valles marineris dune sediment provenance and pathways abstract although low albedo sand is a prevalent component of the martian surface sources and pathways of the sands are uncertain as one of the principal present day martian sediment sinks the valles marineris vm rift system hosts a diversity of dune field populations associated with a variety of landforms that serve as potential sediment sources including spur and gully walls interior layered deposits ilds and landslides here we test the hypothesis that vm dune fields are largely derived from a variety of local and regional intra rift sediment sources results show several dune fields are superposed on ancient wall massifs and ilds that are topographically isolated from extra rift sand sources spectral analysis of dune sand reveals compositional heterogeneity at the basinal dune field and dune scales arguing for discrete relatively unmixed sediment sources in coprates and melas chasmata mapping is consistent with the principle sand source for dunes being noachian aged upper and lower wall materials composed of primary igneous minerals and glasses some of which show evidence for alteration in contrast dune fields in capri juventae and ganges chasmata show evidence for partial sediment derivation from adjacent early hesperian aged hydrated sulfate bearing ild units this finding indicates that these ilds act as secondary sand sources dunes containing soft secondary minerals e g monohydrated sulfate are unlikely to have been derived from distant sources due to the physical weathering of sand grains during transport isolated extra rift dune fields sand sheets and sand patches are located on the plateaus surrounding vm and the adjoining areas but do not form interconnected networks of sand pathways into the rift if past wind regimes with respect to directionality and seasonality were consistent with more recent regimes inferred from morphological analysis i e dune slip faces wind streaks and were sufficient in strength and duration small dune populations within aurorae chaos and north of eastern vm might have resulted from extended sand pathways into vm however we favor local and regional derivation of dune sand from a variety of intra rift lithologic sources for most cases dune sand sources and the mechanism by which the sand is liberated are discussed in the context of findings described herein but are broadly applicable to analysis of sediment production elsewhere on mars

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

late weichselian glacier retreat in kongsfjorden west spitsbergen svalbard the chronology of late weichselian to holocene deglaciation of kongsfjorden west spitsbergen has been reconstructed based on the geomorphic and stratigraphic record of ice retreat relative sea level relationships and 14c dating of associated marine organic materials the seaward extent of glacial drift and fjord bathymetry constrain a secure reconstruction for the ice sheet near the mouth of the fjord at ca 13 000 yr b p but do not rule out the possibility that more extensive glaciation was achieved earlier during the late weichselian regional shoreline relations rates of emergence and radiocarbon dating of foraminifera deposited just above till indicate that deglaciation occurred in two steps one beginning during or just prior to the late weichselian marine limit phase at 13 000 12 000 yr b p and another beginning at 10 000 9500 yr b p the fjord was completely deglaciated by 9440 130 yr b p a period of stable relative sea level began 10 700 yr b p and ended between 10 000 and 9500 yr b p which we take to indicate renewed glacial loading during the younger dryas glacier readvance within kongsfjorden at this time was diminutive suggesting that most of the younger dryas ice sheet growth was confined to the eastern part of the archipelago and or to the barents shelf the two step deglaciation of kongsfjorden occurred during intervals of accelerated global ice sheet melting and rapid oceanic and atmospheric warming in more temperate latitudes of the circum atlantic region this coincidence most likely resulted from contemporaneous increases in the poleward transport of oceanic heat

rate of wind abrasion on mars estimation of the rate of aeolian abrasion of rocks on mars requires knowledge of 1 particle flux 2 susceptibilities to abrasion of various rocks and 3 wind frequencies on mars fluxes and susceptibilities for a wide range of conditions were obtained in the laboratory and combined with wind data from the viking meteorology experiment assuming an abundant supply of sand sized particles estimated rates range up to 2 1 10 2 cm of abrasion per year in the vicinity of viking lander 1 this rate is orders of magnitude too great to be in agreement with the inferred age of the surface based on models of impact crater flux the discrepancy in the estimated rate of abrasion and the presumed old age of the surface cannot be explained easily by changes in climate or exhumation of ancient surfaces we consider the primary reason to be related to the agents of abrasion either windblown grains are in very short supply or the grains are ineffective as agents of abrasion at least some sand sized 100 m grains appear to be present as inferred from both lander and orbiter observations high rates of abrasion occur for all experimental cases involving sands of quartz basalt or ash however previous studies have shown that sand is quickly comminuted to silt and clay sized grains in the martian aeolian regime experiments also show that these fine grains are electrostatically charged and bond together as sand sized aggregates laboratory simulations of wind abrasion involving aggregates show that at impact velocities capable of destroying sand aggregates form a protective veneer on the target surface and can give rise to extremely low abrasion rates

dark aeolian sediments in martian craters composition and sources our research focuses on the mineralogical characteristics of dark sediment deposits in martian craters dunes dune fields and sand sheets and their local sediment sources carried out on the basis of 70 selected localities morphological analyses reveal dark layers exposed in a number of crater walls showing indications of material transport from the layers downwall to the intracrater deposits additional sites show dark sediment emerging from several craters floors suggesting a dark material source beneath the crater floor spectral analyses of omega and crism data showed for the first time that a direct mineralogical connection exists between the dark layers in the crater walls and the intracrater dune and sand sheet material based on these findings it is shown that these layers are the local sources for the dark aeolian sediment inside the craters spectral analyses further indicate that all deposits are nearly of the same mafic mineralogical composition hinting at a similar origin we conclude that the mineralogical composition points to a volcanic origin of the material the dark layers which we infer to be the material sources might represent layers of volcanic ash almost globally deposited in early noachian times and subsequently covered by regolith groundwater impact erosion and crustal movement led to the highly fragmented situation of the dark layers today however burial protected the layers of dark sediment from chemical alteration caused by surficial fluvial processes impact erosion after the wet periods on mars led to the exposure and mobilization of the material today

quantitative compositional analysis of martian mafic regions using the mex omega reflectance data 2 petrological implications abstract the primary objectives of this paper are to determine the modal mineralogy of selected low albedo terrains of different ages ranging from noachian to amazonian exposed on the surface of mars this analysis is conducted using the spectral modeling of the observatoire pour la mineralogie l eau les glaces et l activite omega reflectance data results from this work are consistent with the major results of previous spectroscopic studies plagioclase 40 60 in volume and high calcium pyroxene 20 40 hcp are the dominant minerals of the most regions low calcium pyroxene 10 15 lcp and minor amounts of olivine are also present the oldest terrains are characterized by the largest amount of lcp and the lowest concentration of plagioclase these overall compositions are consistent with two pyroxene basalts the particle sizes are in the range of a few hundreds of micrometers which is in good agreement with the thermal inertia of the martian low albedo regions in the region around the nili fossae localized concentrations of olivine up to 40 with millimeter particle size similar to picritic basalts observed in situ by the spirit rover in the gusev crater are inferred chemical compositions are calculated for the first time from omega spectra they are quite consistent with gusev rocks and shergottite compositions but they appear to be significantly sio2 poorer than thermal emission spectrometer data a decreasing low calcium pyroxene abundance with the decreasing age of the low albedo regions is reported this may be indicative of decreasing degree of partial melting as thermal flux decreases with time we propose that the ancient noachian aged lcp rich terrains could have been formed from h2o bearing melts then dry basaltic volcanism occurred leading to decreasing lcp abundance with time due to decreasing degree of partial melting the olivine bearing material modeled in nili fossae resembles the composition of alh77005 and chassigny meteorites consistent with prior studies implications on the formation of the basaltic shergottites are discussed

volcaniclastic aeolian deposits at sunset crater arizona terrestrial analogs for martian dune forms sunset crater in north central arizona usa is a 900 year old scoria cone volcano wind action has redistributed its widespread tephra deposit into a variety of aeolian dune forms that serve as a terrestrial analog for similar landforms and aeolian processes on mars fieldwork was conducted to collect essential geomorphological and sedimentological data and to establish a baseline for the type and morphometry of dunes physical properties interactions with topography and saltation pathways our analyses focused primarily on coppice dunes falling dunes wind ripples and sand streaks for all collected volcaniclastic aeolian sediment samples the sand size fraction dominated ranging from almost 100 sand to 74 6 sand no sample contained more than 1 6 silt the composition is overwhelmingly basaltic with non basaltic particles composing 2 to 6 of the total coppice nebkha dunes form where clumps of vegetation trap saltating particles and create small mounds or hummocks mean grain size for coppice dune samples is coarse sand measured dune height for 15 coppice dunes ranged from 0 3 to 3 3 m with a mean of 1 m mean length was 6 7 m and mean width was 4 8 m falling dunes identified in this study are poorly developed and thin lacking a prominent ramp like structure mean wavelength for three sets of measured ripples ranged from 22 to 36 cm sand streaks extend downwind for more than a kilometer and are up to 200 m in width they commonly occur on the lee side of mesas and similar landforms and are typically the downwind continuation of falling dunes falling dunes wind ripples and sand streaks have been identified on mars while coppice dunes are similar to martian shadow or lee dunes in which sand accumulates in the lee of obstacles copyright 2012 john wiley sons ltd

a crested theropod dinosaur from antarctica jurassic fossil vertebrates collected from the falla formation in the central transantarctic mountains included a partial skull and postcranial elements of a crested theropod cryolophosaurus ellioti gen nov sp nov the theropod bears some resemblance to the large tetanurans of the middle to late jurassic but also has primitive ceratosaurian features elements from a prosauropod teeth from scavenging theropods a pterosaur humerus and a tritylodont molar were also recovered the presence of this fauna suggests that a mild climate existed at high paleolatitude in this area of gondwana during the early jurassic

marine eemian and early weichselian deposits in northern denmark a review of the foraminiferal stratigraphy abstract a marine eemian transgression has been registered in many areas of denmark not only near the coast but also in broad deep embayments a marine eemian sequence substage 5e of 25 60 m thickness occurs in a deep structurally controlled northwest southeast trending basin across north jutland the foraminiferal faunas reflect boreal lusitanian marine environments corresponding to conditions off western france today certain elements of the faunas are however only known from the mediterranean sea the assemblages in the succeeding 20 40 m thick marine unit reveal a drop in sea level of more than 50 m and a subsequent lowering in temperature this sequence has been correlated with oxygen isotope substages 5d 5a and is referred to the early weichselian

