an outline of the plate tectonics of china china is principally a part of the eurasian plate but the margins of the indian and philippine sea plates are involved in the himalayas and in the coastal range of taiwan respectively within the eurasian plate the cathaysian paleoplate is separated from the angaraian paleoplate by the junggar hegen suture which contains paleozoic ophiolites and rare blueschists the three microplates of the cathaysian paleoplate consist of precambrian cratons and or phanerozoic accretionary fold belts these coalesced precambrian cratons record at least six stages of intense orogeny before cratonization the paleozoic to cenozoic accretionary fold belts of china can be correlated with similar events now found in west pacific andean and atlantic type active continental margins ophiolites occupying many of these tectonic zones provide evidence for the age and igneous history of oceanic crust formed during the paleozoic to cenozoic the presence of blueschist in some of these chinese sutures reveals evidence of large scale subduction and tectonic exhumation during consolidation of the eurasian plate cenozoic collision of the eurasian and indian plates produced deformation and uplift of the himalayas strongly influencing the tectonics of western china in contrast mesozoic tertiary evolution of eastern china is typical basin range geology similar to that of the western united states which included development of deep sedimentary basins along with calc alkaline plutonic and volcanic activity associated with crustal thinning and high heat flow the complicated tectonic evolution of china is greatly illuminated by the presence of ophiolites and blueschists in proterozoic to tertiary convergent boundaries these petrotectonic assemblages provide evidence of an extremely mobile history of plate movement in china

detecting volcanism on titan and venus with microwave radiometry the detection by spaceborne instrumentation of infrared thermal emission from volcanic eruptions is well established on earth but is challenged on venus and titan by their optically thick atmospheres microwave radiometry in principle offers the ability to detect emission from surface thermal anomalies on these worlds due to greater atmospheric transparency microwaves also offer the prospect of sensing the shallow subsurface and thus may detect warmth from lava flows for longer than surface infrared emission however satellite microwave instruments typically have low spatial resolution 10s of km so volcanic heat is diluted in the wide instrument footprint we examine the prospects for the detection of volcanic deposits by microwave given likely planetary eruption rates and lava flow deposit geometries using mt etna as a template nondetection of prominent hotspots in cassini data may imply that the resurfacing rate is lower than 2 km3 yr five times smaller than the expression of an earth like fraction of geothermal heat flow as latent heat in extrusive volcanism

dune forming winds on titan and the influence of topography abstract numerous extended dunes on saturn s moon titan detected by the cassini radar constrain the long term pattern of surface winds we analyse the statistics of surface wind speed and direction and their spatial and temporal variability predicted by a general circulation model gcm in order to constrain surface wind predictions of this gcm by dune observations the model shows that modern winds are sufficient for saltation and dune formation at low latitudes in agreement with the presence of dunes there the best condition for the dune forming wind occurs with a threshold friction speed of 0 02 m s 1 or slightly less the equatorial region is conducive to longitudinal dunes because of a combined effect of a high sand drift potential and obtuse bimodal wind pattern oblique to the equator caused by the seasonal reversal of the hadley circulation the cross equatorial wind is steady and is characterised by a high weibull shape parameter k 4 the wind pattern at higher latitudes is more complex and gusty and neither longitudinal nor transversal dunes would be able to form putative large scale topography is found to have a profound influence on the near surface wind pattern generally mountains cause a convergence and speeding up on the flank while basins weaken the wind and cause a divergent flow longitudinal dunes can be deflected on the foot of mountains by up to 90 if xanadu is a hypothetical large mountain a wind pattern converging in xanadu that entirely disagrees with the dune observations is predicted if instead xanadu is a large basin the wind arcs clockwise north of xanadu and anti clockwise west and southwest of xanadu in agreement with the dune orientations in the vicinity of xanadu the albedo pattern has comparatively little influence on the wind field isolated mountain chains cause only local scale change in the wind pattern however the persistent surface easterlies in belet which are in conflict with the dune orientations do not disappear by any combination of large scale topography

anomalous radar backscatter from titan s surface abstract since cassini arrived at saturn in 2004 its moon titan has been thoroughly mapped by the radar instrument at 2 cm wavelength in both active and passive modes some regions on titan including xanadu and various bright hummocky bright terrains contain surfaces that are among the most radar bright encountered in the solar system this high brightness has been generally attributed to volume scattering processes in the inhomogeneous low loss medium expected for a cold icy satellite surface we can test this assumption now that the emissivity has been obtained from the concurrent radiometric measurements for nearly all the surface with unprecedented accuracy janssen et al and the cassini radar team 2009 icarus 200 222 239 kirchhoff s law of thermal radiation relates the radar and radiometric properties in a way that has never been fully exploited in this paper we examine here how this law may be applied in this case to better understand the nature of titan s radar bright regions we develop a quantitative model that when compared to the observational data allows us to conclude that either the reflective characteristics of the putative volume scattering subsurface must be highly constrained or more likely organized structure on or in the surface is present that enhances the backscatter

titan radar mapper observations from cassini s t3 fly by cassini s titan radar mapper imaged the surface of saturn s moon titan on its february 2005 fly by denoted t3 collecting high resolution synthetic aperture radar and larger scale radiometry and scatterometry data these data provide the first definitive identification of impact craters on the surface of titan networks of fluvial channels and surficial dark streaks that may be longitudinal dunes here we describe this great diversity of landforms we conclude that much of the surface thus far imaged by radar of the haze shrouded titan is very young with persistent geologic activity

transformation of jarosite to hematite in simulated martian brines the presence of jarosite a hydrous iron sulfate at meridiani planum supports the past existence of water on mars surface thermodynamic calculations suggest that jarosite should transform to ferric oxyhydroxides in aqueous media here we show that jarosite can transform directly to hematite the iron oxide identified at meridiani planum in simulated martian brines our results are consistent with a short aqueous history but also indicate that jarosite can persist in highly saline martian brines the formation of goethite a common iron oxyhydroxide on earth is prevented by the low water activity and or high phosphate concentration of martian brines

mantle dynamics uplift of the tibetan plateau and the indian monsoon convective removal of lower lithosphere beneath the tibetan plateau can account for a rapid increase in the mean elevation of the tibetan plateau of 1000 m or more in a few million years such uplift seems to be required by abrupt tectonic and environmental changes in asia and the indian ocean in late cenozoic time the composition of basaltic volcanism in northern tibet which apparently began at about 13 ma implies melting of lithosphere not asthenosphere the most plausible mechanism for rapid heat transfer to the midlithosphere is by convective removal of deeper lithosphere and its replacement by hotter asthenosphere the initiation of normal faulting in tibet at about 8 3 ma suggests that the plateau underwent an appreciable increase in elevation at that time an increase due solely to the isostatic response to crustal thickening caused by india s penetration into eurasia should have been slow and could not have triggered normal faulting another process such as removal of relatively cold dense lower lithosphere must have caused a supplemental uplift of the surface folding and faulting of the indo australian plate south of india the most prominent oceanic intraplate deformation on earth began between about 7 5 and 8 ma and indicates an increased north south compressional stress within the indo australian plate a tibetan uplift of only 1000 m if the result of removal of lower lithosphere should have increased the compressional stress that the plateau applies to india and that resists india s northward movement from an amount too small to fold oceanic lithosphere to one sufficient to do so the climate of the equatorial indian ocean and southern asia changed at about 6 9 ma monsoonal winds apparently strengthened northern pakistan became more arid but weathering of rock in the eastern himalaya apparently increased because of its high altitude and lateral extent the tibetan plateau provides a heat source at midlatitudes that should oppose classical symmetric hadley circulation between the equator and temperate latitudes and that should help to drive an essentially opposite circulation characteristic of summer monsoons for the simple case of axisymmetric heating no dependence on longitude of an atmosphere without dissipation theoretical analyses by hou lindzen and plumb show that an axisymmetric heat source displaced from the equator can drive a much stronger meridianal monsoonlike circulation than such a source centered on the equator but only if heating exceeds a threshold whose level increases with the latitude of the heat source because heating of the atmosphere over tibet should increase monotonically with elevation of the plateau a modest uplift 1000 2500 m of tibet already of substantial extent and height might have been sufficient to exceed a threshold necessary for a strong monsoon the virtual simultaneity of these phenomena suggests that uplift was rapid approximately 1000 m to 2500 m in a few million years moreover nearly simultaneously with the late miocene strengthening of the monsoon the calcite compensation depth in the oceans dropped plants using the relatively efficient c4 pathway for photosynthesis evolved rapidly and atmospheric co2 seems to have decreased suggesting causal relationships and positive feedbacks among these phenomena both a supplemental uplift of the himalaya the southern edge of tibet and a strengthened monsoon may have accelerated erosion and weathering of silicate rock in the himalaya that in turn enhanced extraction of co2 from the atmosphere thus these correlations offer some support for links between plateau uplift a downdrawing of co2 from the atmosphere and global climate change as proposed by raymo ruddiman and froehlich mantle dynamics beneath mountain belts not only may profoundly affect tectonic processes near and far from the belts but might also play an important role in altering regional and global climates

