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

radiometric normalization and image mosaic generation of aster thermal infrared data an application to extensive sand sheets and dune fields abstract data from the advanced spaceborne thermal emission and reflection radiometer aster have a significant advantage over previous datasets because of the combination of high spatial resolution 15 90 m and enhanced multispectral capabilities particularly in the thermal infrared tir atmospheric window 8 12 m of the earth where common silicate minerals are more easily identified however the 60 km swath width of aster can limit the effectiveness of accurately tracing large scale features such as eolian sediment transport pathways over long distances the primary goal of this paper is to describe a method for generating a seamless and radiometrically accurate aster tir mosaic of atmospherically corrected radiance and from that extract surface emissivity for arid lands specifically sand seas the gran desierto in northern sonora mexico was used as a test location for the radiometric normalization technique because of past remote sensing studies of the region its compositional diversity and its size a linear approach was taken to transform adjacent image swaths into a direct linear relationship between image acquisition dates pseudo invariant features pifs were selected using a threshold of correlation between radiance values and change pixels were excluded from the linear regression used to determine correction factors the degree of spectral correlation between overlapping pixels is directly related to the amount of surface change over time therefore the gain and offsets between scenes were based only on regions of high spectral correlation the result was a series of radiometrically normalized radiance at surface images that were combined with a minimum of image edge seams present these edges were subsequently blended to create the final mosaic the advantages of this approach for tir radiance as opposed to emissivity data include the ability to 1 analyze data acquired on different dates with potentially very different surface temperatures as one seamless compositional dataset 2 perform decorrelation stretches dcs on the entire dataset in order to identify and discriminate compositional units and 3 separate brightness temperature from surface emissivity for quantitative compositional analysis of the surface reducing seam line error in the emissivity mosaic the approach presented here is valid for any aster related study of large geographic regions where numerous images spanning different temporal and atmospheric conditions are encountered

detectability of minerals on desert alluvial fans using reflectance spectra we analyzed the visible and near infrared reflectance spectra of soil samples collected from desert alluvial and colluvial surfaces in the cuprite mining district nevada these surfaces are downslope from hydrothermally altered volcanic rocks that contain spectrally characteristic minerals such as alunite and kaolinite coarse fractions of the soils on the alluvial fans are mineralogically variable and express the upslope lithologies fine fractions are remarkably similar mineralogically and spectrally in all samples because of dilution of local mineral components by regionally derived windblown dust theoretical models for spectral mixing and for particle size effects were used to model the observed spectral variations diagnostic mineral absorption bands in the spectra of fan materials were enhanced by computationally removing the spectrum of the homogenous fine soil component detection limits for minerals were found to be controlled by the sensitivity of the instrument the spectral contrast between the mineral and the background and the relative brightnesses of the mineral and the background these results show that spectral mixing models are useful for analyzing data with high spectral resolution obtained by field and aircraft spectrometers

regional aeolian dynamics and sand mixing in the gran desierto evidence from landsat thematic mapper images spatial variations in sand composition were mapped on a regional scale in a terrestrial sand sea the gran desierto of sonora mexico mesoscale mapping on a satellite image base allowed quantitative interpretation of the dynamic development of sand sheets and dunes the results were used to interpret the quaternary geologic history of the tectonically active region at the mouth of the colorado river landsat thematic mapper multispectral images were used to predict the abundance of different mineralogies of sand grains in a mixed aeolian terrain a spectral mixing model separated the effects of vegetation and topographically induced shading and shadow from the effects produced by different mineral and rock types compositions determined remotely agreed well with samples from selected areas within the spectral limitations of the thematic mapper a simple discrimination capability for active versus inactive sand surfaces is demonstrated based upon differences in the percentage of low albedo accessory grains occurring on dormant aeolian surfaces a technique for discriminating between low albedo materials and macroscopic shade is implemented by combining thermal images with the results of the spectral mixing model the image analysis revealed important compositional variations over large areas that were not readily apparent in the field