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

volcanism on mars more than 15 years of planetary exploration of mars have given insight into the geologic processes that have shaped its surface the newly acquired viking data have shown that volcanism is one of the most important geologic processes operating on mars throughout its history in situ chemical analyses of martian soil by the viking lander spacecraft indicate mafic to ultramafic source rocks this is consistent both with available remote sensing data which indicate the presence of mafic minerals such as pyroxene and olivine and with petrologic modeling based on available geophysical data which suggest that martian lavas are probably iron rich and ultramafic these data strongly suggest that basaltic volcanism is widespread on mars and much of the photogeological data may be studied in this context photogeological analysis of the martian surface has shown two main types of volcanic morphologies the first type is central volcanoes which are volcanic landforms developed by continued and prolonged eruption from a point source vent this category includes 1 shields the classic low profile volcanic mountains of which olympus mons is the most spectacular example 2 domes steep sided constructs such as tharsis tholus that may represent lower rates of eruption than the shields or possibly more silicic lava compositions 3 highland patera radially textured low profile volcanoes that occur in the cratered terrain and are interpreted as ash shields 4 alba patera an apparently unique volcanic landform consisting of a vast volcanic center over 1500 km across with flank slopes of less than a tenth of a degree and 5 various small features such as cinder cones the second major category is volcanic plains which are units recognized by several criteria of which the presence of mare ridges and flow lobes are the most useful volcanic plains are subdivided into four main groups 1 simple flows broad smooth to rolling plains that contain numerous mare type ridges but no flow lobes interpreted as being composed of thick single cooling units 2 complex flows displaying multiple overlapping flow lobes interpreted to be indicative of thin multiple cooling units 3 undifierentiated flows plains that typically lack any morphologic identifying feature but are considered to be volcanic partly on the basis of their association with large volcanic centers and 4 questionable plains volcanic units heavily modified by other processes erosion tectonism etc so that their origins are uncertain when these categories of volcanic morphologies are combined with relative age data provided by crater statistics a volcanic history for mars can be derived as follows early heavy bombardment of mars was accompanied and followed by small scale fluvial channeling extensive flood volcanism the plateau plains and ash shield volcanism in the cratered terrain shortly after this time less extensive flood volcanism continued to resurface the planet during formation of the northern southern hemisphere dichotomy central volcanism became more prominent with the development of the alba patera center as well as the older shields and domes of the northern hemisphere early tharsis and elysium regions the development of the tharsis and elysium uplifts may have triggered the release of large scale catastrophic floods producing large channels continued uplift and lithospheric thinning concentrated volcanic activity in the tharsis region producing large shield volcanoes and extensive lava plains both central vent and plains volcanism have been active throughout martian history but the volumes of extrusion have gradually decreased with time this is consistent with a moonlike thermal history involving a lithosphere of increasing thickness with time gradually turning off the volcanism although many questions remain regarding martian volcanism the viking data have provided a remarkable detailed overview of the probable nature of the volcanic history of mars

a new crested maniraptoran dinosaur from the santana formation lower cretaceous of brazil the skull of a new and highly unusual crested dinosaur with an elongate rostrum is the first dinosaur to be named from the santana formation of ne brazil irritator challengeri gen et sp nov was most likely a maniraptoran dinosaur but its affinities to other maniraptorans remain to be established unique features for irritator include the pattern of tooth replacement a highly reduced supratemporal fenestra extreme lateral compression of the rostrum and a saggital crest comprised of the frontal and parietal bones irritator was most probably a piscivore a land link between south america and the dinosaurian faunal province of north america and asia is indicated probably via africa

chemical diversity of sands within the linear and barchan dunes of the bagnold dunes gale crater as revealed by apxs onboard curiosity

sedimentology of cold climate aeolian sandsheet deposits in the askja region of northeast iceland active aeolian sandsheets cover an area of 270 km2 in the askja region of ne iceland the sandsheet is divided into i a deflationary upwind part that is characterised by deflation lags ventifacted boulder fields and restricted aeolian sand patches in the lee of obstacles ii an accumulating central part that is characterised by continuous aeolian sand cover up to 10 m thick where three scales of aeolian ripples are evident along with larger scale forms including longitudinal zibars and iii a downwind part that is currently subject to aeolian bypass with only localised accumulation occurring in topographic hollows between basaltic lava fields trains of aeolian granule megaripples are a characteristic landform of the downwind part of the sandsheet these sinuous crested oblique bedforms attain heights of 0 35 m and downwind spacings of 6 m they are composed principally of low density pebble grade pumice clasts and other reworked volcaniclastic detritus derived from the nearby askja volcanic centre the distribution of landforms across the sandsheet reflects a regional aeolian sediment budget that is controlled by dynamic interactions between glacial ice margin fluvial aeolian and volcaniclastic processes under the influence of a distinctive climatic regime sediment supply at the upwind sandsheet margin adjacent to the dyngjujokull glacier increases during summer periods when rates of glacial ablation are at a maximum longer term controls on sediment supply rate are determined by episodes of glacier surging and retreat and by periodic eruptions of volcaniclastic debris from the askja volcanic centre the availability of sediment for aeolian transport is controlled by the level of the groundwater table the depth and continuity of the permafrost layer in the proglacial area the degree of development of armoured pebble lags and freezing of the sandsheet surface during winter months the transport capacity of the wind varies on a seasonal basis with mean wind velocities and wind gustiness reaching a maximum during winter periods both winter and summer mean wind velocities have been steadily increasing since formal records began in 1969 the suite of aeolian landforms developed within the askja region as defined by sediment texture and composition and bedform scale morphology and spatial distribution reflects a special set of controlling circumstances which mean that the askja sandsheet deposits differ significantly from those described from elsewhere

upper pleistocene and holocene stratigraphy in the kola peninsula and northern karelia n w russia marine and glacial units abstract data on litho and biostratigraphy of major sedimentary sequences and their geochronological records were compiled and summarized to describe the late pleistocene holocene marine and glacial events in the kola northern karelia region in the coastal kola peninsula and its inner part three marine units and two glacial events were identified in the upper pleistocene sequences the first marine unit ponoi beds in the regional stratigraphy can be definitely referred to the significant late pleistocene transgression known as the boreal in northern eurasia data on the kola peninsula show that the warm water boreal transgression was longer than the eemian one in western europe comprising at least mis 5e d from 130 120 to 105 100 ka bp in the white sea depression and mis 5e c earlier at least 90 ka bp in the barents sea forested environments dominated on the kola peninsula at that time the second interglacial marine unit strelna beds attributed to the subsequent belomorian transgression was deposited in relatively cold settings at the final phase of the mikulinian interglacial mis 5 about 100 to 70 80 ka bp adjacent areas were covered with open forest and tundra the third marine unit referred to the interstadial leningrad group was formed 60 40 ka bp in rather a cold marine reservoir when the environmental conditions were more severe than now the late pleistocene glacial events are correlated to the podporozhie and ostashkov groups mis 4 and 2 the podporozhian glacial unit seems to be associated with the barents kara ice sheet and its melting caused the glacioeustatic transgression in the white sea during the leningradian substage mis 3 during the late glacial and holocene a periglacial freshwater lake brackish water basin and marine reservoir successively appeared in the white sea depression successively two marine events are suggested here based on the key sedimentary sequences from the coastal isolated lake i e the late glacial transgression and the early middle holocene tapes transgression

occurrence and scale of compositional heterogeneity in martian dune fields toward understanding the effects of aeolian sorting on martian sediment compositions abstract aeolian transport and hydrodynamic sorting have been proposed to be a significant influence on martian sediment bulk compositions through laboratory experiments modeling and terrestrial analogies but to date few studies have directly examined compositional grain size relationships within sediment fields on mars thus the prevalence of hydrodynamic sorting as well as the scales at which sorting is important remain poorly understood to that end we assessed the degree and occurrence of thermophysical and compositional heterogeneity for 25 dune fields within a 42 000 000 km2 area on mars among these only four exhibit spatial heterogeneity in spectral properties and composition two of these four sites show a strong positive relationship between particle size and olivine abundance the rarity of compositional heterogeneity within dune fields in our study region 5 185 e 45 n 20 s may indicate phenocryst poor source rocks alternatively sorting within individual bedforms may be present but not at the scale of the full dune field 10 20 km compositional segregation correlated with grain size due to hydrodynamic sorting has been observed by rovers at scales much smaller than themis ground resolution 100 m pixel thus these small scales might be the operable relevant ones of hydrodynamic compositional sorting prevailing most commonly in martian dune fields

middle pleistocene age of the nome river glaciation northwestern alaska abstract during the middle pleistocene nome river glaciation of northwestern alaska glaciers covered an area an order of magnitude more extensive than during any subsequent glacial intervals the age of the nome river glaciation is constrained by laser fusion 40 ar 39 ar analyses of basaltic lava that overlies nome river drift at minnie creek central seward peninsula that average 470 000 190 000 yr 1 milligram size subsamples of the lava were dated to identify and eliminate extraneous 40ar enrichments that rendered the mean of conventional k ar dates on larger bulk samples of the same flow too old 700 000 570 000 yr while the 40 ar 39 ar analyses provide a minimum limiting age for the nome river glaciation maximum ages are provided by a provisional k ar date on a basaltic lava flow that underlies the nome river drift at nearby lave creek by paleomagnetic determinations of the drift itself at and near the type locality and by amino acid epimerization analysis of molluscan fossils from nearshore sediments of the anvilian marine transgression that underlie nome river drift on the coastal plain at nome taken together the new age data indicate that the glaciation took place between 580 000 and 280 000 yr ago the altitude of the anvilian deposits suggests that eustatic sea level during the anvilian transgression rose at least as high as and probably higher than during the last interglacial transgression by correlation with the marine oxygen isotope record the transgression probably dates to stage 11 at 410 000 yr and the nome river glaciation is younger still analyses of floor altitudes of presumed nome river cirques indicate that the nome river regional snowline depression was at least twice that of the maximum late wisconsin the cause of the enhanced snowline lowering appears to be related to greater availability of moisture in northwestern alaska during the middle pleistocene

