high resolution particle size analysis of naturally occurring very fine grained sediment through laser diffractometry abstract in this paper we present results from a large number of experiments aimed at quantifying method and instrument uncertainty associated with laser diffraction analysis we analyzed the size distribution of fine grained sediment 24 hours prior to analysis and using 60 seconds of ultrasonication during analysis 2 obscuration a measure of the concentration of the suspension during analysis produced the most reproducible results at about 20 3 variations in refractive index settings can significantly alter estimated grain size distributions 4 assumed values for absorption the degree to which sediment grains absorb the light can have a profound effect on grain size results absorption settings near 0 resulted in unexpected bimodal grain size distributions for sediments in the 10 m size fraction and significantly skewed the fine grained tail of coarser samples probably because of sub optimal diffraction by particles with a diameter similar in size to the laser wavelength absorption settings closer to 1 produced very reproducible results and unimodal grain size distributions over a wide range of refractive indexes our study has shown that laser diffraction can measure very fine grained sediments 10 m quickly with high precision 5 at 2 standard deviations and without the need for extensive mineralogical determinations these results make possible a new generation of studies in which high resolution time series data sets of sediment grain size can be used to infer subtle changes in paleohydrology

seeking phyllosilicates in thermal infrared data a laboratory and martian data case study 1 previous analyses of thermal emission spectrometer tes data produce results that could suggest a widespread distribution of phyllosilicate minerals over the surface of mars whereas studies of visible to near infrared vnir data indicate a more limited distribution we use vnir detections of phyllosilicates in the vicinity of the nili fossae to determine the spectral characteristics of phyllosilicate bearing material in the thermal infrared tir by investigating areas of vnir phyllosilicate detection in more detail we find that the phyllosilicate bearing material corresponds to spectral variation in thermal emission imaging system decorrelation stretched tir images and differences in infrared spectral shape that are consistent with but not uniquely attributable to mixtures of phyllosilicates and basalt phyllosilicate phases are modeled from tes data at abundances that average 5 over the region and at abundances near the 10 15 detection limit in our specific regions of interest deconvolution of numerical mixtures of phyllosilicate and basalt spectra indicates that these low abundances of phyllosilicates likely are not influenced by uncertainties greater than the 10 15 uncertainty of the method tes spectra and modeled abundances vary between the phyllosilicate bearing material and the surrounding region but this difference in composition cannot be attributed solely to the presence of phyllosilicates we believe the inconsistencies in phyllosilicate occurrence between tes and vnir analyses may be explained by the inclusion of phyllosilicates in the models of tes data as substitutes for poorly crystalline phases e g allophane not currently available in public infrared spectral libraries

composition morphology and stratigraphy of noachian crust around the isidis basin definitive exposures of pristine ancient crust on mars are rare and the finding that much of the ancient noachian terrain on mars exhibits evidence of phyllosilicate alteration adds further complexity we have analyzed high resolution data from the mars reconnaissance orbiter in the well exposed noachian crust surrounding the isidis basin we focus on data from the compact reconnaissance imaging spectrometer for mars as well as imaging data sets from high resolution imagine science experiment and context imager these data show the lowermost unit of noachian crust in this region is a complex brecciated unit of diverse compositions breccia blocks consisting of unaltered mafic rocks together with rocks showing signatures of fe mg phyllosilicates are commonly observed in regions of good exposure layered or banded phyllosilicate bearing breccia rocks are observed suggestive of pre isidis sedimentary deposits in places the phyllosilicate bearing material appears as a matrix surrounding mafic blocks and the mafic rocks show evidence of complex folded relationships possibly formed in the turbulent flow during emplacement of basin scale ejecta these materials likely include both pre isidis basement rocks as well as the brecciated products of the isidis basin forming event at 3 9 ga a banded olivine unit capped by a mafic unit covers a large topographic and geographic range from northwest of nili fossae to the southern edge of the isidis basin this olivine mafic cap combination superimposes the phyllosilicate bearing basement rocks and distinctly conforms to the underlying basement topography this may be due to draping of the topography by a fluid or tectonic deformation of a previously flatter lying morphology we interpret the draping superposed olivine mafic cap combination to be impact melt from the isidis basin forming event while some distinct post isidis alteration is evident carbonate kaolinite and serpentine the persistence of olivine from the time of isidis basin suggests that large scale aqueous alteration processes had ceased by the time this unit was emplaced

deep crustal carbonate rocks exposed by meteor impact on mars mars may have once had a co2 rich atmosphere but carbonate rocks that could provide evidence for such conditions are sparse spectral analyses of rocks exposed from deep within an impact crater reveal that carbonate deposits may be extensive on mars but are buried under layers of younger volcanic rocks

a new view of italian seismicity using 20 years of instrumental recordings in this paper we show the seismicity of the past 20 years that occurred in italy and surrounding regions hypocentral locations have been obtained by using p and s wave arrival times from the ingv national and several regional permanent seismic networks more than 48 000 events selected from an original data set of about 99 780 are used to reconstruct the most complete seismic picture of the italian region so far the seismicity distribution allows inference on seismotectonics of this complex region of subduction versus continental collision our results clearly reveal the geometry of the adria and the ionian subduction and a continuous normal fault belt in the upper crust following the apennines mountain range the depth of the seismogenic layer is computed from the cut off of seismicity at depth and shows large variations along and across the seismic active regions earthquakes are generated by the different velocity of slab retreat and the subsequent asthenospheric upwelling d 2004 elsevier b v all rights reserved

characteristics distribution origin and significance of opaline silica observed by the spirit rover in gusev crater mars 1 the presence of outcrops and soil regolith rich in opaline silica 65 92 wt sio2 in association with volcanic materials adjacent to the home plate feature in gusev crater is evidence for hydrothermal conditions the spirit rover has supplied a diverse set of observations that are used here to better understand the formation of silica and the activity abundance and fate of water in the first hydrothermal system to be explored in situ on mars we apply spectral chemical morphological textural and stratigraphic observations to assess whether the silica was produced by acid sulfate leaching of precursor rocks by precipitation from silica rich solutions or by some combination the apparent lack of s enrichment and the relatively low oxidation state of the home plate silica rich materials appear inconsistent with the originally proposed hawaiian analog for fumarolic acid sulfate leaching the stratiform distribution of the silica rich outcrops and their porous and brecciated microtextures are consistent with sinter produced by silica precipitation there is no evidence for crystalline quartz phases among the silica occurrences an indication of the lack of diagenetic maturation following the production of the amorphous opaline phase

earthquake locations and three dimensional crustal structure in the coyote lake area central california previous work on the simultaneous inversion method has been improved and extended to incorporate iterative solution for earthquake locations and laterally heterogeneous structure approximate ray tracing and parameter separation are important elements of the improved method application of the method to p wave arrival time data recorded by stations of the u s geological survey central california network yields a three dimensional model for the velocity structure of the upper crust in an area encompassing the rupture zone of the coyote lake earthquake of august 1979 very strong correlations between the velocity model and the geology and gravity and magnetic anomalies are observed improved estimates of the locations of earthquakes in the study area are also determined the relocation of explosions indicates epicentral accuracies of the order of a kilometer or better based on the revised hypocentral locations it is concluded that the san andreas fault is vertical in this area with no actual offset between the epicenters and the fault trace in contrast the calaveras has two or more active fault surfaces one nearly vertical and another dipping 75 to the northeast

distribution and characteristics of adirondack class basalt as observed by mini tes in gusev crater mars and its possible volcanic source abstract we identified 104 unique rock targets belonging to the olivine rich adirondack class using mini tes data rare rocks on the west spur of the columbia hills and on the plains east of the hills also belong to this class we present evidence that adirondack class basaltic lavas may have had their origin at apollinaris tholus linear modeling of adirondack class rock spectra shows only minor variations in mineralogy and the primary phases identified are consistent with olivine basalt having an average olivine composition of fo 45 we used factor analysis and target transformation to identify variability within a single class of rocks for the first time and we find that olivine abundance varies independently of a basaltic matrix a spectral component previously attributed to downwelling radiance is proposed here to be attributable to optically thin dust on rocks which has a greater effect on mini tes spectra than previously recognized but can explain the sloping continuum observed in adirondack class rock spectra as well as the apparent distortion of an olivine absorption spectral mixing is not completely linear leading to the overestimation of sulfate and olivine fractions and the underestimation of plagioclase feldspar although linear mixing appears to successfully replicate the majority of the observed signal published tes spectra of low albedo low dust cover olivine bearing materials do not exhibit the spectral telltales of non linear behavior probably because orbital spectra represent mostly mobile regolith that has not accumulated a sufficient dust cover over 3 6 km areas

basaltic andesite altered basalt and a tes based search for smectite clay minerals on mars 1 the global scale surface type 2 unit first identified with the mars global surveyor thermal emission spectrometer tes remains enigmatic competing hypotheses suggest that it represents either basaltic andesite or some form of altered basalt rich in dioctahedral smectite clay minerals and or spectrally similar amorphous silica phases common dioctahedral smectites contain a diagnostic feature in a portion of tes spectra that has been excluded in previous studies because of atmospheric co2 absorption we exploit the relative transparency of this spectral region to develop two indices that in tandem distinguish between certain smectites and amorphous phases smectites are not detected in northern lowlands type 2 settings consistent with other datasets but the case for primary or secondary amorphous silica phases is strengthened separately one index reveals an abundance of isolated type 2 occurrences in the southern high latitudes 50 associated with dunes the other shows olivine concentrations between 40 and 30

