structural controls on sulfide mobilization at the high grade flying fox ni cu pge sulfide deposit forrestania greenstone belt western australia the flying fox komatiite hosted ni deposit is located in the forrestania greenstone belt of the yilgarn craton in western australia the host volcanosedimentary succession has been metamorphosed to amphibolite facies and deformation has sheared and dismembered the orebody creating 11 distinct ore shoots the ore shoots are hosted at the base of a komatiite sequence structurally overlying deformed metasedimentary rocks the ni sulfide orebody has undergone six phases of deformation 1 d 1areg e w compression resulted in tilting of the stratigraphy 2 d 1bff continued e w compression resulted in coaxial flattening along the footwall sedimentary rock sulfide komatiite contact and the basalt hanging wall sedimentary rock contact 3 d 2ff ene wsw compression resulted in noncoaxial shearing of the d 1bff structures 4 d 3ff ese wnw compression resulted in shallow angle thrusts 5 d 4ff during e w extension normal ductile brittle faults formed by the pooling and dilation of granitic magma along the f 2 structural contact between the footwall sedimentary and komatiite rocks and 6 d 5ff intrusion of a proterozoic dolerite dike during n s extension accompanied by late stage brittle normal faulting during deformation the ni sulfides reverted to monosulfide solid solution mss and were mechanically relocated along the footwall sedimentary rock komatiite contact offset into the footwall sedimentary rocks and entrained in the granitic magma creating atypical granite hosted sulfides the ni sulfides were mobilized up to 5 m away from the ultramafic rocks during the d 1 and d 2 events however subsequent dismemberment of the original orebody into separate ore shoots along flat lying faults during the d 3 event led to offsets of up to 300 m the detailed structural analysis of the flying fox deposit has shown that restoration of the lithostratigraphy along known faults can be used to define the volcanic stratigraphy including primary ni ore horizons this information can be used as a guide to the location of concealed extensions to known ore shoots or completely unknown orebodies at depth or along strike

bidirectional visible nir and biconical ft ir reflectance spectra of almahata sitta meteorite samples abstract bidirectional visible and near infrared and off axis biconical fourier transform infrared reflectance spectra of almahata sitta meteorite stone samples fragments of asteroid 2008 tc3 have been measured these meteorites represent the first freshly fallen polymict ureilites available for such studies although the chip samples show varying degrees of terrestrial weathering depending on their environment on earth many of them are much fresher than other ureilites known to date the majority of the almahata sitta chips studied here show only a weak near uv absorption a flat spectrum at visible and near ir wavelengths and varying depths of the 1 and 2 m pyroxene and olivine bands the astronomical reflectance observations of the asteroid 2008 tc3 over the range 0 55 1 0 m provide a constraint on what a combination of the measured spectra can represent in the surface reflectance of the asteroid over the 0 32 2 55 m range measured in this study most of the recovered samples of almahata sitta have textures and albedos similar to stones 27 largest recovered fragment 4 and 47 results of linear least square fits of the asteroid 2008 tc3 spectrum with two sets of the meteorite spectra suggest that the asteroid had 10 12 albedo and no fine regolith on its surface we note that other lithologies may be at the surface of other fragments of the asteroid family from which 2008 tc3 originated in that case reflectance spectra could vary significantly among family members

