reading the climate record of the martian polar layered deposits abstract the martian polar regions have layered deposits of ice and dust the stratigraphy of these deposits is exposed within scarps and trough walls and is thought to have formed due to climate variations in the past insolation has varied significantly over time and caused dramatic changes in climate but it has remained unclear whether insolation variations could be linked to the stratigraphic record we present a model of layer formation based on physical processes that expresses polar deposition rates of ice and dust in terms of insolation in this model layer formation is controlled by the insolation record and dust rich layers form by two mechanisms 1 increased summer sublimation during high obliquity and 2 variations in the polar deposition of dust modulated by obliquity variations the model is simple yet physically plausible and allows for investigations of the climate control of the polar layered deposits pld we compare the model to a stratigraphic column obtained from the north polar layered deposits npld fishbaugh k e hvidberg c s byrne s russel p s herkenhoff k e winstrup m kirk r 2010a geophys res lett 37 l07201 and show that the model can be tuned to reproduce complex layer sequences the comparison with observations cannot uniquely constrain the pld chronology and it is limited by our interpretation of the observed stratigraphic column as a proxy for npld composition we identified however a set of parameters that provides a chronology of the npld tied to the insolation record and consistently explains layer formation in accordance with observations of npld stratigraphy this model dates the top 500 m of the npld back to 1 million years with an average net deposition rate of ice and dust of 0 55 mm a 1 the model stratigraphy contains a quasi periodic 30 m cycle similar to a previously suggested cycle in brightness profiles from the npld laskar j levrard b mustard f 2002 nature 419 375 377 milkovich s head j w 2005 j geophys res 110 but here related to half of the obliquity cycles of 120 and 99 kyr and resulting from a combination of the two layer formation mechanisms further investigations of the non linear insolation control of pld formation should consider data from other geographical locations and include radar data and other stratigraphic datasets that can constrain the composition and stratigraphy of the npld layers

orbital forcing of the martian polar layered deposits since the first images of polar regions on mars revealed alternating bright and dark layers there has been speculation that their formation might be tied to the planet s orbital climate forcing1 2 3 4 but uncertainties in the deposition timescale exceed two orders of magnitude estimates based on assumptions of dust deposition ice formation and sublimation and their variations with orbital forcing suggest a deposition rate of 10 3 to 10 2 cm yr 1 refs 5 6 whereas estimates based on cratering rate result in values as high as 0 1 to 0 2 cm yr 1 ref 7 here we use a combination of high resolution images of the polar layered terrains8 high resolution topography9 and revised calculations of the orbital and rotational parameters of mars to show that a correlation exists between ice layer radiance as a function of depth obtained from photometric data of the images of the layered terrains and the insolation variations in summer at the martian north pole similar to what has been shown for palaeoclimate studies of the earth10 11 12 for the best fit between the radiance profile and the simulated insolation parameters we obtain an average deposition rate of 0 05 cm yr 1 for the top 250 m of deposits on the ice cap of the north pole of mars

surface unit characterization of the mauna ulu flow field kilauea volcano hawai i using integrated field and remote sensing analyses abstract investigation of surface units in the mauna ulu flow field kilauea volcano hawai i was conducted through field and remote sensing analyses recently acquired advanced spaceborne thermal emission and reflection radiometer aster and master modis aster airborne simulator datasets which cover the visible through thermal wavelength region have been analyzed and correlated with a field based characterization of mauna ulu flow unit surfaces field observations were made of unit morphologies decimeter to decameter scale as well as small scale millimeter to centimeter scale surface textures estimates were made of the extent of surface crust spallation as well as the abundance of vesicles and phenocrysts on the surface crust and spallation surfaces the field based characteristics were compared with remote sensing data including visible and near infrared reflectance spectra thermal infrared emissivity spectra and emissivity derived small scale roughness visible wavelength characteristics are controlled primarily by color luster and decimeter to meter scale surface irregularities whereas thermal wavelength characteristics are primarily controlled by the abundance of small scale roughness elements such as vesicles although individual data pixels are not of sufficient resolution to identify typical individual lava flow units using point spectra mean spectra allow characterization of unit surface crusts flow unit morphologies and surface textures are related to differences in emplacement and post emplacement modification of a a and pahoehoe lobes pahoehoe surface properties reflect the flow regime during emplacement and the history of cooling degassing and crystal formation settling the nature of pahoehoe surface crusts indicates that within the wide range of emplacement conditions expressed within the flow field two sets of conditions are dominant producing a bronzy smooth crust or a dark rough crust the former makes up the majority of the pahoehoe surfaces and reflects minimal cooling and degassing prior to emplacement whereas the latter reflects cooling and crystallization during storage within the flow field this study provides a detailed characterization of mauna ulu surface units and presents an integrated field and remote sensing approach to mapping and interpreting the emplacement of lava flow fields

a search for basaltic to intermediate glasses on mars assessing martian crustal mineralogy multiple datasets have demonstrated that the crust of mars is fundamentally basaltic however spectral libraries used to interrogate thermal infrared spectra of martian dark regions through spectral deconvolution have heretofore lacked mafic glasses despite the importance of amorphous phases or phases with amorphous like spectral signatures in martian mineralogy to establish the presence and importance of basaltic to intermediate glasses in martian lithologies we created five such glasses obtained their thermal infrared spectra and included the spectra in a library used to deconvolve nine regional thermal emission spectrometer spectra from mars we employed the nonnegative least squares nnls deconvolution method which yields deconvolved phase abundances and the uncertainties associated with those abundances the basaltic to intermediate glasses do not appear in the deconvolution solutions indicating they are not globally or regionally important phases because martian igneous or impact processes are capable of basaltic to intermediate glass formation the lack of such glasses in the deconvolved mineralogies suggests either the glasses did not form in detectable quantities or they or their signatures have been removed the masking or replacement of basaltic to intermediate glasses through alteration is supported by the appearance in the deconvolution solutions of amorphous phases e g silica rich glasses opal or phases with amorphous like spectral signatures e g clays zeolites that commonly form through aqueous alteration of mafic glasses the glasses may still be important to local scale thermal infrared studies given the basaltic nature of mars and the variety of local scale lithologies detected by various missions the regional mineralogies derived from the nnls deconvolution analysis divide into five statistically separable groups which provide insight into regional trends in mineralogy

stratigraphy of the north polar layered deposits of mars from high resolution topography nasa earth and space science fellowship nnx13ao55h nasa s mars reconnaissance orbiter project hirise

spaceborne observations of the 2000 bezymianny kamchatka eruption the integration of high resolution aster data into near real time monitoring using avhrr abstract since its launch in december 1999 the advanced spaceborne thermal emission and reflection radiometer aster instrument has been observing over 1300 of the world s volcanoes during the day and night and at different times of the year at the onset of an eruption the temporal frequency of these regularly scheduled observations can be increased to as little as 1 3 days at higher latitudes however even this repeat time is not sufficient for near real time monitoring which is on the order of minutes to hours using poorer spatial resolution 1 km pixel instruments the eruption of bezymianny volcano kamchatkan peninsula russia in march 2000 was detected by the alaska volcano observatory avo and also initiated an increased observation frequency for aster a complete framework of the eruptive cycle from april 2000 to january 2001 was established with the advanced very high resolution radiometer avhrr data used to monitor the large eruptions and produce the average yearly background state for the volcano twenty nearly cloud free aster scenes 2 days and 18 nights show large thermal anomalies covering tens to hundreds of pixels and reveal both the actively erupting and restive background state of the volcano aster short wave infrared swir and thermal infrared tir data were also used to validate the recovered kinetic temperatures from the larger avhrr pixels as well as map the volcanic products and monitor the thermal features on the summit dome and surrounding small pyroclastic flows these anomalies increase to greater than 90 c prior to a larger eruption sequence in october 2000 in addition aster has the first multispectral spaceborne tir capability which allowed for the modeling of micrometer scale surface roughness vesicularity on the active lava dome where coupled with ongoing operational monitoring programs like those at avo aster data become extremely useful in discrimination of small surface targets in addition to providing enhanced volcanic mapping capabilities

