chloride bearing materials in the southern highlands of mars chlorides commonly precipitate during the evaporation of surface water or groundwater and during volcanic outgassing spectrally distinct surface deposits consistent with chloride bearing materials have been identified and mapped using data from the 2001 mars odyssey thermal emission imaging system these deposits are found throughout regions of low albedo in the southern highlands of mars geomorphologic evidence from orbiting imagery reveals these deposits to be light toned relative to their surroundings and to be polygonally fractured the deposits are small

definitive evidence of hesperian basalt in acidalia and chryse planitiae 1 the surface materials of acidalia and chryse planitiae mars have been variably interpreted morphologically as basalt and compositionally as andesite or altered basalt a thorough survey using the compact reconnaissance imaging spectrometer for mars crism near infrared spectrometer reveals olivine and high calcium pyroxene signatures in the shallow subsurface exposed by impact craters these signatures indicate that the near surface of these regions are primarily basaltic in nature and are similar to other regions of hesperian volcanism across mars e g syrtis major previous spectroscopic studies using coarser resolution data sets have failed to identify these mafic signatures due to obscuration of the underlying material in addition to the relatively small scale exposures in impact craters the nature of the surficial obscuration material is likely multifaceted and includes the deposition of latitude dependent mantling material and the presence of alteration rinds this observation shows that the northern plains of mars are basaltic and must be factored into the thermal and surficial evolution of mars

early plate tectonics versus single plate tectonics on mars evidence from magnetic field history and crust evolution 1 the consequences of an early epoch of plate tectonics on mars followed by single plate tectonics with stagnant lid mantle convection on both crust production and magnetic field generation have been studied with parameterized mantle convection models thermal history models with parameterized mantle convection not being dynamo models can provide necessary but not sufficient conditions for dynamo action it is difficult to find early plate tectonics models that can reasonably explain crust formation as is required by geological and geophysical observations and allow an early magnetic field that is widely accepted as the cause for the observed magnetic anomalies dating of crust provinces and topography and gravity data suggest a crust production rate monotonically declining through the noachian and hesperian and a present day crust thickness of more than 50 km plate tectonics cools the mantle and core efficiently and the core may easily generate an early magnetic field given a sufficiently weak mantle rheology plate tectonics can explain a field even if the core is not initially superheated with respect to the mantle because the crust production rate is proportional to temperature however an early efficient cooling will frustrate later crust production and therefore cannot explain for example the absence of prominent magnetic anomalies in the northern crustal province and the northern volcanic plains in the early hesperian voluminous crust formation following plate tectonics is possible if plate tectonics heat transfer is inefficient but then the crust growth rate has a late peak about 2 ga b p which is not observed these models also require a substantial initial superheating of the core to allow a dynamo if one accepts the initial superheating then as we will show a simple thermal evolution model with monotonic cooling of the planet due to stagnant lid mantle convection underneath a single plate throughout the evolution can better reconcile early crust formation and magnetic field generation

composition morphology and stratigraphy of noachian crust around the isidis basin definitive exposures of pristine ancient crust on mars are rare and the finding that much of the ancient noachian terrain on mars exhibits evidence of phyllosilicate alteration adds further complexity we have analyzed high resolution data from the mars reconnaissance orbiter in the well exposed noachian crust surrounding the isidis basin we focus on data from the compact reconnaissance imaging spectrometer for mars as well as imaging data sets from high resolution imagine science experiment and context imager these data show the lowermost unit of noachian crust in this region is a complex brecciated unit of diverse compositions breccia blocks consisting of unaltered mafic rocks together with rocks showing signatures of fe mg phyllosilicates are commonly observed in regions of good exposure layered or banded phyllosilicate bearing breccia rocks are observed suggestive of pre isidis sedimentary deposits in places the phyllosilicate bearing material appears as a matrix surrounding mafic blocks and the mafic rocks show evidence of complex folded relationships possibly formed in the turbulent flow during emplacement of basin scale ejecta these materials likely include both pre isidis basement rocks as well as the brecciated products of the isidis basin forming event at 3 9 ga a banded olivine unit capped by a mafic unit covers a large topographic and geographic range from northwest of nili fossae to the southern edge of the isidis basin this olivine mafic cap combination superimposes the phyllosilicate bearing basement rocks and distinctly conforms to the underlying basement topography this may be due to draping of the topography by a fluid or tectonic deformation of a previously flatter lying morphology we interpret the draping superposed olivine mafic cap combination to be impact melt from the isidis basin forming event while some distinct post isidis alteration is evident carbonate kaolinite and serpentine the persistence of olivine from the time of isidis basin suggests that large scale aqueous alteration processes had ceased by the time this unit was emplaced

deep crustal carbonate rocks exposed by meteor impact on mars mars may have once had a co2 rich atmosphere but carbonate rocks that could provide evidence for such conditions are sparse spectral analyses of rocks exposed from deep within an impact crater reveal that carbonate deposits may be extensive on mars but are buried under layers of younger volcanic rocks

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

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

hydrated silicate minerals on mars observed by the mars reconnaissance orbiter crism instrument phyllosilicates a class of hydrous mineral first definitively identified on mars by the omega observatoire pour la mineralogie l eau les glaces et l activitie instrument preserve a record of the interaction of water with rocks on mars global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy fe mg and al smectite clays this was interpreted to indicate that phyllosilicate formation occurred during the noachian the earliest geological era of mars and that the conditions necessary for phyllosilicate formation moderate to high ph and high water activity were specific to surface environments during the earliest era of mars s history here we report results from the compact reconnaissance imaging spectrometer for mars crism of phyllosilicate rich regions we expand the diversity of phyllosilicate mineralogy with the identification of kaolinite chlorite and illite or muscovite and a new class of hydrated silicate hydrated silica we observe diverse fe mg oh phyllosilicates and find that smectites such as nontronite and saponite are the most common but chlorites are also present in some locations stratigraphic relationships in the nili fossae region show olivine rich materials overlying phyllosilicate bearing units indicating the cessation of aqueous alteration before emplacement of the olivine bearing unit hundreds of detections of fe mg phyllosilicate in rims ejecta and central peaks of craters in the southern highland noachian cratered terrain indicate excavation of altered crust from depth we also find phyllosilicate in sedimentary deposits clearly laid by water these results point to a rich diversity of noachian environments conducive to habitability

compact reconnaissance imaging spectrometer for mars observations of northern martian latitudes in summer 1 this paper brings together initial results obtained of the high northern latitudes in mars years 28 and 29 between october 2006 and october 2008 these measurements confirm many previous models and shed new light on the nature of polar surface materials particularly in intermediate albedo units of the polar layered deposits many of which are found to be ice rich we identify hydrated non ice materials present in many low albedo troughs as well as in the circumpolar erg that was previously associated with gypsum we identify icy outlier deposits that may be related to subsurface thermophysical properties and permafrost new observations of the gypsum rich dune material constrain models for its formation and distribution intrinsic properties of ice content and grain size are found to be independent of the albedo of fine layered units and may provide a novel method for stratigraphic identification and correlation