reflectance spectra of the elephant moraine a79001 meteorite implications for remote sensing of planetary bodies abstract eeta 79001 a shergottite meteorite includes a pair of nonbrecciated basaltic lithologies joined along a planar igneous contact these two lithologies a and b are examples of the type of basaltic contacts likely to occur on the surfaces of many planetary bodies as such eeta 79001 offers a unique opportunity to compare analysis techniques available in situ with those available remotely for comparison to petrologic and geochemical studies reflectance spectra of lithologies a and b are obtained and analyzed with the modified gaussian model mgm this modeling leads to the unambiguous identification of two pyroxene phases in each lithology all spectral features including an absorption near 1 2 m often attributed to plagioclase are found to be due solely to the presence of two pyroxenes this ambiguity between pyroxene and plagioclase absorptions suggest that caution be used in interpretation of remote spectra results from the mgm analysis of spectra of eeta 79001 are also used to provide estimates on the major element composition of the pyroxene phases in the two lithologies in addition based solely on spectral analyses lithology b is shown to have 11 17 more high calcium pyroxene relative to low calcium pyroxene than lithology a each of the results derived independently with the mgm are shown to compare favorably within 5 10 to those obtained from more traditional geochemical and petrographic methods the compositional inferences that were derived from modeling the spectra of eeta 79001 with the mgm are examples of the type of information available from remotely acquired spectral data by providing a method for determining changes in relative composition and abundance of pyroxenes in neighboring units the mgm offers an opportunity to add compositional information to geologic and morphologic data and thus greatly enhance the science return on studies of surfaces throughout the solar system

the nickel sulfide mineralization and metamorphic setting of the forrestania area western australia the forrestania group of nickel sulfide occurrences of the archean southern cross province is localized in intrusive dunite bodies at the base of a lower komatiite unit which is interlayered with tholeiitic mafic rocks para amphibolites quartz biotite schists chemical sedimentary rocks iron formation and sulfide cherts and komatiites concordant lenticular metamor phosed sill like mineralized dunites have komatiitic affinities and appear to be feeder chambers to overlying thick sequences of dominantly extrusive ultramafic komatiites and rare pyroclastic komatiites unmineralized portions of the dunites are extremely rich in magnesium with mgo values ranging between 45 and 51 percent the important nickel sulfide occurrences are pentlandite rich disseminations distributed in the basal portions of metamorphosed intrusive dunites e g cosmic boy and digger rocks south digger rocks similar mineralization also occurs in hanging wall and internal portions of dunites but is generally of less importance than the basal mineralization because of lower nickel tenor massive pyrrhotite rich sulfides occur within reaction zones between dunite and footwall country rocks and as remobilized veins and stringers in footwall metasediments this type of mineralization forms important small tonnage high grade deposits at new morning and flying fox supergene alteration of primary sulfides is extensive and massive violarite pyrite magnetite zones are developed in weathering profiles polyphase deformation and metamorphism with peak conditions estimated at 655 degrees or 30 degrees c and 4 0 or 1 0 kb resulted in widespread recrystallization and tectonic remobilization of ductile sulfides cumulate dunites were metamorphosed to bladed granular and granoblastic aggregates of forsterite talc forsterite talc anthophyllite and forsterite talc enstatite formed under varying f sub co 2 and f sub h 2 o conditions retrograde serpentinization and talc carbonate alteration followed by later supergene alteration has caused textural modification and oxidation of primary sulfides with development of pyrite violarite and magnetite rich ores nickel values and ni cu ratios vary for different types of mineralization the economically important basal disseminations of pentlandite pyrite pyrrhotite chalcopyrite have ni values in the range 2 to 5 percent and constant ni cu ratios in the range 14 1 to 22 1 bulk composition of primary sulfides of this type at cosmic boy is s rich with fe 39 4 percent ni co 18 6 percent and s 42 0 percent massive remobilized veins of pyrrhotite pentlandite pyrite chalcopyrite have high ni 3 to 8 and erratic ni cu ratios generally in the range from 10 1 to 200 1 with a mean of 45 1 this mineralization is fe rich with fe 50 4 percent ni co 7 4 percent and s 42 2 percent broad irregular sparse disseminations less than 2 of pentlandite heazlewood chalcopyrite form in the internal portions of cumulate and metamorphosed dunites they have low ni 0 3 to 0 5 high ni cu ratio 50 1 to 100 1 and bulk composition close to pentlandite composition with fe 31 8 percent ni co 34 2 percent and s 34 0 percent the bulk compositions of sulfides generally plot on the s rich side of the monosulfide solid solution field at 650 degrees c and this appears to reflect nickel and sulfur mobility during retrograde metamorphism

