the stubenberg meteorite an ll6 chondrite fragmental breccia recovered soon after precise prediction of the strewn field on march 6 2016 at 21 36 51 ut extended areas of upper austria bavaria germany and the southwestern part of the czech republic were illuminated by a very bright bolide this bolide was recorded by instruments in the czech part of the european fireball network and it enabled complex and precise description of this event including prediction of the impact area so far six meteorites totaling 1473 g have been found in the predicted area the first pieces were recovered on march 12 2016 on a field close to the village of stubenberg bavaria stubenberg is a weakly shocked s3 fragmental breccia consisting of abundant highly recrystallized rock fragments embedded in a clastic matrix the texture the large grain size of plagioclase and the homogeneous compositions of olivine fa31 4 and pyroxene fs25 4 clearly indicate that stubenberg is an ll6 chondrite breccia this is consistent with the data on o ti and cr isotopes stubenberg does not contain solar wind implanted noble gases data on the bulk chemistry ir spectroscopy cosmogenic nuclides and organic components also indicate similarities to other metamorphosed ll chondrites noble gas studies reveal that the meteorite has a cosmic ray exposure cre age of 36 3 ma and that most of the cosmogenic gases were produced in a meteoroid with a radius of at least 35 cm this is larger than the size of the meteoroid which entered the earth s atmosphere which is constrained to 20 cm from short lived radionuclide data in combination this might suggest a complex exposure history for stubenberg

seeking phyllosilicates in thermal infrared data a laboratory and martian data case study 1 previous analyses of thermal emission spectrometer tes data produce results that could suggest a widespread distribution of phyllosilicate minerals over the surface of mars whereas studies of visible to near infrared vnir data indicate a more limited distribution we use vnir detections of phyllosilicates in the vicinity of the nili fossae to determine the spectral characteristics of phyllosilicate bearing material in the thermal infrared tir by investigating areas of vnir phyllosilicate detection in more detail we find that the phyllosilicate bearing material corresponds to spectral variation in thermal emission imaging system decorrelation stretched tir images and differences in infrared spectral shape that are consistent with but not uniquely attributable to mixtures of phyllosilicates and basalt phyllosilicate phases are modeled from tes data at abundances that average 5 over the region and at abundances near the 10 15 detection limit in our specific regions of interest deconvolution of numerical mixtures of phyllosilicate and basalt spectra indicates that these low abundances of phyllosilicates likely are not influenced by uncertainties greater than the 10 15 uncertainty of the method tes spectra and modeled abundances vary between the phyllosilicate bearing material and the surrounding region but this difference in composition cannot be attributed solely to the presence of phyllosilicates we believe the inconsistencies in phyllosilicate occurrence between tes and vnir analyses may be explained by the inclusion of phyllosilicates in the models of tes data as substitutes for poorly crystalline phases e g allophane not currently available in public infrared spectral libraries

the effect of ph and temperature on the isotopic fractionation of boron between saline brine and sediments the effects of ph and temperature on the adsorption distribution of boron in sediment and the boron isotopic fractionation factor between saline brine and sediment were studied the results show that the adsorption and isotopic fractionation of boron between saline brine and sediment are similar to that between seawater and marine or pure sediments in a certain ph range the adsorption distribution factor kd and isotopic fractionation factor of boron are controlled by the ph of the saline brine kd increases with ph while decreases an unusual aspect of this study was that 11b enrichment in the solid was seen during boron adsorption by clay at high ph these results have been used to study the distribution of boron isotopes in salt lakes of qaidam basin

low temperature aqueous alteration of basalt mineral assemblages of deccan basalts and implications for mars spectra of basalt samples were dominated by fe 2 crystal field transitions with weak alteration bands near 1 4 and or 1 9 mm reststrahlen bands in mid infrared showed the convolution of plagioclase and pyroxene features typical of basalts saprolite samples were incompletely leached and their spectra were dominated by complex al and fe mg bearing smectite clays and retained no original mafic signatures xrd and mossbauer detected pyroxene and plagioclase not visible by reflectance spectroscopy in some saprolite samples zeolites were present throughout the saprolite the laterite was the most leached horizon and all analyses showed kaolinite and iron oxide assemblages this kaolinite and hematite association would be expected if kaolinite on mars formed through leaching under conditions similar to those on earth and has implications for abundant freshwater on the martian surface

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

indian continental subduction and slab break off during tertiary collision high wavespeed seismic anomalies in the transition zone and uppermost lower mantle beneath the india asia collision zone imaged by body wave seismic tomography have been interpreted as subducted fragments of continental material in this study we focus on the prominent anomaly located beneath india between depths of about 450 and 900 km by combining the location of this anomaly with palaeogeographical positions of india we constrain the timing of the subduction event probably related to this anomaly we infer that a large portion of the north western margin of india initiated subduction at 35 5 ma along a 1500 km long wnw ese striking zone and ended with a progressive slab break off process this break off started most probably around 25 ma at the western end of the slab and propagated eastwards until complete break off around 15 ma this study helps to constrain better the amount of convergence between india and asia absorbed by continental subduction