the volcanic history of central elysium planitia implications for martian magmatism abstract central elysium planitia cep is located south of elysium mons back to the era of the viking orbiters clues accumulated in favor of recent volcanism in relation with ground water release and the formation of long sub parallel fissures four aqueous flood channel systems emanate from linear fissures recent eruptions of low viscosity lavas originate from these fissures and from low shield volcanoes the objective of this paper is to constrain the volcanic history of this region and to determine the chronological relationships with fluvial erosional processes new observations e g new shield volcanoes and one new fluvial event are summarized on a context map thirty five surfaces have been dated from the count of about 15 000 impact craters ages have been cross checked with relative stratigraphy when possible a probabilistic approach has been introduced to compare similar ages and define periods of volcanic activity our results confirm that some volcanic features are extremely recent 2 my active periods are found at 2 5 3 my 4 3 my 13 5 16 2 my 19 my 21 32 my 58 my 71 my 85 95 my 134 my 173 my and 234 my not excluding the possibility that some of the gaps would be filled with additional crater counts the volcanic activity thus extended for at least the last 250 my the lava volumes have been estimated from the topographic modeling of the floor of depressions filled up by volcanic products including the volumes of several large crater cavities buried under lavas 20 of the total volume our new estimation of the total lava volume is 1 5 0 2 10 5 km 3 this value corresponds to an average thickness of one hundred meters of lavas for the young volcanic plain as a consequence the total eruption rate at cep defined as the total volume of lava divided by the time of emplacement 1 4 10 2 1 8 10 2 m 3 s is lower than values typically estimated for terrestrial hot spots or large igneous provinces suggesting longer inactive periods the concept of mantle plumes responsible for terrestrial flood volcanism may not be applicable to the case of cep and the mechanism proposed in schumacher and dreuer 2007 offers a plausible alternative to explain our observations

dinosaurs and other fossil vertebrates from fluvial deposits in the lower cretaceous of southern tunisia remains of dinosaurs and other vertebrates sharks bony fishes coelacanths turtles crocodilians pterosaurs are reported from the chenini formation of the tataouine region in southern tunisia the formation is part of the continental intercalaire a succession of continental deposits of early to late cretaceous age distributed over the whole of north africa and the sahara it consists of bar and channel deposits of broad rivers that flowed nnw from the mid sahara region towards the southern shore of tethys dinosaur bearing units in the continental intercalaire have been dated to the hauterivian to cenomanian and the chenini formation is possibly albian in age dinosaur fossils include abundant teeth of the theropods carcharodontosaurus and spinosaurus as well as postcranial elements of theropods and a medium sized sauropod a tooth of an ornithocheirid is the first report of a pterosaur from the region the dinosaur bones and teeth were transported some distance and deposited in a channel lag associated with less damaged locally derived material such as fern fronds coprolites fish teeth and scales and crocodilian scutes

olivine and pyroxene diversity in the crust of mars datafromthe observatoire pour la mineralogie l9eau les glaces et l9activite omega on the mars express spacecraft identify the distinct mafic rock forming minerals olivine low calcium pyroxene lcp and high calcium pyroxene hcp on the surface of mars olivine and hcp rich regions are found in deposits that span the age range of geologic units however lcp rich regions are found only in the ancient noachian aged units which suggests that melts for these deposits were derived from a mantle depleted in aluminum and calcium extended dark regions in the northern plains exhibit no evidence of strong mafic absorptions or absorptions due to hydrated materials

gusev photometric variability as seen from orbit by hrsc mars express minnaert and two term phase function hapke models are used to describe the photometric properties of the martian surface using hrsc high resolution stereo camera multi angular observations acquired along the ongoing mars express mission these observations can be pieced together to derive integrated phase functions over a wide range of phase angles the photometric diversity at 675 nm as seen from orbit of the martian surface properties across gusev is depicted with seven units three photometric units widespread across the flanks of apollinaris patera flank and the floor of gusev crater are identified as having high single scattering albedo with rather forward scattering properties low to intermediate macroscopic roughness and porous or not compacted powdered surface state as indicated by the opposition parameters another unit has the highest single scattering albedo the smoothest surface in terms of macroscopic roughness associated with an extremely forward scattering behavior the opposition parameters are consistent with the presence of transparent particles in the surface powder layer the distribution of this unit appears quite intermittent across the crater and does not seem to indicate any relationship with a given morphological structure it may correspond to sparse areas where the structure of the surface dust layer is the most preserved the most pronounced photometric changes are observed in three units associated with the low albedo features corresponding to dark wind streaks these units have a low single scattering albedo are the most backscattering surfaces across gusev have a high surface roughness and present variable surface states as shown by the opposition parameters estimates consistent with the occurrence of large grains organized in more or less packed layers clear differences are seen among these units in terms of opposition effect while one exhibits typical characteristics for the opposition effect another appears more unusual in terms of lobe width and the third suggests the occurrence of a packed compressed narrow size distribution powder surface the opposition effect thus appears to play a significant role suggesting that the surface state optical properties across gusev are strongly influenced by the porosity and packing characteristics or grain size distribution of the upper layer of the martian soil the mapping aspect of the investigation is quite useful to get a better sense of the meaning of the observed photometric variations indeed the hapke modeling suggests that surface organization surface roughness packing state is more important than the simple physical characterization of the intrinsic optical properties of the constitutive particles given the overall spatial patterns derived from the photometric analysis the variations at least for the western and central part of gusev crater are likely partly driven by the prevailing wind regimes considered to be oriented north northwest south southeast and disturbing the very upper surface layer the present photometric results agree with independent investigations based on thermal inertia reflectance spectroscopy in situ photometric and microscopic imaging and support the idea of a thin layer of fine grained dust being stripped off in the low albedo units to reveal a dark basaltic substrate comprising coarse grained materials

a study of low albedo deposits within amazonis planitia craters evidence for locally derived ultramafic to mafic materials 1 we studied low albedo deposits in the floors of craters within the amazonis planitia region using infrared data from mars global surveyor thermal emission spectrometer tes and mars odyssey thermal emission imaging system themis high resolution visible images from the mars orbiter camera and themis and topographic data from the mars orbiter laser altimeter these deposits are found within subdued to sharp rimmed craters that impacted into thick basaltic lava flows from olympus mons these lava flows flooded the region and were subsequently eroded by aeolian processes tes spectral modeling of the low albedo deposits reveals a mineralogy that is dominated by mafic minerals olivine pyroxene with a derived bulk chemistry that ranges from ultramafic to mafic 40 52 wt sio2 in composition these bulk compositions are comparable to some martian lithologies but represent some of the lowest silica contents identified on mars the compositional range could be produced by either primary igneous processes or subsequent alteration by aeolian processes the spatial distribution of the compositions reveals weak to absent groupings and does not distinguish between the igneous or aeolian scenarios in some craters possible local sources have been identified within the crater walls floors and interiors local sources may be present in additional craters but obscured by dust no regional sources were identified within a reasonable distance in terms of sand transport but may also be obscured by dust therefore the low albedo deposits probably resulted from aeolian erosion of local intracrater basaltic materials that were subsequently redistributed within the floors of these craters

recent flood lavas in the elysium region of mars abstract a vast area of smooth plains in southeastern elysium here referred to as the cerberus formation is interpreted to be of volcanic origin surface morphology lobate edges of the unit the identification of vents low shields and the embayment relation of the unit with adjacent older units all suggest a volcanic origin the plains were formed by the eruption of low viscosity lavas that filled a topographic depression in southeast elysium and then flowed into western amazonis planitia flow into western amazonis was facilitated by a series of channels carved by an earlier fluvial episode which were exploited by lavas as they moved down slope crater frequencies and stratigraphic relations indicate that the unit is very young upper amazonian the presence of such young flood lavas indicates 1 late in martian history large scale eruptions of low viscosity lava was still possible b sufficient heat remained in the mantle to mobilize large quantities of magma and c flood volcanism either continued or resumed in elysium after activity of the large central volcanoes had ceased each of these points are important considerations in understanding the martian thermal and volcanic history

thermoluminescence dating of the holsteinian marine formation of herzeele northern france thermoluminescence dating of potassium feldspar coarse grains from the fossiliferous holsteinian marine formation of herzeele at the southern limit of the north sea basin yields a minimum age of 228 30 ka a tentative correction for the long term fading of the tl signal in potassium feldspar is proposed assuming a lifetime of 711 ka this correction would yield a preliminary age estimate of 271 36 ka these results support a minimum oxygen isotope stage 7 age but do not preclude at this stage of our research a possible correlation with late oxygen isotope stage 9 these results are in agreement within the error of the method with independent absolute dates u th and esr obtained on in situ marine shells which range from 225 ka to 348 ka this study provides evidence of the reliability of tl age estimates on potassium feldspar coarse grains from shallow marine sediments older than the last interglacial

evidence for a middle pleistocene glaciation of mis 8 age in the southern north sea abstract in the cores of borehole 89 2 situated at 54 00 01 n and 5 00 04 e about 70 km north of the frisian islands in the southern north sea two diamictons levels are found at 70 and 100 m below sea floor i e 110 and 140 below present sea level respectively both diamictons appear to be older than saalian mis 6 in contrast to earlier interpretations the upper diamicton is overlain by about 20 m of shallow marine sands followed by a chaotic alternation of fine grained clay rich eemian mis 5e sediments and sands deposited in a glacially excavated basin it was originally assumed that this diamicton was saalian mis 6 in age and lined the base of the basin seismic lines crossing the borehole location however show that the upper diamicton is truncated by the basin and consequently must be older than saalian this is corroborated by new investigations on the saalian eemian transition in the netherlands and new data on the age of the molluscs and foraminifera in the sands directly overlying the upper diamicton the age data based on measurements of the isoleucine epimerisation of mollusc shells and foraminiferal tests favour an mis 8 age