regional scale stratigraphy of surface units in tyrrhena and iapygia terrae mars insights into highland crustal evolution and alteration history 1 the compositional thermophysical and geologic characteristics of surface units in iapygia and tyrrhena terra 60 e 100 e 0 30 s provide new insights into the compositional stratigraphy of the region intercrater plains are dominated by two surface units the older unit unit 1 is deficient in olivine and more degraded and likely consists of a mixture of impact volcanic and sedimentary materials the younger unit unit 2 is enriched in olivine exhibits a resistant morphology and higher thermal inertia and likely represents volcanic infilling of plains units 1 and 2 bear a strong resemblance to those previously mapped in mare serpentis a section of highlands crust located northwest of hellas basin thus the two major intercrater plains units are even more widespread than previously thought and therefore likely constitute important components of mars highland stratigraphy many craters in the region contain high thermal inertia deposits unit 3 that are compositionally identical to unit 2 these may have formed via volcanic infilling or may represent sedimentary materials that have been eroded from crater walls and lithified less common units include olivine and or pyroxene rich massifs and crater central peaks these are primarily found within hellas basin rim units and may represent mantle materials brought toward the surface during the hellas impact putative chloride deposits are primarily associated with olivine deficient surfaces unit 1 that may be heavily degraded occurrences of unit 2 the observations raise a variety of questions related to martian crustal evolution and alteration that may have more widespread implications outside the study region

morphology stratigraphy and mineralogical composition of a layered formation covering the plateaus around valles marineris mars implications for its geological history an extensive layered formation covers the high plateaus around valles marineris mapping based on hirise ctx and hrsc images reveals these layered deposits lds crop out north of tithonium chasma south of ius chasma around west candor chasma and southwest of juventae chasma and ganges chasma the estimated area covered by lds is not vert similar42 300 km2 they consist of a series of alternating light and dark beds a 100 m in total thickness that is covered by a dark unconsolidated mantle possibly resulting from their erosion their stratigraphic relationships with the plateaus and the valles marineris chasmata indicate that the lds were deposited during the early to late hesperian and possibly later depending on the region before the end of the backwasting of the walls near juventae chasma and probably before louros valles sapping near ius chasma their large spatial coverage and their location mainly on highly elevated plateaus lead us to conclude that lds correspond to airfall dust and or volcanic ash the surface of lds is characterized by various morphological features including lobate ejecta and pedestal craters polygonal fractures valleys and sinuous ridges and a pitted surface which are all consistent with liquid water and or water ice filling the pores of lds lds were episodically eroded by fluvial processes and were possibly modified by sublimation processes considering that lds correspond to dust and or ash possibly mixed with ice particles in the past lds may be compared to dissected mantle terrains currently observed in mid to high latitudes on mars which correspond to a mantle of mixed dust and ice that is partially or totally dissected by sublimation the analysis of crism and omega hyperspectral data indicates that the basal layer of lds near ganges chasma exhibits spectra with absorption bands at not vert similar1 4 m and not vert similar1 9 m and a large deep band between not vert similar2 21 and not vert similar2 26 m that are consistent with previous spectral analysis in other regions of lds we interpret these spectral characteristics as an enrichment of lds in opaline silica or by al phyllosilicate rich layers being overlain by hydroxylated ferric sulfate rich layers these alteration minerals are consistent with the aqueous alteration of lds at low temperatures

wide distribution and glacial origin of polar gypsum on mars the north polar cap of mars is associated with different kinds of superficial sediments including the circumpolar dune field interior dune fields and sedimentary veneers scattered over the ice cap in order to resolve the mineralogical composition and the regional distribution of these sediments we processed omega and crism hyperspectral data with an original method based on spectral derivation we find that gypsum is present in all areas where undefined hydrated minerals had been previously detected including superficial sedimentary veneers covering the north polar cap interior dune fields and the whole circumpolar dune field morphological and structural analyses reveal that these gypsum crystals derive directly from the interior of the ice cap the source of superficial sedimentary veneers is the dust that was previously contained in the upper part of the ice cap the ice rich north polar layered deposits npld this gypsum bearing dust was released on south facing slopes of spiral troughs and arcuate scarps by ice ablation controlled by katabatic winds by the analysis of all associations of erosional scarps and dune fields over the north polar cap we also demonstrate that the polar dunes are composed of sand sized particles that were previously contained in the sediment rich basal unit bu corresponding to the lower part of the ice cap these particles contain gypsum and were released from the bu by regressive ablation of ice at marginal scarps that border the north polar cap and by vertical ablation of ice on olympia planum from a reconstruction of wind streamlines over and around the ice cap we infer that katabatic winds descending from the polar high and rotating around the north polar cap control the release of these gypsum bearing particles by ice ablation and the redistribution of these particles in the circumpolar dune field 2011 elsevier b v

global distribution composition and abundance of olivine on the surface of mars from thermal infrared data 1 we used spectral indexing and linear deconvolution to compare thermal infrared emission spectra of fo91 fo68 fo53 fo39 fo18 and fo1 olivine samples to mars global surveyor thermal emission spectrometer tes data over low albedo regions of mars the fo91 fo68 fo53 and fo39 spectral end members were confidently identified on mars a range of compositions wider than inferred from martian meteorites small less than hundreds of square kilometers occurrences of the fo91 spectral end member are present in the rims of the argyre and hellas impact basins and may represent martian mantle materials the fo68 spectral end member is common throughout the highlands chasmata outflow channels and nili fossae region the fo53 spectral end member occurs in eastern syrtis major the nili fossae region and smooth floored craters of the highlands although less abundant than fo68 and fo53 the distribution of the fo39 spectral end member suggests that some olivine on mars is more fe rich than olivine in martian meteorites global maps of olivine show that 1 materials containing 10 20 of olivine are common in the southern highlands of mars 2 olivine is most common near the topographic dichotomy boundary and 3 olivine becomes uncommon near the poles suggesting that it may be influenced by topography and or latitude climate olivine is found in early noachian to amazonian terrains some of which may be coeval with phyllosilicate and sulfate deposits detected by omega implying that any early noachian wet period of mars climate history may have been globally inhomogeneous or insufficient to weather the olivine that remains today

multi stage zeolite facies mineralization in the hvalfjordur area iceland the hvalfjordur area 30 km north of iceland s capital reykjavik belongs to the sequence of late tertiary to early quaternary flood basalts with minor intercalations of hyaloclastites and rhyolites the basalts are affected by progressive low temperature metamorphism caused by the burial of the lava succession and higher heat flow from nearby central volcanoes low grade zeolite facies metamorphism of basaltic lavas in the hvalfjordur area results in two distinct mineral parageneses that can be correlated to events in the burial and hydrothermal history of the lava pile stage ia represents syn eruptive near surface alteration in which celadonite and silica were precipitated along primary pores during regional burial metamorphism stage ib hydrolysis of olivine and glass led to the formation of mixed layer chlorite smectite clays the chlorite content of stage ib phyllosilicate vesicle rims increases with increasing burial depth and temperature stage ii occurred after the burial and is marked by zeolite mineralization caused by higher heat flow from the laxarvogur and hvalfjordur central volcanoes altogether 11 different zeolites were found in the hvalfjordur area analcime chabazite epistilbite heulandite laumontite levyne mesolite stilbite stellerite thomsonite and yugawaralite in total three separate depth and temperature controlled zeolite zones occur in the hvalfjordur area

