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

the longwave infrared 3 14μm spectral properties of rock encrusting lichens based on laboratory spectra and airborne sebass imagery there has been a progressive emergence of airborne longwave spectral sensing capabilities e g spatially enhanced broadband array spectrograph system sebass of potential value for remote geological mapping in arctic and subarctic regions however the presence of rock encrusting lichens can obscure spectral features diagnostic of minerals this paper documents the longwave 3 14 m spectral transmittance and reflectance properties of rock encrusting lichens as determined from lichen samples from rock samples encrusted with lichens and observations from airborne sebass imagery the samples and sebass airborne hyperspectral imagery were acquired over the 1 9 ga cape smith greenstone belt of northern quebec within the restrahlen region 8 12 m where silicate minerals display peaks in reflectance the maximum reflectance observed for rock encrusting lichens is 1 6 these lichens display low reflectance and spectral contrast and approach a blackbody behavior for lichens detached from the rock substrate spectra obtained on two backgrounds of contrasting reflectance are similar 0 75 difference in reflectance indicating that lichens transmit little or no light detailed observations reveal three features that can be attributed to organic compounds in lichens 3 41 6 58 8 13 m the feature located near 8 13 m is a reflectance peak within the restrahlen region of enhanced mineral reflectance a measure of the strength of this feature and the mean reflectance in the restrahlen region for laboratory data and sebass imagery reveals linear mixing trajectories between a lichen endmember and a suite of geological endmembers this data representation enables the visualization of mixing lines the delineation of geologically informative endmembers and provides a means to mask pixels in imagery that encompass the greatest abundance of rock encrusting lichens therefore facilitating geological mapping the implications for the detection of geological endmembers and mapping are discussed

age constraints on tarkwaian palaeoplacer and lode gold formation in the tarkwa damang district sw ghana two major epigenetic gold forming events are recorded in the world class gold province of southwest ghana a pre tarkwaian event was the source of the world class tarkwa palaeoplacers whereas post birimian and tarkwaian deformation which was related to the eburnean orogeny gave rise to the world class e g prestea to giant e g obuasi orogenic gold deposits which have made the region famous for more than 2 500 years a maximum age of 2133 4 ma for tarkwaian sedimentation is provided by 71 of 111 concordant shrimp ii u pb dates from detrital zircons in tarkwaian clastic rocks from damang and bippo bin northeast of tarkwa the overall data distribution broadly overlaps the relatively poorly constrained ages of birimian volcanism and associated dixcove type granitoid emplacement indicating syntectonic development of the tarkwaian sedimentary basin these zircon ages argue against derivation of the palaeoplacer gold from an orogenic gold source related to the compressional phase of an orogeny significantly older than the eburnean orogeny instead they suggest that the gold source was either orogenic gold lodes related to an earlier compressional phase of a diachronous eburnean orogeny or ca 2200 2100 ma intrusion related gold lode the co2 rich fluid inclusions in associated vein quartz pebbles are permissive of either source at the damang deposit an epigenetic orogenic lode gold system clearly overprinted and sulphidised low grade palaeoplacer hematite magnetite gold occurrences in the banket series conglomerate within the tarkwaian sedimentary sequence gold mineralisation is demonstrably post peak metamorphism as gold related alteration assemblages overprint metamorphic assemblages in host rocks in alteration zones surrounding the dominant subhorizontal auriferous quartz veins there are rare occurrences of hydrothermal xenotime which give a shrimp u pb age of 2063 9 ma for gold mineralisation the similar structural timing of epigenetic gold mineralisation in tarkwaian host rocks at damang to that in mainly birimian host rocks elsewhere in southwest ghana particularly at obuasi suggests that 2063 9 ma is the best available age estimate for widespread orogenic gold mineralisation in the region argon argon ages of 2029 4 and 2034 4 ma for hydrothermal biotite from auriferous quartz veins appear to represent uplift and cooling of the region below about 300 c as estimates of the temperature of gold mineralisation are higher at around 400 c if peak metamorphism with temperatures of about 550 c is assumed to have occurred at about 2100 ma the biotite ages in combination with the xenotime age suggest a broadly constant uplift rate for the region of about 1 km per 10 million years from about 2100 to 2025 ma