a global view of martian surface compositions from mgs tes thermal emission spectrometer tes data from the mars global surveyor mgs are used to determine compositions and distributions of martian low albedo regions two surface spectral signatures are identified from low albedo regions comparisons with spectra of terrestrial rock samples and deconvolution results indicate that the two compositions are a basaltic composition dominated by plagioclase feldspar and clinopyroxene and an andesitic composition dominated by plagioclase feldspar and volcanic glass the distribution of the two compositions is split roughly along the planetary dichotomy the basaltic composition is confined to older surfaces and the more silicic composition is concentrated in the younger northern plains

spectral characterization of igneous rocks in the 8 to 12 μm region variation in the spectral response of silicates in the thermal infrared tir from 8 to 12 m is the foundation for potentially important applications in the lithologic characterization of terrestrial and extraterrestrial surfaces the purpose of this study is to elucidate the crystallo chemical basis for the variation in spectral behavior in terms which may be useful in remote sensing this has led to the definition of a new parameter scfm which is defined as the ratio sio2 sio2 cao feo mgo in minerals and rocks this parameter reflects the degree of depolymerization of the silica tetrahedra and is therefore highly correlated with the structure of tir reflectance spectra of major silicate minerals in both fine and coarse grained igneous rocks it is also a good numerical descriptor of igneous rock composition thus scfm is proposed as a very useful determinant for spectral identification of igneous rocks the scfm parameter was used to assess the effect of variations in location number and width of bands in discriminating rock composition an unfortunate ambiguity exists in the use of the term band which in spectroscopy indicates a feature in a spectrum and in remote sensing signifies a specific wavelength increment or channel the latter definition is used in this paper spectra of coarse particulate mineral and solid rock samples were acquired in the laboratory a regression analysis of bands varying in width from 0 2 to 1 4 m versus scfm results in coefficients of determination correlation coefficients r2 ranging from 0 88 for two 1 2 m wide bands to 0 97 for seven 0 2 m wide bands deletion of bands in the ozone absorption region 9 4 10 2 m results in a decrease in r2 by only 0 01 stimulation of system noise by addition of 5 random counts to the bands decreases r2 by only 0 03 because spectra structure is modified by weathering alteration and texture of the samples the validity of these results is limited to fresh igneous rocks with this constraint it is concluded that accurate spectral identification of igneous rock composition is not greatly affected by bandwidth or system noise it is the overall spectral envelope rather than the fine structure in the tir which contains most of the information diagnostic of igneous rock composition this permits design of remote sensing systems with broad bands and corresponding higher signal to noise which can be traded off against the important requirement for higher spatial resolution

global geologic context for rock types and surface alteration on mars petrologic interpretations of thermal emission spectra from mars orbiting spacecraft indicate the widespread occurrence of surfaces having basaltic and either andesitic or partly altered basalt compositions global concentration of ice rich mantle deposits and near surface ice at middle to high latitudes and their spatial correlation with andesitic or partly altered basalt materials favor the alteration hypothesis we propose the formation of these units through limited chemical weathering from basalt interactions with icy mantles deposited during periods of high obliquity alteration of sediments in the northern lowlands depocenter may have been enhanced by temporary standing bodies of water and ice

models of climate cycles recorded in martian polar layered deposits abstract layered strata observed in orbital images of polar sedimentary terrains on mars have been hypothesized to contain information about recent variations in the martian climate celestial mechanicians have determined that mars has experienced large amplitude quasi periodic variations in obliquity and eccentricity planetary meteorologists have inferred that the resulting changing patterns of solar heating must have had dramatic effects on martian climate accordingly it might be possible to link the known recent history of orbit axial variations with the physical characteristics of the most recently deposited strate determined from orbital imagery our paper explores that possibility quantitatively for various models of the formation of the polar layered deposits and the layering developed within them we modeled the formation of polar layered deposits during the past 10 my for two general classes of model uniform deposition rate udr models assume that the major constituent of the layered deposits is deposited at a uniform rate and that layering is established by climate induced variations in the concentration of a minor constituent climate modulated deposition rate cmdr models assume that the deposition rate of the major constituent is controlled by climate and that layer boundaries correspond to intervals of nondeposition in both models abrupt changes in deposition regime occur when a function of the orbit axial parameters crosses a threshold value detailed physical mechanisms for the control of sedimentation by orbit axial variations were developed for two specific models of the cmdr type in one model the deposits are assumed to be primarily composed of dust in the other they are assumed to be predominantly water ice we calculated the times at which abrupt changes in deposition regime occur and determined the relative thicknesses of successive layers which can be compared against layer thicknesses made from orbital imagery in all these models obliquity variations exert the dominant influence on the sequential variations in layer thickness although eccentricity and precession index longitude of perihelion may take recognizable contributions as well the layer patterns for the north and south polar deposits are identical for the dust model and only slightly different for the ice model but this is at least partly a consequence of simplifying assumptions the sequential variation in layer thickness is also very sensitive to those model parameters which control the fraction of time for which deposition occurs when the climate threshold for deposition is low deposition occurs a large fraction of the total time and characteristic patterns form with one thick layer and a number of much thinner ones such patterns would be easily recognized in photogeological measurements of layer thickness when the threshold for deposition lies in the mid range with respect to excursions of the climate function deposition occurs approximately half of the time and there is only slight modulation of layer thickness when the threshold for deposition is high deposition occurs only a small fraction of the total time and groups of layers form which are separated form other groups by long periods of nondeposition the stratigraphic unconformities that separate groupings of five to ten layers in the polar deposits may indicate that the martian polar region has experienced such a depositional history the feasibility of using these model results to verify the theory of climate control of polar stratigraphy on mars and to gain additional insights into the significant processes is considered the stratigraphy issues raised here are also explored in the context of recent work on the interpretation of stratigraphy of ocean margins from this comparison there emerge some valuable insights into the stratigraphic effects of periods of nondeposition and the uncertaintiesin interpreting images of exposed polar strata on mars

thermal infrared reflectance and emission spectroscopy of quartzofeldspathic glasses 1 this investigation seeks to better understand the thermal infrared tir spectral characteristics of naturally occurring amorphous materials through laboratory synthesis and analysis of glasses because spectra of glass phases differ markedly from their mineral counterparts examination of glasses is important to accurately determine the composition of amorphous surface materials using remote sensing datasets quantitatively characterizing tir 5 25 m spectral changes that accompany structural changes between glasses and mineral crystals provides the means to understand natural glasses on earth and mars a suite of glasses with compositions analogous to common terrestrial volcanic glasses was created and analyzed using tir reflectance and emission techniques documented spectral characteristics provide a basis for comparison with tir spectra of other amorphous materials glasses clays etc our results provide the means to better detect and characterize glasses associated with terrestrial volcanoes as well as contribute toward understanding the nature of amorphous silicates detected on mars