mineralogical and geochemical analyses of antarctic lake sediments a study of reflectance and mossbauer spectroscopy and c n and s isotopes with applications for remote sensing on mars abstract we analyzed lake bottom sediments from the dry valleys region of antarctica to study the influence of water chemistry on the mineralogy and geochemistry of these sediments as well as to evaluate techniques for remote spectral identification of potential biomarker minerals on mars lakes from the dry valleys region of antarctica have been investigated as possible analogs for extinct lake environments on early mars sediment cores were collected in the present study from perennially ice covered lake hoare in the taylor valley these sediments were taken from a core in an oxic region of the lake and another core in an anoxic zone differences between the two cores were observed in the sediment color fe ii fe iii ratio the presence of pyrite the abundance of fe s and some trace elements and the c n and s isotope fractionation patterns the results of visible infrared reflectance spectroscopy 0 3 25 m mossbauer spectroscopy 77 and 4 k and x ray diffraction are combined to determine the mineralogy and composition of these samples the sediments are dominated by plagioclase k feldspar quartz and pyroxene algal mats grow on the bottom of the lake and organic material has been found throughout the cores calcite is abundant in some layers of the sediment core from the shallow oxic region and pyrite is abundant in the upper sediment layers of the core from the deep anoxic region of lake hoare analysis of the spectroscopic features due to organics and carbonates with respect to the abundance of organic c and carbonate contents was performed in order to select optimal spectral bands for remote identification of these components in planetary regoliths carbonate bands near 4 and 6 8 m 2500 and 1500 cm 1 were detected for carbonate abundances as low as 0 1 wt co2 organic features at 3 38 3 42 and 3 51 m 2960 2925 and 2850 cm 1 were detected for organic c abundances as low as 0 06 wt c the 13c and 15n trends show a more complex organic history for the anoxic region sediments than for the oxic region sediments the biogenic pyrite found in the core from the anoxic zone is associated with depleted 34s values and high organic c levels and could be used as a potential biomarker mineral for paleolakes on mars

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

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

recognition of minor constituents in reflectance spectra of allan hills 84001 chips and the importance for remote sensing on mars reflectance spectra of splits 92 and 271 from the martian meteorite allan hills alh 84001 are presented and analyzed in this paper although the visible and infrared spectra of both chips show that the dominant mineralogy is low ca pyroxene the focus here is on identification of the minor constituents infrared spectra measured at multiple spots along the surface of chips 92 and 271 show subtle spectroscopic variations due to changes in the low ca pyroxene texture and composition and to the presence of secondary minerals absorption bands observed near 0 93 and 1 95 m are characteristic of low ca pyroxene strong mid infrared reststrahlen bands are observed near 9 and 19 5 m in all surface spectra and additional bands near 7 10 5 11 4 17 8 20 5 and 23 m are variable depending on the low ca pyroxene texture and the presence of secondary minerals selected spectra exhibit carbonate features near 4 6 4 7 1 and 11 3 m detailed analysis of these carbonate features indicates the presence of mg fe carbonate which is consistent with petrographic studies many of these spectra with strong carbonate features exhibit a magnetite feature near 17 9 m and a shoulder near 20 5 m that cannot be uniquely ascribed to one mineral spectroscopic identification of the minor carbonate and magnetite minerals in this probable piece of mars indicates that detection of small amounts of these minerals of possible biological significance will be possible using infrared hyperspectral analyses of the martian surface also of importance for remote sensing on mars is the result that mg fe and mg fe carbonates in a low ca pyroxene matrix should be distinguishable from one another in the spectral region measured by the thermal emmitance spectrometer tes

