global scale near infrared variability on mars analysis of 2003 mars opposition observations from hst nicmos abstract we have used hst nicmos to observe approximately 57 of the martian surface in 7 narrow band filters 0 97 1 08 1 13 1 66 1 90 2 12 and 2 15 m during the 2003 opposition l s 250 and at a resolution of 12 km pixel principal components analysis pca of the dataset has identified regional variability on scales of hundreds of kilometers associated with differences in the near infrared spectrum of mars visualization of the data in principal component space has allowed us to identify spectral endmembers associated with the south polar cap the classic bright terrains northern syrtis major southern syrtis major tyrrhena terra and acidalia planitia the two syrtis major endmembers and the tyrrhena terra endmember differ in their absolute reflectivities but have the same spectral shape at wavelengths longer than 1 6 m the acidalia endmember is distinct from the other dark terrain endmembers because it exhibits a strong negative near ir spectral slope comparisons with spectral library measurements cannot provide unique constraints on the surface mineralogy for these sparsely sampled spectral data however the observed spectral variations between tyrrhena terra and syrtis major are consistent with variations in iron and sulfur bearing minerals and the relatively strong negative spectral slope in the spectrum of acidalia is consistent with the presence of hydrated alteration products additional comparison with previous nicmos observations taken in 1997 at l s 150 indicate that the average near ir spectral slope of the acidalia region is more negative during the late northern fall than during the mid northern summer this may indicate seasonal variations in the presence of either adsorbed water or re hydrated minerals in the regolith of acidalia

paleolakes paleofloods and depressions in aurorae and ophir plana mars connectivity of surface and subsurface hydrological systems abstract the plains of aurorae and ophir in the equatorial region of mars display geomorphic evidence indicative of extensive but generally short lived paleohydrological processes elaver vallis in aurorae planum south of ganges chasma is an outflow channel system 180 km long and here inferred to have formed by cataclysmic spillover flooding from a paleolake s contained in the morella crater basin ganges cavus is an enormous 5 km deep depression of probable collapse origin located in the morella basin the fluid responsible for the infilling of the morella basin likely emerged at least partially through ganges cavus or its incipient depression and it may have been supplied also from small scale springs in the basin similar paleohydrological processes are inferred also in ophir planum it is reasonable to assume that water sometimes sediment laden and or mixed with gases was the responsible fluid for these phenomena although some of the observed features could be explained by non aqueous processes such as volcanism water emergence may have occurred as consequences of ground ice melting or breaching of cryosphere to release water from the underlying hydrosphere dike intrusion is considered to be an important cause of formation for the cavi and smaller depressions in aurorae and ophir plana explaining also melting of ground ice or breaching of cryosphere alternatively the depressions and crater basins may have been filled by regional groundwater table rising during the period s when cryosphere was absent or considerably thin the large quantities of water necessary for explaining the paleohydrological processes in aurorae and ophir plana could have been derived through crustal migration from the crust of higher plains in western ophir planum where water existed in confined aquifers or was produced by melting of ground ice due to magmatic heating or climatic shift or from a paleolake in candor chasma further west

phyllosilicate poor palagonitic dust from mauna kea volcano hawaii a mineralogical analogue for magnetic martian dust the mineralogical and elemental composition of dust size fractions 2 and 5 m of eight samples of phyllosilicate poor palagonitic tephra from the upper slopes of mauna kea volcano hawaii were studied by x ray diffraction xrd x ray fluorescence xrf visible and near ir reflectance spectroscopy mossbauer spectroscopy magnetic properties methods and transmission electron microscopy tem the palagonitic dust samples are spectral analogues of martian bright regions at visible and near ir wavelengths the crystalline phases in the palagonitic dust are in variable proportions plagioclase feldspar ti containing magnetite minor pyroxene and trace hematite no basal reflections resulting from crystalline phyllosilicates were detected in xrd data weak broad xrd peaks corresponding to x ray amorphous phases allophane nanophase ferric oxide possibly ferrihydrite and for two samples hisingerite were detected as oxidative alteration products of the glass residual unaltered glass was also present mossbauer spectroscopy showed that the iron bearing phases are nanophase ferric oxide magnetite titanomagnetite hematite and minor glass and ferrous silicates direct observation by tem showed that the crystalline and x ray amorphous phases observed by xrd and mossbauer are normally present together in composite particles and not normally present as discrete single phase particles ti bearing magnetite occurs predominantly as 5 150 nm particles embedded in noncrystalline matrix material and most likely formed by crystallization from silicate liquids under conditions of rapid cooling during eruption and deposition of glassy tephra and prior to palagonitization of glass rare spheroidal halloysite was observed in the two samples that also had xrd evidence for hisingerite the saturation magnetization js and low field magnetic susceptibility for bulk dust range from 0 19 to 0 68 am2 kg and 3 4 10 6 to 15 5 10 6 m3 kg at 293 k respectively simulation of the mars pathfinder magnet array ma experiment was performed on mauna kea volcano in areas with phyllosilicate poor palagonitic dust and with copies of the pathfinder ma on the basis of the magnetic properties of dust collected by all five ma magnets and the observation that the pathfinder mas collected dust on the four strongest magnets the value for the saturation magnetization of martian dust collected in the ma experiments is revised downward from 4 2 am2 kg to 2 5 1 5 am2 kg the revised value corresponds to 2 7 1 6 wt magnetite if the magnetic mineral is magnetite using js 92 am2 kg for pure magnetite fe3o4 or to 5 0 3 0 to 3 4 2 0 wt maghemite if the magnetic mineral is pure maghemite using js 50 to 74 am2 kg for pure maghemite fe2o3 comparison of the magnetic properties of bulk mauna kea palagonitic dust to those for dust collected by ma magnets shows that the ma magnets extracted culled a subset 25 34 wt of composite magnetic particles from bulk dust the extent of culling of martian dust is not well constrained because the mauna kea palagonitic dust satisfies the essential constraints of the pathfinder magnetic properties experiment composite and magnetic particles capable of being collected by five ma magnets a working hypothesis for the strongly magnetic mineral present in martian dust and soil is magnetite possibly ti bearing formed by rapid crystallization from silicate liquids having volcanic and or impact origins subsequent palagonitization of the glass produces the nanophase ferric oxide phases that dominate the spectral properties of martian bright regions at visible and near ir wavelengths magnetic and phyllosilicate poor palagonitic dust from mauna kea volcano is thus a spectral and magnetic analogue for magnetic martian dust

