searching at the right time of day evidence for aqueous minerals in columbus crater with tes and themis data the primary objective of the thermal emission imaging system themis experiment which has been in orbit at mars since early 2002 is to identify minerals associated with hydrothermal and subaqueous environments data from themis have supported the presence of clays silica rich deposits and chlorides but has not before provided definitive evidence for the presence of sulfates this is an especially puzzling result given that sulfates have been extensively identified with other instruments at mars if present sufficiently exposed and in high enough abundances such minerals should be detectable in orbital thermal infrared spectra at the resolution of themis the extended mission proposal for themis on mars odyssey suggests that the detection of all minerals may be enhanced by observing at an earlier time of day and thus at warmer temperatures therefore in 2009 odyssey moved to an earlier orbit time here we examine themis data collected when the earlier orbit time coincided with the martian local southern late summer ls 270 for columbus crater where compact reconnaissance imaging spectrometer for mars crism data have detected a number of aqueous minerals some of the warmest themis images show evidence for aqueous minerals although not in the same locations where crism finds the highest concentrations several factors contribute to this result including differences in the diurnal temperature curve and levels of induration and particle size for themis earlier time of day and proper seasonal observations combine to provide warm surface temperatures and ideal low atmospheric opacity that significantly increases the ability to definitively identify low spectral contrast aqueous minerals at the surface of mars

mosaicking of global planetary image datasets 2 modeling of wind streak thicknesses observed in thermal emission imaging system themis daytime and nighttime infrared data 1 large scale seamless global mosaics such as the thermal emission imaging system themis mosaics can be used to assess regional and local scale relative thermophysical properties morphology geology and other compositional investigations in this paper we use the themis global mosaics as reconnaissance tools to assess the relative thermophysical properties of materials and target a specific location to examine with a quantitative thermal model this example highlights the utility of these new data sets through an investigation of the thermophysical properties of wind streaks near the syrtis major and uranius mons regions in this study we quantitatively model depositional wind streak thicknesses near syrtis major for a thermophysically homogeneous substrate and a top layer consistent with air fall dust using this two layer thermal model we calculate that wind streaks near syrtis major are likely 30 200 m thick depending on the top layer thermal inertia given predicted dust deposition and removal rates we calculate that these wind streaks likely formed in 200 mars years and represent some of the youngest aeolian features on mars the regional wind patterns identified using the themis daytime and nighttime temperature mosaics were related to general circulation model data to constrain the season and time of day that best match the observed wind directions the themis global mosaics provide excellent context for integrating data from other instruments and provide the basis for interpreting many physical mineralogical and morphologic aspects of mars

a global view of martian surface compositions from mgs tes thermal emission spectrometer tes data from the mars global surveyor mgs are used to determine compositions and distributions of martian low albedo regions two surface spectral signatures are identified from low albedo regions comparisons with spectra of terrestrial rock samples and deconvolution results indicate that the two compositions are a basaltic composition dominated by plagioclase feldspar and clinopyroxene and an andesitic composition dominated by plagioclase feldspar and volcanic glass the distribution of the two compositions is split roughly along the planetary dichotomy the basaltic composition is confined to older surfaces and the more silicic composition is concentrated in the younger northern plains

distribution and characteristics of adirondack class basalt as observed by mini tes in gusev crater mars and its possible volcanic source abstract we identified 104 unique rock targets belonging to the olivine rich adirondack class using mini tes data rare rocks on the west spur of the columbia hills and on the plains east of the hills also belong to this class we present evidence that adirondack class basaltic lavas may have had their origin at apollinaris tholus linear modeling of adirondack class rock spectra shows only minor variations in mineralogy and the primary phases identified are consistent with olivine basalt having an average olivine composition of fo 45 we used factor analysis and target transformation to identify variability within a single class of rocks for the first time and we find that olivine abundance varies independently of a basaltic matrix a spectral component previously attributed to downwelling radiance is proposed here to be attributable to optically thin dust on rocks which has a greater effect on mini tes spectra than previously recognized but can explain the sloping continuum observed in adirondack class rock spectra as well as the apparent distortion of an olivine absorption spectral mixing is not completely linear leading to the overestimation of sulfate and olivine fractions and the underestimation of plagioclase feldspar although linear mixing appears to successfully replicate the majority of the observed signal published tes spectra of low albedo low dust cover olivine bearing materials do not exhibit the spectral telltales of non linear behavior probably because orbital spectra represent mostly mobile regolith that has not accumulated a sufficient dust cover over 3 6 km areas