initial results from the mini tes experiment in gusev crater from the spirit rover the miniature thermal emission spectrometer mini tes on spirit has studied the mineralogy and thermophysical properties at gusev crater undisturbed soil spectra show evidence for minor carbonates and bound water rocks are olivinerich basalts with varying degrees of dust and other coatings dark toned soils observed on disturbed surfaces may be derived from rocks and have derived mineralogy 5 to 10 of 45 pyroxene 20 ca rich pyroxene and 25 pigeonite 40 sodic to intermediate plagioclase and 15 olivine forsterite 45 5 to 10 two spectrally distinct coatings are observed on rocks a possible indicator of the interaction of water rock and airfall dust diurnal temperature data indicate particle sizes from 40 to 80 microm in hollows to approximately 0 5 to 3 mm in soils

global distribution composition and abundance of olivine on the surface of mars from thermal infrared data 1 we used spectral indexing and linear deconvolution to compare thermal infrared emission spectra of fo91 fo68 fo53 fo39 fo18 and fo1 olivine samples to mars global surveyor thermal emission spectrometer tes data over low albedo regions of mars the fo91 fo68 fo53 and fo39 spectral end members were confidently identified on mars a range of compositions wider than inferred from martian meteorites small less than hundreds of square kilometers occurrences of the fo91 spectral end member are present in the rims of the argyre and hellas impact basins and may represent martian mantle materials the fo68 spectral end member is common throughout the highlands chasmata outflow channels and nili fossae region the fo53 spectral end member occurs in eastern syrtis major the nili fossae region and smooth floored craters of the highlands although less abundant than fo68 and fo53 the distribution of the fo39 spectral end member suggests that some olivine on mars is more fe rich than olivine in martian meteorites global maps of olivine show that 1 materials containing 10 20 of olivine are common in the southern highlands of mars 2 olivine is most common near the topographic dichotomy boundary and 3 olivine becomes uncommon near the poles suggesting that it may be influenced by topography and or latitude climate olivine is found in early noachian to amazonian terrains some of which may be coeval with phyllosilicate and sulfate deposits detected by omega implying that any early noachian wet period of mars climate history may have been globally inhomogeneous or insufficient to weather the olivine that remains today

morphology and composition of the surface of mars mars odyssey themis results the thermal emission imaging system themis on mars odyssey has produced infrared to visible wavelength images of the martian surface that show lithologically distinct layers with variable thickness implying temporal changes in the processes or environments during or after their formation kilometer scale exposures of bedrock are observed elsewhere airfall dust completely mantles the surface over thousands of square kilometers mars has compositional variations at 100 meter scales for example an exposure of olivine rich basalt in the walls of ganges chasma thermally distinct ejecta facies occur around some craters with variations associated with crater age polar observations have identified temporal patches of water frost in the north polar cap no thermal signatures associated with endogenic heat sources have been identified

applying the relative hypocentre location approach where was the 1980 november 23 irpinia earthquake the purpose of this work is to evaluate under what conditions it is feasible and with what accuracy it is possible to locate the nucleation point of a large earthquake given the availability of aftershocks located with high precision by the deployment of a local network we experiment with several approaches and apply them lo the location of the epicentre of the 1980 november 23 irpinia earthquake mw 6 9 first we use local pg phases selected to optimize the azimuthal coverage obtaining a well constrained location with a small statistical error which typically underestimates the true hypocentre uncertainty we then exploit the relative location technique obtaining stable almost coincident solutions under three conditions 1 using multiple independent master events to derive an average epicentre 2 fitting simultaneously the larger data set for all available master events using a forward approach 3 conducting an a priori evaluation of the statistics of station and master events to separate model uncertainties and improve the statistical accuracy of the relative locations moreover only by introducing station statistics can we achieve the desired accuracy of 1 km in constraining the rupture nucleation point of this large earthquake and we show that the application of the relative location technique to uncleaned unweighted data for a single master event provides only a crude epicentre with a confidence ellipse deceivingly smaller than the true hypocentre uncertainty the revised epicentre for the 1980 november 23 irpinia earthquake 48 803 n 15 302 e validates the class of multidisciplinary reconstructions of the source process such as the model of valensise et al 1989 based on the hypocentre of westaway jackson 1987 and is shifted by almost 13 km to the nw of the epicentre recently proposed by westaway 1992

mineralogy and stratigraphy of phyllosilicate bearing and dark mantling units in the greater mawrth vallis west arabia terra area constraints on geological origin 1 analyses of mro crism images of the greater mawrth vallis region of mars affirm the presence of two primary phyllosilicate assemblages throughout a region 1000 1000 km these two units consist of an fe mg phyllosilicate assemblage overlain by an al phyllosilicate and hydrated silica assemblage the lower unit contains fe mg smectites sometimes combined with one or more of these other fe mg phyllosilicates serpentine chlorite biotite and or vermiculite it is more than 100 m thick and finely layered at meter scales the upper unit includes al smectite kaolin group minerals and hydrated silica it is tens of meters thick and finely layered as well a common phyllosilicate stratigraphy and morphology is observed throughout the greater region wherever erosional windows are present this suggests that the geologic processes forming these units must have occurred on at least a regional scale sinuous ridges interpreted to be inverted channels and narrow channels cut into the upper clay bearing unit suggesting that aqueous processes were prevalent after and possibly during the deposition of the layered units we propose that layered units may have been deposited at mawrth vallis and then subsequently altered to form the hydrated units the fe mg phyllosilicate assemblage is consistent with hydrothermal alteration or pedogenesis of mafic to ultramafic rocks the al phyllosilicate hydrated silica unit may have formed through alteration of felsic material or via leaching of basaltic material through pedogenic alteration or a mildly acidic environment these phyllosilicate bearing units are overlain by a darker relatively unaltered and indurated material that has probably experienced a complex geological history

global mineral distributions on mars 1 determining the mineralogy of mars is an essential part of revealing the conditions of the surface and subsurface a deconvolution method was used to remove atmospheric components and determine surface mineralogy from thermal emission spectrometer data at 1 pixel per degree ppd minerals are grouped into categories on the basis of compositional and spectral similarity and global concentration maps are produced all binned pixels are fit well with rms errors of 0 005 in emissivity higher rms errors are attributed to short wavelength particle size effects on dust covered surfaces significant concentrations 0 10 of plagioclase high ca pyroxene sheet silicates high si glass and hematite are detected and display distributions consistent with previous studies elevated concentrations of plagioclase and high ca pyroxene are consistent with basaltic surfaces and are located in low albedo highlands regions north of 45 s significant concentrations of plagioclase and sheet silicates high si glass and low concentrations of high ca pyroxenes are consistent with andesitic surfaces and are concentrated in both southern and northern high latitude low albedo regions andesitic surfaces in the southern hemisphere have a lower spectral contrast than northern surfaces an isolated surface located in solis planum is spectrally distinct but compositionally similar to other surfaces interpreted to be andesitic in composition concentrations of olivine below the detection limit correctly identify its presence in two of three locations potassium feldspar low ca pyroxene basaltic glass olivine sulfate carbonate quartz and amphibole are not detected with confidence at 1 ppd the results presented here indicate a predominance of volcanic compositions within martian dust free surfaces

crustal structure in the area of the 2002 molise earthquake clues for the evolution of the southern apennines the apennines is a mountain belt with paired extension and compression that are explained by the subduction and delamination of the ionian adria lithosphere during the belt formation the adria crust is flexed downward and then incorporated into the wedge after peeling off along some weak level whose origin is still discussed in southern apennines this process seems to have stopped at about 0 7 ma by the development of a tear in the subducting lithosphere and consequent extension that spread along the mountain range seismological data acquired after the 2002 mw 6 0 molise strike slip earthquake yield modeling the structure of the adria crust as congealed close to the leading edge of the belt tomography images show inverted normal faults within the sedimentary cover apulian units fault inversion incomplete close to the compressional front testifies for a final squeezing of the entire previously flexed apulian continental margin pronounced high vp and low vp vs anomalies are observed at depth greater than 12 km and undoubtfully attributed to heterogeneities of the basement solving the long lasting contention on the nature of similar high speed bodies observed beneath the apennines beneath these bodies we observe a strong reflectivity suggesting the presence of a fluid filled layer in the middle lower crust that may act as a decoupling level in the apennines tectonics the deep fluids are also favoring the rupture of strike slip earthquakes like those that occurred in 2002 and the intermediate depth seismicity diffused in the apulian region