observations of the south seasonal cap of mars during recession in 2004 2006 by the omega visible near infrared imaging spectrometer on board mars express 1 the omega visible near infrared imaging spectrometer on board mars express has observed the southern seasonal cap in late 2004 and 2005 and then in the summer of 2006 these observations extended from the period of maximum extension close to the southern winter solstice to the end of the recession at ls 325 the spectral range and spectral resolution of omega make it possible to monitor the extent and effective grain size of co2 ice and h2o ice on the ground the level of contamination of co2 ice and h2o ice by dust and the column density of m sized ice grains in the atmosphere the co2 seasonal cap is very clean and clear in early southern winter contamination by h2o ice spreads eastward from the hellas basin until the southern spring equinox during southern spring and summer there is a very complex evolution in terms of effective grain size of co2 ice and contamination by dust or h2o ice h2o ice does not play a significant role close to the southern summer solstice contamination of co2 ice by h2o ice is only observed close to the end of the recession as well as the few h2o ice patches already reported by bibring et al 2004a these observations have been compared to the results of a general circulation model with good qualitative agreement on the distribution of h2o ice on the surface and in the atmosphere resolving the remaining discrepancies will improve our understanding of the water cycle on mars

controls on major solutes within the drainage network of a rapidly weathering tropical watershed 1 surface water chemistry in the main stem and source points of the rio icacos basin luquillo experimental forest puerto rico was studied to investigate the factors regulating spatial variability in major solutes in a rapidly weathering landscape we sampled along the main stem as well as at small source points at high elevation where fresh bedrock is frequently exposed and at low elevation in the floodplain colluvial plain of the main stem concentrations of silicon alkalinity and the sum of base cations were lower at the source points than in the main stem and were lowest in low elevation source points calcium and sodium were the dominant cations at all sampling points after sea salt correction reflecting the weathering of plagioclase feldspar throughout the basin the partial pressure of carbon dioxide pco2 tended to be higher and hco3 concentrations were lower in the low elevation source points than at other positions in the landscape when coupled with the relatively low concentrations of si and base cations this suggests that the availability of primary reactive minerals rather than carbonic acid concentrations limits weathering in these low elevation sources mechanical denudation appears to enhance chemical weathering rates not only by refreshing reactive mineral surfaces but also by contributing carbon dioxide from the decomposition of organic rich material in landslides which occur frequently the spatial variability of major solutes appears to depend primarily on the availability of fresh primary reactive minerals carbon dioxide concentrations and hydrolysis conditions

seasonal h2o and co2 ice cycles at the mars phoenix landing site 1 prelanding crism and hirise observations 1 the condensation evolution and sublimation of seasonal water and carbon dioxide ices were characterized at the mars phoenix landing site from martian northern midsummer to midspring ls 142 ls 60 for the year prior to the phoenix landing on 25 may 2008 ice relative abundances and grain sizes were estimated using data from the compact reconnaissance imaging spectrometer for mars and high resolution imaging science experiment aboard mars reconnaissance orbiter and a nonlinear mixing model water ice first appeared at the phoenix landing site during the afternoon in late summer ls 167 as an optically thin layer on top of soil co2 ice appeared after the fall equinox by late winter ls 344 the site was covered by relatively pure co2 ice 30 cm thick with a small amount of 100 m diameter water ice and soil as spring progressed co2 ice grain sizes gradually decreased a change interpreted to result from granulation during sublimation losses the combined effect of co2 sublimation and decreasing h2o ice grain sizes allowed h2o ice to dominate spectra during the spring and significantly brightened the surface co2 ice disappeared by early spring ls 34 and h2o ice by midspring ls 59 spring defrosting was not uniform and occurred more rapidly over the centers of polygons and geomorphic units with relatively higher thermal inertia values

olivine and pyroxene diversity in the crust of mars datafromthe observatoire pour la mineralogie l9eau les glaces et l9activite omega on the mars express spacecraft identify the distinct mafic rock forming minerals olivine low calcium pyroxene lcp and high calcium pyroxene hcp on the surface of mars olivine and hcp rich regions are found in deposits that span the age range of geologic units however lcp rich regions are found only in the ancient noachian aged units which suggests that melts for these deposits were derived from a mantle depleted in aluminum and calcium extended dark regions in the northern plains exhibit no evidence of strong mafic absorptions or absorptions due to hydrated materials

global mineral distributions on mars 1 determining the mineralogy of mars is an essential part of revealing the conditions of the surface and subsurface a deconvolution method was used to remove atmospheric components and determine surface mineralogy from thermal emission spectrometer data at 1 pixel per degree ppd minerals are grouped into categories on the basis of compositional and spectral similarity and global concentration maps are produced all binned pixels are fit well with rms errors of 0 005 in emissivity higher rms errors are attributed to short wavelength particle size effects on dust covered surfaces significant concentrations 0 10 of plagioclase high ca pyroxene sheet silicates high si glass and hematite are detected and display distributions consistent with previous studies elevated concentrations of plagioclase and high ca pyroxene are consistent with basaltic surfaces and are located in low albedo highlands regions north of 45 s significant concentrations of plagioclase and sheet silicates high si glass and low concentrations of high ca pyroxenes are consistent with andesitic surfaces and are concentrated in both southern and northern high latitude low albedo regions andesitic surfaces in the southern hemisphere have a lower spectral contrast than northern surfaces an isolated surface located in solis planum is spectrally distinct but compositionally similar to other surfaces interpreted to be andesitic in composition concentrations of olivine below the detection limit correctly identify its presence in two of three locations potassium feldspar low ca pyroxene basaltic glass olivine sulfate carbonate quartz and amphibole are not detected with confidence at 1 ppd the results presented here indicate a predominance of volcanic compositions within martian dust free surfaces

results from the ism experiment the imaging spectrometer ism operating in the near infrared is the first ever flown in space for planetary observation with a spectral range of 0 76 3 14 m its main goals were to obtain information on the mineralogical composition of the surfaces of mars and phobos and on the composition spatial and temporal variations of the martian atmosphere the infrared imaging spectrometer ism acquired 40 000 spectra of mars and phobos here we present the first results on the surface mineralogy of mars and phobos and the atmospheric composition of mars

identification of spectrally similar materials using the usgs tetracorder algorithm the calcite epidote chlorite problem a scheme to discriminate and identify materials having overlapping spectral absorption features has been developed and tested based on the u s geological survey usgs tetracorder system the scheme has been applied to remotely sensed imaging spectroscopy data acquired by the airborne visible and infrared imaging spectrometer aviris instrument this approach was used to identify the minerals calcite epidote and chlorite in the upper animas river watershed colorado the study was motivated by the need to characterize the distribution of calcite in the watershed and assess its acid neutralizing potential with regard to acidic mine drainage identification of these three minerals is difficult because their diagnostic spectral features are all centered at 2 3 m and have similar shapes and widths previous studies overestimated calcite abundance as a result of these spectral overlaps the use of a reference library containing synthetic mixtures of the three minerals in varying proportions was found to simplify the task of identifying these minerals when used in conjunction with a rule based expert system some inaccuracies in the mineral distribution maps remain however due to the influence of a fourth spectral component sericite which exhibits spectral absorption features at 2 2 and 2 4 m that overlap the 2 3 m absorption features of the other three minerals whereas the endmember minerals calcite epidote chlorite and sericite can be identified by the method presented here discrepancies occur in areas where all four occur together as intimate mixtures it is expected that future work will be able to reduce these discrepancies by including reference mixtures containing sericite