new views of mars eolian activity materials and surface properties three vignettes from the mars global surveyor mars orbiter camera prior to the mars global surveyor mgs mission a very general view had emerged in which martian surface materials were seen as consisting of a mixture of bright dust dark sand and rocks the configuration of these materials and the winds that transport and deposit sand and dust have been thought to be directly linked to the albedo patterns that have been observed on mars for centuries high spatial resolution images 1 4 20 m pixel obtained by the mgs mars orbiter camera moc between september 15 1997 and july 4 1999 provide new information about the physical nature of the windblown material on the martian surface and show that the pre mgs view was much too simple in addition to bright dust and dark sand moc images show evidence of bright sediment that can be transported by saltation e g sand and dark material that can be transported in suspension e g silt new views of eolian wind streaks in daedalia planum show that part of this region thought to be mantled by bright dust based upon viking and mariner observations is instead covered by a thin veneer of bright windblown sand moc images of sinus sabaeus and parts of syrtis major two regions thought to be sandy based upon viking era observations exhibit thick mantles that are inferred to consist of fine grained sediment deposited from eolian suspension low albedo wind streaks in western arabia terra are also dark mantles and their association with eroded crater floors and megaripples dunes on these floors suggest that these particular wind streaks are deposits of silt sized material that was only briefly suspended before settling to the surface moc images also show evidence that some eolian dunes are active on mars today i e in 1998 and 1999 the evidence for activity is largely based upon wind and avalanche induced streaks superposed on or eroded into seasonal frost on high latitude dune fields moc images show that some other dunes are inactive but the albedo of dunes relative to surrounding terrain is not a good indicator of dune activity because some inactive dunes are not mantled by dust inactive dunes are best identified by superposed features such as impact craters landslide deposits and yardangs

chemical composition of martian soil and rocks complex mixing and sedimentary transport chemical compositions of martian soil and rocks indicate complex mixing relationships mixing of rock and soil clearly takes place and explains some of the chemical variation because sulfur chlorine magnesium and perhaps iron are positively correlated due to their control from a secondary sedimentary mineralogy e g mg and possibly fesulfate fe oxides that is present within the soils certain deviations from simple soil rock mixing are consistent with mineralogical fractionation of detrital iron and titanium oxides during sedimentary transport

apxs derived chemistry of the bagnold dune sands comparisons with gale crater soils and the global martian average we present apxs data for the active bagnold dune field within the gale impact crater msl mission we derive an apxs based average basaltic soil abs composition for mars based on past and recent data from the msl and mer missions this represents an update to the taylor and mclennan 2009 average martian soil and facilitates comparison across martian datasets the active bagnold dune field is compositionally distinct from the abs with elevated mg ni and fe suggesting mafic mineral enrichment and uniformly low levels of s cl and zn indicating only a minimal dust component a relationship between decreasing grain size and increasing felsic content is revealed the bagnold sands possess the lowest s cl of all martian unconsolidated materials gale soils exhibit relatively uniform major element compositions similar to meridiani planum and gusev crater basaltic soils mer missions however they show minor enrichments in k cr mn and fe which may signify a local contribution the lithified eolian stimson formation within the gale impact crater is compositionally similar to the abs and bagnold sands which provide a modern analogue for these ancient eolian deposits compilation of apxs derived soil data reveals a generally homogenous global composition for martian soils but one that can be locally modified due to past or extant geologic processes that are limited in both space and time

compositional variations in sands of the bagnold dunes gale crater mars from visible shortwave infrared spectroscopy and comparison with ground truth from the curiosity rover during its ascent up mount sharp the mars science laboratory curiosity rover traversed the bagnold dune field we model sand modal mineralogy and grain size at four locations near the rover traverse using orbital shortwave infrared single scattering albedo spectra and a markov chain monte carlo implementation of hapke s radiative transfer theory to fully constrain uncertainties and permitted solutions these predictions evaluated against in situ measurements at one site from the curiosity rover show that x ray diffraction measured mineralogy of the basaltic sands is within the 95 confidence interval of model predictions however predictions are relatively insensitive to grain size and are nonunique especially when modeling the composition of minerals with solid solutions we find an overall basaltic mineralogy and show subtle spatial variations in composition in and around the bagnold dunes consistent with a mafic enrichment of sands with cumulative aeolian transport distance by sorting of olivine pyroxene and plagioclase grains furthermore the large variations in fe and mg abundances 20 wt at the bagnold dunes suggest that compositional variability may be enhanced by local mixing of well sorted sand with proximal sand sources our estimates demonstrate a method for orbital quantification of composition with rigorous uncertainty determination and provide key constraints for interpreting in situ measurements of compositional variability within martian aeolian sandstones

skeletal remains of a small theropod dinosaur with associated soft structures from the lower cretaceous santana formation of northeastern brazil associated well preserved uncrushed skeletal remains comprising the pelvic girdle partial sacrum both femora and parts of the right tibia and fibula from the romualdo member of the lower cretaceous santana formation of northeastern brazil record the presence of a previously unknown coelurosaurian theropod dinosaur in that formation the pelvic girdle is noteworthy for the bilaterally asymmetrical development of various bony features the specimen also preserves a segment of lithified intestinal tract while still in the matrix the fossil preserved a vacuity behind the pubic apron that may indicate the existence of a postpubic air sac

aminostratigraphic relations and age of quaternary deposits northern espanola basin new mexico abstract amino acid ratios of gastropods provide a useful basis for correlation and approximate dating of middle to late quaternary fluvial deposits from the northern espanola basin new mexico sparsely fossiliferous slackwater deposits in the rio chama rio grande floodplain were buried episodically by piedmont alluvium during periods of climatic change as the axial river system cut down 120 m during the past 620 000 yr alloisoleucine isoleucine alle ile ratios in the total hydrolysate and free fraction of amino acids in succinea and vallonia are strongly correlated with elevation ratios in succinea range from 0 01 to 0 79 in the total hydrolysate and from 0 00 to 1 15 in the free fraction for deposits that range in age from modern to 620 000 yr old amino acid ratios are tightly clustered for deposits that contain the 620 000 yr old lava creek b tephra layer demonstrating their utility for correlation and providing a calibration point for a local dating curve two 14c ages from younger deposits and limiting ages for erosion surfaces that lie above gastropod bearing units tend to support the validity of much of the curve combining the dating curve with the geologic constraints suggests that aggradation events separated by episodes of net incision occurred at about 620 000 310 000 70 000 170 000 40 000 95 000 15 000 yr ago after 19 000 yr ago and during two minor periods between 80 000 and 25 000 yr ago

debris flows over sand dunes on mars evidence for liquid water 1 this study focuses on the formation and physical properties of the gullies observed over large martian dunes especially those of the russell crater 54 s 347 w geomorphic features like sinuosities and connections of the channels show that gullies over dunes involve flows with a significant proportion of liquid the occurrence of levees implies that these flows are debris flows with a yield strength characteristics of bingham plastic materials we apply terrestrial methods to estimate viscosity and velocity of these flows from levee size and sinuosities we obtain average velocities in the range of 1 to 7 m s 1 and apparent viscosities of 2 8 to 46 000 pa s with an average at 740 pa s compared with the 0 001 pa s of pure water these viscosities and velocities are in the range of terrestrial debris flows with a proportion of 10 to 40 of h2o these properties are typical of water holding debris flows but not of pure water surface runoff or co2 driven flows the debris flows over dunes are oriented on south facing slopes like other recent gullies meltwater from ground ice formed during a recent period of high obliquity is the more likely explanation for the formation of such flows over dunes

the potassic sedimentary rocks in gale crater mars as seen by chemcam on board curiosity key points mean k2o abundance in sedimentary rocks 5 times higher than that of the average martian crust presence of alkali feldspars and k phyllosilicates in basaltic sedimentary rocks along the traverse the k bearing minerals likely have a detrital origin

assessing martian bedrock mineralogy through windows in the dust using near infrared and thermal infrared remote sensing abstract much of mars surface is mantled by bright dust which masks the spectral features used to interpret the mineralogy of the underlying bedrock despite the wealth of near infrared nir and thermal infrared tir data returned from orbiting spacecraft in recent decades the detailed bedrock composition of approximately half of the martian surface remains relatively unknown due to dust cover to address this issue and to help gain a better understanding of the bedrock mineralogy in dusty regions dust cover index results from the mars global surveyor thermal emission spectrometer tes and analysis of images from the mars reconnaissance orbiter mars color imager marci were used to identify 63 small localized areas within the classical bright dusty regions of arabia terra elysium planitia and tharsis montes as potential windows through the dust that is areas where the dust cover is thin enough to permit infrared remote sensing of the underlying materials the mineralogy of each candidate window was inferred using spectra from the mars express observatoire pour la mineralogie l eau les glaces et l activite omega nir spectrometer and where possible tes twelve areas of interest returned spectra that are consistent with mineral species expected to be present at the regional scale such as high and low calcium pyroxene olivine and iron bearing glass distribution maps were created using previously defined index parameters for each species present within an area high quality tes spectra if present within an area of interest were deconvolved to estimate modal mineralogy and to support nir interpretations omega data from arabia terra and elysium planitia are largely similar and indicate the presence of high calcium pyroxene with significant contributions of glass and olivine while tes data suggest an intermediate between the established compositions of the southern highlands and syrtis major limited data from tharsis are consistent with low calcium pyroxene mixed with lesser amounts of glass and high calcium pyroxene tes data from southern tharsis correlate well with the previously inferred compositions of the aonium and mare sirenum highlands immediately to the south of particular note is the detection of iron bearing glass as a significant component of all three analyzed regions especially in tharsis overall the underlying compositions of the classically dust covered regions of mars appear consistent with the compositions of adjacent and other low albedo not dust covered regions of the planet identified in previous studies with the noted contribution from iron bearing glass

mineralogy of recent volcanic plains in the tharsis region mars and implications for platy ridged flow composition volcanism on mars occurred until recently but the mineralogy of recent lava plains is poorly known because few regions display fresh outcrops devoid of dust using visible and near infrared data of the mars express probe two new volcanic plains in noctis labyrinthus have been identified and the existence of a volcanic plain on the floor of echus chasma has been confirmed crater retention ages estimated for these three plains range between 50 and 100 my corresponding to the late amazonian these plains represent an excellent opportunity to constrain the mineralogy of recent volcanic rocks results show that basaltic compositions with plagioclase and high calcium pyroxene are predominant the low olivine proportion suggests that the apparent fluidity of these flat plains is not related to magmas being ultramafic in addition a platy ridged texture is observed in two of the studied regions our study shows for the first time that this texture is associated with volcanic rocks and that these rocks are of typical basaltic mineralogy finally these volcanic plains are located more than 1000 km east of previously known late amazonian volcanic centers of the tharsis region an observation to be taken into account when considering models of recent volcanism on mars c 2009 elsevier bm all rights reserved