p wave velocity features of the lithosphere under the eromanga basin eastern australia including a prominent mid crustal conrad discontinuity abstract the crustal structure of the central eromanga basin in the northern part of the australian tasman geosyncline revealed by coincident seismic reflection and refraction shooting contrasts with some neighbouring regions of the continent the depth to the crust mantle boundary moho of 36 41 km is much less than that under the north australian craton to the northwest 50 55 km and the lachlan fold belt to the southeast 43 51 km but is similar to that under the drummond and bowen basins to the east the seismic velocity boundaries within the crust are sharp compared with the transitional nature of the boundaries under the north australian and lachlan provinces in particular there is a sharp velocity increase at mid crustal depths 21 24 km which has not been observed with such clarity elsewhere in australia the conrad discontinuity in the lower crust the many discontinuous sub horizontal reflections are in marked contrast to lack of reflecting horizons in the upper crust further emphasising the differences between the upper and lower crust the crust mantle boundary moho is characterised by an increase in velocity from 7 1 7 7 km s to a value of 8 15 0 04 km s the depth to the moho under the canaway ridge a prominent basement high is shallower by about 5 km than the regional moho depth there is also no mid crustal horizon under the canaway ridge but there is a very sharp velocity increase at the moho depth of 34 km the ridge could be interpreted as a horst structure extending to at least moho depths but it could also have a different intra crustal structure from the surrounding area the sub crustal lithosphere has features which have been interpreted from limited data as being caused by a velocity gradient at 56 57 km depth with a low velocity zone above it because of the contrasting crustal thicknesses and velocity gradients the lithosphere of the central eromanga basin cannot be considered as an extension of the exposed lachlan fold belt or the north australian craton the lack of seismic reflections from the upper crust indicates no coherent accoustic impedance pattern at wavelengths greater than 100 m consistent with an upper crustal basement of tightly folded meta sedimentary and meta volcanic rocks the crustal structure is consistent with a pericratonic or arc back arc basin being cratonised in an episode of convergent tectonics in the early palaeozoic the seismic reflections from the lower crust indicate that it could have developed in a different tectonic environment

hydrothermal formation of clay carbonate alteration assemblages in the nili fossae region of mars abstract the compact reconnaissance imaging spectrometer for mars crism has returned observations of the nili fossae region indicating the presence of mg carbonate in small

candidates source regions of martian meteorites as identified by omega mex abstract the objective of this study is to identify and map spectral analogues of some key martian meteorites basaltic shergottites los angeles shergotty que 94201 lherzolitic shergottite alh a77005 nakhla chassigny and the orthopyroxenite alh 84001 in order to localize terrain candidates for their source regions we develop a best fit procedure to reproduce the near infrared nir spectral properties of the martian surface as seen by the hyperspectral imaging spectrometer omega mex from the nir spectra of the martian meteorites the fitting process is tested and validated and root mean square rms global maps for each meteorite are obtained it is found that basaltic shergottites have nir spectral properties the most representative of the martian surface with the best spectral analogues found in early hesperian volcanic provinces sites with spectral properties similar to those of alh a77005 are scarce they are mainly localized in olivine bearing regions such as nili fossae and small noachian early hesperian terrains the only plausible source region candidate for chassigny is the nili patera caldera dated to 1 6 ga widespread spectral analogues for the alh 84001 meteorite are found northeast of syrtis major and northwest of the hellas basin while this distribution is in agreement with the low calcium pyroxene rich composition and old age 4 1 ga of this meteorite the modal mineralogy of these candidates is not consistent with that of this meteorite no convincing spectral analogue is found for the amazonian aged nakhla meteorite suggesting that its olivine high calcium pyroxene rich composition could be representative of the amazonian terrains buried under dust finally some young rayed craters are proposed as possible candidates for source craters of the studied martian meteorites

seeing through the dust martian crustal heterogeneity and links to the snc meteorites through the application of new analytical techniques to high spatial resolution imaging spectrometer data the ferrous mineralogy of major volcanic terrains on mars is shown to consist of significant fractions of both low and high calcium pyroxene changes in the relative abundances of these pyroxenes are observed for units of different age and morphology even in regions with higher degrees of alteration and contamination from dust volcanic rocks with these characteristics are uncommon on earth but are typical of the basaltic snc meteorites shergottites nakhlites and chassignites thought to be from mars thus it is possible to infer even through the veil of dust that the snc meteorites have mineralogic affinities to major volcanic provinces on mars and are therefore truly representative of the heterogeneity observed on the surface of the red planet