imaging spectroscopy earth and planetary remote sensing with the usgs tetracorder and expert systems 1 imaging spectroscopy is a tool that can be used to spectrally identify and spatially map materials based on their specific chemical bonds spectroscopic analysis requires significantly more sophistication than has been employed in conventional broadband remote sensing analysis we describe a new system that is effective at material identification and mapping a set of algorithms within an expert system decision making framework that we call tetracorder the expertise in the system has been derived from scientific knowledge of spectral identification the expert system rules are implemented in a decision tree where multiple algorithms are applied to spectral analysis additional expert rules and algorithms can be applied based on initial results and more decisions are made until spectral analysis is complete because certain spectral features are indicative of specific chemical bonds in materials the system can accurately identify and map those materials in this paper we describe the framework of the decision making process used for spectral identification describe specific spectral feature analysis algorithms and give examples of what analyses and types of maps are possible with imaging spectroscopy data we also present the expert system rules that describe which diagnostic spectral features are used in the decision making process for a set of spectra of minerals and other common materials we demonstrate the applications of tetracorder to identify and map surface minerals to detect sources of acid rock drainage and to map vegetation species ice melting snow water and water pollution all with one set of expert system rules mineral mapping can aid in geologic mapping and fault detection and can provide a better understanding of weathering mineralization hydrothermal alteration and other geologic processes environmental site assessment such as mapping source areas of acid mine drainage has resulted in the acceleration of site cleanup saving millions of dollars and years in cleanup time imaging spectroscopy data and tetracorder analysis can be used to study both terrestrial and planetary science problems imaging spectroscopy can be used to probe planetary systems including their atmospheres oceans and land surfaces

surface and crater exposed lithologic units of the isidis basin as mapped by coanalysis of themis and tes derived data products 1 the stratigraphy and mineral heterogeneity of surface and crater exposed deposits in the southwestern portion of the isidis basin were investigated using spatial spectral visible and thermophysical data sets from both the mars global surveyor and odyssey missions four themis spectral surface units were identified progressing from the libya montes highlands to the inner lowland plains of isidis planitia lithologic determinations of these spectral units were made by linear deconvolution analysis of tes data olivine rich surface materials correlate with a well documented high thermal inertia unit based on spatial and stratigraphic relationships interpreted from both crater exposed and surface exposures the olivine rich unit was determined to have formed subsequent to the isidis basin forming event morphology occurrence and linear deconvolution of this unit suggests that it may represent noachian age to hesperian age picritic lavas that erupted as early stage lavas originating from sources such as syrtis major beneath isidis and as far as tyrrhena patera these lavas are suggested to have partially filled the basin based on crater exposed occurrences and were subsequently buried by further evolved olivine poor lavas later these lavas were exposed by erosion and subsequent impacts into the basin crater scaling suggests significant infilling of the basin by these lavas that may account for craters with very high d d ratios and the well developed positive mass anomaly associated with the basin this study also demonstrates that the remote sensing of impact craters in conjunction with surface mapping is a potent mapping tool for understanding stratigraphy and the petrogenesis of the martian crust

martian polar and circum polar sulfate bearing deposits sublimation tills derived from the north polar cap previous spectroscopic studies have shown the presence of hydrated minerals in various kinds of sedimentary accumulations covering and encircling the martian north polar cap more specifically gypsum a hydrated calcium sulfate has been detected on olympia planum a restricted part of the circum polar dune field to further constrain the geographical distribution and the process of formation and accumulation of these hydrated minerals we performed an integrated morphological structural and compositional analysis of a key area where hydrated minerals were detected and where the main polar landforms are present by the development of a spectral processing method based on spectral derivation and by the acquisition of laboratory spectra of gypsum ice mixtures we find that gypsum bearing sediment is not restricted to the olympia planum dunes but is also present in all kinds of superficial sediment covering the surface of the north polar cap and the circum polar dune field spectral signatures consistent with perchlorates are also detected on these deposits the interpretation of landforms reveals that this gypsum bearing sediment was released from the ice cap by sublimation we thus infer that gypsum crystals that are now present in the circum polar dune field derive from the interior of the north polar cap gypsum crystals that were initially trapped in the ice cap have been released by sublimation of the ice and have accumulated in the form of ablation tills at the surface of the ice cap these gypsum bearing sublimation tills are reworked by winds and are transported towards the circum polar dune field comparison with sulfates found in terrestrial glaciers suggests that gypsum crystals in the martian north polar cap have formed by weathering of dust particles either in the atmosphere prior to their deposition during the formation of the ice cap and or in the ice cap after their deposition

hydrated mineral stratigraphy of ius chasma valles marineris new high resolution spectral and morphologic imaging of deposits on walls and floor of ius chasma extend previous geomorphic mapping and permit a new interpretation of aqueous processes that occurred during the development of valles marineris we identify hydrated mineralogy based on visible near infrared vnir absorptions we map the extents of these units with crism spectral data as well as morphologies in ctx and hirise imagery three cross sections across ius chasma illustrate the interpreted mineral stratigraphy multiple episodes formed and transported hydrated minerals within ius chasma polyhydrated sulfate and kieserite are found within a closed basin at the lowest elevations in the chasma they may have been precipitates in a closed basin or diagenetically altered after deposition fluvial or aeolian processes then deposited layered fe mg smectite and hydrated silicate on the chasma floor postdating the sulfates the smectite apparently was weathered out of noachian age wallrock and transported to the depositional sites the overlying hydrated silicate is interpreted to be an acid leached phyllosilicate transformed from the underlying smectite unit or a smectite jarosite mixture the finely layered smectite and massive hydrated silicate units have an erosional unconformity between them that marks a change in surface water chemistry landslides transported large blocks of wallrock some altered to contain fe mg smectite to the chasma floor after the last episode of normal faulting and subsequent landslides opal was transported short distances into the chasma from a few m thick light toned layer near the top of the wallrock by sapping channels in louros valles alternatively the material was transported into the chasma and then altered to opal the superposition of different types of hydrated minerals and the different fluvial morphologies of the units containing them indicate sequential distinct aqueous environments characterized by alkaline then circum neutral and finally very acidic surface or groundwater chemistry

