mineralogy and geochemistry of alluvium contaminated by metal mining in the rio tinto area southwest spain the rio tinto in sw spain drains cu and pyrite mines which have been in operation since at least the bronze age extensive metal mining especially from 1873 to 1954 has resulted in contamination of the rio tinto alluvium with as cu pb ag and zn x ray diffraction xrd wavelength dispersive x ray mapping scanning electron microscope petrography and x ray energy dispersive edx analysis has revealed that 4 major groups of contaminant metal and as bearing minerals including sulphides fe as oxides fe oxides hydroxides oxyhydroxides and fe oxyhydroxysulphates occur in the alluvium sulphide minerals including pyrite chalcopyrite arsenopyrite and sphalerite occur in alluvium near the mining areas iron hydroxides and oxyhydroxides such as goethite and possibly ferrihydrite occur in cements in both the mining areas and alluvium downstream and carry minor amounts of as cu and zn iron oxyhydroxysulphates including jarosite plumbojarosite and possibly schwertmannite are the most common minerals in alluvium downstream of the mining areas and are major hosts of cu pb zn and of as next to the fe as minerals this work and other field observations suggest that 1 the extreme acidity and elevated metal concentrations of the river water will probably be maintained for some time due to oxidation of pyrite and other sulphides in the alluvium and mine waste tips and from formation of secondary oxide and oxyhydroxysulphates 2 soluble fe oxyhydroxysulphates such as copiapite which form on the alluvium are a temporary store of contaminant metals but are dissolved during periods of high rainfall or flooding releasing contaminants to the aqueous system 3 relatively insoluble fe oxyhydroxysulphates and hydroxides such as jarosite and goethite may be the major long term store of alluvial contaminant metals and 4 raising river ph will probably cause precipitation of fe oxyhydroxides and oxides hydroxides oxyhydroxides and thus have a positive effect on water quality but this action may destabilise some of these contaminant metal bearing minerals releasing metals back to the aqueous system

diagenetic layers in the upper walls of valles marineris mars evidence for drastic climate change since the mid hesperian a packet of relatively resistant layers totaling 400 m thickness is present at the tops of the chasma walls throughout valles marineris the packet consists of an upper dark layer 50 m thick a central bright layer 250 m thick and a lower dark layer 100 m thick the packet appears continuous and of nearly constant thickness and depth below ground surface over the whole valles system 4000 km e w 800 km n s independent of elevation 3 10 km and age of plateau surface noachian through upper hesperian the packet continues undisturbed beneath the boundary between surface units of noachian and hesperian ages and continues undisturbed beneath impact craters transected by chasma walls these attributes are not consistent with layer formation by volcanic or sedimentary deposition and are consistent with layer formation in situ i e by diagenesis during or after upper hesperian time diagenesis seems to require the action of aqueous solutions in the near subsurface which are not now stable in the valles marineris area to permit the stability of aqueous solutions mars must have had a fairly dense atmosphere 1 bar co2 when the layers formed obliquity variations appear to be incapable of producing such a massive atmosphere so late in mars history

effects of h2o ph and oxidation state on the stability of fe minerals on mars 1 on mars there is evidence that solutions may have been present on the surface episodically in the past these solutions were derived by weathering minerals such as olivine and sulfides found in mafic ultramafic rocks and possibly sulfates and meteorite fragments upon removal of water and or supersaturation of solutions secondary minerals formed we present a theoretical model for the formation of the solutions and the subsequent precipitation of fe bearing phases the first fe bearing phases to weather via oxidation are sulfides troilite or pyrrhotite which produce secondary fe hydr oxides or fes 2 pyrite or marcasite and fe 2 sulfates such as melanterite melanterite may be replaced by fe sulfates that have decreasing h 2 o 3fe 3 2fe 2 increasing oxidation and increasing bulk oh oh 2so 4 at meridiani planum the presence of jarosite indicates that the solutions were oxidized with ph 4 5 the solutions were likely fe mg ca s04 cl rich and precipitated fe hydr oxides fe phosphates fe sulfates with low oh oh so 4 ca mg sulfates and possible halides along with si rich phases the minerals indicating an acid environment were preserved by either removing components such as salts or water from the system e g in dust storms or episodic aqueous events isolating the mineral surfaces from fluids using disequilibrium processes or a combination at other localities jarosite is below detection limits and schwertmannite may be present if schwertmannite is present the solution had near neutral ph 4 ph 10 and fe hydr oxides would have crystallized rapidly leaving mg na ca s04 cl rich solutions that likely precipitated ca phosphates ca mg na sulfates fe sulfates with moderate high oh oh so 4 halides si rich phases and possibly fe mg ca carbonates

