liquefaction evidence for strong earthquakes of holocene and latest pleistocene ages in the states of indiana and illinois usa abstract sand and gravel filled clastic dikes of seismic liquefaction origin occur throughout much of southern indiana and illinois nearly all of these dikes originated from prehistoric earthquakes centered in the study area in this area at least seven and probably eight strong prehistoric earthquakes have been documented as occurring during the holocene and at least one during the latest pleistocene the recognition of different earthquakes has been based mainly on timing of liquefaction in combination with the regional pattern of liquefaction effects but some have been recognized only by geotechnical testing at sites of liquefaction most paleo earthquakes presently recognized lie in indiana but equally as many may have occurred in illinois studies in illinois have not yet narrowly bracketed the age of clastic dikes at many sites which sometimes causes uncertainty in defining the causative earthquake but even in illinois the largest paleo earthquakes probably have been identified prehistoric magnitudes were probably as high as about moment magnitude m 7 5 this greatly exceeds the largest historic earthquake of m 5 5 centered in indiana or illinois the strongest paleo earthquakes struck in the vicinity of the concentration of strongest historic seismicity elsewhere paleo earthquakes on the order of m 6 7 have occurred even where there has been little or no historic seismicity both geologic and geotechnical methods of analysis have been essential for verification of seismic origin for the dikes and for back calculating prehistoric magnitudes methods developed largely as part of this study should be of great value in unraveling the paleoseismic record elsewhere

petrofacies of eocene sand injectites of the tumey giant injection complex california usa abstract the forearc succession of great valley group in central california provides some of the best examples of giant sand injection complexes in the world and is therefore considered valuable analogues for injectite systems in the subsurface several sand injection complexes are well described in the outcrop and subsurface however the petrographic characteristics of injectites are still poorly documented in this paper we present the results of an integrated study of field observations quantitative and qualitative sandstone petrography provenance and petrofacies analysis of the tumey giant injection complex tgic in order to understand its lithostratigraphy and petrological evolution and its impacts on reservoir petrofacies characteristics and fluid migration the tgic intrudes into a 450 m thick deep water succession of slope mudrocks and sandy channel fills of the kreyenhagen shale eocene forming an interconnected network of sandstone sills dykes and injection breccias the complex generated a horizontal and vertical plumbing system for fluid migration connecting isolated sandy channel fills among low permeability mudrocks the primary detrital composition diagenetic products microtextures and provenance signatures allowed for the definition and discrimination of depositional and intrusive petrofacies and their genetic relations petrofacies associations confirm that the gypsum cemented feldspathic litharenites from the kreyenhagen shale channel fills are the only source for the injection complex eodiagenetic compaction and extensive gypsum cementation reduced the primary porosity of the complex while telodiagenetic dissolution of autigenic constituents formed pervasive secondary porosity the underlying calcite cemented arkosic sandstones of the lodo and domengine formations acted as barriers for fluid flow aiding lateral fluid migration and overpressure buildup within the overlying kreyenhagen channel fills intense grain microfracturing occurred during sand remobilization and injection along with erosion of the host mudrocks this study has significance for the generation of reliable stratigraphic and petrological models for sand injection complex genesis and evolution that consequently can help the understanding and exploration of injectite complexes elsewhere

shock effects in quartz compression versus shear deformation an example from the rochechouart impact structure france abstract different quartz microstructures from rochechouart impact breccias indicative of shock induced compression and shear deformation are compiled to obtain information on the mean stress and the deviatoric components of the shock wave associated stress annealed rhombohedral planar deformation features pdfs are widespread in quartz from rochechouart impact breccias as analysed by optical microscopy scanning electron and transmission electron microscopy shocked quartz can show mosaicism with domains of quartz microstructures in the rochechouart impact breccias that record shock induced shear deformation are mechanical brazil twins and planar fractures that are supposed to represent microfaults these shock effects indicate high differential stress on the order of a few gpa quartz that contains brazil twins and planar fractures shows no or few rhombohedral pdfs indicating relatively low shock pressures 20 gpa are apparently not accompanied by high differential stresses only at attenuated shock pressure

discovery of jarosite within the mawrth vallis region of mars implications for the geologic history of the region abstract analysis of visible to near infrared reflectance data from the mro crism hyperspectral imager has revealed the presence of an ovoid shaped landform approximately 3 by 5 km in size within the layered terrains surrounding the mawrth vallis outflow channel this feature has spectral absorption features consistent with the presence of the ferric sulfate mineral jarosite specifically a k bearing jarosite kfe3 so4 2 oh 6 terrestrial jarosite is formed through the oxidation of iron sulfides in acidic environments or from basaltic precursor minerals with the addition of sulfur previously identified phyllosilicates in the mawrth vallis layered terrains include a basal sequence of layers containing fe mg smectites and an upper set of layers of hydrated silica and aluminous phyllosilicates in terms of its fine scale morphology revealed by mro hirise imagery the jarosite bearing unit has fracture patterns very similar to that observed in fe mg smectite bearing layers but unlike that observed in the al bearing phyllosilicate unit the ovoid shaped landform is situated in an east west bowl shaped depression superposed on a north sloping surface spectra of the ovoid shaped jarosite bearing landform also display an anomalously high 600 nm shoulder which may be consistent with the presence of goethite and a 1 92 m absorption which could indicate the presence of ferrihydrite goethite jarosite and ferrihydrite can be co precipitated and or form through transformation of schwertmannite both processes generally occurring under low ph conditions ph 2 4 to date this location appears to be unique in the mawrth vallis region and could represent precipitation of jarosite in acidic sulfur rich ponded water during the waning stages of drying

iron mobility during diagenesis at vera rubin ridge gale crater mars the curiosity rover investigated a topographic structure known as vera rubin ridge associated with a hematite signature in orbital spectra there curiosity encountered mudstones interpreted as lacustrine deposits conformably overlying the 300 m thick underlying sedimentary rocks of the murray formation at the base of mount sharp while the presence of hematite fe o was confirmed in situ by both mastcam and chemcam spectral observations and by the chemin instrument neither chemcam nor apxs observed any significant increase in feo t total iron oxide abundances compared to the rest of the murray formation instead curiosity discovered dark toned diagenetic features displaying anomalously high feo t abundances commonly observed in association with light toned ca sulfate veins but also as crystal pseudomorphs in the host rock these iron rich diagenetic features are predominantly observed in grey outcrops on the upper part of the ridge which lack the telltale ferric signature of other vera rubin ridge outcrops their composition is consistent with anhydrous fe oxide as the enrichment in iron is not associated with enrichment in any other elements nor with detections of volatiles the lack of ferric absorption features in the chemcam reflectance spectra and the hexagonal crystalline structure associated with dark toned crystals points toward coarse grey hematite in addition the host rock adjacent to these features appears bleached and show low feo t content as well as depletion in mn indicating mobilization of these redox sensitive elements during diagenesis thus groundwater fluid circulations could account for the remobilization of iron and recrystallization as crystalline hematite during diagenesis on vera rubin ridge

an application of heavy mineral analysis to lithostratigraphy and reservoir modelling in the oseberg field northern north sea abstract three distinctive detrital garnet associations have been recognized in brent group sandstones of the oseberg area northern north sea by means of electron microprobe analysis these have lithostratigraphical significance with one association occurring in the etive and oseberg formations one in the ness formation and one in the tarbert formation the stratigraphic variation in garnet population reflects changes in provenance and in the pattern of distribution of clastic detritus although a detailed reconstruction of source areas is not possible on the basis of the available information differentiation of ness and etive oseberg formations by means of detrital garnet geochemistry has enabled the recognition of fluvial chanbel sandstones belonging to the ness formation which have cut down into the etive formation shoreline complex this provides direct evidence of communication between ness and etive oseberg adding an extra degree of sophistication to the geological input for reservoir simulation a strong permeability anisotropy can be modelled around the fluvial channels and a net sand volume can be modelled in agreement with channel orientation