amino acid geochronology its impact on our understanding of the quaternary stratigraphy of the british isles this review aims to act as a brief primer to amino acid racemization and protein breakdown as well as to document the major applications and results of amino acid dating on british quaternary sediments amino acid results from fossil shells have had far reaching effects in developing our current understanding of british quaternary stratigraphy and its links to continental europe and the marine record to appreciate the potential for amino acid geochronology the technique s limitations and recent developments are discussed as well as the future of the field copyright 2009 john wiley sons ltd

segregation of olivine grains in volcanic sands in iceland and implications for mars abstract basaltic sands cover several plains in volcanic regions on earth and dominate the aeolian sediments on mars but basaltic sands are not as well characterized as felsic sands the lambahraun sandy lava plain in iceland was chosen as a martian analog to study the physical sorting of basaltic sands the strong winds affecting the plain and its young age

amino acid geochronology applied to the correlation and dating of central european loess deposits abstract numerous localities in the czech republic slovakia and austria have been sampled for fossil gastropod shells for the purpose of an aminostratigraphic evaluation of loess sequences in all three regions alloisoleucine isoleucine aile ile ratios are observed to be significantly higher in shells from loess deposited during the penultimate glacial period cycle c relative to samples from loess of the last glaciation cycle b the difference in aile ile ratio reflects both difference in age of the samples plus the impact on the older samples of the relatively high effective temperature of the last interglacial period amino acid data support the previous correlation suggested between pk ii iii in the czech republic and slovakia and the stillfried a in austria samples have also been recovered from older loess units and previously published correlations within the czech and slovak republics are tested aiie ile ratios appear to distinguish between samples from loess of the last four glacial cycles beyond cycle e 18o stages 10 and 11 the increase in alle ile ratio is relatively small from cycle to cycle in addition shells tend to be poorly preserved and are absent at many localities nevertheless amino acid geochronology offers a means of resolving ages of loess units in the critical time period that is beyond the range of radiocarbon and thermoluminescence methods but post dates the brunhes matuyama paleomagnetic reversal

sedimentary history of za hajovnou cave moravia czech republic a unique middle pleistocene palaeontological site za hajovnou cave in the javoricko karst moravia czech republic has a rich record of middle pleistocene typical holsteinian flora and fauna dominated by bear ursus deningeri sedimentological geochemical mineralogical geophysical palynological and zoopalaeontological analyses of the sediments along with u th dating of flowstones place the deposits into a numerical timeframe the cave origin dates to a period before the mid miocene badenian transgression the oldest fluvial deposits are lower pleistocene spanning the brunhes matuyama boundary the later terrestrial deposits range from middle pleistocene to holocene the most important result of u th dating is that the main holsteinian senso lato fossil bed can be correlated with mis 9 the lower fossil bed is probably mis 11 and the upper fossil bed mis 5e this represents one of the still relatively few numerically dated holsteinian sites contradicts the global chronostratigraphical correlation table that places the holsteinian only in mis 11 and supports the concept that the holsteinian is not a single unit and likely not confined to a single interglacial c 2013 elsevier ltd and inqua all rights reserved

a systematic mapping procedure based on the modified gaussian model to characterize magmatic units from olivine pyroxenes mixtures application to the syrtis major volcanic shield on mars clenet et al 2011 have developed an adapted version of the modified gaussian model mgm the improvements allow the characterization of spectra of olivine pyroxene s mixtures addressing both modal composition and individual minerals chemical composition this version of mgm is fully automated and operational with large amounts of hyperspectral imaging data two natural cases are considered the first one is the sumail massif in the oman ophiolite earth based on our approach applied to hymap data two contrasted lithologic units are mapped the mantle which is harzburgite dominated and the crust made of gabbros and clinopyroxene rich cumulates with spectral variations interpreted in terms of pyroxenes chemical compositions once this new mgm mapping approach has been validated on a controlled natural situation we map the distribution of mafic assemblages across the syrtis major volcano on mars using a visible and near infrared vnir short wave infrared swir observatoire pour la mineralogie l eau les glaces et l activite omega mars express mex mosaic our results are in agreement with previous work but olivine appears to be more abundant than previously estimated in the central part of the volcanic edifice especially in ternary mafic assemblages augite olivine enstatite based on these results we propose a possible scenario for the igneous and thus thermal evolution of the syrtis major region surrounding terrains have formed first and local heterogeneity can be observed between northern and southern areas of the noachian crust we also observe variations in the mineral assemblages within syrtis major lavas which can be interpreted in terms of differentiation from a common parent melt and or of a progressive evolution of the mantle source composition and temperature key points mgm systematic mapping on syrtis major to characterize mafic minerals mixtures olivine and pyroxenes mixture is detected in the central lavas of the volcano pyroxenes have chemical compositions spanning the enstatite augite range

till stratigraphy and glacial history of the vestfold hills area east antarctica abstract the formation properties and stratigraphy of glacigenic deposits were studied at the marginal zone of the east antarctic ice sheet during the 1988 1989 australian national antarctic research expedition anare samples 132 were collected for granulometric geochemical heavy mineral and various dating analysis fabric analyses 27 were performed from glacial till and debris rich basal ice three test pits were excavated through frozen sediments to solid bedrock at a depth of 4 2 m the whole ice free area of 410 km2 was studied by stereo interpretation of aerial photographs and reconnaissance field survey a small outlet glacier the sorsdal glacier flows gently to the sea at the southern part of the vestfold hills area its terminus is floating the glacier was previously much larger and a majority of the moraine ridges in the vestfold hills area are probably lateral moraines of its former extensions radial and lateral flow of the glacier was observed from till fabric and striation data the present ice flow pattern and debris fabric in the glacier sole is similar to the one observed from till fabric and striations tills deposited by earlier phases of the sorsdal glacier cover an interglacial deposit of shelly gravel near the australian davis station shelly gravel represents clearly an ice free period when the climate was warmer and sea level higher than at present and this stage is named the davis interglacial according to the thermoluminescence tl datings and amino acid analyses of the shelly gravel deposits it seems that the davis interglacial is over 300 000 or over 1 000 000 years old the glacial stratigraphy of the vestfold hills shows at least two similar pleistocene outlet glacier floodings during which the sorsdal glacier had drained the vast ice masses of the continental ice sheet beyond the vestfold hills antarctic oasis

the chemical index of alteration cia as a proxy for climate change during glacial interglacial transitions in earth history abstract the glacial interglacial transitions of ice ages are associated with large rapid changes in climate which potentially can be reconstructed from stratigraphic profiles of the chemical index of alteration cia here we present a case study based on high resolution cia profiles of neoproterozoic glacial deposits from south china paleolatitude 30 n as a record of the climate transition at the termination of the sturtian glaciation 663 ma drillcore zk2115 gaodi deposit exhibits a progressive upsection increase in mean cia over a 50 m interval from 58 range 52 65 note all ranges are given as 16th 84th percentiles in the synglacial upper tiesi ao formation to 67 range 64 69 in the deglacial basal datangpo formation cap carbonates and to 68 range 66 70 in the postglacial datangpo formation black shales a coeval section from the lijiawan deposit also exhibits an increasing cia trend upsection within shallow water mn carbonate facies these cia patterns show no relationship to lithology and are interpreted to reflect climatic warming and intensified chemical weathering during the sturtian deglaciation similar large increases in postglacial cia values are seen in paleoproterozoic and late paleozoic successions and at least moderate increases in cia values are recorded during warm stages of the late quaternary e g the bolling allerod and holocene relative to the cold stages e g the last glacial maximum and younger dryas the rapidity of cia changes in quaternary systems 1 to 10 kyr suggests that weathering intensity may have changed at similarly rapid rates in more poorly dated deep time glacial successions with potential implications for snowball versus slushball models of cryogenian glaciations these examples show that cia can be a robust proxy for climate changes i e enhanced chemical weathering intensity during glacial interglacial transitions of both ancient and recent ice ages

notes on fossil remains from the early cretaceous lohan cura formation neuquen province argentina inthiscontribution wedescribeanassociationoffossilremainscollectedinthelocalityofcerrodelosleones approximately8kmsouthwestof the town of picun leufu neuquen province argentina from different levels of the albian cullin grande member lohan cura formation the fossils include pelecypodan neocorbicula dinosauriorum neocorbicula pehuenchensis and genus indet and gastropodan physa wichmanni molluscs amesoeucrocodylian possiblepterosaurs theropods andsauropods the sedimentaryenvironment at cerro delos leones ischaracterized by fluvial deposits corresponding to a sandy meandering fluvial system the most fossiliferous levels located in the lower part of the exposed sequence were developed in a distal flood plain and flood basin areas sedimentological and paleopedological features suggest semi arid conditions during the deposition of the cullin grande member despite the fragmentary nature of the specimens described here the new information provided from the albian assemblages of the lohan cura formation at the cerro de los leones locality provides a broader panorama of the composition of terrestrial faunas during the early cretaceous in patagonia 2006 international association for gondwana research published by elsevier b v all rights reserved

reflection of scandinavian ice sheet fluctuations in norwegian sea sediments during the past 150 000 years the record of glacier fluctuations in western scandinavia as reconstructed from continental data has been correlated with records of ice rafted detritus ird from well dated sediment cores from the norwegian sea covering the past 150 000 yr b p the input of ird into the ocean is used as a proxy for ice sheet advances onto the shelf and thus for the calibration of a glaciation curve the marine results generally support land based reconstructions of glacier fluctuations and improve the time control on glacial advances the saalian ice sheet decayed very rapidly approximately 125 000 yr b p in the early weichselian a minor but significant ird maximum indicates the presence of icebergs in isotope substage 5b especially between 95 000 and 83 000 yr b p reduced amounts of calcareous nannofossils indicate that surface waters were influenced by meltwater discharges during isotope substages 5d and 5b an extensive build up of inland ice began again during isotope stage 4 but maximum glaciation was reached only in early stage 3 58 000 53 000 yr b p marine sediments have minimum carbonate content indicating strong dilution by lithogenic ice rafted material generally the ird accumulation rate was considerably higher in stages 4 2 than in stage 5 a marked peak in ird accumulation rates from 47 000 to 43 000 yr b p correlates well with a second middle weichselian ice sheet advance dated by the laschamp olby paleomagnetic event minimum ice extent during the alesund interstade 38 500 32 500 yr b p and several glacial oscillations during the late weichselian are also seen in the ird record of several late weichselian glacial oscillations on the shelf at least four correspond to the north atlantic heinrich events ice sheet behavior was either coupled or linked by external forcing during these events whereas internal ice sheet mechanisms may account for the noncoherent fluctuations