experimental study of acid sulfate alteration of basalt and implications for sulfate deposits on mars 1 acid sulfate alteration of basalt by so2 bearing volcanic vapors has been proposed as one possible origin for sulfate rich deposits on mars to better define mineralogical signatures of acid sulfate alteration laboratory experiments were performed to investigate alteration pathways and geochemical processes during reaction of basalt with sulfuric acid pyroclastic cinders composed of phenocrysts including plagioclase olivine and augite embedded in glass were reacted with sulfuric acid at 145 c for up to 137 days at a range of fluid rock ratios during the experiments the phenocrysts reacted rapidly to form secondary products while the glass was unreactive major products included amorphous silica anhydrite and fe rich natroalunite along with minor iron oxides oxyhydroxides probably hematite and trace levels of other sulfates at the lowest fluid rock ratio hexahydrite and an unidentified fe silicate phase also occurred as major products reaction path models indicated that formation of the products required both slow dissolution of glass and kinetic inhibitions to precipitation of a number of minerals including phyllosilicates and other aluminosilicates as well as al and fe oxides oxyhydroxides similar models performed for martian basalt compositions predict that the initial stages of acid sulfate alteration of pyroclastic deposits on mars should result in formation of amorphous silica anhydrite fe bearing natroalunite and kieserite along with relict basaltic glass in addition analysis of the experimental products indicates that fe bearing natroalunite produces a mossbauer spectrum closely resembling that of jarosite suggesting that it should be considered an alternative to the component in sulfate rich bedrocks at meridiani planum that has previously been identified as jarosite

scandinavian glacial and climatic fluctuations during the holocene abstract historical documents and lichenometric studies give a detailed picture of the little ice age in scandinavia there was a large advance in norway which has been dated at a few places to 1750 small readvances during the retreat occurred around a d 1780 1810 1840 1850 1850 1870 1890 1910 and 1930 in sweden most of these advances have been recognized and in addition extensive advances are dated by lichenometry to around a d 1600 1650 and 1700 1720 soils buried beneath moraines often yield radiocarbon dates that are much too old methods dependent on these must therefore be used with care evidence for pre little ice age advances are often considered equivocal the most reliable information is probably provided by studies of lacustrine sediments combining information from all sources the most significant pre little ice age glacier advances most likely occurred in 7 5 5 1 4 5 3 2 2 8 2 2 1 9 and 1 5 1 1 radiocarbon ka bp advances that were less extensive or for which there is less evidence occurred around 6300 5600 2500 940 600 560 and 380 bp

sedimentary silica on mars terrestrial planetary surfaces other than earth are overwhelmingly basaltic in character because of this among the most intriguing and significant results from recent studies of mars are the occurrences of high silica rocks at the pathfinder site and orbital thermal emission spectroscopy evidence for a global petrological dichotomy with andesites dominating the entire northern hemispheric plains however during the alteration of basalt under a wide variety of pressure temperature and fluid conditions silica is highly mobile and chemical and or mineralogical relationships among martian soils and other surface deposits suggest the likelihood that sedimentary silica phases would have formed during surficial alteration processes accordingly the redistribution of sedimentary silica needs to be considered in interpreting at least some of the high silica features seen on mars

sublacustrine precipitation of hydrothermal silica in rift lakes evidence from lake baringo central kenya rift valley abstract many lakes in volcanic regions are fed by hot springs that in some basins can contribute a large percentage of the annual recharge especially during times of aridity it is important to recognize any contemporary hydrothermal contribution in paleoenvironmental reconstruction of lake basins because recharge from thermal waters can potentially confuse paleoclimatic signals preserved in the lacustrine sedimentary record hot spring deposits travertine sinter provide the most tangible evidence for thermal recharge to lakes although subaerial spring deposits have been widely studied lacustrine thermal spring deposits especially sublacustrine siliceous sinters remain poorly known detailed field petrographic and scanning electron microscope sem studies have been made of fossil sublacustrine sinter exposed at soro hot springs along the northeastern shoreline of ol kokwe a volcanic island in lake baringo kenya modern hot springs at soro which discharge na hco3 cl waters from a deep reservoir 180 c have thin 1 10 mm friable microbial silica crusts around their subaerial vents but thicker 1 cm sinter deposits are not forming the fossil sinter which is present as intergranular cements and crusts in littoral conglomerates and sandstones is composed mainly of opaline silica opal a three types of fossil sinter are recognized 1 massive structureless silica which fills intergranular pores and forms crusts up to 5 cm thick 2 pore lining silica some of which is isopachous and 3 laminated silica crusts which formed mainly on the upper surfaces of detrital particles all three types contain well preserved diatoms including lacustrine planktonic forms microbial remains mainly filamentous and coccoid bacteria including cyanobacteria and extracellular polymeric gels are locally abundant in the opaline silica together with detrital clays and thin laminae composed of authigenic chlorite most of the hydrothermal silica precipitated when the thermal springs were submerged by fresh lake water silica precipitated upon rapid cooling of thermal 90 c waters at and just below their interface with the overlying cooler 25 c lake waters microbial mats locally acted as a filter that limited mixing and rapid dilution of the thermal fluids some of the silica originally may have been soft and partly gelatinous planktonic diatoms and detrital clay rained down then became incorporated in the amorphous silica following a fall in lake level the opal a lithified and partly altered to cristobalite opal c and chalcedony the lowest fossil sinters were later encrusted by calcite stromatolites with calcite and quartz forming late pore filling cements the age of the sublacustrine sinters is unknown but some of the deposits could date back to the late pleistocene similar conglomerates cemented by hydrothermal silica are present along fault lines at neighbouring lake bogoria such rocks may provide evidence for deep hot fluid recharge to lakes when encountered in the geological record