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

a model for formation of dust soil and rock coatings on mars physical and chemical processes on the martian surface 1 a model is presented here to explain the generation of surface material on mars using chemical magnetic and spectroscopic data from mars and geologic analogs from terrestrial sites one basic premise is that the dust soil units are not derived exclusively from local rocks but are rather a product of global and possibly remote weathering processes another assumption in this model is that there are both physical and chemical interactions of the atmosphere with dust particles and that these two processes create distinctly different products physical processes distribute dust particles on rocks and drift units forming physically aggregated layers these are reversible processes chemical reactions of the dust soil particles create alteration rinds on rock surfaces and cohesive crusted surface units between rocks both of which are relatively permanent materials according to this model the dominant components of the dust soil particles are derived from alteration of volcanic ash and tephra and contain primarily nanophase and poorly crystalline ferric oxide oxyhydroxide phases as well as silicates these phases are the alteration products that formed in a low moisture environment these dust soil particles also contain a smaller amount of material that was exposed to more water and contains crystalline ferric oxides oxyhydroxides sulfates and clay silicates these components could have formed through hydrothermal alteration at steam vents or fumeroles thermal fluids or through evaporite deposits wet dry cycling experiments are presented here on mars soil analogue mixtures containing poorly crystalline and crystalline components dominated by nanophase to 2 m diameter particles cemented products of these soil mixtures are formed in these experiments and variation in the surface texture was observed for samples containing smectites nonhydrated silicates or sulfates reflectance spectra were measured of the initial particulate mixtures the cemented products and ground versions of the cemented material the spectral contrast in the visible near infrared and midinfrared regions is significantly reduced for the cemented material compared to the initial soil and somewhat reduced for the ground cemented soil compared to the initial soil the results of this study suggest that transient fluvial activity on mars will have a profound effect on the texture and spectral properties of the dust soil particles on the surface the model developed in this study provides an explanation for the generation of cemented or crusted soil units and rock coatings on mars and may explain albedo variations on the surface observed near large rocks or crater rims

pyroxene spectroscopy revisited spectral compositional correlations and relationship to geothermometry the authors wish to thank the various agencies which have provided the necessary support for this project including grants in aid of research from sigma xi the scientific research society to e a c the geological society of america grant 3741 87 to e a c and nasa planetary geology and geophysics grant nagw 642 to m j g

mineralogical and spectroscopic investigation of enstatite chondrites by x ray diffraction and infrared reflectance spectroscopy 1 the mineralogy and infrared reflectance spectra of 13 enstatite e chondrite meteorite finds spanning the full range of textural alteration grades in both el and eh classes have been investigated rietveld refinement of high resolution powder x ray diffraction xrd data was used to determine quantitative major mineral abundances sample correlated mid infrared 2 0 to 25 0 m 4500 cm 1 to 400 cm 1 reflectance infrared spectra were collected for each meteorite spectral features due to the fundamental lattice vibrations of the silicates primarily enstatite dominate the spectra of these meteorites over most of the spectral range investigated the spectral features related to primary i e pre terrestrial mineralogy include fundamental stretching and bending lattice modes 8 3 25 0 m 1200 400 cm 1 overtones and combinations of the fundamental modes 4 5 6 1 m 2200 1650 cm 1 and the principle christensen feature 8 3 m 1200 cm 1 terrestrial weathering products including fe oxyhydroxides gypsum and carbonates occur in most of these meteorites and contribute to some spectral features particularly an asymmetric feature near 2 6 to 3 8 m 3800 to 2600 cm 1 attributed to adsorbed hydrogen bonded and or structural oh and h 2 o and a feature near 6 2 m 1625 cm 1 attributed to adsorbed hydrogen bonded and or structural h 2 o modal mineral abundances determined by rietveld refinement have been used to calculate model grain densities for each meteorite bulk magnetic susceptibility measurements combined with modal mineralogy and grain densities reveal a trend toward lower grain density and lower bulk susceptibility with increased terrestrial weathering

near and mid infrared microspectroscopy of the ronda peridotite 1 microspectroscopy is a potentially useful tool for planetary applications as individual mineral grains can be targeted and measured in situ a series of closely coupled experiments was designed to investigate and compare the laboratory measurement of optical properties of a peridotite sample in the macroscale and microscale the ronda peridotite consists largely of olivine with significant orthopyroxene and minor clinoproxene and serpentine microscopic transmission spectra of unmounted thin sections produce strong well defined absorption features in the near infrared and band positions can be directly compared to macroscopic and microscopic reflectance spectra for near infrared reflectance where photons are multiply scattered by different grains measurement of a microscopic target means most photons are scattered out of the field of view and few photons return to the detector from the target area this precludes most microspectroscopic reflectance measurements of small features in the near infrared in the mid infrared where reflectance measurements involve only surface interactions microspectroscopic measurements detect well defined absorption features for most samples although the intensity of absorption features varies between grains band positions are consistent with macroscopic diffuse reflectance and emittance measurements of bulk samples and can be used to extract general chemical information such as iron magnesium ratios of olivines