a procedure for testing the significance of orbital tuning of the martian polar layered deposits layered deposits of dusty ice in the martian polar caps have been hypothesized to record climate changes driven by orbitally induced variations in the distribution of incoming solar radiation attempts to identify such an orbital signal by tuning a stratigraphic sequence of polar layered deposits plds to match an assumed forcing introduce a risk of identifying spurious matches between unrelated records we present an approach for evaluating the significance of matches obtained by orbital tuning and investigate the utility of this approach for identifying orbital signals in the mars plds using a set of simple models for ice and dust accumulation driven by insolation we generate synthetic pld stratigraphic sequences with nonlinear time depth relationships we then use a dynamic time warping algorithm to attempt to identify an orbital signal in the modeled sequences and apply a monte carlo procedure to determine whether this match is significantly better than a match to a random sequence that contains no orbital signal for simple deposition mechanisms in which dust deposition rate is constant and ice deposition rate varies linearly with insolation we find that an orbital signal can be confidently identified if at least 10 of the accumulation time interval is preserved as strata addition of noise to our models raises this minimum preservation requirement and we expect that more complex deposition functions would generally also make identification more difficult in light of these results we consider the prospects for identifying an orbital signal in the actual pld stratigraphy and conclude that this is feasible even with a strongly nonlinear relationship between stratigraphic depth and time provided that a sufficient fraction of time is preserved in the record and that ice and dust deposition rates vary predictably with insolation independent age constraints from other techniques may be necessary for example if an insufficient amount of time is preserved in the stratigraphy

north polar cap of mars polar layered deposit characterization and identification of a fundamental climate signal of the cap 6 10 5 km 2 in the 13 images analyzed to date 3 assessment of geometric relationships shows that layers are not horizontal but rather have an apparent dip of approximately 0 5 degrees we interpret these results as follows 1 the fundamental 30 m signal is interpreted as a climate signal that may correspond to a 51 kyr insolation cycle 2 the lateral correlation and broad distribution of these layer sequences strongly imply that layer accumulation processes are widespread across the cap rather than confined within a single trough or region 3 local to regional variability in individual layer thicknesses and thus accumulation and sublimation rates is typically less than a factor of 2 5 providing the ability to study regional trends but often making it difficult to correlate visually the vertical sequences in individual cores finally initial examination of layers located deeper in the stratigraphic sequence within the north polar cap than the 300 m thick zone 1 provides evidence for a unit less than 100 m thick zone 2 in which the fundamental 30 m sequence is not detected we interpret this as a deposit having formed during a recent high obliquity phase of mars during which time polar volatiles underwent mobilization and were transport equatorward leaving a polar lag of dust rich material the most recent ice age 0 5 2 ma offers a plausible candidate for this period of ice cap removal and lag deposit formation an underlying zone 3 200 m contains a dominant 35 m signal and a lowermost zone 4 200 m contains multiple signals but no dominant one together these four zones represent 800 m of vertical stratigraphic section about one fourth of the total thickness of the cap these findings support earlier interpretations that orbital parameter variations could cause significant erosion and possibly complete removal of the polar caps the interpreted crater retention ages of the layered terrain are consistent with the correlations and vertical sequences described here suggesting that the polar caps wax and wane throughout geological history depending on the evolution of orbital parameters definition of the 30 m unit signal holds promise for determining 1 the detailed origin of individual layer types 2 the nature of deposition and sublimation processes and their relation to insolation geometry across the polar cap and 3 correlation with and comparison to the south polar layered terrain record

first high resolution stratigraphic column of the martian north polar layered deposits 1 this study achieves the first high spatial resolution layer scale measured stratigraphic column of the martian north polar layered deposits using a 1m posting dem the marker beds found throughout the upper north polar layered deposits range in thickness from 1 6 m 16 0 m 1 4 m and 6 of 13 marker beds are separated by 25 35 m thin layer sets have average layer separations of 1 6 m these layer separations may account for the spectral power peaks found in previous brightness profile analyses marker bed layer thicknesses show a weak trend of decreasing thickness with depth that we interpret to potentially be the result of a decreased accumulation rate in the past for those layers however the stratigraphic column reveals that a simple rhythmic or bundled layer sequence is not immediately apparent throughout the column implying that the relationship between polar layer formation and cyclic climate forcing is quite complex

meter scale morphology of the north polar region of mars mars north pole is covered by a dome of layered ice deposits detailed 30 centimeters per pixel images of this region were obtained with the high resolution imaging science experiment on board the mars reconnaissance orbiter mro planum boreum basal unit scarps reveal cross bedding and show evidence for recent mass wasting flow and debris accumulation the north polar layers themselves are as thin as 10 centimeters but appear to be covered by a dusty veneer in places which may obscure thinner layers repetition of particular layer types implies that quasi periodic climate changes influenced the stratigraphic sequence in the polar layered deposits informing models for recent climate variations on mars

spectral evidence for weathered basalt as an alternative to andesite in the northern lowlands of mars mineral abundances derived from the analysis of remotely sensed thermal emission data from mars have been interpreted to indicate that the surface is composed of basalt surface type 1 and andesite surface type 2 1 the global distribution of these rock types is divided roughly along the planetary dichotomy which separates ancient heavily cratered crust in the southern hemisphere basalt from younger lowland plains in the north andesite 1 but the existence of such a large volume of andesite is difficult to reconcile with our present understanding of the geological evolution of mars here we reinterpret martian surface rock lithologies using mineral abundances from previous work1 and new mineralogies derived from a spectral end member set representing minerals common in unaltered and low temperature aqueously altered basalts our results continue to indicate the dominance of unaltered basalt in the southern highlands but reveal that the northern lowlands can be interpreted as weathered basalt as an alternative to andesite the coincidence between locations of such altered basalt and a suggested northern ocean basin implies that lowland plains material may be composed of basalts weathered under submarine conditions or weathered basaltic sediments transported into this depocentre

detailed stratigraphy and bed thickness of the mars north and south polar layered deposits the mars polar layered deposits pld likely hold an extensive record of recent climate during a period of high amplitude orbit and obliquity cycles previous work has detected limited evidence for orbital signatures within pld stratigraphy but data from the high resolution imaging science experiment hirise permit renewed analysis of pld stratigraphy at sub meter scale topography derived from hirise images using stereogrammetry resolves beds previously detectable only as alternating light and dark bands in visible images we utilize these data to measure the thickness of individual beds within the pld corrected for non horizontal bed orientation stratigraphic columns and bed thickness profiles are presented for two sites within the npld and show several sets of finely bedded units 1 2 m thick isolated marker beds 3 4 m thick and undifferentiated sections bed thickness measurements for three sites within the spld exhibit only one bed type based on albedo and morphology and bed thicknesses have a larger mean and variance compared to measurements for the npld power spectra of brightness and slope derived along the measured stratigraphic sections confirm the regularity of npld fine bed thickness and the lack of a dominant spld bed thickness the regularity of fine bed thickness of the npld is consistent with quasiperiodic bed formation albeit with unknown temporal period the spld thickness measurements show no such regularity

mars north polar deposits stratigraphy age and geodynamical response the shallow radar sharad on the mars reconnaissance orbiter has imaged the internal stratigraphy of the north polar layered deposits of mars radar reflections within the deposits reveal a laterally continuous deposition of layers which typically consist of four packets of finely spaced reflectors separated by homogeneous interpacket regions of nearly pure ice the packet interpacket structure can be explained by approximately million year periodicities in mars obliquity or orbital eccentricity the observed 100 meter maximum deflection of the underlying substrate in response to the ice load implies that the present day thickness of an equilibrium elastic lithosphere is greater than 300 kilometers alternatively the response to the load may be in a transient state controlled by mantle viscosity both scenarios probably require that mars has a subchondritic abundance of heat producing elements