development of a novel image analysis procedure to quantify biological porosity and illuvial clay in large soil thin sections among other driving forces climate change may lead to significant modifications of soil properties through variations of the intensity and dynamics of a number of soil processes including the especially sensitive and ubiquitous processes of bioturbation and illuviation progress toward the quantification of these processes needs to be made as a first step in order to ascertain or predict the impact of climate change in this study we develop and validate through an exhaustive accuracy assessment a digital 2d image analysis method adapted to large soil thin sections leading to the quantification characterization and classification of pores and illuvial clay features considered diagnostic of bioturbation and illuviation respectively the need to consider large soil thin sections 14 x 6 cm stems from observations that areas from 684 mm2 to more than 5 000 mm2 are needed to obtain representative measurements of fragments of illuvial clay papules and porosity associated with earthworms respectively whereas the soil heterogeneity in thin sections of such a large size prohibits the use of classical global and colorimetric image analysis procedures we succeeded to quantify and characterize the porosity and illuvial clay features with accuracies as high as 96 for porosity and 92 for illuvial clay by carefully considering different levels of soil organization from aggregates to individual illuvial clay features quantification of the size and the shape of pores and of illuvial clay features makes it possible to develop morphological classifications distinguishing pores of biological origin earthworms or roots from others or clay coatings and infillings from papules all these data are particularly useful to better characterize underlying soil processes results suggest that the proposed methodology provides an accurate and representative quantification of biological porosity and illuvial clay features in large thin sections we argue that the use of this approach could be extended to study and quantify bioturbation and illuviation intensities at the profile scale

optical constants for asian dust in midinfrared region asian dust aerosols are composed of quartz plagioclase k feldspar calcite and phyllosilicates the optical constants for mixtures of these minerals are important not only to understand the effects of asian dust on climate but also to retrieve the properties of asian dust in this work the optical constants for labradorite and orthoclase representative minerals of plagioclase and k feldspar respectively are determined for the spectral range of 500 2000 cm 1 using bidirectional reflectance data from the advanced spaceborne thermal emission and reflection radiometer assuming an internal mixture of component minerals the effective refractive indices for asian dust are calculated using bruggeman s rule the results are proposed as optical constants for asian dust and differ from those for other dust aerosols such as the refractive indices for saharan dust derived from aerosol samples collected at barbados the imaginary refractive index for asian dust is larger indicating more absorptive than the index for saharan dust in the range of 1000 1300 cm 1 using the optical constants derived in this study the brightness temperatures of satellite measurements are simulated for typical loading scenarios of asian dust aerosols the simulated brightness temperatures exhibit a notable decrease with wave number in the region of 800 1000 cm 1 the results also corroborate the spectral features of the atmospheric infrared sounder airs measurements for an asian dust storm airs brightness temperatures near 1223 cm 1 lower than the maximum near 830 cm 1 can also be simulated using the derived optical constants for asian dust

space weathering effects in diviner lunar radiometer multispectral infrared measurements of the lunar christiansen feature characteristics and mitigation multispectral infrared measurements by the diviner lunar radiometer experiment on the lunar renaissance orbiter enable the characterization of the position of the christiansen feature a thermal infrared spectral feature that laboratory work has shown is proportional to the bulk silica content of lunar surface materials diviner measurements show that the position of this feature is also influenced by the changes in optical and physical properties of the lunar surface with exposure to space the process known as space weathering large rayed craters and lunar swirls show corresponding christiansen feature anomalies the space weathering effect is likely due to differences in thermal gradients in the optical surface imposed by the space weathering control of albedo however inspected at high resolution locations with extreme compositions and christiansen feature wavelength positions silica rich and olivine rich areas do not have extreme albedos and fall off the albedo christiansen feature wavelength position trend occupied by most of the moon these areas demonstrate that the christiansen feature wavelength position contains compositional information and is not solely dictated by albedo an optical maturity parameter derived from near ir measurements is used to partly correct diviner data for space weathering influences