quantitative compositional analysis of martian mafic regions using the mex omega reflectance data 2 petrological implications abstract the primary objectives of this paper are to determine the modal mineralogy of selected low albedo terrains of different ages ranging from noachian to amazonian exposed on the surface of mars this analysis is conducted using the spectral modeling of the observatoire pour la mineralogie l eau les glaces et l activite omega reflectance data results from this work are consistent with the major results of previous spectroscopic studies plagioclase 40 60 in volume and high calcium pyroxene 20 40 hcp are the dominant minerals of the most regions low calcium pyroxene 10 15 lcp and minor amounts of olivine are also present the oldest terrains are characterized by the largest amount of lcp and the lowest concentration of plagioclase these overall compositions are consistent with two pyroxene basalts the particle sizes are in the range of a few hundreds of micrometers which is in good agreement with the thermal inertia of the martian low albedo regions in the region around the nili fossae localized concentrations of olivine up to 40 with millimeter particle size similar to picritic basalts observed in situ by the spirit rover in the gusev crater are inferred chemical compositions are calculated for the first time from omega spectra they are quite consistent with gusev rocks and shergottite compositions but they appear to be significantly sio2 poorer than thermal emission spectrometer data a decreasing low calcium pyroxene abundance with the decreasing age of the low albedo regions is reported this may be indicative of decreasing degree of partial melting as thermal flux decreases with time we propose that the ancient noachian aged lcp rich terrains could have been formed from h2o bearing melts then dry basaltic volcanism occurred leading to decreasing lcp abundance with time due to decreasing degree of partial melting the olivine bearing material modeled in nili fossae resembles the composition of alh77005 and chassigny meteorites consistent with prior studies implications on the formation of the basaltic shergottites are discussed

evidence for komatiite type lavas on mars from phobos ism data and other observations data from the phobos 2 imaging spectrometer for mars ism compiled by mustard et al 1993 and other observations support the existence of komatiitic lavas on mars mustard et al 1993 determined from ism data that the composition of the low albedo materials covering the syrtis major plateau originally consisted of augite bearing basalt containing both augite and pigeonite with no appreciable amount of olivine this description is consistent with a komatiitic basalt komatiite is significant for the earth because it contains a high amount of mgo implying generation under unique circumstances compared to more typical basaltic compositions and may be similarly important for mars

flux of4he from carnmenellis granite modelling of an hdr geothermal reservoir abstract the diffusion coefficient d of he in the carnmenellis granite recovered from the rosemanowes hot dry rock hdr geothermal reservoir is experimentally determined in the laboratory in a temperature range of 100 300 c temperature variation of d fits an arrhenius plot but yields an activation energy for he release from rock significantly lower than the value for feldspar or quartz suggesting that most of the he in the reservoir granite resides within grain boundaries and jointing cement and may be easily released the reservoir surface area s is estimated based on the laboratory determined value of d from granite and the measured4he contents of circulation fluids from rh 15 well in the first year of reservoir circulation 4he based reservoir surface area was about twice that based on222rn it increased and stabilized at about 6 times after 2 a the excess he release from newly opened up fracture surfaces within the reservoir during its expansion is shown to be responsible for the temporal increase in the he based reservoir surface area over that of rn

coordinated spectral and xrd analyses of magnesite nontronite forsterite mixtures and implications for carbonates on mars 1 mineral detection on mars largely relies on laboratory data of minerals and mineral mixtures the objective of this study is to provide reflectance spectra in the visible near infrared vnir and mid ir regions x ray diffraction xrd data and mossbauer spectra of a suite of carbonate phyllosilicate and olivine mixtures in order to facilitate identification and characterization of these minerals on mars remote sensing observations indicate that combinations of these minerals are present in ancient rocks on mars around the isidis basin and in gusev crater magnesite nontronite and forsterite size fractions 125 m were selected for this study results of the vnir reflectance analyses illustrate the complexity of vnir spectra of mixtures analyses of the nir band depths near 2 3 2 5 3 4 and 4 m showed clear trends with carbonate abundance although the data are not linear mixtures of magnesite and nontronite exhibited a band near 2 3 m much closer to that observed for nontronite than that for magnesite vnir analyses of the mixtures indicated that a small amount of forsterite in any of the mixtures contributed a large increase in the broad 1 m band and hence the red slope characteristic of fe2 bearing minerals mid ir mixture spectra were dominated by magnesite and forsterite and nontronite was much more difficult to detect by mid ir spectra in the mixtures this could be related to why phyllosilicates are detected in many locations on mars using data collected by the compact reconnaissance imaging spectrometer for mars but not detected using data collected by the thermal emission spectrometer mossbauer spectroscopy is well suited for analyses of fe2 and fe3 bearing minerals and modeling of the peak areas gave well correlated trends for nontronite and forsterite abundances where abundant fe was present xrd full pattern fitting analyses were performed on the magnesite forsterite series giving results within 6 wt of the actual values with a mean difference between actual and calculated values of 2 4 wt this study provides important laboratory data for characterizing the spectral and xrd properties of mineral mixtures that will facilitate mineral identification on mars carbonates in particular have been primarily observed at low abundances and in small outcrops and they are frequently found mixed with other minerals through analyses of mineral mixtures using multiple data sets this study seeks to provide ground truthing that will enable better coordination of carbonate detections in the dust and rocks of mars

