thermal state of the taranaki basin new zealand the taranaki basin is an active margin basin that has been significantly affected by miocene subduction tectonics along the pacific australian plate boundary we have analyzed its present day thermal state using 354 bottom hole temperatures bhts from 115 wells distributed throughout the basin the measured temperatures were corrected using an exact solution to bullard s equation rather than the horner approximation thereby allowing for recovery dependence on well diameter and correction for some bhts at early time after circulation had ceased thermal conductivity measurements were completed on 256 samples from eight wells and matrix conductivities were determined for six end member lithologies by inversion formation conductivities are based on the conductivity and relative proportion of each end member component corrected bhts in situ thermal conductivity and estimates of sediment heat production were combined to compute the present day steady state heat flow the average heat flow is 60 mw m 2 but important geographic variations are present heat flow on the western platform is remarkably consistent at 53 60 mw m 2 attesting to its relative stability since the late cretaceous heat flow in the southern part of the basin is 65 70 mw m 2 due to as much as 3 km of late miocene erosion on the southern onshore and to the south of the peninsula heat flow is 50 3 mw m 2 possibly due to the heat sink effects of crustal thickening heat flow is highest at 74 mw m 2 on the northern peninsula adjacent to the taranaki volcanic zone suggesting a causal relationship between quaternary volcanism and high heat flow

the blanketing effect of sediments in basins formed by extension a numerical model application to the gulf of lion and viking graben abstract a numerical finite difference model is employed to reconstruct the time temperature history of sediments in basins formed by extension in which crustal thinning by stretching as well as the effects associated with sedimentation and compaction are taken into account two extreme cases of basins were investigated to identify the scale of this mechanism the gulf of lion illustrates a case of a young basin in which the average sedimentation rate is high 620 m ma and the viking graben in the north sea offers a case of a basin formed in the triassic but where average sedimentation rate is much less 37 m ma in the former the sediments absorb 30 of the surface heat flow while in the latter the effect is only 10

spectral mixture modeling a new analysis of rock and soil types at the viking lander 1 site a viking lander 1 image was modeled as mixtures of reflectance spectra of palagonite dust gray andesitelike rock and a coarse rocklike soil the rocks are covered to varying degrees by dust but otherwise appear unweathered rocklike soil occurs as lag deposits in deflation zones around stones and on top of a drift and as a layer in a trench dug by the lander this soil probably is derived from the rocks by wind abrasion and or spallation dust is the major component of the soil and covers most of the surface the dust is unrelated spectrally to the rock but is equivalent to the global scale dust observed telescopically a new method was developed to model a multispectral image as mixtures of end member spectra and to compare image spectra directly with laboratory reference spectra the method for the first time uses shade and secondary illumination effects as spectral end members thus the effects of topography and illumination on all scales can be isolated or removed the image was calibrated absolutely from the laboratory spectra in close agreement with direct calibrations the method has broad applications to interpreting multispectral images including satellite images

veneers rinds and fracture fills relatively late alteration of sedimentary rocks at meridiani planum mars veneers and thicker rinds that coat outcrop surfaces and partially cemented fracture fills formed perpendicular to bedding document relatively late stage alteration of ancient sedimentary rocks at meridiani planum mars the chemistry of submillimeter thick buff colored veneers reflects multiple processes at work since the establishment of the current plains surface veneer composition is dominated by the mixing of silicate rich dust and sulfate rich outcrop surface but it has also been influenced by mineral precipitation including nacl and possibly by limited physical or chemical weathering of sulfate minerals competing processes of chemical alteration perhaps mediated by thin films of water or water vapor beneath blanketing soils and sandblasting of exposed outcrop surfaces determine the current distribution of veneers dark toned rinds several millimeters thick reflect more extensive surface alteration but also indicate combined dust admixture halite precipitation and possible minor sulfate removal cemented fracture fills that are differentially resistant to erosion occur along the margins of linear fracture systems possibly related to impact these appear to reflect limited groundwater activity along the margins of fractures cementing mechanically introduced fill derived principally from outcrop rocks the limited thickness and spatial distribution of these three features suggest that aqueous activity has been rare and transient or has operated at exceedingly low rates during the protracted interval since outcropping meridiani strata were exposed on the plains surface

bottom hole temperature stabilization with continued circulation of drilling mud determination of true formation temperature from measured bottom hole temperature bht is important for well log interpretation and geothermal studies especially with the current realization of the role of temperature in hydrocarbon maturation a bulk thermal diffusivity of the borehole rock system of approximately 0 003cm2 sec initially suggested by leblanc et al 1982 is confirmed by comparison with a two media borehole model in general time consecutive bht measurements exhibit slower stabilization than those predicted by thermal conduction models a simple model of thermal stabilization of a borehole with continued circulation after cessation of drilling is proposed by modeling the thermal sink due to continued circulation of drilling mud as an exponentially decaying sink thermal stabilization curves more consistent with observation are obtained a good estimate of true formation temperature can be obtained by a curve matching technique where the observed bht data are well behaved and the ph

optical scattering properties of terrestrial varnished basalts compared with rocks and soils at the viking lander sites basalt flows at the pisgah volcanic field california are mantled by aeolian silt sized deposits the bright mantle is overlain by a dense pavement of basalt cobbles smoothed by aeolian abrasion and coated with glossy dark gray and red desert varnishes in contrast the two viking landing sites on mars lack desert pavements and rocks have glossy surfaces that in some cases are brighter than soils to pursue further the scattering characteristics of varnished basalt cobbles for comparison to mars rocks laboratory measurements of bidirectional reflectance 0 69 m center wavelength were made as a function of incidence and emission angle along the principal plane for varnished and fresh basalt surfaces the reflectance data fit with a scattering model that includes specular reflections from rough surfaces and volume penetration and reflection show that the red varnished surfaces have higher single scattering albedoes and higher surface roughness values than the dark gray varnished surfaces 0 56 and 0 42 21 and 17 respectively fresh cut surfaces have lowest values 0 40 and 6 results are consistent with observations made from thin sections for these surfaces and with field observations that show dark gray varnished surfaces are smoothed by exposure to wind abrasion dark red varnished surfaces tend to be rougher because they are embedded in the aeolian mantle and develop in a protected environment application of the model to atmospherically corrected radiometrically calibrated viking lander images 0 60 to 0 74 m shows that many rocks are smoother and have single scattering albedoes higher than soils 9 versus 27 0 71 versus 0 63 respectively results are consistent with a model in which rocks at the surface of mars become smoothed by aeolian abrasion and coated with atmospheric dust lack of desert pavement on mars is probably associated with a scarcity of cobbles and a lack of soil forming processes similar bright smooth coatings are expected at other locations on mars including the pathfinder ares vallis site

the martian surface as imaged sampled and analyzed by the viking landers the two viking landers touched down on the surface of mars in july and september of 1976 viking lander 1 renamed the mutch memorial station mms continued to operate for 3 martian years in chryse planitia the landing site is a rolling sparsely cratered plain impact crater size frequency distributions demonstrate that only meters of vertical erosion have occurred over the lifetime of the surface the site exhibits bedrock exposures numerous rocks excavated during cratering events indurated fine grained sediment blocky material mixed with dust and lithic fragments and aeolian drifts that overlie the blocky material and which probably accumulated during global dust storms lander 2 operated for approximately 2 martian years in utopia planitia a region subjected to volcanic impact aeolian and periglacial phenomena lander 2 is located west of the 100 km diameter crater mie on or near the distal end of the continuous ejecta deposits polygonal ground suggests that desiccation or freeze thaw processes have occurred the lander 2 site exhibits numerous rocks excavated from craters and exposed by erosion set in a matrix of crusty to cloddy sediment rare aeolian drifts overlie the crusty to cloddy material lander multispectral imaging of sediment exposures at both sites is best matched with iron rich claylike weathering products called palagonites the spectral characteristics are probably governed by thin deposits of dust from global and local dust storms darkest rocks have reflectance values that match iron rich igneous rocks although most rocks are covered with indurated coatings of the palagonitelike products chemical compositions of sediments at the two landing sites are strikingly similar suggesting an aeolian origin the compositions suggest an iron rich igneous source rock and are matched by an assemblage of clays and salts samples of blocky materials were found to have about 50 more cl and so3 than other samples implying cementation by salts the magnetic component in the sediment is silt sized or finer and may be maghemite or ultrafine grained hematite no indigenous organic compounds were found the materials were found to be highly reactive releasing o2 when h2o was added oxidizing organic nutrients on board the landers and fixing atmospheric co2 clay to silt sized particles were inferred for drift and crusty to cloddy materials no terrestrial samples have been found that replicate all the attributes of the viking samples approximately 10 m of h2o ice accumulated during both winters at lander 2 and each time evaporated over approximately 200 martian days thin layers of bright red dust from global and local dust storms accumulated at both sites during the first 2 martian years during the third winter strong winds generally scoured the mms site leaving behind a darker aeolian lag deposit bedrock at both sites formed billions of years ago and rocks have been generated and weathered slowly over geologic time but aeolian sediments accumulate become cemented and are subsequently eroded over time spans of millions of years or less the lifetime of the sedimentary deposits at the landing sites may be governed by the 105 to 106 year variations in climate due to quasi periodic changes in obliquity eccentricity and spin axis orientation