the chemcam remote micro imager at gale crater review of the first year of operations on mars abstract the mars science laboratory rover curiosity landed near the base of a 5 km high mound of layered material in gale crater mounted on the rover mast the chemcam instrument is designed to remotely determine the composition of soils and rocks located a few meters from the rover using a laser induced breakdown spectrometer libs coupled to a remote micro imager rmi we provide an overview of the diverse imaging investigations that were carried out by chemcam s rmi during the first year of operation on mars 1182 individual panchromatic rmi images were acquired from sol 10 to sol 360 to document the chemcam libs measurements and to characterize soils rocks and rover hardware we show several types of derived imaging products including mosaics of images taken before and after laser shots difference images to enhance the most subtle laser pits merges with color mastcam 100 images micro topography using the z stack technique and time lapse movies the very high spatial resolution of rmi is able to resolve rock textures at sub mm scales which provides clues regarding the origin igneous versus sedimentary of rocks and to reveal information about their diagenetic and weathering evolution in addition to its scientific value over the range accessible by libs 1 7 m we also show that rmi can also serve as a powerful long distance reconnaissance tool to characterize the landscape at distances up to several kilometers from the rover

hydration state of calcium sulfates in gale crater mars identification of bassanite veins abstract in situ analyses reveal the presence of hydrogen within calcium sulfate veins crosscutting the sediments found in gale crater laboratory experiments were performed to calibrate the hydrogen signal measured by laser induced breakdown spectroscopy libs in a range applicable to martian data the analyses indicate that all veins targeted so far at gale consist predominantly of bassanite which most likely formed by dehydration of gypsum this scenario suggests that the percolating water produced gypsum possibly by hydration of anhydrite in aqueous solution and remained at temperatures below 60 c at that time desiccating conditions followed consistent with a hyperarid climate and favored by burial or impacts additionally anhydrite with lesser bassanite has been found by xrd in samples of sediments hosting the veins our result suggests bassanite is likely found in the veins and anhydrite may be more common as a fine grained component within the sediments

structural geology of impact craters abstract the formation of impact craters is a highly dynamic and complex process that subjects the impacted target rocks to numerous types of deformation mechanisms understanding and interpreting these styles of micro meso and macroscale deformation has proved itself challenging for the field of structural geology in this paper we give an overview of the structural inventory found in craters of all size ranges on earth and look into the structures of craters on other planetary bodies structural features are discussed here that are caused by i extremely high pressures and temperatures that occur during the initial passage of the shock wave through the target rock and projectile ii the resulting flow field in the target that excavates and ejects rock materials and iii the gravitationally induced modification of the crater cavity into the final crater form a special focus is put on the effects that low angle impacting bodies have on crater formation we hope that this review will help both planetary scientists and structural geologists understand the deformation processes and resulting structures generated by meteorite impact

evidence for hydraulic fracturing at gale crater mars implications for burial depth of the yellowknife bay formation abstract nasa s curiosity rover identified a formerly habitable environment within strata informally known as the yellowknife bay formation the stratigraphic relationship and thus depositional age of these rocks relative to other geologic units in gale crater is not clear from orbital data alone if part of lower aeolis mons informally known as mount sharp the yellowknife bay rocks have been deeply buried and exhumed prior to 3 2 3 3 ga if part of younger alluvial fan deposits however they likely have never experienced more than 100 m of burial knowledge of burial history can thus constrain the stratigraphic placement of yellowknife bay and the habitable environment preserved therein the mechanics of natural hydraulic fractures observed in mudstone at ykb allow us to evaluate its burial history and imply a minimum burial depth of 1 2 km this is consistent with burial by the entirety of lower mount sharp and a depositional age of 3 6 3 8 ga providing observation based evidence that mount sharp was once much more laterally extensive than its present form rocks of the yellowknife bay formation thus represent the oldest strata that curiosity will encounter during its journey in gale crater and any additional habitable environments discovered along curiosity s future path represent conditions at younger times

abrupt deep sea warming palaeoceanographic changes and benthic extinctions at the end of the palaeocene a remarkable oxygen and carbon isotope excursion occurred in antarctic waters near the end of the palaeocene 57 33 myr ago indicating rapid global warming and oceanographic changes that caused one of the largest deep sea benthic extinctions of the past 90 million years in contrast the oceanic plankton were largely unaffected implying a decoupling of the deep and shallow ecosystems the data suggest that for a few thousand years ocean circulation underwent fundamental changes producing a transient state that although brief had long term effects on environmental and biotic evolution

calcium sulfate veins characterized by chemcam curiosity at gale crater mars the curiosity rover has analyzed abundant light toned fracture fill material within the yellowknife bay sedimentary deposits the chemcam instrument coupled with mastcam and chemcam remote micro imager images was able to demonstrate that these fracture fills consist of calcium sulfate veins many of which appear to be hydrated at a level expected for gypsum and bassanite anhydrite is locally present and is found in a location characterized by a nodular texture an intricate assemblage of veins crosses the sediments which were likely formed by precipitation from fluids circulating through fractures the presence of veins throughout the entire similar to 5 m thick yellowknife bay sediments suggests that this process occurred well after sedimentation and cementation lithification of those sediments the sulfur rich fluids may have originated in previously precipitated sulfate rich layers either before the deposition of the sheepbed mudstones or from unrelated units such as the sulfates at the base of mount sharp the occurrence of these veins after the episodes of deposition of fluvial sediments at the surface suggests persistent aqueous activity in relatively nonacidic conditions

overview of the mars science laboratory mission bradbury landing to yellowknife bay and beyond the mars science laboratory mission reached bradbury landing in august 2012 in its first 500 sols the rover curiosity was commissioned and began its investigation of the habitability of past and present environments within gale crater curiosity traversed eastward toward glenelg investigating a boulder with a highly alkaline basaltic composition encountering numerous exposures of outcropping pebble conglomerate and sampling aeolian sediment at rocknest and lacustrine mudstones at yellowknife bay on sol 324 the mission turned its focus southwest beginning a year long journey to the lower reaches of mt sharp with brief stops at the darwin and cooperstown waypoints the unprecedented complexity of the rover and payload systems posed challenges to science operations as did a number of anomalies operational processes were revised to include additional opportunities for advance planning by the science and engineering teams

mechanical twinning in quartz shock experiments impact pseudotachylites and fault breccias abstract increasing use of diffraction methods to study preferred orientation of minerals has established that quartz in deformed rocks not only displays characteristic c axis orientation patterns but that there is also generally a distinct difference in the orientation of positive and negative rhombs in the trigonal quartz crystal structure positive and negative rhombs are structurally different and particularly negative rhombs e g 01 1 1 are much stiffer than positive rhombs e g 10 1 1 here we focus on the role of mechanical dauphine twinning under stress as a cause of this difference and illustrate with ebsd measurements ubiquitous twinning in quartz bearing rocks subjected to high stresses characteristic twinning is observed in experimentally shocked sandstones and stishovite bearing quartzites from the vredefort meteorite impact site in south africa similar twinning is documented for quartz associated with pseudotachylites from the santa rosa mylonite zone in southern california whereas quartz in underlying ductile mylonites are more or less twin free it suggests that twinning was produced by local seismic stresses that caused fracture and frictional melting on fault surfaces quartz bearing breccias from the safod san andreas fault observatory at depth drilling project also show evidence of twinning and suggest high seismic stresses in the currently creeping segment of the san andreas fault at parkfield from these observations it appears that dauphine twin microstructures can be diagnostic of high local and transient stresses