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

dust coatings on basaltic rocks and implications for thermal infrared spectroscopy of mars 1 thin coatings of atmospherically deposited dust can mask the spectral characteristics of underlying surfaces on mars from the visible to thermal infrared wavelengths making identification of substrate and coating mineralogy difficult from lander and orbiter spectrometer data to study the spectral effects of dust coatings we acquired thermal emission and hemispherical reflectance spectra 5 25 m 2000 400 cm 1 of basaltic andesite coated with different thicknesses of air fall deposited palagonitic soils fine grained ceramic clay powders and terrestrial loess the results show that thin coatings 10 20 m reduce the spectral contrast of the rock substrate substantially consistent with previous work this contrast reduction continues linearly with increasing coating thickness until a saturation thickness is reached after which little further change is observed the saturation thickness of the spectrally flat palagonite coatings is 100 120 m whereas that for coatings with higher spectral contrast is only 50 75 m spectral differences among coated and uncoated samples correlate with measured coating thicknesses in a quadratic manner whereas correlations with estimated surface area coverage are better fit by linear functions linear mixture modeling of coated samples using the rock substrate and coating materials as end members is also consistent with their measured coating thicknesses and areal coverage a comparison of ratios of thermal emission spectrometer tes spectra of dark and bright intracrater and windstreak deposits associated with radau crater suggests that the dark windstreak material may be coated with as much as 90 areal coverage of palagonitic dust the data presented here also will help improve interpretations of upcoming mini tes and thermal emission imaging system themis observations of coated mars surface materials

thermal infrared spectroscopy of experimentally shocked anorthosite and pyroxenite implications for remote sensing of mars 1 the feldspar and pyroxene mineralogies on mars revealed by the thermal emission spectrometer tes on mars global surveyor likely record a variety of shock effects as suggested by petrologic analyses of the martian meteorites and the abundance of impact craters on the planet s surface to study the effects of shock pressures on thermal infrared spectra of these minerals we performed shock recovery experiments on orthopyroxenite and anorthosite samples from the stillwater complex montana over peak pressures from 17 to 63 gpa we acquired emissivity and hemispherical reflectance spectra 350 1400 cm 1 7 29 mm of both coherent chips and fine grained powders of shocked and unshocked samples these spectra are more directly comparable to remotely sensed data of mars e g tes than previously acquired absorption or transmission spectra of shocked minerals the spectra of experimentally shocked feldspar show systematic changes with increasing pressure due to depolymerization of the silica tetrahedra for the spectra of chips this includes the disappearance of small bands in the 500 650 cm 1 region and a strong band at 1115 cm 1 and changes in positions of a strong band near 940 cm 1 and the christiansen feature near 1250 cm 1 spectra of the shocked powders show the gradual disappearance of a transparency feature near 830 cm 1 fewer changes are observed in the pyroxene spectra at pressures as high as 63 gpa spectra of experimentally shocked minerals will help identify more precisely the mineralogy of rocks and soils not only from tes but also from future mars instruments such as minites and themis index terms 3944 mineral physics shock wave experiments 3934 mineral physics optical infrared and raman spectroscopy 5420 planetology solid surface planets impact phenomena includes cratering 5460 planetology solid surface planets physical properties of materials keywords anorthosite pyroxenite shock spectra thermal infrared remote sensing mars

thermal infrared emissivity of felsic rich to mafic rich analogues of hot planetary regoliths abstract inner solar system bodies with absent or extremely tenuous atmospheres such as mercury and several high eccentricity near earth objects neos are subject to a wide range of surface temperatures here we show how the thermal expansion induced by strong diurnal insolation variations affects the thermal infrared spectra of felsic rich to mafic rich regoliths 1400 700 cm 1 spectra of granular plagioclase pyroxene mixtures were measured in the laboratory at four temperatures between 425 k and 725 k simulating different daily surface temperatures within the solar system at the same time we describe for the first time how two minerals with different thermal expansion coefficients combined in the same granular sample appear in a non ambient i e non 298 k thermal infrared spectrum the spectra of plagioclase rich analogues appear to be dominated by felsic features regardless of the daily surface temperature and do not exhibit any of the short wavelength absorptions of pyroxenes when detectable on the other hand the 870 cm 1 pyroxene absorption which is not affected by thermal variations functions instead as a proxy for the solid solution composition i e the mg fe relative contents in contrast indications of the plagioclase solid solution occurring at ambient temperatures i e ca na relative contents disappear at temperatures over 525 k christiansen feature position and spectral contrast which show a clear dependency on composition even at high temperatures require an accurate reproduction of the shallow thermal gradient in order to be used as indices in general in order to decipher planetary hyperspectral data surface temperature acquisition seems to be a prerequisite as well as a comparison with analogue spectra obtained under realistic environmental conditions