dinosaur egg bearing deposits upper cretaceous of boseong korea occurrence palaeoenvironments taphonomy and preservation abstract dinosaur sauropod and ornithopod egg bearing deposits of the upper cretaceous seonso conglomerate boseong korea were examined sedimentologically for palaeoenvironmental and preservational interpretation dinosaur eggs are commonly preserved as clutches although isolated eggs also occur the clutches are found in at least six horizons consisting of sandy mudstones to mudstones these strata are interpreted as terminal fan deposits calcite rims and calcite aureols around detrital grains pedotubular to nodular calcretes and circumgranular to circumnodular cracks are present in the dinosaur egg deposits these features indicate calcareous pedogenesis which appears to have assisted in the preservation of the eggs in one egg deposit in which clutches are mostly found vertic features including pedogenic slickensides pseudoanticlines and calcite filled deep desiccation cracks occur the preservation of these dinosaur eggs in calcic and vertic palaeosols suggests that the palaeoclimate of the nested area was semiarid the lack of displacement of eggs and egg shells the presence of some egg clutches 5 10 cm below flood deposits and the porous nature of the eggshells suggest that the eggs were laid in excavated nests that were buried during incubation the preservation of numerous dinosaur clutches in several horizons at boseong is consistent with site fidelity

playa lake and sheetflood deposits of the upper cretaceous jindong formation korea occurrences and palaeoenvironments abstract lake model of the upper cretaceous jindong formation in korea was established on the basis of sedimentological and palaeobiological records of the playa lake and sheetflood deposits and their palaeoenvironmental implications the playa lake and sheetflood deposits of the jindong formation are characterized by the common presence of traces of vanished evaporites complicated polygonal desiccation cracks and rainprints the pedogenic carbonate development and the preservation of invertebrate traces and dinosaur and bird tracks the traces of vanished evaporites including halite and sulphate evaporite occur as evaporite pseudopmorphs and moulds the occurrence of all of the evaporite minerals as traces suggests that flooding stages persisted much longer than evaporation and desiccation stages invertebrates birds and dinosaurs inhabited the playa lake environment of the upper cretaceous jindong lake the jindong lake formed by the combination of humid source area and arid depositional site due to an orographic effect in fault bounded basin extensive development of the playa lake and sheetflood deposits with evaporite mineral casts and very limited association of shoreline deposits in the jindong formation are characteristic of closed lake and the jindong lake is compared to a lake formed in partly drained closed basin the aggradation of mudflat deposits indicates continued subsidence of the basin and continuation of an underfilled lake basin the jindong lake expanded and stabilized as a playa lake surrounded by dry to saline mudflats and palaeoclimate and subsidence rates changed little throughout the period of the jindong lake development

quantitative compositional analysis of sedimentary materials using thermal emission spectroscopy 1 application to sedimentary rocks thermal emission spectroscopy is used to determine the mineralogy of sandstone and mudstone rocks as part of an investigation of linear spectral mixing between sedimentary constituent phases with widespread occurrences of sedimentary rocks on the surface of mars critical examination of the accuracy associated with quantitative models of mineral abundances derived from thermal emission spectra of sedimentary materials is necessary although thermal emission spectroscopy has been previously proven to be a viable technique to obtain quantitative mineralogy from igneous and metamorphic materials sedimentary rocks with natural variation of composition compaction and grain size have yet to be examined in this work we present an analysis of the thermal emission spectral 270 1650 cm 1 characteristics of a suite of 13 sandstones and 14 mudstones x ray diffraction and traditional point counting procedures were all evaluated in comparison with thermal emission spectroscopy results from this work are consistent with previous thermal emission spectroscopy studies and indicate that bulk rock mineral abundances can be estimated within 11 2 for detrital grains i e quartz and feldspars and 14 8 for all other mineral phases present in both sandstones and mudstones in comparison to common in situ techniques used for determining bulk rock composition clay sized to fine silt sized grained phase identification is less accurate with differences from the known ranging from 5 to 24 on average nevertheless linear least squares modeling of thermal emission spectra is an advantageous technique for determining abundances of detrital grains and sedimentary matrix and for providing a rapid classification of clastic rocks

surface and crater exposed lithologic units of the isidis basin as mapped by coanalysis of themis and tes derived data products 1 the stratigraphy and mineral heterogeneity of surface and crater exposed deposits in the southwestern portion of the isidis basin were investigated using spatial spectral visible and thermophysical data sets from both the mars global surveyor and odyssey missions four themis spectral surface units were identified progressing from the libya montes highlands to the inner lowland plains of isidis planitia lithologic determinations of these spectral units were made by linear deconvolution analysis of tes data olivine rich surface materials correlate with a well documented high thermal inertia unit based on spatial and stratigraphic relationships interpreted from both crater exposed and surface exposures the olivine rich unit was determined to have formed subsequent to the isidis basin forming event morphology occurrence and linear deconvolution of this unit suggests that it may represent noachian age to hesperian age picritic lavas that erupted as early stage lavas originating from sources such as syrtis major beneath isidis and as far as tyrrhena patera these lavas are suggested to have partially filled the basin based on crater exposed occurrences and were subsequently buried by further evolved olivine poor lavas later these lavas were exposed by erosion and subsequent impacts into the basin crater scaling suggests significant infilling of the basin by these lavas that may account for craters with very high d d ratios and the well developed positive mass anomaly associated with the basin this study also demonstrates that the remote sensing of impact craters in conjunction with surface mapping is a potent mapping tool for understanding stratigraphy and the petrogenesis of the martian crust

observations of the relationship between ionospheric central polar cap and dayside throat convection velocities and solar wind imf driving convection observations from the southern hemisphere super dual auroral radar network are presented and examined for their relationship to solar wind and interplanetary magnetic field imf conditions restricted to periods of steady imf analysis is concentrated on two specific regions the central polar cap and the dayside throat region an example time series is discussed in detail with specific examples of apparent direct control of the convection velocity by the solar wind driver closer examination however shows that there is variability in the flows that cannot be explained by the driving scatterplots and histograms of observations from all periods in the year 2013 that met the selection criteria are given and their dependence on solar wind driving is examined it is found that on average the flow velocity depends on the square root of the rate of flux entry to the polar cap it is also found that there is a large level of variability that is not strongly related to the solar wind driving

using themis data to resolve the discrepancy between crism omega and tes modeled phyllosilicate abundance in mawrth vallis abstract we explore the effects of spatial resolution on the detectability of phyllosilicates in the thermal infrared dataset from the mars global surveyor thermal emission spectrometer tes data from the mars odyssey thermal emission imaging system themis instrument is used to resolve spatial resolution driven discrepancies between detection of phyllosilicates in the infrared and visible near infrared wavelength range the 100 m pixel spatial resolution offered by themis even with its limited spectral resolution significantly improves the likelihood of phyllosilicate detection furthermore spectral unit mapping techniques provide the first phyllosilicate abundance maps of the mawrth vallis phyllosilicate bearing units which indicate phyllosilicate abundances of 50 with heterogeneous spatial distributions derived abundances are used to evaluate the proposed formation mechanisms for phyllosilicates in this region and are found to be consistent with intermediate weathering of mafic primary material

hydrated mineral stratigraphy of ius chasma valles marineris new high resolution spectral and morphologic imaging of deposits on walls and floor of ius chasma extend previous geomorphic mapping and permit a new interpretation of aqueous processes that occurred during the development of valles marineris we identify hydrated mineralogy based on visible near infrared vnir absorptions we map the extents of these units with crism spectral data as well as morphologies in ctx and hirise imagery three cross sections across ius chasma illustrate the interpreted mineral stratigraphy multiple episodes formed and transported hydrated minerals within ius chasma polyhydrated sulfate and kieserite are found within a closed basin at the lowest elevations in the chasma they may have been precipitates in a closed basin or diagenetically altered after deposition fluvial or aeolian processes then deposited layered fe mg smectite and hydrated silicate on the chasma floor postdating the sulfates the smectite apparently was weathered out of noachian age wallrock and transported to the depositional sites the overlying hydrated silicate is interpreted to be an acid leached phyllosilicate transformed from the underlying smectite unit or a smectite jarosite mixture the finely layered smectite and massive hydrated silicate units have an erosional unconformity between them that marks a change in surface water chemistry landslides transported large blocks of wallrock some altered to contain fe mg smectite to the chasma floor after the last episode of normal faulting and subsequent landslides opal was transported short distances into the chasma from a few m thick light toned layer near the top of the wallrock by sapping channels in louros valles alternatively the material was transported into the chasma and then altered to opal the superposition of different types of hydrated minerals and the different fluvial morphologies of the units containing them indicate sequential distinct aqueous environments characterized by alkaline then circum neutral and finally very acidic surface or groundwater chemistry

mars remote sensing analog studies in the badwater basin death valley california 1 the search for evaporites on mars has important implications for the role that liquid water has played in shaping the planet s geologic climatic and potential biologic history orbital investigations of surface mineralogy are crucial to this exploration effort with the exception of coarse grained gray hematite at a restricted number of sites and trace amounts of carbonate in globally distributed dust deposits the thermal emission spectrometer tes and thermal emission imaging system themis instruments have yet to find widespread mineralogical evidence of aqueously formed minerals this may reflect the coarse spatial resolution of tes 3 5 km pixel and low spectral resolution of themis 10 bands between 6 5 and 14 5 m spectral mapping in the badwater basin death valley california was conducted to better understand the capabilities of tes and themis in detecting evaporite minerals high resolution modis aster airborne simulator master data degraded to tes and themis spatial resolutions were used to evaluate the detection limits of sulfates and carbonates to assess the validity of this spectral remote sensing a quantitative ground truth analysis of surface mineralogy in the badwater basin was performed the analysis was based on thin section petrography x ray diffraction electron microprobe and laboratory and field thermal emission spectrometer analyses taken together the results of all five methods provided enough constraints for a robust interpretation that was in general agreement with the spectral remote sensing mapping study for 90 of the surface samples examined