north polar stratigraphy and the paleo erg of mars an accurate self consistent way of coregistering the imaging and topographic data sets of the mars global surveyor mission was developed and used to begin a stratigraphic analysis of the northern polar region a distinct change in the layering style exists at a definite stratigraphic horizon near the base of the north polar layered deposits occurrences of the contact between two distinct layered units can be mapped hundreds of kilometers apart at nearly the same mars orbiter laser altimeter mola elevation the lower layered unit has a consistent association with sand dunes leading to the conclusion that it is an eroding sand rich deposit that predates most of the overlying north polar layered deposits which exhibits the expected features of a dust ice mixture these results suggest that an areally extensive erg was in existence before the present ice cap and that the present circumpolar erg is likely composed of material reworked from this older deposit the volume of this lower unit is estimated to be on the order of 10 5 km 3 the presence of this deposit implies that there existed a period in mars history when there was no icy polar cap a dramatic climatic change leading to the deposition of the upper layered icy unit in the present day polar layered deposits represents a major event in mars history however owing to uncertainties in the mechanics of layered deposits formation such an event cannot be dated at this time

effects of pure silica coatings on thermal emission spectra of basaltic rocks considerations for martian surface mineralogy 1 on mars silica derived from chemical weathering could precipitate to coat rocks and particles we suggest that rock coatings of secondary amorphous silica may account for a widespread martian surface spectral unit previously modeled as andesite or weathered basalt in a laboratory study we investigated the effects of synthetic silica coatings on thermal infrared tir spectroscopic measurements secondary amorphous silica is spectrally similar to silicate glass and clay spectra used in previous spectroscopic models silica coating and substrate spectra combine nonlinearly to produce a composite spectrum of a coated rock silica coatings 10 m thick effectively mask the spectral contribution of a silicate substrate therefore the capability of volumetrically small amounts of silica present as thin coatings on rocks should be considered when seeking explanations for spectral variability of martian surface materials

laboratory thermal emission spectroscopy of shocked basalt from lonar crater india and implications for mars orbital and sample data 1 whereas the thermal infrared tir spectra of specific minerals and or igneous and metamorphic rocks have been compared to data of the martian surface tir data of the impactite products of the shock metamorphism of basalt have not been examined in detail the effects of shock on the thermal infrared spectrum of deccan basalt are described here sample collection at lonar crater india yielded four classes of shocked basalt classes 1 2 4 and 5 spectral features attributed to labradorite in tir spectrum of unshocked deccan basalt are absent in the spectrum of class 2 shocked basalt petrography confirms that labradorite has been replaced by diaplectic glass maskelynite the tir spectrum of class 2 shocked basalt is nearly identical to that of the los angeles shergottite the addition of experimentally shocked plagioclase feldspars as tir end members improves fits and lowers rms errors for the deconvolution of the tir spectrum of the maskelynite bearing impactite and the correct mineralogy is chosen to within 5 class 4 shocked basalt contains vesiculated plagioclase glass due to more heat and highly fractured augites two class 5 spectral types have primary si o stretching vibrations at lower wave numbers than si and si k glass end members commonly used in analyses of tir data agreeing with lower sio2 abundances 50 determined from two techniques at least three differences in spectral features exist between the two class 5 spectral types that we attribute to incomplete melting in the class 5a samples based on comparison to the class 4 spectrum these samples and their tir spectra represent excellent analogs for martian shocked basalt and new lithologic end members for use in spectral libraries used to analyze tir data from mars

context camera investigation on board the mars reconnaissance orbiter 1 the context camera ctx on the mars reconnaissance orbiter mro is a facility instrument i e government furnished equipment operated by a science team not responsible for design and fabrication designed built and operated by malin space science systems and the mro mars color imager team marci ctx will 1 provide context images for data acquired by other mro instruments 2 observe features of interest to nasa s mars exploration program e g candidate landing sites and 3 conduct a scientific investigation led by the marci team of geologic geomorphic and meteorological processes on mars ctx consists of a digital electronics assembly a 350 mm f 3 25 schmidt type telescope of catadioptric optical design with a 5 7 field of view providing a 30 km wide swath from 290 km altitude and a 5000 element ccd with a band pass of 500 700 nm and 7 m pixels giving 6 m pixel spatial resolution from mro s nearly circular nearly polar mapping orbit raw data are transferred to the mro spacecraft flight computer for processing e g data compression before transmission to earth the ground data system and operations are based on 9 years of mars global surveyor mars orbiter camera on orbit experience ctx has been allocated 12 of the total mro data return or about 3 terabits for the nominal mission this data volume would cover 9 of mars at 6 m pixel but overlapping images for stereo mosaics and observation of changes and meteorological events will reduce this area ctx acquired its first instrument checkout images of mars on 24 march 2006

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

multispectral thermal infrared mapping of the 1 october 1988 kupaianaha flow field kilauea volcano hawaii multispectral thermal infrared radiance measurements of the kupaianaha flow field were acquired with the nasa airborne thermal infrared multispectral scanner tims on the morning of 1 october 1988 the tims data were used to map both the temperature and emissivity of the surface of the flow field the temperature map depicted the underground storage and transport of lava the presence of molten lava in a tube or tumulus resulted in surface temperatures that were at least 10 c above ambient the temperature map also clearly defined the boundaries of hydrothermal plumes which resulted from the entry of lava into the ocean the emissivity map revealed the boundaries between individual flow units within the kupaianaha field in general the emissivity of the flows varied systematically with age but the relationship between age and emissivity was not unique distinct spectral anomalies indicative of silica rich surface materials were mapped near fumaroles and ocean entry sites this apparent enrichment in silica may have resulted from an acid induced leaching of cations from the surfaces of glassy flows such incipient alteration may have been the cause for virtually all of the emissivity variations observed on the flow field the spectral anomalies representing areas where the acid attack was most intense

recent and episodic volcanic and glacial activity on mars revealed by the high resolution stereo camera the large area coverage at a resolution of 10 20 metres per pixel in colour and three dimensions with the high resolution stereo camera experiment on the european space agency mars express mission has made it possible to study the time stratigraphic relationships of volcanic and glacial structures in unprecedented detail and give insight into the geological evolution of mars here we show that calderas on five major volcanoes on mars have undergone repeated activation and resurfacing during the last 20 per cent of martian history with phases of activity as young as two million years suggesting that the volcanoes are potentially still active today glacial deposits at the base of the olympus mons escarpment show evidence for repeated phases of activity as recently as about four million years ago morphological evidence is found that snow and ice deposition on the olympus construct at elevations of more than 7 000 metres led to episodes of glacial activity at this height even now water ice protected by an insulating layer of dust may be present at high altitudes on olympus mons

shocked plagioclase signatures in thermal emission spectrometer data of mars abstract the extensive impact cratering record on mars combined with evidence from snc meteorites suggests that a significant fraction of the surface is composed of materials subjected to variable shock pressures pressure induced structural changes in minerals during high pressure shock events alter their thermal infrared spectral emission features particularly for feldspars in a predictable fashion to understand the degree to which the distribution and magnitude of shock effects influence martian surface mineralogy we used standard spectral mineral libraries supplemented by laboratory spectra of experimentally shocked bytownite feldspar johnson j r horz f christensen p lucey p g 2002b j geophys res 107 e10 doi 10 1029 2001je001517 to deconvolve thermal emission spectrometer tes data from six relatively large 50 km impact craters on mars we used both tes orbital data and tes mosaics emission phase function sequences to study local and regional areas near the craters and compared the differences between models using single tes detector data and 3 2 detector averaged data inclusion of shocked feldspar spectra in the deconvolution models consistently improved the rms errors compared to models in which the spectra were not used and resulted in modeled shocked feldspar abundances of 15 in some regions however the magnitudes of model rms error improvements were within the noise equivalent rms errors for the tes instrument hamilton v personal communication this suggests that while shocked feldspars may be a component of the regions studied their presence cannot be conclusively demonstrated in the tes data analyzed here if the distributions of shocked feldspars suggested by the models are real the lack of spatial correlation to crater materials may reflect extensive aeolian mixing of martian regolith materials composed of variably shocked impact ejecta from both local and distant sources