morphology and composition of the surface of mars mars odyssey themis results the thermal emission imaging system themis on mars odyssey has produced infrared to visible wavelength images of the martian surface that show lithologically distinct layers with variable thickness implying temporal changes in the processes or environments during or after their formation kilometer scale exposures of bedrock are observed elsewhere airfall dust completely mantles the surface over thousands of square kilometers mars has compositional variations at 100 meter scales for example an exposure of olivine rich basalt in the walls of ganges chasma thermally distinct ejecta facies occur around some craters with variations associated with crater age polar observations have identified temporal patches of water frost in the north polar cap no thermal signatures associated with endogenic heat sources have been identified

searching for the source regions of martian meteorites using mgs tes integrating martian meteorites into the global distribution of igneous materials on mars the objective of this study was to identify and map possible source regions for all 5 known martian meteorite lithologies basalt lherzolite clinopyroxenite orthopyroxenite and dunite using data from the mars global surveyor thermal emission spectrometer mgs tes we deconvolved the tes data set using laboratory spectra of 6 martian meteorites los angeles zagami alh a77005 nakhla alh 84001 and chassigny as end members along with atmospheric and surface spectra previously derived from tes data global maps 16 pixels degree of the distribution of each meteorite end member show that meteorite like compositions are not present at or above tes detectability limits over most of the planet s dust free regions however we have confidently identified local scale 100s1000s km2 concentrations of olivine and orthopyroxene bearing materials similar to alh a77005 chassigny and alh 84001 in nili fossae in and near ganges chasma in the argyre and hellas basin rims and in eos chasma nakhla like materials are identified near the detection limit throughout the eastern valles marineris region and portions of syrtis major basaltic shergottites were not detected in any spatially coherent areas at the scale of this study martian meteorite like lithologies represent only a minor portion of the dust free surface and thus are not representative of the bulk composition of the ancient crust meteorite like spectral signatures identified above tes detectability limits in more spatially restricted areas tens of km are targets of ongoing analysis

high resolution thermal inertia derived from the thermal emission imaging system themis thermal model and applications 1 thermal inertia values at 100 m per pixel are determined using nighttime temperature data from the thermal emission imaging system themis on the mars odyssey spacecraft producing the highest resolution thermal inertia data set to date themis thermal inertia values have an overall accuracy of 20 a precision of 10 15 and are consistent with both thermal emission spectrometer orbital and miniature thermal emission spectrometer surface thermal inertia values this data set enables the improved quantification of fine scale surface details observed in high resolution visible images in the tharsis region surface textures and crater rims observed in visible images have no corresponding variation in the themis thermal inertia images indicating that the dust mantle is pervasive at themis scales and is a minimum of a few centimeters and up to 1 2 m thick the thermal inertia of bed form material indicates particle diameters expected for aeolian sediments and these materials are likely currently saltating variations in the thermal inertia within interior layered deposits in hebes chasma can be distinguished and the thermal inertia is too low to be consistent with bedrock or a lava flow thus a secondary emplacement of volcanic material or a volcanic ash deposit is a more likely method of formation higher resolution themis thermal inertia enables the identification of exposed bedrock on the martian surface in nili patera and ares vallis bedrock material corresponds to distinct compositional and morphologic surfaces indicating that a specific unit is exposed and is likely currently being kept free of unconsolidated material by aeolian processes

bulk mineralogy of the ne syrtis and jezero crater regions of mars derived through thermal infrared spectral analyses abstract we investigated the area to the northwest of the isidis impact basin hereby referred to as nw isidis using thermal infrared emission datasets to characterize and quantify bulk surface mineralogy throughout this region this area is home to jezero crater and the watershed associated with its two deltaic deposits in addition to ne syrtis and the strong and diverse visible near infrared spectral signatures observed in well exposed stratigraphic sections the spectral signatures throughout this region show a diversity of primary and secondary surface mineralogies including olivine pyroxene smectite clays sulfates and carbonates while previous thermal infrared investigations have sought to characterize individual mineral groups within this region none have systematically assessed bulk surface mineralogy and related these observations to visible near infrared studies we utilize an iterative spectral unmixing method to statistically evaluate our linear thermal infrared spectral unmixing models to derive surface mineralogy all relevant primary and secondary phases identified in visible near infrared studies are included in the unmixing models and their modeled spectral contributions are discussed in detail while the stratigraphy and compositional diversity observed in visible near infrared spectra are much better exposed and more diverse than most other regions of mars our thermal infrared analyses suggest the dominance of basaltic compositions with less observed variability in the amount and diversity of alteration phases these results help to constrain the mineralogical context of these previously reported visible near infrared spectral identifications the results are also discussed in the context of future in situ investigations as the nw isidis region has long been promoted as a region of paleoenvironmental interest on mars