traces of evaporites in upper cretaceous lacustrine deposits of korea origin and paleoenvironmental implications abstract diverse types of halite and sulfate evaporite traces occur in the upper cretaceous lacustrine deposits of the jindong formation and the jangdong tuff in korea in which dinosaur tracks are common the halite traces usually occur as casts or moulds and they include traces of primary halite hoppers primary and intrasedimentary skeletal halite and intrasedimentary tiny halite the sulfate traces occur as intrasedimentary and displacive casts filled with sediments and sparry calcite and the casts occur as diverse modes from single crystal casts through nodular aggregates to massive aggregates some aggregates of the sulfate casts are aligned in crack pattern and selective occurrence of the laths in ripple troughs are observed soluble sulfate evaporite minerals such as gypsum glauberite or mirabilite are probable for the precursors of these traces these halite and sulfate traces are interpreted to have been formed in a saline lake and mudflats it is interpreted that meteoric water was responsible for the evaporite precipitation in the jindong lake and jangdong lake recycled brine produced by the repeated dissolution of evaporites might contribute to the evaporite precipitation in the paleo jindong lake and the paleo jangdong lake the development of saline lake deposits in the jindong formation and the jangdong tuff suggests that the southern part of the korean peninsula remained an inland continental area during the cretaceous resulting in semi arid paleoclimatic condition due to an orographic effect by the location of the korean peninsula on continental margin in mid latitude with topographic barriers during the cretaceous the occurrence of dinosaur tracks in the lake margin deposits of saline lake with frequent inflow of dilute meteoric water suggests that upper cretaceous dinosaurs inhabiting lakes on the korean peninsula might have drunken brackish water

aftershocks of the campania lucania italy earthquake of 23 november 1980 abstract the result of a study of 1130 aftershocks of the 1980 campania lucania earthquake are presented the data were collected primarily with a dense array of portable smoked drum seismographs deployed in the epicentral region a few days after the main shock tests performed on subsets of the data to establish the location accuracy are described in detail and epicentral maps and cross sections are presented and discussed one hundred and sixty well constrained fault plane solutions using upward traveling rays are presented the distribution of aftershocks forms an elongate cloud which does not define a plane this is not because the events are poorly located a subset of events located with epicentral errors of less than 1 km and depth errors less than 2 km forms a similar cloud to the complete aftershock set the aftershock mechanisms are very varied some are similar to the main event but many differ profoundly these include events on shallow or vertical planes and thrust events the latter include some events which require contraction in the direction in which the main event indicates extension the aftershocks of all mechanisms are intermixed in space in such a way that no simple system of faults can explain them a model to explain the aftershocks and the lack of surface ruptures in the main event is offered it is proposed that the main shock cuts between two aseismic detachment surfaces and that the aftershocks are a consequence of the complicated deformation that such a geometry demands whatever interpretation is adopted the results are a challenge to the commonly accepted view that aftershocks even approximately define simple fault planes or that aftershock mechanisms replicate the mechanism of the main shock defects in interpretations of the main shock and aftershocks process arise largely from a lack of information about the geometry of structures at depth in the epicentral region suitable deep reflection profiles could help to resolve this problem

mineralogy of the light toned outcrop at meridiani planum as seen by the miniature thermal emission spectrometer and implications for its formation 1 analysis of miniature thermal emission spectrometer mini tes data has led to the recovery of a pure end member spectral shape related to the light toned outcrop observed at meridiani planum data from the mer mossbauer spectrometer apxs and previous mini tes measurements were used to constrain a spectral library used to determine the mineralogy of the outcrop from this spectral shape linear deconvolution of the outcrop spectral shape suggests that it is composed primarily of al rich opaline silica mg ca and fe bearing sulfates plagioclase feldspar nontronite and hematite conversion of modeled mineralogy to chemistry shows good agreement with the chemical composition of the outcrops determined by apxs details of the analysis procedure and implications for the formation of the outcrop are discussed along with terrestrial analogs of the ancient environment at meridiani

clay minerals in delta deposits and organic preservation potential on mars clay rich sedimentary deposits are often sites of organic matter preservation and have therefore been sought in mars exploration however regional deposits of hydrous minerals including phyllosilicates and sulphates are not typically associated with valley networks and layered sediments that provide geomorphic evidence of surface water transport on early mars the compact reconnaissance imaging spectrometer for mars crism has recently identified phyllosilicates within three lake basins with fans or deltas that indicate sustained sediment deposition eberswalde crater holden crater and jezero crater here we use high resolution data from the mars reconnaissance orbiter mro to identify clay rich fluvial lacustrine sediments within jezero crater which has a diameter of 45 km the crater is an open lake basin on mars with sedimentary deposits of hydrous minerals sourced from a smectite rich catchment in the nili fossae region we find that the two deltas and the lowest observed stratigraphic layer within the crater host iron magnesium smectite clay jezero crater holds sediments that record multiple episodes of aqueous activity on early mars we suggest that this depositional setting and the smectite mineralogy make these deltaic deposits well suited for the sequestration and preservation of organic material

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

a habitable fluvio lacustrine environment at yellowknife bay gale crater mars the curiosity rover discovered fine grained sedimentary rocks which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy this aqueous environment was characterized by neutral ph low salinity and variable redox states of both iron and sulfur species carbon hydrogen oxygen sulfur nitrogen and phosphorus were measured directly as key biogenic elements by inference phosphorus is assumed to have been available the environment probably had a minimum duration of hundreds to tens of thousands of years these results highlight the biological viability of fluvial lacustrine environments in the post noachian history of mars

three dimensional earthquake locations and upper crustal structure of the sannio matese region southern italy abstract the sannio matese region is one of the most seismically active regions of italy and has been struck by large historical earthquakes at present the area is characterized by low magnitude background seismicity and small seismic sequences following m 4 main events in this paper we show vp and vp vs models and 3d locations for a complete set of earthquakes occurring in the period 1991 2001 we observe a significant crustal heterogeneity with large scale east verging high vp fault related folds stacked by the pliocene compression the relocated earthquakes cluster along a 70 east dipping nw striking plane located at the border of the high vp thrust units normal fault earthquakes related to the young and active extension occur within these high vp zones interpreted as high strength material we expect large future earthquakes to occur within these high vp zones actually characterized by low magnitude seismicity at their borders

thermal infrared spectroscopy and partial least squares regression to determine mineral modes of granitoid rocks 1 in this paper we present an approach to extracting mineralogic information from thermal infrared tir spectra that is not based on an input library of pure mineral spectra nor tries to extract spectral end members from the data instead existing modal mineralogy for a number of samples are used to build a partial least squares regression plsr model that links the mineralogy of the samples to their respective tir spectral signatures the resulting plsr models can be applied to a larger group of samples for which the mineralogic composition can be estimated from the tir spectra alone thermal infrared reflectance spectra were recorded from 1330 625 cm 1 7 5 to 16 0 m the method is tested on igneous rocks from a porphyry copper deposit in yerington nevada as a reference modal mineralogic composition was determined with traditional polarization microscopy on thin sections partial least squares regression models were developed to link the thermal infrared spectra to the thin section determined mineral modes of alkali feldspar plagioclase and quartz as well as the average plagioclase composition information results indicate that rock samples can be classified successfully in a quartz alkali feldspar plagioclase diagram based on thermal infrared spectroscopy and partial least squares regression modeling estimated errors for the mineralogic composition model results were found to be smaller or equal to traditional methods with errors of 5 1 absolute for alkali feldspar 8 5 absolute for plagioclase and 6 9 absolute for quartz the regression model for plagioclase composition predicted with estimated errors of 7 8 mol anorthite

depositional depth of laminated carbonate deposits insights from the lower cretaceous valdeprado formation cameros basin northern spain the lower cretaceous berriasian valdeprado formation cameros basin northern spain contains more than 900 m of laminated carbonates and pseudomorphs after sulfates traditionally many sedimentary packages of different ages and lithologies have been interpreted as deep water deposits based essentially on the abundance of laminations and the absence of subaerial exposure features in contrast the valdeprado formation provides an example of a shallow water deposit dominated by laminations with scarce evidence of subaerial exposure and gives criteria to solve the challenge of distinguishing shallow water and deep water ancient laminated deposits the two most abundant facies all along the valdeprado formation are a parallel laminated limestone formed by alternating carbonate mudstone and calcite and quartz pseudomorphs after displacive gypsum and b graded laminated limestone consisting of quartz mica ostracodes and pseudomorphs after detrital gypsum grains at the base which changes gradually upwards to carbonate mudstone parallel laminated limestone and graded laminated limestone could have been deposited in either deep or shallow environments as a result of salinity fluctuations driven by alternation of flooding and evaporation and by sediment resuspension processes respectively subaerial exposure features such as desiccation mudcracks are scarce in most of the succession except in a few meter scale stratigraphic intervals where they are very abundant interestingly in these intervals desiccation cracks are present at the tops of several successive laminae up to 25 mudcracked laminae per meter of deposit indicating that at least during those periods of time deposition occurred in shallow water bodies that were desiccated frequently in the upper part of the stratigraphic section parallel laminated and graded laminated limestones are associated with current ripple and wave ripple cross laminated arenites and ostracode mudstone to wackestone with centimeter size pseudomorphs after lenticular gypsum and abundant desiccation mudcracks and tepees which also suggest sedimentation in shallow water environments moreover the laminated carbonates display continuous parallel layering and the same facies along the 40 km long outcropping area these deposits are directly interbedded with and pass laterally to siliciclastic sandy muddy flat deposits in the western area of the basin without clinoforms slump structures or slide masses in between all of these features suggest deposition in shallow perennial carbonate sulfate water bodies and their peripheral mudflats developed in a flat bottomed basin with no marked gradients