chromaticity of the martian sky as observed by the mars exploration rover pancam instruments 1 we have derived quantitative color estimates of the martian sky from data acquired by the panoramic cameras pancams on the mars exploration rovers spirit and opportunity we calculate the perceptual color of the sky directly from the absolute radiometric calibration of the cameras following similar approaches to those used in previous studies with viking lander and mars pathfinder data we further use these measurements to study changes in sky color throughout the mer missions and to compare these to changes in atmospheric opacity determined from direct solar imaging by the pancams we have derived a functional relationship between sky color and optical depth and discuss its possible uses and limitations finally we simulate changes in sky color as suspended dust is removed and present visual representations of these based on modeling results past studies and observed mer sky brightnesses the color of the martian sky as opacity decreases from 1 0 to 0 0 is estimated to change from dark yellowish brown at high opacity to bluish black or black if dust free

the thermal regime of south african continental margins abstract we present thermal data from 100 oil exploration boreholes on the continental margins of south africa near surface temperature profiles are constrained with temperatures acquired during reservoir tests corrected bottom hole temperatures and seafloor temperatures the thermal conductivity profiles are estimated from geophysical well logs using a neural network method available data allow us to determine 41 new heat flow values computed from depth ranges greater than 1000 m located on the western and southern continental margins of south africa we believe that the variations in surface heat flow are not controlled by the contribution of the sediments or the basement but rather by the mantle heat flow an upper bound of 30 mw m 2 for the mantle heat flow on the interior of the continent can be inferred from the lowest available estimates located near the coastline on the southern continental margin on both continental margins heat flow values reach a maximum of about 60 mw m 2 100 km away from the shore and consistently decrease further away towards values typically encountered in old oceanic domains 50 mw m 2 this indicates that 1 the mantle heat flow increases over a short distance at the edge of the continent which is consistent with studies on the effect of continents on mantle convection and 2 it may increase to a value greater than heat flow on the adjacent ocean as a possible consequence of the effect of the transition between thin oceanic lithosphere and thick and cold continental lithosphere on mantle convection

low abundance materials at the mars pathfinder landing site an investigation using spectral mixture analysis and related techniques abstract recalibrated and geometrically registered multispectral images from the imager for mars pathfinder imp were analyzed using spectral mixture analysis sma and related techniques sma models a multispectral image scene as a linear combination of endmember spectra and anomalous materials which do not fit the model are detected as model residuals while most of the imp data studied here are modeled generally well using bright dust gray rock and shade image endmembers additional anomalous materials were detected through careful analysis of root mean square rms error images resulting from sma for example analysis of sma fraction and rms images indicates spectral differences within a previously monolithologic dark soil class a type of dark soil that has high fractional abundances in rock fraction images gray rock soil was identified other anomalous materials identified included a previously noted black rock lithology a class of possibly indurated compacted or partially cemented soils intermediate soil and a unit referred to as anomalous patches on at least one rock the black rock lithology has a strong 900 1000 nm absorption and modeling of the derived image endmembers using a laboratory reference endmember modeling rem approach produced best fit model spectra that are most consistent with the presence of high ca pyroxenes and or olivine crystalline ferric oxide minerals or mixtures of these materials as important components of the black rock endmember more unique mineralogic identifications could not be obtained using our initial rem analyses both intermediate soil and anomalous patches units exhibit a relatively narrow 860 950 nm absorption that is consistent with the presence of either low ca pyroxenes or a cementing crystalline ferric oxide mineral

hematite spherules at meridiani results from mi mini tes and pancam 1 we report on observations of hematite bearing spherules at meridiani planum made using the microscopic imager mi mini thermal emission spectrometer mini tes and panoramic camera pancam instruments on the mars exploration rover opportunity spherules were observed on soil surfaces and in outcrop rocks both on undisturbed surfaces and in abraded surfaces ground using the rock abrasion tool rat spherule size and shape change little along the 850 m eastward traverse from eagle crater to endurance crater but spherules decrease and then slightly increase in size along the 6 km traverse from endurance south to victoria crater local populations range from submillimeters to several millimeters in diameter an additional small diameter 100 m size population is possible an increase in irregular shapes is found near victoria crater this combined with the size decrease south of endurance suggests either a changing depositional environment or variation in the duration and timing of diagenetic events the dominant smaller size population observed early in the mission in aeolian areas and ripple crests is observed as the primary size population in abraded outcrop farther south this suggests that successively younger beds are exposed at the surface along the southward traverse stratigraphically higher units removed by erosion could be recorded by the present surface lag deposit coordinated systematic observations are used to determine optical and infrared hematite indices of the surface soils in pancam and mini tes in spite of the systematic variation seen in mi both pancam and mini tes indices are highly variable based on the local surface and neither show systematic trends south of endurance the lack of a 390 cm 1 feature in mini tes spectra suggests concentric or radial interior structure within the spherules at scales too fine for mi to observe mini tes does not detect any silicate component in the spherules a bound water component in soils or in exchange with the atmosphere is observed these spherules have been previously interpreted as concretions formed within what were once water saturated diagenetically altered dirty evaporate sandstone sediments our observations support this interpretation however no single terrestrial analog provides a model that can account for all attributes of the spherules on mars

on the spectral reflectance properties of materials exposed at the viking landing sites bidirectional reflectances calibrated to within 10 uncertainties for blue 0 40 0 52 m green 0 50 0 59 m and red 0 60 0 74 m channels were determined for 31 block and soil exposures imaged by the viking lander cameras reflectances were corrected for atmospheric attenuation by using optical depth measurements obtained by the lander cameras and for skylight illumination by subtracting the brightness values of adjacent shadowed areas reflectances for two facets on each of two large blocks were computed for a common geometry by determining facet orientations from high resolution lander stereo images and by fitting the hapke irvine photometric function to reflectances estimated for several geometries results indicate that individual facets on the same block have different optical properties the darkest grayest block facets have properties similar to laboratory reflectance spectra of mafic rocks that are thinly coated with ferric iron rich palagonite most block surfaces have reflectances consistent with thin to optically thick covers of palagonitic material limited exposures of soil have spectra that are also similar to palagonitic material the majority of the soils sampled and a few block surfaces have spectra with steeper slopes and greater spectral curvatures than the palagonite analog consistent with greater degree of ferric iron crystallinity the soils could be an intimate mixture of palagonitic material and other materials not seen in end member form but if so these other materials would need an even greater slope and curvature than observed soils the differences in reflectance properties for common block surfaces compared to common soils imply that local weathering of blocks has not contributed significantly to the soil exposed at the landing sites

digital isochrons of the world s ocean floor we have created a digital age grid of the ocean floor with a grid node interval of 6 arc min using a self consistent set of global isochrons and associated plate reconstruction poles the age at each grid node was determined by linear interpolation between adjacent isochrons in the direction of spreading ages for ocean floor between the oldest identified magnetic anomalies and continental crust were interpolated by estimating the ages of passive continental margin segments from geological data and published plate models we have constructed an age grid with error estimates for each grid cell as a function of 1 the error of ocean floor ages identified from magnetic anomalies along ship tracks and the age of the corresponding grid cells in our age grid 2 the distance of a given grid cell to the nearest magnetic anomaly identification and 3 the gradient of the age grid i e larger errors are associated with high age gradients at fracture zones or other age discontinuities future applications of this digital grid include studies of the thermal and elastic structure of the lithosphere the heat loss of the earth ridge push forces through time asymmetry of spreading and providing constraints for seismic tomography and mantle convection models

a crustal transect between precambrian australia and the timor trough across the vulcan sub basin abstract wide angle seismic data from ocean bottom seismographs together with gravity and deep marine reflection profiling data along the vulcan transect in northern australia define the crustal scale features between the precambrian australian craton and the timor trough the transect provides an outline of crustal and upper mantle architecture across the major boundary between the australian and se asian plates when linked with earlier deep marine seismic profiling near the australian coast relatively unaltered precambrian kimberley basin rocks are inferred to extend to the edge of a shallow water shelf area yampi shelf with a crustal thickness of 35 km the crust then thins to 26 km under the outer shelf near the timor trough over the same distance palaeozoic mesozoic basin sequences are interpreted to thicken to 12 13 km inferring an attenuation of precambrian basement rocks from 35 to 13 14 km across the margin 2 6 on the outer shelf the vulcan sub basin is a trans tensional rift within permo triassic platform areas ashmore platform londonderry high within the lower crust under major bounding faults at the sub basin platform margins there are elevated p wave velocities to 7 km s suggesting emplacement of intrusive more mafic rocks at depth during basin forming processes at mid crustal levels near the top of the inferred attenuated precambrian crustal rocks there are strong near vertical incidence reflections at about 13 km depth that are interpreted to be a detachment or further evidence of intrusive rocks additionally seismic energy reflected at wide angles from within the upper mantle at 38 45 km depth indicates that compositional boundaries heterogeneities continue at depth detailed information within the basin sediments includes the interpretation of crosscutting velocity patterns within the mesozoic sequences as an indication of decreasing porosity with depth of burial and the presence of a low velocity sequence at 1 2 km depth across the londonderry high