reproducing hydrogeochemical conditions triggering the formation of carbonate and phyllosilicate alteration mineral assemblages on mars nili fossae region 1 the cooccurrence of mg fe ca carbonate and stratigraphically lower phyllosilicate bearing rock units identified in the nili fossae region on mars may reveal a co2 driven aqueous alteration process on ancient mars we reproduce hydrogeochemical conditions for concurrent carbonate and phyllosilicate formation in rock columns by using hydrogeochemical one dimensional transport modeling which is based on chemical equilibrium thermodynamics our models assume the isochemical low temperature equilibration of ultramafic rocks with pure water at varying atmospheric co2 partial pressure water to rock ratio temperature and rock composition equilibration among 1 mineral assemblages of olivine rich rocks 18 28 wt mgo 2 pure water water to rock ratio 500 50 mol mol 1 3 co2 transferred from the atmosphere co2 partial pressure lower than 2 bars and higher than 0 01 bar at 278 k and 4 100 000 years of diffusive mass transport create hydrogeochemical conditions enabling the concurrent formation of mg rich mg fe ca solid solution carbonate and stratigraphically lower phyllosilicate rich alteration assemblages in rock columns the modeled composition of alteration mineral assemblages their depth distribution and carbonate composition are similar to the observations from the nili fossae region higher equilibration temperature 373 k results in the formation of ca dominated ca mg carbonate instead of mg rich mg fe ca carbonate and in an inverse stratification with phyllosilicate rich units overlying carbonate rich units modeling results suggest that rocks in the nili fossae region hosting the carbonate and phyllosilicate mineral assemblage have been exposed to a groundwater alteration process driven by atmospheric co2 partial pressures ranging between 2 bars and 0 01 bar at low temperature 278 k

methane bursts as a trigger for intermittent lake forming climates on post noachian mars lakes existed on mars later than 3 6 billion years ago according to sedimentary evidence for deltaic deposition the observed fluviolacustrine deposits suggest that individual lake forming climates persisted for at least several thousand years assuming dilute flow but the lake watersheds little weathered soils indicate a largely dry climate history with intermittent runoff events here we show that these observational constraints although inconsistent with many previously proposed triggers for lake forming climates are consistent with a methane burst scenario in this scenario chaotic transitions in mean obliquity drive latitudinal shifts in temperature and ice loading that destabilize methane clathrate using numerical simulations we find that outgassed methane can build up to atmospheric levels sufficient for lake forming climates if methane clathrate initially occupies more than 4 of the total volume in which it is thermodynamically stable such occupancy fractions are consistent with methane production by water rock reactions due to hydrothermal circulation on early mars we further estimate that photochemical destruction of atmospheric methane curtails the duration of individual lake forming climates to less than a million years consistent with observations we conclude that methane bursts represent a potential pathway for intermittent excursions to a warm wet climate state on early mars

mineralogy of the nili fossae region with omega mars express data 2 aqueous alteration of the crust 1 nili fossae is a region with fresh exposures of old material omega spectral data have revealed a strong diversity of minerals in the nili fossae region including mafic minerals and phyllosilicates phyllosilicates are found to be primarily fe rich smectites a type of clay minerals these phyllosilicates are observed only on the noachian crust in four types of locations three are without any signatures other than phyllosilicates on 1 smooth layered deposits 2 massive exhumed material and 3 crater ejecta and one type of location is associated with olivine 4 over an altered mafic unit this diversity suggests a widespread liquid water activity and a variety of alteration processes the formation of phyllosilicates underwent considerable reduction if not cessation by the time of formation of syrtis major lava flows in the hesperian period phyllosilicates are spatially and chronologically disconnected from the fluvial and depositional landforms observed in the nili fossae region observations suggest that these landforms formed after the extensive formation of phyllosilicates during short periods of time and or temperatures close to freezing

assessing martian bedrock mineralogy through windows in the dust using near infrared and thermal infrared remote sensing abstract much of mars surface is mantled by bright dust which masks the spectral features used to interpret the mineralogy of the underlying bedrock despite the wealth of near infrared nir and thermal infrared tir data returned from orbiting spacecraft in recent decades the detailed bedrock composition of approximately half of the martian surface remains relatively unknown due to dust cover to address this issue and to help gain a better understanding of the bedrock mineralogy in dusty regions dust cover index results from the mars global surveyor thermal emission spectrometer tes and analysis of images from the mars reconnaissance orbiter mars color imager marci were used to identify 63 small localized areas within the classical bright dusty regions of arabia terra elysium planitia and tharsis montes as potential windows through the dust that is areas where the dust cover is thin enough to permit infrared remote sensing of the underlying materials the mineralogy of each candidate window was inferred using spectra from the mars express observatoire pour la mineralogie l eau les glaces et l activite omega nir spectrometer and where possible tes twelve areas of interest returned spectra that are consistent with mineral species expected to be present at the regional scale such as high and low calcium pyroxene olivine and iron bearing glass distribution maps were created using previously defined index parameters for each species present within an area high quality tes spectra if present within an area of interest were deconvolved to estimate modal mineralogy and to support nir interpretations omega data from arabia terra and elysium planitia are largely similar and indicate the presence of high calcium pyroxene with significant contributions of glass and olivine while tes data suggest an intermediate between the established compositions of the southern highlands and syrtis major limited data from tharsis are consistent with low calcium pyroxene mixed with lesser amounts of glass and high calcium pyroxene tes data from southern tharsis correlate well with the previously inferred compositions of the aonium and mare sirenum highlands immediately to the south of particular note is the detection of iron bearing glass as a significant component of all three analyzed regions especially in tharsis overall the underlying compositions of the classically dust covered regions of mars appear consistent with the compositions of adjacent and other low albedo not dust covered regions of the planet identified in previous studies with the noted contribution from iron bearing glass