mro crism retrieval of surface lambert albedos for multispectral mapping of mars with disort based radiative transfer modeling phase 1 using historical climatology for temperatures aerosol optical depths and atmospheric pressures we discuss the disort based radiative transfer pipeline ldquocrism lambertalbrdquo for atmospheric and thermal correction of mro crism data acquired in multispectral mapping mode 200 m pixel 72 spectral channels currently in this phase one version of the system we use aerosol optical depths surface temperatures and lower atmospheric temperatures all from climatology derived from mars global surveyor thermal emission spectrometer mgs tes data and from surface altimetry derived from mgs mars orbiter laser altimeter mola the disort based model takes the dust and ice aerosol optical depths scaled to the crism wavelength range the surface pressures computed from mola altimetry mgs tes lower atmospheric thermometry and viking based pressure climatology the surface temperatures the reconstructed instrumental photometric angles and the measured i f spectrum as inputs and then a lambertian albedo spectrum is computed as the output the lambertian albedo spectrum is valuable geologically because it allows the mineralogical composition to be estimated here i f is defined as the ratio of the radiance measured by crism to the solar irradiance at mars divided by pi if there was no martian atmosphere i f divided by the cosine of the incidence angle would be equal to the lambert albedo for a lambertian surface after discussing the capabilities and limitations of the pipeline software system we demonstrate its application on several multispectral data cubes particularly the outer reaches of the northern ice cap of mars the tyrrhena terra area that is northeast of the hellas basin and an area near the landing site for the phoenix mission in the northern plains for the icy spectra near the northern polar cap aerosols need to be included in order to properly correct for the co2 absorption in the h2o ice bands at wavelengths near 2 0 mum in future phases of software development we intend to use crism data directly in order to retrieve the spatiotemporal maps of aerosol optical depths surface pressure and surface temperature this will allow a second level of refinement in the atmospheric and thermal correction of crism multispectral data

topography of valles marineris implications for erosional and structural history compilation of a simplified geologic geomorphic map onto digital terrain models of the valles marineris permitted an evaluation of elevations in the vicinity of the troughs and the calculation of depth of troughs below surrounding plateaus thickness of deposits inside the troughs volumes of void spaces above geologic geomorphic units and volumes of deposits the central troughs north ophir north and central candor and north melas chasmata lie as much as 11 km below the adjacent plateaus in ophir and candor chasmata interior layered deposits reach 8 km in elevation if the deposits are lacustrine and if all troughs were interconnected lake waters standing 8 km high would have spilled out of coprates chasma onto the surrounding plateaus having surface elevations of only 4 5 km in this case interior deposits above about 4 km in the central troughs would not be lacustrine they could be volcanic on the other hand the troughs may not have been interconnected at the time of interior deposit emplacement they may have formed isolated ancestral basins the existence of such basins is supported by independent structural and stratigraphic evidence the ancestral basins may have eventually merged perhaps through renewed faulting to form northern subsidiary troughs in ophir and candor chasmata and the coprates north melas ius graben system the peripheral troughs are only 2 5 km deep shallower than the central troughs they may have formed from a combination of erosional collapse and structural activity chaotic terrain is seen in the peripheral troughs near a common contour level of about 4 km on the adjacent plateaus which supports the idea of release of water under artesian pressure from confined aquifers the layered deposits in the peripheral troughs may have formed in isolated depressions that harbored lakes and predated the formation of the deep outflow channels if these layered deposits are of volcanic origin they may have been emplaced beneath ice in the manner of table mountains areal and volumetric computations show that erosion widened the troughs by about one third and that deposits occupy one sixth of the interior space even though the volume eroded is larger than the volume deposited topographic and geologic considerations imply that material eroded from trough walls was probably part of the interior layered deposits but not their sole source additional material may have come from subterranean piping from reworking of local disintegration products on the floors such as chaotic materials or from eolian influx but overall it is likely that the additional material is volcanic and that it forms mostly the upper more diversely bedded layers of the interior deposits

recognition of minor constituents in reflectance spectra of allan hills 84001 chips and the importance for remote sensing on mars reflectance spectra of splits 92 and 271 from the martian meteorite allan hills alh 84001 are presented and analyzed in this paper although the visible and infrared spectra of both chips show that the dominant mineralogy is low ca pyroxene the focus here is on identification of the minor constituents infrared spectra measured at multiple spots along the surface of chips 92 and 271 show subtle spectroscopic variations due to changes in the low ca pyroxene texture and composition and to the presence of secondary minerals absorption bands observed near 0 93 and 1 95 m are characteristic of low ca pyroxene strong mid infrared reststrahlen bands are observed near 9 and 19 5 m in all surface spectra and additional bands near 7 10 5 11 4 17 8 20 5 and 23 m are variable depending on the low ca pyroxene texture and the presence of secondary minerals selected spectra exhibit carbonate features near 4 6 4 7 1 and 11 3 m detailed analysis of these carbonate features indicates the presence of mg fe carbonate which is consistent with petrographic studies many of these spectra with strong carbonate features exhibit a magnetite feature near 17 9 m and a shoulder near 20 5 m that cannot be uniquely ascribed to one mineral spectroscopic identification of the minor carbonate and magnetite minerals in this probable piece of mars indicates that detection of small amounts of these minerals of possible biological significance will be possible using infrared hyperspectral analyses of the martian surface also of importance for remote sensing on mars is the result that mg fe and mg fe carbonates in a low ca pyroxene matrix should be distinguishable from one another in the spectral region measured by the thermal emmitance spectrometer tes