two stages of granulite facies metamorphism in the eastern himalayan syntaxis south tibet petrology zircon geochronology and implications for the subduction of neo tethys and the indian continent beneath asia the eastern himalayan syntaxis in southeastern tibet consists of the lhasa terrane high himalayan rocks and indus tsangpo suture zone the lhasa terrane constitutes the hangingwall of a subduction zone whereas the high himalayan rocks represent the subducted indian continent our petrological and geochronological data reveal that the lhasa terrane has undergone two stages of medium p metamorphism an early granulite facies event at c 90 ma and a late amphibolite facies event at 36 33 ma however the high himalayan rocks experienced only a single high p granulite facies metamorphic event at 37 32 ma it is inferred that the late cretaceous c 90 ma medium p metamorphism of the southern lhasa terrane resulted from a northward subduction of the neo tethyan ocean and that the oligocene 37 32 ma high p 1 8 1 4 gpa rocks of the high himalayan and coeval medium p 0 8 1 1 gpa rocks of the lhasa terrane represent paired metamorphic belts that resulted from the northward subduction of the indian continent beneath asia our results provide robust constraints on the mesozoic and cenozoic tectonic evolution of south tibet

space weathering by simulated micrometeorite bombardment on natural olivine and pyroxene a coordinated ir and tem study abstract we studied space weathering effects caused by micrometeorite bombardment simulated by pulsed intense infrared laser generating 15 mj per pulse in high vacuum for our investigation we selected a natural olivine san carlos olivine fo91 and a natural pyroxene bamble orthopyroxene en87 as important rock forming minerals of the earth upper mantle as well as key planetary minerals irradiated areas of powdered pressed samples were examined by optical reflection spectroscopy in a broad optical and infrared wavelength range visible near and mid infrared and transmission electron microscopy to identify changes due to micrometeorite impacts the present study aims to investigate especially the effects of micrometeorite bombardment on reflectance spectra in the mid ir in preparation for future space missions as well as for the mertis experiment onboard the bepicolombo mission for both irradiated samples we found a reduction in albedo and in the reflectance of characteristic reststrahlen bands and an increase of the transparency feature vis and nir spectra of both minerals show the typical darkening and reddening as described for other space weathered samples tem studies revealed that space weathered layers in olivine and pyroxene differ in their respective thickness 450 nm in olivine 100 250 nm in pyroxene as well as in developed nanostratigraphy of laser ablated material like nanophase iron npfe in conclusion our spectral and structural findings were compared to samples in which space weathering was caused by different processes a comparison with these data demonstrates that there is no difference in optical reflectance spectroscopy but a significant difference in the microstructure of minerals due to the weathering source in space as there are solar wind and solar flares cause other structural and chemical changes as the bombardment with micrometeorites

effects of glass content and oxidation on the spectra of snc like basalts applications to mars remote sensing 1 we have investigated the effects of crystallization and oxidation on the visible and near infrared visnir and mid infrared mid ir spectra of materials with a shergotty nakhla chassigny snc basaltic composition in order to investigate potential links between martian visnir spectra martian mid ir spectra and snc meteorite data snc basalt samples of varying crystallinities were synthesized and subsequently oxidized in air at 700 c for 1 7 days and reflectance spectra of both fine 75 m and coarse 75 500 m basalt samples were obtained before and after oxidation the effects of crystallization on the spectral properties are readily observed in the unoxidized products in the visnir increasing crystallization is accompanied by an increasing influence of pyroxene absorptions and decreasing influence of glass absorptions in the mid ir changes in spectral properties with crystallization are due to the variations in relative amounts of glass pyroxene and plagioclase oxidation alters the glass and pyroxenes within the samples leading to changes in visnir and mid ir spectral shapes although distinct signatures of oxidation products are not always observed both spectral and electron microscopy data indicate that hematite is the dominant oxidation product in the pigeonite and glass of the samples in pigeonite hematite is present in nanophase form and leads to the diminishment of the diagnostic 1 and 2 m pyroxene absorptions in the visnir as well as pyroxene absorptions expressed between 800 and 1100 cm 1 in the mid ir in glass hematite forms a near surface layer that is detected with varying efficiencies in the visnir and mid ir depending on the crystallinity and particle size of the analyzed sample oxidized snc basalt samples of various crystallinities and fine grain sizes provide the best analogs to mars remote sensing data in the visnir and mid ir in the visnir partially crystalline oxidized snc basalts can reproduce martian dark region characteristics in the mid ir similarities exist between the spectra of a partially crystalline oxidized snc basalt and the basalt lithology detected by the thermal emission spectrometer tes the andesite lithology detected by tes is best matched by the spectrum of a fully crystalline oxidized snc basalt these results imply that plagioclase rich lithologies are not required by tes data and that observed variations in spectral character of dark regions across the martian surface can be explained by snc basalts influenced by oxidation coupled with variations in degree of crystallization

experimental petrology of the mars pathfinder rock composition constraints on the interpretation of martian reflectance spectra 1 experiments to determine the crystallization sequence of the mars pathfinder mpf rock composition have been carried out to explore the range of possible mineral assemblages in this sio2 rich 57 4 wt martian igneous rock recent mars global surveyor thermal emission spectrometer observations have suggested the presence of large volumes of andesitic lava covering the northern hemisphere of mars but this interpretation has been called into question experimentally produced mineral assemblages can be used to infer spectral characteristics that would exist in andesitic lavas similar in composition to the mpf rock the inferred spectra could then be used with remotely sensed data to further constrain the identity of surface rock types on mars we performed a series of experiments at 0 1 mpa at the quartz fayalite magnetite and iron quartz fayalite oxygen buffers and 100 mpa at the ni nio oxygen buffer using the calculated soil free mpf composition potential mineralogies for a lava with the mpf composition would be sio2 57 wt feo 18 wt rich glass plagioclase quartz augite and fe ti oxides a contoured pyroxene quadrilateral with band i and ii minima was used to predict pyroxene composition on the basis of reflectance spectra using the quadrilateral in reverse the augite produced in the experimental series should have band i and ii minima at 0 97 m and 2 15 m respectively the absence of the 1 m minima in the imager for mars pathfinder imp spectra could be due to masking phases possibly the fe ti oxides produced in our experiments at 1000 c