the rocks of gusev crater as viewed by the mini tes instrument 1 the miniature thermal emission spectrometer mini tes on board the mars exploration rover spirit is part of a payload designed to investigate whether a lake once existed in gusev crater mini tes has observed hundreds of rocks along the rover s traverse into the columbia hills yielding information on their distribution bulk mineralogy and the potential role of water at the site although dust in various forms produces contributions to the spectra we have established techniques for dealing with it all of the rocks encountered on the plains traverse from the lander to the base of the columbia hills share common spectral features consistent with an olivine rich basaltic rock known as adirondack class beginning at the base of the west spur of the columbia hills and across its length the rocks are spectrally distinct from the plains but can be grouped into a common type called clovis class these rocks some of which appear as in place outcrop are dominated by a component whose spectral character is consistent with unaltered basaltic glass despite evidence from other rover instruments for significant alteration the northwest flank of husband hill is covered in float rocks known as wishstone class with spectral features that can be attributed uniquely to plagioclase feldspar a phase that represents more than half of the bulk mineralogy rare exceptions are three classes of basaltic exotics found scattered across husband hill that may represent impact ejecta and or float derived from local intrusions within the hills the rare outcrops observed on husband hill display distinctive spectral characteristics the outcrop called peace shows a feature attributable to molecular bound water and the outcrop that hosts the rock called watchtower displays a dominant basaltic glass component despite evidence from the rover s payload for significant alteration of some of the rocks no unambiguous detection of crystalline phyllosilicates or other secondary silicates has been observed by mini tes the mineralogical results supplied by mini tes provide no clear evidence that a lake once existed in gusev crater

structural control on fault geometry example of the grevena ms 6 6 normal faulting earthquake in this paper we present a three dimensional velocity structure of the kozani grevena region a relatively low seismicity area of the western margin of the internal hellenides which was struck by a ms 6 6 earthquake on may 13 1995 p wave arrival times from 656 aftershocks are inverted to resolve the velocity structure of the upper 12 km of the crust the 1995 ruptured fault dheskati fault lies at the southeastern end of a 35 km long normal fault the servia fault the crustal heterogeneities identified by tomography help to constrain the geometry and structure of the 1995 fault and the rupture evolution during the mainshock the aftershocks and the velocity structure define a fault dipping 35 toward nw which from 5 km depth splays upward into two nearly parallel shallow faults the slip during the mainshock and the aftershocks all were concentrated along the deeper portion of the fault while the limited slip observed at the surface occurred on the northern of the two shallower splays the paleochori fault it appears that the lithological heterogeneities of the shallow crust are responsible for the splaying of the main fault upward our work stresses the importance of crustal structure in determining fault geometry and segmentation and rupture evolution

paleoclimate of mars as captured by the stratigraphic record in gale crater a kilometers thick sedimentary sequence in gale crater exhibits stratigraphic changes in lithology that are consistent with transitions in aqueous and climatic conditions purported to be global in scale the sequence is divided into two formations where the lower formation exhibits a net transition in mineralogy from clay sulfate to sulfate oxide assemblages and is separated from the overlying upper formation by an erosional unconformity superposition and crater counts suggest strata in the lower formation lie along the noachian hesperian time stratigraphic boundary whereas beds in the upper formation which lack signatures indicative of clay minerals or sulfates are thinner more regularly spaced and clearly younger the observed stratigraphic trends are consistent with the rocks at gale crater recording a global transition from a climate favorable to clay mineral formation to one more favorable to forming sulfates and other salts

in situ evidence for an ancient aqueous environment at meridiani planum mars sedimentary rocks at eagle crater in meridiani planum are composed of fine grained siliciclastic materials derived from weathering of basaltic rocks sulfate minerals including magnesium sulfate and jarosite that constitute several tens of percent of the rock by weight and hematite cross stratification observed in rock outcrops indicates eolian and aqueous transport diagenetic features include hematite rich concretions and crystal mold vugs we interpret the rocks to be a mixture of chemical and siliciclastic sediments with a complex diagenetic history the environmental conditions that they record include episodic inundation by shallow surface water evaporation and desiccation the geologic record at meridiani planum suggests that conditions were suitable for biological activity for a period of time in martian history

the rupture process of the 1980 irpinia italy earthquake from the inversion of strong motion waveforms abstract the distribution of slip and the behaviour of rupture propagation during the 23rd november 1980 irpinia earthquake ms 6 9 was investigated by analysing strong motion accelerograms the rupture was assumed to develop on a two dimensional purely normal fault whose geometry was constrained by geologic and geodetic data and by the aftershock space distribution theoretical seismograms have been computed using the isochron approach with a spatially variable slip intensity the asymptotic ray theory is used to evaluate the far field green functions the rupture model was updated following a trial and error approach the fit of observed waveforms with synthetic seismograms allowed several peculiarities in the rupture history to be pointed out the source model resulting from the solution of the forward waveform modelling was then used as starting model for the inversion of ground velocities therefore we performed a linearized inversion for slip velocity and rupture times on the fault by iteratively perturbing the assumed starting model the inverse problem is solved by means of a tomographic back projection technique the inferred source model shows a bilateral rupture which does not propagate uniformly away from the hypocentre the rupture velocity and the slip distribution on the fault plane are rather variable the solution confirms the shallow dislocation gap in the central part of the fault suggested by the behaviour of the surface rupture the results indicate that the rupture propagated northwestward along a further fault fragment for which no surface evidence is observed the aftershocks occurred mostly inside of or near to the edges of the source areas of maximum co seismic slip

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

the irpinia italy 1980 earthquake detailed analysis of a complex normal faulting a detailed analysis of near source strong motion and leveling data together with the results of teleseismic waveform modeling by westaway and jackson 1987 and aftershock studies by deschamps and king 1984 allows a satisfactory kinematic description of the complex normal faulting associated with the magnitude ms 6 9 november 23 1980 irpinia earthquake southern italy the three main rupture episodes starting at about 0 20 and 40 s are here associated with better constrained source parameters than in previous studies we first evaluated the triggering time for the 11 closest accelerometers by using the well recorded 40 s strong motion phases this gave the absolute time and location of the dominant episodes of faulting the first rupture propagated mainly toward the northwest on a ne dipping normal fault at a mean velocity close to 3 km s for about 20 km and continued 15 km further on smaller subfaults it was associated with surface breakage in the southeastern part the second rupture started from the southeastern end of the first rupture about 18 s after it and propagated about 20 km toward the southeast on a low angle normal fault dipping 20 ne it was associated with secondary faulting on steeper planes reaching the surface the third and last episode at 39 s nucleated near the first hypocenter at shallower depth and the rupture possibly propagated on a 10 to 15 km long normal fault striking se antithetic to the first activated fault a clear correlation appears between the strength of the geological formations and the existence of surface breakage and shallow aftershock activity

quantitative compositional analysis of sedimentary materials using thermal emission spectroscopy 2 application to compacted fine grained mineral mixtures and assessment of applicability of partial least squares methods fine grained sedimentary deposits on planetary surfaces require quantitative assessment of mineral abundances in order to better understand the environments in which they formed one way that planetary surface mineralogy is commonly assessed is through thermal emission 6 50 m spectroscopy to that end we characterized the tir spectral properties of compacted very fine grained mineral mixtures of oligoclase augite calcite montmorillonite and gypsum non negative linear least squares minimization nnls is used to assess the linearity of spectral combination a partial least squares pls method is also applied to emission spectra of fine grained synthetic mixtures and natural mudstones to assess its applicability to fine grained rocks the nnls modeled abundances for all five minerals investigated are within 10 of the known abundances for 39 of the mixtures showing the relationships between known and modeled abundance follow non linear curves the poor performance of nnls is due to photon transmission through small grains over portions of the wavelength range and multiple reflections in the volume the pls method was able to accurately recover the known abundances to within 10 for 78 90 of synthetic mixtures and for 85 of the mudstone samples chosen for this study the excellent agreement between known and modeled abundances is likely due to high absorption coefficients over portions of the thermal infrared tir spectral range and thus combinations are linear over portions of the range pls can be used to recover abundances from very fine grained rocks from tir measurements and could potentially be applied to landed or orbital tir observations

orbital identification of carbonate bearing rocks on mars geochemical models for mars predict carbonate formation during aqueous alteration carbonate bearing rocks had not previously been detected on mars surface but mars reconnaissance orbiter mapping reveals a regional rock layer with near infrared spectral characteristics that are consistent with the presence of magnesium carbonate in the nili fossae region the carbonate is closely associated with both phyllosilicate bearing and olivine rich rock units and probably formed during the noachian or early hesperian era from the alteration of olivine by either hydrothermal fluids or near surface water the presence of carbonate as well as accompanying clays suggests that waters were neutral to alkaline at the time of its formation and that acidic weathering proposed to be characteristic of hesperian mars did not destroy these carbonates and thus did not dominate all aqueous environments