titan s surface from reconciled cassini microwave reflectivity and emissivity observations abstract the surface of titan saturn s largest moon appears to consist of solid hydrocarbons or co2 with considerable small scale structure according to a new electromagnetic scattering model that uses both cassini radar reflectivity and emissivity measurements our model resolves a well known ambiguity in active and passive observations of surfaces namely that the dielectric constant retrieved from radiometric data is usually less than that obtained from radar backscatter analysis we present here parameters of titan derived from radar and radiometric responses using a single set of surface physical descriptors the observed dielectric constant ranges from 1 75 2 5 consistent with the solids above but also with unconsolidated water or water ammonia ice inferred rms slopes of the surface range from 10 16 at cassini s 2 2 cm with radar albedos of about 30 emissivities of the surface are quite high on the order of 90 we find that the majority of the backscattered radar energy results from volume rather than surface scattering processes thus large scale variations in radar brightness are mainly diagnostic of composition and structure within titan s near subsurface the high level of volume scatter about 15 of incident energy and consequent high radar albedo suggest significant wavelength scale structure and multiple scatter within the medium this is most consistent with a surface composed either of ubiquitous mm size bubbles within the ice analogous to a vesicular cryolava or structures similar to ice pipes and lenses found in terrestrial ice sheets the cryovolcanic hypothesis suggests planet wide resurfacing by active volcanism to explain the large scale uniformity of observed backscatter if the lens pipe mechanism pertains it can imply percolation of precipitating liquid or surface melt through the titan firn

structural petrological and thermal evolution of a tertiary ductile strike slip shear zone diancang shan yunnan the diancang shan a horst massif within the red river fault zone in yunnan people s republic of china preserves a structural petrological and thermal record of two distinct phases of tectonic activity a left lateral ductile shear that terminated between 20 and 17 ma and a ductile to brittle phase of normal faulting which began at 4 7 ma and remains active mylonitic rocks in the core of the range display an early steep high temperature ht schistosity and a horizontal stretching lineation that are both parallel to the trend of the belt kinematic indicators indicate that shear was left lateral the complex shape of the ht schistosity at the southern termination of the massif likely results from a large scale oblique left lateral c shear plane that dismembered the shear zone and separated the ailao shan and the diancang shan as left lateral deformation terminated thermochronological and thermobarometric results suggest that the gneisses were partially unroofed during this event along the eastern edge of the diancang shan the ht fabrics were overprinted by low temperature structures during activation of east dipping normal faults cooling associated with this normal right lateral faulting along the diancang shan and perhaps activation of the right lateral normal movement on the range front fault farther south along the ailao shan began at 4 7 0 1 ma these results tend to support the view that extrusion of indochina occurred along the left lateral red river shear zone between 35 and 19 17 ma initiation of right lateral normal slip during the late miocene may relate to eastward extensional collapse of the thickened tibetan crust or more probably to initiation of the second phase of extrusion

cenozoic uplift and deformation of the tibetan plateau the geomorphological evidence an erosion surface interpreted as a pediplain is traced across the tibetan plateau as a result of faulting and warping its elevation now varies from approximately 4500 6000m it was cut across folded and thrust eocene strata and mid miocene granites but was dislocated by major faults before the pliocene its age is thought to be mid to late miocene crustal shortening after pediplanation is small if the crust beneath the plateau was thickened by deformation during crustal shortening the thickening must mainly have occurred before the pediplanation

on titan s xanadu region abstract a large circular marking 1800 km across is seen in near infrared images of titan the feature is centered at 10 s 120 w on titan encompasses much of titan s western xanadu region and has an off center quasi circular inner margin about 700 km across with lobate outer margins extending 200 500 km from the inner margin on the feature s southern flank is tui regio an area that has very high reflectivity at 5 m and is hypothesized to exhibit geologically recent cryovolcanic flows barnes j w et al 2006 geophys res lett 33 similar to flows seen in hotei regio a cryovolcanic area whose morphology may be controlled by pre existing crustal fractures resulting from an ancient impact soderblom l a et al 2009 icarus 204 the spectral reflectivity of the large circular feature is quite different than that of its surroundings making it compositionally distinct and radar measurements of its topography brightness temperature and volume scattering also suggest that the feature is quite distinct from its surroundings these and several other lines of evidence in addition to the feature s morphology suggest that it may occupy the site of an ancient impact

new constraints on the tectonic evolution of the eastern indian ocean abstract from marine magnetic anomaly studies a fossil spreading ridge is identified beneath the nicobar fan in the northwestern wharton basin several north south trending transform faults offset this ridge left laterally east of the 86 e transform fault our findings show that this ridge which was part of the plate boundary between the indian and australian plates ceased its spreading shortly after formation of magnetic anomaly 20 45 6m y b p since the breakup of australia and antarctica probably occurred sometime between 110 and 90 m y b p we suggest that the indian australian and antarctic plates were moving relative to one another from about 90 to 45 m y b p a triple junction would have existed in the southeastern indian ocean during that period of time at anomaly 19 time 45m y b p the junction became inactive and australia and india became a single plate the northwest southeast trending southeast indian ridge was formed by connecting the india antarctica spreading center with the australia antarctica spreading center its activity has continued to the present time

formation of jarosite bearing deposits through aqueous oxidation of pyrite at meridiani planum mars 1 the discovery of sulfate rich layered deposits with hematite spherules at the landing site of the opportunity rover is consistent with mineral deposition in an aqueous environment we evaluate conditions responsible for the formation of a jarosite goethite gypsum assemblage with speciation calculations the results show that the assemblage could have precipitated from acidic solutions formed through near surface aqueous oxidation of pyrite our hypothesis is that regional heating in the meridiani planum caused a release of sulfide rich hydrothermal waters leading to formation of pyrite rich regional deposits in a depression aqueous oxidation of these deposits by atmospheric o2 created an acidic environment that allowed formation of sulfates and goethite partial neutralization of the solution caused further goethite precipitation and conversion of jarosite to goethite leading to formation of goethite concretions subsequent dehydration of goethite to coarse grained hematite would also have been facilitated by regional heating

mossbauer mineralogy of rock soil and dust at gusev crater mars spirit s journey through weakly altered olivine basalt on the plains and pervasively altered basalt in the columbia hills 1 the mossbauer spectrometer on spirit measured the oxidation state of fe identified fe bearing phases and measured relative abundances of fe among those phases for surface materials on the plains and in the columbia hills of gusev crater eight fe bearing phases were identified olivine pyroxene ilmenite magnetite nanophase ferric oxide npox hematite goethite and a fe3 sulfate adirondack basaltic rocks on the plains are nearly unaltered fe3 fet px and minor npox and magnetite columbia hills basaltic rocks are nearly unaltered peace and backstay moderately altered woolypatch wishstone and keystone and pervasively altered e g clovis uchben watchtower keel and paros with fe3 fet 0 6 0 9 fe from pyroxene is greater than fe from olivine ol sometimes absent and fe2 from ol px is 40 49 and 9 24 for moderately and pervasively altered materials respectively ilmenite fe from ilm 3 6 is present in backstay wishstone keystone and related rocks along with magnetite fe from mt 10 15 remaining fe is present as npox hematite and goethite in variable proportions clovis has the highest goethite content fe from gt 40 goethite feooh is mineralogical evidence for aqueous processes because it has structural hydroxide and is formed under aqueous conditions relatively unaltered basaltic soils fe3 fet 0 3 occur throughout gusev crater 60 80 fe from ol px 10 30 from npox and 10 from mt pasorobles soil in the columbia hills has a unique occurrence of high concentrations of fe3 sulfate 65 of fe magnetite is identified as a strongly magnetic phase in martian soil and dust

how flat is tibet high resolution digital topography three arc second grid for most of tibet provides new information to characterize the relief of the highest and largest plateau on earth the arid to semiarid central and northern part of the plateau interior has low relief average slopes of over 250 m windows and a mean elevation of 5023 m above sea level at moderate wavelengths of m relief is or less for most of tibet as opposed to the much higher relief of up to 6 km on the plateau edges where glacial and fluvial dissection is greater because of higher levels of precipitation the only faults manifesting significant topographic relief are the relatively small scale generally north trending graben systems primarily in southern tibet and several large scale fault systems near the edges of tibet the flatness of tibet implies that 1 there has been little deformation especially shortening of the uppermost crust north of the graben systems during the late cenozoic and 2 shallow crustal isostatic compensation has been acting to level the surface of the plateau