impact melts and glasses on mars 1 dark mobile materials on mars are widely considered to be volcanically derived windblown particulates such a conclusion is consistent with the large volcanic edifices on mars and the assumption that a volatile rich crust would not favor significant impact melt generation several post viking discoveries however provide new perspectives for reconsidering alternative origins not only for some of the mobile dark veneers but also certain materials at the pathfinder and viking landing sites first certain dark materials on mars do not exhibit the expected mafic absorption features in their reflectance spectra second the pathfinder mission revealed unexpected feldspathic compositions of vesicular blocks that lead to a preliminary conclusion that they represent andesites or basaltic andesites rather than basalts third recent discoveries of holocene to miocene impacts in argentine loessoid deposits provide new insights for the nature of melts generated from eolian sediments fourth global dispersal of impact melt products are now recognized in the terrestrial record throughout the cenozoic consequently the generation and preservation of impact glass on mars should be reconsidered possible occurrences include possible tektite like strewnfields downrange from recent oblique impacts dark avalanches emerging from backwasting cliffs of easily eroded unconformable deposits global dispersal of glassy ejecta from hesperian and amazonian craters of chicxulub scale and dark mobile veneers emerging from noachian craters we propose that the mobile dark materials comprising many of the named features of mars as well as some blocks at the pathfinder viking landing sites may represent impact melt products

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

eolian dynamics and sediment mixing in the gran desierto mexico determined from thermal infrared spectroscopy and remote sensing data the gran desierto dune field is only partially composed of quartz rich sands from the ancestral colorado river local sources have been previously underestimated as a major source of sand because previous remote sensing studies were limited in their capability to detect silicate minerals compositions of sands were evaluated in this study using a combination of laboratory thermal emission spectroscopy and thermal remote sensing data acquired from the advanced spaceborne thermal emission and reflection radiometer aster instrument the spatial interpolation of sample compositions allowed visualization of the sand transport pathways from feldspar rich local sources by revealing gradients of composition between the dune field and surrounding local sources the laboratory data were comparable to the remote sensing retrievals of quartz and feldspar abundance the mineralogical maturity of the desierto dunes could be determined by the quartz feldspar ratio therefore providing a context for understanding the provenance of the gran desierto in relation to other mojave and sonoran dune fields the composition of a previously undescribed group of dunes east of the pinacate the sonoyta dunes was measured as higher in potassium feldspar relative to the rest of the dune field the composition of sonoyta dunes is characteristic of other mojave dune fields which are more isolated near local feldspar rich sources south of the pinacate quartz rich sand from the west admixes with feldspar rich sand from the sonoyta dunes to the east the northern margin of the gran desierto is similarly enriched in feldspar from alluvial fans and the coastal sand is influenced by carbonate sand that does not appear to survive transport to the inland dunes

martian north polar layered deposits stratigraphy implications for accumulation rates and flow 1 we have used mars orbiter camera moc images and mars observer laser altimeter mola data to correlate specific layers within the upper 500 m of the martian north polar layered deposits in many troughs using these correlation results we derive relative accumulation rates across the polar layered deposits and through time we identify two major layer sequences one lying stratigraphically above the other each consistent with an overall curving downward layer structure with shallow slopes but with significant localized variations in layer height major disruptions of stratigraphy such as angular unconformities do not appear within the correlated layer sequences on local and broad scales each layer sequence exhibits a different relative accumulation rate pattern indicating that this rate has not remained constant through time and has been affected by localized processes the overall pattern of the lower layer sequence is similar to that of a classic terrestrial ice sheet with a decreasing relative accumulation rate away from the center of the polar layered deposits southward the upper layer sequence exhibits no obvious overall trends we also compare our correlation results to predictions of the effects of simple ice flow on layer structure finding that mass balance patterns have overprinted any effects of large scale ice flow flow has not been significant compared to mass balance in forming the overall structure of the correlated layers

relative dating of hawaiian lava flows using multispectral thermal infrared images a new tool for geologic mapping of young volcanic terranes the weathering of hawaiian basalts in arid and semiarid environments is accompanied by change in their thermal infrared emittance spectra the spectral differences can be measured and mapped with multispectral imaging systems the differences appear to be related to the degree of development preservation and alteration of glassy crusts the oxidation of iron and the accretion of silica rich surface veneers because the measurements are quantitative and in image format they are useful for estimating relative ages in geologic mapping of lava flows in hawaii this technique is most diagnostic for distinguishing among sparsely vegetated flows less than 1 5 ka in age

discrimination of glass and phyllosilicate minerals in thermal infrared data 1 thermal infrared spectra of glasses and phyllosilicates have similar shapes leading to a proposed ambiguity in deconvolution results we quantify the spectral separability of these two classes using discriminant analysis and linear deconvolution we apply the deconvolution technique to single spectra and two and four component mixtures missing end members result in quantifiable uncertainties between modeled abundances of glasses and phyllosilicates mixtures containing silica k2o glass are susceptible to overestimating phyllosilicates with minimal increases in root mean square error if the silica k2o glass spectrum is not present in the end member set missing phyllosilicate end members are likely to be modeled as combinations of other phyllosilicates rather than glasses with saponite nontronite and halloysite showing the highest uncertainties empirically 15 of the total glass plus phyllosilicate abundance incorporates all uncertainties in derived glass abundance if the glass in the mixture is in the end member set if the glass in the mixture is excluded from the end member set these uncertainties increase to 65 four component mixtures show that glasses and phyllosilicates act as a two component mixing system but can induce small uncertainties in other components applying the maximum derived uncertainties to deconvolutions of surface type 2 measured by the mars global surveyor thermal emission spectrometer we find that silica k2o glass abundance is above the instrument detection limit and a likely component of the surface pure silica glass a proposed amorphous weathering product is the least likely candidate for confusion with phyllosilicates and its noninclusion in models of martian spectra suggests it likely is not a component of the martian surface

the polar deposits of mars the tantalizing prospect of a readable record of martian climatic variations has driven decades of work toward deciphering the stratigraphy of the martian polar layered deposits and understanding the role of the residual ice caps that cover them spacecraft over the past decade have provided a massive infusion of new data into mars science polar science has benefited immensely due to the near polar orbits of most of the orbiting missions and the successful landing of the phoenix spacecraft in the northern high latitudes topographic thermal radar hyperspectral and high resolution imaging data are among the datasets that have allowed characterization of the stratigraphy of the polar layered deposits in unprecedented detail additionally change within the residual ice caps has been monitored with spacecraft instruments for several years these new data have provided a golden opportunity to understand the interplay between the martian orbit climate and polar ice