mapping of spectral variations on the surface of mars from high spectral resolution telescopic images abstract we analyze a high spectral resolution r 200 visible and near infrared 0 44 1 02 m telescopic spectral image of mars to explore surface material variations across the observed face of the planet which is centered on sinus meridiani two independent analysis methods are employed linear mixture modeling and supervised spectral pattern classification with an artificial neural network four endmember type regions are identified with linear mixing further refinement is achieved with the nonlinear neural network classification algorithm separating eight units of geological significance differences in spectral features among the mapped units are characterized among the medium to high albedo units northern lowlands typified by chryse planitia show far less evidence of bulk crystalline hematite than western arabia or any other highland regions the relationship of these bright units to the globally distributed aeolian dust is not yet clear within our image low albedo regions with the most pronounced crystalline hematite signature primarily correlate with the classic dark regions with the exception of acidalia planitia spectral evidence for pyroxenes also correlates well with most of the classic low albedo regions but again acidalia planitia is the major exception significant spectral anomaly is also found in an equatorial region deucalionis regio a companion paper in this issue discusses the soil properties of deucalionis our data and analysis support a compositional trend that is consistent with the global geologic crustal dichotomy of mars namely that the younger northern lowlands contain less bulk crystalline hematite than southern highlands

changes in active eolian sand at northern coachella valley california abstract climate variability and rapid urbanization have influenced the sand environments in the northern coachella valley throughout the late 20th century this paper addresses changes in the spatial relationships among different sand deposits at northern coachella valley between two recent time periods by using satellite data acquired from the advanced spaceborne thermal emission and reflection radiometer aster the approach employed here involving multispectral thermal infrared tir data and spectral mixture analysis has shown that the major sand deposits can be spatially modeled at northern coachella valley the coarse grained quartz rich sand deposit is associated with active eolian sand and the mixed sandy soil and fine grained quartz rich sand deposits are associated with inactive eolian sand the fractional abundance images showed a significant decrease between 2000 and 2006 in the percentage of active sand in the major depositional area for fluvial sediment the whitewater river but also in two downwind areas the whitewater and willow hole reserves the pattern of the active sand appears to be related to variations in annual precipitation wet and dry years and river discharge in the northern coachella valley we suggest here that recent human modifications to the major watercourses that supply sand affect the capability of fluvial deposition areas to restore sediments over time and consequently the responses of the sand transport system to climate change becoming more sensitive to dry years where areas of active sand may shrink degrade and or stabilize faster the approach utilized in this study can be advantageous for future monitoring of sand in the northern coachella valley for management of these and similar environments

drainage of a deep magma reservoir near mayotte inferred from seismicity and deformation the dynamics of magma deep in the earth s crust are difficult to capture by geophysical monitoring since may 2018 a seismically quiet area offshore of mayotte in the western indian ocean has been affected by complex seismic activity including long duration very long period signals detected globally global navigation satellite system stations on mayotte have also recorded a large surface deflation offshore here we analyse regional and global seismic and deformation data to provide a one year long detailed picture of a deep rare magmatic process we identify about 7 000 volcano tectonic earthquakes and 407 very long period seismic signals early earthquakes migrated upward in response to a magmatic dyke propagating from moho depth to the surface whereas later events marked the progressive failure of the roof of a magma reservoir triggering its resonance an analysis of the very long period seismicity and deformation suggests that at least 1 3 km3 of magma drained from a reservoir of 10 to 15 km diameter at 25 to 35 km depth we demonstrate that such deep offshore magmatic activity can be captured without any on site monitoring recent seismicity near mayotte in the indian ocean is due to dyke propagation from and drainage of a 25 35 km deep magma reservoir according to an analysis of earthquake and deformation data