estimating silicic lava vesicularity with thermal remote sensing a new technique for volcanic mapping and monitoring remote monitoring of active lava domes pro vides insights into the duration of continued lava extru sion and detection of potentially associated explosive activity on inactive flows variations in surface texture ranging from dense glass to highly vesicular pumice can be related to emplacement time volatile content and internal structure pumiceous surface textures also pro duce changes in thermal emission spectra that are clear ly distinguishable using remote sensing spectrally the textures describe a continuum consisting of two pure end members obsidian and vesicles the distinct spec tral features of obsidian are commonly muted in pu mice due to overprinting by the vesicles which mimic spectrally neutral blackbody emitters assuming that this energy combines linearly in direct proportion to the percentage of vesicles the surface vesicularity can be estimated by modeling the pumice spectrum as a lin ear combination of the glass and blackbody spectra based on this discovery a linear retrieval model using a least squares fitting approach was applied to airborne thermal infrared data of the little glass mountain and crater glass rhyolite flows at medicine lake volcano california as a case study the model produced a ve sicularity image of the flow with values from 0 to f70 which can be grouped into three broad textural classes dense obsidian finely vesicular pumice and coarsely vesicular pumice values extracted from the image compare well with those derived from sem anal ysis of collected samples as well as with previously re ported results this technique provides the means to accurately map the areal distributions of these textures resulting in significantly different values from those de rived using aerial photographs if applied to actively deforming domes this technique will provide volcano logists with an opportunity to monitor dome wide de gassing and eruptive potential in near real time in july 1999 such an effort will be possible for the first time when repetitive global multispectral thermal infrared data become available with the launch of the advanced spaceborne thermal emission and reflectance ra diometer aster instrument aboard the earth ob serving system satellite

ore detection and grade estimation in the sudbury mines using thermal infrared reflectance spectroscopy this pilot study investigated the usefulness of thermal infrared reflectance tir spectroscopy to estimate ore grade in an underground environment and to separate ore bearing samples from their host rocks work was carried out under laboratory conditions to test the initial concept all samples had naturally broken faces to mimic the situation in a freshly blasted underground opening a total of 26 samples including massive and disseminated ores were collected from eight mines around the sudbury basin in ontario rock surfaces were measured wet and dry to address environmental conditions encountered underground to separate barren rocks from ores and for ore grade estimation an important finding of this research is that in the region of 1319cm 1 most known silicate minerals converge to a common reflectance minima 1 5 but massive and disseminated sulfides have distinctly higher reflectance individual sulfide minerals chalcopyrite pyrrhotite pentlandite however do not reveal diagnostic fea

thermal infrared spectroscopy on feldspars successes limitations and their implications for remote sensing abstract minerals of the feldspar group are the most common on earth feldspars are economically important in two ways either as industrial minerals or as a vector to ore for mineral deposits in order to use feldspars for classifying rock compositions or metasomatic conditions during rock alteration events there is a need for analytical methods to identify and classify feldspars traditionally feldspar composition and structure have been investigated using methods such as optical microscopy electron microprobe analysis empa cathodoluminescence and x ray diffraction xrd analysis in this paper infrared techniques 0 7 25 m are reviewed in detail and investigated in how far some of the traditional analytical methods can be replaced by infrared spectroscopy successes as well as limitations of infrared approaches are highlighted and existing work is scrutinized in terms of its applicability to remote sensing techniques even though numerous studies on mid infrared mir spectroscopy of feldspars exist their results often cannot be directly related to remote sensing applications examples are the effects of feldspar twinning exsolution textures and structural state on infrared spectra the applicability of the results to emission remote sensing requires further research it has been shown that linear unmixing of laboratory infrared spectra of rocks works fairly well detection limits for feldspar are around 5 and plagioclase composition can be determined within error margins of 4 anorthite component infrared spectroscopy can however not detect compositional zonation or different generations of feldspars infrared spectra represent the current average plagioclase and average alkali feldspar composition in the sample with several new airborne instruments under development it is opportune to focus upcoming research efforts on developing standardized processing techniques and spectral feldspar indices for thermal infrared imagery commercially interesting products include numbers of feldspars species plagioclase and alkali feldspar composition their structural state and relative or semi quantitative abundance in the rocks

thermal infrared 2 5 13 5 μm spectroscopic remote sensing of igneous rock types on particulate planetary surfaces fundamental molecular vibration bands are significantly diminished by scattering thus such bands in spectra of fine particulate regoliths i e dominated by 5 m particles or regoliths displaying a similar scale of porosity are difficult to use for mineralogical or rock type identification consequently other spectral features have been sought that may be more useful in spectroscopic remote sensing of composition we find that mineralogical information is retained in overtones and combination tones of the fundamental molecular vibrations in the 3 0 to 7 0 m region but that relatively few minerals have a sufficiently distinctive band structure to be unambiguously identified with currently available techniques more significantly identification of general rock type as defined by the scfm chemical index scfm sio2 sio2 cao feo mgo is possible using spectral features associated with the principal christiansen frequency and with a region of relative transparency between the si o stretching and bending bands however environmental factors may affect the appearance and wavelengths of these features finally prominent absorption bands may result from the presence of relatively small amounts of water hydroxyl or carbonate because absorption bands exhibited by these materials in the 2 7 to 4 0 m region where silicate spectra are otherwise featureless increase strongly in spectral contrast with decreasing particle size such materials are thus detectable in very small amounts in a particulate regolith composed predominantly of silicate minerals