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

origin and characteristics of the mars north polar basal unit and implications for polar geologic history building upon previous studies we have used mars orbiter camera and mars orbiter laser altimeter data to characterize in detail the newly discovered north polar basal unit lying stratigraphically between the polar layered deposits from which it is likely separated by an unconformity and the vastitas borealis formation this unit has introduced new complexity into north polar stratigraphy and has important implications for polar history exposures of the basal unit in olympia planitia and chasma boreale reveal relatively dark layers which exhibit differential erosion eroded primarily by wind the basal unit may be the major if not sole source for the north polar dunes and ergs and has contributed material to the lower polar cap layers we investigate four possible origins for the basal unit outflow channel oceanic deposits basal ice paleopolar deposits and eolian deposits the patchy layering within the unit its likely sandy grain size and presence only in the north polar basin suggest that it is primarily an eolian deposit supporting byrne and murray s 2002 earlier conclusion this implies that at some time during the early to late amazonian migrating sand was mixed with water ice forming a relatively dark sandy deposit during this time either no classic polar layered deposits were forming or smaller caps were growing and shrinking possibly adding material to the basal unit

sharad sounding radar on the mars reconnaissance orbiter 1 sharad shallow radar is a sounding radar provided by agenzia spaziale italiana asi as a facility instrument on the mars reconnaissance orbiter mission its 20 mhz center frequency and 10 mhz bandwidth complement the lower frequency relatively narrower bandwidth capability of the marsis sounding radar a joint italian u s team has guided the experiment development and is responsible for data analysis and interpretation the radar transmits signals at a 700 hz pulse repetition frequency prf and collects reflections from both the surface and near subsurface of mars vertical and horizontal resolutions are respectively 15 m free space and 3 6 km cross track by 0 3 1 km along track the scientific objective of sharad is to map in selected locales dielectric interfaces to at least several hundred meters depth in the martian subsurface and to interpret these results in terms of the occurrence and distribution of expected materials including competent rock soil water and ice a signal to noise ratio of 50 db for a specular surface return is achieved with 10 w of radiated power by using range and azimuth focusing in ground data processing preprocessed data as well as range and azimuth focused data will be formatted according to planetary data system pds standards and be made available from the asi science data center asdc and from the geosciences node of the planetary data system pds important targets for sharad include the polar layered deposits sedimentary stacks especially in terra meridiani buried channel systems buried impact craters volcanic complexes and shallow ice deposits in equilibrium with the atmosphere

observational evidence for an active surface reservoir of solid carbon dioxide on mars high resolution images of the south polar residual cap of mars acquired in 1999 and 2001 show changes in the configuration of pits intervening ridges and isolated mounds escarpments have retreated 1 to 3 meters in 1 martian year changes that are an order of magnitude larger than can be explained by the sublimation of water ice but close to what is expected for sublimation of carbon dioxide ice these observations support a 35 year old conjecture that mars has a large surface reservoir of solid carbon dioxide the erosion implies that this reservoir is not in equilibrium with the present environment and that global climate change is occurring on mars

evaluating the meaning of layer in the martian north polar layered deposits and the impact on the climate connection abstract using data from the high resolution imaging science experiment hirise aboard the mars reconnaissance orbiter we reassess the methods by which layers within the north polar layered deposits npld can be delineated and their thicknesses measured apparent brightness and morphology alone are insufficient for this task high resolution topographic data are necessary from these analyses we find that the visible appearance of layers depends to a large degree on the distribution of younger mantling deposits which in turn is partially influenced by inherent layer properties and on the shape and location of the particular outcrop this younger mantle partially obscures layer morphology and brightness and is likely a cause of the gradational contacts between individual layers at this scale high resolution images reveal that there are several layers similar in appearance to the well known marker bed discovered by malin m edgett k 2001 j geophys res 106 23429 23570 the morphology thicknesses 4 8 2 m and separation distances 5 32 2 m of these marker beds as gleaned from a high resolution stereo digital elevation model lend insight into the connection between stratigraphy and climate

cyclostratigraphy and its revolutionizing applications in the earth and planetary sciences over the past 25 yr the science of stratigraphy has evolved to include time correlative data from vastly disparate components of the earth system not least of these is the global signal afforded by cyclostratigraphy which has recorded the evolution of earth s astronomical milankovitch forcing of insolation and the paleoclimate system fossil astronomical signals are collected from cyclic sedimentary sequences by detailed sampling and study of facies geochemistry mineralogy rock magnetism color etc in step with the documentation of astronomically forced paleoclimate from ever older older geologic times innovations in computational science have provided ever longer high accuracy astronomical model targets that can be used for time scale calibration the earth s orbit is affected by motions of other planets notably the orbital perihelia of venus and jupiter which impose a dominant 405 k y eccentricity cycle on earth s orbital evolution the large mass of jupiter stabilizes this cycle over hundreds of millions of years the cyclostratigraphic record of 405 k y cycles is therefore often used to correct chronologies affected by variable sedimentation earth s shape and rotation rate are influenced by tidal dissipation and climate friction these effects affect earth s precession rate through time thus a record of earth moon evolution is also embedded in cyclostratigraphy the geochronologic value of cyclostratigraphy has been affirmed through intercalibration with high precision radioisotope dating which today has the potential to define the ages of stratigraphic horizons with 2 uncertainties at the scale of a precession cycle precession index phasing relative to that of the obliquity elucidates the seasonal nature of astronomical forcing of the paleoclimate system cyclostratigraphy contributes to our knowledge of planetary dynamics for times prior to the current ca 50 ma limit of accurate astronomical solutions and it will guide our future understanding of solar system evolution and the evidence for chaotic diffusion astronomical modeling is undergoing its own revolution with development of new numerical integrators to extend accuracy further back in time finally space exploration has revealed prominent sedimentary bedding and ice stratigraphy on the surface of mars with patterns suggestive of astronomical forcing analogous to earth

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 spectral character of hawaiian basaltic glasses multispectral thermal infrared remote sensing of hawaiian basalts younger than a few hundred years old can be used to discriminate basalt lava flows that are difficult to map with visible and near infrared images laboratory thermal infrared reflectance spectra of the exposed surfaces of mauna loa and kilauea basalts show systematic changes with age fresh glass collected from active lava flows shows a broad reflectance feature between 8 and 12 m indicative of a strong degree of disorder after a few weeks of exposure to the environment the spectra of the top surfaces of samples begin to exhibit spectral features suggestive of ordering into silicate chainlike and sheetlike units with progressive aging features of apparent sheetlike structures become the preferred mode as soon as 3 years after emplacement a silica rich coating can begin to develop on the surfaces adding another spectral feature to the laboratory reflectance measurements the thermal infrared multispectral scanner tims with six channels between 8 and 12 m has been used to take advantage of these spectral differences in basalts to map flows in hawaii remote sensing instruments with increased spectral resolution in the thermal infrared would aid in further discrimination of basalts with more subtle differences in age quenching and weathering histories

planetary science communication arising volcanism or aqueous alteration on mars the mars global surveyor s thermal emission spectrometer has identified two global spectral surface types in martian dark regions which were initially interpreted as being of basaltic type 1 and intermediate type 2 basaltic andesite to andesite volcanic composition1 wyatt and mcsween2 suggest that northern hemisphere occurrences of the type 2 spectrum are instead representative of weathered basalt on the basis of ambiguity in the spectral interpretation and overlap between the distribution of this material and the outline of a putative ancient ocean although the spectral data may be open to interpretation within the limits of current understanding creating weathered basalt and explaining its distribution is problematic these competing hypotheses have significantly different implications for the igneous and aqueous history of mars and it is important to continue debating the merits of each