mapping variations in weight percent silica measured from multispectral thermal infrared imagery examples from the hiller mountains nevada usa and tres virgenes la reforma baja california sur mexico remotely sensed multispectral thermal infrared 8 13 m images are increasingly being used to map variations in surface silicate mineralogy these studies utilize the shift to longer wavelengths in the main spectral feature in minerals in this wavelength region reststrahlen band as the mineralogy changes from felsic to mafic an approach is described for determining the amount of this shift and then using the shift with a reference curve derived from laboratory data to remotely determine the weight percent sio 2 of the surface the approach has broad applicability to many study areas and can also be fine tuned to give greater accuracy in a particular study area if field samples are available the approach was assessed using airborne multispectral thermal infrared images from the hiller mountains nevada usa and the tres virgenes la reforma baja california sur mexico results indicate the general approach slightly overestimates the weight percent sio 2 of low silica rocks e g basalt and underestimates the weight percent sio 2 of high silica rocks e g granite fine tuning the general approach with measurements from field samples provided good results for both areas with errors in the recovered weight percent sio 2 of a few percent the map units identified by these techniques and traditional mapping at the hiller mountains demonstrate the continuity of the crystalline rocks from the hiller mountains southward to the white hills supporting the idea that these ranges represent an essentially continuous footwall block below a regional detachment results from the baja california data verify the most recent volcanism to be basaltic andesite

emission spectroscopy of clay minerals and evidence for poorly crystalline aluminosilicates on mars from thermal emission spectrometer data 1 to understand the aqueous history of mars it is critical to constrain the alteration mineralogy of the martian surface previously published analyses of thermal infrared 6 25 m remote sensing data of mars suggest that dark regions have 15 20 clay minerals however near infrared 1 3 m spectral results generally do not identify widespread clay minerals thermal infrared detections of clays on mars are difficult to interpret owing in part to the relative paucity of published spectral analyses of clay minerals and clay bearing materials using similar spectra thermal infrared emission spectra in this study we present an analysis of the thermal emission spectral features 6 25 m or 400 1650 cm 1 of a suite of clay mineral reference materials and clay bearing rocks linking their spectral features to the crystal chemical properties of the clays on the basis of this context provided by the emission spectral analysis of clay minerals and clay bearing rocks we reconsider the evidence for clay minerals on mars from thermal emission spectrometer tes results we propose that global scale clay abundances determined from tes probably represent a geologically significant surface component though they may actually correspond to poorly crystalline aluminosilicates with similar si o ratios to clay minerals 0 3 0 4 rather than well crystalline clays if clay minerals or clay like materials on mars are poorly crystalline and or dessicated they may be detectable in the thermal infrared but not easily detected with near infrared data sets

three dimensional velocity structure in northern california coast ranges from inversion of local earthquake arrival times abstract the three dimensional p wave velocity structure in the upper crust in the northern california coast ranges from santa rosa to ukiah is obtained by simultaneous inversion of local earthquake and refraction travel time data for velocity and hypocentral parameters in this region where there are lateral heterogeneities the three dimensional inversion provides important results not found in two dimensional refraction studies the medium is parameterized with velocities at the intersections gridpoints of a nonuniform three dimensional grid travel times are calculated with approximate ray tracing along arcuate paths which are reasonable for lateral distances less than 45 km inversions with 5 to 10 and 2 to 3 km gridspacing achieved 80 per cent decreases in data variance the inversion with 2 to 3 km gridspacing reduced the rms residual level to approximately the level of timing error anomalously low velocities to at least 6 km depth are found along the maacama and healdsburg rodgers creek hrc fault zones the low velocity region is widest at the en echelon junction of the maacama and hrc fault zones low velocities are associated with the clear lake basin where there is a thick sequence of volcanics interbedded with sedimentary deposits there is a high velocity body located southeast of the geysers between the maacama and collayomi fault zones which may be associated with igneous intrusives or high grade metamorphism related to an underlying inferred partial melt body modeled in previous teleseismic travel time studies there is some indication in the vapor dominated geothermal reservoir of lower velocities relative to surrounding water saturated rock as has been shown in some laboratory experiments hypocenter locations obtained in the inversion show little variation from hypocenters obtained through inversion for one dimensional velocity model and station corrections for the inversion with 2 to 3 km gridspacing however some groups of events become more tightly clustered

tomographic inversion of local earthquake data from the hengill grensdalur central volcano complex iceland parameters is generally low however a quantitative analysis of resolution provides an unambiguous assessment of well resolved volumes within the better resolved regions of the model the averaging volumes are 1 2 km and 2 4 km in vertical and horizontal extent respectively results of tomographic inversion image three distinct bodies of anomalously high velocity two of these extend from near the surface to a depth of about 3 km these high velocity volumes are located directly beneath the surface expressions of the extinct grensdalur volcano and the extinct husmuli basalt shield the third high velocity structure occurs in the depth range of 3 4 km but does not extend to the surface these three high velocity bodies are interpreted to be solidified magmatic intrusions relatively low velocities underlay limited portions of the trace of the present accretionary axis and a low velocity body is imaged in the roots of the active hengill volcano the volume of lower velocities located beneath the surface expression of the hengill volcano is interpreted to be a region of partial melt

thermal and near infrared analyses of central peaks of martian impact craters evidence for a heterogeneous martian crust central peaks of impact craters contain materials exhumed from depth and therefore investigation of these materials provides clues to subsurface geology and mineralogy a global spectral survey of central peaks of martian impact craters between 10 and 200 km diameter was completed using mars odyssey thermal emission imaging system themis data twenty six central peaks with distinctive spectral signatures from surrounding plains were identified and characterized with thermal infrared and visible near infrared data the distribution of spectrally distinct central peaks sdcps shows some degree of regional clustering with most craters found in western noachis terra tyrrhena terra within the northern rim of hellas basin and fewer in the northern lowlands with the exception of four craters in western noachis terra sdcps contain only one spectrally distinct unit at themis resolution 100 m pixel the maximum number of spectrally distinct units observed was three in jones and ostrov craters the western noachis terra sdcps may expose crustal stratigraphies of multiple igneous compositions or impact materials from argyre in the highlands most sdcp units are consistent with enrichments in olivine or pyroxene relative to surrounding plains suggesting olivine and pyroxene basaltic lithologies few are olivine and pyroxene poor no spatial trend in spectrally derived compositions of sdcps was observed three sdcps contain themis signatures consistent with high abundances of phyllosilicates which may contain the most phyllosilicate rich lithologies found in central peak associated materials globally

three dimensional p velocity structure in the region of the ms 6 9 irpinia italy normal faulting earthquake abstract we have calculated the three dimensional velocity structure in the epicentral region of the 1980 irpinia southern italy earthquake using thurber s inversion technique for hypocenter and velocity parameters particular care was given to the evaluation of the resolution of the models because of the poor reading accuracy of the analog stations operating at that time we analyzed the averaging vector for each node of the model in order to estimate the degree of smearing within the final tomographic image this approach is suitable for determining the best parametrization to use i e the minimum grid spacing and for evaluating the region where the computed velocities are meaningful the results show that the main rupture occurred along a sharp nw se trending velocity contrast which probably reflects a crustal discontinuity the velocity variations along the fault probably due to lithological heterogeneities account for the complex character of this earthquake based on the velocity distribution at depth the secondary rupture that started about 40 s after the mainshock is interpreted to be the result of reactivation of an old thrust as a normal fault

hydrous minerals on mars as seen by the crism and omega imaging spectrometers updated global view 1 the surface of mars has preserved the record of early environments in which its basaltic crust was altered by liquid water these aqueous environments have survived in the form of hydrological morphologies and alteration minerals including clays and hydrated salts because these minerals probe on earth aqueous environments compatible with biotic activity understanding their formation processes on mars is of great exobiological relevance and also offers insight into earth s now erased ancient water environments using remote sensing we conducted a large scale investigation of the distribution composition age and geomorphic settings of hydrous minerals on mars providing a sharpened global view of the early aqueous environments and their evolution with time aqueous alteration seems to have produced clays on a planetary scale but these are found to be restricted to the oldest observable terrains on mars 4 gyr however very diverse aqueous environments have also been found which suggest widespread complex aqueous settings from the surface to kilometric depths and spanning over 1 gyr by building a robust statistical sample of detections the global trends inferred here attempt to provide a broad view of our current understanding of hydrous minerals on mars and provide context for more localized in depth analyses collectively these trends suggest that at least transient conditions have existed on mars which may have been favorable for pre biotic to biotic activity