regional sand injectite architecture as a record of pore pressure evolution and sand redistribution in the shallow crust insights from the panoche giant injection complex california abstract observations on outcrop of a regionally developed sand injectite are used to infer and estimate the pore pressure conditions in the shallow crust that caused the fluidization and injection of tens of cubic kilometres of sand the estimated pore fluid pressures at the base of the injection complex at 1500 m burial depth below a regionally developed shale dominated seal are from 22 26 to 25 08 mpa which respectively correspond to 0 81 and 0 95 lithostatic pressure a theoretical basis for prediction of sand injection is defined and applied to the prediction of pore pressure at the time of sand injection the depth at which seal failure occurred and the density and granular content of the fluidized flow lateral variations in the style and abundance of sandstone intrusions are described and these all fit into a remarkably uniform tripartite division of parent units an intrusive complex and an extrusive complex a sill zone intrusions are dominated by sills occurs in a restricted stratigraphic interval 200 270 m thick location of the base of the sill zone is directly related to the thickness of the overburden and an isobaric surface at the time of sand injection the lithostatic equilibrium surface is defined at the base of the sill zone when the sills formed an extended period of supra lithostatic pressure occurred within the sill zone

the stratigraphy and evolution of lower mount sharp from spectral morphological and thermophysical orbital data sets we have developed a refined geologic map and stratigraphy for lower mt sharp using coordinated analyses of new spectral thermophysical and morphologic orbital data products the mt sharp group consists of seven relatively planar units delineated by differences in texture mineralogy and thermophysical properties these units are 1 3 three spatially adjacent units in the murray formation which contain a variety of secondary phases and are distinguishable by thermal inertia and albedo differences 4 a phyllosilicate bearing unit 5 a hematite capped ridge unit 6 a unit associated with material having a strongly sloped spectral signature at visible near infrared wavelengths and 7 a layered sulfate unit the siccar point group consists of the stimson formation and two additional units that unconformably overlie the mt sharp group all siccar point group units are distinguished by higher thermal inertia values and record a period of substantial deposition and exhumation that followed the deposition and exhumation of the mt sharp group several spatially extensive silica deposits associated with veins and fractures show late stage silica enrichment within lower mt sharp was pervasive at least two laterally extensive hematitic deposits are present at different stratigraphic intervals and both are geometrically conformable with lower mt sharp strata the occurrence of hematite at multiple stratigraphic horizons suggests redox interfaces were widespread in space and or in time and future measurements by the mars science laboratory curiosity rover will provide further insights into the depositional settings of these and other mineral phases

the process of sand injection internal structures and relationships with host strata yellowbank creek injectite complex california u s a abstract the yellowbank creek injectite complex ycic has excellent exposure of the external geometries and internal structures in a large scale sandstone injectite the ycic has an irregular geometry that can be defined neither as a sandstone dike nor as a sill substantial erosion occurred along the margins between the ycic sandstone and host mudstones that includes scoured basal margins and a scalloped upper margin that cuts up to 5 m into the overlying host mudstones erosion of host mudstone has incorporated significant volumes of mudstone clasts into sandstones at the margins of the injectite using microtextural data corrasion is identified as a typical process by which mudstone is eroded during sand injection corrasion occurs when particles of mudstone are either cut or broken from a cohesive bed as the result of high velocity turbulent flow of sand grains acting as tools corrasion together with scouring and the general erosion of the host mudstone imply high velocity turbulent flow conditions and confirm that the fluidized sand had a sufficiently low viscosity during sand injection to allow turbulence internal structures include laminae of more tightly packed sand grains than occur in the surrounding sandstones and are interpreted to have formed by flow and deposition of injecting sands during waning of flow thus reflecting an overall reduction of pore fluid pressure deformation of laminae into folds defines bands which are aligned parallel to the margins of the sandstone the force driving deformation is likely to have been shear stresses induced between the injected sandstone and the more rigid host mudstone the principal style of deformation is hydroplastic oversteepened laminae and pipes are interpreted to have formed due to post sand injection consolidation and resulted in only minor mobilization of sand

regional scale subsurface sand remobilization geometry and architecture an architectural hierarchy of clastic sills is recognized in the panoche giant injection complex in which staggered stepped with erosive top surfaces and multi layered geometries occur in that stratigraphic order upward genetic relationships between parent depositional sand bodies the sand injections a zone of hydraulic fracture and a palaeo sea floor are seen at a scale previously observed only by using seismic data sills and randomly oriented dykes intrude into a hydraulically fractured shale unit above and below which dykes predominate erosive surfaces scallops are identified on sills that along with smaller erosional features record low viscosity turbulent flow during sand injection sand extrusions occur where dykes reach the palaeo sea floor

chemcam passive reflectance spectroscopy of surface materials at the curiosity landing site mars the spectrometers on the mars science laboratory msl chemcam instrument were used in passive mode to record visible near infrared 400 840 nm radiance from the martian surface using the onboard chemcam calibration targets housing as a reflectance standard we developed methods to collect calibrate and reduce radiance observations to relative reflectance such measurements accurately reproduce the known reflectance spectra of other calibration targets on the rover and represent the highest spatial resolution 0 65 mrad and spectral sampling 1 nm visible near infrared reflectance spectra from a landed platform on mars relative reflectance spectra of surface rocks and soils match those from orbital observations and multispectral data from the msl mastcam camera preliminary analyses of the band depths spectral slopes and reflectance ratios of the more than 2000 spectra taken during the first year of msl operations demonstrate at least six spectral classes of materials distinguished by variations in ferrous and ferric components initial comparisons of chemcam spectra to laboratory spectra of minerals and mars analog materials demonstrate similarities with palagonitic soils and indications of orthopyroxene in some dark rocks magnesium rich raised ridges tend to exhibit distinct near infrared slopes the ferric absorption downturn typically found for martian materials at 600 nm is greatly subdued in brushed rocks and drill tailings consistent with their more ferrous nature calcium sulfate veins exhibit the highest relative reflectances observed but are still relatively red owing to the effects of residual dust such dust is overall less prominent on rocks sampled within the blast zone immediately surrounding the landing site these samples were likely affected by the landing thrusters which partially removed the ubiquitous dust coatings increased dust coatings on the calibration targets during the first year of the mission were documented by the chemcam passive measurements as well ongoing efforts to model and correct for this dust component should improve calibration of the relative reflectance spectra this will be useful as additional measurements are acquired during the rover s future examinations of hematite sulfate and phyllosilicate bearing materials near the base of mt sharp that are spectrally active in the 400 840 nm region

opaline silica in young deposits on mars high spatial and spectral resolution reflectance data acquired by the mars reconnaissance orbiter compact reconnaissance imaging spectrometer for mars crism instrument reveal the presence of h 2o and sioh bearing phases on the martian surface the spectra are most consistent with opaline silica and glass altered to various degrees confirming predictions based on geochernicall experiments and models that amorphous silica should be a common weathering product of the basaltic martian crust these materials are associated with hydrated fe sulfates including h 3o bearing jarosite and are found in finely stratified deposits exposed on the floor of and on the plains surrounding the valles marineris canyon system stratigraphic relationships place the formation age of these deposits in the late hesperian or possibly the amazonian implying that aqueous alteration continued to be an important and regionally extensive process on mars during that time