evidence of 550 year and 1000 year cyclicities in north atlantic circulation patterns during the holocene sedimentological colour data obtained from north atlantic deep sea sediment core neap15k pro vide a continuous climate record for the last 11500 yr with a mean sampling interval of 15 yr variations in sediment lightness a proxy for changes in north atlantic deep water nadw circulation are characterized by high frequency fluctuations with periodicities equivalent to 550 and 1000 yr as well as a 1600 yr cyclicity comparable to that reported in other studies of holocene climate cross spectral analysis suggests that the 550 yr and 1000 yr cyclical variations in nadw circulation were coherent with fluctuations in atmospheric con ditions over greenland where both these periodicities have been identified previously in the holocene gisp2 d18o record stuiver et al 1995 a similar statistical comparison provides evidence that high frequency 550 yr variability in nadw circulation patterns may have been linked to short term variations in atmospheric 14c values during the holocene in general nadw pro

enhancement of coccolithophorid blooms in the bering sea by recent environmental changes 1 since 1997 ocean color satellite images have revealed large scale blooms of the coccolithophorid emiliania huxleyi in the eastern bering sea the blooms are often sustained over several months and have caused ecosystem changes in the arctic ocean as well as in the bering sea we examined continental shelf sediment profiles of alkenone a biomarker for e huxleyi covering the past 70 years the alkenone records suggest that large e huxleyi blooms are a novel feature in the bering sea as they have occurred only since the late 1970s recent changes in alkenone content were closely related to the 1976 77 climatic regime shift in the north pacific implying that warming and freshening of bering sea waters promoted e huxleyi blooms the production rate of diatoms total valves in sediment samples the dominant primary producers in the bering sea also increased during the past several decades however the ratio of alkenone content to total diatom valves in the sediments increased as e huxleyi production increased suggesting that the increase in the e huxleyi production rate frequently exceeded the increase in the diatom production rate overall our results indicate a possible subarctic region ecosystem shift driven by climate change

a structural study of an interior layered deposit in southwestern candor chasma valles marineris mars using high resolution stereo camera data from mars express 1 an interior layered deposit ild within western candor chasma of valles marineris mars is examined using data from the high resolution stereo camera of the mars express mission most ild layers dip in the same direction as the topographic slope exposed rotated fault blocks of basement lithology appear to penetrate the cover of this ild deposit in at least two locations these features suggest a simple drape morphology over basement topography consisting of rotated fault blocks this interpretation constrains possible hypotheses of ild formation and suggests a limit on total volume of ild material draping implies low energy deposition either subaerially or in deep water and that the total volume of ild is considerably less than indicated by the size of the mound a dark competent unit unconformably caps part of the ild indicating a multistage depositional history