evidence for magma carbonate interaction beneath syrtis major mars 1 we used three methods spectral index mapping linear spectral mixture analysis and factor analysis and target transformation to determine if carbonate decomposition products including lime cao periclase mgo portlandite ca oh 2 and brucite mg oh 2 are present on the surface of mars using an expanded spectral library that includes decomposition products of calcite and magnesite we deconvolved a binned emissivity data set from the mars global surveyor thermal emission spectrometer mgs tes the deconvolution model indicates that anhydrous carbonates are not present at kilometer scales above the tes detection limit however carbonate decomposition products may be present at or above the tes detection limit in northeast syrtis major and several other small regions on mars the model results are supported by spectral index mapping and factor analysis and target transformation of tes data in this region the volcanic setting of the detections may indicate the interaction of syrtis major lavas with subsurface carbonates or alternatively the eruption of carbonate bearing lavas that were subsequently devolatilized by impacts or later lava flows

thermal infrared emission spectroscopy of the pyroxene mineral series the thermal infrared emissivity spectra of coarse particulate samples of compositions in the pyroxene series display reststrahlen features absorptions that distinguish not only orthorhombic from monoclinic structures but also major end members within the two structural groups as well as minerals within solid solution series the exact number of reststrahlen features observed and their positions are dependent on mineral structure and cation occupancy of the m1 and m2 sites end member quadrilateral pyroxenes mg2si2o6 fe2si2o6 ca mg fe si2o6 are easily distinguished from each other and from minerals in the nonquadrilateral series nafesi2o6 na al fe si2o6 lialsi2o6 furthermore among quadrilateral pyroxenes variations in mg mg fe are linearly correlated with several band locations as are variations in ca content in high ca clinopyroxenes in both quadrilateral and nonquadrilateral compositions christiansen feature positions are also diagnostic no correlations with minor constituents of the order of 0 05 atoms per formula unit were observed the detailed spectral characteristics of pyroxenes and their variability as a function of structure and cation occupancy are presented here with determinative curves for the identification of pyroxene composition these data have important implications for the interpretation of spectral data from both laboratory and remote sensing instruments because they should permit a more detailed determination of pyroxene composition in measured unknown pure mineral and bulk compositions dominated by surface scattering i e all particulates greater than 65 m and solid samples

evidence for locally derived ultramafic intracrater materials in amazonis planitia mars 1 we studied a dark intracrater feature in amazonis planitia using visible thermal and spectral data from the mars global surveyor mgs thermal emission spectrometer tes mgs mars orbiter camera moc and 2001 mars odyssey thermal emission imaging system ody themis instruments visible and thermal data indicate that there are heterogeneities within the dark feature at meter to kilometer scales and suggest that it represents eroded terrain containing inactive ripple like bed forms possibly armored or indurated as well as loose possibly actively saltating sediment in addition part of the dark intracrater material may be covered with dust either as an optically thin few microns thick layer or as thicker discontinuous patches the thermal properties of the dark material are consistent with a mixture of sand rock and bedrock whereas the rest of the crater floor has thermal characteristics of fine 35 m particulates spectral data indicate that the crater floor is covered by a layer of dust that is spectrally and compositionally similar to the globally homogenized surface dust in other high albedo regions on mars the mineralogy of the dark materials is mafic dominated modally by pyroxene and olivine however unlike other lithologies common in low albedo regions i e surface types i and ii its derived bulk chemistry indicates that it is an ultramafic lithology with the lowest silica content detected on mars to date sheet silicates and glasses are not identified above detection limits and as such the materials do not display evidence for significant chemical weathering the geomorphology and visible distribution of the dark intracrater materials combined with the lack of an obvious source in the region outside the crater suggest they are the product of erosion of a local source

mineralogy of martian atmospheric dust inferred from thermal infrared spectra of aerosols 1 we have utilized optical constants derived from thermal infrared spectra acquired by the mariner 9 infrared interferometer spectrometer m9 iris and mars global surveyor thermal emission spectrometer mgs tes during periods of relatively high dust low water ice opacity to generate synthetic transmission and emission spectra of the atmospheric dust using libraries of transmission and emission spectra of common rock forming minerals and their alteration products we applied a linear deconvolution algorithm to the spectra to model the dust mineralogy models of the m9 iris transmission data generally are of poor quality and the mineralogical results of these fits are unlikely to be valid fits to the tes transmission spectrum and tes and iris emission spectra are of better quality and suggest that the dust mineralogy is dominated by framework silicates feldspar and or zeolite with carbonate sulfate pyroxene and olivine identified near but below generalized detection limits evidence for phyllosilicates is not robust our results combined with those from in situ measurements and other visible to infrared spectral studies suggest that framework silicates probably feldspar dominate the dust mineralogy with lesser amounts of olivine pyroxene amorphous material hematite and magnetite and that the dust largely is the product of mechanical weathering of basaltic rocks with minor chemical alteration