aminostratigraphy of european marine interglacial deposits molluscan fossils collected from shallow water marine sediment across nw europe and nearby arctic regions have been analysed for the extent of isoleucine epimerization dl ratio in indigenous protein residues the dl ratios confirm that essentially all classical eemian sites from nw europe are of the same age and are correlative with the type locality near amersfoort in the netherlands shells from interglacial marine sediment beneath the type weichselian till in poland also correlate with the type eemian site dl ratios in holsteinian marine shells 0 29 are substantially higher than in their eemian counterparts 0 17 late cromerian shells yield even higher ratios 0 46 dl ratios in late glacial shells 0 06 and middle weichselian shells 0 09 permit differentiation from modern 0 01 and last interglacial material based on the position of the matuyama brunhes boundary and the differences in dl ratios the eemian must correlate with isotope substage 5e whereas the holsteinian is most likely substage 7c possibly stage 9 but certainly younger than stage 11 intra saalian warm periods may be terrestrial equivalents of the younger substages of stage 7 extensive pre eemian marine sediments along the sw coast of denmark previously correlated with the holsteinian are shown to be of late cromerian age the underlying till there is the first widespread evidence of a pre elsterian till in nw europe dl ratios in molluscs from last interglacial sites along the arctic coast of the ussr the arctic islands and eastern greenland are substantially lower than in their european counterparts due to their low thermal histories the combined mid and high latitude data are used to develop a predictive model for the expected dl ratio in any of several moderate epimerization rate taxa for last interglacial sites with mean temperatures between 20 and 15 c not all sites could be unambiguously assigned to an established interglacial the fjosanger norway and margareteberg sweden sites previously thought to be eemian yield dl ratios higher than in secure nearby eemian material it is yet unresolved whether these are aberrant sites or if they predate the last interglacial in situ shoreline deposits encountered in borings in sw belgium and in exposures on the belgium coastal plain contain molluscs that yield dl ratios intermediate between secure eemian and late weichselian ratios raising the possibility that a late stage 5 high sea level event attained near modern levels in the southern north sea basin resolution of these uncertainties is the focus of future work

evidence for locally derived ultramafic intracrater materials in amazonis planitia mars 1 we studied a dark intracrater feature in amazonis planitia using visible thermal and spectral data from the mars global surveyor mgs thermal emission spectrometer tes mgs mars orbiter camera moc and 2001 mars odyssey thermal emission imaging system ody themis instruments visible and thermal data indicate that there are heterogeneities within the dark feature at meter to kilometer scales and suggest that it represents eroded terrain containing inactive ripple like bed forms possibly armored or indurated as well as loose possibly actively saltating sediment in addition part of the dark intracrater material may be covered with dust either as an optically thin few microns thick layer or as thicker discontinuous patches the thermal properties of the dark material are consistent with a mixture of sand rock and bedrock whereas the rest of the crater floor has thermal characteristics of fine 35 m particulates spectral data indicate that the crater floor is covered by a layer of dust that is spectrally and compositionally similar to the globally homogenized surface dust in other high albedo regions on mars the mineralogy of the dark materials is mafic dominated modally by pyroxene and olivine however unlike other lithologies common in low albedo regions i e surface types i and ii its derived bulk chemistry indicates that it is an ultramafic lithology with the lowest silica content detected on mars to date sheet silicates and glasses are not identified above detection limits and as such the materials do not display evidence for significant chemical weathering the geomorphology and visible distribution of the dark intracrater materials combined with the lack of an obvious source in the region outside the crater suggest they are the product of erosion of a local source

the last glacial maximum on spitsbergen svalbard most scientists have concluded previously that the west coast of spitsbergen svalbard remained ice free during the late weichselian between 25 000 and 10 000 yr b p we conclude that the glaciation was more extensive terraces that were postulated to have been ice free are covered by a thin late weichselian till sudden drop in the marine limit and basal radiocarbon dates of raised glaciomarine sediments demonstrates that the glaciers in the main fjords isfjorden and van mijenfjorden terminated west outside of the fjord mouths basal radiocarbon dates from glaciomarine clay above till in cores from the continental shelf west of spitsbergen yielded ages of about 12 500 yr b p from which we conclude that the ice extended to the shelf edge based on the extent of amino acid diagenesis in radiocarbon dated molluscs the duration of the maximum extension of the late weichselian glaciation was short certainly less than 10 000 years during the ice free period preceding that glaciation at least back to 40 000 yr b p the glaciers on svalbard were not significantly larger than at present as shown by marine deposits close to the glacier snouts many radiocarbon dates place deglaciation of the outer coast at about 12 500 yr b p at about 10 000 yr b p the rest of the archipelago rapidly became ice free

late pleistocene stratigraphy according to the sediment sequence from eastern kola peninsula ponoi river valley north western russia abstract the sedimentary sequence from the local stratotype section of the mikulinian mis 5 marine deposits at the ponoi river valley easternmost kola peninsula north western russia has been investigated to define the geological and numerical ages and chronostratigraphic position of a marine unit identified previously as a lithostratigraphic unit of the lower part of the mikulinian and named the ponoi beds in the regional kola stratigraphic scheme the new data indicate that the ponoi beds has two part sedimentary succession which was formed during two successive interglacial boreal and belomorian marine transgressions in the mikulinian mis 5 time the lower clay part of this succession accumulated in the interglacial marine basin until c 96 ka under favourable environmental and climatic conditions the upper sandy part of this lithostratigraphic formation also previously attributed to the ponoi beds accumulated in the late mikulinian marine basin about 70 ka ago under relatively cold and damp climate conditions in accordance with our new data obtained in this study it has to be attributed to another marine unit referred to as the strelna beds formed during the second belomorian interglacial marine transgression also during the mikulinian time formerly the strelna beds was correlated with the podporozhian mis 4 horizon in the current regional kola stratigraphic scheme both the ponoi and strelna beds marine sediments have to be related and linked with the marine basin during mis 5 these marine units have to be correlated with the mikulinian mis 5 horizon

mars surface diversity as revealed by the omega mars express observations the observatoire pour la mineralogie l eau les glaces et l activite omega investigation on board the european space agency mars express mission is mapping the surface composition of mars at a 0 3 to 5 kilometer resolution by means of visible near infrared hyperspectral reflectance imagery the data acquired during the first 9 months of the mission already reveal a diverse and complex surface mineralogy offering key insights into the evolution of mars omega has identified and mapped mafic iron bearing silicates of both the northern and southern crust localized concentrations of hydrated phyllosilicates and sulfates but no carbonates and ices and frosts with a water ice composition of the north polar perennial cap as for the south cap covered by a thin carbon dioxide ice veneer

new data on the pleistocene of mallorca abstract stratigraphic geomorphologic and isoleucine epimerization studies at 15 sites in mallorca define four aminozones a c e and f g of increasing age that are related to transgressive regressive marine cycles from the holocene to the mid pleistocene calibration of aminozone e glycymeris aile ile mean from all sites 0 41 0 03 n 38 is provided by a 129 7 ka u series coral age on cladocora caespitosa from son grauet of the younger aminozones a relates to the holocene transgression and aminozone c to a mid to late isotopic stage 5 event 90 15 ka revealed only by supralittoral eolianites assigning an age to the older poorly resolved aminozones f and g called f g in this case is uncertain without supporting radiometric data but an age of 180 ka can be assigned to these aminozone s f g based on a kinetic model and other examples in the mediterranean several deposits previously dated u series molluscs between 75 and 300 ka appear to belong to the last interglacial complex stage 5 and aminozone e a proposed revision of the positive sea level history of mallorca shows multiple minor oscillations during the major last interglacial cycle stage 5 and two mid pleistocene sea levels one lower than present and the other at about 14 m a s l

isotope stage 5 130 74 ka in greenland a review abstract marine and glacigene deposits dated with varying degrees of certainty to isotope stage 5 130 74 ka are exposed in coastal cliffs in 18 areas and localities in northern and eastern greenland dating methods include thermoluminescence tl u th methods and correlation with the deep sea record amino acid parameters are used for correlation between localities deposits from the last interglaciation isotope substage 5e are rare and have been found only at three localities in both west and east greenland their mollusc and foraminifer faunas indicate more vigorous sea surface circulation and sea surface temperatures some degrees higher than known from the holocene during this warm period ice sheet growth began in northwest greenland the ice sheet reached its maximum for the last ice age during the succeeding phase provisionally correlated with isotope substage 5d this was followed by a new warm period with increased influx of warm subarctic water and high summer temperatures on land provisionally correlated with isotope substage 5a in east greenland the observations indicate a more complex ice sheet history the record from greenland is very similar to that obtained in adjacent coastal areas of the high arctic implying that the rapid shifts from warm to cold during isotope stage 5 were especially conducive to the formation of the embryonic north american and scandinavian ice sheets at high northern latitudes probably because the pulses of warm water were required to advect sufficient moisture into these areas to allow the growth of continental ice sheets