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

spectroscopic analysis of martian meteorite allan hills 84001 powder and applications for spectral identification of minerals and other soil components on mars spectroscopic measurement and analysis of martian meteorites provide important information about the mineralogy of mars as well as necessary ground truths for deconvolving remote sensing spectra of the martian surface rocks the spectroscopic properties of particulate alh 84001 from 0 3 to 25 m correctly identify low ca pyroxene as the dominant mineralogy absorption bands due to electronic transitions of ferrous iron are observed at 0 94 and 1 97 m that are typical for low ca pyroxene a strong broad water band is observed near 3 m that is characteristic of the water band typically associated with pyroxenes weaker features near 4 8 5 2 and 6 2 m are characteristic of particulate low ca pyroxene and can be distinguished readily from the features due to high ca pyroxene and other silicate minerals the reflectance minimum occurs near 8 6 m for the alh 84001 powder which is more consistent with high ca pyroxene and augite than low ca pyroxene the dominant mid infrared ir spectral features for the alh 84001 powder are observed near 9 and 19 5 m however there are multiple features in this region these mid ir features are generally characteristic of low ca pyroxene but cannot be explained by low ca pyroxene alone spectral features from 2 5 5 m are typically associated with water organics and carbonates and have been studied in spectra of the alh 84001 split 92 powder and alh 84001 splits 92 and 271 chip surfaces weak features have been identified near 3 5 and 4 m that are assigned to organic material and carbonates another feature is observed at 4 27 m in many surface spots and in the powder but has not yet been uniquely identified spectroscopic identification of minor organic and carbonate components in this probable piece of mars suggests that detection of small amounts of organics and carbonates in the martian surface regolith would also be possible using visible infrared hyperspectral analyses laboratory spectroscopic analysis of martian meteorites provides a unique opportunity to identify the spectral features of minerals and other components while they are embedded in their natural medium

spectral reflectance of martian meteorites spectral signatures as a template for locating source region on mars we report the spectral reflectance of martian meteorites from 0 3 2 6 microns for the purpose of cataloguing spectra and the association of their spectral properties with mineralogy and petrology we fit the spectra to a series of overlapping modified gaussian absorptions using least squares fitting the results are validated against established relationships between photon interactions with mineral chemistry and the band parameters these resultant band parameters can be used to constrain interpretations of martian reflectance spectra in the search for the source region of meteorites from mars the limitations of the fitting method are discussed