upper crustal structure of the benevento area southern italy fault heterogeneities and potential for large earthquakes summary the benevento region is part of the southern apennines seismogenic belt which experienced large destructive seismic events both in historical and in recent times the study area lies at the northern end of the irpinia fault which ruptured in 1980 with a ms 6 9 normal faulting event which caused about 3000 casualties the aims of this paper are to image lateral heterogeneities in the upper crust of the benevento region and to try to identify the fault segments that are expected to generate such large earthquakes this work is motivated by the recognition that lithological heterogeneities along major fault zones inferred from velocity anomalies reflect the presence of fault patches that behave differently during large rupture episodes in this paper we define the crustal structure of the benevento region by using the background seismicity recorded during 1991 and 1992 by a local seismic array these data offer a unique opportunity to investigate the presence of structural discontinuities of a major seismogenic zone before the occurrence of the next large earthquake the main result that we obtained is the delineation of two nw trending high velocity zones hvzs in the upper crust beneath the matese limestone massif these high velocities are interpreted as high strength regions that extend for 30 40 km down to at least 12 km depth the correspondence of these hvzs with the maximum intensity regions of historical earthquakes 1688 ad 1805 ad suggests that these anomalies delineate the extent of two fault segments of the southern apenninic belt capable of generating m 6 5 7 earthquakes the lateral offset observed between the two segments from tomographic results and isoseismal areas is possibly related to transverse right lateral faults

active airborne infrared laser system for identification of surface rock and minerals emissivity and reflectivity in the thermal infrared spectral region 8 13 m may be used to discriminate among rocks and minerals although considerable success has been achieved in remote sensing classification of rock types based on emissivity measurements made with nasa s thermal infrared multispectral scanner tims classification based on reflectivity offers several advantages much narrower bandwidths are used higher signal to noise ratios are possible and measurements are little affected by surface temperature as a demonstration an airborne co2 laser instrument was flown along the margin of death valley california measurements of spectral reflectance collected with this device were compared with emissivity measurements made with the tims data from either instrument provided the means for recognizing boundaries between geologic units including different rock types and fan surfaces of different ages

from velocity and attenuation tomography to rock physical modeling inferences on fluid driven earthquake processes at the irpinia fault system in southern italy we retrieve 3 d attenuation images of the crustal volume embedding the fault system associated with the destructive ms 6 9 1980 irpinia earthquake by tomographic inversion of t measurements a high qp anomaly is found to be correlated with the 1980 fault geometry while the qs model shows regional scale variations related to the ne edge of the uplifted pre tertiary limestone an upscaling strategy is used to infer rock properties such as porosity consolidation type of fluid mixing and relative saturation percentage at 8 10 km fault depth we constrain the porosity and consolidation in the ranges 4 5 and 5 9 respectively with the possible fluid mixes being both brine co2 and ch4 co2 the consolidation parameter range indicates high pore pressures at the same depths these results support the evidence for a fracture system highly saturated in gases and a seismicity triggering mechanism at the fault zone which is strongly controlled by fluid induced pore pressure changes

mineralogical composition of sands in meridiani planum determined from mars exploration rover data and comparison to orbital measurements constraints on the mineralogical composition of low albedo low sulfur sands at meridiani planum are determined from mars exploration rover mer opportunity miniature thermal emission spectrometer mini tes mossbauer and alpha proton x ray spectrometer measurements results of this work show that the sand is olivine basaltic in composition with minor amounts of sulfate and a high silica phase glass or secondary amorphous silica measurements from all three instruments indicate that pyroxene is twice as abundant as olivine and that the pyroxene composition is dominated by the low calcium variety the volume abundance of olivine is constrained to be 10 15 results from detailed analyses of mer data are used to ground truth the spectral emissivity and mineral abundances derived from orbit with mars global surveyor tes data tes derived mineral abundances are within 5 of those derived from mer data which is generally within the statistical errors associated with tes derived phase abundances the agreement lends support to global and regional scale variations in mineralogical composition determined from tes data in previous studies an alternative method of least squares minimization is used for modeling the tes and mini tes data the benefits of this method are demonstrated by comparison with conventional least squares techniques previously used by tes data users

mineralogy at meridiani planum from the mini tes experiment on the opportunity rover the miniature thermal emission spectrometer mini tes on opportunity investigated the mineral abundances and compositions of outcrops rocks and soils at meridiani planum coarse crystalline hematite and olivine rich basaltic sands were observed as predicted from orbital tes spectroscopy outcrops of aqueous origin are composed of 15 to 35 by volume magnesium and calcium sulfates a high silica component modeled as a combination of glass feldspar and sheet silicates 20 to 30 and hematite only minor jarosite is identified in mini tes spectra mini tes spectra show only a hematite signature in the millimeter sized spherules basaltic materials have more plagioclase than pyroxene contain olivine and are similar in inferred mineral composition to basalt mapped from orbit bounce rock is dominated by clinopyroxene and is close in inferred mineral composition to the basaltic martian meteorites bright wind streak material matches global dust waterlain rocks covered by unaltered basaltic sands suggest a change from an aqueous environment to one dominated by physical weathering

mineral maps of the moon 1 global maps of the distribution of plagioclase orthopyroxene clinopyroxene and olivine on the moon were derived from radiative transfer analysis of 400 000 clementine uvvis spectra plagioclase inversely correlates with iron while clinopyroxene positively correlates with iron showing these are the major carriers of aluminum and iron respectively the distribution of olivine in the maria agrees with previous studies in the highlands the abundance of olivine is low but ubiquitous at a few percent except within the south pole aitken basin where it is only present in very small exposures in the very anorthositic farside highlands olivine is often the sole mafic mineral the abundance of orthopyroxene is generally low excepting elevated abundances in the nearside highlands and in areas near and within south pole aitken basin mare units with elevated abundances of orthopyroxene are found in some mare and cryptomare deposits distant from the sample return sites

elemental geochemistry of sedimentary rocks at yellowknife bay gale crater mars sedimentary rocks examined by the curiosity rover at yellowknife bay mars were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts no evidence of chemical weathering is preserved indicating arid possibly cold paleoclimates and rapid erosion and deposition the absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low temperature circumneutral ph rock dominated aqueous conditions analyses of diagenetic features including concretions raised ridges and fractures at high spatial resolution indicate that they are composed of iron and halogen rich components magnesium iron chlorine rich components and hydrated calcium sulfates respectively composition of a cross cutting dike like feature is consistent with sedimentary intrusion the geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of mars

composition and thermal inertia of the mawrth vallis region of mars from tes and themis data abstract clay mineral bearing deposits previously discovered on mars with near infrared 0 3 5 m remote sensing data are of major significance for understanding the aqueous history geological evolution and past habitability of mars in this study we analyzed the thermal infrared 6 35 m surface properties of the most extensive phyllosilicate deposit on mars the mawrth vallis area clay mineral bearing units which in visible images appear to be relatively light toned layered bedrock have thermal inertia values ranging from 150 to 460 j m 2 k 1 s 1 2 this suggests the deposits are composed of a mixture of rock with sand and dust at 100 meter scales dark toned materials that mantle the clay bearing surfaces have thermal inertia values ranging from 150 to 800 indicating variable degrees of rockiness or induration of this younger sedimentary or pyroclastic unit thermal emission spectrometer tes spectra of the light toned rocks were analyzed with a number of techniques but none of the results shows a large phyllosilicate component as has been detected in the same surfaces with near infrared data instead tes spectra of light toned surfaces are best modeled by a combination of plagioclase feldspar high silica materials similar to impure opaline silica or felsic glass and zeolites we propose three hypotheses for why the clay minerals are not apparent in thermal infrared data including effects due to surface roughness sub pixel mixing of multiple surface temperatures and low absolute mineral abundances combined with differences in spatial sampling between instruments zeolites modeled in tes spectra could be a previously unrecognized component of the alteration assemblage in the phyllosilicate bearing rocks of the mawrth vallis area tes spectral index mapping suggests that fe mg clays detected with near infrared data correspond to trioctahedral fe2 clay minerals rather than nontronite like clays the average mineralogy and geologic context of these complex interbedded deposits suggests they are either aqueous sedimentary rocks altered pyroclastic deposits or a combination of both

yeosu dinosaur track sites of korea the youngest dinosaur track records in asia abstract eighty two dinosaur trackways were newly discovered in upper cretaceous lacustrine deposits on islands in the vicinity of yeosu korea most dinosaur tracks occur in marginal lake deposits with polygonal desiccation cracks the dinosaur tracks at the yeosu site include 65 ornithopod trackways 16 theropod trackways and one sauropod trackway the prevalence of ornithopod tracks and the limited occurrence of sauropod tracks at the yeosu site evidently reflect decreased sauropod diversity in the upper cretaceous all ornithopod trackways represent bipeds and most of the ornithopod tracks are similar to caririchnium from other sites of the korean peninsula all fossil wood specimens collected in the study area represent conifers three species of cupressaceous and two species of taxodiaceous conifers and a new species except for one which is a discotyledon it is thus inferred that the southwestern part of the korean peninsula was primarily covered with mesic forests with taxodiaceous trees during the late cretaceous the k ar age of the yeosu tracksite is determined as 81 65 ma camapnian to maastrichtian it indicates that the yeosu track site contains the last records of dinosaurs living in asia consequently semi arid palaeoclimatic conditions together with a large lake as a persistent water source and rich vegetation of gymnosperm trees as food resulted in the preservation of abundant dinosaur tracks in the upper cretaceous on the korean peninsula