spectral evidence for the mineralogy of high albedo soils and dust on mars because of the lack of direct mineralogic data available for mars spectral remote sensing techniques and in particular earth based reflectance spectroscopy remain the primary source of this information presented here are laboratory observations which further constrain the mineralogy and origin of the high albedo soils and dust earth based observations show the reflectance spectra of classical bright regions to be fairly uniform with a strong fe3 o2 charge transfer absorption edge extending from the near uv through the visible this absorption is relatively smooth unlike those observed for crystalline ferric oxides which have superimposed fe3 crystal field bands dilution of ferric oxide with a spectrally more neutral medium montmorillonite weakens the charge transfer and crystal field absorptions together and does not serve to make the ferric oxide spectrum more mars like smoother nontronite ferric iron bearing smectite clay was also investigated for spectral agreement with telescopic observations pure nontronite has fe3 absorptions analogous to but different from ferric oxides as in the previous case the absorptions are very distinct and inappropriate for mars admixture of neither montmorillonite nor ferric oxide serves to improve the nontronite spectrum the conclusion is that nontronite is not a major component of martian soils although the presence of other iron poor clays cannot be totally excluded based on currently available observational data the best spectral analogs known for high albedo soil and dust are a specific type of palagonite from hawaii x ray amorphous weathering products of mafic volcanic glass the indication is therefore that ferric iron on mars is likely to occur in poorly defined crystallo graphic sites such as found in these amorphous materials these materials form slowly under semiarid conditions at ambient temperature even low temperature hydrothermal alteration of glass might provide enough ion mobility to favor some formation of crystalline clays over amorphous gels and may therefore not be the primary mechanism responsible for soil formation on mars the amorphous hawaiian soils exist metastably for thousands of years on earth similar materials on mars would be expected to survive considerably longer under the present cold and dry climatic conditions

using neural networks to predict thermal conductivity from geophysical well logs summary we present a new approach based on neural networks to predict the thermal conductivity of sedimentary rocks from a set of geophysical well logs this method is calibrated on ocean drilling program odp data which provide several thousands of conductivity measurements combined with five geophysical well logs sonic density neutron porosity resistivity and gamma ray this data set is used to train multilayer perceptrons mlp and to find an empirical relationship between well logs mlp inputs and thermal conductivity mlp output validation tests suggest that mlp provide better estimates of thermal conductivity within 15 per cent confidence level than classical linear models and still give satisfying results with sets of only four well logs if neutron porosity is included in two odp sites 863b and 1109d mlp s predictions are compared to conventional mixing methods although this latter technique gives reliable results provided that rocks description is precise enough the mlp is more straightforward does not need any extra parameter and makes predictions in good agreement with the experimental trends this method will be useful in the estimation of heat flow from data acquired in scientific and industrial boreholes

athena microscopic imager investigation 1 the athena science payload on the mars exploration rovers mer includes the microscopic imager mi the mi is a fixed focus camera mounted on the end of an extendable instrument arm the instrument deployment device idd the mi was designed to acquire images at a spatial resolution of 30 microns pixel over a broad spectral range 400 700 nm the mi uses the same electronics design as the other mer cameras but has optics that yield a field of view of 31 31 mm across a 1024 1024 pixel ccd image the mi acquires images using only solar or skylight illumination of the target surface a contact sensor is used to place the mi slightly closer to the target surface than its best focus distance about 66 mm allowing concave surfaces to be imaged in good focus coarse focusing 2 mm precision is achieved by moving the idd away from a rock target after the contact sensor has been activated the mi optics are protected from the martian environment by a retractable dust cover the dust cover includes a kapton window that is tinted orange to restrict the spectral bandpass to 500 700 nm allowing color information to be obtained by taking images with the dust cover open and closed mi data will be used to place other mer instrument data in context and to aid in petrologic and geologic interpretations of rocks and soils on mars

preliminary results on photometric properties of materials at the sagan memorial station mars reflectance measurements of selected rocks and soils over a wide range of illumination geometries obtained by the imager for mars pathfinder imp camera provide constraints on interpretations of the physical and mineralogical nature of geologic materials at the landing site the data sets consist of 1 three small photometric spot subframed scenes covering phase angles from 20 to 150 2 two image strips composed of three subframed images each located along the antisunrise and antisunset lines photometric equator covering phase angles from 0 to 155 and 3 full image scenes of the rock yogi covering phase angles from 48 to 100 phase functions extracted from calibrated data exhibit a dominantly backscattering photometric function consistent with the results from the viking lander cameras however forward scattering behavior does appear at phase angles 140 particularly for the darker gray rock surfaces preliminary efforts using a hapke scattering model are useful in comparing surface properties of different rock and soil types but are not well constrained possibly due to the incomplete phase angle availability uncertainties related to the photometric function of the calibration targets and or the competing effects of diffuse and direct lighting preliminary interpretations of the derived hapke parameters suggest that 1 red rocks can be modeled as a mixture of gray rocks with a coating of bright and dark soil or dust and 2 gray rocks have macroscopically smoother surfaces composed of microscopically homogeneous clear materials with little internal scattering which may imply a glass like or varnished surface

diverse lithologies and alteration events on the rim of noachian aged endeavour crater meridiani planum mars in situ compositional evidence we report the results of geological studies by the opportunity mars rover on the endeavour crater rim four major units occur in the region oldest to youngest the matijevic shoemaker grasberg and burns formations the matijevic formation consisting of fine grained clastic sediments is the only pre endeavour impact unit and might be part of the noachian etched units of meridiani planum the shoemaker formation is a heterogeneous polymict impact breccia its lowermost member incorporates material eroded from the underlying matijevic formation the shoemaker formation is a close analog to the bunte breccia of the ries crater although the average clast sizes are substantially larger in the latter the grasberg formation is a thin fine grained homogeneous sediment unconformably overlying the shoemaker formation and likely formed as an airfall deposit of unknown areal extent the burns formation sandstone overlies the grasberg but compositions of the two units are distinct there is no evidence that the grasberg formation is a fine grained subfacies of the burns formation the rocks along the endeavour crater rim were affected by at least four episodes of alteration in the noachian and early hesperian i vein formation and alteration of preimpact matijevic formation rocks ii low water rock alteration along the disconformity between the matijevic and shoemaker formations iii alteration of the shoemaker formation along fracture zones and iv differential mobilization of fe and mn and caso 4 vein formation in the grasberg and shoemaker formations episodes ii and iii possibly occurred together but i and iv are distinct from either of these

the mars pathfinder mission mars pathfinder one of the first discovery class missions quick low cost projects with focused science objectives will land a single spacecraft with a microrover and several instruments on the surface of mars in 1997 pathfinder will be the first mission to use a rover carrying a chemical analysis instrument to characterize the rocks and soils in a landing area over hundreds of square meters on mars which will provide a calibration point or ground truth for orbital remote sensing observations in addition to the rover which also performs a number of technology experiments pathfinder carries three science instruments a stereoscopic imager with spectral filters on an extendable mast an alpha proton x ray spectrometer and an atmospheric structure instrument meteorology package the instruments the rover technology experiments and the telemetry system will allow investigations of the surface morphology and geology at submeter to a hundred meters scale the petrology and geochemistry of rocks and soils the magnetic properties of dust soil mechanics and properties a variety of atmospheric investigations and the rotational and orbital dynamics of mars landing downstream from the mouth of a giant catastrophic outflow channel ares vallis at 19 5 n 32 8 w offers the potential of identifying and analyzing a wide variety of crustal materials from the ancient heavily cratered terrain intermediate aged ridged plains and reworked channel deposits thus allowing first order scientific investigations of the early differentiation and evolution of the crust the development of weathering products and the early environments and conditions on mars

a transect across australia s southern margin in the otway basin region crustal architecture and the nature of rifting from wide angle seismic profiling abstract the otway basin in southeastern australia formed on a triangular shaped area of extended continental lithosphere during two extensional episodes in cretaceous to miocene times which ultimately led to the separation of australia and antarctica the velocity structure and crustal architecture of the otway continental margin has been interpreted from offshore onshore wide angle seismic profiling data along a transect extending from near the northern otway basin margin with palaeozoic outcrop to the deep ocean basin under the southern ocean along this transect the otway continental margin ocm transect the onshore half graben geometry of early cretaceous deposition gives way to a 5 km thick basin sequence p wave velocity 2 2 4 6 km s extending down the continental slope offshore to at least 60 km from the shoreline at 120 km from the nearest shore sonobuoy data indicate a 4 5 km sedimentary sequence overlying 7 km of crustal basement rocks above the moho at 15 km depth water depth 4220 m conspicuous strong moho reflections are evident under the continental slope at about 10 2 s twt basement is interpreted to be attenuated faulted palaeozoic rocks of the delamerian and lachlan orogens intruded with jurassic volcanics that thin from 16 km onshore to about 3 5 km at 120 km from the nearest shore these rocks comprise a 3 km section that has a velocity of 5 5 5 7 km s overlying deeper basement with a velocity of 6 15 6 35 km s over the same distance the moho shallows from a depth of 30 km onshore to 15 km depth at 120 km from the nearest shore and then to about 12 km in the deep ocean at the limits of the profile water depth 5200 m the continent ocean boundary cob is interpreted to be at a prominent topographic inflection point at the bottom of the continental slope in 4800 m of water p wave velocities in the lower crust are 6 4 6 8 km s above a transition to the moho with an upper mantle velocity of 8 05 km s there is no evidence of massive high velocity 7 km s intrusives underplate material in the lower crust nor any syn rift or early post rift subaerial volcanics indicating that the otway continental margin can be considered a non volcanic margin similar in many respects to some parts of the atlantic ocean margins e g the nova scotia newfoundland margin off canada and the galicia bank off the iberian peninsula