cosmochemical and spectroscopic properties of northwest africa 7325 a consortium study this work is part of a project to build an infrared database in order to link ir data of planetary materials and therefore possible mercury material with remote sensing observations of mercury which will probably be obtained by the mertis instrument on the forthcoming bepicolombo mission the unique achondrite northwest africa nwa 7325 which has previously been suggested to represent the first sample from mercury was investigated by optical and electron microscopy and infrared and raman spectroscopy in addition the oxygen strontium xenon and argon isotopes were measured and the abundance of selected trace elements determined the meteorite is a cumulate rock with subchondritic abundances of hfse and ree and elevated sr contents which underwent a second heating and partial remelting process oxygen isotope measurements show that nwa 7325 plots in the ureilite field close to the alm a trachyandesitic fragment found in the unique almahata sitta meteorite breccia on the other hand mineralogical investigations of the pyroxenes in nwa 7325 provide evidence for similarities to the lodranites and acapulcoites furthermore the rock is weakly shocked and argon isotope data record ancient 4 5 ga plateau ages that have not been reset the sample records a cosmogenic exposure age of 19 ma systematics of rb sr indicate an extreme early volatile depletion of the precursor material similar to many other achondrite groups however despite its compositional similarities to other meteorite groups our results suggest that this meteorite is unique and unrelated to any other known achondrite group an origin for nwa 7325 as a sample from the planet mercury is not supported by the results of our investigation in particular the evidence from infrared spectroscopy indicates that a direct relationship between nwa 7325 and the planet mercury can be ruled out no acceptable spectral match between laboratory analyses and remote sensing observations from mercury has been obtained however we demonstrate that infrared spectroscopy is a rapid and nondestructive method to characterize mineral phases and thus an excellent tool for planetary surface characterization in space missions

two phases of post onset collision adakitic magmatism in the southern lhasa subterrane tibet and their tectonic implications

implications of shortening in the himalayan fold thrust belt for uplift of the tibetan plateau 1 recent research in the himalayan fold thrust belt provides two new sets of observations that are crucial to understanding the evolution of the himalayan tibetan orogenic system first u pb zircon ages and sm nd isotopic studies demonstrate that 1 greater himalayan medium to high grade metasedimentary rocks are much younger than true indian cratonic basement and 2 these rocks were tectonically mobilized and consolidated with the northern margin of gondwana during early paleozoic orogenic activity these observations require that greater himalayan rocks be treated as supracrustal material in restorations of the himalayan fold thrust belt rather than as indian cratonic basement in turn this implies the existence of greater himalayan lower crust that is not exposed anywhere in the fold thrust belt second a regional compilation of shortening estimates along the himalayan arc from pakistan to sikkim reveals that 1 total minimum shortening in the fold thrust belt is up to 670 km 2 total shortening is greatest in western nepal and northern india near the apex of the himalayan salient and 3 the amount of himalayan shortening is equal to the present width of the tibetan plateau measured in an arc normal direction north of the indus yalu suture zone this information suggests that a slab of greater indian lower crust composed of both indian cratonic lower crust and greater himalayan lower crust with a north south length of 700 km may have been inserted beneath the tibetan crust during the cenozoic orogeny we present a modified version of the crustal underthrusting model for himalayan tibetan orogenesis that integrates surface geological data recent results of mantle tomographic studies and broadband seismic studies of the crust and upper mantle beneath the tibetan plateau previous studies have shown that incremental mesozoic and early cenozoic shortening had probably thickened tibetan crust to 45 55 km before the onset of the main cenozoic orogenic event thus the insertion of a slab of greater indian lower crust with maximum thickness of 20 km tapering northward could explain the cenozoic uplift of the tibetan plateau the need for tibetan crust to stretch laterally as the greater indian lower crust was inserted may explain the widespread east west extension in the southern half of the plateau our reconstruction of the himalayan fold thrust belt suggests that indian cratonic lower crust of presumed mafic composition and high strength should extend approximately halfway across the tibetan plateau to the banggong suture from there northward we predict that the tibetan plateau is underlain by more felsic and therefore weaker lower crust of greater himalayan affinity two slab break off events are predicted by the model the first involved neotethyan oceanic lithosphere that foundered 45 35 ma and the second consisted of greater indian lithosphere most likely composed of greater himalayan material that delaminated and foundered 20 10 ma asthenospheric upwelling associated with the break off events may explain patterns of cenozoic volcanism on the tibetan plateau although the model predicts a northward migrating topographic front due solely to insertion of greater indian lower crust the actual uplift history of the plateau was complicated by early middle tertiary shortening of tibetan crust