analysis of phyllosilicate deposits in the nili fossae region of mars comparison of tes and omega data abstract diverse phyllosilicate deposits discovered previously in the nili fossae region with near infrared reflectance data are a window into the complex history of aqueous alteration on mars in this work we used thermal infrared data from the thermal emission spectrometer tes in combination with near infrared data from the observatoire pour la mineralogie l eau les glaces et l activite omega to better constrain the mineralogy and geologic origin of these deposits we developed a tes spectral index for identification of clay minerals which correctly identifies the phyllosilicates in the nili fossae area and points to several other interesting deposits in the syrtis major region however detailed inspection of the tes spectral features of nili fossae phyllosilicates shows a feature at low wavenumbers 350 550 cm 1 that is not an exact match to any specific fe 3 al or mg rich phyllosilicate phase instead the feature is more similar to basaltic glass and may indicate that the phyllosilicates in this region are 1 rich in fe 2 based on similarity to trends seen in laboratory data of clay minerals 2 poorly crystalline extremely disordered and or 3 present within a matrix of actual basalt glass this feature is similar to spectral features seen in altered rocks in the columbia hills region of gusev crater by previous authors by calibrating measured spectral index values against mathematical spectral mixtures of typical martian dark surfaces and known abundances of alteration minerals we are able to estimate an enrichment in abundance of alteration minerals in the altered surfaces many dark noachian deposits in the nili fossae area are enriched phyllosilicates by 20 30 10 15 relative to dark volcanic surfaces in the same region the distribution and abundance of these phases indicates that alteration in the region was pervasive but did not completely erase the original mineralogy of what was likely an fe rich basalt protolith as a group the nili fossae phyllosilicate deposits are fundamentally different from those found in the mawrth vallis region nili fossae deposits have strong thermal infrared features related to admixed pyroxene plagioclase and occasionally olivine whereas the mawrth vallis deposits contain no mafic minerals comparison of tes and omega data also illustrates some more general differences between the datasets including the impact of physical character of the martian surface on detectability of minerals in each spectral range

surface mineralogy of martian low albedo regions from mgs tes data implications for upper crustal evolution and surface alteration 1 mars global surveyor thermal emission spectrometer mgs tes data are used to derive the modal mineralogy of spectrally distinct martian low albedo regions and to identify spatial trends in mineralogic assemblages results from this work are consistent with the major results of previous spectroscopic studies 1 plagioclase and clinopyroxene are the dominant minerals of most southern highlands regions 2 the northern plains exhibit the lowest pyroxene abundance within martian low albedo regions and 3 the highest concentrations of high silica phase s are found in the northern plains solis planum and a few southern high latitude regions low albedo regions may be classified into four units on the basis of relative abundances of plagioclase pyroxene and high silica phase s unit distributions between 45 latitude exhibit moderate correlation with distinct provinces e g syrtis major aonium sinus defined by large scale morphology elevation and to some extent surface age suggesting that the spectral and compositional differences between these units are more strongly controlled by original bedrock mineralogy than by surface atmosphere interactions and alteration syrtis major exhibits a difference in mineralogy from the surrounding highlands suggesting a differing degree of fractional crystallization assimilation or source region composition areas with thick crust near the tharsis plateau exhibit lower abundances of olivine and greater plagioclase pyroxene ratios than surrounding highland terrains suggesting that magmas in this region may have undergone increased olivine fractionation regions where surface alteration is more likely to be the primary control on observed spectral signatures are the high latitude areas 45 where globally surfaces dominated by high silica phase s are most commonly found

subaerial lenticular cracks in cretaceous lacustrine deposits korea abstract in the cretaceous lacustrine deposits of the yucheon group of korea lenticular cracks are commonly found in the interlaminated to thinly interbedded sandstone mudstone facies the general shape of the cracks is variable many having lenticular shape incomplete development and random distribution in places cracks are orthogonally intersected or polygonally interlinked elongate rhombic to subrhombic hemipyramidal bladed prismatic or swallow tail twin shaped cracks and square cuboid or rectangular sand patches are associated with the lenticular cracks which suggests the former presence of soluble evaporite minerals in the unit layers of the crack bearing deposits sandstones have sharp bases and grade upward into mudstones planar lamination low angle cross lamination and small scale ripples are present mudstone chips some of which preserve the cracks are present in the sandstones these crack bearing layers are interpreted as sheetflood deposits on the basis of these characteristics the lenticular cracks of the yucheon lacustrine deposits in korea are interpreted as subaerial desiccation cracks formed on dried mudflats the similarity between the yucheon lenticular cracks and those described from the devonian lacustrine deposits in scotland astin and rogers 1991 suggests that subaerial lenticular cracks associated with evaporite minerals are not rare in geologic time and space

determining the modal mineralogy of mafic and ultramafic igneous rocks using thermal emission spectroscopy the modal mineralogies of 20 mafic and ultramafic igneous rocks were determined from their thermal infrared emission spectra using a linear deconvolution approach which uses a library of end member mineral spectra to model a bulk rock spectrum over 90 of the modes obtained from thermal emission spectra agree with modes obtained by traditional optical analyses to within the stated error of the optical analyses 5 15 vol library spectra of several compositions within a solid solution series e g plagioclase feldspars labradorite and bytownite were commonly used in each best fit model and are assumed to represent in combination a composition in the rock for which an identical mineral spectrum was unavailable in the library the accuracy of this assumption was evaluated by calculating a weighted average solid solution composition for plagioclase and or pyroxenes from the library minerals used in the model best fit of 14 rocks and comparing these compositions to the actual chemistries measured by electron microprobe or the optically estimated an the derived solid solution compositions are generally within 10 15 an or mg of the measured composition modal data derived from the spectra via the deconvolution were summed and converted to weight percent wt oxides for comparison to standard bulk chemistry data sio2 al2o3 and na2o k2o were generally slightly overestimated and feo and mgo were typically slightly underestimated modes and wt oxides were plotted on standard rock type classification diagrams and provide broadly accurate classifications demonstrating that the linear deconvolution technique is successful at deriving useful mineralogical information from thermal infrared emission spectra of bulk rock samples furthermore convolution of the laboratory data to spectral resolutions comparable to remote sensing instruments specifically the mars global surveyor thermal emission spectrometer demonstrates only a 5 vol increase in modal uncertainty for minerals present in abundances 10 vol this study thus provides a strong foundation for the application of this technique to mafic igneous sample spectra from both laboratory and remote sensing instruments

hydrogeochemical processes in clastic sedimentary rocks south korea a natural analogue study of the role of dedolomitization in geologic carbon storage abstract for long term mineral trapping of sequestered co 2 in deep saline aquifers base cations such as ca 2 and mg 2 are essential as a natural analogue study of geologic carbon storage in deep aquifers hosted in sedimentary formations we examined the hydrochemistry of sulfate rich up to 1140 mg l so 4 2 and moderately high p co 2 10 1 1 to 10 2 4 atm groundwater in a cretaceous non marine sedimentary basin in south korea with the objective to elucidate water rock interactions controlling the concentrations and behavior of base cations principal component analysis of the acquired hydrochemical data indicated that dissolution of carbonates calcite and dolomite and evaporite minerals halite and gypsum controls the chemical composition of groundwater resulting in substantial increases of the concentration s of ca 2 mg 2 na cl so 4 2 and total dissolved solids tds in deep groundwater na versus cl and ca 2 mg 2 versus hco 3 so 4 2 plots provided evidence for dissolution of halite and gypsum progressively increasing 34 s values of dissolved so 4 2 from 15 1 to 19 2 with increasing sulfate concentrations indicated gypsum dissolution ion ion plots esp mg 2 ca 2 ca 2 so 4 2 and mg 2 so 4 2 and saturation indices of calcite dolomite and gypsum suggest that the groundwater chemistry esp the concentrations of ca 2 and mg 2 is controlled by dedolomitization driven by gypsum dissolution groundwater in the study area does not reach complete equilibrium with respect to calcite and dolomite because of gypsum dissolution which controls the mg 2 ca 2 ratios of groundwater continued calcite precipitation triggered by an excess ca supply from gypsum dissolution reduces the concentrations of dissolved inorganic carbon dic in groundwater the increase of 13 c dic values from 11 1 to 6 5 concomitantly with increasing sulfate concentration was explained via geochemical modeling by dedolomitization under the rate constant ratio of about 0 038 between dolomite and calcite the model results agree well with the observed mg 2 ca 2 ratios and further suggest a potential increase of the void volume in the aquifer through dedolomitization by about 0 72 cm 3 l based on this analogue we suggest that dedolomitization in concert with dissolution of gypsum may constitute an important process releasing base cations for mineral trapping of injected co 2 in non marine clastic sedimentary strata containing carbonates and gypsum in south korea and elsewhere

compositional stratigraphy of clay bearing layered deposits at mawrth vallis mars phyllosilicates have previously been detected in layered outcrops in and around the martian outflow channel mawrth vallis crism spectra of these outcrops exhibit features diagnostic of kaolinite montmorillonite and fe mg rich smectites along with crystalline ferric oxide minerals such as hematite these minerals occur in distinct stratigraphic horizons implying changing environmental conditions and or a variable sediment source for these layered deposits similar stratigraphic sequences occur on both sides of the outflow channel and on its floor with al clay bearing layers typically overlying fe mg clay bearing layers this pattern combined with layer geometries measured using topographic data from hirise and hrsc suggests that the al clay bearing horizons at mawrth vallis postdate the outflow channel and may represent a later sedimentary or altered pyroclastic deposit that drapes the topography