iron mineralogy and aqueous alteration from husband hill through home plate at gusev crater mars results from the mossbauer instrument on the spirit mars exploration rover 1 spirit s mossbauer mb instrument determined the fe mineralogy and oxidation state of 71 rocks and 43 soils during its exploration of the gusev plains and the columbia hills west spur husband hill haskin ridge northern inner basin and home plate on mars the plains are predominantly float rocks and soil derived from olivine basalts outcrops at west spur and on husband hill have experienced pervasive aqueous alteration as indicated by the presence of goethite olivine rich outcrops in a possible mafic ultramafic horizon are present on haskin ridge relatively unaltered basalt and olivine basalt float rocks occur at isolated locations throughout the columbia hills basalt and olivine basalt outcrops are found at and near home plate a putative hydrovolcanic structure at least three pyroxene compositions are indicated by mb data mb spectra of outcrops barnhill and torquas resemble palagonitic material and thus possible supergene aqueous alteration deposits of fe3 sulfate soil located at paso robles arad and tyrone are likely products of acid sulfate fumarolic and or hydrothermal activity possibly in connection with home plate volcanism hematite rich outcrops between home plate and tyrone e g montalva may also be products of this aqueous activity low water to rock ratios isochemical alteration are implied during palagonite goethite and hematite formation because bulk chemical compositions are basaltic so3 free basis high water to rock ratios leaching under acid sulfate conditions are implied for the high sio2 rock and soil in eastern valley and the float rock fuzzysmith which has possible pyrite marcasite as a hydrothermal alteration product

fe mg smectite formation under acidic conditions on early mars abstract phyllosilicates of the smectite group detected in noachian and early hesperian terrains on mars have been hypothesized to form under neutral to alkaline conditions these ph conditions would also be favorable for formation of widespread carbonate deposits which have not been detected on mars we propose that smectite deposits on mars formed under moderately acidic conditions inhibiting carbonate formation we report here the first synthesis of fe mg smectite in an acidic hydrothermal system 200 c ph rt 4 ph measured at room temperature buffered with acetic acid from mars analogue glass rich basalt simulant with and without aqueous mg or fe ii addition under n 2 purged anoxic and ambient oxic redox conditions synthesized fe mg smectite was examined by x ray diffraction mossbauer spectroscopy visible and near infrared reflectance spectroscopy scanning electron microscopy and electron microprobe to characterize mineralogy morphology and chemical composition alteration of the glass phase of basalt simulant resulted in formation of the fe mg smectite mineral saponite with some mineralogical and chemical properties similar to the properties reported for fe mg smectite on mars our experiments are evidence that neutral to alkaline conditions on early mars are not necessary for fe mg smectite formation as previously inferred phyllosilicate minerals could instead have formed under mildly acidic ph conditions volcanic so 2 emanation and sulfuric acid formation is proposed as the major source of acidity for the alteration of basaltic materials and subsequent formation of fe mg smectite

material transport map of titan the fate of dunes abstract using sar data from cassini s radar instrument we examined the orientations of three terrain units on titan bright lineated plains streak like plains and linear dunes from the overall integrated pattern of their orientation we were able to determine titan s global material transport vectors the analysis indicates that in both the northern and southern hemispheres materials from 0 to 35 deg latitude are transported poleward to a belt centred at roughly 35 deg materials from 60 to 35 deg latitude are transported equatorward to the belt at roughly 35 deg comparison with the global topographical gradient lorenz r d et al 2013 icarus 225 367 377 suggests that fluvial transport is not the dominant process for material transport on titan or that it is at least overprinted with another transport mechanism our results are consistent with aeolian transport being the dominant mechanism in the equatorial and mid latitude zones the zone at 35 deg is thus the ultimate sink for materials from the equator to low polar latitudes materials making up the equatorial dunes will be transported to the latitude 35 deg belts only plains units are observed at latitudes of 35 deg dunes and materials with the spectral characteristics of dunes are not observed at these latitudes this observation suggests that either dune materials are converted or modified into plains units or that the margins of dunes are transport limited

synthesis of akaganeite in the presence of sulfate implications for akaganeite formation in yellowknife bay gale crater mars abstract akaganeite a cl bearing fe iii hydr oxide has been recently discovered in yellowknife bay in gale crater on mars by the mars science laboratory msl curiosity rover akaganeite was associated with sulfate and sulfide minerals at yellowknife bay indicating that sulfate ions could be present in solution during akaganeite formation the mechanism and conditions of akaganeite formation in the yellowknife bay mudstone are unknown we investigated formation of akaganeite through hydrolysis of ferric chloride solution in the presence of 0 0 01 0 05 0 1 and 0 2 m sulfate and at initial ph of 1 5 2 and 4 at 90 c mineralogy of the precipitated fe iii phases was characterized by x ray diffraction and infrared spectroscopy the precipitates were also acid digested to determine total sulfate and chloride contents akaganeite and natrojarosite formed at initial solution ph of 1 5 akaganeite goethite and natrojarosite precipitated in initial ph 2 solutions and goethite hematite and 2 line ferrihydrite precipitated at initial solution ph of 4 sulfate addition did not inhibit akaganeite formation increasing initial solution sulfate concentrations resulted in increasing sulfate to chloride ratio in the precipitated akaganeite infrared spectroscopy revealed akaganeite bands at 2 m h 2 o combination band and at 2 46 m oh combination band the h 2 o combination band position linearly correlated with total chloride content in akaganeite overall laboratory studies demonstrated formation of akaganeite at initial sulfate concentration 0 2 m sulfate to chloride molar ratio 0 3 and ph 2 implying that those conditions might prevail perhaps as micro environments during akaganeite formation in yellowknife bay mudstone the occurrence of fe ii sulfides pyrite and pyrrhotite in yellowknife bay mudstone is a potential acidity source dissolution of sulfide minerals might occur under localized oxidizing water limiting cl rich conditions creating favorable environments for akaganeite formation

india eurasia collision chronology has implications for crustal shortening and driving mechanism of plates the motion of the indian plate is determined in an absolute frame of reference and compared with the position of the southern margin of eurasia deduced from palaeomagnetic data in tibet the 2 600 900 km of continental crust shortening observed is shown to have occurred in three different episodes subduction of continental crust intracontinental thrusting and internal deformation and lateral extrusion the detailed chronology of the collision and plate reorganizations in the indian and pacific oceans supports the hypothesis that slab pull is a dominant driving mechanism of plate tectonics

mountains on titan modeling and observations 1 we have developed a thermal model of titan s interior to study changes in volume during partial freezing or melting of a subsurface ocean due to heat flux variations from the interior we find that the long term cooling of titan can cause global volume contraction v v 0 01 we then simulate two dimensional contractional deformation of titan s icy lithosphere finding that contractional deformation can produce tectonic activity and fold formation folds could potentially achieve a topographic height of several kilometers for high local strain 0 16 and for high temperature gradients in the ice i shell order of 10 k km 1 corresponding to an ancient high heat flux from the interior order of 0 02 0 06 w m 2 examination of synthetic aperture radar sar imagery obtained by cassini radar shows possible evidence of contractional tectonism in the equatorial regions of titan although the moderate resolution of the cassini sar imagery does not permit an unambiguous geological interpretation

mesozoic cenozoic rift drift sequence of asian fragments from gondwanaland abstract the university of cambridge atlas map plotting computer program has been used to plot a reconstruction of the dispersal of continental blocks from eastern gondwanaland from the late jurassic 160 ma until the late miocene 10 ma the geological basis for the reconstruction rests on the concept of south tibet burma western thailand malaya and sumatra having been part of the eastern gondwana continent during the late palaeozoic and early mesozoic the reconstruction is also based on the view that these asian continental blocks were rifted from eastern gondwanaland in the late jurassic this rifting episode gave rise to the continental margin of central new guinea and northern australia it was associated with the sea floor spreading anomalies preserved in the floor of the northeastern indian ocean the model considers the indication of crustal uplift in the middle jurassic followed by profound subsidence in the cretaceous and palaeogene exposed in the islands of the outer banda arc from seram to timor and the similar jurassic cretaceous facies in eastern sulawesi implies that these areas formed part of this rifted northern margin of australia in the jurassic subsequent tectonic collision and associated major strike slip movements have deformed and disrupted these rock sequences during the cainozoic the date of the rifting that removed south tibet burma western thailand and malaya from gondwanaland is controversial the indications in favour of the rifting episode having occurred in the jurassic rather than in the permo triassic are stratigraphie structural observations on the northwestern australian shelf in the banda arc and in central new guinea the identification of the continental blocks removed by this rifting is based partly on stratigraphie correlation with the banda arc and new guinea and partly on indications that the age of collision of tibet burma western thailand and malaya with asia was a late cretaceous event and not triassic jurassic as is generally held there are very few reliable land based palaeomagnetic measurements to constrain the movements of these dispersed continental fragments from gondwanaland the computer generated map reconstructions put forward here fit the available indian ocean sea floor spreading data although they are not unique solutions much of the critical ocean floor data associated with the rifting and dispersal of these continental fragments has been destroyed in the tectonic collision processes that occurred at the asian continental margin