thermal infrared emission spectroscopy of anhydrous carbonates the objective of this study is to present the thermal emission spectra of various anhydrous calcite and dolomite series carbonate minerals to illustrate the effect of the structural cation ca 2 mg 2 fe 2 mn 2 zn 2 on shifting the positions of the carbonate absorption bands all of the carbonate mineral emission spectra included in this study exhibit three absorption features related to three specific vibrational modes of the carbonate anion co 3 2 these anion vibrations include the out of plane bend the asymmetric stretch and the in plane bend i e the 2 3 and 4 modes respectively the positions of the absorption band emissivity minima are unique for each carbonate chemistry and are thus diagnostic of mineralogy the average 2 3 and 4 wavenumber positions for the various carbonate minerals are as follows calcite caco 3 883 1523 and 712 cm 1 magnesite mgco 3 901 1572 and 748 cm 1 siderite feco 3 876 1523 and 736 cm 1 rhodochrosite mnco 3 877 1535 and 726 cm 1 smithsonite znco 3 882 1509 and 742 cm 1 dolomite camg co 3 2 894 1547 and 728 cm 1 and kutnahorite camn co 3 2 882 1526 and 716 cm 1 carbonates as a general mineral class crystallize in a variety of geological environments however each specific carbonate mineralogy typically is limited to a narrow range of geologic settings in which it forms thermal infrared emission data to be received from the mars global surveyor thermal emission spectrometer will contain the spectral signature of carbonates if they are present above the detectibility limit on the surface of mars this study presents the spectral information necessary to recognize carbonate as a mineral class as well as identify the specific type of carbonate from thermal emissivity data knowledge of distinct carbonate mineralogy will be useful for interpreting the environmental conditions that were present on mars during the carbonate formation the result of this study is that the major carbonate mineral species calcite dolomite magnesite siderite and smithsonite can be identified from thermal infrared emission data provided moderate 10 cm 1 spectral sampling because of the similarity of absorption band positions between kutnahorite and calcite high 2 cm 1 spectral sampling is required to distinguish kutnahorite moderate spectral sampling data are also sufficient to determine the amount of mg and fe in mg fe solid solution minerals to within 3 5 of the cation abundance

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

joint analysis of ism and tes spectra the utility of multiple wavelength regimes for martian surface studies utility of these data sets they need to be joined to provide pan spectral coverage of the surface of mars that will give information on different types of absorption processes in surface materials we have performed a test of this approach using ism and tes data to provide near infrared and thermal infrared coverage of the selected regions observed by both instruments gridding and registering the two data sets to a common reference allows investigations of regional and global properties of the surface here we investigate the variability in the spectral properties of low albedo regions particularly type i basaltic and type ii regions and relate these variations to probably mineralogic composition ism and tes data agree on the presence of pyroxenes in type i regions but may indicate a lack of pyroxene in the type ii material although this is inconclusive type i regions in general appear to be uniform in composition and surface variations are primarily controlled by mixing with dust temporal variations in surface reflectance make analysis of the differences in spectral properties between eastern and western syrtis major difficult but indicate that slope differences may not be due to intimate cementing of dark and light materials but rather due to penetrative oxidation of the surfaces of basaltic materials these results demonstrate that the complementary strengths of multiple wavelength regimes allow greater understanding of surface composition and processes

hydrous carbonates on mars evidence from mariner 6 7 infrared spectrometer and ground based telescopic spectra absorption features at 2 28 and 5 4 m identified in mariner 6 7 infrared spectrometer and terrestrial telescopic spectra are consistent with the spectra of hydrous magnesium carbonates such as hydromagnesite and artinite spectral characteristics of these hydrous carbonates are different from those of the anhydrous carbonates as the former do not have the strong spectral features typically associated with anhydrous carbonates such as calcite and siderite theoretical mixing indicates that depending on the type of hydrous carbonate 10 20 wt can be incorporated into the regolith without contradicting the spectral observations or the viking x ray fluorescence chemical analysis hydrous carbonates form as weathering products of mafic minerals in the presence of h2o and co2 even in the antarctic their formation as evaporite minerals from either original magmas or hydrothermally altered rocks is consistent with the martian environment provided liquid water is or has been at least transiently present on earth formation of hydrous mg carbonates is associated with the production of amorphous iron oxides which is consistent with both the environment and the inferred surface mineralogy of mars these minerals are about 60 wt h2o co3 and oh if they are abundant everywhere at the 10 level then about 6 of the surface weight could be volatiles bound in this type of mineral although the stability of hydrous carbonates in a martian environment is uncertain there may be kinetic factors inhibiting the dehydration of these minerals which may persist metastably in the current environment although the spectroscopic evidence for anhydrous carbonates is scant the possible presence of hydrous carbonates provides an appealing mechanism for the existence of carbonates on mars