the imager for mars pathfinder experiment the imager for mars pathfinder imp a stereoscopic multispectral camera is described in terms of its capabilities for studying the martian environment the camera s two eyes separated by 15 0 cm provide the camera with range finding ability each eye illuminates half of a single ccd detector with a field of view of 14 4 14 0 and has 12 selectable filters the 18 optics have a large depth of field and no focussing mechanism is required a mechanical shutter is avoided by using the frame transfer capability of the 512 512 ccd the resolving power of the camera 0 98 mrad pixel is approximately the same as the viking lander cameras however the signal to noise ratio for imp greatly exceeds viking approaching 350 this feature along with the stable calibration of the filters between 440 and 1000 nm distinguishes imp from viking specially designed targets are positioned on the lander they provide information on the magnetic properties of wind blown dust measure the wind vectors and provide radiometric standard reflectors for calibration also eight low transmission filters are included for imaging the sun directly at multiple wavelengths giving imp the ability to measure dust opacity and potentially the water vapor content several experiments beyond the requisite color panorama are described in detail contour mapping of the local terrain multispectral imaging of the surrounding rock and soil to study local mineralogy viewing of three wind socks measuring atmospheric opacity and water vapor content and estimating the magnetic properties of wind blown dust this paper is intended to serve as a guide to understanding the scientific integrity of the imp data that will be returned from mars starting on july 4 1997

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

bounce rock a shergottite like basalt encountered at meridiani planum mars additional co authors thanasis economou steven p gorevan brian c hahn gostar klingelhofer timothy j mccoy harry y mcsween jr douglas w ming richard v morris daniel s rodionov steven w squyres heinrich wanke shawn p wright michael b wyatt albert s yen

soil like deposits observed by sojourner the pathfinder rover most of the soil like materials at the pathfinder landing site behave like moderately dense soils on earth with friction angles near 34 39 and are called cloddy deposits cloddy deposits appear to be poorly sorted with dust sized to granule sized mineral or rock grains they may contain pebbles small rock fragments and clods thin deposits of porous compressible drifts with friction angles near 26 28 are also present drifts are fine grained cohesions of both types of deposits are small there may be indurated soil like deposits and or coated or crusted rocks cloddy deposits may be fluvial sediments of the ares tiu floods but other origins such as ejecta from nearby impact craters should be considered drifts are probably dusts that settled from the martian atmosphere remote sensing signatures of the deposits inferred from rover observations are consistent with those observed from orbit and earth

alteration processes in volcanic soils and identification of exobiologically important weathering products on mars using remote sensing determining the mineralogy of the martian surface material provides information about the past and present environments on mars which are an integral aspect of whether or not mars was suitable for the origin of life mineral identification on mars will most likely be achieved through visible infrared remote sensing in combination with other analyses on landed missions therefore understanding the visible and infrared spectral properties of terrestrial samples formed via processes similar to those thought to have occurred on mars is essential to this effort and will facilitate site selection for future exobiology missions to mars visible to infrared reflectance spectra are presented here for the fine grained fractions of altered tephra lava from the haleakala summit basin on maui the tarawera volcanic complex on the northern island of new zealand and the greek santorini island group these samples exhibit a range of chemical and mineralogical compositions where the primary minerals typically include plagioclase pyroxene hematite and magnetite the kind and abundance of weathering products varied substantially for these three sites due in part to the climate and weathering environment the moist environments at santorini and tarawera are more consistent with postulated past environments on mars while the dry climate at the top of haleakala is more consistent with the current martian environment weathering of these tephra is evaluated by assessing changes in the leachable and immobile elements and through detection of phyllosilicates and iron oxide oxyhydroxide minerals identifying regions on mars where phyllosilicates and many kinds of iron oxides oxyhydroxides are present would imply the presence of water during alteration of the surface material tephra samples altered in the vicinity of cinder cones and steam vents contain higher abundances of phyllosilicates iron oxides and sulfates and may be interesting sites for exobiology

overview of the mars pathfinder mission launch through landing surface operations data sets and science results mars pathfinder successfully landed at ares vallis on july 4 1997 deployed and navigated a small rover about 100 m clockwise around the lander and collected data from three science instruments and ten technology experiments the mission operated for three months and returned 2 3 gbits of data including over 16 500 lander and 550 rover images 16 chemical analyses of rocks and soil and 8 5 million individual temperature pressure and wind measurements path finder is the best known location on mars having been clearly identified with respect to other features on the surface by correlating five prominent horizon features and two small craters in lander images with those in high resolution orbiter images and in inertial space from two way ranging and doppler tracking tracking of the lander has fixed the spin pole of mars determined the precession rate since viking 20 years ago and indicates a polar moment of inertia which constrains a central metallic core to be between 1300 and 2000 km in radius dark rocks appear to be high in silica and geochemically similar to anorogenic andesites lighter rocks are richer in sulfur and lower in silica consistent with being coated with various amounts of dust rover and lander images show rocks with a variety of morphologies fabrics and textures suggesting a variety of rock types are present rounded pebbles and cobbles on the surface as well as rounded bumps and pits on some rocks indicate these rocks may be conglomerates although other explanations are also possible which almost definitely require liquid water to form and a warmer and wetter past air borne dust is composed of composite silicate particles with a small fraction of a highly magnetic mineral interpreted to be most likely maghemite explanations suggest iron was dissolved from crustal materials during an active hydrologic cycle with maghemite freeze dried onto silicate dust grains remote sensing data at a scale of a kilometer or greater and an earth analog correctly predicted a rocky plain safe for landing and roving with a variety of rocks deposited by catstrophic floods which are relatively dust free the surface appears to have changed little since it formed billions of years ago with the exception that eolian activity may have deflated the surface by 3 7 cm sculpted wind tails collected sand into dunes and eroded ventifacts fluted and grooved rocks pathfinder found a dusty lower atmosphere early morning water ice clouds and morning near surface air temperatures that changed abruptly with time and height small scale vortices interpreted to be dust devils were observed repeatedly in the afternoon by the meteorology instruments and have been imaged

results from the mars pathfinder camera images of the martian surface returned by the imager for mars pathfinder imp show a complex surface of ridges and troughs covered by rocks that have been transported and modified by fluvial aeolian and impact processes analysis of the spectral signatures in the scene at 440 to 1000 nanometer wavelength reveal three types of rock and four classes of soil upward looking imp images of the predawn sky show thin bluish clouds that probably represent water ice forming on local atmospheric haze opacity 0 5 haze particles are about 1 micrometer in radius and the water vapor column abundance is about 10 precipitable micrometers

heat flow in the western mediterranean thermal anomalies on the margins the seafloor and the transfer zones the western mediterranean basin has been formed by miocene back arc extension and is underlain by a thin and young lithosphere this young lithosphere is warm as testified by an overall elevated offshore heat flow heat flow within the western mediterranean is however highly variable and existing data are unevenly distributed and poorly studied in the central part of the liguro provencal and algero balearic basins this central part is floored by a young oceanic crust bordered by different continental margins cut by transform faults and filled by up to 8 km of sediments we present a total of 148 new heat flow data collected during the medsalt and westmedflux cruises in 2015 and 2016 and aligned along seven regional profiles that show an important heat flow variability on the basin scale but also locally on the margins a new heat flow map for the western mediterranean outlines the following regional features 1 a higher average heat flow in the algero balearic basin compared to the liguro provencal basin 94 13 mw m2 and 78 16 mw m2 respectively and 2 a regional thermal asymmetry in both basins but with opposed heat flow trends up to 20 of this heat flow difference can be explained by sediment blanketing but age and heterogeneity of ocean crust due to an asymmetric and polyphased opening of the basins are believed to have given the major thermal imprint estimates of the age of the oceanic crust based on the new heat flow suggest a considerably younger west algerian basin 16 23 ma compared to the east algerian basin and the west sardinia oceanic floor 31 37 ma on the margins and ocean continent transitions of the western mediterranean the new heat flow data point out the existence of two types of local anomalies length scale 5 30 km 1 locally increased heat flow up to 153 mw m2 on the gulf of lion margin results from thermal refraction of large salt diapirs and 2 the co existing of both low 110 mw m2 heat flow areas on the south balearic margin suggests a heat redistribution system we suspect the lateral heat advection is resulting from a regional fluid circulation in the sediments associated to the widespread plio pleistocene volcanism on the south balearic margin