titan and other icy satellites dielectric properties of constituent materials and implications for radar sounding abstract a number of scientific problems concerning titan and the other icy satellites of the outer solar system could be addressed by the technique of radar sounding we consider the materials present on and within these bodies model their dielectric properties and evaluate the extent to which radar signals can penetrate through them the primary materials of interest are h2o ice h2 nh3 solution simple and polymeric organic solids and ch4 c2h6 n2 liquid plus its minor organic and inorganic solutes penetration through h2o ice is limited by multiple scattering and by the long wavelength wing of the submillimeter band deep penetration is possible at long wavelengths and strong reflections could result from pockets or layers of subsurface h2o nh3 solution the dielectric constant of a putative ch4 c2h6 n2 ocean on titan is 1 65 1 81 depending on ch4 content and optical depth 40 to 200 cm 2 for depths of 0 75 to 7 km we estimate that dissolved species especially ch3cn hcn and h2o can increase the absorption by at least a factor of 2 but the effects of these polar solutes are very difficult to predict without direct experimental investigation and could be much greater sediment is composed of simple solids 2 0 2 4 and organic hetero polymers 4 5 5 5 with negligible radar attenuation to investigate a specific case of interest we consider radar observations of titan using the sounding mode of the cassini radar experiment we use our models to calculate radar signal noise ratios for reflections from titan the surface of titan is modeled as consisting of h2o ice covered by a 100 m thick layer of organic sediments overlain in turn by an ocean of liquid ch4 c2h6 n2 only reflections from the surface of the ocean in this model would be observed at a radar wavelength of 2 2 cm but at 13 6 cm we compute signal noise exceeding 10 db from the ocean sediment and sediment ice interfaces hence such a sounding mode may offer prospects for investigating the geology of titan even if the surface of the satellite is covered locally or globally by a deep ocean

cassini radar views the surface of titan the cassini titan radar mapper imaged about 1 of titan s surface at a resolution of 0 5 kilometer and larger areas of the globe in lower resolution modes the images reveal a complex surface with areas of low relief and a variety of geologic features suggestive of dome like volcanic constructs flows and sinuous channels the surface appears to be young with few impact craters scattering and dielectric properties are consistent with porous ice or organics dark patches in the radar images show high brightness temperatures and high emissivity and are consistent with frozen hydrocarbons

corrosion of fe ni alloys by cl containing akaganeite beta feooh the antarctic meteorite case a suite of 12 iron and 8 stony meteorites from various environments and locations in antarctica was studied representing a range of compositions metallographic structures and degrees of weathering polished sections of meteoritic metal with adhering corrosion products were examined microscopically with the electron microprobe and sem and were used as samples for x ray diffraction examination the major corrosion products are cl containing akaganeite up to 5wtper thousand cl and goethite with minor amounts of lepidocrocite and maghemite cl is not native to the meteorites but owing to the electrochemical nature of the corrosion of fe ni alloys is attracted from the snow and ice or rocky soil environment that contains low amounts of cl akaganeite precipitates near the reaction front incorporating cl ions into ion exchange sites where they may be retained made available for further depassivating corrosive action or become flushed from the system with time and distance from the reaction surface akaganeite ages and transforms to mainly goethite and maghemite it is again argued that lawrencite fecl 2 is not a mineral in meteorites in the stormy antarctic wind blown terrestrial particles may become attached to the weathering products on the meteorite and in time themselves decompose delivering terrestrial ions to the meteorite corrosion system the ions may move a significant distance from the surface and in particular cl may be found along almost invisible cracks in the deep interior trace element work and age determinations 36 cl should take this problem into account

exploring morphology layering and formation history of linear terrestrial dunes from radar observations implications for titan abstract understanding the morphology and internal layering of large aeolian dune fields through radar observations can provide unique insights into the climatic and geophysical conditions that led to their formation in this study we perform a large scale characterization of the morphology and internal layering of linear dunes in hyper arid areas on earth through utilizing multiple complementary radar datasets sir c imaging srtm interferometry derived elevations and radar sounding or ground penetrating radar gpr linear dune fields in the egyptian desert are of special interest due to their significance as planetary analogs to dunes on mars and saturn s largest moon titan satellite radar imagery and elevation data of the region show significant variance in the geomorphology of different dune fields in egypt in addition gpr probing of the first few meters suggests different inner settings in the layering of dunes of different ages in eastern and western egypt reflecting different paleo climatic regimes that led to their formation furthermore our radiometric analysis suggests that dunes with different inner layering arrangement also exhibit different radar backscatter returns as a function of their heights for relatively younger dunes with a homogeneous inner structure like the ones in eastern egypt in the qattaniya dune field we observe that sigma0 does not change as a function of the dune height for relatively older dunes in western egypt like the great sand sea northern siwa and southern dune fields we observed a linear correlation between sigma0 and the dune height thus surface properties of dunes like morphology and backscatter variation with height are related to inner characteristics like arrangement of internal layering relative ages and can be used to infer their depositional history linear dunes discovered in the equatorial regions of titan by the cassini huygens mission are morphologically very similar to these linear dune fields in the egyptian sahara hence assessing the variability of morphology and radar backscatter properties of titan s dunes as a function of their heights can help constrain the ambiguities associated with their internal structure and formation history and provide insights into titan s paleo wind regimes

geomorphologic mapping of the menrva region of titan using cassini radar data abstract we made a detailed geomorphologic map of the menrva region of titan using cassini radar data as our map base using similar techniques and approaches that were applied to mapping magellan radar images of venus and earlier more generalized titan maps we were able to define and characterize 10 radar morphologic units along with inferred dunes and fluvial channels from the radar data structural features such as scarps ridges and lineaments were also identified using principles of superposition cross cutting and embayment relations we created a sequence of map units for this region we interpret menrva to be a 440 km wide degraded impact basin in agreement with earlier studies by elachi et al elachi c et al 2006 nature 441 709 713 and wood et al wood c a lorenz r kirk r lopes r mitchell k stofan e and the cassini radar team 2010 icarus 206 334 344 and identify it as the oldest feature in the map region exogenic processes including hydrocarbon fluid channelization forming the elivagar flumina channel network and dune fields resulting from aeolian activity are the current geologic processes dominating our map area and these processes have contributed to the erosion of the crater s ejecta field there is evidence of multiple episodes of channel formation erosion and burial by aeolian deposits as observed elsewhere on titan by e g barnes et al barnes j w et al 2005 icarus 195 400 414 channel outflow regions have morphologies suggestive of streams formed by flash floods and dune fields are small and restricted rather than forming large dune seas consistent with a desert like environment for this region with low supply of hydrocarbon particles also consistent with other studies by e g lorenz et al lorenz r d et al 2008a planet space sci 56 1132 1144 there is no evidence of cryovolcanism or non impact related tectonic activity in the menrva region although this region is too small to infer anything about the roles of these processes elsewhere on titan this work suggests detailed geomorphologic mapping can confidently be applied to cassini radar data and we suggest that more extensive mapping should be done using radar iss and vims data geographically distributed across titan to assess its usefulness for a future combined radar iss vims based global geologic map