complex reservoir geometries in a deep water clastic sequence gryphon field ukcs injection structures geological modelling and reservoir simulation abstract the balder formation sandstone reservoir of the gryphon field was deposited during the late paleocene early eocene while the background sedimentation comprised pelagic shales and tuffs sediment gravity flows transported sands from the shelf area in the west the crawford ridge acted as a barrier to sediment transport in the east causing the sands to be deposited predominantly as massive sand bodies as flow velocities decreased during burial sand remobilisation and injection occurred possibly localised around faults cored intervals show a range of injection structures from thin cm scale dykes to more massive metre scale chaotic intrusive features the cross cutting nature of the injection structures as observed in core and in seismic sections accounts for the high degree of reservoir connectivity observed in the field a study was undertaken with the objective of constructing a 3d geological model for dynamic reservoir simulation in order to evaluate future development activities in the field as previous purely deterministic models had proven unsuitable the complex depositional and post depositional history of the gryphon field reservoir has resulted in a system for which there is no published analogue to aid in 3d reservoir modelling preliminary stochastic models based on analogues chosen to reflect the reservoir sand body geometries did not match the field production history the fact that both the deterministic and fully stochastic models were unsuitable suggested that a novel approach was required to model this field subsequent models constructed using a combination of stochastic and deterministic models have proven successful in matching the production history of the field and evaluating infill opportunities

armored mud balls and friable sand megaclasts from a complex early pleistocene alluvial fill southwestern morrill county nebraska armored mud balls and friable sand megaclasts occur in exposures of a complex early pleistocene sand and gravel alluvial fill which caps a strath terrace in southwestern morrill county nebraska the mud balls are limited to a tributary arroyo the sand megaclasts occur in sediments deposited along a trunk stream it is possible that the sand megaclasts were transported to the site in a frozen condition

a new stereo topographic map of io implications for geology from global to local scales we use voyager and galileo stereo pairs to construct the most complete stereo digital elevation model dem of io assembled to date controlled using galileo limb profiles given the difficulty of applying these two techniques to io due to its anomalous surface albedo properties we have experimented extensively with the relevant procedures in order to generate what we consider to be the most reliable dems our final stereo dem covers 75 of the globe and we have identified a partial system of longitudinally arranged alternating basins and swells that correlates well to the distribution of mountain and volcano concentrations we consider the correlation of swells to volcano concentrations and basins to mountain concentrations to imply a heat flow distribution across io that is consistent with the asthenospheric tidal heating model of tackley et al 2001 the stereo dem reveals topographic signatures of regional scale features including loki patera ra patera and the tvashtar paterae complex in addition to previously unrecognized features including an 1000 km diameter depression and a 2000 km long topographic arc comprising mountainous and layered plains material

high manganese concentrations in rocks at gale crater mars the surface of mars has long been considered a relatively oxidizing environment an idea supported by the abundance of ferric iron phases observed there however compared to iron manganese is sensitive only to high redox potential oxidants and when concentrated in rocks it provides a more specific redox indicator of aqueous environments observations from the chemcam instrument on the curiosity rover indicate abundances of manganese in and on some rock targets that are 1 2 orders of magnitude higher than previously observed on mars suggesting the presence of an as yet unidentified manganese rich phase these results show that the martian surface has at some point in time hosted much more highly oxidizing conditions than has previously been recognized

mineralogy and stratigraphy of the gale crater rim wall and floor units the curiosity rover has detected diverse lithologies in float rocks and sedimentary units on the gale crater floor interpreted to have been transported from the rim to understand their provenance we examine the mineralogy and geology of gale s rim walls and floor using high resolution imagery and infrared spectra while no significant differences in bedrock spectral properties were observed within most thermal emission imaging system and compact reconnaissance imaging spectrometer for mars crism scenes some crism scenes of rim and wall rocks showed olivine bearing bedrock accompanied by fe mg phyllosilicates hydrated materials with 2 48 m absorptions in gale s eastern walls are spectrally similar to the sulfate unit in mount sharp aeolis mons sedimentary strata on the gale floor southwest of the landing site likely coeval with the bradbury units explored by curiosity also are hydrated and or have fe mg phyllosilicates spectral properties of these phyllosilicates differ from the al substituted nontronite detected by crism in mount sharp suggesting formation by fluids of different composition geologic mapping of the crater floor shows that the hydrated or hydroxylated materials are typically overlain by spectrally undistinctive erosionally resistant cliff forming units additionally a 4 km impact crater exposes 250 m of the gale floor including finely layered units no basement rocks are exposed thus indicating sedimentary deposits 250 m beneath strata studied by curiosity collectively the data indicate substantial sedimentary infill of gale crater including some materials derived from the crater rim lowermost thin layers are consistent with deposition in a lacustrine environment interbedded hydrated hydroxylated units may signify changing environmental conditions perhaps in a drying or episodically dry lake bed

traces of evaporites in upper cretaceous lacustrine deposits of korea origin and paleoenvironmental implications abstract diverse types of halite and sulfate evaporite traces occur in the upper cretaceous lacustrine deposits of the jindong formation and the jangdong tuff in korea in which dinosaur tracks are common the halite traces usually occur as casts or moulds and they include traces of primary halite hoppers primary and intrasedimentary skeletal halite and intrasedimentary tiny halite the sulfate traces occur as intrasedimentary and displacive casts filled with sediments and sparry calcite and the casts occur as diverse modes from single crystal casts through nodular aggregates to massive aggregates some aggregates of the sulfate casts are aligned in crack pattern and selective occurrence of the laths in ripple troughs are observed soluble sulfate evaporite minerals such as gypsum glauberite or mirabilite are probable for the precursors of these traces these halite and sulfate traces are interpreted to have been formed in a saline lake and mudflats it is interpreted that meteoric water was responsible for the evaporite precipitation in the jindong lake and jangdong lake recycled brine produced by the repeated dissolution of evaporites might contribute to the evaporite precipitation in the paleo jindong lake and the paleo jangdong lake the development of saline lake deposits in the jindong formation and the jangdong tuff suggests that the southern part of the korean peninsula remained an inland continental area during the cretaceous resulting in semi arid paleoclimatic condition due to an orographic effect by the location of the korean peninsula on continental margin in mid latitude with topographic barriers during the cretaceous the occurrence of dinosaur tracks in the lake margin deposits of saline lake with frequent inflow of dilute meteoric water suggests that upper cretaceous dinosaurs inhabiting lakes on the korean peninsula might have drunken brackish water

first detection of fluorine on mars implications for gale crater s geochemistry volatiles and especially halogens f and cl have been recognized as important species in the genesis and melting of planetary magmas data from the chemical camera instrument on board the mars science laboratory rover curiosity now provide the first in situ analyses of fluorine at the surface of mars two principal f bearing mineral assemblages are identified the first is associated with high aluminum and low calcium contents in which the f bearing phase is an aluminosilicate it is found in conglomerates and may indicate petrologically evolved sources this is the first time that such a petrologic environment is found on mars the second is represented by samples that have high calcium contents in which the main f bearing minerals are likely to be fluorapatites and or fluorites fluorapatites are found in some sandstone and may be detrital while fluorites are also found in the conglomerates possibly indicating low t alteration processes

diagenetic nonevaporative origin for gypsum paleoenvironmental interpretations commonly cite the occurrence of gypsum associated with nonfossiliferous redbeds as evidence for arid conditions and high evaporation rates such interpretations ignore the common occurrence of gypsum in gossan on weathered black shale surfaces and especially in pleistocene glacial deposits glaciolacustrine deltaic sequences in ohio contain abundant large gypsum crystals that formed diagenetically as a result of oxidation of sulfides by calcium rich oxidizing ground water crystals display two forms related to the host sediment euhedral tabular crystals occur in pliable prodelta mud whereas bladed dovetail gypsum sand crystals occur in grain supported delta front sand the diagenetic non evaporative model could explain the formation of gypsum in numerous sedimentary sequences dune tidal flat beach lagoon reef lagoon deltaic and barrier bar lagoon massive extensive sulfate accumulations probably formed under arid conditions however the nonevaporative diagenetic model should be considered in the interpretation of scattered gypsum crystals and thin gypsum crusts