late neogene exhumation patterns in taranaki basin new zealand evidence from offset porosity depth trends taranaki basin new zealand is located adjacent to the australian pacific plate boundary where the tectonic regime changes from dominantly subduction related to the north to transpression related along the alpine fault to the south during the neogene burial and exhumation varied extensively in both time and space in response to subsidence and uplift along this evolving plate boundary zone the basin can be divided into two regions 1 the western platform outside the plate boundary deformation zone where no uplift nor exhumation has occurred and 2 the eastern mobile belt which lies inside the deformation zone and has been variably uplifted and exhumed exhumation magnitudes for sedimentary deposits of the basin are estimated from offset porosity depth trends the analysis is based on correlating sonic log travel times with compensated density logs permitting sonic travel time to be used as a proxy for porosity twelve western platform wells are used to define a standard exponential porosity depth trend with an extrapolated surface porosity of 50 and an exponential decay factor of 2265 m valid for mudstone shale sections spanning a depth range of 300 3000 m this curve is a calibration curve against which offset porosity depth trends from wells in exhumed regions can be compared to determine apparent exhumation amounts porosity depth trends for 43 eastern mobile belt wells are offset 0 2800 m shallower relative to the western platform trend but generally are parallel to it in the southern region of the eastern mobile belt net exhumation amounts which are the sum of the porosity depth trend offset and depth to unconformity range from 850 to 3000 m most of this exhumation occurred on discrete contractional structures in late miocene to early pliocene time probably associated with an increased rate of convergence across the alpine fault system to the south in the eastern region of the eastern mobile belt net exhumation progressively increases from 0 m in the south to 1800 m in the northeast part of the basin consistent with the 2 4 sw structural tilt of onshore strata the regional and consistent pattern of exhumation in the eastern region contrasts with the discrete structure related exhumation in the southern region and is consistent with models of thermal and flexural uplift

the pathfinder microrover an exciting scientific component of the pathfinder mission is the rover which will act as a mini field geologist by providing us with access to samples for chemical analyses and close up images of the martian surface performing active experiments to modify the surface and study the results and exploring the landing site area

observational evidence of crystalline iron oxides on mars visible to near ir 0 4 1 0 mu m spectral reflectance observations of mars during the 1988 opposition were performed at mauna kea observatory using a circular variable filter spectrometer at a spectral resolution r lambda delta lambda approx 80 on august 13 and 14 1988 ut 41 regions 500 600 km in diameter were observed on mars the data have been reduced both to reflectance relative to solar analog mars 16 cyg b and to relative reflectance spot spot the spectra show the strong near uv reflectance dropoff characteristic of mars as well as absorptions at 0 62 0 72 mu m and 0 81 0 94 mu m both seen here clearly for the first time these absorption features are interpreted as fe sup 3 electronic transition bands that indicate the presence of crystalline ferric oxide or hydroxide minerals on the martian surface comparison of these data with laboratory spectra obtained by other workers supports the conclusion that a single iron oxide phase most likely hematite could account for all of the observed spectral behavior of the martian surface soils and airborne dust in the 0 4 1 0 mu m region this possibility must be reconciled with data from other possible spectral analogs and other wavelength regions as well as geochemical and mineral stability considerations to arrive at amore more complete understanding of the role of ferric minerals in martian surface mineralogy and weathering less

athena mars rover science investigation 1 each mars exploration rover carries an integrated suite of scientific instruments and tools called the athena science payload the primary objective of the athena science investigation is to explore two sites on the martian surface where water may once have been present and to assess past environmental conditions at those sites and their suitability for life the remote sensing portion of the payload uses a mast called the pancam mast assembly pma that provides pointing for two instruments the panoramic camera pancam and the miniature thermal emission spectrometer mini tes pancam provides high resolution color stereo imaging while mini tes provides spectral cubes at mid infrared wavelengths for in situ study a five degree of freedom arm called the instrument deployment device idd carries four more tools a microscopic imager mi for close up imaging an alpha particle x ray spectrometer apxs for elemental chemistry a mossbauer spectrometer mb for the mineralogy of fe bearing materials and a rock abrasion tool rat for removing dusty and weathered surfaces and exposing fresh rock underneath the payload also includes magnets that allow the instruments to study the composition of magnetic martian materials all of the athena instruments have undergone extensive calibration both individually and using a set of geologic reference materials that are being measured with all the instruments using a mer like rover and payload in a number of field settings we have devised operations processes that will enable us to use the mer rovers to formulate and test scientific hypotheses concerning past environmental conditions and habitability at the landing sites

lower crustal extension across the northern carnarvon basin australia evidence for an eastward dipping detachment asymmetry and strain partitioning along conjugate margins are often explained in terms of detachment faults nevertheless cogent evidence for their existence remains limited furthermore even when inferred detachment faults are imaged seismically it is difficult to demonstrate that differential displacement has occurred across these surfaces we present tectonic and stratigraphic evidence from the northern carnarvon basin northwest australia that documents the existence of an intracrustal eastward dipping detachment by integrating sequence stratigraphy with kinematic and isostatic models of basin development we conclude that the northern carnarvon basin was formed as a consequence of four extension events 1 a broadly distributed late permian event 2 a predominantly localized rhaetian event responsible for the inception of the barrow and dampier subbasins 3 a localized callovian fault reactivation within the barrow dampier subbasins and 4 a tithonian valanginian event that generated large post valanginian regional subsidence across the northern carnarvon basin with only minor accompanying brittle deformation and erosional truncation the regional distribution and amplitude of the post valanginian subsidence are not consistent with the minor amounts of tithonian valanginian brittle upper crustal extension observed on the margin large portions of the platform were emergent or at very shallow water depths prior to the tithonian valanginian extension to match the distribution and magnitude of the post valanginian thermal type subsidence requires significant lower crustal and mantle extension across the northern carnarvon basin such a distribution of extension implies the existence of an eastward dipping intracrustal detachment having a ramp flat ramp geometry that effectively thinned the lower crust and lithospheric mantle the detachment breached the surface close to the position of the continent ocean boundary west of the exmouth plateau the flat component of the detachment occurred at midcrustal depths 15 km across the plateau and ramped beneath the australian continent lower crustal ductile extension provides a viable mechanism to generate large regional subsidence with little attendant brittle deformation which may explain the paradox that both sides of many conjugate margins appear to be the upper plate

chemical compositions at mars landing sites subject to mars odyssey gamma ray spectrometer constraints 1 the mars odyssey gamma ray spectrometer grs is the first instrument suite to return elemental abundances throughout the midlatitudes of mars concentrations of cl fe h k si and th have been determined to tens of centimeter depths as mass fractions with reasonable confidence comparing such data with or normalizing them to in situ compositional data is difficult due to issues such as dramatic differences in spatial resolution difficulties in convolving densities abundances and compositions of different regolith components and a limited number of elements observed in common we address these concerns in the context of the grs using si at pathfinder to normalize remote data in addition we determine representative in situ compositions for spirit both with and without columbia hills rocks opportunity and viking 1 landing sites using grs derived h content to hydrate the soil component our estimate of the si mass fraction at pathfinder with 13 areal fraction of rocks is 21 the composition of major elements such as si and fe is similar across the four landing sites while minor elements show significant variability areal dominance of soil at all four landing sites causes representative compositions to be driven by the soil component while proportionally large uncertainties of bulk densities dominate the net uncertainties grs compositional determinations compare favorably with the in situ estimates for cl and k and for si by virtue of the normalization however the grs determined fe content at each landing site is consistently higher than the in situ value

a simple method to determine heat production from gamma ray logs abstract usually the radiogenic heat production is determined from the potassium k uranium u and thorium th content and the rock density by using the formula by rybach 1986 in boreholes the k u and th content can be taken from the natural gamma spectrometry tool ngs measurements and the rock density from the litho density tool ldt measurements in this paper a simple method is presented to determine heat production from normal gamma ray logs which are readily available from a vast number of boreholes this method is based on a linear relationship between the gamma ray gr and the heat production a for a wide variety of lithologies extending from granite through gneiss carbonate and amphibolite to basaltic rocks it is shown that this relation is valid in the range 0 350 api and 0 03 7 w m3 respectively with an error lower than 10 reliable information of the radiogenic heat production for the use in thermal modelling now can be derived quickly using only standard gr api readings