cassini radar observations of enceladus tethys dione rhea iapetus hyperion and phoebe cassini 2 2 cm radar and radiometric observations of seven of saturn s icy satellites yield properties that apparently are dominated by subsurface volume scattering and are similar to those of the icy galilean satellites average radar albedos decrease in the order enceladus tethys hyperion rhea dione iapetus and phoebe this sequence most likely corresponds to increasing contamination of near surface water ice which is intrinsically very transparent at radio wavelengths plausible candidates for contaminants include ammonia silicates metallic oxides and polar organics ranging from nitriles like hcn to complex tholins there is correlation of our targets radar and optical albedos probably due to variations in the concentration of optically dark contaminants in near surface water ice and the resulting variable attenuation of the high order multiple scattering responsible for high radar albedos our highest radar albedos for enceladus and tethys probably require that at least the uppermost one to several decimeters of the surface be extremely clean water ice regolith that is structurally complex i e mature enough for there to be high order multiple scattering within it at the other extreme phoebe has an asteroidal radar reflectivity that may be due to a combination of single and volume scattering iapetus 2 2 cm radar albedo is dramatically higher on the optically bright trailing side than the optically dark leading side whereas 13 cm results reported by black et al black g j campbell d b carter l m ostro s j 2004 science 304 553 show hardly any hemispheric asymmetry and give a mean radar reflectivity several times lower than the reflectivity measured at 2 2 cm these iapetus results are understandable if ammonia is much less abundant on both sides within the upper one to several decimeters than at greater depths and if the leading side s optically dark contaminant is present to depths of at least one to several decimeters as argued by lanzerotti et al lanzerotti l j brown w l marcantonio k j johnson r e 1984 nature 312 139 140 a combination of ion erosion and micrometeoroid gardening may have depleted ammonia from the surfaces of saturn s icy satellites given the hypersensitivity of water ice s absorption length to ammonia concentration an increase in ammonia with depth could allow efficient 2 2 cm scattering from within the top one to several decimeters while attenuating 13 cm echoes which would require a six fold thicker scattering layer if so we would expect each of the icy satellites average radar albedos to be higher at 2 2 cm than at 13 cm as is the case so far with rhea black g campbell d 2004 bull am astron soc 36 1123 as well as iapetus

dunes on titan observed by cassini radar thousands of longitudinal dunes have recently been discovered by the titan radar mapper on the surface of titan these are found mainly within 30 of the equator in optically near infrared and radar dark regions indicating a strong proportion of organics and cover well over 5 of titan s surface their longitudinal duneform interactions with topography and correlation with other aeolian forms indicate a single dominant wind direction aligned with the dune axis plus lesser off axis or seasonally alternating winds global compilations of dune orientations reveal the mean wind direction is dominantly eastwards with regional and local variations where winds are diverted around topographically high features such as mountain blocks or broad landforms global winds may carry sediments from high latitude regions to equatorial regions where relatively drier conditions prevail and the particles are reworked into dunes perhaps on timescales of thousands to tens of thousands of years on titan adequate sediment supply sufficient wind and the absence of sediment carriage and trapping by fluids are the dominant factors in the presence of dunes

radarclinometry of the sand seas of africa s namibia and saturn s moon titan abstract radarclinometry is a powerful technique for estimating heights of landforms in synthetic aperture radar sar images of planetary surfaces in particular it has been used to estimate heights of dunes in the sand seas of saturn s moon titan lorenz r d and 39 colleagues 2006 science 312 724 727 in this work we verify the technique by comparing dune heights derived from radarclinometry to known topography of dune fields in the namib sand sea of western africa we compared results from three different image grid spacings and found that 350 m pixel the same spacing at which the cassini radar data was processed is sufficient to determine dune height for dunes of similar morphometry to those of the namib sand sea at this grid spacing height estimates derived from radarclinometry are largely representative of though may underestimate by as much as 30 or overestimate by as much as 40 true dune height applying the technique to three regions on titan we estimate dune heights of 45 180 m and dune spacings of 2 3 3 3 km obtaining accurate heights of titan s dunes will help to constrain the total organic inventory on titan

radar bright channels on titan abstract during cassini s t44 flyby of titan may 28 2008 the cassini sar synthetic aperture radar revealed sinuous channels in the southwest of xanadu these channels feature very large radar cross sections up to 5 db whereas the angle of incidence was relatively high 20 this backscatter is larger than allowed by the coherent backscatter model considered to explain the unusual reflective and polarization properties of the icy satellites and only a few radar scattering mechanisms can be responsible for such high radar returns the presence of rounded icy pebbles with size larger than the radar wavelength 2 18 cm is proposed to explain the large radar cross sections measured in these units the radar bright channels are thus interpreted as riverbeds where debris likely shaped and transported by fluvial activity have been deposited similar debris were observed in the landing site of the huygens probe this work may point the way to an explanation for the enhanced brightness of other fluvial regions of titan

detection of iron substitution in natroalunite natrojarosite solid solutions and potential implications for mars natroalunite containing substantial amounts of fe occurs as a prominent secondary phase during acid sulfate alteration of pyroclastic basalts in volcanic fumaroles in nicaragua and elsewhere and has been observed in laboratory simulations of acid sulfate alteration as well reaction path models constrained by field and experimental observations predict that fe rich natroalunite should also form as a major secondary phase during alteration of martian basalt under similar circumstances here we evaluate the potential to use spectroscopic methods to identify minerals from the alunite group with chemical compositions intermediate between natroalunite and natrojarosite on the surface of mars and to remotely infer their fe contents x ray diffraction and spectroscopic measurements raman visible near infrared mid infrared mossbauer were obtained for a suite of synthetic solid solutions with a range of fe contents ranging from natroalunite to natrojarosite in the visible near infrared minerals with intermediate compositions display several spectral features not evident in end member spectra that could be used to remotely identify these minerals and infer their composition in addition raman spectra mid infrared spectra and x ray diffraction peaks all show systematic variation with changing fe content indicating that these methods could potentially be used to infer mineral compositions as well the results suggest that alunite group minerals with intermediate fe compositions may be able to account for some visible near infrared and mossbauer spectral features from mars that had previously been unidentified or attributed to other phases overall our findings indicate that consideration of solid solutions may lead to new identifications of alunite group minerals on the surface of mars and raise the possibility that minerals with compositions intermediate between natroalunite and natrojarosite may be widely distributed on the planet

global contraction expansion and polar lithospheric thinning on titan from patterns of tectonism we investigate the underlying physical processes that govern the formation and evolution of titan s tectonic features this is done by mapping mountain chains and hills using cassini radar data obtained during titan flybys t3 to t69 our mapping of mountain chains and hills reveals a global pattern east west orientations within 30 of the equator and north south between 60 latitude and the poles this result makes titan one of the few solar system bodies where global processes rather than regional processes dominate tectonism after comparison with five global stress models showing theoretical mountain chain orientations we suggest that either global contraction coupled with spin up or global expansion coupled with despinning could explain our observations if coupled with a lithosphere thinner in titan s polar regions

titan s surface from cassini radar sar and high resolution radiometry data of the first five flybys abstract the first five titan flybys with cassini s synthetic aperture radar sar and radiometer are examined with emphasis on the calibration and interpretation of the high resolution radiometry data acquired during the sar mode sar radiometry maps of the 2 cm wavelength brightness temperature are obtained coincident with the sar swath imaging with spatial resolution approaching 6 km a preliminary calibration shows that brightness temperature in these maps varies from 64 to 89 k surface features and physical properties derived from the sar radiometry maps and sar imaging are strongly correlated in general we find that surface features with high radar reflectivity are associated with radiometrically cold regions while surface features with low radar reflectivity correlate with radiometrically warm regions we examined scatterplots of the normalized radar cross section 0 versus brightness temperature finding differing signatures that characterize various terrains and surface features implications for the physical and compositional properties of these features are discussed the results indicate that volume scattering is important in many areas of titan s surface particularly xanadu while other areas exhibit complex brightness temperature variations consistent with variable slopes or surface material and compositional properties

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

akaganeite β feooh precipitation in inland acid sulfate soils of south western new south wales nsw australia abstract the prevalence of sulphidic sediments in inland wetlands has been only recently recognized in many parts of the world including australia the exposure of sulphidic sediments in these wetlands due to natural and human induced drying events has resulted in the oxidation of iron sulfide minerals the formation of secondary iron minerals characteristic of acid sulfate soils and the release of highly acidic solutions the objective of this study was to determine the mineralogy and morphology of sediments collected from the oxidized surface horizon 0 5 cm of an inland acid sulfate soil located in south western new south wales nsw australia random powder x ray diffraction xrd transmission electron microscopy tem and scanning transmission electron microscopy combined with energy dispersive x ray spectroscopy stem eds techniques were used to characterize the minerals present in these sediments akaganeite was identified as the major mineral phase in the sediments k jarosite was also determined in small amounts in some sediments the xrd patterns of sequentially washed e pure water 0 01 m hcl 0 01 m edta sediment samples showed all akaganeite peaks the rietveld refinement of these patterns also revealed a predominance of akaganeite the chemical analyses of the original and washed sediments using stem eds clearly showed the presence of akaganeite as a pure mineral phase with an average fe cl mole ratio of 6 7 and a structural formula of fe 8 o 8 oh 6 8 cl 1 2 these findings show that the extreme saline acidic solutions ph 2 ec 216 ds m at the bottle bend lagoon provide ideal conditions for the crystallization of this rarely forming mineral