amino acid geochronology resolution and precision in carbonate fossils changes in indigenous proteins preserved in carbonate skeletons can be used to estimate the time elapsed since death of the organism racemization the most widely used reaction in amino acid geochronology refers to the inversion of l amino acids to their d configuration for the protein amino acid l isoleucine racemization occurs about only one of the two chiral carbon atoms this reaction epimerization proceeds from an initial dl ratio near zero to an equilibrium ratio of about 1 30 the reaction rate is controlled primarily by temperature and to a lesser degree by the nature of the proteins themselves a variable related to taxonomy and the extent of protein degradation analyzing monospecific samples minimizes the taxonomic variable the resolving power of dl ratios as relative age indices is a function of the reaction rate degree of natural variability and analytical uncertainty natural variability is defined as the spread in ratios in five well preserved shells of the same age from a single stratum and is primarily related to taxonomy it can range from 20 or more in taxa of low reliability to 1 in taxa of greatest integrity 5 to 10 is to be expected analytical uncertainty within a single laboratory is relatively insignificant amounting to no more than 2 but interlaboratory comparisons suggest caution in comparing ratios determined at different laboratories or by different techniques sampling appropriate portions of a shell is essential to minimize variability in dl ratios site temperature exerts the greatest control on reaction rate hence resolving power for tropical sites 25 c age differences 1 ka can be resolved within the holocene and ca 5 to 10 ka for older samples as the rate decreases equilibrium is attained after 150 to 300 ka the reaction rate is substantially lower at mid latitude sites ca 10 c where equilibrium requires about 2 ma and resolution within the last glacial cycle is no better than 10 to 20 ka arctic sites 10 c show almost no measurable racemization within the holocene and in extreme cases even within the last 100 ka equilibrium is not attained in 10 ma the extent of amino acid racemization epimerization in carbonate fossils provides chronological information for the critical time period beyond radiocarbon dating dl ratios can be used directly as relative age indices and with suitable calibration can provide reasonable estimates of absolute age and or effective diagenetic temperature improving the accuracy of racemization based age estimates requires a better understanding of racemization kinetics in carbonate systems

coastal aminostratigraphy of the last interglaciation in southern australia abstract amino acid racemization data for marine molluscs of the last interglaciation from southern australia provide the basis for a predictive model for relative dating of late quaternary sequences genera analyzed include anadara sp katelysia sp glycymeris sp and fulvia sp that exhibit moderate racemization rates a genus effect on racemization is not evident in these taxa coefficients of variation for intershell d l ratio variation for each deposit are generally less than 12 the extent of racemization in molluscan fossils of the last interglaciation from temperate coastal settings in southern australia represents an exponential function of temperature and is in general accord with data from northern hemisphere sites with similar contemporary mean annual temperature values these data highlight the potential of amino acid racemization for global correlation programs the amino acid data from southern australia suggest however that a larger margin of variation may have to be accounted for in stratigraphic correlation as indicated by the greater scatter of data around the oxygen isotope substage 5e isochron these data have implications regarding the age resolving power of amino acid racemization

mixing relationships in the martian regolith and the composition of globally homogeneous dust abstract comparison of the chemical compositions of martian soils reveals distinct mixing trends resulting from admixture of variable amounts of sulfate chloride cement at viking landing sites and of the local andesitic rock fragments at the mars pathfinder site these trends most easily visualized in plots of oxides versus so 3 intersect approximately at a common composition thought to represent a global dust that has been homogenized by pervasive aeolian activity the source rocks that were weathered to produce the global dust are inferred to have been basalts rather than felsic rocks based on the observation that the dust lies along well established chemical weathering trends for terrestrial basalts the basaltic protolith was chemically similar e g high fe mg low al 2 o 3 to basaltic shergottite meteorites chemical changes during the weathering of martian basaltic rocks are apparently not as drastic as in terrestrial weathering perhaps because of evaporation of hydrous fluids that leave soluble components behind in the residue comparison with chemical trends for previously proposed martian soil formation mechanisms suggests that palagonitization of basalts more readily explains the dust composition than do hydrothermal alteration at higher temperatures or reactions of rocks with an acid fog produced by volcanic exhalations local or temporal processing of dust into soil involves not only cementation by salts and mixing with rock fragments but also chemical fractionations of fe 2 o 3 tio 2 presumably resulting from aeolian sorting by grain size and density if the global dust represents a broad average of the martian surficial or upper crustal composition the planet s surface geology is dominated by basaltic volcanic rocks and evaporitic salts

the mars global digital dune database mgd3 global patterns of mineral composition and bedform stability abstract we present an expansion to the mars global digital dune database mgd3 describing 1 bulk dune field composition determined by fitting a mineral spectral library to thermal emission spectra tes data and 2 a morphologic stability index that measures the degree of non aeolian modification that has eroded and stabilized each dune field this paper describes results for these two components providing insight into global patterns of dune sand sources postdepositional alteration and mineral maturity consistent with the work of others the main mineral components of each analyzed dune field are feldspar pyroxene and high silica phases with minor amounts of olivine and possibly sulfate minerals subtle global scale spatial variations in olivine and feldspar abundances correspond with previously observed trends in surface mineralogy suggesting that dune sand is reflective of its regional setting and thus that aeolian sand has typically not traveled far

spatial grain size sorting in eolian ripples and estimation of wind conditions on planetary surfaces application to meridiani planum mars the landscape seen by the mars exploration rover mer opportunity at meridiani planum is dominated by eolian wind blown ripples with concentrated surface lags of hematitic spherules and fragments these ripples exhibit profound spatial grain size sorting with well sorted coarse grained crests and poorly sorted generally finer grained troughs these ripples were the most common bed form encountered by opportunity in its traverse from eagle crater to endurance crater field measurements from white sands national monument new mexico show that such coarse grained ripples form by the different transport modes of coarse and fine grain fractions on the basis of our field study and simple theoretical and experimental considerations we show how surface deposits of coarse grained ripples can be used to place tight constraints on formative wind conditions on planetary surfaces activation of meridiani planum coarse grained ripples requires a wind velocity of 70 m s at a reference elevation of 1 m above the bed from images by the mars orbiter camera moc of reversing dust streaks we estimate that modern surface winds reach a velocity of at least 40 m s and hence may occasionally activate these ripples the presence of hematite at meridiani planum is ultimately related to formation of concretions during aqueous diagenesis in groundwater environments however the eolian concentration of these durable particles may have led to the recognition from orbit of this environmentally significant landing site

global investigation of olivine on mars insights into crust and mantle compositions 1 we present the distribution of olivine on mars derived from spectral parameters based on the 1 m olivine absorption band the olivine can be defined with respect to two spectral end members type 1 corresponds to olivine with low iron content and or small grain size and or small abundance and type 2 which corresponds to olivine with higher iron content and or larger grain size and or larger abundance the spatial and statistical analysis of the global olivine distribution points out five major geological settings where olivine is detected 1 early hesperian olivine bearing smooth crater floors and flat intercrater plains throughout the southern highlands 2 olivine deposits around the three main basins argyre hellas and isidis 3 olivine in intercrater dunes crater ejecta or extended deposits in the northern plains 4 olivine associated with outcrops and sand in the floor of valles marineris and 5 olivine bearing butte outcrops in the vicinity of hellas the geological context the age and the composition of the olivine detections associated with these five major geological settings are detailed their origin and the implication of their occurrence on the composition of the martian mantle and crust as well as on the evolution of mars volcanism are discussed

physical abrasion of mafic minerals and basalt grains application to martian aeolian deposits abstract sediment maturity or the mineralogical and physical characterization of sedimentary deposits has been used to identify sediment sources transport medium and distance weathering processes and paleoenvironments on earth mature terrestrial sands are dominated by quartz which is abundant in source lithologies on earth and is physically and chemically stable under a wide range of conditions immature sands such as those rich in feldspars or mafic minerals are composed of grains that are easily physically weathered and highly susceptible to chemical weathering on mars which is predominately mafic in composition terrestrial standards of sediment maturity are not applicable in addition the martian climate today is cold and dry and sediments are likely to be heavily influenced by physical weathering rather than chemical weathering due to these large differences in weathering processes and composition martian sediments require an alternate maturity index this paper reports the results of abrasion tests conducted on a variety of mafic materials and results suggest that mature martian sediments may be composed of well sorted well rounded spherical polycrystalline materials such as basalt volcanic glass is also likely to persist in a mechanical weathering environment while more fragile and chemically altered products are likely to be winnowed away a modified sediment maturity index is proposed that can be used in future studies to constrain sediment source paleoclimate mechanisms for sediment production and surface evolution this maturity index may also provide insights into erosional and sediment transport systems and preservation processes of layered deposits

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

the anatomy and systematic position of the theropod dinosaur chilantaisaurus tashuikouensis hu 1964 from the early cretaceous of alanshan people s republic of china there is little consensus on the systematic position of the colossal theropod dinosaur chilantaisaurus tashuikouensis from the cretaceous aptian albian or upper cretaceous ulansuhai formation of inner mongolia which has been recovered as a derived member of both allosauroidea and spinosauroidea by numerical phylogenetic analyses redescription of the type material of c tashuikouensis reveals an unusual combination of morphological features that render determination of its systematic position problematic it possesses anatomical features that have been proposed as synapomorphies of neotetanurae a preacetabular fossa on the ilium and a wedge shaped cross section of the shaft of the third metatarsal it also shares some features with specific allosauroid taxa a pronounced ulnar epicondyle on the humerus and a prominent medial shelf bounding the preacetabular fossa on the ilium also present in tyrannosauroids however it lacks some features that are present in all other allosauroids a marked depression on the anterior surface of the distal humerus adjacent to the ulnar condyle and a humerus that is less than 0 4 times the length of the femur it furthermore possesses a tibial astragalar facet that is approximately 10 of the tibial length which suggests a more basal position within tetanurae chilantaisaurus shares certain features with some spinosauroids an enlarged and elongated first manual ungual and a suprastragalar buttress that has been modified to a vertical ridge but these characters are not unique to spinosauroids a highly reduced fourth trochanter may be an autapomorphy of chilantaisaurus as has previously been suggested or unite the taxon with coelurosauria in an entirely novel grouping on the basis of these observations it is likely that chilantaisaurus is a neotetanuran but unlikely that it is an allosauroid chilantaisaurus may belong to an alternative lineage of very large theropods that continued into the cretaceous from the diversification of basal neotetanurans during the middle jurassic