a systematic mapping procedure based on the modified gaussian model to characterize magmatic units from olivine pyroxenes mixtures application to the syrtis major volcanic shield on mars clenet et al 2011 have developed an adapted version of the modified gaussian model mgm the improvements allow the characterization of spectra of olivine pyroxene s mixtures addressing both modal composition and individual minerals chemical composition this version of mgm is fully automated and operational with large amounts of hyperspectral imaging data two natural cases are considered the first one is the sumail massif in the oman ophiolite earth based on our approach applied to hymap data two contrasted lithologic units are mapped the mantle which is harzburgite dominated and the crust made of gabbros and clinopyroxene rich cumulates with spectral variations interpreted in terms of pyroxenes chemical compositions once this new mgm mapping approach has been validated on a controlled natural situation we map the distribution of mafic assemblages across the syrtis major volcano on mars using a visible and near infrared vnir short wave infrared swir observatoire pour la mineralogie l eau les glaces et l activite omega mars express mex mosaic our results are in agreement with previous work but olivine appears to be more abundant than previously estimated in the central part of the volcanic edifice especially in ternary mafic assemblages augite olivine enstatite based on these results we propose a possible scenario for the igneous and thus thermal evolution of the syrtis major region surrounding terrains have formed first and local heterogeneity can be observed between northern and southern areas of the noachian crust we also observe variations in the mineral assemblages within syrtis major lavas which can be interpreted in terms of differentiation from a common parent melt and or of a progressive evolution of the mantle source composition and temperature key points mgm systematic mapping on syrtis major to characterize mafic minerals mixtures olivine and pyroxenes mixture is detected in the central lavas of the volcano pyroxenes have chemical compositions spanning the enstatite augite range

clay minerals in delta deposits and organic preservation potential on mars clay rich sedimentary deposits are often sites of organic matter preservation and have therefore been sought in mars exploration however regional deposits of hydrous minerals including phyllosilicates and sulphates are not typically associated with valley networks and layered sediments that provide geomorphic evidence of surface water transport on early mars the compact reconnaissance imaging spectrometer for mars crism has recently identified phyllosilicates within three lake basins with fans or deltas that indicate sustained sediment deposition eberswalde crater holden crater and jezero crater here we use high resolution data from the mars reconnaissance orbiter mro to identify clay rich fluvial lacustrine sediments within jezero crater which has a diameter of 45 km the crater is an open lake basin on mars with sedimentary deposits of hydrous minerals sourced from a smectite rich catchment in the nili fossae region we find that the two deltas and the lowest observed stratigraphic layer within the crater host iron magnesium smectite clay jezero crater holds sediments that record multiple episodes of aqueous activity on early mars we suggest that this depositional setting and the smectite mineralogy make these deltaic deposits well suited for the sequestration and preservation of organic material

improved edge detection mapping through stacking and integration a case study in the bathurst mining camp airborne geophysical surveys provide spatially continuous regional data coverage which directly reflects subsurface petrophysical differences and thus the underlying geology a modern geologic mapping exercise requires the fusion of this information to complement what is typically limited regional outcrop often interpretation of the geophysical data in a geological context is done qualitatively using total field and derivative maps with a qualitative approach the resulting map product may reflect the interpreter s bias source edge detection provides a quantitative means to map lateral physical property changes in potential and non potential field data there are a number of source edge detection algorithms all of which apply a transformation to convert local signal inflections associated with source edges into local maxima as a consequence of differences in their computation the various algorithms generate slightly different results for any given source depth geometry contrast and noise levels to enhance the viability of any detected edge it is recommended that one combines the output of several source edge detection algorithms here we introduce a simple data compilation method deemed edge stacking which improves the interpretable product of source edge detection through direct gridding grid addition and amplitude thresholding in two examples i e a synthetic example and a real world example from the bathurst mining camp new brunswick canada a number of transformation algorithms are applied to gridded geophysical data sets and the resulting source edge detection solutions combined edge stacking combines the benefits and nuances of each source edge detection algorithm coincident or overlapping and laterally continuous solutions are considered more indicative of a true edge whereas isolated points are taken as being indicative of random noise or false solutions when additional data types are available as in our example they may also be integrated to create a more complete geologic model the effectiveness of this method is limited only by the resolution of each survey data set and the necessity of lateral physical property contrasts the end product aims at creating a petrophysical contact map which when integrated with known lithological outcrop information can be led to an improved geological map