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

laboratory emissivity measurements of the plagioclase solid solution series under varying environmental conditions 1 new laboratory thermal infrared emissivity measurements of the plagioclase solid solution series over the 1700 400 cm 1 6 25 m spectral range are presented thermal infrared tir spectral changes for fine particulate samples 0 25 m are characterized for the first time under different laboratory environmental conditions ambient terrestrial like half vacuum mars like vacuum and vacuum with cooled chamber lunar like under all environmental conditions the christiansen feature cf is observed to vary in a systematic way with na rich end member albite having a cf position at the highest wave number shortest wavelength and the ca rich end member anorthite having a cf position with the lowest wave number longest wavelength as pressure decreases to 10 3 mbar four observations are made 1 the cf position shifts to higher wave numbers 2 the spectral contrast of the cf increases relative to the rb 3 the spectral contrast of the rb in the 1200 900 spectral range decreases while the spectral contrast of the rb in the 800 400 spectral range either increases or remains the same and 4 the tf disappears a relationship between the wavelength position of the cf measured under simulated lunar conditions and plagioclase composition an is developed although its exact form may evolve with additional data this linear relationship should be applied to current and future tir data sets of the moon our new spectral measurements demonstrate how sensitive thermal infrared emissivity spectra of plagioclase feldspars are to the environmental conditions under which they are measured and provide important constraints for interpreting current and future thermal infrared data sets

spectral characterization and aster based lithological mapping of an ophiolite complex a case study from neyriz ophiolite sw iran abstract the neyriz ophiolite occurs along the zagros suture zone in sw iran and is part of a 3000 km obduction belt thrusting over the edge of the arabian continent during the late cretaceous this complex typically consists of altered dunites and peridotites layered and massive gabbros sheeted dykes and pillow lavas and a thick sequence of radiolarites reflectance and emittance spectra of neyriz ophiolite rock samples were measured in the laboratory and their spectra were used as endmembers in a spectral feature fitting sff algorithm laboratory spectral reflectance measurements of field samples showed that in the visible through shortwave infrared vnir swir wavelength region the ultramafic and gabbroic rocks are characterized by ferrous iron and fe mg oh spectral features and the pillow lavas and radiolarites are characterized by spectral features of ferric iron and al oh the laboratory spectral emittance spectra also revealed a wide wavelength range of si o spectral features for the ophiolite rock units after continuum removal of the spectra the sff classification method was applied to the vnir swir 9 band stack and to the 11 band data set of swir and tir data sets of the advanced spaceborne thermal emission and reflection radiometer aster sensor using field spectra as training sets for evaluating the potential of these data sets in discriminating ophiolite rock units output results were compared with the geological map of the area and field observations and were assessed by the use of confusion matrices the assessment showed in terms of kappa coefficient that the sff classification method with continuum removal applied to the swir data achieved excellent results which were distinctively better than those obtained using vnir swir data and tir data alone

quantitative compositional analysis using thermal emission spectroscopy application to igneous and metamorphic rocks the mineral composition of a suite of igneous and metamorphic rocks was determined using the thermal infrared emission spectra of these rocks in a linear spectral deconvolution algorithm this algorithm assumes that the infrared spectrum of each rock is a linear mixture of the component mineral spectra weighted by volume abundance a diverse suite of 36 common rock forming and accessory minerals was used in the deconvolution the model was tested by comparing the mineralogy derived from the infrared spectrum with petrographically estimated abundances for 45 igneous and 51 metamorphic rock samples the mineral abundances derived from these two techniques agree to within 67 15 for the primary minerals feldspar pyroxene quartz and calcite dolomite and 69 17 for secondary minerals such as micas and amphiboles these differences are comparable to the error for traditional thin section mode estimates which are 65 15 for major minerals and 5 for minor minerals the detection limit for the primary and secondary minerals found in the rocks analyzed ranged from 5 to 10 each major rock type studied here was easily distinguished by its spectral characteristics the best results in both the qualitative determination of the rock type and dominant minerals and the quantitative reproduction of absorption features and mineral composition were obtained for igneous rock samples for metamorphic rocks pelite and quartzo feldspathic samples gave slightly better results than calcareous or mafic samples a controlled analysis in which the end member suite was reduced based on an initial estimate of the rock type only improved the results by several percent for most primary and secondary minerals the quality of the obtained results demonstrates that a linear deconvolution of infrared emission spectra provides an accurate rapid technique for determining the quantitative mineral composition of rock samples in a laboratory and has application to future in situ measurements