up down or sideways emplacement of magmatic fe ni cu pge sulfide melts in large igneous provinces the preferential localization of fe ni cu pge sulfides within the horizontal components of dike sill lava flow complexes in large igneous provinces lips indicates that they were fluid dynamic tra

determination of martian meteorite lithologies and mineralogies using vibrational spectroscopy we have acquired thermal infrared emission spectra of four martian meteorite samples alh77005 nakhla zagami and eet79001 representing three major lithologies iherzolite clinopyroxenite and basalt the spectra of these meteorites are significantly different from each other and we can distinguish the three lithologies easily on the basis of their spectral morphologies using a linear deconvolution model the modal mineralogies of alh77005 nakhla and zagami were derived from their spectra to within 2 19 of the modes derived by optical methods for zagami and eet79001 the correct mineral types were identified as present using the linear method although an exact spectral match using available end member spectra was not obtained probably due to the lack of a pigeonite end member spectrum or shock effects in the meteorites the meteorite spectra we have acquired will be used for comparison with data to be returned by the thermal emission spectrometer tes on the mars global surveyor orbiter and would also be useful for comparing to future rover or lander based thermal ir spectra based on our results comparisons of mineral end member and meteorite spectra with tes spectra of coarse regolith and rocky regions should aid identification and mapping of martian surface lithologies and unit mineralogy

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

orbital evidence for more widespread carbonate bearing rocks on mars carbonates are key minerals for understanding ancient martian environments because they are indicators of potentially habitable neutral to alkaline water and may be an important reservoir for paleoatmospheric co 2 previous remote sensing studies have identified mostly mg rich carbonates both in martian dust and in a late noachian rock unit circumferential to the isidis basin here we report evidence for older fe and or ca rich carbonates exposed from the subsurface by impact craters and troughs these carbonates are found in and around the huygens basin northwest of hellas in western noachis terra between the argyre basin and valles marineris and in other isolated locations spread widely across the planet in all cases they cooccur with or near phyllosilicates and in huygens basin specifically they occupy layered rocks exhumed from up to 5 km depth we discuss factors that might explain their observed regional distribution arguments for why carbonates may be even more widespread in noachian materials than presently appreciated and what could be gained by targeting these carbonates for further study with future orbital or landed missions to mars

geochemistry of komatiites from forrestania southern cross province western australia evidence for crustal contamination the 2 9 ga old forrestania greenstone belt is intermediate in character between typical 3 0 ga and 2 7 ga belts in containing both al depleted and al undepleted komatiites the extensive nickel exploration database on the belt provides a unique opportunity to examine geochemical variations in the context of volcanological evolution within each of the six komatiitic units in the greenstone belt there is a transition from komatiites 18 28 wt mgo in the liquid to high and low magnesium komatiitic basalts 5 18 wt mgo with stratigraphic height and much of the chemical variance within the komatiitic suite can be explained in terms of the addition or fractionation of olivine there are however aspects of the incompatible element signatures which must be attributed to other factors the more primitive komatiites from the lower ultramafic units are al depleted al2o3 tio2 10 5 13 0 and depleted in both light and heavy ree lasmn 0 5 gdybn 1 5 komatiites from the uppermost ultramafic units are variably less depleted in al al2o3tio2 16 5 20 5 this is interpreted to reflect decreasing retention of garnet in the source region of the forrestania komatiites over time and possibly a decrease in the depth of melting within the al depleted suite there are also anomalous enrichments in sio2 feo tio2 and zr which correlate with regional variations in the composition of substrate metasedimentary rocks banded iron formation versus felsic tuff coupled with field evidence for trough structures at the base of lava channel sequences these chemical anomalies provide strong evidence for supracrustal thermal erosion by komatiite lavas the forrestania data indicate that 2 9 ga old komatiites were generated over a range of melting conditions spanning those typical of older and younger archaean sequences and that contamination by supracrustal thermal erosion can influence komatiite chemistry on a regional scale