mineralogical composition of sands in meridiani planum determined from mars exploration rover data and comparison to orbital measurements constraints on the mineralogical composition of low albedo low sulfur sands at meridiani planum are determined from mars exploration rover mer opportunity miniature thermal emission spectrometer mini tes mossbauer and alpha proton x ray spectrometer measurements results of this work show that the sand is olivine basaltic in composition with minor amounts of sulfate and a high silica phase glass or secondary amorphous silica measurements from all three instruments indicate that pyroxene is twice as abundant as olivine and that the pyroxene composition is dominated by the low calcium variety the volume abundance of olivine is constrained to be 10 15 results from detailed analyses of mer data are used to ground truth the spectral emissivity and mineral abundances derived from orbit with mars global surveyor tes data tes derived mineral abundances are within 5 of those derived from mer data which is generally within the statistical errors associated with tes derived phase abundances the agreement lends support to global and regional scale variations in mineralogical composition determined from tes data in previous studies an alternative method of least squares minimization is used for modeling the tes and mini tes data the benefits of this method are demonstrated by comparison with conventional least squares techniques previously used by tes data users

thermal infrared emissivity measurements under a simulated lunar environment application to the diviner lunar radiometer experiment 1 we present new laboratory thermal infrared emissivity spectra of the major silicate minerals identified on the moon measured under lunar environmental conditions and evaluate their application to lunar remote sensing data sets thermal infrared spectral changes between ambient and lunar environmental conditions are characterized for the first time over the 400 1700 cm 1 6 25 m spectral range for a fine particulate mineral suite including plagioclase albite and anorthite pyroxene enstatite and augite and olivine forsterite the lunar environment introduces observable effects in thermal infrared emissivity spectra of fine particulate minerals which include 1 a shift in the christiansen feature cf position to higher wave numbers shorter wavelengths 2 an increase in the overall spectral contrast and 3 decreases in the spectral contrast of the reststrahlen bands and transparency features our new measurements demonstrate the high sensitivity of thermal infrared emissivity spectra to environmental conditions under which they are measured and provide important constraints for interpreting new thermal infrared data sets of the moon including the diviner lunar radiometer experiment onboard nasa s lunar reconnaissance orbiter full resolution laboratory mineral spectra convolved to diviner s three spectral channels show that spectral shape cf position and band ratios can be used to distinguish between individual mineral groups and lunar lithologies the integration of the thermal infrared cf position with near infrared spectral parameters allows for robust mineralogical identifications and provides a framework for future integrations of data sets across two different wavelength regimes

investigating the shock histories of lunar meteorites miller range 090034 090070 and 090075 using petrography geochemistry and micro ftir spectroscopy fourier transform infrared ftir spectroscopy and cathodoluminescence cl imaging techniques combined with electron microprobe analyses have been used to determine the physical state of feldspathic phases that have been subject to varying levels of shock in the grouped lunar meteorites miller range 090034 090070 and 090075 six feldspathic phases have been identified based on spectral textural and chemical properties a specific infrared wavelength band ratio 1064 932 cm 1 equivalent to 9 40 10 73 m chosen because it can distinguish between some of the feldspathic phases can be used to estimate the pressure regimes experienced by these phases in addition ftir spatial mapping capabilities allow for visual comparison of variably shocked phases within the samples by comparing spectral and compositional data the origin and shock history of this lunar meteorite group has been determined with each of the shocked feldspathic phases being related to events in its geological evolution as such we highlight that ftir spectroscopy can be easily employed to identify shocked feldspathic phases in lunar samples estimate peak shock pressures and when compared with chemical data can be used to investigate their shock histories

can slab melting be caused by flat subduction slab melting has been suggested as a likely source of adakitic arc magmas i e andesitic and dacitic magmas strongly depleted in y and heavy rare earth elements existing numerical and petrologic models however restrict partial melting to very young 5 ma oceanic crust typically at 60 80 km depth paradoxically most of the known pliocene quaternary adakite occurrences are related to subduction of 10 45 ma lithosphere which should not be able to melt under normal subduction zone thermal gradients we propose an unusual mode of subduction known as flat subduction occurring in 10 of the world s convergent margins that can produce the temperature and pressure conditions necessary for fusion of moderately old oceanic crust of the 10 known flat subduction regions worldwide eight are linked to present or recent 6 ma occurrences of adakitic magmas observations from chile ecuador and costa rica suggest a three stage evolution 1 steep subduction produces a narrow calc alkaline arc typically 300 km from the trench above the asthenospheric wedge 2 once flat subduction begins the lower plate travels several hundred kilometers at nearly the same depth thus remaining in a pressure temperature window allowing slab melting over this broad distance and 3 once flat subduction continues for several million years the asthenospheric wedge disappears and a volcanic gap results as in modern day central chile or peru the proposed hypothesis which reconciles thermal models with geochemical observations has broad implications for the study of arc magmatism and for the thermal evolution of convergent margins