related magma ice interactions possible origins of chasmata chaos and surface materials in xanthe margaritifer and meridiani terrae mars abstract we examine here the close spatial and temporal associations among several unique features of xanthe and margaritifer terrae specifically the valles marineris troughs or chasmata and their interior deposits chaotic terrain the circum chryse outflow channels and the subdued cratered material that covers xanthe margaritifer and meridiani terrae though previous hypotheses have attempted to explain the origin of individual features or subsets of these we suggest that they may all be related all of these features taken together present a consistent scenario that includes the processes of sub ice volcanism and other magma ice interactions results of intrusive events during late noachian to early amazonian times

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

a proposed mechanism for the growth of chalcedony the structural disparities that distinguish chalcedony from macrocrystalline quartz suggest that different crystallization mechanisms are operative during the growth of these two forms of silica although the paragenesis of chalcedony has provoked marked disagreement among researchers a review of previous studies supports the idea that chalcedony can precipitate from slightly saturated aqueous solutions at relatively low temperatures 100 c these conditions for deposition suggest a model for chalcedony crystallization that involves the assembly of short chain linear polymers via bridging silica monomers this assembly occurs through a spiral growth mechanism activated by a screw dislocation withb n 2 110 wheren is an integer the proposed model can account for a number of peculiarities that have been observed in chalcedony at the microstructural scale such as 1 the direction of fiber elongation along 110 rather than 001 2 the periodic twisting of chalcedony fibers about 110 3 the high density of brazil twin composition planes 4 the common intergrowth of moganite within chalcedony

light toned strata and inverted channels adjacent to juventae and ganges chasmata mars 1 light toned layered deposits on the plains adjacent to juventae and ganges chasmata have been identified and analyzed with several instruments onboard the mars reconnaissance orbiter including hirise ctx and crism beds exhibit variations in brightness color polygonal fracturing and erosional properties that are not seen in light toned layered deposits within the chasmata at both juventae and ganges the light toned layered deposits along the plains have associated features we interpret as fluvial including sinuous ridges inverted channels that exhibit light toned layering and an extensive valley system for the ganges deposit the strong correlation between the inverted channels and light toned layered deposits suggests an association with fluvial lacustrine processes although pyroclastic and eolian activity may also be involved in their emplacement the identification of potential fluvial lacustrine layered deposits and associated valley networks suggests surface water flow in the valles marineris region that occurred for sustained periods during the hesperian 3 7 3 0 gyr

possible juventae chasma subice volcanic eruptions and maja valles ice outburst floods on mars implications of mars global surveyor crater densities geomorphology and topography 1 this article discusses image topographic and spectral data from the mars global surveyor mgs mission that provide new information concerning the surface age geomorphology and topography of the juventae chasma maja valles system our study utilizes data from two instruments on board mgs images from the mars orbiter camera moc and topography from the mars orbiter laser altimeter mola within maja valles we can now observe depositional bars with megaripples that unequivocally show catastrophic floods occurred in the channel viking impact crater densities indicated the chasma and channel floor areas were all one age late hesperian to amazonian however moc data indicate a marked difference in densities of small craters between juventae chasma maja valles and the channel debouchment area in chryse planitia basin although other processes may contribute to crater variability young resurfacing events in the chasma and episodes of recent erosion at maja valles channel head may possibly account for the disparate crater densities along the chasma channel system relatively young volcanic eruptions may have contributed to resurfacing as in juventae chasma a small possible volcanic cone of young dark material is observed moc data also indicate previously unknown interior layered deposit mounds in the chasma that indicate at least two periods of mound formation finally mola topography shows that the entire floor of the chasma lies at the same elevation as the channel debouchment area in chryse basin resulting in a 3 km high barrier to water flow out of the chasma blocked ponded water would rapidly freeze in the current and likely past climate of mars for catastrophic flow to occur in maja valles some process is required to melt ice and induce floods out of the chasma we suggest subice volcanic eruption and calculate estimates of water discharges and volumes that these eruptions might have produced

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

opaline silica in young deposits on mars high spatial and spectral resolution reflectance data acquired by the mars reconnaissance orbiter compact reconnaissance imaging spectrometer for mars crism instrument reveal the presence of h 2o and sioh bearing phases on the martian surface the spectra are most consistent with opaline silica and glass altered to various degrees confirming predictions based on geochernicall experiments and models that amorphous silica should be a common weathering product of the basaltic martian crust these materials are associated with hydrated fe sulfates including h 3o bearing jarosite and are found in finely stratified deposits exposed on the floor of and on the plains surrounding the valles marineris canyon system stratigraphic relationships place the formation age of these deposits in the late hesperian or possibly the amazonian implying that aqueous alteration continued to be an important and regionally extensive process on mars during that time