spectral and geological study of the sulfate rich region of west candor chasma mars sulfates have been discovered by the omega spectrometer in different locations of the planet mars they are strongly correlated to light toned layered deposits in the equatorial regions west candor chasma is the canyon with the thickest stack of layers and one with the largest area covered by sulfates a detailed study coupling mineralogy derived from omega spectral data and geology derived from hrsc imager and other datasets leads to some straightforward issues the monohydrated sulfate kieserite is found mainly over heavily eroded scarps of light toned material it likely corresponds to a mineral present in the initial rock formed either during formation and diagenesis of sediments or during hydrothermal alteration at depth because it is typically found on outcrops that are eroded and steep polyhydrated sulfates that match any ca na fe or mg sulfates with more than one water molecule are preferentially present on less eroded and darker outcrops than outcrops of kieserite these variations can be the result of a diversity in the composition and or of the rehydration of kieserite on surfaces with longer exposure the latter possibility of rehydration in the current or recent atmosphere suggests the low surface temperatures preserve sulfates from desiccation and also can rehydrate part of them strong signatures of iron oxides are present on sulfate rich scarps and at the base of layered deposits scarps they are correlated with tes gray hematite signature and might correspond to iron oxides present in the rock as sand size grains or possibly larger concretions that are eroded and transported down by gravity at the base of the scarp pyroxenes are present mainly on sand dunes in the low lying terrains pyroxene is strongly depleted or absent in the layered deposits when mixed with kieserite local observations favor a spatial mixing with dunes over layered deposits sulfates such as those detected in the studied area require the presence of liquid water to form by precipitation either in an intermittent lacustrine environment or by hydrothermal fluid circulation both possibilities require the presence of sulfur rich groundwater to explain fluid circulation the elevation of the uppermost sulfate signatures suggests the presence of aquifers up to 2 5 km above datum only 1 km below the plateau surface

correlation of climate cycles in middle mississippi valley loess and greenland ice two complete late wisconsin loess successions in the middle mississippi river valley reveal 39 and 41 alternating paleosol a and c horizons striking changes in soil color iron content and carbonate content define four major and two minor paleosol a horizon complexes which were interpreted to represent wisconsin interstadials 1 2 3 4 and semiinterstadials 1 5 and 2 5 respectively the timing of wisconsin interstadials matches that of corresponding greenland interstadials midcontinent loess and greenland ice records as well as rates of atmospheric 14c production have periodicities in common suggesting a solar influence only a persistent heat and moisture supply could produce prominent paleosol complexes near the continental ice margin this record suggests that el nino southern oscillation variability has amplified solar forcing and resultant tropical heat and moisture transport played a significant role in millennial and centennial scale climate cycles during the late wisconsin glaciation over the northern hemisphere

extracting science from mossbauer spectroscopy on mars 1 deployment by the mars exploration rovers of backscatter mossbauer spectrometers offers an incredible opportunity to 1 elucidate the iron mineralogies of rocks soils and atmospheric dust and 2 gain insight into the physical event by which the mineralogy came into existence and consequently acquire information having potential for yielding ancient planetary history relevant to broad issues including the question of life determining the mineralogy is done by subjecting raw data to reduction algorithms and generating products known as mossbauer parameters which are highly characteristic mixed mineralogies are treated through deconvolution through being able to exploit mossbauer measurements made at different temperatures during the martian diurnal variation and utilizing spectra obtained of the same sample with both the 6 4 and 14 4 kev energy channels characteristics beyond oxidation state and stoichiometry are accessible these include temperature sensitive magnetic transitions that can be either abrupt or gradual variation of mossbauer parameters with temperature and variation of composition with depth all of which can be dependent upon past processing affecting initial crystallization or subsequent alteration weathering the goal is to arrive at an understanding of environments including the very ancient

geochemical evidence for abrupt changes in relative strength of the arabian monsoons during a stadial interstadial climate transition the occurrence and propagation of abrupt climate change between the high and low latitudes has become an important focus of paleoclimatic and paleoceanographic research the causes of abrupt change have significant implications for understanding future manifestations of similar forcings under late holocene anthropocene boundary conditions of particular interest are signals indicative of sub millennial scale climate change in the sub tropics of similar magnitude and frequency to those recorded in greenland ice cores earlier research in the arabian sea has highlighted the sensitivity of sedimentary organic carbon and nitrogen isotope measurements for recording the state of the sw monsoon and associated arabian sea oxygen minimum zone in this study we exploit the unprecedented fidelity of the sedimentary 15n record to identify a 20 cm interval at odp site 723 containing a stadial inter stadial interval between 43 42 kyr bp we employ sedimentary nitrogen isotopes chlorin pigment and alkenone abundances major and minor element analyses of highly resolved 2 mm 10 yr samples across this interval to compare a comprehensive multi proxy data set to understand a the processes contributing to the 15n signal in the longer records of denitrification and b the associated climatic events especially the relative intensity of summer and winter monsoons at these times a lack of evidence for bioturbation in excess of our 2 mm sampling resolution facilitates decadal scale oceanographic and climatic reconstructions using a four component flux dilution model we show that the deposition of carbonate decreased in parallel with an increase in total organic matter flux from stadial to inter stadial time this interval is also marked by a significant drop in lithogenic dust accumulation analogous to a similar decrease noted during deglaciation in the western arabian sea combined with alkenone u37k derived estimates for sea surface temperature sst we conclude that the climatological shift from stadial to inter stadial conditions at low latitudes was characterized by repeated switches in mean monsoon state approximately every 200 yr the winter monsoon was the dominant mode during maximum stadial conditions conversely the summer monsoon was dominant during maximum interstadial like conditions however each interval was separated by a distinct inter monsoon mode indicated by a higher continental dust flux but warmer sst proxy records for changing bottom water oxygenation show near identical results down to the mm scale but hint at increased export production leading the onset of anoxia during the stadial inter stadial transition the coherence of all sedimentary signals depicts a wholesale reorganization of the arabian sea climate and marine ecosystem over approximately 200 years a period that may be associated with monsoon modulation by small oscillations in solar irradiance