sediment flow and deformation sfd layers evidence for intrastratal flow in laminated muddy sediments of the triassic osawa formation northeast japan abstract thin chaotic layers containing abundant intraformational mud clasts are found in the offshore laminated mudstone of the triassic osawa formation in northeast japan the geometry and internal structures of the layers are somewhat similar to those of slump slide or debris flow deposits however the layers have both upper and lower erosional contacts projections of host sediments and mud clasts with planed surfaces are identified beneath the upper contact of the layers closely packed sheet form or ellipsoidal mud clasts are embedded in a poorly sorted fine to coarse grained sandy matrix some mud clasts are tightly folded or show imbricated stacking internal layering structures are also well developed in the layers the above features strongly suggest soft sediment deformation as horizontal displacement of sand and mud under buried conditions here we term these layers sediment flow and deformation sfd layers deformation layers with similar attributes have been identified by some prior authors as in the case of flow of liquefied and or fluidized host sand and clastic sill intrusion however the sfd layers described herein have more complex structure indicating advanced deformation occurrence of the sfd layers is stratigraphically limited to the uppermost part of the osawa formation which is overlain by sand rich submarine fan deposits the fukkoshi formation it suggests that the stress field caused by differential loading of overlying deposits facilitated intrastratal flow and sill intrusions of sand the vertical confinement was also controlled by the anisotropy in physical properties such as tensile strength of laminated mud and or conditions of gentle slope

seismic imaging of complex geometry forward modeling of sandstone intrusions abstract sandstone intrusions form large bedding discordant sandstones that intruded into finer grained less permeable host strata they form naturally sand propped hydraulic fractures that constitute a connected network of permeable conduits through which fluids escape to the earth s surface saucer shaped sandstone intrusions are among the largest volume intrusions and are commonly resolved on seismic data outcrop analogues of seismically resolved saucers shaped intrusions reveal that many attendant intrusions in particular dikes are undetected in seismic data seismic forward modeling of a detailed outcrop description of a saucer shaped intrusion demonstrates that intrusions steeper than 45 are undetected and that up to 40 of the entire volume of sandstone intrusions is not seismically imaged wedge geometry associated with discordant contacts between different lithologies causes constructive and destructive amplitude interference creating imaging artefacts of sandstone thickness and geometry comparison of the outcrop seismic models with 3d seismic data from volund oilfield demonstrate both the similarity of the saucer shaped intrusions and the distribution and quantity of dikes that may be undetected ca 78 using subsurface data lack of detection of dikes has direct implications on the valuation of upward migration of fluids and an overestimation of seal capacity this therefore has major implications when using seismic data to evaluate waste sequestration or to execute hydrocarbon or groundwater exploration and production

constraints on iron sulfate and iron oxide mineralogy from chemcam visible near infrared reflectance spectroscopy of mt sharp basal units gale crater mars relative reflectace point spectra 400 840 nm were acquired by the chemistry and camera chemcam instrument on the mars science laboratory msl rover curiosity in passive mode no laser of drill tailings and broken rock fragments near the rover as it entered the lower reaches of mt sharp and of landforms at distances of 2 8 km freshly disturbed surfaces are less subject to the spectral masking effects of dust and revealed spectral features consistent with the presence of iron oxides and ferric sulfates we present the first detection on mars of a 433 nm absorption band consistent with small abundances of ferric sulfates corroborated by jarosite detections by the chemistry and mineralogy chemin x ray diffraction instrument in the mojave telegraph peak and confidence hills drilled samples disturbed materials near the bonanza king region also exhibited strong 433 nm bands and negative near infrared spectral slopes consistent with jarosite chemcam passive spectra of the confidence hills and mojave drill tailings showed features suggestive of the crystalline hematite identified by chemin analyses the windjana drill sample tailings exhibited flat low relative reflectance spectra explained by the occurrence of magnetite detected by chemin passive spectra of bonanza king were similar suggesting the presence of spectrally dark and neutral minerals such as magnetite long distance spectra of the hematite ridge feature 3 5 km from the rover exhibited features consistent with crystalline hematite the bagnold dune field north of the hematite ridge area exhibited low relative reflectance and near infrared features indicative of basaltic materials olivine pyroxene light toned layers south of hematite ridge lacked distinct spectral features in the 400 840 nm region and may represent portions of nearby clay minerals and sulfates mapped with orbital near infrared observations the presence of ferric sulfates such as jarosite in the drill tailings suggests a relatively acidic environment likely associated with flow of iron bearing fluids associated oxidation and or hydrothermal leaching of sedimentary rocks combined with other remote sensing data sets mineralogical constraints from chemcam passive spectra will continue to play an important role in interpreting the mineralogy and composition of materials encountered as curiosity traverses further south within the basal layers of the mt sharp complex

distinguishing depositional setting for sandy deposits in coastal landscapes using grain shape abstract several methods exist that use sediment properties to characterize depositional setting and related mechanisms of transport including analysis of grain size distributions sediment petrology micromorphology and grain structure techniques that rely on electron or optical microscopy produce results with varying degrees of success and applicability here a new method is presented and used to differentiate between littoral and eolian sands that were extracted from recently formed landforms as well as landforms that are from mid to late holocene in age the method utilizes a standard optical microscope with a mounted digital camera paired with freely available software imagej to characterize grain shape parameters the method was tested on nearly 6000 sand grains from samples with varied transport histories and it was found that grain solidity was the most distinguishable characteristic between eolian and littoral samples differentiating them 86 of the time for calibration samples the method was used to correctly identify the mechanism of transport for 76 of the samples patterns in the results indicated that this method could be extended to link potential sediment sources to various depositional basins and future work includes testing the method in areas with a different mineralogy and or landscape history

sandstone extrusions and slope channel architecture and evolution mio pliocene monterey and capistrano formations dana point harbor orange county california u s a abstract the miocene monterey formation and deepwater channels of the mio pliocene capistrano formation crop out at dana point harbor california and are locally separated by a series of extruded sandstone bodies stratigraphic columns photo panels and high resolution lidar data are used to describe the stratigraphy of the 840 m wide 30 m thick exposure the studied exposure contains 1 a lower unit composed of monterey slope mudstone 2 an up to 13 m thick discontinuous middle unit of structureless sandstone bodies and 3 an upper sandstone unit composed of the laterally and vertically stacked breccia conglomerate and sand filled channels of the capistrano formation several observations collectively suggest that the structureless sandstone bodies in the middle unit are remobilized 1 the lower mudstone unit contains centimeter to meter scale injections of structureless poorly sorted coarse grained sandstones 2 the facies in the middle sandstone unit are identical to the injected sandstones facies observed in the lower mudstone unit 3 the structureless sandstone bodies of the middle unit form disconnected bodies below the upper sandstone unit and have an average aspect ratio of 4 1 whereas the capistrano channels have an aspect ratio greater than 10 1 4 quartz and feldspar grains in the injected sandstone of the lower unit and the structureless sandstone of the middle unit are fractured 5 the structureless sandstone bodies of the middle unit contain meter scale angular mudstone clasts of composition similar to that of the monterey mudstones 6 these clasts contain internal sandstone injections and are deformed 7 the monterey strata around the structureless sandstone bodies display distinct variations of strike and dip relative to the regional trend the remobilized sandstone bodies forming the middle unit are interpreted as extruded sandstone bodies that incorporated large mudstone clasts rafts during the migration from a deep sand source interpreted as being a lower sandy monterey interval these sand extrusions were emplaced at the seafloor in multiple phases following slope channel incision and preceding channel fill deposits these extruded fluidized sands triggered local syndepositional deformation of the channel fills in the form of large load structures the processes that caused the source sands to fluidize are interpreted to be related to deep fluid migration toward a structural high located below the study area the mechanism triggering the upward migration of sand is likely related to slope channel incision