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

geology of quartz and hydrated silica bearing deposits near antoniadi crater mars 1 the only area on mars where crystalline quartz has been identified from orbit is near antoniadi crater on the northern edge of the syrtis major shield volcano however the method of quartz formation has remained unknown in this study we use high resolution satellite imagery as well as thermal and near infrared spectroscopy to construct a geologic history of these deposits and their local context we find that the quartz bearing deposits are consistently co located with hydrated silica this spatial coherence suggests that the quartz formed as a diagenetic product of amorphous silica rather than as a primary igneous mineral diagenetic quartz is a mature alteration product of hydrated amorphous silica and indicates more persistent water and or higher temperatures at this site beneath the silica bearing rocks we also find spectral evidence for smectites in the lowermost exposed noachian aged breccia a similar stratigraphic sequence smectite bearing breccias beneath deposits containing minerals suggesting a greater degree of alteration has also been found at nearby exposures at nili fossae and toro crater suggesting a widespread sequence of alteration by merging the mineral detections of thermal infrared quartz feldspar and near infrared spectroscopy hydrated silica smectite clays we are able to construct a more complete geologic history from orbit

spectral reflectance and morphologic correlations in eastern terra meridiani mars the mars express observatoire pour la mineralogie l9eau les glaces et l9activite omega hyperspectral image data covering eastern terra meridiani indicate the ubiquitous presence of molecular water in etched terrain materials that disconformably overlie heavily cratered terrains and underlie the hematite bearing plains explored by the opportunity rover identification of crystalline water in kieserite mgso4 h2o is linked to materials exposed in a valley and plateau to the north of hematite bearing plains the mineralogical similarities between the etched terrain deposits examined with omega data and the layered rocks examined by opportunity imply that the ancient aqueous environments inferred from analyses of the rover data extend over regional scales

revised crism spectral parameters and summary products based on the currently detected mineral diversity on mars the investigation of hyperspectral data from the mars reconnaissance orbiter compact reconnaissance imaging spectrometer for mars crism and the observatoire pour la mineralogie l eau les glaces et l activitie omega on mars express has revealed an increasingly diverse suite of minerals present on the martian surface a revised set of 60 spectral parameters derived from corrected spectral reflectance at key wavelengths in crism targeted observations and designed to capture the known diversity of surface mineralogy on mars is presented here as summary products some of the summary products have strong heritage to omega spectral parameter calculations this paper also presents newly derived parameters that highlight locations with more recently discovered spectral signatures type locations for the diversity of currently identified mineral spectral signatures have been compiled into a library presented in this work our analysis indicates that the revised set of summary products captures the known spectral diversity of the surface and successfully highlights and differentiates between locations with differing spectral signatures the revised spectral parameter calculations and related products provide a useful tool for scientific interpretation and for future mission landing site selection and operations

mineralogy of juventae chasma sulfates in the light toned mounds mafic minerals in the bedrock and hydrated silica and hydroxylated ferric sulfate on the plateau 1 juventae chasma contains four light toned sulfate bearing mounds denoted here as a d from west to east inside the trough mafic outcrops at the base of the mounds and in the wall rock and light toned layered deposits of opal and ferric sulfates on the plateau hyperspectral visible near infrared compact reconnaissance imaging spectrometer for mars crism spectra were used to identify monohydrated and polyhydrated sulfate phs outcrops of layered material on the bright mounds most of the monohydrated sulfate signatures closely resemble those of szomolnokite feso4 h2o characterized by a water band near 2 08 m while some areas exhibit spectral features more similar to those of kieserite mgso4 h2o with a band centered closer to 2 13 m the largest phs outcrops occur on the top of mound b and their spectral features are most consistent with ferricopiapite melanterite and starkeyite but a specific mineral cannot be uniquely identified at this time coordinated analyses of crism maps mars orbiter laser altimeter elevations and high resolution imaging science experiment images suggest that mounds a and b may have formed together and then eroded into separate mounds while mounds c and d likely formed separately mafic minerals low ca pyroxene high ca pyroxene and olivine are observed in large 2 10 km wide outcrops in the wall rock and in smaller outcrops 50 500 m across at the floor of the canyon most of the wall rock is covered by at least a thin layer of dust and does not exhibit strong features characteristic of these minerals the plateau region northwest of juventae chasma is characterized by an abundance of light toned layered deposits one region contains two spectrally unique phases exhibiting a highly stratified terraced pattern crism spectra of one unit eroded into swirling patterns with arc like ridges exhibit a narrow 2 23 m band assigned to hydroxylated ferric sulfate a thin layer of a fractured material bearing an opaline silica phase is observed at the contact between the older plateau unit and the younger hydroxylated ferric sulfate bearing light toned layered deposits hydrothermal processes may have produced an acidic environment that fostered formation of the hydrated silica and hydroxylated ferric sulfate units

evidence for extensive olivine rich basalt bedrock outcrops in ganges and eos chasmas mars 1 several localized outcrops of olivine enriched bedrock have been previously identified in the ganges and eos chasma area on the eastern end of valles marineris with the thermal emission imaging system multispectral images these outcrops form a layer in the walls of ganges chasma and appear to be the remnants of a once continuous unit which was mapped over 100 km in this study we further characterize the composition forsterite content of 0 68 olivine abundance 10 to 15 thermal inertia 600 jk 1 m 2 s 1 2 consistent with in place rocky material vertical dimension 60 to 220 m extent 1100 km laterally volume 9 9 104 km3 dip 0 013 ne and continuity of this layer utilizing thermal emission spectrometer hyperspectral thermal emission imaging system multispectral and mars orbiter laser altimeter elevation data morphologic data from high resolution imagery display a relatively unmantled rough and pitted surface associated with the olivine enriched material consistent with thermal inertia data four possibilities for the origin of the olivine enriched unit are 1 volcanism associated with tectonic rifting of the valles marineris system 2 a volcaniclastic flow deposit 3 an intrusive mafic sill or 4 a discrete episode in martian history during which flood lavas were erupted onto the surface the most likely origin is an eruptive event consisting of compositionally uniform flood lavas originating from a primitive mantle source region possibly associated with the initiation of tharsis volcanism this unit is one of the largest continuous compositional units found on mars and is strikingly similar to other olivine enriched deposits identified in previous studies where compositional morphologic and thermophysical similarities are observed these similarities may indicate that there was a period in early martian history where compositionally uniform and extensive olivine enriched flood basalts were erupted on the martian surface

testing evidence of recent hydration state change in sulfates on mars the east candor interior layered deposit ild has signatures of mono and polyhydrated sulfate in alternating layers that give insight into the processes which formed these layered deposits and on the environmental conditions acting on them since then we use orbital data to explore multiple hypotheses for how these deposits formed 1 sulfate bearing ilds experience hydration changes on seasonal to a few years timescales under current mars environmental conditions 2 the deposits experience hydration under recent mars conditions but require the wetter climate of high obliquity and 3 the kieserite could be an original or diagenetic part of a complex evaporite mineral assemblage modeled climatology shows recent mars environmental conditions might pass between multiple sulfate fields however comparison of observatoire pour la mineralogie l eau les glaces et l activite omega and compact reconnaissance imaging spectrometer crism observations of the same ild do not show changes in hydration over 2 mars years low temperatures might slow the kinetics of that transition it is likely that more clement conditions during periods of high obliquity are needed to overcome mineral metastability and hydrate kieserite bearing deposits we find the alternate model that the deposit is a cyclic evaporite sequence of mono and polyhydrated sulfates also plausible but with an unexplained dearth of fe sulfates