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

the particle size of martian aeolian dunes the effective particle size of unconsolidated materials on the martian surface can be determined from thermal inertia due to a pore size dependence of thermal conductivity at martian atmospheric pressures because dunes consist of a narrow range of well sorted unconsolidated particles they provide for a test of the relationship between particle size and thermal inertia calculated from midinfrared emission data for the martian surface we use two independent approaches first thermal inertia data indicate that martian dunes have an average particle size of about 500 100 m or medium to coarse sand second we determine expected dune particle sizes from grain trajectory calculations and the particle size transition from suspension to saltation on earth the transition occurs for a grain when the ratio of the terminal fall velocity to the wind friction speed u t is near unity for grains at u t this occurs at about 52 m terrestrial dune sands have a mean of 250 m and are composed entirely of grains 52 m the corresponding martian transition grain size is about 210 m suggesting that martian dunes should be significantly coarser than terrestrial dunes grain saltation path length as a function of particle size also shows that under martian conditions larger grains than on earth will become suspended both approaches indicate that martian dune sand should be coarser than terrestrial dune sand thus while terrestrial dune grains are in the fine to medium sand range the average martian dune sediments are probably medium to coarse sands these results closely match the grain sizes determined from thermal inertia models providing the first direct test of the validity of these models for actual martian surface materials

spectrophotometric properties of materials observed by pancam on the mars exploration rovers 2 opportunity 1 the panoramic camera pancam on the mars exploration rover opportunity acquired visible near infrared multispectral observations of soils and rocks under varying viewing and illumination geometries that were modeled using radiative transfer theory to improve interpretations of the microphysical and surface scattering nature of materials in meridiani planum nearly 25 000 individual measurements were collected of rock and soil units identified by their color and morphologic properties over a wide range of phase angles 0 150 at eagle crater in the surrounding plains in endurance crater and in the plains between endurance and erebus craters through sol 492 corrections for diffuse skylight incorporated sky models based on observations of atmospheric opacity throughout the mission disparity maps created from pancam stereo images allowed inclusion of local facet orientation estimates outcrop rocks overall exhibited the highest single scattering albedos 0 9 at 753 nm and most spherule rich soils exhibited the lowest 0 6 at 753 nm macroscopic roughness among outcrop rocks varied but was typically larger than spherule rich soils data sets with sufficient phase angle coverage resulting in well constrained hapke parameters suggested that models using single term and two term henyey greenstein phase functions exhibit a dominantly broad backscattering trend for most undisturbed spherule rich soils rover tracks and other compressed soils exhibited forward scattering while outcrop rocks were intermediate in their scattering behaviors some phase functions exhibited wavelength dependent trends that may result from variations in thin deposits of airfall dust that occurred during the mission

cosmogenic 3he production rates from holocene lava flows in iceland abstract we measured cosmogenic 3 he production rates in olivine phenocrysts from four radiocarbon dated postglacial basaltic lava flows in the western volcanic zone of iceland these measurements provide important new calibrations of cosmogenic nuclide production rates near sea level at high latitudes calibration sites from lambahraun 4040 250 cal yr bp n 4 leitahraun 5210 110 cal yr bp n 5 burfellshraun 8060 120 cal yr bp n 6 and ingvallahraun 10 330 80 cal yr bp n 4 yield a mean production rate of 132 5 atoms 3 he g 1 yr 1 1 normalized to sea level at high latitudes with the standard atmosphere mean production rates from the four flows agree within uncertainty indicating that these calibrations establish a reproducible local 3 he production rate that will significantly increase the accuracy of exposure dating in iceland the 3 he production rate in iceland is 17 higher than the mean of normalized holocene values previously determined in the western usa the high production rates in iceland are attributed to the influence of persistent low atmospheric pressure over iceland the icelandic low through the holocene which yielded higher cosmic ray fluxes the icelandic calibrations thus support previous suggestions that cosmogenic isotope production rates should be adjusted for regional variations in long term atmospheric pressure by extending the latitudinal extent of previous calibration studies these results are also useful for evaluating scaling models

determining olivine composition of basaltic dunes in gale crater mars from orbit awaiting ground truth from curiosity 1 the successful landing of the mars science laboratory curiosity rover in gale crater mars presents a rare opportunity for validation of a spectral index developed for determining olivine chemistry from orbital midinfrared remote sensing data here a spectral index is developed using laboratory emissivity data of 13 synthetic mg fe olivines utilizing this spectral index a prediction of olivine composition fo55 5 is made from orbital data for a ne sw trending dune field near the curiosity rover this dune field will be crossed during the mission as the rover travels toward a 5 km high sediment stack mount sharp that contains orbitally detected clays and sulfates curiosity can use its instrument suite chemmin alpha particle x ray spectrometer chemcam when it reaches the dunes to verify or refute the olivine chemistry prediction presented here the ability to validate the developed spectral index using the rover s ground truth instruments will strengthen olivine chemistry mapping across the martian surface using this spectral index

physical weathering and modification of a rhyolitic hyaloclastite in iceland fragmental volcanic glass or hyaloclastite is a common glaciovolcanic eruption product that is formed in large abundance during basaltic andesitic and rhyolitic subglacial eruptions the physical weathering of rhyolitic hyaloclastites differs notably from basaltic hyaloclastites due to differences in cementation and edifice consolidation as rhyolitic glasses are also much rarer comparatively little is known about their physical weathering and fracturing characteristics in the presented study we provide a process oriented analysis of the physical modification of subglacially erupted rhyolitic hyaloclastites from the blahnukur edifice in torfajokull iceland frost weathering experiments were performed to determine how vesicular glass particles fragment to finer particle sizes the surficial porosity of the glass drives such frost weathering through the process of pore pressurisation and was quantified using high pressure mercury intrusion uniaxial compression experiments were carried out to understand how the glass structure responds to the application of external stress the observed fracturing in both experimental treatments was found to adhere to fractal statistics which allowed the compression experiments to be used in conjunction with the frost weathering experiments for inferring the fracturing characteristics of rhyolitic volcanic glasses transport processes by wind and gravity were simulated by long duration abrasion experiments in rock tumblers through granular avalanching but these low energy particle interactions were not found to significantly abrade particles a notable result from our fragmentation experiments was the production of 10 m particles this size range is considered respirable and illustrates how physical weathering can continuously create potentially harmful ash textures a process which is often overlooked in health hazard assessments after volcanic eruptions fragmentation by post eruptive weathering can lead to overestimations of the fine ash fraction produced by syneruptive fragmentation and granulometric studies therefore need to be appreciative of the effects of such secondary fracturing processes

the last interglacial glacial cycle in the british isles abstract the amino acid geochronology of marine and non marine mollusca has enabled correlations to be made between the british isles europe and oxygen isotope stratigraphy the correlation between ipswichian and eemian is confirmed the chelford organic bed is correlated with the st germain i and amersfoort brorup events and the upton warren type site is correlated with the st germain ii and odderade events the implication of these correlations is that a considerable sedimentary record time equivalent to all of oxygen isotope stage 5 occurs in the fluvial systems of the southern british isles an early devensian glaciation is identified in north east scotland and north east ireland the asymmetrical development of this ice sheet when contrasted with the late devensian glaciation which extended farther south is attributed to differences in precipitation patterns during ice build up

climatic deterioration and the end of the gortian interglacial in sediments from derrynadivva and burren townland near castlebar county mayo ireland pollen and macrofossil analyses of two sequences of organic sediment in western ireland have allowed the recognition of the latter parts of the gortian interglacial a middle pleistocene temperate stage the palaeobotanical information from the two sites identifies the preservation of partial sequences from the gortian interglacial believed to be the equivalent of the hoxnian stage of britain and the holsteinian of europe the pollen and macrofossil data from one of the sites derrynadivva span the middle and latter parts of the temperate stage the results show that fire influenced the vegetation throughout the middle part of the temperate stage and the termination of the organic depositional sequence appears to have been due to environmental deterioration the former is identified through the abundant occurrence of charcoal in the sediments whereas the latter is apparent in the sediment sequence and in the reworking of thermophilous pollen types into the upper part of the deposit the second site burren townland records only part of the later zones of the interglacial but the ericaceous assemblages of the latter part of the gortian interglacial are well developed and well preserved macrofossil analyses and scanning electron microscopy work on the pollen at the latter site has allowed the recognition of rhododendron ponticum adding to previous records of this species which now has a very disjunct european distribution

the chronology palaeogeography and archaeological significance of the marine quaternary record of the west sussex coastal plain southern england u k abstract the quaternary sediments of the west sussex coastal plain have produced a wide range of floral faunal and archaeological remains these sediments consist of marine sands and gravels exhibiting transgressive and regressive trends which occur from present day sea level to c 43 0 m o d and are overlain by terrestrial silts and cold climate periglacial sediments at the present day coastline channel fill deposits occur below modern beach levels new field observations coupled with a re investigation of old sites and literature suggest that five discrete high stands of sea level may be preserved in the area of the west sussex coastal plain age estimates for these deposits suggest that they span large parts of the middle and upper pleistocene oxygen isotope stages 13 to 5 conformable relationships between many of the marine and terrestrial sediments suggest that the potential exists within the area to correlate the marine and terrestrial quaternary stratigraphic records in addition sediments associated with two of these high sea level stands are associated with extensive buried landsurfaces covering large areas of the coastal plain at some locations these intact landsurfaces are associated with evidence for human activity and represent stratigraphic and cultural resources of international importance

composition of conglomerates analyzed by the curiosity rover implications for gale crater crust and sediment sources the curiosity rover has analyzed various detrital sedimentary rocks at gale crater among which fluvial and lacustrine rocks are predominant conglomerates correspond both to the coarsest sediments analyzed and the least modified by chemical alteration enabling us to link their chemistry to that of source rocks on the gale crater rims in this study we report the results of six conglomerate targets analyzed by alpha particle x ray spectrometer and 40 analyzed by chemcam the bulk chemistry derived by both instruments suggests two distinct end members for the conglomerate compositions the first group darwin type is typical of conglomerates analyzed before sol 540 it has a felsic alkali rich composition with a na2o k2o 5 the second group kimberley type is typical of conglomerates analyzed between sols 540 and 670 in the vicinity of the kimberley waypoint it has an alkali rich potassic composition with na2o k2o 2 the variety of chemistry and igneous textures when identifiable of individual clasts suggest that each conglomerate type is a mixture of multiple source rocks conglomerate compositions are in agreement with most of the felsic alkali rich float rock compositions analyzed in the hummocky plains the average composition of conglomerates can be taken as a proxy of the average igneous crust composition at gale crater differences between the composition of conglomerates and that of finer grained detrital sediments analyzed by the rover suggest modifications by diagenetic processes especially for mg enrichments in fine grained rocks physical sorting and mixing with finer grained material of different composition