chemical divides and evaporite assemblages on mars assemblages of evaporite minerals record detailed physical and chemical characteristics of ancient surficial environments accordingly newly discovered regions of saline minerals on mars are high priority targets for exploration the chemical divide concept of evaporite mineral formation is used successfully to predict evaporite mineralogy and brine evolution on earth however basaltic weathering largely controls fluid compositions on mars and the robust predictive capabilities of terrestrial chemical divides cannot be used to interpret martian evaporites here we present a new chemical divide system that predicts evaporite assemblages identified in snc type meteorites ancient evaporites discovered on meridiani planum by the opportunity rover and mars express omega data we suggest that a common fluid type that has been buffered to different ph levels by basaltic weathering controls the variability among martian evaporite assemblages and that evaporite mineralogy and brine evolution is essentially established by the initial composition of the dilute evaporating fluid b 2005 elsevier b v all rights reserved

a habitable fluvio lacustrine environment at yellowknife bay gale crater mars the curiosity rover discovered fine grained sedimentary rocks which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy this aqueous environment was characterized by neutral ph low salinity and variable redox states of both iron and sulfur species carbon hydrogen oxygen sulfur nitrogen and phosphorus were measured directly as key biogenic elements by inference phosphorus is assumed to have been available the environment probably had a minimum duration of hundreds to tens of thousands of years these results highlight the biological viability of fluvial lacustrine environments in the post noachian history of mars

effects of temperature and humidity upon the transport of sedimentary particles by wind aeolian transport of sedimentary particles is a well recognized phenomenon in cold regions but the effect of low temperature t and specific humidity q upon particle entrainment has not previously been investigated this study reports on wind tunnel experiments 12 c t 32 c and 1 g kg 1 q 10 g kg 1 that suggest the aerodynamic drag required to entrain sand sized particles can be 30 lower in cold or high latitude settings as compared to hot deserts for any given regional wind velocity this effect will increase the wind strength index and thereby the proportion of time a surface is active at low temperature

effects of crystallographic anisotropy on fracture development and acoustic emission in quartz 1 transgranular microcracking is fundamental for the initiation and propagation of all fractures in rocks the geometry of these microcracks is primarily controlled by the interaction of the imposed stress field with the mineral elastic properties however the effects of anisotropic elastic properties of minerals on brittle fracture are not well understood this study examines the effects of elastic anisotropy of quartz on the geometry of brittle fracture and related acoustic emissions ae developed during indentation experiments on single crystals at ambient pressure and temperature a hertzian cone crack developed during blunt indentation of a single crystal of flawless brazilian quartz parallel to the c axis shows geometric deviation away from predictions based on the isotropic case consistent with trigonal symmetry the visible cone crack penetration depth varies from 3 to 5 mm and apical angle from 53 to 40 electron backscatter diffraction ebsd mapping of the crack tip shows that fracturing initiates along a 40 m wide process zone comprising damage along overlapping en echelon high index crystallographic planes shown by discrete bands of reduced electron backscatter pattern ebsp quality band contrast coalescence of these surfaces results in a stepped fracture morphology monitoring of ae during indentation reveals that the elastic anisotropy of quartz has a significant effect on ae location and focal mechanisms ninety four ae events were recorded during indentation and show an increasing frequency with increasing load they correspond to the development of subsidiary concentric cracks peripheral to the main cone crack the strong and complex anisotropy in seismic velocity 28 vp 43 vs with trigonal symmetry resulted in inaccurate and high uncertainty in ae locations using geiger location routine with an isotropic velocity model this problem was overcome by using a relative master event location algorithm that only requires a priori knowledge of the velocity structure within the source volume the ae location results correlate reasonably well to the extent of the observed cone crack decomposition of ae source mechanisms of the geiger relocated events shows dominantly end member behavior between tensile and compressive vector dipole events with some double couple dominated events and no purely tensile or compressive events the same events located by the master event algorithm yield greater percentage of vector dipole components and no double couple events indicating that ae source mechanism solutions can depend on ae location accuracy and therefore relocation routine that is utilized calculations show that the crystallographic anisotropy of quartz causes apparent deviation of the moment tensors away from double couple and pure tensile compressive sources consistent with the observations preliminary modeling of calcite anisotropy shows a response distinct from quartz indicating that the effects of anisotropy on interpreting ae are complex and require detailed further study

paleoclimate of mars as captured by the stratigraphic record in gale crater a kilometers thick sedimentary sequence in gale crater exhibits stratigraphic changes in lithology that are consistent with transitions in aqueous and climatic conditions purported to be global in scale the sequence is divided into two formations where the lower formation exhibits a net transition in mineralogy from clay sulfate to sulfate oxide assemblages and is separated from the overlying upper formation by an erosional unconformity superposition and crater counts suggest strata in the lower formation lie along the noachian hesperian time stratigraphic boundary whereas beds in the upper formation which lack signatures indicative of clay minerals or sulfates are thinner more regularly spaced and clearly younger the observed stratigraphic trends are consistent with the rocks at gale crater recording a global transition from a climate favorable to clay mineral formation to one more favorable to forming sulfates and other salts

lithified armored mud balls of the lower jurassic turners falls sandstone north central massachusetts a unique occurrence of lithified fluvial armored mud balls has been found in the lower jurassic turners falls sandstone of north central massachusetts the long axes of the 55 examples range from 2 5 to 30 cm which agrees with previous studies of modern armored mud balls their triaxial ellipsoidal shapes differ from the usual spheroid shapes of modern examples it is inferred that they formed quickly after only a few hundred meters of transport in a distal fan environment

diagenetic silica enrichment and late stage groundwater activity in gale crater mars diagenetic silica enrichment in fracture associated halos that crosscut lacustrine and unconformably overlying aeolian sedimentary bedrock is observed on the lower north slope of aeolis mons in gale crater mars the diagenetic silica enrichment is colocated with detrital silica enrichment observed in the lacustrine bedrock yet extends into a considerably younger unconformably draping aeolian sandstone implying that diagenetic silica enrichment postdates the detrital silica enrichment a causal connection between the detrital and diagenetic silica enrichment implies that water was present in the subsurface of gale crater long after deposition of the lacustrine sediments and that it mobilized detrital amorphous silica and precipitated it along fractures in the overlying bedrock although absolute timing is uncertain the observed diagenesis likely represents some of the most recent groundwater activity in gale crater and suggests that the timescale of potential habitability extended considerably beyond the time that the lacustrine sediments of aeolis mons were deposited

origin of precambrian iron formations in the lake superior region the precambrian banded cherty iron formations in the lake superior region were deposited on broad continental shelves and deposits of the supratidal intertidal and subtidal zones can be recognized in the well known facies of the iron formations the supratidal deposits were primarily calcitic aragonitic and sideritic muds other minerals in order of decreasing abundance may have been gypsum anhydrite ankerite dolomite quartz apatite and halite intraclasts were produced by desiccation granulation and some of this material was redeposited in the intertidal and subtidal zones the intertidal zone was characterized by the development of extensive algal reefs and digital sized and larger stromatolitic mounds desiccation granulation and tidal rip of mineralized stromatolites further added to the accumulation of intraclasts the intertidal zone was the domain of granules that were derived by abrasion and rounding of intraclasts the original mineralogy of the intertidal deposits was similar to that of the supratidal zone however because of photosynthesis the sea water was oxygenated lozenge shaped grains are considered to be secondary silicified and iron oxide replicates of original gypsum crystals and by comparison with recent evaporites some anhydrite and halite may also have been present the deposits of the intertidal and subtidal zones are considered to be comparable to the present day abu dhabi complex in the persian gulf spherical microstructures are abundant and well preserved in the chert of the subtidal deposits pyrite which characterizes these deposits probably was formed largely by the bacterial reduction of sulfate derived from the intertidal zone the laminations in the iron formations resulted from several causes that were controlled by chemical and mechanical processes such as the rates and localization of the precipitation of calcitic aragonitic and sideritic muds and the mechanical breakup and redistribution of these sediments as sand silt and mud these processes resulted in compositional and textural laminations the diversity of the banded cherty iron formations recognized in the different facies then can be explained largely in the diagenetic changes the large scale pervasive diagenetic changes were the replacement of calcite and aragonite by chert and the formation of iron silicates by the reactions between ionic silica and siderite and iron bearing dolomite vein like structures and the development of magnetite along stylolites indicate mobility of iron in late diagenetic stages and iron organic chelates are suggested to account for the mobility depending on the composition of the laminae and the chemical environment silicification during diagenesis produced the hematite magnetite siderite pyrite and mixed mineral facies