soil carbonate genesis in the pinacate volcanic field northwestern sonora mexico uranium series methods were used to date and evaluate pedogenic caco3 genesis in the pinacate volcanic field northwestern sonora mexico soils are developed in eolian deposits on lava flows 230th234u dates of pedogenic carbonate are mininum soil ages because of 1 the time needed to yield clasts from flows and to accrete enough carbonate to sample 2 subsequent additions of uranium and 3 continued solution and reprecipitation of carbonate rinds k ar dates of basalt flows are maximum soil ages maximum and minimum rates of caco3 accumulation are calculated from the th u dates and k ar dates respectively the mean maximum rate is 0 13 g caco3 cm2 1000 yr and the mean minimum rate is 0 05 g caco3 cm2 1000 yr least squares regressions of pedogenic carbonate and clay content and of th u ages against k ar ages suggest additions to soils from atmospheric sources throughout the late quaternary morphology of pedogenic carbonate and laboratory data for soluble salts indicate that the climate of the pinacate has not changed significantly during the past 150 000 yr soil variability is influenced by proximity of the eolian source near the periphery of the pinacate carbonate and clay are evenly distributed throughout soil profiles within the volcanic field carbonate and clay are concentrated in soil horizons suggesting that additions from atmospheric sources are slow enough to allow translocation

bacterially mediated authigenesis of clays in phosphate stromatolites authigenic clays in close textural relation to carbonate fluorapatite within finely laminated phosphate stromatolites of upper jurassic age have been studied using scanning electron microscopy sem transmission electron microscopy tem and analytical electron microscopy aem stromatolite laminae consist of hexagonal prisms of francolite sizes ranging between 0 1 and 1 m that are surrounded by poorly crystalline smectite and amorphous fe si al oxyhydroxides microanalyses show that smectite is fe rich with highly variable composition particularly regarding fe and si contents smectite has significant beidellitic montmorillonitic and non tronitic substitutions although the lack of fringe contrast in some areas adjacent to the smectite packets with 1 0 1 3 nm spacing is due to differences in orientation of layers textural and analytical data clearly indicate the presence of fe si al amorphous phases intimately intergrown with smectite the occurrence of poorly crystalline smectite and associated amorphous phases within microbially precipitated stromatolite laminae both as envelopes around and as pore fillings between extremely small calcium phosphate crystals demonstrates authigenic smectite growth from a precursor fe si al amorphous material this material is formed in close association with a phosphate rich precursor the textural and structural relations the preservation of chemical precursors of glauconite such as nontronitic montmorillonite and the presence of fe si al amorphous mineral phases imply crystallization of the observed crystalline phases from synsedimentary bacterially precipitated amorphous precursors during early diagenesis in postoxic environments carbonate fluorapatite was the first phase to crystallize from the primary gel smectite and associated amorphous fe si al oxyhydroxides were the residual material of the crystallization process the slow rate of transformation at low temperatures from fe si al rich gels to smectite explains the textural relations between the poorly crystalline phases and the phosphate crystals as well as the preservation of amorphous substances in relation to clays authigenic smectite represents the first step in glauconitization

remote sensing for exploration an overview background material on measurement techniques and their physical basis as applied to rocks soils and vegetation new developments in high spectral resolution remote sensing for mineralogic and vegetation mapping modified journal abstract

spectroscopic study of the moses lake dune field washington determination of compositional distributions and source lithologies 1 source lithologies and transport histories of materials within the ephrata fan are investigated data were collected using a variety of remote sensing laboratory spectroscopic and field observations and techniques laboratory thermal emission spectra were collected of bedrock within the grand coulee dune samples and clast deposits factor analysis target transformation and end member recovery techniques were applied to the set of dune samples as well as a set of grain size fractions the dune sample spectra are composed of three components that represent basalt granodiorite and clay compositions the basalt and granodiorite components are similar to spectra of clast and bedrock samples from the grand coulee and the ephrata fan the clay component is similar to weathering surfaces located within the dune field the same components were recovered from the set of grain size fractions from a single dune sample demonstrating a relatively higher basalt concentration with grain sizes greater than 250 m thermal infrared multispectral scanner tims data display significant intradune compositional variation and no discernable interdune compositional variation indicating that the basalt and granodiorite components were likely deposited simultaneously and subsequently separated by wind based on grain size basalt and granodiorite bedrock units within the channeled scablands are source materials for the deposits within the ephrata fan and moses lake dune field the columbia river located 20 km west of the dune field is not a likely source of material