mineralogy and morphology of geologic units at libya montes mars ancient aqueously derived outcrops mafic flows fluvial features and impacts 1 there is ample evidence of both ancient and long lasting fluvial activity and chemical alteration in the libya montes region south of isidis basin the region hosts noachian to amazonian aged surface rocks with extensive outcrops of olivine and pyroxene bearing material libya montes also features surface outcrops and or deposits hosting fe mg smectite fe mg smectite mixed with carbonate and or other fe mg rich phyllosilicates and al smectite these units likely formed through chemical alteration connected with hydrothermal activity resulting from the formation of the isidis basin and or the pervasive fluvial activity throughout this region the morphology and stratigraphy of the aqueous and mafic minerals are described using high resolution imaging science experiment and high resolution stereo camera derived digital terrain models analyses of the compact reconnaissance imaging spectrometer for mars spectra show variations in the chemistry of the fe mg smectite from nontronite like exposures with spectral features near 2 29 and 2 4 m more consistent with fe3 2oh groups in the mineral structure and saponite like outcrops with spectral features near 2 31 and 2 38 m characteristic of mg2 3oh groups these fe mg smectite bearing materials also have bands near 1 9 m due to h2o and near 2 5 m that could be due to the smectite other phyllosilicates and carbonates all regions exhibiting carbonate features near 3 4 3 5 m also have features consistent with the presence of olivine and fe mg smectite indicating that the carbonate signatures occur in rocks likely containing a mixture of these minerals the al smectite bearing rocks have bands near 1 41 1 91 and 2 19 m that are more consistent with beidellite than other al phyllosilicates indicating a higher temperature or diagenetically processed origin for this material our interpretation of the geologic history of this region is that ancient noachian basaltic crustal materials experienced extensive aqueous alteration at the time of the isidis impact during which the montes were also formed followed by emplacement of a rough olivine rich lava or melt and finally the smooth pyroxene bearing caprock unit

diverse mineralogies in two troughs of noctis labyrinthus mars two troughs in noctis labyrinthus display a diversity of mineral assemblages rarely seen spatially collocated on mars minerals identified from mars reconnaissance orbiter data within the troughs include polyhydrated and monohydrated sulfates an al clay e g kaolinite or beidellite fe mg smectites hydrated silica and or opal and a leached clay or jarosite mixture with a doublet absorption between 2 2 and 2 3 m units both pre date and post date smaller pits and depressions within the larger troughs indicating that deposition was coeval with continued extension collapse and erosion in the late hesperian to early amazonian 2 3 ga the strata within each trough display a mineralogic diversity consistent with active aqueous processes and or changing chemical conditions over time perhaps due to hydrothermal alteration of volcanic ash influxes of groundwater from nearby tharsis volcanism fumarole activity and melting snow and or ice the superposition of younger fe mg smectites over sulfates al clays and hydrated silica and or opal in both troughs indicates that this region is unique relative to most other locations on mars where the opposite progression is observed and the fe mg smectites are noachian older than 3 6 ga in age consequently these troughs may have been habitable regions on mars at a time when drier conditions dominated the surface

identification and mapping of dikes with relatively primitive compositions in thaumasia planum on mars implications for tharsis volcanism and the opening of valles marineris 1 we have identified several exposed dikes in thaumasia planum mars using themis ctx hirise and crism data these dikes extend from tens to 100 kilometers in length with average widths of 50 m they display classic en echelon patterns while cross cutting preexisting geologic features including extensive wrinkle ridges both the dikes and associated fissure eruption products have very blocky morphologies with 38 higher thermal inertia than the surrounding regions the dikes are all enriched in mg rich olivine relative to surrounding terrain and a subset also contains elevated high calcium pyroxene both of which indicate relatively primitive magma compositions we propose that these dikes might have served as feeders for the olivine enriched flood basalts in this region and may be derived from the tharsis plume these observations provide further evidence that the opening of valles marineris was facilitated by tectonic stresses following paths of preferential weakness along preexisting structures such as fractures and faults like those indicated by these dikes

distribution and formation of chlorides and phyllosilicates in terra sirenum mars 1 the terra sirenum region of mars located in the noachian southern highlands is mineralogically diverse providing unique insight into ancient aqueous processes analyses of remote sensing data over the region indicate the presence of both fe or mg rich phyllosilicates and a spectrally unique deposit interpreted to be rich in chloride salts the stratigraphic relationships indicate that the phyllosilicates are part of the ancient highland crust and that the salts were deposited at a later time in some instances there is clear morphological evidence that salts were mobilized and deposited by near surface waters

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

distribution and variation of plagioclase compositions on mars 1 this study presents the first global compositional maps of plagioclase the most abundant mineral in the martian crust linear deconvolutions of spectra from the thermal emission spectrometer tes allowed calculation of average plagioclase compositions for dust free areas on mars 60 of the equator approximately 40 of the surface for this range of latitudes as a whole surface type 1 and 2 terrains are virtually identical with respect to their average plagioclase compositions an60 the majority of tes observations were modeled as labradorite and bytownite between an50 and an90 while fewer observations were modeled with other plagioclase compositions that did not correlate with specific geologic terrains the lack of diversity in average plagioclase compositions across multiple geologic units may represent an upper martian crust with minimal variation in plagioclase compositions alternatively aeolian fluvial and or impact activity may have redistributed heterogeneous crustal material forming a relatively homogeneous global surface layer

relation of the spectroscopic reflectance of olivine to mineral chemistry and some remote sensing implications using high resolution visible and near infrared diffuse spectral reflectance we have systematically investigated apparent wavelength shifts as a function of mineral chemistry in the fe mg olivine series from fo11 to fo91 the study also shows that trace amounts of nickel can be spectrally detected in the olivine structure we show that significant compositional information can only be extracted at relatively high resolution because the overall spectral characteristics of the olivines change only subtly as a function of the fe mg ratio significant spectral variation as a function of grain size is also demonstrated adding a further complication to the interpretation of remotely sensed data from olivine rich surfaces this laboratory study is expected to aid in the interpretation of remotely sensed data from both terrestrial and extraterrestrial bodies terrestrial applications may include the recognition of ultramafic ultrabasic and basaltic terrains which in themselves may have mineral potential among extraterrestrial applications the asteroids are obvious candidates for further examination if instrumentation can provide the necessary wavelength coverage resolution and signal to noise ratio so that spectra can be compared to those laboratory data discussed here some permutations of fe mg ni relations in olivines are discussed as they apply to the interpretation of asteroid surfaces and other extraterrestrial bodies