interior trough deposits on mars subice volcanoes widespread several kilometer thick successions of layered deposits occur as mounds that partly fill the troughs or chasmata that compose the valles marineris on mars like terrestrial subice volcanoes the layered deposits occur in a volcano tectonic setting within basins that may have held ponded water or ice on the basis of their dimensions morphologies and associated catastrophic floods and other geologic events as shown in viking and new mars global surveyor mgs data sets we suggest that the interior deposits are volcanic in origin and possibly generated by subice eruptions a tuya origin for the mounds can explain the lack of external sediment mound heights that can rival the plateau local flat topped mesas morphologically distinct mounds of different ages horizontal to steep dips fine grained materials indications of rare volcanic vents and lava flows and spectral composition the extremely diverse layering of west candor chasma and possible volcanic cones in melas may have formed by related subaerial eruptions consistent with the suggestion that interior deposits are eroding out of the wall rock some deposits could have been erupted from sites along the walls

mineralogy of juventae chasma sulfates in the light toned mounds mafic minerals in the bedrock and hydrated silica and hydroxylated ferric sulfate on the plateau 1 juventae chasma contains four light toned sulfate bearing mounds denoted here as a d from west to east inside the trough mafic outcrops at the base of the mounds and in the wall rock and light toned layered deposits of opal and ferric sulfates on the plateau hyperspectral visible near infrared compact reconnaissance imaging spectrometer for mars crism spectra were used to identify monohydrated and polyhydrated sulfate phs outcrops of layered material on the bright mounds most of the monohydrated sulfate signatures closely resemble those of szomolnokite feso4 h2o characterized by a water band near 2 08 m while some areas exhibit spectral features more similar to those of kieserite mgso4 h2o with a band centered closer to 2 13 m the largest phs outcrops occur on the top of mound b and their spectral features are most consistent with ferricopiapite melanterite and starkeyite but a specific mineral cannot be uniquely identified at this time coordinated analyses of crism maps mars orbiter laser altimeter elevations and high resolution imaging science experiment images suggest that mounds a and b may have formed together and then eroded into separate mounds while mounds c and d likely formed separately mafic minerals low ca pyroxene high ca pyroxene and olivine are observed in large 2 10 km wide outcrops in the wall rock and in smaller outcrops 50 500 m across at the floor of the canyon most of the wall rock is covered by at least a thin layer of dust and does not exhibit strong features characteristic of these minerals the plateau region northwest of juventae chasma is characterized by an abundance of light toned layered deposits one region contains two spectrally unique phases exhibiting a highly stratified terraced pattern crism spectra of one unit eroded into swirling patterns with arc like ridges exhibit a narrow 2 23 m band assigned to hydroxylated ferric sulfate a thin layer of a fractured material bearing an opaline silica phase is observed at the contact between the older plateau unit and the younger hydroxylated ferric sulfate bearing light toned layered deposits hydrothermal processes may have produced an acidic environment that fostered formation of the hydrated silica and hydroxylated ferric sulfate units

geomorphic study of fluvial landforms on the northern valles marineris plateau mars 1 fluvial landforms are observed on the plateau near echus chasma and other locations on the valles marineris plateau using high resolution 10 to 50 m pixel mars express images and topography branching valleys have a 20 to 100 m deep v shape profile typical of fluvial processes their incision occurred in a thin 150 m and weak dark unit that overlies the plateau basement the valleys are distributed close to watershed boundaries as expected for overland flows and different from pure glacial or hydrothermal processes the 2d geometry of valley networks show drainage densities reaching 1 3 km 1 that indicate a strong 2d extension stage that usually requires a minimum of thousands of years as established from terrestrial examples however the 3d valley geometry shows a limited incision and a lack of concavity suggesting a limited development in time millions of years of evolution are unlikely many outlets connect to the heads of canyons of echus chasma that might involve sapping processes these canyons might have formed coevally with shallow valleys their difference in geometry is a consequence of the difference in lithology which induced a difference in the erosion capacity and an enhanced infiltration conducing to sapping valleys are submitted to modification by aeolian processes sometimes leading to the formation of inverted channels as observed more broadly through the region these landforms formed late in the early mars history and might be considered as examples of episodic fluvial events due to short term climate changes and or regional fluvial activity after the noachian

topography of valley networks on mars from mars express high resolution stereo camera digital elevation models 1 martian valley networks have been identified mainly in the noachian heavily cratered uplands the geometry of valley networks can be studied using mars orbiter laser altimeter mola altimetry which is sufficient to map large valleys without a detailed 3 d shape of valley networks imaging from the mars express high resolution stereo camera hrsc is used to generate digital elevation models dems with resolution 50 m and vertical accuracy 60 m we studied valleys near huygens crater and in the aeolis region both in the noachian bedrock and on the west echus plateau in hesperian bedrock hrsc dems in these areas show that 1 drainage density is 3 times higher than is observed in mola data 2 degree of ramification is 1 order more than with mola 3 transverse valley profiles show a v shape more accurately and a minimum depth of 20 m and 4 higher drainage density shows greater headward extension that is not correlated to greater valley depth the deepest valleys 400 m are found in the huygens region where the density in the dem is 0 1 km 1 compared to shallow valleys 100 m of the echus region where the density is higher 0 3 km 1 these regional differences are due to spatially variable preservation and bedrock lithology longitudinal profiles suggest variations in duration of activity profile concavity is only developed in some noachian terrains valleys visible in hrsc images correspond to topographic features in dems showing the same geometry as terrestrial valleys thought to be formed by overland flows and seepage