global spectral classification of martian low albedo regions with mars global surveyor thermal emission spectrometer mgs tes data 1 martian low albedo surfaces defined here as surfaces with mars global surveyor thermal emission spectrometer mgs tes albedo values 0 15 were reexamined for regional variations in spectral response low albedo regions exhibit spatially coherent variations in spectral character which in this work are grouped into 11 representative spectral shapes the use of these spectral shapes in modeling global surface emissivity results in refined distributions of previously determined global spectral unit types surface types 1 and 2 pure type 2 surfaces are less extensive than previously thought and are mostly confined to the northern lowlands regional scale spectral variations are present within areas previously mapped as surface type 1 or as a mixture of the two surface types suggesting variations in mineral abundance among basaltic units for example syrtis major which was the surface type 1 type locality is spectrally distinct from terrains that were also previously mapped as type 1 a spectral difference also exists between southern and northern acidalia planitia which may be due in part to a small amount of dust cover in southern acidalia groups of these spectral shapes can be averaged to produce spectra that are similar to surface types 1 and 2 indicating that the originally derived surface types are representative of the average of all low albedo regions

surface mineralogy of martian low albedo regions from mgs tes data implications for upper crustal evolution and surface alteration 1 mars global surveyor thermal emission spectrometer mgs tes data are used to derive the modal mineralogy of spectrally distinct martian low albedo regions and to identify spatial trends in mineralogic assemblages results from this work are consistent with the major results of previous spectroscopic studies 1 plagioclase and clinopyroxene are the dominant minerals of most southern highlands regions 2 the northern plains exhibit the lowest pyroxene abundance within martian low albedo regions and 3 the highest concentrations of high silica phase s are found in the northern plains solis planum and a few southern high latitude regions low albedo regions may be classified into four units on the basis of relative abundances of plagioclase pyroxene and high silica phase s unit distributions between 45 latitude exhibit moderate correlation with distinct provinces e g syrtis major aonium sinus defined by large scale morphology elevation and to some extent surface age suggesting that the spectral and compositional differences between these units are more strongly controlled by original bedrock mineralogy than by surface atmosphere interactions and alteration syrtis major exhibits a difference in mineralogy from the surrounding highlands suggesting a differing degree of fractional crystallization assimilation or source region composition areas with thick crust near the tharsis plateau exhibit lower abundances of olivine and greater plagioclase pyroxene ratios than surrounding highland terrains suggesting that magmas in this region may have undergone increased olivine fractionation regions where surface alteration is more likely to be the primary control on observed spectral signatures are the high latitude areas 45 where globally surfaces dominated by high silica phase s are most commonly found

geologic characteristics of relatively high thermal inertia intracrater deposits in southwestern margaritifer terra mars 1 twenty one craters in southwestern margaritifer terra exhibit unusually warm interior deposits in nighttime thermal emission imaging system themis infrared images these deposits exhibit nighttime temperatures as high as 223 k and are 5 18 warmer than the surrounding plain thermal inertia values derived from thermal emission spectrometer tes data are greater for the deposits than the plains with maximum values between 455 and 675 j m 2 k 1 s 1 2 analysis of themis thermal inertia data having nearly an order of magnitude better spatial resolution shows that the deposits can have a thermal inertia as high as 1060 j m 2 k 1 s 1 2 albedo and dust cover index values suggest that both the deposits and the surrounding region are generally dust free compositional analysis with tes and themis data show that though a small number of the deposits may have isolated compositional differences the majority of the deposits have a composition similar to that of the surrounding plains the geomorphology of the craters as viewed from mars orbiter camera moc images shows that the deposits are coherent units rather than sand deposits an observation that is consistent with the relatively high thermal inertia values if these deposits are coherent rock units as the results of our study suggest possible methods of formation include emplacement of primary igneous material or lithification of sediments from surrounding terrain

determining the modal mineralogy of mafic and ultramafic igneous rocks using thermal emission spectroscopy the modal mineralogies of 20 mafic and ultramafic igneous rocks were determined from their thermal infrared emission spectra using a linear deconvolution approach which uses a library of end member mineral spectra to model a bulk rock spectrum over 90 of the modes obtained from thermal emission spectra agree with modes obtained by traditional optical analyses to within the stated error of the optical analyses 5 15 vol library spectra of several compositions within a solid solution series e g plagioclase feldspars labradorite and bytownite were commonly used in each best fit model and are assumed to represent in combination a composition in the rock for which an identical mineral spectrum was unavailable in the library the accuracy of this assumption was evaluated by calculating a weighted average solid solution composition for plagioclase and or pyroxenes from the library minerals used in the model best fit of 14 rocks and comparing these compositions to the actual chemistries measured by electron microprobe or the optically estimated an the derived solid solution compositions are generally within 10 15 an or mg of the measured composition modal data derived from the spectra via the deconvolution were summed and converted to weight percent wt oxides for comparison to standard bulk chemistry data sio2 al2o3 and na2o k2o were generally slightly overestimated and feo and mgo were typically slightly underestimated modes and wt oxides were plotted on standard rock type classification diagrams and provide broadly accurate classifications demonstrating that the linear deconvolution technique is successful at deriving useful mineralogical information from thermal infrared emission spectra of bulk rock samples furthermore convolution of the laboratory data to spectral resolutions comparable to remote sensing instruments specifically the mars global surveyor thermal emission spectrometer demonstrates only a 5 vol increase in modal uncertainty for minerals present in abundances 10 vol this study thus provides a strong foundation for the application of this technique to mafic igneous sample spectra from both laboratory and remote sensing instruments