spectrally distinct ejecta in syrtis major mars evidence for environmental change at the hesperian amazonian boundary analysis of visible and near infrared vnir imaging spectrometer data of the syrtis major volcanic complex on mars shows spectrally distinct ejecta sde around a subset of the region s impact craters we explore the nature of this spectral difference with the intention of constraining the physical cause of the distinction and the significance of their near random spatial distribution crater counting performed by baratoux et al 2007 indicated that the craters with sde are systematically younger than craters without sde extensive crater counts of the craters with sde show that they fit a consistent hartmann 2005 isochron indicting that they represent temporally continuous population this population was dated near 2 ga consistent with the counts of baratoux et al 2007 this modeled age corresponds to just after the hesperian amazonian boundary indicating that it may be related to a global event we explore possible explanations for the lack of sde around older craters including atmospheric changes significant but brief regional emplacement of materials and volcanic activity we conclude that the preferred explanation is that the sde represent the true composition of the syrtis major volcanics and that surfaces older than 2 ga were altered by interactions with water vapor or volcanic gases under different hesperian climatic and atmospheric conditions leading to all craters formed after this alteration event to display sde

martian surface mineralogy from observatoire pour la mineralogie l eau les glaces et l activite on board the mars express spacecraft omega mex global mineral maps 1 after 2 years of operation the observatoire pour la mineralogie l eau les glaces et l activite omega imaging spectrometer on board mars express has acquired data coverage of the martian surface with spatial resolution varying between 300 m and 4 8 km depending on the pericenter altitude of the spacecraft s elliptical orbit we report the global surface distributions of some minerals using the omega observations in the visible and near infrared vnir wavelength domains 0 35 2 5 m global maps of ferric phases mafic minerals pyroxenes and olivines and hydrated minerals have been derived from spectral parameters the limits of detection in terms of abundance for some minerals of different grain size distributions are given the distribution of pyroxenes is in general agreement with the mineral maps of previous telescopic and space observations the fe3 absorption feature in the visible wavelength region is present everywhere on the surface the spectra of the bright regions compare with anhydrous nanophase ferric oxides terrains with water bearing minerals cover a very small fraction of the martian surface olivine mg rich compositions is detected in more extensive regions of the pyroxene rich zones than previously reported olivine with higher iron content and or larger grain size 100 m is only detected in isolated areas the mineralogy of the northern low albedo regions is discussed in the light of these mineral maps chemical alteration or oxidation during extrusion producing a coating or varnish of anhydrous ferric phases over a dark basaltic surface best accounts for the vnir spectral properties of these regions although a glassy composition resulting from impact is also considered

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

extensive surface pedogenic alteration of the martian noachian crust suggested by plateau phyllosilicates around valles marineris 1 thousands of phyllosilicate rich outcrops mainly iron or magnesium rich are exposed on noachian terrains in the martian southern highlands we analyzed 90 crism observations and more than a hundred hirise images located on the plateaus surrounding valles marineris we mapped an extensive al and fe mg phyllosilicate rich formation covering at least 197 000 km2 for which we introduce the name plateau phyllosilicates tens of meters in thickness this light toned formation crops out at various elevations on top of the noachian units npl1 and npl2 as flat exposures on plateaus and along scarps such as valley walls chasma walls pit walls and impact crater rims the fe mg phyllosilicate rich lower member of the formation is composed of fe mg smectites nontronite saponite and vermiculite the al phyllosilicate rich upper member of the formation contains al smectites montmorillonite beidellite and locally kaolinite and or halloysite we suggest that the plateau phyllosilicates were mainly formed by pedogenesis related to the weathering of the noachian bedrock by percolation of meteoric water or melted snow under a temperate and subarid climate during the noachian epoch in an alkaline to neutral environment kaolinite and or halloysite may have formed in areas of more intense drainage at the surface under slightly acidic environments during the noachian and hesperian epochs fluvial activity and deuteric alteration may have locally contributed to the genesis of phyllosilicates this study suggests that the alteration of the noachian basement of the plateaus surrounding valles marineris was widespread during the noachian epoch and was still active during the hesperian epoch even though the water availability was limited

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

hydrous minerals on mars as seen by the crism and omega imaging spectrometers updated global view 1 the surface of mars has preserved the record of early environments in which its basaltic crust was altered by liquid water these aqueous environments have survived in the form of hydrological morphologies and alteration minerals including clays and hydrated salts because these minerals probe on earth aqueous environments compatible with biotic activity understanding their formation processes on mars is of great exobiological relevance and also offers insight into earth s now erased ancient water environments using remote sensing we conducted a large scale investigation of the distribution composition age and geomorphic settings of hydrous minerals on mars providing a sharpened global view of the early aqueous environments and their evolution with time aqueous alteration seems to have produced clays on a planetary scale but these are found to be restricted to the oldest observable terrains on mars 4 gyr however very diverse aqueous environments have also been found which suggest widespread complex aqueous settings from the surface to kilometric depths and spanning over 1 gyr by building a robust statistical sample of detections the global trends inferred here attempt to provide a broad view of our current understanding of hydrous minerals on mars and provide context for more localized in depth analyses collectively these trends suggest that at least transient conditions have existed on mars which may have been favorable for pre biotic to biotic activity

diverse aqueous environments on ancient mars revealed in the southern highlands high resolution spectral images reveal many new exposures of hydrated minerals across the noachian southern highlands of mars several different phyllosilicates are observed with inferred accompanying phases ranging from zeolites to sulfates to chlorides each in distinct geologic settings hydrated sulfates are observed in several locations at mid latitudes and likely formed independently from the equatorial sulfates these assemblages suggest a greater diversity of aqueous environments on ancient mars than has previously been recognized and their distribution implies that alteration was widespread during the noachian period not restricted to a few locations

implications for early hydrothermal environments on mars through the spectral evidence for carbonation and chloritization reactions in the nili fossae region 1 previous identification of serpentine and magnesium carbonate in the eastern nili fossae region of mars indicates hydrothermal alteration of an olivine rich protolith here we characterize fe mg phyllosilicates associated with these units and present spectral evidence for the presence of a talc component distinguishable from saponite locations with magnesium carbonate are exclusively associated with talc related phyllosilicates in the westernmost portions of the nili fossae region where a mafic protolith dominates fe mg phyllosilicates display spectral evidence for a wide degree of chloritization we propose that noachian fe mg smectites were uniformly buried by hesperian lava flows that initiated hydrothermal alteration in the eastern nili fossae region the chloritization of smectites may have produced silica rich fluids necessary for the serpentinization of olivine temperature and depth constraints indicated by their distribution also suggest a hydrothermal system was present the subsequent carbonation of serpentine and or olivine in eastern nili fossae while requiring an additional co2 source provides an explanation for the limited occurrence of serpentine and the colocation of carbonate and talc bearing material throughout this area the consequence of the hypothesized carbonation reaction and the presence of serpentine provides geochemical constraints for the proportion of co2 present in the fluids that interacted with the protolith if this carbonation reaction was a widespread phenomenon it may have been an important process in the ancient martian carbon cycle and could have provided a sink for co2 in the past