the rocks of gusev crater as viewed by the mini tes instrument 1 the miniature thermal emission spectrometer mini tes on board the mars exploration rover spirit is part of a payload designed to investigate whether a lake once existed in gusev crater mini tes has observed hundreds of rocks along the rover s traverse into the columbia hills yielding information on their distribution bulk mineralogy and the potential role of water at the site although dust in various forms produces contributions to the spectra we have established techniques for dealing with it all of the rocks encountered on the plains traverse from the lander to the base of the columbia hills share common spectral features consistent with an olivine rich basaltic rock known as adirondack class beginning at the base of the west spur of the columbia hills and across its length the rocks are spectrally distinct from the plains but can be grouped into a common type called clovis class these rocks some of which appear as in place outcrop are dominated by a component whose spectral character is consistent with unaltered basaltic glass despite evidence from other rover instruments for significant alteration the northwest flank of husband hill is covered in float rocks known as wishstone class with spectral features that can be attributed uniquely to plagioclase feldspar a phase that represents more than half of the bulk mineralogy rare exceptions are three classes of basaltic exotics found scattered across husband hill that may represent impact ejecta and or float derived from local intrusions within the hills the rare outcrops observed on husband hill display distinctive spectral characteristics the outcrop called peace shows a feature attributable to molecular bound water and the outcrop that hosts the rock called watchtower displays a dominant basaltic glass component despite evidence from the rover s payload for significant alteration of some of the rocks no unambiguous detection of crystalline phyllosilicates or other secondary silicates has been observed by mini tes the mineralogical results supplied by mini tes provide no clear evidence that a lake once existed in gusev crater

carbon sequestration on mars on earth carbon sequestration in geologic units plays an important role in the carbon cycle scrubbing co 2 from the atmosphere for long term storage while carbonate is identified in low abundances within the dust and soils of mars at 1 wt in select meteorites and in limited outcrops no massive carbonate rock reservoir on mars has been identified to date here we investigate the largest exposed carbonate bearing rock unit the nili fossae plains combining spectral thermophysical and morphological analyses to evaluate the timing and carbon sequestration potential of rocks on mars we find that the olivine enriched 20 25 basalts have been altered by low temperature in situ carbonation processes to at most 20 fe mg carbonate thus limiting carbon sequestration in the nili fossae region to 0 25 12 mbar of co 2 during the late noachian early hesperian before or concurrent with valley network formation while this is large compared to modern day co 2 reservoirs the lack of additional comparably sized post late noachian carbonate bearing deposits on mars indicates ineffective carbon sequestration in rock units over the past 3 7 b y this implies a thin atmosphere 500 mbar during valley network formation extensive post noachian atmospheric loss to space or diffuse deep sequestration by a yet to be understood process in stark contrast to earth s biologically mediated crust atmosphere carbon reservoir ratio of 10 4 10 5 mars ratio is a mere 10 10 3 even if buried pre noachian crust holds multiple bars

orbital identification of carbonate bearing rocks on mars geochemical models for mars predict carbonate formation during aqueous alteration carbonate bearing rocks had not previously been detected on mars surface but mars reconnaissance orbiter mapping reveals a regional rock layer with near infrared spectral characteristics that are consistent with the presence of magnesium carbonate in the nili fossae region the carbonate is closely associated with both phyllosilicate bearing and olivine rich rock units and probably formed during the noachian or early hesperian era from the alteration of olivine by either hydrothermal fluids or near surface water the presence of carbonate as well as accompanying clays suggests that waters were neutral to alkaline at the time of its formation and that acidic weathering proposed to be characteristic of hesperian mars did not destroy these carbonates and thus did not dominate all aqueous environments

super resolution of themis thermal infrared data compositional relationships of surface units below the 100 meter scale on mars abstract the thermal emission imaging system themis has provided the highest spatial resolution 100 m pixel thermal infrared tir data of the surface of mars to date these data have enabled the discovery of many small scale compositional units and helped to better constrain surface processes operating at these scales however with higher resolution visible vis instruments revealing smaller scale surficial differences there exists a need to detect and map compositional variability using tir data at scales below 100 m because it is unlikely there will be a higher resolution tir instrument sent to mars in the near future creative image processing techniques commonly classified under the umbrella of super resolution can be employed to improve or enhance the spatial resolution of the themis tir data these approaches typically integrate another higher resolution dataset and can either be qualitative for visual appeal quantitative for data accuracy or some combination of both the super resolution approach presented here produces enhanced tir images that are radiometrically accurate but also visually appealing for the technique to be successfully applied multi to hyper spectral data from two different spectral regions are required e g the themis tir and vis datasets the focus here is to introduce this new super resolution methodology and demonstrate its ability using existing themis ir and vis data the quartzofeldspathic deposit in northern syrtis major was selected because of the spectral variability detected using the original ir resolution data and to better constrain the relationship between the small scale surface morphology and areal extent of the deposit as well as its formation process despite being associated with the central peaks of two craters the results here show no positive correlation between the small rocky outcrops and the quartzofeldspathic unit a gradational contact exists between the unit and basaltic sands within the intercrater eolian material the super resolution approach offers an alternative approach to traditional sub pixel deconvolution identification and provides a higher resolution ir dataset for thermophysical and spectral analysis on mars