ash layers from iceland in the greenland grip ice core correlated with oceanic and land sediments four previously known ash layers ash zones i and ii saksunarvatn and the settlement layer all originating in iceland have been identified in the central greenland ice core grip this correlation of the ash between the different environments is achieved by comparison of the chemical composition of glass shards from the ash this establishes and confirms detailed correlations between the different types of depositional records and the absolute dating of the younger part of the ice core by counting annual layers dates the eruptions accurately a precise connection with dates obtained by14c beyond the range of dendrochronology is established which provides an excellent confirmation of230th 234u dates from corals four additional icelandic ash layers have also been identified in the core but not yet correlated with known ash deposits

multi proxy records showing significant holocene environmental variability the inner n iceland shelf hunafloi abstract over the last 50 yr the n iceland margin has seen dramatic changes in temperature and salinity associated with the relative dominance of warm atlantic water versus cold arctic or polar waters we report a study of holocene environmental changes to assess the sensitivity of this area on a longer timescale we present sedimentologic isotopic and biotic coccolith proxies from a 5 5 m piston core b997 330pc that was retrieved from a small basin on the inner n iceland shelf seven ams dates indicate a relatively constant rate of sediment accumulation which averaged 55 cm kyr sampling resolution of our proxies varied between 16 and 90 yr sample our data indicate substantial variability in environmental conditions over the last 10 000 cal yr total carbonate content and coccolith concentrations track each other and indicate that the early holocene was a time of low net carbonate accumulation net accumulation of carbonate reached maximum values in the mid to late holocene 4 2 cal ka but there has since been a substantial decrease with a minima during the little ice age north atlantic drift coccolith species show peaks in accumulation rates at 2 and 8 cal ka and low influx between 3 5 and 6 cal ka reworked neogene coccoliths occur also 8 ka and coincide with light 18 o values in the epifaunal foraminifera cibicides lobatulus principal component analysis indicates considerable covariance between biotic isotopic and sedimentological parameters three axes explain 84 of the variance in the data set and define three groups of interrelated variables a major change occurs ca 5 cal ka after which conditions become more variable with a 1 5 kyr cyclicity

intra arc deformations with vertical rotation axes the case of the pre middle miocene terranes of southwest japan abstract various folds bends with vertical or subvertical rotation axes occur in the pre middle miocene terranes of southwest japan they are variable in shape conical folds accordion folds megakink bands and so on and some are accompanied with strike slip faults they range from several kilometers to more than 100 km in width and some of their hinge surfaces are traceable more than a few tens of kilometers their shapes which resemble megakink band or buckle folds indicate that they were produced by horizontal compression with vertical or subvertical 2 axes in a shallow level of the crust they were superimposed on the pre middle miocene fold and thrust structures or nappe melange complexes and are regarded to have been formed mostly during the middle miocene contemporaneous with the clockwise rotation of southwest japan related to the fan shaped opening of the sea of japan geometrical analysis clearly suggests that the drifting southwest japan behaved as a non rigid body and the formation of these structures resulted from the differential rotation of the terranes and the collision of the izu bonin arc with eastern southwest japan

an unusual spectral unit in west candor chasma evidence for aqueous or hydrothermal alteration in the martian canyons abstract high spatial resolution observations made by orbiting spacecraft from the viking and phobos missions suggest the local development of crystalline ferric oxides in a small area in mars valles marineris canyon system quantitative color analysis of viking orbiter multispectral images identifies two spatially coherent regions of unique hue among the interior layered deposits in western candor chasma the anomalous color indicates a local compositional difference between these regions and the surrounding high albedo materials the unusual appearance of the unit in the viking color observations could be explained by a small increase in the degree of crystallinity or abundance of hematite near infrared spectra obtained by the ism imaging spectrometer aboard phobos 2 confirm a local enrichment in ferric oxides or oxyhydroxides in the region and suggest the presence of another phase in addition to hematite in high resolution the spectral unit can be seen to occur within two 20 km long depressions on the margins of an hesperian aged layered deposit which forms a plateau on the chasma floor water is implicated in the formation of the iron oxides since the same sedimentary layers seen in the depressions are exposed on steep surfaces elsewhere on the plateau but show no evidence of unusual coloration this suggests that the mineralization occurred through secondary alteration of preexisting rocks and developed locally in association with the depressions which could have ponded surface runoff or groundwater seepage