quantitative analysis of planetary reflectance spectra with principal components analysis a technique is presented for quantitative analysis of planetary reflectance spectra as mixtures of particles on microscopic and macroscopic scales using principal components analysis this technique allows for determination of the endmembers being mixed their abundance and the scale of mixing as well as other physical parameters eighteen lunar telescopic reflectance spectra of the copernicus crater region from 600 nm to 1800 nm in wavelength are modeled in terms of five likely endmembers mare basalt mature mare soil anorthosite mature highland soil and clinopyroxene these endmembers were chosen from a similar analysis of 92 lunar soil and rock samples the models fit the data to within 2 rms it is found that the goodness of fit is marginally better for intimate mixing over macroscopic mixing

global map of eolian features on mars ten basic categories of eolian features on mars were identified from a survey of mariner 9 and viking orbiter images the ten features mapped are 1 light streaks including frost streaks 2 dark streaks 3 sand sheets or splotches 4 barchari dunes 5 transverse dunes 6 crescentic dunes 7 anomalous dunes 8 yardangs 9 wind grooves and 10 deflation pits the features were mapped in groups not as individual landforms and recorded according to their geographic positions and orientations on maps of 1 12 5 million or 1 25 million scale in the north polar region light and dark streaks indicate winds from the west and northwest frost streaks show northeast and northwest winds barchan dunes show southwest and west winds transverse dunes show east and west winds local erosional features show winds from the northwest or southeast and northeast or southwest in the middle and low northern latitudes streaks show northeast winds yardangs and deflation pits show mostly easterly and northeasterly winds in the low southern latitudes light streaks and dunes record northwest and northeast winds dark streaks record southeast winds in high southern latitudes most streaks and dunes record southeast and east winds in the south polar region light and frost streaks record southwest and northwest winds whereas dark streaks and transverse dunes show southeast winds the patterns recorded for ephemeral features conform to global conditions of strong southern spring and summer northern fall and winter wind circulation erosional features in bedrock indicate long term and perhaps ancient wind trends whereas depositional features may record relatively more recent winds wind directions indicated by yardangs pits and other erosional features seldom correspond to those shown by streaks these erosional features indicating winds of different directions than those that formed the streaks may have been carved when the effective regional winds on mars were different due to relative hemisphere insolation differences which are related to obliquity variations alternatively many yardangs and pits may be largely controlled by structure and carved along surface structural patterns or features that channeled both ancient and present day winds deflation pits in the mantled terrain may contain the best record of ancient wind trends these pits seem to have stratigraphically related orientations different stratigraphic units composing the mantle contain wind erosion pits that possibly record large scale wind direction changes because of long term changes in the obliquity of the mars

large scale low amplitude bedforms chevrons in the selima sand sheet egypt landsat images of the selima sand sheet in southwestern egypt display alternating light and dark chevron shaped patterns that occur downwind from low scarps and major dune fields images acquired between 1972 and 1988 indicate that these features move as discrete bedforms at a rate of up to 500 meters per year extremely long wavelength 130 to 1200 meters low amplitude 10 to 30 centimeters bedforms were measured in the field the light chevrons seen in the orbital data may be thin accumulations of active sand sheet deposits in the lee of these bedforms dark chevrons contain an admixture of coarse granule lag deposits that are continually winnowed by aeolian erosion on the windward sides of the large bedforms sediment transport budgets derived from orbital and field analyses suggest net movement of up to 83 000 cubic meters per year for a single light chevron such measurements can be used as a check on similar calculations from dunes and other smaller scale features to determine sand transport budgets for large areas of the eastern sahara