creation and destruction of weddell sea floor in the jurassic new paleomagnetic data invite reassessment of the breakup history of parts of the pacific margin of gondwana due to the mesozoic opening of the southern ocean basins these data indicate clockwise rotation of the antarctic peninsula relative to east antarctica between 175 and 155 ma that would have created as much as 1000 km of pre anomaly m25 ocean floor in the weddell sea basin the paleomagnetic data also suggest that between 155 and 130 ma the antarctic peninsula rotated counterclockwise relative to east antarctica rotation that along with the southward motion of east antarctica would have caused subduction of the newly created weddell sea ocean floor beneath the southern antarctic peninsula east vergent folding and thrusting of jurassic back arc basin rocks along the southeastern antarctic peninsula known as the palmer land event probably resulted from deformation along this newly created convergent margin the presence of jurassic weddell sea floor would have isolated eastern gondwana east antarctica australia and india from the antarctic peninsula and western gondwana africa and south america encouraging increased marine faunal connections between the pacific and weddell sea mozambique somali ocean basins during the 175 to 130 ma interval after 130 ma the antarctic peninsula would have been connected to east antarctica via the other west antarctic terranes thereby facilitating land migrations between eastern and western gondwana

resurfacing of titan by ammonia water cryomagma the cassini titan radar mapper observed on titan several large features interpreted as cryovolcanic during the october 26 2004 pass at high northern latitudes lopes r m c and 43 colleagues 2007 icarus 186 395 412 to date models of ammonia water resurfacing have not been tied to specific events or evolutionary stages of titan we propose a model of cryovolcanism that involves cracking at the base of the ice shell and formation of ammonia water pockets in the ice as these ammonia water pockets undergo partial freezing in the cold ice shell the ammonia concentration in the pockets increases decreasing the negative buoyancy of the ammonia water mixture if the ice shell is contaminated by silicates delivered in impacts the liquid solid density difference would be even less while the liquid cannot easily become buoyant relative to the surrounding ice these concentrated ammonia water pockets are sufficiently close to the neutral buoyancy point that large scale tectonic stress patterns tides non synchronous rotation satellite volume changes solid state convection or subsurface pressure gradients associated with topography would enable the ammonia to erupt effusively onto the surface rather than suggesting steady state volcanism over the history of the solar system we favor a scenario where the cryovolcanic features could have been associated with episodic potentially late geological activity

titan s surface revealed by hst imaging we present for the first time relative albedo maps of titan s surface the maps were made from images taken by the hubble space telescope s planetary camera 295 km per pixel through atmospheric windows at 940 and 1080 nm coverage at all longitudes and between 45 s and 60 n was obtained with 14 orbits from 4 18 october 1994 each image is characterized by haze with both limb effects brightening and a large north south contrast subtracting an averaged image from each frame removes haze effects and reveals surface features of 10 maximum contrast many features are clearly visible in multiple images and in both filters but the surface map is dominated by a large bright roughly rectangular feature centered at 110 w 10 s and elongated in an east west direction 4000 2500 km2 this feature and others indicate the diversity of titan s surface we consider the origin of the bright feature in an otherwise dark landscape and suggest that highland washing by methane rainfall is a likely mechanism

mossbauer mineralogy of rock soil and dust at meridiani planum mars opportunity s journey across sulfate rich outcrop basaltic sand and dust and hematite lag deposits additonal co authors p gutlich e kankeleit t mccoy dw mittlefehldt f renz me schmidt b zubkov sw squyres re arvidson

titan s diverse landscapes as evidenced by cassini radar s third and fourth looks at titan abstract cassini s third and fourth radar flybys t7 and t8 covered diverse terrains in the high southern and equatorial latitudes respectively the t7 synthetic aperture radar sar swath is somewhat more straightforward to understand in terms of a progressive poleward descent from a high dissected and partly hilly terrain down to a low flat plain with embayments and deposits suggestive of the past or even current presence of hydrocarbon liquids the t8 swath is dominated by dunes likely made of organic solids but also contain somewhat enigmatic probably tectonic features that may be partly buried or degraded by erosion or relaxation in a thin crust the dark areas in t7 show no dune morphology unlike the dark areas in t8 but are radiometrically warm like the dunes the huygens landing site lies on the edge of the t8 swath correlation of the radar and huygens disr images allows accurate determination of its coordinates and indicates that to the north of the landing site sit two large longitudinal dunes indeed had the huygens probe trajectory been just 10 km north of where it actually was images of large sand dunes would have been returned in place of the fluvially dissected terrain actually seen illustrating the strong diversity of titan s landscapes even at local scales

the sand seas of titan cassini radar observations of longitudinal dunes the most recent cassini radar images of titan show widespread regions up to 1500 kilometers by 200 kilometers of near parallel radar dark linear features that appear to be seas of longitudinal dunes similar to those seen in the namib desert on earth the ku band 2 17 centimeter wavelength images show 100 meter ridges consistent with duneforms and reveal flow interactions with underlying hills the distribution and orientation of the dunes support a model of fluctuating surface winds of 0 5 meter per second resulting from the combination of an eastward flow with a variable tidal wind the existence of dunes also requires geological processes that create sand sized 100 to 300 micrometer particulates and a lack of persistent equatorial surface liquids to act as sand traps

distribution and interplay of geologic processes on titan from cassini radar data abstract the cassini titan radar mapper is providing an unprecedented view of titan s surface geology here we use synthetic aperture radar sar image swaths ta t30 obtained from october 2004 to december 2007 to infer the geologic processes that have shaped titan s surface these sar swaths cover about 20 of the surface at a spatial resolution ranging from 350 m to 2 km the sar data are distributed over a wide latitudinal and longitudinal range enabling some conclusions to be drawn about the global distribution of processes they reveal a geologically complex surface that has been modified by all the major geologic processes seen on earth volcanism tectonism impact cratering and erosion and deposition by fluvial and aeolian activity in this paper we map geomorphological units from sar data and analyze their areal distribution and relative ages of modification in order to infer the geologic evolution of titan s surface we find that dunes and hummocky and mountainous terrains are more widespread than lakes putative cryovolcanic features mottled plains and craters and crateriform structures that may be due to impact undifferentiated plains are the largest areal unit their origin is uncertain in terms of latitudinal distribution dunes and hummocky and mountainous terrains are located mostly at low latitudes less than 30 with no dunes being present above 60 channels formed by fluvial activity are present at all latitudes but lakes are at high latitudes only crateriform structures that may have been formed by impact appear to be uniformly distributed with latitude but the well preserved impact craters are all located at low latitudes possibly indicating that more resurfacing has occurred at higher latitudes cryovolcanic features are not ubiquitous and are mostly located between 30 and 60 north we examine temporal relationships between units wherever possible and conclude that aeolian and fluvial pluvial lacustrine processes are the most recent while tectonic processes that led to the formation of mountains and xanadu are likely the most ancient

mapping and interpretation of sinlap crater on titan using cassini vims and radar data 1 only a few impact craters have been unambiguously detected on titan by the cassini huygens mission among these sinlap is the only one that has been observed both by the radar and vims instruments this paper describes observations at centimeter and infrared wavelengths which provide complementary information about the composition topography and surface roughness several units appear in vims false color composites of band ratios in the sinlap area suggesting compositional heterogeneities a bright pixel possibly related to a central peak does not show significant spectral variations indicating either that the impact site was vertically homogeneous or that this area has been recovered by homogeneous deposits both vims ratio images and dielectric constant measurements suggest the presence of an area enriched in water ice around the main ejecta blanket since the ku band sar may see subsurface structures at the meter scale the difference between infrared and sar observations can be explained by the presence of a thin layer transparent to the radar an analogy with terrestrial craters in libya supports this interpretation finally a tentative model describes the geological history of this area prior during and after the impact it involves mainly the creation of ballistic ejecta and an expanding plume of vapor triggered by the impact followed by the redeposition of icy spherules recondensed from this vapor plume blown downwind subsequent evolution is then driven by erosional processes and aeolian deposition