identification of quartzofeldspathic materials on mars 1 a unique spectral component has been identified near and on the central peaks of two 30 km diameter craters in northern syrtis major these exposures are clearly visible in thermal emission imaging system themis color radiance images as well as themis and thermal emission spectrometer tes surface emissivity data both tes and themis data indicate the presence of increased 1050 1250 cm 1 8 9 5 m absorption compared to the surrounding basaltic plains and tes data also display other absorptions at 400 470 and 800 cm 1 25 20 and 12 m consistent with the presence of quartz ratio and isolated central peak spectral unit spectra match laboratory emissivity spectra of granitoid rocks composed primarily of quartz and plagioclase feldspar deconvolution results also indicate that the surface contains quartz and feldspar in addition to a high si glass and or sheet silicate component because central peak materials are brought up from depth during the cratering event the association of the quartzofeldspathic mineralogy with the central peaks of the craters indicates that the quartz bearing material was excavated from depth the occurrence in the two adjacent craters may imply a granitoid pluton of considerable extent a plausible formation mechanism for this relatively silicic material may be similar to that of terrestrial trondhjemites which do not require plate tectonics the rarity of the exposures implies that the process that formed the granitoid composition was probably not widespread the presence of quartz bearing material on mars indicates that mechanisms that produce highly differentiated magmas have been present and extends the diversity of surface compositions identified

a mid late quaternary loess paleosol record in simmons farm in southern illinois usa abstract in unglaciated areas of the mississippi valley region the typical full loess paleosol succession contains the modern soil developed in peoria silt weakly developed farmdale geosol developed in roxana silt sangamon geosol developed in loveland silt and yarmouth geosol developed in crowley s ridge silt although a fifth loess called the marianna silt is reported at one area the paleosol that separates the crowley ridge and marianna silts is not well defined previous thermoluminescence tl and optical stimulated luminescence osl age chronology has suggested multiple phases of sangamon geosol developed in loveland silt but clear morphological evidence of polygenetic sangamon geosol profiles have not been found recently a thick loess paleosol sequence has been studied in the middle mississippi valley in unglaciated southern illinois usa soil morphology and analytical results revealed five loesses and associated paleosol units two sangamon bt horizons were found separated by a thick actk horizon interpreted to indicate two phases of sangamon geosol development this well preserved loess paleosol succession provides one of the most complete mid late quaternary loess records in the middle mississippi valley to date and is important for studying the stratigraphic framework and paleoclimate and environment changes

new evidence for a magmatic influence on the origin of valles marineris mars in this paper we show that the complex geological evolution of valles marineris mars has been highly influenced by the manifestation of magmatism e g possible plume activity this is based on a diversity of evidence reported here for the central part melas chasma and nearby regions including uplift loss of huge volumes of material flexure volcanism and possible hydrothermal and endogenic induced outflow channel activity observations include 1 the identification of a new 50 km diameter caldera vent like feature on the southwest flank of melas which is spatially associated with a previously identified center of tectonic activity using viking data 2 a prominent topographic rise at the central part of valles marineris which includes melas chasma interpreted to mark an uplift consistent with faults that are radial and concentric about it 3 hirise identified landforms along the floor of the southeast part of melas chasma that are interpreted to reveal a volcanic field 4 crism identification of sulfate rich outcrops which could be indicative of hydrothermal deposits 5 grs k th signature interpreted as water magma interactions and or variations in rock composition and 6 geophysical evidence that may indicate partial compensation of the canyon and or higher density intrusives beneath it long term magma tectonic and water interactions late noachian into the amazonian albeit intermittent point to an elevated life potential and thus valles marineris is considered a prime target for future life detection missions

