalagmite from turkey mounting evidence exists that variations in sulphur content in stalagmites are closely linked to changes in volcanic or anthropogenic atmospheric sulphur the strong dependency of sulphur on soil ph and ecosystem storage however can result in a delay of several years to decades in the registration of volcanic eruptions and anthropogenic emissions by stalagmites here we present synchrotron radiation based trace element analysis performed on a precisely dated section of a stalagmite from sofular cave in northern turkey as this section covers the time interval of the intensively studied minoan volcanic eruption between 1600 and 1650 bc we can test whether this vigorous eruption can be traced in a stalagmite of all measured trace elements only bromine shows a clear short lived peak at 1621 251621 25 bc whereas sulphur and molybdenum show peaks later at 1617 251617 25 and 1589 251589 25 respectively we suggest that all trace element peaks are related to the minoan eruption whereas the observed phasing of bromine molybdenum and sulphur is related to differences in their retention rates in the soil above sofular cave for the first time we can show that bromine appears to be an ideal volcanic tracer in stalagmites as it is a prominent volatile component in volcanic eruptions can be easily leached in soils and rapidly transferred from the atmosphere through the soil and bedrock into the cave and stalagmite respectively highly resolved oxygen and carbon isotope profiles indicate that the minoan eruption had no detectable climatic and environmental impact in northern turkey