episodic rapid uplift in the himalaya revealed by 40ar 39ar analysis of detrital k feldspar and muscovite bengal fan detrital k feldspar and muscovite samples from ocean drilling program leg 116 cores have been dated by the sup 40 ar sup 39 ar technique and have depositional ages from 0 to 18 ma from 4 to 13 individual k feldspars and 1 to 12 individual muscovites have been dated from 7 stratigraphic levels in every level at least one k feldspar and one muscovite yielded a minimum age identical within uncertainty to the age of deposition these results indicate that a significant portion of the material in the bengal fan is first cycle detritus derived from the himalaya therefore the substantial amount of sediment deposited in the distal fan in early to middle miocene time can be ascribed to a significant pulse of uplift and erosion in the collision zone at this time moreover these data indicate that throughout the neogene some part of the himalayan orogen was undergoing rapid erosion 1 to 10 mm yr this erosion must have been less than or equal to uplift relative to sea level the lack of granulite facies rocks in the eastern himalaya and tibetan plateau suggests to us that very rapid uplift must have been distributed in brief pulses over different parts of the mountain belt these datamore are incompatible with tectonic models in which the himalaya and tibetan plateau are uplifted either uniformly over the past 40 m y or mostly within the past 2 to 5 m y less

field study of a highly active fault zone the xianshuihe fault of southwestern china the xianshuihe fault of western sichuan province china is one of the world s most active faults having produced 4 earthquakes during this century of magnitude 7 along a 350 km length of the fault at least 8 such events have occurred since 1725 in the more limited 150 km long segment including luhuo and daofu major earthquakes in 1904 1923 1973 and 1981 m 7 7 7 6 6 9 were associated with overlapping surficial fault ruptures and with individual left lateral displacements as large as 3 6 m field studies indicate that this high degree of activity is typical of the fault s longer term history the holocene left lateral slip rate on the north western segment of the fault has been 15 5 mm yr decreasing to about 5 mm yr on its southeastern segment based on radiometrically dated offset stream channel and terrace deposits and on offset glacial moraines physiographic features of active faulting are fully as diagrammatic as those of california s san andreas fault mainly because of high altitude preservation and the absence of cultural modification on this eastern margin of the tibetan plateau detailed en echelon tensional and pushup features resulting from surface ruptures in 1973 1955 1923 and 1893 can still be recognized today and new data have been collected bearing on the offsets and fault rupture lengths during these and other events the locations and magnitudes of historic earthquakes suggest that the characteristic earthquake model may apply to the xianshuihe fault obvious geometric segmentation of the fault has controlled the initiation and termination of ruptures in some events whereas segmentation control for others remains obscure based on the historic record repeat times estimated from slip rates and current seismic gaps two segments are particularly likely sites for m 7 earthquakes in the near future the 65 km long segment between daofu and qianning and the 135 km long segment bracketing kangding continuing creep has been documented along some segments of the fault and this together with the high degree of activity and other unique attributes makes the xianshuihe fault one of the most promising sites in the world for earthquake prediction and hazard evaluation studies

active faulting and tectonics of burma and surrounding regions this study of the active tectonics of burma and surrounding regions is based mostly on an interpretation of landsat imagery and on fault plane solutions for shallow and intermediate earthquakes fold axes in the indoburman ranges and an east dipping inclined zone of intermediate depth earthquakes suggest that a slab of oceanic lithosphere was recently subducted to the east under the indoburman ranges fault plane solutions of shallow earthquakes however do not show underthrusting at the present time instead p axes are oriented roughly north south parallel not perpendicular to the fold axes in the ranges p axes for fault plane solutions of intermediate shocks also trend north south parallel to the strike of the subducted slab and may indicate that the hanging slab is being dragged north by india through the surrounding asthenosphere the sagaing fault probably accommodates most of the right lateral slip of india past indochina but india s northward movement also causes internal deformation within burma thailand and yunnan differences between the tectonic fabric seen on the landsat images and the tectonic regime compatible with the fault plane solutions throughout the region imply major changes in the directions of relative motion in the orientations of strain and in the style of deformation in the late cenozoic presumably these changes reflect the transition from subduction to collision and strike slip motion as india penetrated into eurasia past burma large parts of burma and thailand may have rotated several tens of degrees clockwise in this process

faulting associated with large earthquakes and the average rate of deformation in central and eastern asia we determine approximate average rates of deformation in portions of eastern and central asia for the last 80 years these rates are based on estimates of source dimensions average displacements seismic moments and orientations of faults of all large earthquakes m 7 5 and as many other major earthquakes m 7 0 as possible in asia since 1900 a major part of this study is the compilation of these data for separate parts of asia we combine seismic moment tensors to estimate the average rotational strain or deformation tensors for these regions for the last 80 years we estimate that shortening across the tien shan has occurred at 11 mm yr between 5 and 19 mm yr left lateral shear on easterly trending planes in mongolia in northwestern tibet gansu and ningxia and on the xianshuihe fault in western sichuan has been very rapid more than 10 mm yr in each region and apparently as rapid as 40 mm yr in northwestern tibet gansu and ningxia slower rates of a few to 10 mm yr appear to characterize east west extension and conjugate north south shortening of tibet the earthquake history of the himalaya is consistent with rates of underthrusting of more than 10 mm yr but is probably less than the convergence rate of india with eurasia of about 50 mm yr the overall strain field is consistent with a large part of india s penetration into eurasia being absorbed by the extrusion of material out of india s way as a result southeast china moved at about 21 mm yr east southeast with respect to eurasia in the last 80 years with an uncertainty of about a factor of 2 in this estimated rate

mapping of titan results from the first titan radar passes the first two swaths collected by cassini s titan radar mapper were obtained in october of 2004 ta and february of 2005 t3 the ta swath provides evidence for cryovolcanic processes the possible occurrence of fluvial channels and lakes and some tectonic activity the t3 swath has extensive areas of dunes and two large impact craters we interpret the brightness variations in much of the swaths to result from roughness variations caused by fracturing and erosion of titan s icy surface with additional contributions from a combination of volume scattering and compositional variations despite the small amount of titan mapped to date the significant differences between the terrains of the two swaths suggest that titan is geologically complex the overall scarcity of impact craters provides evidence that the surface imaged to date is relatively young with resurfacing by cryovolcanism fluvial erosion aeolian erosion and likely atmospheric deposition of materials future radar swaths will help to further define the nature of and extent to which internal and external processes have shaped titan s surface

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

mineralogy composition and alteration of mars pathfinder rocks and soils evidence from multispectral elemental and magnetic data on terrestrial analogue snc meteorite and pathfinder samples major element multispectral and magnetic properties data were obtained at ares vallis during the mars pathfinder mission to understand the compositional mineralogical and process implications of these data we obtained major element mineralogical and magnetic data for well crystalline and nanophase ferric minerals terrestrial analogue samples with known geologic context and snc meteorites analogue samples include unaltered palagonitic and sulfatetic tephra from mauna kea volcano hydrolytic and acid sulfate alteration steam vent material from kilauea volcano hydrolytic alteration and impactites from meteor crater relithification salient results for mars pathfinder include 1 band depths bd530b and bd600 and the reflectivity ratio r800 r750 are consistent with the dominant ferric mineral being nanophase ferric oxide associated with an unknown amount of h2o and occurring in composite particles along with subordinate amounts of other ferric minerals hematite and hematite plus nanophase goethite are most consistent with the data but maghemite akaganeite schwertmannite and nanophase lepidocrocite are also possible interpretations ferric oxides that are consistently not favored by the data as sole alteration products are jarosites and well crystalline goethite and lepidocrocite 2 the strength of the ferric adsorption edge r750 r445 implies the fe3 fe2 values for pathfinder rock and soil are within the ranges 0 7 3 and 3 20 respectively 3 ferrous silicates are indicated for subsets of pathfinder rocks and soils one subset has a band minimum near 930 nm that can attributed to low ca pyroxene alternatively the band could be a second manifestation of certain ferric oxides including nanophase goethite maghemite akaganeite and schwertmannite another subset has a negative spectral slope from 800 to 1005 nm which could result from the high energy wing of a high ca pyroxene and or olivine band a mixture of bright and dark materials and for rocks thin coatings of bright dust on dark rocks 4 chemical data on pathfinder rocks and soils are consistent with two component mixtures between an andesitic rock with low mgo and so3 concentrations soil free rock and a global basaltic soil with high mgo and so3 concentrations rock free soil pathfinder rock free soil can be modeled as a chemical mixture of snc meteorites and the pathfinder soil free rock 5 pathfinder soil cannot be obtained by chemical alteration of pathfinder rocks by any of the hydrolytic and acid sulfate alteration processes we studied presumably global mixing has obscured and possibly erased the elemental signatures of chemical alteration 6 the strongly magnetic phase in palagonitic and sulfatetic tephra is titanomagnetite and possibly its oxidation product titanomaghemite fe ti spinels the saturation magnetization of the tephra samples 0 5 2 0 am2 kg is at or below the low end of the range inferred for martian dust 4 2 am2 kg implying that lithogenic fe ti spinels are a possible candidate for the martian strongly magnetic phase 7 the predominantly palagonitic spectral signature and magnetic nature of martian soil and dust are consistent with glassy precursors with imbedded fe ti spinel particles comparison with lunar glass production rates suggests that production of sufficient quantities of glassy materials on mars by volcanic and impact processes is sufficient to account for these observations