development of the gran desierto sand sea northwestern mexico three major eolian sand populations can be recognized in the gran desierto sand sea of northwestern mexico by using spectral data from the landsat thematic mapper in conjunction with textural and mineralogical studies of surface sands each sand population has distinct textural mineralogic and spectral properties that can be related to sand dune morphology and position with reference to source areas and transport paths of the sands the oldest eolian sediment in the sand sea was derived from the early to middle pleistocene colorado river that flowed through the area of the western gran desierto subsequent inputs of eolian sands came from the area of the present colorado river valley and the coast south of the sand sea the spatial and temporal pattern of eolian deposition in the region has been controlled by quaternary tectonic and climatic changes resulting in the episodic input and deposition of sand

spectral properties iron oxide content and provenance of namib dune sands this paper applies multispectral remote sensing techniques to map the fe oxide content over the entire namib sand sea spectrometric analysis is applied to field samples to identify the reflectance properties of the dune sands which enable remotely sensed fe oxide mapping the results indicate that the pattern of dune colour in the namib sand sea arises from the mixing of at least two distinct sources of sand a red component of high fe oxide content present as a coating on the sand grains which derives from the inland regions particularly from major embayments into the southern african escarpment and a yellow coastal component of low fe oxide content which is brought into the area by northward moving aeolian transport processes these major provenances are separated by a mixing zone between 20 km and 90 km from the coast throughout the entire length of the sand sea previous workers have also recognised a third fluvial provenance but the methodology applied here is not able to map this source as a distinct spectral component

fault tectonics of the baja california peninsula and the opening of the sea of cortez mexico abstract a detailed field analysis of neogene and quaternary faults in baja california has enabled us to reconstruct the stress pattern and the tectonic evolution of the central and southern parts of the peninsula the deformation which is related to the opening of the gulf affects the whole peninsula but decreases from east to west most observed faults normal and or dextral strike nnw sse to wnw ese their mechanisms include both strike slip and dip slip as well as intermediate motions compressional events have occurred since late neogene times but were probably of minor quantitative importance because reverse faults are rare and small the principal fault pattern includes dextral nnw sse riedel shears and n s tension faults induced by dextral strike slip along two main nw se fault zones bordering the peninsula the gulf of california to the east which is the most important and the tosco abreojos fault to the west the resulting pattern of deformation shows that the eastern part has been a complex transform extensional zone since late miocene early pliocene times

development of spatially diverse and complex dune field patterns gran desierto dune field sonora mexico the pattern of dunes within the gran desierto of sonora mexico is both spatially diverse and complex identification of the pattern components from remote sensing images combined with statistical analysis of their measured parameters demonstrate that the composite pattern consists of separate populations of simple dune patterns age bracketing by optically stimulated luminescence osl indicates that the simple patterns represent relatively short lived aeolian constructional events since 25 ka the simple dune patterns consist of i late pleistocene relict linear dunes ii degraded crescentic dunes formed at 12 ka iii early holocene western crescentic dunes iv eastern crescentic dunes emplaced at 7 ka and v star dunes formed during the last 3 ka recognition of the simple patterns and their ages allows for the geomorphic backstripping of the composite pattern palaeowind reconstructions based upon the rule of gross bedform normal transport are largely in agreement with regional proxy data the sediment state over time for the gran desierto is one in which the sediment supply for aeolian constructional events is derived from previously stored sediment ancestral colorado river sediment and contemporaneous influx from the lower colorado river valley and coastal influx from the bahia del adair inlet aeolian constructional events are triggered by climatic shifts to greater aridity changes in the wind regime and the development of a sediment supply the rate of geomorphic change within the gran desierto is significantly greater than the rate of subsidence and burial of the accumulation surface upon which it rests