analysis of terrestrial and martian volcanic compositions using thermal emission spectroscopy 2 application to martian surface spectra from the mars global surveyor thermal emission spectrometer atmospherically corrected thermal infrared spectra of large regions of the martian surface from the mars global surveyor thermal emission spectrometer mgs tes previously have been interpreted to represent two general spectral classes one class represents a basalt to basaltic andesite composition and the other class represents a basaltic andesite to andesite composition we have performed new linear deconvolutions of the two martian surface type spectra with an end member set tailored to represent volcanic rock types our preparatory study of laboratory spectra of terrestrial volcanic rocks acquired at 2 cm 21 sampling convolved to tes spectral sampling 10 cm 21 shows little degradation in deconvolution results when compared to results acquired using the higher spectral resolution data indicating that the deconvolution technique is valid for analyzing data at tes resolution our spectral fits to the martian data agree well with previous models and do not exhibit any notable deviations from the martian spectra that would indicate the absence of any significant end members in our model modal mineralogies obtained with these new spectral fits also compare favorably within the previously stated uncertainties to prior results the newly derived modal mineralogies are used with new and traditional classification schemes for volcanic igneous rocks introduced in a companion paper wyatt et al this issue to classify the martian compositions our results substantiate the previously proposed hypothesis that these two spectral classes on the martian surface represent volcanic compositions with distinguishable differences in silica content ranging from basalt to andesite

spiral trough diversity on the north pole of mars as seen by shallow radar sharad we combine observations from ground penetrating radar and optical instruments to conduct a comprehensive survey of spiral troughs on the north polar layered deposits of mars our survey reveals that all north polar troughs have common characteristics but there is strong regional diversity we divide the north polar layered deposits npld into eight regions based on observations of morphology and stratigraphy in order to classify the spiral troughs morphologic features that separate the regions include central promontories topographic undulations bedrock floors and trough asymmetry among others we demonstrate here that the troughs formed during two periods the first generation of troughs formed on the main lobe and in part of gemina lingula during accumulation of 600 m of ice and dust the second generation of troughs formed stratigraphically higher and immediately after large scale erosion in gemini scopuli which we conclude created the slopes necessary for troughs to form we test scenarios of trough evolution and find that only three concurrent processes are required for their formation wind transport insolation induced sublimation and atmospheric deposition our observations are inconsistent with other hypothesized processes to produce spiral troughs including incision after the formation of the npld fracturing due to flowing ice and sublimation driven patterns from insolation

is there an orbital signal in the polar layered deposits on mars do the polar layered deposits on mars refl ect orbital control or stochastic variability it is fi useful to determine whether an orbital signal would be detected even if present an estimate of the uncertainty in the time depth relationship of the polar stratigraphy shows that nonlinearities in this relationship and noise in the signal will hamper or preclude detection of orbital forcing even if layer composition is directly proportional to insolation indeed stratigraphic sections of the north polar layered deposits reconstructed from spacecraft images yield no clear evidence of orbital control and are largely consistent with an autoregressive stochastic formation process there is however a broad rise in spectral power centered on a wavelength of roughly 1 6 m that appears in many of the stratigraphic sections this bedding may record a time scale associated with processes internal to mars climate system perhaps related to dust storms alternatively if formed in response to variations in mars obliquity or orbital precession the 1 6 m bedding implies that the 1 km thick upper north polar layered deposits formed over 30 70 myr

thermal infrared spectroscopy and modeling of experimentally shocked plagioclase feldspars thermal infrared emission and reflectance spectra 250 1400 cm 1 7 40 m of experimentally shocked albite and anorthite rich rocks 17 56 gpa demonstrate that plagioclase feldspars exhibit characteristic degradations in spectral features with increasing pressure new measurements of albite ab98 presented here display major spectral absorptions between 1000 1250 cm 1 8 10 m due to si o antisymmetric stretch motions of the silica tetrahedra and weaker absorptions between 350 700 cm 1 14 29 m due to si o si octahedral bending vibrations many of these features persist to higher pressures compared to similar features in measurements of shocked anorthite consistent with previous thermal infrared absorption studies of shocked feldspars a transparency feature at 855 cm 1 11 7 m observed in powdered albite spectra also degrades with increasing pressure similar to the 830 cm 1 12 0 m transparency feature in spectra of powders of shocked anorthite linear deconvolution models demonstrate that combinations of common mineral and glass spectra can replicate the spectra of shocked anorthite relatively well until shock pressures of 20 25 gpa above which model errors increase substantially coincident with the onset of diaplectic glass formation albite deconvolutions exhibit higher errors overall but do not change significantly with pressure likely because certain clay minerals selected by the model exhibit absorption features similar to those in highly shocked albite the implication for deconvolution of thermal infrared spectra of planetary surfaces or laboratory spectra of samples is that the use of highly shocked anorthite spectra in end member libraries could be helpful in identifying highly shocked calcic plagioclase feldspars

ultrahigh resolution topographic mapping of mars with mro hirise stereo images meter scale slopes of candidate phoenix landing sites 1 the objectives of this paper are twofold first to report our estimates of the meter to decameter scale topography and slopes of candidate landing sites for the phoenix mission based on analysis of mars global surveyor mgs mars orbiter camera moc images with a typical pixel scale of 3 m and mars reconnaissance orbiter mro high resolution imaging science experiment hirise images at 0 3 m pixel 1 and second to document in detail the geometric calibration software and procedures on which the photogrammetric analysis of hirise data is based a combination of optical design modeling laboratory observations star images and mars images form the basis for software in the u s geological survey integrated software for imagers and spectrometers isis 3 system that corrects the images for a variety of distortions with single pixel or subpixel accuracy corrected images are analyzed in the commercial photogrammetric software socet set bae systems yielding digital topographic models dtms with a grid spacing of 1 m 3 4 pixels that require minimal interactive editing photoclinometry yields dtms with single pixel grid spacing slopes from moc and hirise are comparable throughout the latitude zone of interest and compare favorably with those where past missions have landed successfully only the mars exploration rover mer b site in meridiani planum is smoother moc results at multiple locations have root mean square rms bidirectional slopes of 0 8 4 5 at baselines of 3 10 m hirise stereopairs one per final candidate site and one in the former site yield 1 8 2 8 slopes at 1 m baseline slopes at 1 m from photoclinometry are also in the range 2 3 after correction for image blur slopes exceeding the 16 phoenix safety limit are extremely rare

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

a test for the presence of covariance between time uncertain series of data with application to the dongge cave speleothem and atmospheric radiocarbon records 1 statistical measures of the relationships between time series are generally altered by the presence of errors in timing i e when applied to time uncertain series for example the covariance sampled between two time series which in truth covary will generally be decreased by errors in timing most previous work on this subject has sought to maximize some goodness of fit between time uncertain series either heuristically or through more quantitative methods however there is a danger that unrelated records can be made to appear to covary by time adjustment here we propose a statistical test for the presence of covariance between time uncertain series wherein the probability of obtaining a maximum covariance from randomly realized time uncertain series is assessed using the theory of order statistics the results of this analytical method provide insight into the influence of timing errors upon covariance and are shown to be consistent with results derived from a monte carlo procedure we apply this methodology to evaluate the covariance between a time uncertain stalagmite record and atmospheric radiocarbon during the holocene and find contradictory to previous interpretation that there is insignificant covariance between the two at the 95 confidence level

thermal infrared spectroscopy and modeling of experimentally shocked basalts new measurements of thermal infrared emission spectra 250 1400 cm 1 7 40 m of experimentally shocked basalt and basaltic andesite 17 56 gpa exhibit changes in spectral features with increasing pressure consistent with changes in the structure of plagioclase feldspars major spectral absorptions in unshocked rocks between 350 700 cm 1 due to si o si octahedral bending vibrations and between 1000 1250 cm 1 due to si o antisymmetric stretch motions of the silica tetrahedra transform at pressures 20 25 gpa to two broad spectral features centered near 950 1050 and 400 450 cm 1 linear deconvolution models using spectral libraries composed of common mineral and glass spectra replicate the spectra of shocked basalt relatively well up to shock pressures of 20 25 gpa above which model errors increase substantially coincident with the onset of diaplectic glass formation in plagioclase inclusion of shocked feldspar spectra in the libraries improves ts for more highly shocked basalt however deconvolution models of the basaltic andesite select shocked feldspar end members even for unshocked samples likely caused by the higher primary glass content in the basaltic andesite sample