shear velocity structure of the northland peninsula new zealand inferred from ambient noise correlations 1 ambient noise correlation has been successfully applied in several cases to regions with dense seismic networks whose geometries are well suited to tomographic imaging the utility of ambient noise correlation based methods of seismic imaging where either network or noise field characteristics are less ideal has yet to be fully demonstrated in this study we focus on the northland peninsula of new zealand using data from five seismographs deployed in a linear pattern parallel to the direction from which most of the ambient noise arrives shear wave velocity profiles computed from rayleigh and love wave dispersion curves using the neighborhood algorithm are in good agreement with the results of a previous active source refraction experiment and a teleseismic receiver function and surface wave analysis in particular we compute a path averaged moho depth of 28 km along a 250 km profile the use of both rayleigh and love wave measurements enables us to estimate the degree of radial anisotropy in the crust yielding values of 2 15 these results demonstrate that ambient noise correlation methods provide useful geophysical constraints on lithospheric structure even for nonoptimal network geometries and noise field characteristics

the color of mars spectrophotometric measurements at the pathfinder landing site we calculate the color of the martian sky and surface directly using the absolute calibration of the mars pathfinder mpf lander camera which was observed to be stable during the mission the measured colors of the martian sky and surface at the pathfinder site are identical to the viking sites i e a predominantly yellowish brown color with only subtle variations these colors are distributed continuously and fall into five overlapping groups with distinct average colors and unique spatial characteristics shadowed soil soil soil rock mixtures rock and sky we report that the primary difference between the sky color and the color of the rocks is due to a difference in brightness measurements of the sky color show that the sky reddens away from the sun and toward the horizon and that the sky color varies with time of day and is reddest at local noon we present a true color picture of the martian surface and color enhancement techniques that increase image saturation maximize color discriminability while preserving hue and eliminate brightness variations while preserving the chromaticity of the scene although mars has long been called the red planet quantitative measurements of the surface color from telescopic and surface observations indicate a light to moderate yellowish brown color the pathfinder camera measurements presented here support the claim that the red planet is not red but indeed yellowish brown

morphology and texture of particles along the spirit rover traverse from sol 450 to sol 745 1 we quantified and classified the shape roundness size and texture of 935 loose surface particles along the spirit rover traverse from sols 450 745 to assess origin transport and other alteration mechanisms that altered particles during and after formation variation in particle morphologic parameters along traverse is consistent with crossing mapped geologic unit boundaries texture is divided into four types vesicular smooth and flat faceted rough and flat faceted and very rough sphericity and roundness are intermediate and low respectively comparable to particles moved by high energy transport or to crushed particles this indicates intermittent high energy emplacement or modification of a single lithology rather than systematic continuous low energy abrasion or wear over time comparison with particle morphology at other mars landing sites is consistent with the hypothesis that no secondary systematic transport or wide scale chemical alteration was active at a significant enough level to alter macromorphology in particular particle morphology at the mars pathfinder site shows stronger evidence of abrasion than along the spirit traverse suggesting mars pathfinder particles have undergone abrasion processes that particles in this study area have not additionally morphology indices have correlation coefficients near zero indicating that a fluvial transport mechanism is likely not responsible for morphology morphology and texture are instead related to origin and composition rather than subsequent modification morphology and texture support a volcanic origin possibly without modification but most likely altered primarily by ballistic impact implying that the spirit landing site and traverse may be utilized in the future as a standard site for characterization of impact derived morphology

the problem of heat flow density determination from inaccurate data abstract we present an inverse method for processing rough data from oil wells in order to evaluate the heat flow density assuming that the evaluations of temperatures and thermal resistivities present gaussian uncertainties we give formulas for computing the optimal value of the heat flow density and its standard deviation a synthetic example using likely assumptions on various uncertainties leads to the prediction that a standard deviation of about 10 mw m 2 could apply to heat flow estimates from oil well data for typical situations

the opposition surge and photopolarimetry of fresh and coated basalts abstract we present polarization phase curve measurements and analysis for three basalt samples fresh dark red varnished and dark gray varnished each sample displays a prominent opposition surge countering the widely held notion that only particulate surfaces and not bare rock will display this phenomenon the most likely cause of the opposition surge is coherent backscattering but the width of the surge suggests that other mechanisms may also contribute the photopolarimetric properties of the samples especially the negative branch parameters are most comparable to those of c class asteroids

mars exploration rover engineering cameras 1 nasa s mars exploration rover mer mission will place a total of 20 cameras 10 per rover onto the surface of mars in early 2004 fourteen of the 20 cameras are designated as engineering cameras and will support the operation of the vehicles on the martian surface images returned from the engineering cameras will also be of significant importance to the scientific community for investigative studies of rock and soil morphology the navigation cameras navcams two per rover are a mast mounted stereo pair each with a 45 square field of view fov and an angular resolution of 0 82 milliradians per pixel mrad pixel the hazard avoidance cameras hazcams four per rover are a body mounted front and rear facing set of stereo pairs each with a 124 square fov and an angular resolution of 2 1 mrad pixel the descent camera one per rover mounted to the lander has a 45 square fov and will return images with spatial resolutions of 4 m pixel all of the engineering cameras utilize broadband visible filters and 1024 1024 pixel detectors

heat flow in the utah wyoming thrust belt from analysis of bottom hole temperature data measured in oil and gas wells bottom hole temperature bht data from oil and gas wells represent a large albeit low quality data base for heat flow determinations a method for analyzing bht data sets that directly addresses the problem of noise in the data is presented and illustrated by application to 303 bhts from the anschutz ranch ar cave creek cc and anschutz ranch east are oil gas fields in the utah wyoming thrust belt located in the middle rocky mountain physiographic province of the western united states correction of raw bht data by means of a horner plot yields 81 corrected bhts an additional 90 bhts not suitable for a horner correction are corrected by means of a new bht correction which may be applied to any single bht for which a depth and time of measurement are known the average geothermal gradient at both ar cc and are is found to be 23 c km although an average gradient analysis fails to explain scatter in the data analysis of corrected bhts through inversion of a layered earth model yields estimates of formation thermal gradients and temperature fields at ar cc and are that are stable and unique with an average precision of 2 to 3 c thermal conductivity measurements were made on 360 drill cutting samples representing 14 thrust belt formations in situ conductivity is estimated using porosity from calibrated well logs heat flow is estimated by comparing temperature calculated by a two dimensional finite element model with temperature estimated from analysis of bht data analysis of bht data from the ar cc area yields an estimated regional heat flow of 60 mw m2 8 mw m2 a similar analysis at are results in an estimate of 58 mw m2 8 mw m2 these estimates are close to values determined for the wyoming basin and the central colorado plateau and imply that a thermal transition from the middle rocky mountains to elevated heat flow characteristic of the basin and range province 80 to 90 mw m2 must take place within 50 km

geology and mer target site characteristics along the southern rim of isidis planitia mars 1 the southern rim of the isidis basin contains one of the highest densities of valley networks several restricted paleolake basins and the stratigraphically lowest oldest terrain on mars geologic mapping in viking mgs moc and mola data odyssey themis data and other multispectral data products supports the presence of extensive fans of debris and sediments deposited along the inner rim of the isidis basin where large valleys enter the lowlands additional processes subsequent to the period of intense fluvial activity including mass flow analogous to some glacial processes have contributed to the materials accumulated on the margins of the isidis basin these have occurred along preexisting channels and valleys at the termini of major channels where they enter the plains along the highland lowland boundary if the abundant valley networks in highland terrains are the result of runoff accompanied by saturated groundwater flow as has been suggested in previous studies of ancient fluvial highland terrains then the extreme age and abundance of early valley networks in the libya montes highland rocks should have resulted in deposition of materials that record evidence for the long term presence of water in the form of aqueous alteration of polycrystalline constituents the material deposited along the basin margin is likely to consist of ancient altered highland rocks in several physical states weathered rounded and angular exposing both weathered and altered surfaces and exposures of alteration profiles in fractured faces and unweathered material from rock interiors debris fans shed off the southern rim of isidis planitia should contain materials that have experienced possible saturated groundwater flow residence within paleolake basins and derivative materials deposited during the most fluvially intensive part of martian geologic history many of these materials have also been reworked by ice related processes in situ measurements of the ancient crustal materials in the form of rocks within the debris fans and the weathered condition of the rocky material are potential sources for mineralogical evidence of climatic conditions in earliest martian geologic history the absence of alteration within rocks would on the other hand support the hypothesis that fluvial runoff during the earliest history of mars was geologically brief rather than long term and that long term saturated groundwater flow was not present determination of the presence or absence of alteration would have corresponding implications for hypotheses requiring the long term presence of aqueous solutions i e complex organic compounds and life a proposed mer site along the margin addresses realistic field science objectives of the mars exploration rover mission and the current goals of the mars exploration program in situ measurements may be important in deriving estimates of the longevity and intensity of past wetter climates

mineralogy of the paso robles soils on mars visible near infrared thermal and mossbauer spectroscopic data from the exposed bright track soil at the paso robles site within gusev crater mars indicate the presence of fe3 sulfates and possibly fe3 phosphates admixed with the host soil when the spectroscopic analyses are combined with constraints imposed by chemical data the determined dominant fe3 sulfate component is hydrous and all of the spectroscopic methods suggest that it is probably ferricopiapite or some closely related structurally similar species possibly mixed with other fe3 sulfates such as butlerite or parabutlerite or perhaps para coquimbite fibroferrite or metahohmanite such an assemblage is consistent with formation in a highly oxidized relatively dehydrated environment with the bulk sulfate assemblage having oh oh 2so4 of 0 4 some fe3 is likely to be associated with phosphates in the soil in the form of ferristrunzite or strengite