analysis of lunar pyroclastic deposit feo abundances by lro diviner 1 thermal infrared reflectance spectra of rock forming minerals include a prominent minimum near 8 m known as the christiansen feature cf the inflection point wavelength is sensitive to the degree of polymerization of silicates which is strongly influenced by major cations notably iron in the minerals laboratory spectra of lunar soils demonstrate that the cf location is closely correlated to the sample s bulk feo abundance across the full range of apollo soil samples including pyroclastic glass this correlation is the basis for estimating lunar surface feo abundances using orbital thermal infrared measurements the diviner lunar radiometer experiment on the lunar reconnaissance orbiter includes three thermal infrared channels selected to determine the cf positions for sites across the lunar surface diviner measurements are used to derive feo abundances in the aristarchus sulpicius gallus and rima fresnel pyroclastic deposits the calculated feo abundances for aristarchus and sulpicius gallus lie within the compositional range of feo rich pyroclastic glasses but outside the range of most mare soils supporting the interpretations of these deposits as glass rich the calculated feo abundance for the rima fresnel deposit is close to that of mare soils supporting a contention that this deposit is dominated by basaltic fragments rather than glass the diviner measurements hold the potential to determine feo abundances in many lunar pyroclastic deposits a better understanding of these compositions will provide insight into the magmatic history and composition of the lunar interior as well as an enhanced inventory of potential resources for future human exploration

plagioclase compositions derived from thermal emission spectra of compositionally complex mixtures implications for martian feldspar mineralogy 1 the compositions of plagioclase the most abundant mineral in the martian crust reflect changing conditions during magmatic evolution plagioclase contains spectral features at thermal infrared wavelengths that permit its detection by thermal emission spectrometers thermal emission spectrometer tes thermal emission imaging system themis and miniature tes mini tes on mars spacecraft previous studies have determined the accuracy with which average plagioclase compositions can be modeled in simple two component sand mixtures and terrestrial volcanic rocks studies of terrestrial rock analogs suffer from difficulties in accurately determining the average plagioclase composition for comparison with the spectrally modeled composition sand mixtures however provide a means of controlling plagioclase compositions for direct comparison to those modeled by linear deconvolution this has allowed us to address how compositional complexity may affect our ability to derive average plagioclase compositions from thermal emission data in this study we examine the accuracy with which average plagioclase compositions can be modeled from emission spectra of complex mixtures of three four and five compositions of coarse 500 850 m plagioclase sand additionally we examine multiphase mixtures of plagioclase with pyroxene olivine magnetite and ilmenite that are analogous to selected martian surface materials increasing the number of plagioclase compositions or introducing additional mineral phases does not affect the accuracy previously reported for modeling average plagioclase compositions plagioclase can be modeled to within 6 an of measured compositions at laboratory tes themis and mini tes resolution within 1 standard deviation

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

the m3 project 2 global distributions of mafic mineral abundances on mars abstract a radiative transfer model was used to reproduce several millions of omega observatoire pour la mineralogie l eau les glaces et l activite spectra representative of igneous terrains of mars this task provided the modal composition and grain sizes at a planetary scale the lithology can be summarized in five mineral maps at km scale we found that the low albedo equatorial regions of the martian surface from 60 s to 30 n are globally dominated by plagioclase with average abundance 50 vol and pyroxenes with total averaged abundance close to 40 vol an evolution of the lcp lcp hcp ratio is observed with time at the global scale suggesting an evolution of the degree of partial melting throughout the martian eras olivine and martian dust are minor components of the modelled terrains the olivine distribution is quite different from the other minerals because it is found on localized areas with abundance reaching 20 vol a statistical approach to classify the pixels of the abundances maps using k means clustering highlighted seven distinct mineral assemblages on the surface this classification illustrates that diverse mineralogical units are found in the noachian and hesperian terrains which suggests the presence of various and complex magmatic processes at a global scale during the two oldest eras the chemical composition was derived from the modal composition maps the omega derived chemical composition is quite consistent with several distinctive geochemical characteristics previously considered as fingerprints of the martian surface a major discrepancy is in regards to the fe content that is significantly smaller than soil and rock analyses from grs and in situ measurements the discrepancy could be partly explained by the assumptions used for the spectral modelling or could also indicate surface alteration rinds