subsurface structure of planum boreum from mars reconnaissance orbiter shallow radar soundings abstract we map the subsurface structure of planum boreum using sounding data from the shallow radar sharad instrument onboard the mars reconnaissance orbiter radar coverage throughout the 1 000 000 km2 area reveals widespread reflections from basal and internal interfaces of the north polar layered deposits npld a dome shaped zone of diffuse reflectivity up to 12 s 1 km thick underlies two thirds of the npld predominantly in the main lobe but also extending into the gemina lingula lobe across chasma boreale we equate this zone with a basal unit identified in image data as amazonian sand rich layered deposits byrne s murray b c 2002 j geophys res 107 5044 12 pp doi 10 1029 2001je001615 fishbaugh k e head j w 2005 icarus 174 444 474 tanaka k l rodriguez j a p skinner j a bourke m c fortezzo c m herkenhoff k e kolb e j okubo c h 2008 icarus 196 318 358 elsewhere the npld base is remarkably flat lying and co planar with the exposed surface of the surrounding vastitas borealis materials within the npld we delineate and map four units based on the radar layer packets of phillips et al phillips r j and 26 colleagues 2008 science 320 1182 1185 that extend throughout the deposits and a fifth unit confined to eastern gemina lingula we estimate the volume of each internal unit and of the entire npld stack 821 000 km3 exclusive of the basal unit correlation of these units to models of insolation cycles and polar deposition laskar j levrard b mustard j f 2002 nature 419 375 377 levrard b forget f montmessin f laskar j 2007 j geophys res 112 e06012 18 pp doi 10 1029 2006je002772 is consistent with the 4 2 ma age of the oldest preserved npld obtained by levrard et al levrard b forget f montmessin f laskar j 2007 j geophys res 112 e06012 18 pp doi 10 1029 2006je002772 we suggest a dominant layering mechanism of dust content variation during accumulation rather than one of lag production during periods of sublimation

analysis of terrestrial and martian volcanic compositions using thermal emission spectroscopy 1 determination of mineralogy chemistry and classification strategies we have examined and applied existing classification schemes for volcanic rocks and developed new schemes using thermal emission spectra of terrestrial volcanic rocks laboratory thermal infrared spectra 5 25 m at 2 cm 1 spectral sampling deconvolved modal mineralogies and derived mineral and bulk rock chemistries were used to distinguish basalt basaltic andesite andesite and dacite modal mineralogies derived from linear deconvolution of terrestrial volcanic rocks were compared to modes measured by an electron microprobe phase mapping technique to determine the accuracy of linear deconvolution in modeling specific mineral abundances one standard deviations of the absolute differences between modeled and measured mineral abundances range from 2 4 to 12 2 vol with an average standard deviation of 4 8 vol being in agreement with average uncertainties calculated in previous studies weighted average compositions of feldspars in the deconvolution generally overlap the measured ranges of plagioclase compositions and the presence of low calcium and high calcium pyroxenes was correctly identified bulk chemistries of volcanic rocks were derived with a relatively high degree of accuracy 1 standard deviations ranging from 0 4 to 2 6 vol by combining the compositions of spectrally modeled phases in proportion to their relative abundances in a particular sample these data were collectively used to examine existing and develop new volcanic rock classification schemes however no single classification scheme was effective in accurately classifying all samples multiple steps of classification were required to distinguish volcanic rocks reflecting the mineralogic diversity and continuum of compositions that exists in volcanic rock types in a companion paper hamilton et al this issue these schemes are applied to the classification of martian surface compositions

glacial anticyclone recorded in palouse loess of northwestern united states climate simulations for the last glacial maximum using general circulation models typically show a glacial anticyclone that produced an easterly wind anomaly south of the north american ice sheets evidence of this phenomenon has not been found in eolian sedimentary deposits that record surface wind patterns luminescence ages of loess and accompanying paleoecologic records from opal phytoliths and paleosol units across the columbia plateau washington state united states document a decrease up to fivefold in regional dust production and accumulation from 35 ka to 15 ka this interval corresponds to simulations indicating that a glacial anticyclone weakened prevailing south southwesterly winds that have shaped the eolian landscape of the columbia plateau since at least 75 ka at the same time that the glacial anticyclone suppressed dust production and accumulation enhanced cold and dry conditions resulted in soil formation dominated by intense bioturbation in periglacial steppe accompanied by shallow calcium carbonate precipitation this is the first evidence from eolian deposits in north america verifying that the glacial anticyclone altered surface wind patterns and affected eolian systems during the last glacial maximum

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

aeolian processes as drivers of landform evolution at the south pole of mars abstract we combine observations of surface morphology topography subsurface stratigraphy and near surface clouds with mesoscale simulations of south polar winds and temperature to investigate processes governing the evolution of spiral troughs on the south pole of mars in general we find that the south polar troughs are cyclic steps that all formed during an erosional period contrary to the troughs at the north pole which are constructional features the shallow radar instrument sharad onboard mars reconnaissance orbiter detects subsurface stratigraphy indicating relatively recent accumulation that occurred post trough formation in many locations using optical instruments especially the thermal emission imaging system themis we find low altitude trough clouds in over 500 images spanning 6 mars years the locations of detected clouds correspond to where recent accumulation is detected by sharad and offers clues about surface evolution the clouds migrate by season moving poleward from 71 s at l s 200 until l s 318 when the last cloud is detected our atmospheric simulations find that the fastest winds on the pole are found roughly near the external boundary of the seasonal co 2 ice cap thus we find that the migration of clouds and katabatic jumps corresponds spatially to the retreat of the co 2 seasonal ice as detected by titus 2005 and that trough morphology through recent accumulation is integrally related to this seasonal retreat

the high resolution imaging science experiment hirise during mro s primary science phase psp the high resolution imaging science experiment hirise on the mars reconnaissance orbiter mro acquired 8 terapixels of data in 9137 images of mars between october 2006 and december 2008 covering 0 55 of the surface images are typically 5 6 km wide with 3 color coverage over the central 20 of the swath and their scales usually range from 25 to 60 cm pixel nine hundred and sixty stereo pairs were acquired and more than 50 digital terrain models dtms completed these data have led to some of the most significant science results new methods to measure and correct distortions due to pointing jitter facilitate topographic and change detection studies at sub meter scales recent results address noachian bedrock stratigraphy fluvially deposited fans in craters and in or near valles marineris groundwater flow in fractures and porous media quasi periodic layering in polar and non polar deposits tectonic history of west candor chasma geometry of clay rich deposits near and within mawrth vallis dynamics of flood lavas in the cerberus palus region evidence for pyroclastic deposits columnar jointing in lava flows recent collapse pits evidence for water in well preserved impact craters newly discovered large rayed craters and glacial and periglacial processes of particular interest are ongoing processes such as those driven by the wind impact cratering avalanches of dust and or frost relatively bright deposits on steep gullied slopes and the dynamic seasonal processes over polar regions hirise has acquired hundreds of large images of past present and potential future landing sites and has contributed to scientific and engineering studies of those sites warming the focal plane electronics prior to imaging has mitigated an instrument anomaly that produces bad data under cold operating conditions