chemical multispectral and textural constraints on the composition and origin of rocks at the mars pathfinder landing site rocks at the mars pathfinder site are probably locally derived textures on rock surfaces may indicate volcanic sedimentary or impact generated rocks but aeolian abration and dust coatings prevent unambiguous interpretation multispectral imaging has resolved four spectral classes of rocks gray and red which occur on different surfaces of the same rocks pink which is probably soil crusts and maroon which occurs as large boulders mostly in the far field rocks are assigned to two spectral trends based on the position of peak reflectance the primary spectral trend contains gray red and pink rocks maroon rocks constitute the secondary spectral trend the spatial pattern of spectral variations observed is oriented along the prevailing wind direction the primary spectral trend arises from thin ferric coatings of aeolian dust on darker rocks the secondary spectral trend is apparently due to coating by a different mineral probably maghemite or ferrihydrite a chronology based on rock spectra suggests that rounded maroon boulders constitute the oldest petrologic unit a flood deposit succeeded by smaller cobbles possibly deposited by impact and followed by aeolian erosion and deposition nearly linear chemical trends in alpha proton x ray spectrometer rock compositions are interpreted as mixing lines between rock and adhering dust a conclusion supported by a correlation between sulfur abundance and red blue spectral ratio extrapolations of regression lines to zero sulfur give the composition of a presumed igneous rock the chemistry and normative mineralogy of the sulfur free rock resemble common terrestrial volcanic rocks and its classification corresponds to andesite igneous rocks of this composition may occur with clastic sedimentary rocks or impact melts and breccias however the spectral mottling expected on conglomerates or breccias is not observed in any apxs analyzed rocks interpretation of the rocks as andesites is complicated by absence of a 1 m pyroxene absorption band plausible explanations include impact glass band masking by magnetite or presence of calcium and iron rich pyroxenes and olivine which push the absorption band minimum past the imager s spectral range the inferred andesitic composition is most similar to terrestrial anorogenic icelandites formed by fractionation of tholeiitic basaltic magmas early melting of a relatively primitive martian mantle could produce an appropriate parent magma supporting the ancient age of pathfinder rocks inferred from their incorporation in hesperian flood deposits although rocks of andesitic composition at the pathfinder site may represent samples of ancient martian crust inferences drawn about a necessary role for water or plate tectonics in their petrogenesis are probably unwarranted

high resolution heat flow density in the lower congo basin 1 heat flow density hfd has been derived in the lower congo basin from 293 conventional probe measurements 424 oil exploration data and about 1 000 000 bottom simulating reflector bsr values each set of data provides independent estimates of temperature gradients associated with specific uncertainties and geographic distributions but a statistical comparison in overlapping domains shows a relatively good consistency in situ conductivity has been measured in conventional surveys and estimated from rock composition and porosity in oil exploration boreholes in the deep offshore measurements and estimates are consistently low and increase significantly toward the shelf domain thermal conductivity does not change significantly in the interval between the water bottom and the bsr and can be estimated from the surface measurements to provide an inference of hfd the combined sets of hfd in the lower congo basin cover the overall domain of the continental margin and a part of the oceanic domain high resolution imaging of the bsr by three dimensional 3 d seismic studies provides in addition good quality nominal resolution of 500 m in the deep offshore at short length scales on the order of kilometers large variations of hfd from 30 to 140 mwm 2 exist above salt diapirs and canyons related to heat refraction on the other hand no small scale effect related to fluid flow has been detected although active venting is known at larger length scale hfd in the deep offshore is different on both sides of the congo submarine channel 54 8 mwm 2 to the north and 48 12 mwm 2 to the south which are also characterized by different basin tectonic styles at the margin scale hfd is significantly different in the oceanic domain 42 3 mwm 2 the deep continental offshore 52 10 mwm 2 and the continental shelf 65 15 mwm 2 a progressive reduction of the radiogenic heat contribution in the extended continental crust is the more likely the cause of these differences mantle heat flow below the continental margin is consequently high compared to that expected 15 mwm 2 for old shields such as congo

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

mars exploration rover athena panoramic camera pancam investigation 1 the panoramic camera pancam investigation is part of the athena science payload launched to mars in 2003 on nasa s twin mars exploration rover mer missions the scientific goals of the pancam investigation are to assess the high resolution morphology topography and geologic context of each mer landing site to obtain color images to constrain the mineralogic photometric and physical properties of surface materials and to determine dust and aerosol opacity and physical properties from direct imaging of the sun and sky pancam also provides mission support measurements for the rovers including sun finding for rover navigation hazard identification and digital terrain modeling to help guide long term rover traverse decisions high resolution imaging to help guide the selection of in situ sampling targets and acquisition of education and public outreach products the pancam optical mechanical and electronics design were optimized to achieve these science and mission support goals pancam is a multispectral stereoscopic panoramic imaging system consisting of two digital cameras mounted on a mast 1 5 m above the martian surface the mast allows pancam to image the full 360 in azimuth and 90 in elevation each pancam camera utilizes a 1024 1024 active imaging area frame transfer ccd detector array the pancam optics have an effective focal length of 43 mm and a focal ratio of f 20 yielding an instantaneous field of view of 0 27 mrad pixel and a field of view of 16 16 each rover s two pancam eyes are separated by 30 cm and have a 1 toe in to provide adequate stereo parallax each eye also includes a small eight position filter wheel to allow surface mineralogic studies multispectral sky imaging and direct sun imaging in the 400 1100 nm wavelength region pancam was designed and calibrated to operate within specifications on mars at temperatures from 55 to 5 c an onboard calibration target and fiducial marks provide the capability to validate the radiometric and geometric calibration on mars

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

surface heat flow and the mantle contribution on the margins of australia 1 we present thermal data from 473 oil exploration wells in australia and new zealand approximately 2300 bottom hole temperatures are corrected to form a homogeneous set along with 86 temperatures from reservoir tests thermal conductivity profiles are estimated from a set of geophysical well logs using a recently developed neural network approach retaining wells in which temperature and thermal conductivity data overlap over an interval greater than 1000 m we estimate 10 heat flow values in the taranaki basin of new zealand and 270 values in the northwestern western and southern margins and in the intracontinental canning basin of australia the values are in the range 30 80 mw m 2 as a result of several differences in the data and methods our heat flow values are 10 20 mw m 2 lower compared to previously published estimates for the same wells in new zealand for australia our values are consistent with previously measured values and trends in the continental and marine regions on the northwestern and southeastern margins we interpret the variations as reflecting changes in the nature of the underlying basement consistent with onshore data it is inferred that the archean crust is depleted in radiogenic elements compared to proterozoic regions and that recent volcanism affects the eastern paleozoic area after removing from surface heat flow the sediment contributions including a permanent radiogenic heat component and a transient sedimentation effect a simple crustal model suggests that mantle heat flow on the continental margin bordering the pilbara craton is higher than below the craton itself moreover heat flow corrected for the sediment contributions is markedly lower in the petrel intracontinental basin than in the adjacent margin although the crust is thinner below this latter region as both are underlaid by the same basement this observation may indicate that the mantle contribution is also higher below that margin such a higher mantle heat flow on old continental margins is consistent with experiments of fluid convection below an insulating lid and suggests that the thermal regime of the continental lithosphere never returns to its prerift state as usually assumed by several thermomechanical models of evolution of continental margins

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

spectrophotometric properties of materials observed by pancam on the mars exploration rovers 2 opportunity 1 the panoramic camera pancam on the mars exploration rover opportunity acquired visible near infrared multispectral observations of soils and rocks under varying viewing and illumination geometries that were modeled using radiative transfer theory to improve interpretations of the microphysical and surface scattering nature of materials in meridiani planum nearly 25 000 individual measurements were collected of rock and soil units identified by their color and morphologic properties over a wide range of phase angles 0 150 at eagle crater in the surrounding plains in endurance crater and in the plains between endurance and erebus craters through sol 492 corrections for diffuse skylight incorporated sky models based on observations of atmospheric opacity throughout the mission disparity maps created from pancam stereo images allowed inclusion of local facet orientation estimates outcrop rocks overall exhibited the highest single scattering albedos 0 9 at 753 nm and most spherule rich soils exhibited the lowest 0 6 at 753 nm macroscopic roughness among outcrop rocks varied but was typically larger than spherule rich soils data sets with sufficient phase angle coverage resulting in well constrained hapke parameters suggested that models using single term and two term henyey greenstein phase functions exhibit a dominantly broad backscattering trend for most undisturbed spherule rich soils rover tracks and other compressed soils exhibited forward scattering while outcrop rocks were intermediate in their scattering behaviors some phase functions exhibited wavelength dependent trends that may result from variations in thin deposits of airfall dust that occurred during the mission