spectrocolorimetric interpretation of sedimentary dynamics the new q7 4 diagram colour is a fundamental property of sediment and is often used for lithographic description to determine sedimentological structures facies etc however the sedimentary information contained in this parameter is difficult to extract because it is difficult to quantify colour can be quantified by spectrocolorimetry which provides very high resolution data quickly and non destructively when adapted to sedimentology spectrocolorimeters prove to be powerful tools due to their low purchase and maintenance costs and some are portable and easily used in the field several methods have been used to extract sedimentological data from colorimetric spectra first derivatives factorial analysis etc in the present study we first provide a review of the sedimentological application of spectrophotometers and after having described these methods their advantages and disadvantages we then describe a new tool called the q7 4 diagram abscissa l ordinates 700 400 ratio this new technique permits sedimentological units to be defined allows the identification of different sediment components and provides 5 distinct poles clayey deposits organic rich deposits chlorophyll a and by products altered organic matter deposits iron rich deposits carbonated deposits coupled with the analysis of first derivative spectra it is possible to distinguish different pigments linked to the degradation and or nature of the organic material chlorophyll a melanoidin etc the state of iron oxidation for example hematite and goethite like signatures and the nature of clays the q7 4 diagram permits rapid acquisition of high resolution data on changes of sediment dynamics in geosystems that have been subjected to highly varied climatic environmental conditions the instrument is non destructive easy to use and maintain portable for use in the field fast to implement is capable of high resolution and has a vast range of possible applications spectrocolorimetry appears to provide many advantages and could become an essential and robust tool for preliminary sedimentological studies

reconstruction of the last deglaciation deconvolved records of δ18o profiles micropaleontological variations and accelerator mass spectrometric14c dating bioturbation acts as a low pass filter in displacing and reducing the amplitudes of stratigraphic signals this often leads to a loss of high frequency events in the stratigraphic record in addition when considering an isotopic signal 18o 14c measured in stratigraphic carriers such as foraminifera bioturbation and carrier abundance changes can create artifacts which may be falsely interpreted as leads or lags in the paleoclimatic record

coherent tilt signals observed in the shumagin seismic gap detection of time dependent subduction at depth repeated surveys of short level lines in the shumagin islands alaska reveal coherent tilt signals associated with subduction of the pacific plate beneath the north american plate in the shumagin seismic gap ten years of steady tilt down toward the trench is interrupted during 1978 1980 by a rapid episode of reverse tilt the normal tilt represents surface deformation as subduction occurs with the plate boundary locked to at least 60 km depth using all available tilt sea level and seismic data the authors interpret the tilt reversal as due to an episodic reverse slip of ca 80 cm magnitude on the plate boundary between ca 70 km and ca 20 km depth downdip from the main seismogenic zone which remains locked this event causes an increase of stress on the locked main thrust zone the authors speculate that such events may be a regular process at subduction zones that great plate boundary earthquakes may be more common during their occurrence and that their onset may be detectable early enough to give warning of an increase in probability for the occurrence of a great earthquake 51 references 10 figures 1 table

the flickering switch of late pleistocene climate change polar ice contains a unique record of past climate variations previous greenland ice cores have documented relatively warm interstadial periods during the last glaciation and short centuryscale returns to colder conditions during the glacial to interglacial warming see for example ref 1 these climate features have also been observed to varying degrees in ocean sediment cores2 4 and terrestrial pollen and insect records5 7 here we report electrical conductivity measurements from a new greenland ice core which confirm these previous observations and also reveal a hitherto unrecognized mode of rapid climate variation fluctuations in ice conductivity on the scales of 5 20 years reflect rapid oscillations in the dust content of the atmosphere this flickering between two preferred states would seem to require extremely rapid reorganizations in atmospheric circulation

alkenones and multiproxy strategies in paleoceanographic studies 1 we assess multiproxy strategies involving alkenone based and other paleoceanographic indicators in an effort to define uncertainties and to advance understanding of past oceanic and climatic changes looking to the future we recommend a parallel strategy of applying proxies to the geologic record while continuously seeking refinements in methods and understanding of mechanisms that control each proxy a multiproxy strategy increases confidence in results and provides oceanographic context for more effective interpretation of processes a combination of proxies allows derivation of additional properties such as upper ocean paleosalinity or paleo pco2 for a more complete view of the oceanographic and climate mechanisms involved in changing earth s environment