mountains on titan observed by cassini radar abstract the cassini titan radar mapper has observed elevated blocks and ridge forming block chains on saturn s moon titan demonstrating high topography we term mountains summit flanks measured from the t3 february 2005 and t8 october 2005 flybys have a mean maximum slope of 37 and total elevations up to 1930 m as derived from a shape from shading model corrected for the probable effects of image resolution mountain peak morphologies and surrounding diffuse blankets give evidence that erosion has acted upon these features perhaps in the form of fluvial runoff possible formation mechanisms for these mountains include crustal compressional tectonism and upthrusting of blocks extensional tectonism and formation of horst and graben deposition as blocks of impact ejecta or dissection and erosion of a preexisting layer of material all above processes may be at work given the diversity of geology evident across titan s surface comparisons of mountain and blanket volumes and erosion rate estimates for titan provide a typical mountain age as young as 20 100 million years

observations of the surface of titan by the radar altimeters on the huygens probe abstract results from the radar altimeters on board the huygens probe are reported noting the content of data archived on the nasa planetary data system and its esa counterpart these instruments provide unique high resolution information on the topography and electrical properties of the titan surface over a 15 km track across a boundary between a bright highland and the dark dissected alluvial terrain on which the probe landed the highland appears 100 m higher than the dark terrain the dark terrain has a fairly high nadir radar backscatter consistent with terrestrial lakebeds and alluvial surfaces and shows small 5 10 m elevation fluctuations possible signatures of surface or volume scattering in the backscatter amplitude and intermediate frequency spectrum are discussed a previously undocumented characteristic of the automatic gain control agc on the flight altimeter is noted

mineralogy of a mudstone at yellowknife bay gale crater mars sedimentary rocks at yellowknife bay gale crater on mars include mudstone sampled by the curiosity rover the samples john klein and cumberland contain detrital basaltic minerals calcium sulfates iron oxide or hydroxides iron sulfides amorphous material and trioctahedral smectites the john klein smectite has basal spacing of similar to 10 angstroms indicating little interlayer hydration the cumberland smectite has basal spacing at both similar to 13 2 and similar to 10 angstroms the larger spacing suggests a partially chloritized interlayer or interlayer magnesium or calcium facilitating h2o retention basaltic minerals in the mudstone are similar to those in nearby eolian deposits however the mudstone has far less fe forsterite possibly lost with formation of smectite plus magnetite late noachian early hesperian or younger age indicates that clay mineral formation on mars extended beyond noachian time

nyainqentanglha shear zone a late miocene extensional detachment in the southern tibetan plateau a major low angle ductile shear zone containing s c mylonites involves metamorphosed granitic rocks at the southeastern edge of the nyainqentanglha mountain range southern tibet prominent triangular facet geomorphology is developed by valley erosion of the detachment surface defined by the top of the southeast dipping mylonitec shear zone kinematic criteria consistently indicate a top to southeast sense of shear the ductile shearing deformation is inferred from isotopic cooling ages to have occurred during the interval 11 5 ma late miocene we interpret the shear zone as a regional extensional detachment its development indicates when the extensional tectonics in this area started which in turn may mark the time when the maximum sustainable surface elevation and perhaps crustal thickness was reached in southern tibet

tectonic evolution of high plateaus abstract the striking contrast in tectonic style between highlands like tibet with its active grabens and low altitude flanks like the thrusting structures in the foothills of the himalayas shows that a disorder of the tectonic stresses correlates with the topography the same is true for gravity in particular for the geoid as clearly observed in the case of the altiplano these observations can be explained physically by means of simple relationships between the dipolar mass distribution of the high topography and its compensating root this analysis leads to a proposed scenario for plateau evolution in three stages 1 1 build up with thrusting and folding 2 2 neutral state or strike slip deformation and finally 3 3 relaxation with normal faulting the basin and range represents a mature illustration of phase 3 its bouguer anomaly suggests the existence of an undulation of the lithosphere astenosphere boundary with a 200 km wavelength physical models of lithospheric boudinage are shown for one to compare with the observed topographic and gravimetric signatures

oman exotics oceanic carbonate build ups associated with the early stages of continental rifting the so called oman exotic limestones form isolated masses from boulder size to 1 000 m thick of middle to upper permian and upper triassic fossiliferous limestones and crop out within imbricated thrust slices beneath the semail ophiolite in the oman mountains permian exotics are of dominantly reef and forereef facies whereas triassic exotics are more typically of back reef and lagoonal facies they are commonly associated with a substrate of alkalic and transitional tholeiitic basalts and are interpreted as a series of reef associated carbonate buildups deposited in part on oceanic islands or seamounts close to the site of initial rifting of the oman continental margin

cryovolcanic features on titan s surface as revealed by the cassini titan radar mapper abstract the cassini titan radar mapper obtained synthetic aperture radar images of titan s surface during four fly bys during the mission s first year these images show that titan s surface is very complex geologically showing evidence of major planetary geologic processes including cryovolcanism this paper discusses the variety of cryovolcanic features identified from sar images their possible origin and their geologic context the features which we identify as cryovolcanic in origin include a large 180 km diameter volcanic construct dome or shield several extensive flows and three calderas which appear to be the source of flows the composition of the cryomagma on titan is still unknown but constraints on rheological properties can be estimated using flow thickness rheological properties of one flow were estimated and appear inconsistent with ammonia water slurries and possibly more consistent with ammonia water methanol slurries the extent of cryovolcanism on titan is still not known as only a small fraction of the surface has been imaged at sufficient resolution energetic considerations suggest that cryovolcanism may have been a dominant process in the resurfacing of titan

crustal volume balance during the india eurasia collision and altitude of the tibetan plateau a working hypothesis a working hypothesis is developed for the two stages of evolution of the tibetan plateau during the continental collision between india and eurasia the first phase was dominated by crustal shortening and thickening in what is now tibet while indochina was expelled southeastward away from eurasia at the end of this phase at 17 ma the estimated tibetan crustal thickness was 51 km the second phase has been dominated by thickening of tibet by the influx of crustal material from india with no associated crustal shortening the crustal thickening that is inferred to have occurred by this process is only feasible because leakage of crust from beneath the plateau is restricted by neighboring archean cratons that block lower crustal flow this leakage to the east and south from tibet to beneath yunnan is estimated as 20 30 of the influx at present but was much smaller at the start of this second phase of deformation it is suggested that at 11 ma the force exerted against the tibetan upper crust by this flowing material first exceeded the threshold that this brittle layer could resist and tibet began to extend eastward any satisfactory working hypothesis for the tibetan plateau must explain its dimensions its 17 ma ending of shortening and 11 ma start of extension and volcanism the eastward slip sense on its active normal and strike slip faults and the ratios of their displacements to present day slip rates which imply that their slip rates have gradually increased this working hypothesis accounts for these features and predicts a smooth and continuing increase in altitude

effect of solution ph and chloride concentration on akaganeite precipitation implications for akaganeite formation on mars akaganeite beta feooh chloride containing fe iii hydr oxide has been recently discovered on the surface of mars by the mars science laboratory curiosity rover in yellowknife bay gale crater mars 1 and from orbit by the mars reconnaissance orbiter in robert sharp crater and antoniadi basin 2 however the mechanism and aqueous environmental conditions of akaganeite formation e g ph and chloride concentration remain unknown we have investigated formation of akaganeite through fe iii hydrolysis at variable initial ph and chloride concentrations the formed fe iii precipitates were characterized by instruments similar to instruments on mars robotic spacecraft syntheses were performed through hydrolysis of fe iii perchlorate with addition of na cloride fe cl ratio between 0 5 and 5 and at initial ph of 1 5 2 4 6 and 8 at 90degc x ray diffraction analysis revealed formation of akaganeite alone or in mixture with goethite hematite and ferrihydrite at all initial phs and fe cl ratio between 0 5 and 2 while akaganeite precipitated only at ph 1 5 and fe cl greater than2 chloride content of akaganeite was affected by initial ph and decreased from 20 60 mg g at ph 1 5 to less than 0 1 mg g at ph 8 the synthesized akaganeite samples were also characterized by mssbauer and infrared spectroscopy and volatiles were analysed by thermal and evolved gas analysis the obtained characterization data will be compared to published data from rover and orbital missions 1 3 to determine martian akaganeite composition crystallinity and formation conditions