the mars global digital dune database mgd3 global patterns of mineral composition and bedform stability abstract we present an expansion to the mars global digital dune database mgd3 describing 1 bulk dune field composition determined by fitting a mineral spectral library to thermal emission spectra tes data and 2 a morphologic stability index that measures the degree of non aeolian modification that has eroded and stabilized each dune field this paper describes results for these two components providing insight into global patterns of dune sand sources postdepositional alteration and mineral maturity consistent with the work of others the main mineral components of each analyzed dune field are feldspar pyroxene and high silica phases with minor amounts of olivine and possibly sulfate minerals subtle global scale spatial variations in olivine and feldspar abundances correspond with previously observed trends in surface mineralogy suggesting that dune sand is reflective of its regional setting and thus that aeolian sand has typically not traveled far

evidence for extensive olivine rich bedrock on mars color infrared observations of an area around the nili fossae acquired by the mars odyssey thermal emission imaging system have been used to map the regional distribution and geologic context of olivine rich materials that first were identified from mars global surveyor thermal emission spectrometer data spectral thermal geomorphic and topographic data demonstrate that the majority of olivine rich material is in the form of inplace layered rock covering an area roughly four times larger than previously recognized some high olivine concentrations are associated with spatially small areas dominated by sediments we favor olivine rich basalts as the origin of the observed olivine enrichment although several hypotheses are viable

global investigation of olivine on mars insights into crust and mantle compositions 1 we present the distribution of olivine on mars derived from spectral parameters based on the 1 m olivine absorption band the olivine can be defined with respect to two spectral end members type 1 corresponds to olivine with low iron content and or small grain size and or small abundance and type 2 which corresponds to olivine with higher iron content and or larger grain size and or larger abundance the spatial and statistical analysis of the global olivine distribution points out five major geological settings where olivine is detected 1 early hesperian olivine bearing smooth crater floors and flat intercrater plains throughout the southern highlands 2 olivine deposits around the three main basins argyre hellas and isidis 3 olivine in intercrater dunes crater ejecta or extended deposits in the northern plains 4 olivine associated with outcrops and sand in the floor of valles marineris and 5 olivine bearing butte outcrops in the vicinity of hellas the geological context the age and the composition of the olivine detections associated with these five major geological settings are detailed their origin and the implication of their occurrence on the composition of the martian mantle and crust as well as on the evolution of mars volcanism are discussed

the utopia isidis overlap possible conduit for mud volcanism on mars abstract the largest areal concentration of pitted cones on mars is located in the southwest section of utopia basin this particular area of pitted cones has been attributed to mud volcanism several factors may have facilitated extensive mud volcanism at this location the concentration of pitted cones is located where utopia basin intersects isidis basin both features are multi ring impact basins on earth seismic investigations have shown that the outer rings of the chicxulub multi ring impact basin extend to the mohorovicic discontinuity moho if this is true on mars as well the fractures could act as conduits for water from utopia planitia the site of a large putative water body it has been shown that methane can be generated at the mantle on earth on mars this possible source of methane could combine with the infiltrated water to generate clathrates while methane is not currently being released at the location of the pitted cones it could have been in the past three locations of methane release have been observed on mars two of which are located on the same outer ring of isidis basin that intersects the pitted cone population the area of utopia basin that contains the large population of pitted cones is adjacent to the highland lowland boundary where extensive deposition would have occurred extensive deposition combined with the potential for methane release may have contributed to the large population of pitted cones in this area of the utopia basin

discovery of olivine in the nili fossae region of mars we have detected a 30 000 square kilometer area rich in olivine in the nili fossae region of mars nili fossae has been interpreted as a complex of grabens and fractures related to the formation of the isidis impact basin we propose that post impact faulting of this area has exposed subsurface layers rich in olivine linear mixture analysis of thermal emission spectrometer spectra shows surface exposures of 30 olivine where the composition of the olivine ranges from fo30 to fo70

using a mineral lifetime diagram to evaluate the persistence of olivine on mars we present a diagram that shows the effect of ph temperature grain size composition hydrodynamics and the laboratory field discrepancy on the lifetime of olivine grains in weathering environments because the persistence of olivine grains on mars can be used to constrain the duration of liquid water we can use this diagram to predict a range of possible maximum contact times for olivine grains with liquid water before they dissolve away completely depending upon the physicochemical conditions this contact time could range between a few thousand and several million years