facies and flow regimes of sandstone hosted columnar intrusions insights from the pipes of kodachrome basin state park sandstone hosted intrusions are found in a wide variety of environments but remain poorly understood compared with their mudstone hosted counterparts in particular they remain largely unrecognized in the subsurface in part because they are problematic to image in seismic data this study reports on the facies and fluid flow associated with a 20 000 km3 sandstone intrusion province in utah usa forming a small portion of this intrusion province the intrusions cropping out in kodachrome basin state park display a very wide array of facies and morphologies factors which would make their identification in core a significant challenge remobilized sediment is shown to have been injected at least 200 m vertically from its source with flow prolonged enough to concentrate heavy minerals in placer style deposits at the pipe margins evidence for lateral pipe migration and for associated broader fluidization regions is also presented a new approach to estimating flow parameters in injectites is implemented herein and indicates that previous work has overestimated velocities and flow reynolds numbers by up to two orders of magnitude flow modelling suggests turbulent flow in the pipes that is consistent with field observations of erosive margins and chaotic internal structures post emplacement these pipes remained as long term fluid conduits as revealed by their diagenetic history focussing and facilitating flow of extraformational fluids despite the relatively high porosity and permeability of the aeolian host strata

evidence for platy hematite grains in sinus meridiani mars 1 midinfrared 1600 200 cm 1 spectral data received from the mars global surveyor thermal emission spectrometer mgs tes have provided evidence for a large hematite bearing fe2o3 deposit in sinus meridiani mars we report here the results of a laboratory spectroscopic investigation of 24 hematite samples including polycrystalline hand samples massive and schistose textures single crystal hand samples and particle size fractions single crystal and polycrystalline discrete particles laboratory midinfrared analyses of crystallographically oriented hematite samples suggest that the hematite emission in sinus meridiani sm is predominantly from the crystallographic c face of hematite this observation implies the presence of platy hematite particles with the plate face being the crystallographic c face the observations are consistent with a formational model where the platy gray hematite originated as an iron oxide chemically precipitated from fe rich aqueous and or hydrothermal solutions on early mars that was buried recrystallized to platy hematite and subsequently reexposed as lenses of schistose hematite in a friable consolidated stratigraphic unit unconsolidated platy hematite particles are also likely to be present as a physical weathering product of the schistose hematite lenses

a tidal origin for coarsening upward sequences above two wilcox lignites in east texas conventional palaeogeographic reconstructions show a large river system occupying the east texas embayment during the deposition of the wilcox group coarsening upward sequences above wilcox lignites in east texas have been interpreted as floodplain splays however the bedding types sedimentary structures and shallow scour surfaces in a coarsening upward sequence above the main seam at the martin lake mine in panola county indicate deposition in water stirred by tidal and wave activity the bedding types include sand streaks in mud and lenticular wavy and flaser bedding the sedimentary structures include abundant wave ripple lamination and large scale crossbeds with thin closely spaced mud drapes these crossbeds suggest traction currents of short duration alternating with periods of slack water pollen from broadleaf hardwood trees is the most common element of the palynoflora from the coarsening upward sequence at the mine the upper reaches of riverine estuaries along the se coast of the united states provide a modern analogue for the environment of deposition of the wilcox sediments at the martin lake mine here tidal currents extend inland to places where freshwater aquatic plants and forests border the estuaries the same bedding types and sedimentary structures that occur in the sediments at the martin lake mine occur in a coarsening upward sequence above a lignite at the big brown mine in freestone county recognition of the tidal origin of the coarsening upward sequences suggests an embayed coast or a shoreline within the east texas embayment during the deposition of the strata above the lignites

observation of 5 wt zinc at the kimberley outcrop gale crater mars zinc enriched targets have been detected at the kimberley formation gale crater mars using the chemistry camera chemcam instrument the zn content is analyzed with a univariate calibration based on the 481 2 nm emission line the limit of quantification for zno is 3 wt at 95 confidence level and 1 wt at 68 confidence level the limit of detection is shown to be around 0 5 wt as of sol 950 12 targets on mars present high zno content ranging from 1 0 wt to 8 4 wt yarrada sol 628 those zn enriched targets are almost entirely located at the dillinger member of the kimberley formation where high mn and alkali contents were also detected probably in different phases zn enrichment does not depend on the textures of the rocks coarse grained sandstones pebbly conglomerates and resistant fins the lack of sulfur enhancement suggests that zn is not present in the sphalerite phase zn appears somewhat correlated with na2o and the chemcam hydration index suggesting that it could be in an amorphous clay phase such as sauconite on earth such an enrichment would be consistent with a supergene alteration of a sphalerite gossan cap in a primary siliciclastic bedrock or a possible hypogene nonsulfide zinc deposition where zn fe mn would have been transported in a reduced sulfur poor fluid and precipitated rapidly in the form of oxides

a hematite bearing layer in gale crater mars mapping and implications for past aqueous conditions oversampled compact reconnaissance imaging spectrometer for mars crism visible and near infrared hyperspectral data over mount sharp in gale crater mars were used to generate spatially sharpened maps of the location of red crystalline hematite within the uppermost stratum of an 6 5 km long ridge on the mound s northern flank finely layered strata underlie the ridge to the north and have dips consistent with the nearby mount sharp sedimentary sequence fe mg smectites are exposed in a valley to the south of the ridge emplacement of the hematite is hypothesized to result either from exposure of anoxic fe 2 rich groundwater to an oxidizing environment leading to precipitation of hematite or its precursors or from in place weathering of precursor silicate materials under oxidizing conditions these hypotheses and implications for habitability will be testable with in situ measurements by the mars rover curiosity when it reaches mount sharp

hybrid event bed character and distribution linked to turbidite system sub environments the north apennine gottero sandstone north west italy this study documents the character and occurrence of hybrid event beds deposited across a range of deep water sub environments in the cretaceous palaeocene gottero system north west italy detailed fieldwork 5200 m of sedimentary logs has shown that hybrid event beds are most abundant in the distal confined basin plain domain 31 of total thickness in more proximal sectors hebs occur within outer fan and mid fan lobes up to 15 of total thickness whereas they are not observed in the inner fan channelised area six hybrid event bed types heb 1 to heb 6 were differentiated mainly on basis of the texture of their muddier and chaotic central division h3 the confined basin plain sector is dominated by thick max 9 57 m average 2 15 m and tabular hybrid event beds heb 1 to heb 4 their h3 division can include very large substrate slabs evidence of extensive auto injection and clast break up and abundant mudstone clasts set in a sandy matrix dispersed clay ca 20 these beds are thought to have been generated by highly energetic flows capable of delaminating the sea floor locally and carrying large rip up clasts for relatively short distances before arresting the unconfined lobes of the mid fan sector are dominated by thinner average 0 38 m hybrid event beds heb 5 and heb 6 their h3 divisions are characterised by floating mudstone clasts and clay enriched matrices dispersed clay 25 with hydraulically fractionated components mica organic matter and clay flocs these hybrid event beds are thought to have been deposited by less energetic flows that underwent early turbulence damping following incorporation of mud at proximal locations and by segregation during transport although there is a tendency to look to external factors to account for hybrid event bed development systems like the gottero imply that intrabasinal factors can also be important specifically the type of substrate available muddy or sandy and where and how erosion is achieved across the system producing specific hybrid event bed expressions and facies tracts this article is protected by copyright all rights reserved