mixed hydrothermal fluids and the origin of the martian soil the martian soil consists mainly of weathered basaltic rock and a salt component enriched in volatile and mobile elements primarily sulfur chlorine sodium and potassium since the discovery of this mobile element component by the viking x ray fluorescence spectrometer volcanic aerosols have been considered a likely source for these enrichments alternative sources of the mobile element component are fluids supplied to the surface by hydrothermal processes related to impact craters and volcanism we show that a mixed hydrothermal fluid model can successfully explain the composition of the mobile element component of the soil this model is constructed using terrestrial analogs constrained by the viking and pathfinder measurements of the martian soil chemistry the potential hydrothermal fluid contributions to the soil are tightly constrained because the relative abundances of the mobile elements in hydrothermal fluids are nearly constant the two end member types of hydrothermal fluids considered in the model are the neutral chloride and the acid sulfate type the neutral chloride fluids have high cl and na contents and a significant amount of k but their s abundance relative to cl s cl ratio is too low to match the martian soil however acid sulfate hydrothermal systems characterized by substantial vapor transport and high s cl ratios are likely on mars due to the low abundance of water indeed as the availability of water declines in a hydrothermal system the neutral chloride system can evolve to a vapor dominated acid sulfate system a combination of the two types of fluids can quantitatively explain the s and cl abundance in the soil and provide reasonable abundances of other mobile elements including na k and br without predicting an excess of any element measured in the soil however the hydrothermal fluids are unlikely to be involved in the formation of the magnetic minerals in the soil because the fe contents of the fluids are too low although the acid sulfate fluids have fe concentrations a factor of 100 larger than the neutral chloride fluids the acid sulfate fluids would contribute less than 1 of the total fe in the soil the volcanic aerosol models are poorly constrained in contrast to the hydrothermal fluid models because in volcanic aerosols the relative abundances of the mobile elements are highly variable therefore while volcanic aerosols can explain the mobile element component of the soil significant contributions from other sources cannot be excluded determining the relative contributions of hydrothermal components compared to volcanic aerosols will require measurements in the martian soil of trace elements that provide signatures of the hydrothermal fluids such as high lithium contents that are associated with neutral chloride fluids

discrimination of poorly exposed lithologies in imaging spectrometer data high spectral resolution imagery produced by imaging spectrometers enables the discrimination of geologic materials whose surface expression is subpixel in scale moreover the use of such data makes it possible to distinguish materials which are characterized only by subtle differences in the spectral continuum we define the continuum as the reflectance or radiance spanning the space between spectral features the capability to distinguish subpixel targets will prove invaluable in studies of the geology of the earth and planets from airborne and spaceborne imaging spectrometers however subpixel targets can only be uniquely identified in a truly optimal sense through the application of data reduction techniques that model the spectral contribution of both target and background materials two such techniques are utilized herein they are a spectral mixture analysis approach and a low probability detection routine based on orthogonal subspace projection these techniques were applied to the problem of detecting two different volcanic tuff units one basaltic and one rhyolitic in two different scenes of data measured by the airborne visible infrared imaging spectrometer aviris these tuff units have limited exposures from an overhead perspective and have spectral signatures which differ from those of background materials only in terms of subtle slope changes in the reflectance continuum of the two approaches it was found that the low probability detection algorithm was more effective in highlighting those pixels that contained the target tuff units while suppressing the response of undesired background materials

low temperature reflectivity spectra of red hematite and the color of mars reflectivity spectra visible and near ir were measured near 141 210 and 300 k for four red and well crystalline powders of hematite red hematite used as commercial pigments two samples of volcanic tephra from mauna kea volcano that contain red hematite as their dominant pigment three samples of palagonitic tephra from the same location that contain nanophase ferric oxide as their dominant pigment and two mixtures of the two types of pigmenting phases relative proportions of red hematite and nanophase ferric oxide were determined by mossbauer spectroscopy for samples containing red hematite as the dominant pigment the positions of the ferric electronic transitions near 430 500 630 and 860 nm are essentially independent of temperature but their widths decrease with decreasing temperature this decrease results in a well defined minimum for the band at 630 nm at low temperatures and in significant increases in reflectivity in spectral regions near 1050 and 600 nm for example the reflectivity ratios r 600 r 530 and r 600 r 860 both increase by a factor as large as l 4 between 300 and 140 k the spectral features from nanophase ferric oxide in samples of palagonitic tephra are nearly independent of temperature spectral data of martian bright regions that are characterized by a shallow band minimum near 860 nm a reflectivity maximum near 740 nm a distinct bend near 600 nm and a shallow absorption edge from 400 to 740 nm are attributed to the presence of nanophase ferric oxide plus subordinate amounts of red hematite the 600 740 and 860 nm features are associated with red hematite because the reflectivity of red hematite at 600 nm is strongly dependent on temperature and because this wavelength is in the red part of the visible spectrum the color of the martian surface may vary as a function of its temperature a conservative upper limit for the red hematite content of the optical surface of mars is 5

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

dansgaard oeschger events is there a signal off the hudson strait ice stream abstract it is generally accepted that the dramatic heinrich h events were principally sourced from the major hudson strait drainage basin of the laurentide ice sheet but it is not known whether the higher frequency dansgaard oeschger d o events have an imprint on sediments deposited during the inter h intervals in ice proximal slope sediments this paper examines this question by an analysis of data from cores on the se baffin slope because the proxies for heinrich events are so massive in scale we removed the major h events h 1 h 2 and h 4 from the records so as to better examine the structure of data in the intervening hemipelagic sediments the period of interest extends between 15 and 40 cal ka interstadial events 2 8 resolution varies with the proxy to between 210 and 700 yrs per sample in hu87033 009 from the lower slope a total of twelve variables for example 18o mass magnetic susceptibility calcite dolomite ratio number of ird 2 mm show a variety of multi millennial oscillations although not all of the same amplitude nor frequency several parameters show little correlation with the gisp2 18o record however a comparison of cie sediment color l from hu87033 009 and hu97048 007 from the upper slope with the gisp2 oxygen isotope record suggests that a substantial correlation exists between the records such changes might be associated with either detrital carbonate content or foraminiferal concentrations analysis suggests however that the first possibility is correct hence suggestive of a glaciological response of the hudson strait ice stream with d o events in the nw labrador sea the sediment records from around h 3 time 30 cal ka show excursions which might be correlative within this event but its amplitude is not unusual compared to events both before and after this reaffirms the argument that h 3 represents a different glaciological response a significant issue discussed in this paper is the inherent ambiguity of correlating records whose errors in the time domain approach that of a dominating periodicity in this case ca 1 5 kyr