mid infrared spectroscopy of impactites from the nordlinger ries impact crater abstract this study is part of an effort to build a mid infrared database 7 14 m of spectra for mertis mercury radiometer and thermal infrared spectrometer an instrument onboard of the esa jaxa bepicolombo space probe to be launched to mercury in 2017 mercury was exposed to abundant impacts throughout its history this study of terrestrial impactites can provide estimates of the effects of shock metamorphism on the mid infrared spectral properties of planetary materials in this study we focus on the nordlinger ries crater in southern germany a well preserved and easily accessible impact crater with abundant suevite impactites suevite and melt glass bulk samples from otting and aumuhle as well as red suevite from polsingen were characterized and their reflectance spectra in mid infrared range obtained in addition in situ mid infrared spectra were made from glasses and matrix areas in thin sections the results show similar but distinguishable spectra for both bulk suevite and melt glass samples as well as in situ measurements impact melt glass from aumuhle and otting have spectra dominated by a reststrahlen band at 9 3 9 6 m bulk melt rock from polsingen and bulk suevite and fine grained matrix have their strongest band between 9 4 and 9 6 m there are also features between 8 5 and 9 m and 12 5 12 8 m associated with crystalline phases there is evidence of weathering products in the fine grained matrix such as smectites mercury endured many impacts with impactors of all sizes over its history so spectral characteristics observed for impactites formed only in a single impact like in the ries impact event can be expected to be very common on planetary bodies exposed to many more impacts in their past we conclude that in mid infrared remote sensing data the surface of mercury can be expected to be dominated by features of amorphous materials

infrared reflectance spectra 2 2 15 μm of plagioclase feldspars laboratory results show that 1 the christiansen frequency cf feature in mid infrared reflectance spectra of powders can be used to accurately distinguish plagioclase composition and 2 the wavelength position of the cf is not affected by vitrification of the plagioclase although the cf position does not distinguish glass from crystalline forms of plagioclase other features combination tone overtone restrahlen bands in the mid ir spectra of plagioclase can be used for that purpose these results have important implications for application of thermal emission spectroscopy to mapping the surface composition of regolith covered planetary bodies like the moon mars and asteroids

identification of sand sources and transport pathways at the kelso dunes california using thermal infrared remote sensing the kelso dune field is located in the eastern mojave desert california at the terminus of a sand transport pathway which has its primary source at the mojave river wash 50 km to the west initial examination of 1984 airborne thermal infrared multispectral scanner tims data showed significant spectral variations that indicate potential mineralogic heterogeneities within the active dunes this result prompted the collection of a suite of 48 sand samples in 1990 and the acquiring of new tims data in 1995 this new data set was used to test a newly developed linear spectral retrieval algorithm in conjunction with a spectral library of end member minerals results of this analysis produced images of end member minerals that showed marked variations within the dunes in addition standard petrographic techniques revealed that the dunes contain mineralogic variations and were much less quartz rich 42 than previously reported 70 90 point count results agreed with the spectral data to within an average of 5 3 for tims derived and 3 1 for laboratory derived mineralogic abundances high concentrations of several of the end member minerals on the surrounding alluvial fans indicate a potential nearby source for these minerals most evident is the presence of potassium feldspar from the fan that emanates from the providence mountains east of the dunes this previously unidentified potential sand input is not visible with other remote sensing techniques and was confirmed with additional field sampling much of the quartz and some plagioclase feldspar however appear to have been transported from the mojave river wash source as previously reported this study also validates the potential of using thermal remote sensing from future satellite based instruments to globally monitor desert fringe areas susceptible to the changing conditions of sand encroachment

using fourier transform infrared spectroscopy to determine mineral phases in sediments abstract in paleoenvironmental studies the mineralogical composition of sediments is an important indicator in combination with other indicators they contribute to the understanding of changes in sediment sourcing as well as in weathering and depositional processes fourier transform infrared spectroscopy ftirs spectra contain information on mineralogical composition because each mineral has a unique absorption pattern in the mid ir range although easily obtained ftir spectra are often too complex to infer mineral concentrations directly in this study we use a calibration set of ca 200 sediment samples conventionally measured using x ray diffraction xrd in order to develop multivariate partial least squares pls regression models relating mineral contents to sediment spectra good correlations were obtained for the most common minerals e g quartz k feldspar illite plagioclase smectite calcite correlation coefficients ranged from 0 85 to 0 92 coefficients for the validation varied from 0 64 to 0 80 the number of latent variables pls regression components in the models ranged between 3 and 7 and the range of variation of the rmsecv gradient was from 15 28 to 5 7