growth fault bend folding at southeast lost hills san joaquin valley california synsedimentary deformation has created complex structural and stratigraphic relationships along the west side of the san joaquin valley california this case study of lost hills anticline documents how a simple structural process fault bend folding results in complex growth stratigraphy lost hills anticline is a fault bend fold caused by a step in the lost hills thrust the thrust steps up to the northeast at 27 from a detachment at the base of the tertiary to an upper detachment in the reef ridge formation the lower and upper detachments are at 20 000 ft 6 km and 13 000 ft 4 km displacement on the lower detachment is approximately 4 mi 6 5 km folding consumes 1 2 mi 2 km and the remaining 2 8 mi 4 5 km continues northeast beneath the san joaquin va ley forward and back limb dips of 42 and 27 respectively are consistent with fault bend fold theory pliocene pleistocene sediments onlap a time transgressive unconformity on the northeast front limb but have uniform dip and thickness on the southwest back limb this characteristic growth fault bend fold geometry indicates basinal sediments rolled through an axial surface onto the back limb whereas contemporaneous sediments deposited above the front limb are undeformed basinal sediments onlapping the fold crest indicates fault slip is greater than ramp length onlapping growth sediments indicate folding began during deposition of the etchegoin formation 8 ma and continued to the late pleistocene or holocene corresponding to an average displacement rate on the lost hills thrust of 2 700 ft m y 820 m m y continuous burial of the fold during growth caused each material e physical point in the fold to be at its maximum depth of burial contours of equal density and seismic velocity are relatively flat so that the anticline causes little or no gravity anomaly and less than expected pullup in seismic time sections the geometry of growth sediments imaged on seismic lines indicates lost hills and adjacent anticlines grew by uniform displacement to the northeast with no significant rotation oblique convergence between the pacific and north american plates is manifested as synchronous but spatially separate transcurrent and compressive displacements thus lost hills anticline and perhaps other folds in the area are more appropriately described as compressive folds in a transpressive region than as transpressive folds duplicated lower tertiary strata beneath the lost hills kettleman hills trend are potential targets for petroleum exploration

light toned layered deposits in juventae chasma mars abstract we examine hypotheses for the formation of light toned layered deposits in juventae chasma using a combination of data from mars global surveyor s mars orbiter camera moc mars orbiter laser altimeter mola and thermal emission spectrometer tes as well as mars odyssey s thermal emission imaging system themis we divide juventae chasma into geomorphic units of i chasm wall rock ii heavily cratered hummocky terrain iii a mobile and largely crater free sand sheet on the chasm floor iv light toned layered outcrop llo material and v chaotic terrain using surface temperatures derived from themis infrared data and slopes from mola we derive maps of thermal inertia which are consistent with the geomorphic units that we identify llo thermal inertias range from 400 to 850 j m 2 k 1 s 1 2 light toned layered outcrops are distributed over a remarkably wide elevation range 5 8 km from the chasm floor to the adjacent plateau surface geomorphic features the absence of small craters and high thermal inertia show that the llos are composed of sedimentary rock that is eroding relatively rapidly in the present epoch we also present evidence for exhumation of llo material from the west wall of the chasm within chaotic and hummocky terrains and within a small depression in the adjacent plateau the data imply that at least some of the llo material was deposited long before the adjacent hesperian plateau basalts and that juventae chasma underwent and may still be undergoing enlargement along its west wall due to wall rock collapse chaotic terrain evolution and exposure and removal of llo material the new data allow us to reassess possible origins of the llos gypsum one of the minerals reported elsewhere as found in juventae chasma llo material forms only at low temperatures 60 c and thus excludes a volcanic origin instead the data are consistent with either multiple occurrences of lacustrine or airfall deposition over an extended period of time prior to emplacement of hesperian lava flows on the plateau above the chasm

testing evidence of recent hydration state change in sulfates on mars the east candor interior layered deposit ild has signatures of mono and polyhydrated sulfate in alternating layers that give insight into the processes which formed these layered deposits and on the environmental conditions acting on them since then we use orbital data to explore multiple hypotheses for how these deposits formed 1 sulfate bearing ilds experience hydration changes on seasonal to a few years timescales under current mars environmental conditions 2 the deposits experience hydration under recent mars conditions but require the wetter climate of high obliquity and 3 the kieserite could be an original or diagenetic part of a complex evaporite mineral assemblage modeled climatology shows recent mars environmental conditions might pass between multiple sulfate fields however comparison of observatoire pour la mineralogie l eau les glaces et l activite omega and compact reconnaissance imaging spectrometer crism observations of the same ild do not show changes in hydration over 2 mars years low temperatures might slow the kinetics of that transition it is likely that more clement conditions during periods of high obliquity are needed to overcome mineral metastability and hydrate kieserite bearing deposits we find the alternate model that the deposit is a cyclic evaporite sequence of mono and polyhydrated sulfates also plausible but with an unexplained dearth of fe sulfates