properties of electrostatic aggregates and their possible presence on mars abstract experiments indicate that at the high wind velocities characteristic of portions of the martian surface sand sized particles will break down to silt and clay which will then inevitably form sand sized aggregates basalt and olivine aggregates held together by electrostatics were produced in an eolian abrasion device and their mass properties studied it was difficult to examine aggregates after formation as they separate and reform with very little handling since electrostatic binding forces are quite weak it is shown that aggregates range from 60 to more than 600 m in diameter that they generally are spheroidal in shape and become more elongate with increasing size and that they tend to be layered with the inner portions more tightly bound than outer layers after about one and one half years some aggregates lose their charge which is replaced with moisture the aggregates retain their original sizes and shapes none of the properties of electrostatic aggregates so far investigated are incompatible with the presence of these materials on mars

aeolian processes in proctor crater on mars sedimentary history as analyzed from multiple data sets 1 proctor crater is a 150 km diameter crater in noachis terra within the southern highlands of mars the analysis leading to the sedimentary history incorporates several data sets including imagery elevation composition and thermal inertia mostly from the mars global surveyor mission the resulting stratigraphy reveals that the sedimentary history of proctor crater has involved a complex interaction of accumulating and eroding sedimentation aeolian features spanning much of the history of the crater interior dominate its surface including large erosional pits stratified beds of aeolian sediment sand dunes erosional and depositional streaks dust devil tracks and small bright bed forms that are probably granule ripples long ago up to 450 m of layered sediment filled the crater basin now exposed in eroded pits on the crater floor these sediments are probably part of an ancient deposit of aeolian volcaniclastic material since then some quantity of this material has been eroded from the top layers of the strata small bright dune forms lie stratigraphically beneath the large dark dune field relative to the large dark dunes the bright bed forms are immobile although in places their orientations are clearly influenced by the presence of the larger dunes their prevalence in the crater and their lack of compositional and thermal distinctiveness relative to the crater floor suggests that these features were produced locally from the eroding basin fill dust devil tracks form during the spring and summer following a west southwesterly wind early in the spring the dust devils are largely restricted to dark patches of sand as the summer approaches dust devil tracks become more plentiful and spread to the rest of the crater floor indicating that the entire region acquires an annual deposit of dust that is revealed by seasonal dust devils the dark dunes contain few dust devil tracks suggesting that accumulated dust is swept away directly by saltation rather than by the passage of dust devils spectral deconvolution indicates that the dark dunes have infrared spectra consistent with basalt like materials the average thermal inertia calculated from thermal emission spectrometer bolometric temperatures is 277 17 j m 2 s 0 5 k 1 leading to an effective grain size of 740 170 mm which is consistent with coarse sand and within the range expected for martian sand the coarse sand that composes the large dune field may have originated from outside the crater saltating in from the southwest most of the transport pathway that delivered this sand to the dune field has since been eroded away or buried the sand was transported to the east center of the crater floor where beneath the present day dunes a 50 m high mound of sand has accumulated dune slip faces indicate a wind regime consisting of three opposing winds some of these wind directions are correlated with the orientations of dust devil tracks and bright bed forms the combination of a tall mound of sand and three opposing winds is consistent with a convergent wind regime which produces the large reversing transverse and star dunes that dominate the dune field the dark dunes have both active slip faces and seemingly inactive slip faces suggesting that the dunes vary spatially in their relative activity nevertheless the aeolian activity that has dominated the history of proctor crater still continues today index terms 5415 planetology solid surface planets erosion and weathering 5470 planetology solid surface planets surface materials and properties 5410 planetology solid surface planets

dunes of the gran desierto sand sea sonora mexico the gran desierto sand sea contains dunes of crescentic and star form in simple compound and complex varieties the dunes have developed in bimodal to complex wind regimes of intermediate energy transitions from simple through compound to complex crescentic dunes are associated with regional changes in wind regimes growth of large star dunes takes place by merging of smaller crescentic and reversing dunes from southerly directions and reworking of sand by northerly and westerly winds although wind regimes appear to be the major control of dune morphology in this sand sea there is a close correlation between the spacing of simple crescentic dunes and the grain size of the coarse 20th percentile

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