dikes of distinct composition intruded into noachian aged crust exposed in the walls of valles marineris 1 valles marineris represents the deepest natural incision in the martian upper crust previous studies showed that the upper parts of the walls were made of finely layered probable basalts in most of the chasmata while the base of the stratigraphy reveals primary noachian crustal blocks exposures of pristine noachian bedrock are rare on mars and mostly observed outside of their geological context the occurrence of well preserved and extended outcrops of pristine material in this giant rift could bring valuable information on the early processes that took place at the surface of mars analyses of high resolution data over the best exposures of lower walls in coprates chasma central valles marineris revealed the presence of multiple magmatic intrusions interpreted as dikes these dikes intrude an old massive fractured bedrock interpreted as being preserved ancient noachian crust their composition determined using crism data and distribution limited to this ancient crust at the bottom walls indicate that they might have formed early in the rift formation and therefore represent exceptionally well preserved outcrops of the early history of mars

a chemical model for evaporites on early mars possible sedimentary tracers of the early climate and implications for exploration martian geomorphology seems to indicate extensive hydrological activity during the noachian era liquid water at the surface would require a large greenhouse effect that is widely hypothesized to have been caused by a high partial pressure of atmospheric carbon dioxide pco2 a sedimentation model driven by sequential evaporation is used to calculate the evaporite mineral sequence in a closed basin lake subject to high pco2 the initial fluid is derived from weathered igneous rock similar to martian meteorite basalts siderite feco3 is always the first major carbonate to precipitate thus siderite is predicted to be an important fades component in ancient martian sediments along with silica which is also an early precipitate these would form varves in lakes that undergo cycles of evaporation and water recharge after silica and siderite the sequence is magnesian calcite nearly pure hydromagnesite and gypsum followed by highly soluble salts like nacl the presence of siderite sediments generally requires an atmospheric pco2 level in excess of 0 1 bar otherwise iron silicates such as greenalite would form this may be used in exploration as an observational test on the past atmospheric composition of mars subject to consideration of the depositional environment at pco2 of approximately several bar gypsum precipitation could occur before calcite upon evaporation if the initial so42 ca2 ratio is high and there is no water recharge the predicted carbonate sequence upon evaporation is generally consistent with recent hypotheses suggesting traces of evaporite carbonates in some martian meteorites several mechanisms destroy or obscure carbonates at the martian surface consequently in situ analysis of the interior of ejecta from recent impact craters lying within sedimentary basins may offer the most practical approach to future exploration of ancient carbonate sediments

sulfates in the north polar region of mars detected by omega mars express the observatoire pour la mineralogie l eau les glaces et l activite omega imaging spectrometer observed the northern circumpolar regions of mars at a resolution of a few kilometers an extended region at 240 e 85 n with an area of 60 kilometers by 200 kilometers exhibits absorptions at wavelengths of 1 45 1 75 1 94 2 22 2 26 and 2 48 micrometers these signatures can be unambiguously attributed to calcium rich sulfates most likely gypsum this region corresponds to the dark longitudinal dunes of olympia planitia these observations reveal that water alteration played a major role in the formation of the constituting minerals of northern circumpolar terrains

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

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

mineralogy composition and alteration of mars pathfinder rocks and soils evidence from multispectral elemental and magnetic data on terrestrial analogue snc meteorite and pathfinder samples major element multispectral and magnetic properties data were obtained at ares vallis during the mars pathfinder mission to understand the compositional mineralogical and process implications of these data we obtained major element mineralogical and magnetic data for well crystalline and nanophase ferric minerals terrestrial analogue samples with known geologic context and snc meteorites analogue samples include unaltered palagonitic and sulfatetic tephra from mauna kea volcano hydrolytic and acid sulfate alteration steam vent material from kilauea volcano hydrolytic alteration and impactites from meteor crater relithification salient results for mars pathfinder include 1 band depths bd530b and bd600 and the reflectivity ratio r800 r750 are consistent with the dominant ferric mineral being nanophase ferric oxide associated with an unknown amount of h2o and occurring in composite particles along with subordinate amounts of other ferric minerals hematite and hematite plus nanophase goethite are most consistent with the data but maghemite akaganeite schwertmannite and nanophase lepidocrocite are also possible interpretations ferric oxides that are consistently not favored by the data as sole alteration products are jarosites and well crystalline goethite and lepidocrocite 2 the strength of the ferric adsorption edge r750 r445 implies the fe3 fe2 values for pathfinder rock and soil are within the ranges 0 7 3 and 3 20 respectively 3 ferrous silicates are indicated for subsets of pathfinder rocks and soils one subset has a band minimum near 930 nm that can attributed to low ca pyroxene alternatively the band could be a second manifestation of certain ferric oxides including nanophase goethite maghemite akaganeite and schwertmannite another subset has a negative spectral slope from 800 to 1005 nm which could result from the high energy wing of a high ca pyroxene and or olivine band a mixture of bright and dark materials and for rocks thin coatings of bright dust on dark rocks 4 chemical data on pathfinder rocks and soils are consistent with two component mixtures between an andesitic rock with low mgo and so3 concentrations soil free rock and a global basaltic soil with high mgo and so3 concentrations rock free soil pathfinder rock free soil can be modeled as a chemical mixture of snc meteorites and the pathfinder soil free rock 5 pathfinder soil cannot be obtained by chemical alteration of pathfinder rocks by any of the hydrolytic and acid sulfate alteration processes we studied presumably global mixing has obscured and possibly erased the elemental signatures of chemical alteration 6 the strongly magnetic phase in palagonitic and sulfatetic tephra is titanomagnetite and possibly its oxidation product titanomaghemite fe ti spinels the saturation magnetization of the tephra samples 0 5 2 0 am2 kg is at or below the low end of the range inferred for martian dust 4 2 am2 kg implying that lithogenic fe ti spinels are a possible candidate for the martian strongly magnetic phase 7 the predominantly palagonitic spectral signature and magnetic nature of martian soil and dust are consistent with glassy precursors with imbedded fe ti spinel particles comparison with lunar glass production rates suggests that production of sufficient quantities of glassy materials on mars by volcanic and impact processes is sufficient to account for these observations

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

ancient plutonic processes on mars inferred from the detection of possible anorthositic terrains the formation of the silicate mineral anorthosite is thought to require magmatic processes that are not expected on mars because of its predominately mafic terrains localized spectral detections by the mars reconnaissance orbiter are consistent with anorthosite suggestive of ancient intrusive igneous processes similar to those active on earth

emplacement ages of kimberlite occurrences in the prieska region southwest border of the kaapvaal craton south africa abstract rb sr mica and u pb perovskite emplacement ages for kimberlites from the southwest part of the kaapvaal craton near prieska south africa vary from as old as 170 ma to as young as 74 ma similar to ages elsewhere in southern africa isotopically defined group i and ii kimberlites are found on the kaapvaal craton northeast of the doornberg and brakbos lineaments domains i and ii as defined by skinner et al 1992 with ages of 74 108 and 118 125 ma kimberlites in the craton margin area bounded by the two lineaments domain iii are exclusively group ii with ages of 116 119 ma kimberlites in domain iv to the south of the craton boundary are of group i affinity emplaced in two episodes at 74 and 100 103 ma southernmost domain v is dominated by kimberlites petrographically chemically and isotopically transitional between group i and ii types but with the oldest ages at 140 and possibly 170 ma phlogopite from a peridotite xenolith from the sanddrift kimberlite has retained an age of 2250 ma presumably the enrichment age of the nodule