analysis of phyllosilicate deposits in the nili fossae region of mars comparison of tes and omega data abstract diverse phyllosilicate deposits discovered previously in the nili fossae region with near infrared reflectance data are a window into the complex history of aqueous alteration on mars in this work we used thermal infrared data from the thermal emission spectrometer tes in combination with near infrared data from the observatoire pour la mineralogie l eau les glaces et l activite omega to better constrain the mineralogy and geologic origin of these deposits we developed a tes spectral index for identification of clay minerals which correctly identifies the phyllosilicates in the nili fossae area and points to several other interesting deposits in the syrtis major region however detailed inspection of the tes spectral features of nili fossae phyllosilicates shows a feature at low wavenumbers 350 550 cm 1 that is not an exact match to any specific fe 3 al or mg rich phyllosilicate phase instead the feature is more similar to basaltic glass and may indicate that the phyllosilicates in this region are 1 rich in fe 2 based on similarity to trends seen in laboratory data of clay minerals 2 poorly crystalline extremely disordered and or 3 present within a matrix of actual basalt glass this feature is similar to spectral features seen in altered rocks in the columbia hills region of gusev crater by previous authors by calibrating measured spectral index values against mathematical spectral mixtures of typical martian dark surfaces and known abundances of alteration minerals we are able to estimate an enrichment in abundance of alteration minerals in the altered surfaces many dark noachian deposits in the nili fossae area are enriched phyllosilicates by 20 30 10 15 relative to dark volcanic surfaces in the same region the distribution and abundance of these phases indicates that alteration in the region was pervasive but did not completely erase the original mineralogy of what was likely an fe rich basalt protolith as a group the nili fossae phyllosilicate deposits are fundamentally different from those found in the mawrth vallis region nili fossae deposits have strong thermal infrared features related to admixed pyroxene plagioclase and occasionally olivine whereas the mawrth vallis deposits contain no mafic minerals comparison of tes and omega data also illustrates some more general differences between the datasets including the impact of physical character of the martian surface on detectability of minerals in each spectral range

laboratory simulations of acid sulfate weathering under volcanic hydrothermal conditions implications for early mars we have completed laboratory experiments and thermochemical equilibrium models to investigate secondary mineral formation under conditions akin to volcanic hydrothermal acid sulfate weathering systems our research used the basaltic mineralogy at cerro negro volcano nicaragua characterized by plagioclase pyroxene olivine and volcanic glass these individual minerals and whole rock field samples were reacted in the laboratory with 1 molal sulfuric acid at varying temperatures 65 150 and 200 c fluid rock weight ratios 1 1 4 1 and 10 1 and durations 1 60 days thermochemical equilibrium models were developed using geochemist s workbench to understand the reaction products and fluids we employed scanning electron microscopy energy dispersive spectroscopy x ray diffraction and inductively coupled plasma atomic emission spectroscopy the results of our experiments and models yielded major alteration minerals that include anhydrite natroalunite minor iron oxide and amorphous al si gel we found that variations in experimental parameters did not drastically change the suite of minerals produced instead abundance size and crystallographic shape changed our results also suggest that it is essential to separate phases formed during experiments from those formed during fluid evaporation to fully understand the reaction processes our laboratory reacted and model predicted products are consistent with the mineralogy observed at places on mars however our results indicate that determination of the formation conditions requires microscopic imagery and regional context as well as a thorough understanding of contributions from both experiment precipitation and fluid evaporation minerals

composition and thermal inertia of the mawrth vallis region of mars from tes and themis data abstract clay mineral bearing deposits previously discovered on mars with near infrared 0 3 5 m remote sensing data are of major significance for understanding the aqueous history geological evolution and past habitability of mars in this study we analyzed the thermal infrared 6 35 m surface properties of the most extensive phyllosilicate deposit on mars the mawrth vallis area clay mineral bearing units which in visible images appear to be relatively light toned layered bedrock have thermal inertia values ranging from 150 to 460 j m 2 k 1 s 1 2 this suggests the deposits are composed of a mixture of rock with sand and dust at 100 meter scales dark toned materials that mantle the clay bearing surfaces have thermal inertia values ranging from 150 to 800 indicating variable degrees of rockiness or induration of this younger sedimentary or pyroclastic unit thermal emission spectrometer tes spectra of the light toned rocks were analyzed with a number of techniques but none of the results shows a large phyllosilicate component as has been detected in the same surfaces with near infrared data instead tes spectra of light toned surfaces are best modeled by a combination of plagioclase feldspar high silica materials similar to impure opaline silica or felsic glass and zeolites we propose three hypotheses for why the clay minerals are not apparent in thermal infrared data including effects due to surface roughness sub pixel mixing of multiple surface temperatures and low absolute mineral abundances combined with differences in spatial sampling between instruments zeolites modeled in tes spectra could be a previously unrecognized component of the alteration assemblage in the phyllosilicate bearing rocks of the mawrth vallis area tes spectral index mapping suggests that fe mg clays detected with near infrared data correspond to trioctahedral fe2 clay minerals rather than nontronite like clays the average mineralogy and geologic context of these complex interbedded deposits suggests they are either aqueous sedimentary rocks altered pyroclastic deposits or a combination of both

an in situ record of major environmental transitions on early mars at northeast syrtis major the noachian hesperian transition on mars was a period marked by changes in volcanic processes and styles of aqueous alteration understanding the timing and nature of environmental change requires the exploration of units recording both sets of processes herein we report the compositional stratigraphy of distinctive noachian to hesperian units along the northeastern margin of the syrtis major volcanic flows a layered polyhydrated sulfate bearing unit with jarosite ridges has been discovered beneath the syrtis major lava flows and above the regionally extensive stratigraphy of noachian plains units reported previously sequential clay carbonate and sulfate bearing units formed in situ and record a transition from alkaline ph to acidic ph waters the sequence is chronologically bookended by the isidis impact and syrtis major flows and is one of the most temporally constrained and well preserved stratigraphic sections from early mars available for landed exploration