characterization of phyllosilicates observed in the central mawrth vallis region mars their potential formational processes and implications for past climate mawrth vallis contains one of the largest exposures of phyllosilicates on mars nontronite montmorillonite kaolinite and hydrated silica have been identified throughout the region using data from the compact reconnaissance imaging spectrometer for mars crism in addition saponite has been identified in one observation within a crater these individual minerals are identified and distinguished by features at 1 38 1 42 1 91 and 2 17 2 41 m there are two main phyllosilicate units in the mawrth vallis region the lowermost unit is nontronite bearing unconformably overlain by an al phyllosilicate unit containing montmorillonite plus hydrated silica with a thin layer of kaolinite plus hydrated silica at the top of the unit these two units are draped by a spectrally unremarkable capping unit smectites generally form in neutral to alkaline environments while kaolinite and hydrated silica typically form in slightly acidic conditions thus the observed phyllosilicates may reflect a change in aqueous chemistry spectra retrieved near the boundary between the nontronite and al phyllosilicate units exhibit a strong positive slope from 1 to 2 m likely from a ferrous component within the rock this ferrous component indicates either rapid deposition in an oxidizing environment or reducing conditions formation of each of the phyllosilicate minerals identified requires liquid water thus indicating a regional wet period in the noachian when these units formed the two main phyllosilicate units may be extensive layers of altered volcanic ash other potential formational processes include sediment deposition into a marine or lacustrine basin or pedogenesis

stratigraphy and erosional landforms of layered deposits in valles marineris mars the complex stratigraphy of layered deposits suggests a diversity of origins ages and post depositional modification histories the complexities within some layered deposits indicate changes in the dominant source materials in space and time the stratigraphy of layered deposits in the isolated martian chasmata hebes juventae and gangis is not well correlated this indicates that at least these chasmata had isolated depositional environments resulting in different stratigraphic sequences separated layered deposits in ophir candor and melas chasmata might have been a single continuous deposit in each chasma chaotic terrains are found in conjunction with layered deposits in juventae gangis and capri eos chasmata in these chasmata layered deposits unconformably overlie chaotic terrains chaotic terrain formation may have provided water to form paleolakes and lacustrine deposition of thick layered deposits may have occurred if the canyons were closed a very thick sequence of the layered deposits has been exposed by erosion a combination of gradual processes such as evaporation of ice and eolian and fluvial transport in addition to structural processes may be responsible for this erosion another alternative is that catastrophic water release under the layered deposits disrupted and initiated erosion of the layered deposits newly identified units of anomalous color are confined to the depressions or reentrants in western candor chasma the difference in color between these units and the surrounding terrain is most consistent with a somewhat greater content of bulk crystalline hematite in these anomalous units the presence of the candor units is a result of original and or secondary deposition which is different from the primary and dominant formation of the layered deposits

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

mars reconnaissance orbiter observations of light toned layered deposits and associated fluvial landforms on the plateaus adjacent to valles marineris abstract we have used data from the mars reconnaissance orbiter to study 30 80 m thick light toned layered deposits on the plateaus adjacent to valles marineris at five locations 1 south of ius chasma 2 south of western melas chasma 3 south of western candor chasma 4 west of juventae chasma and 5 west of ganges chasma the beds within these deposits have unique variations in brightness color mineralogy and erosional properties that are not typically observed in light toned layered deposits within valles marineris or many other equatorial areas on mars reflectance spectra indicate these deposits contain opaline silica and fe sulfates consistent with low temperature acidic aqueous alteration of basaltic materials we have found valley or channel systems associated with the layered deposits at all five locations and the volcanic plains adjacent to juventae ius and ganges exhibit inverted channels composed of light toned beds valleys channels and light toned layering along the walls of juventae and melas chasmata are most likely coeval to the aqueous activity that affected the adjacent plateaus and indicate some hydrological activity occurred after formation of the chasmata although the source of water and sediment remains uncertain the strong correlation between fluvial landforms and light toned layered deposits argues for sustained precipitation surface runoff and fluvial deposition occurring during the hesperian on the plateaus adjacent to valles marineris and along portions of chasmata walls

acid fog deposition at kilauea volcano a possible mechanism for the formation of siliceous sulfate rock coatings on mars on the summit of kilauea volcano sulfur dioxide which is continuously emitted from halemaumau crater and rapidly sequestered into sulfuric acid rich aerosol entrained in the prevailing trade winds is subsequently precipitated as acid fog immediately downwind from kilauea caldera in the kau desert the characteristic ph of surface tephra deposits is 4 0 in sand wash a region of nearly continuous acidic aerosol fallout immediately southwest of the caldera vertical exposures of unconsolidated tephras of the keanakakoi ash found within fissures and small dry gullies are coated with thin rock coatings of amorphous silica and jarosite these rock coatings are formed via an evaporative mechanism whereby acidic pore fluids circulating in the upper few meters within the highly porous tephra are wicked toward the walls of the gullies geochemical modeling of the rock coating formation process implies that the sulfate formation via evaporation occurs subsequent to minimal interaction of acidic pore fluids with the basaltic tephra this also suggests that the cycle from acid fog fallout to precipitation of the siliceous sulfate rock coatings must occur quite rapidly acid fog deposition of sulfate and silica at kilauea may provide one mechanism for the origin of jarosite bearing outcrops on mars