on the effect of continents on mantle convection at the earth s surface continents and oceans impose different thermal boundary conditions at the top of the mantle laboratory experiments are used to investigate the consequences of this for mantle convection the upper boundary of the experimental tank was made of copper plates enforcing a fixed temperature and had a conductive lid of finite width in the middle beneath this lid the thermal boundary condition was of the mixed type with a biot number depending on the dimensions and thermal conductivity of the lid experimental values of the biot number were scaled to earth values experiments were run for a large range of rayleigh numbers from 104 to 107 and for several lid widths the effects of temperature dependent viscosity and of the shape of the lid were investigated at steady state in all cases there is an upwelling beneath the conductive lid which feeds two symmetrical and elongated convective cells three different dynamic regimes were identified as a function of rayleigh number independently of the lid width at rayleigh numbers lower than 1 2 105 the upwelling is steady both in geometry and temperature structure at rayleigh numbers between 1 2 105 and 2 106 this central upwelling is intermittent at larger values of the rayleigh number there is no longer a simple upwelling structure but a set of small plumes rising together and distorted by a cellular circulation of large horizontal extent thus the conductive lid always imposes a large scale flow pattern the length of these convective cells is a function of lid width it is equal to the lid width at large values and decreases to the rayleigh benard value as the lid width decreases to zero a fluid loop model explains the most important features of this form of convection the cell length is such that the upwelling temperature is minimized for a given rayleigh number and lid width and is an increasing function of lid width and a decreasing function of rayleigh number transient experiments demonstrate that the large scale flow structure develops rapidly with even small horizontal temperature differences implications for the earth are that large scale convection cells exist in conditions which in the absence of continents would probably lead to a chaotic convection pattern dominated by plumes at high rayleigh number continental breakup is effected by a large scale line upwelling structure which includes a number of individual plumes

structural styles in the perth basin associated with the mesozoic break up of greater india and australia abstract the perth basin constitutes one of the principal tectonic features along the western continental margin of australia and formed through permo cretaceous rifting of greater india and australia it is composed of northerly striking sub basins troughs and ridges bounded by faults which display evidence for normal dip slip and possibly dextral strike slip movement transfer faults divide the basin into compartmentalised regions of similar structural style extension and transtension occurred during the jurassic early cretaceous associated with continental break up stretching was accommodated mainly by the reactivation of pre existing northerly oriented faults which display both planar and listric geometries the darling fault system along the eastern margin of the basin has a planar profile the hanging wall succession in the adjoining perth basin has undergone block rotation and tilting with syn sedimentary depositional thickening of rock units towards the fault listric normal faults occur in both the onshore and offshore portions of the basin and influence geometry of the sub basins dip on these faults decreases through the basin sequence and probably soles out in the upper level of basement rollover anticlines develop within the hangingwall of these structures extension oblique to the main structural trends of the basin in the late jurassic the earliest cretaceous resulted in dextral strike slip movement along major north striking faults and the development of en echelon folds in the basin compressive deformation developed during this event at constraining bends of the major fault systems two orientations of transfer zones are recognised and significantly influence basin structures the first are east west trending transfer faults which formed in the permian and were reactivated during jurassic extension but can only be recognised in the northernmost perth basin these transfer faults link basin segments of different characteristics and transfer dip displacement among the northerly striking faults the transfer zones striking nw only influence late jurassic early cretaceous age deformation features they are characterised by either a swing in a left lateral sense in the orientation of northerly striking fractures as they cross the transfer zones or a termination of the fracture at the transfer zone the transfer zones are parallel to and may be related to transform belts in the indian oceanic crust basin wide uplift occurred during the break up and resulted in basin inversion and erosion of up to thousands of metres of the sedimentary succession folding by dextral strike slip motion along the darling urella fault system also inverted the pre break up sequences in major onshore depocentres

heat flow and thermal evolution of a passive continental margin from shelf to slope a case study on the pearl river mouth basin northern south china sea abstract the pearl river mouth basin prmb the largest basin in the northern continental margin of the south china sea scs has been one of the key areas to characterize geothermal field and thermal evolution of a passive continental margin the thermal history of the pearl river mouth basin is related to the seafloor spreading of the scs in the late early oligocene heat flow measurements show that the prmb is characterized by a high background heat flow with average heat flow of 71 8 13 6 mw m2 the present day heat flow of the northern scs increases from the northern shelf with the thick crust to the southern slope with the thinned crust this study employs forward and inverse modeling to simulate the rift and post rift processes exampled by four wells at different structural settings two thermal evolution models of the prmb are established for continental shelf and continental slope in the continental shelf heat flow increased rapidly twice during the syn rift stage and then followed by continuous thermal subsidence with heat flow value decreased during the post rift stage while the heat flow in the slope continuously increased due to lithospheric thinning mantle upwelling and resulting multi episode seafloor spreading in scs during the neogene post rift stage which is different from the previously proposed decreasing heat model for the slope during the post rift heat flow gradually reduced after the cessation of the sea floor spreading 10 ma the local multi staged magmatic activities mainly contribute to the high level of maturity in the liwan sag located in the lower slope

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

surface geology from viking landers on mars a second look aside from reddish dust products of martian weathering are not abundantly obvious on viking lander images surface stones appear sound spalls and disintegration fragments are largely lacking pitting of stones is probably not due to differential weathering and reddish stone colors more likely result from adhered dust than from patination judging from wind scoured drifts deflated ground rippled bed forms lee side tails basal scours fretted rocks and ubiquitous dust wind is currently the most effective transportive and erosive agent the dogma that martian eolian material is almost exclusively of 10 100 size is challenged by granule ripples and the possibility that wind drifted deposits consist largely of sand sized particles fretting is more common than faceting on martian ventifacts crusts on martian surface fines are more akin to case hardened rinds than to true duricrust crusting a possibly continuing process may be the product of atmospheric breathing of the regolith pits on surfaces of many martian stones are probably vesicles modified by eolian erosion pits on nonvesicular rocks may be solely the product of wind blasting vesicular lava dense lava and breccias are the most likely rocks among surface stones around the landers the bedrock outcrops near vl 1 may be large boulders embedded in a breccia substrate pyroclastics seem a likely constituent of surface deposits

defining the updip extent of the gas hydrate stability zone on continental margins with low geothermal gradients 1 the distribution of gas hydrate on a continental slope is often characterized as a wedge that pinches out on the seafloor this part of the hydrate stability zone is particularly relevant for studies of the dynamics of hydrate accumulations such as processes related to slope stability or hydrate dissociation leading to methane release into the overlying ocean for regions with very low geothermal gradients we have produced a series of thermobaric models of the shallow hydrate stability zone that contain an unexpected geometrical distribution of hydrated sediments in these models the shallowest part of the stability field thickens and bulges landward such a feature is more likely to happen in regions where low geothermal gradients are further lowered by high sedimentation rates also the effect is greater beneath colder oceans although a hydrate stability zone bulge would be difficult to image with conventional seismic methods there are numerous locations around the world where such a system could develop

athena mimos ii mossbauer spectrometer investigation 1 mossbauer spectroscopy is a powerful tool for quantitative mineralogical analysis of fe bearing materials the miniature mossbauer spectrometer mimos ii is a component of the athena science payload launched to mars in 2003 on both mars exploration rover missions the instrument has two major components 1 a rover based electronics board that contains power supplies a dedicated central processing unit memory and associated support electronics and 2 a sensor head that is mounted at the end of the instrument deployment device idd for placement of the instrument in physical contact with soil and rock the velocity transducer operates at a nominal frequency of 25 hz and is equipped with two 57co rh mossbauer sources the reference source 5 mci landed intensity reference target fe2o3 plus fe0 and pin diode detector are configured in transmission geometry and are internal to the instrument and used for its calibration the analysis mossbauer source 150 mci landed intensity irradiates martian surface materials with a beam diameter of 1 4 cm the backscatter radiation is measured by four pin diode detectors physical contact with surface materials is sensed with a switch activated contact plate the contact plate and reference target are instrumented with temperature sensors assuming 18 fe for martian surface materials experiment time is 6 12 hours during the night for quality spectra i e good counting statistics 1 2 hours is sufficient to identify and quantify the most abundant fe bearing phases data stored internal to the instrument for selectable return to earth include mossbauer and pulse height analysis spectra 512 and 256 channels respectively for each of the five detectors in up to 13 temperature intervals 65 mossbauer spectra engineering data for the velocity transducer and temperature measurements the total data volume is 150 kb the mass and power consumption are 500 g 400 g for the sensor head and 2 w respectively the scientific measurement objectives of the mossbauer investigation are to obtain for rock soil and dust 1 the mineralogical identification of iron bearing phases e g oxides silicates sulfides sulfates and carbonates 2 the quantitative measurement of the distribution of iron among these iron bearing phases e g the relative proportions of iron in olivine pyroxenes ilmenite and magnetite in a basalt 3 the quantitative measurement of the distribution of iron among its oxidation states e g fe2 fe3 and fe6 and 4 the characterization of the size distribution of magnetic particles special geologic targets of the mossbauer investigation are dust collected by the athena magnets and interior rock and soil surfaces exposed by the athena rock abrasion tool and by trenching with rover wheels