most mars minerals in a nutshell various alteration phases formed in a single environment in noctis labyrinthus 1 a closed depression in the noctis labyrinthus region of mars at 10 4 s 98 6 w believed to have formed in the late hesperian holds an inner pit partially filled with several hundred meters of stratified material compact reconnaissance imaging spectrometer for mars crism visible near infrared reflectance data reveal signatures of numerous hydrated minerals including halloysite kaolinite fe smectite si oh bearing phases and fe sulfates polyhydrated monohydrated and hydroxylated types including jarosite we use crism data high resolution imagery hirise and hrsc high resolution stereo camera derived elevation to analyze the morphology composition and stratigraphy of these materials we propose an alteration sequence including formation of acid sulfate solutions from groundwater and magmatic sulfur which then locally altered the basaltic bedrock and layered sediments mainly deposited from volcanic tephra forming fe smectite and fe sulfates the mineral variability can mostly be explained by local variations in the ph of the altering fluids with original acidity being buffered by dissolution of primary minerals and by variable fluid input and evaporation and or freezing rates resulting in various water rock ratios this site shows local formation of almost all classes of minerals identified thus far on mars without invoking global conditions processes related to local volcanic activity and associated hydrothermalism were able to produce during an era in which the climate is believed to have been cold a large variety of hydrated minerals this study highlights the importance of the geological setting of hydrated minerals in the understanding of mars geologic and climatic evolution

evolution of late triassic rift basin evaporites passaic formation newark basin eastern north america the passaic formation of the late triassic newark supergroup is 2700 m thick and was deposited in series of wide deep to shallow lacustrine environments in the newark rift basin eastern north america the passaic formation can be divided into lower middle and upper sections based on depositional structures composition and the distribution and morphology of its evaporites evaporites formed as a result of syndiagenetic cementation and or displacive processes evaporitive minerals now include gypsum and anhydrite although other mineral species such as glauberite may have originally existed most of the evaporites of the passaic formation occur within massive red mudstone and siltstone lithologies in the form of diffuse cements void fillings euhedral crystals crystal clusters and nodules these evaporites grew displacively within the fine siliciclastic matrix as a result of changes in the hydrochemical regimes of the rift basin a well developed upward increase in the amount of evaporite material is present in the passaic formation this resulted from 1 long term progressive increase in aridity and 2 significant increase in evaporation surface area of the basin during its tectonic evolution a nonmarine source for the evaporites is evident from the isotopic data sulphate 34s ranges from 11 to 3 3 cdt while 18o ranges from 15 1 to 20 9 smow indicating derivation from early diagenetic oxidation of organic sulphur and pyrite within the organic rich lacustrine deposits the 87sr 86sr ratios in sulphate are radiogenic average 0 71211 showing the interaction of basin waters with detrital components and that the newark basin was isolated from the world ocean most of the original evaporites show evidence of diagenetic change to polycrystalline and polymineralic pseudomorphs now filled with recrystallized coarse grained anhydrite 1 3 mm size and low temperature albite homogenization temperatures of fluid inclusions within the coarse grained anhydrite indicate crystallization temperatures for anhydrite in the range of 150 to 280 c such elevated temperatures resulted from circulation of hot water in the basin later exhumation of these rocks caused partial to total replacement of anhydrite by gypsum in the upper part of the section the resulting increase in volume due to hydration of anhydrite at shallow depths also emplaced non evaporative satin spar veins fibrous gypsum along bedding planes and in fractures while the local geology of the newark rift basin controlled the distribution of facies the sedimentological development of the passaic formation evaporites resulted from the world wide climatic aridity that prevailed during the late triassic because the newark basin sequence was only covered with about 3 km of sedimentary overburden that correspond to about 100 c and hence suggests that evaporites have experienced alteration by hot fluids 5 as the triassic marks the greatest evaporite formation world wide and profound sense of parched continentality throughout the world existed before the final break up of the pangea the passaic formation evaporites are an example of the influence of these palaeoclimatic conditions at the eastern margin of north america

palaeo environment in an ancient low latitude arid lacustrine basin with loessite the smith bank formation early triassic in the central north sea uk continental shelf acknowledgements this work was conducted as part of the triassic mudstones joint industry project which was sponsored by bp conocophillips eon e p esso exploration and production uk limited gdf suez e p uk ltd jx nippon maersk oil shell and total the guidance of prof steve hillier of the james hutton institute in quantitative mineralogical analysis is acknowledged with gratitude dr stuart jones and an anonymous referee are thanked for their incisive and constructive reviews that significantly helped in the revision of the manuscript

in situ evidence for an ancient aqueous environment at meridiani planum mars sedimentary rocks at eagle crater in meridiani planum are composed of fine grained siliciclastic materials derived from weathering of basaltic rocks sulfate minerals including magnesium sulfate and jarosite that constitute several tens of percent of the rock by weight and hematite cross stratification observed in rock outcrops indicates eolian and aqueous transport diagenetic features include hematite rich concretions and crystal mold vugs we interpret the rocks to be a mixture of chemical and siliciclastic sediments with a complex diagenetic history the environmental conditions that they record include episodic inundation by shallow surface water evaporation and desiccation the geologic record at meridiani planum suggests that conditions were suitable for biological activity for a period of time in martian history

microcracks in rocks a review abstract in the past decade the number of studies about microcracks in rocks has rapidly increased this review of recent work concentrates on microcracks in rock as separate entities emphasizing microcrack morphogenesis kinematics dynamics population statistics and observational techniques cracks are produced when the local stress exceeds the local strength the local stress may be augmented by twin lamellae interactions kink bands and deformation lamellae stress concentrations at grain boundary contacts and around intracrystalline cavities local strength may be reduced along cleavage planes along grain boundaries and along any internal surface as a result of corrosion by chemically active fluids dislocations appear not to be a significant factor for crack nucleation below about 500 c in silicates spatial and temporal changes in temperature can also induce microcracking as a result of differential thermal expansion between grains with different thermoelastic moduli and thermal conductivities the amount of quartz in the rock has a significant effect on thermally induced microcracks because of its large and variable thermal expansivity the application of hydrostatic pressure between 100 and 200 mpa effectively closes most cracks but the closure may not be uniform if crack wall asperities exist hydrostatic pressure appears to stabilize cracks and make crack growth more difficult the number and average size of mechanically induced microcracks is greater in rock deformed at higher pressures the application of a deviatoric stress field on the boundaries of a rock mass results on a microscopic scale in a very complex stress system which greatly affects nucleation and propagation paths the relative amount of intragranular and intergranular cracking appears to depend upon mineralogy rock type and stress state the vast majority of stress induced microcracks in rocks appear to be extensional statistically they are predominantly oriented within 30 of the macroscopic maximum stress direction crack densities increase as macroscopic deviatoric stress increases above a threshold level crack size distributions may be either lognormal or exponential fracture in rock under compressive boundary loads is a result of the coalescence of many microcracks not the growth of a single crack some crack configurations are more favorable for coalescence than others as deviatoric stress increases and rock failure is approached the microcrack population changes spatially from random to locally intense zones of cracking away from the fault the crack density dies off rapidly to the background level a few grains away under lesser deviatoric stresses slow subcritical microcrack growth can occur as a result of stress aided corrosion at the crack tip the rate governing mechanism may be either the chemical reaction rate or the rate at which water can get to the crack tip important details still remain to be worked out