young volcanic deposits in the valles marineris mars abstract a study of the interior deposits of the central valles marineris has led to the discovery of a sequence of deposits that cover the chasma floors and range in thickness from that of thin dust to several kilometers the emplacement of the deposits was the last major event in the history of the valles marineris following deposition of older layered interior beds warping faulting erosion and landslide emplacement the young deposits are of three major types 1 dark patches typically occurring along faults 2 light colored deposits locally associated with craters and 3 rugged mottled deposits with in places light colored lobate fronts these young materials may be of volcanic origin as suggested by the low albedo and spectrally gray colors of some their association with faults and possible volcanic craters and calderas and their embayment relations and lobate margins no other mechanism explains all the observed features and relations as well as volcanism if these deposits are volcanic implications are that 1 volcanism was associated with rifting in the valles marineris 2 the volcanism was explosive in places and 3 the volcanism may be as young as the late tharsis volcanism and locally may well be recent

origin and evolution of the layered deposits in the valles marineris mars abstract thick sequences of layered deposits are found in the martian valles marineris they exhibit fine nearly horizontal layering and are present as isolated plateaus of what may have once been more extensive deposits individual sequences of layered deposits are as thick as 5 km the greatest total thicknesses of deposits are found in candor ophir and melas chasmata individual layer thicknesses range from about 70 to 300 m some tilting of sequences is observed but at the best image resolutions no angular unconformities are detectable in the layers the sequences of events in the canyons as deduced from morphologic and stratigraphic evidence was 1 graben formation in response to the tharsis uplift 2 canyon wall retreat and canyon enlargement roughly contemporaneous with formation of the layered deposits 3 deep erosion of the layered deposits 4 landsliding of the canyon walls and 5 eolian erosion of the layered deposits perhaps continuing up to the present we consider four hypotheses for the origin of the layered deposits they are eolian deposits they are remnants of the material that makes up the canyon walls they are deposits of explosive volcanic eruptions or they were deposited in standing bodies of water the rhythmic nature of the layers and their lateral continuity horizontality great thickness and stratigraphic relationships with other units in the canyons all appear most consistent with deposition in an aqueous environment if standing bodies of water existed in the valles marineris they were almost certainly ice covered there are three ways in which sediment could have entered an ice covered lake down through the ice cover up from the lake bottom or in from the lake margins layers of sediment could have been transported downward through an ice cover by foundering or rayleigh taylor instabilities but it is not clear whether there was a viable mechanism for repeatedly accumulating thick sediment layers on top of the ice cover subaqueous volcanic eruption on the lake bottom does not suffer from many of the morphologic arguments that make origin by subaerial volcanism seem improbable while this mechanism is attractive there are no eruptive centers observed and there is no other direct evidence to support it because canyon enlargement took place at roughly the same time as layer deposition debris from the canyon walls is an obvious and likely source for some of the material in the layered deposits however the volume of material removed from the canyon walls may be insufficient to account for all of the presently observed material we conclude that there are several geologically feasible but as yet unproven mechanisms that could have led to formation of thick deposits in ice covered paleolakes in the valles marineris present data are insufficient to choose conclusively among the various possibilities several types of data from the mars observer mission will be useful in further characterizing the deposits and clarifying the process of their origin the deposits should be considered important targets for a future mars sample return mission

wind induced oscillator dynamics in the black sea revealed by lagrangian drifters 1 lagrangian drifter observations of the black sea circulation between 2002 and 2003 show six transitions between two meta stable states representing single gyre structures centered in either the western or eastern sub basin of the black sea respectively the major mechanisms driving such an oscillator dynamics are ekman pumping for the eastern sub basin and most likely a resonance excitation for the western sub basin the sea strongly amplifies the wind responses of 120 day periodicity data analysis demonstrates that two gyre structure knipovich spectacles was a transient between the states residence time for the sea to occupy either state is mainly determined by the instability of the gyres wind variability and probably variations in the pycnocline this behavior is a manifestation of a bimodal dynamical regime which affects the long term climatic large scale transport and mixing of bio geochemical substances

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

validation of ocean tide models around antarctica using onshore gps and gravity data 1 ocean tide models around antarctica are presently only sparsely tested against independent data ocean tide modeling errors along with subsequent ocean tide loading otl displacement modeling errors alias into altimetry and time variable gravity e g gravity recovery and climate experiment grace time series for example to validate various ocean tide models around antarctica gps data from 15 sites have been used to derive three dimensional displacement estimates at eight diurnal and semidiurnal tidal frequencies using hundreds of days of gps data harmonic parameters were estimated on a daily basis then combined these were then compared with otl displacement estimates derived from global and regional ocean tide models in east antarctica where the tides are well defined submillimeter differences are demonstrated in each coordinate component with the lunar n2 and q1 constituents in closest agreement as found in other studies k1 and especially k2 agree less well the spatial variation in the misfits for these two constituents indicates a site dependency with the k2 errors also suggesting an interaction with satellite dependent effects in west antarctica where sites are nearer the largest ice shelves agreement with the older models csr3 and tpxo 2 and nao 99b is poor for all constituents modeled tidal gravity variations were also compared with gravity measurements at the south pole overall the gps and gravity data agree best with newer tide models namely tpxo 6 cada00 10 fes99 and cats02 01 however validation data are lacking at the southern extents of the large ice shelves and hence some uncertainty still exists in all ocean tide models in these regions