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

crustal deformation measurements in central japan determined by a global positioning system fixed point network a global positioning system gps fixed point network has been operating in the kanto and tokai districts of central japan since april 1988 to detect crustal deformation associated with the convergence of the eurasian pacific north american and philippine sea plates and to monitor the deformation cycles of frequent large interplate and intraplate earthquakes this 10 station network established by the national research institute for earth science and disaster prevention nied is the first continuously monitoring network of its kind we determine deformation within the network using two consecutive days of data every 2 weeks for the first 17 months of operations we use a station and orbit relaxation method which relies exclusively on data collected within the nied network except for 1 week of global gps tracking data which is used to determine initial station positions with respect to the global reference frame we detect relative to a station on the eurasian plate in central japan significant westward motion of 28 mm yr of the northern tip of the philippine sea plate which is subducting beneath the eurasian plate at the suruga trough our results support finite element models of collision of the izu block with the eurasian plate based on earthquake focal mechanisms and plate block motions of the japanese archipelago determined from conventional geodetic measurements over the last century we detect southwestward motion of 18 mm yr of the southeastern tip of the eurasian plate confirming expected surface extension of the subducted plate parallel to the suruga trough axis significant vertical uplift with a velocity of 20 mm yr is suggested at a site inland of the tokai district located in the akaishi uplift zone and at a site on hatsushima island in sagami bay the general tendency of vertical movements of the other sites agrees with vertical velocities obtained from 70 years of geodetic leveling and with quaternary vertical displacements determined from geomorphological and other geological evidence we detect no significant crustal motion across the fossa magna tectonic zone in central japan often considered a plate boundary across the tokyo metropolitan area nor across the sagami trough associated with the subduction of the philippine sea plate beneath northeast japan our results demonstrate the power of regionally based continuously monitoring gps networks for obtaining temporally dense measurements of small horizontal and vertical crustal movements across plate boundary zones

a high resolution holocene sediment record from hunafloaall n iceland margin centuryto millennial scale varability since the vedde tephra md99 2269 is a 25 m long core from hunafloaall a deep trough which runs northward towards the shelf break from the narrow neck of land which joins the northwest peninsula of iceland with the main land the core was recovered from the thickest part of an elongate shelf sediment body underlain by glacial diainictons with ages 26 ka bp 3 5 khz profiles indicate the presence of a reflector ri which can be traced over long distances twelve ams radiocarbon dates and the presence of the saksunarvatn tephra which is the origin for the ri reflector at 21 m core depth define a linear depth age relation with an accumulation rate of 200 cm ky the date on the core top is modern x radiographs indicate that the sediments are principally massive bioturbated muds the data were measured at resolutions of between 5 and 40 yr sample our primary data represent aspects of a multisensor track measurements b colour c grain size d sediment properties and e sediment magnetic properties principal component analysis pca was used to simplify the analysis of these five data sets and resulted in nine significant axes compared to over 70 original variables the explained variance on the first axes varied between 47 and 96 these time series were reduced to a common 50 yr sample interval which were then also subject to pca using the resulting pc scores we present three primary axes of environmental variability in hunafloaall that have century scale quasi periodicities and demonstrate that these are highly correlated with specific raw variables we focus on variables linked to changes in grain size and productivity and show regional coherence cores b997 321 and 330 in the coercivity grain size measure armj 20 armj 0 which have a close similarity to the detrended 14 c series this provides a potential link to the vigour of the thermohaline circulation to the north of the iceland shelf in the iceland and greenland seas our data indicate increas

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

high resolution thermal inertia mapping from the mars global surveyor thermal emission spectrometer abstract high resolution thermal inertia mapping results are presented derived from mars global surveyor mgs thermal emission spectrometer tes observations of the surface temperature of mars obtained during the early portion of the mgs mapping mission thermal inertia is the key property controlling the diurnal surface temperature variations and is dependent on the physical character of the top few centimeters of the surface it represents a complex combination of particle size rock abundance exposures of bedrock and degree of induration in this work we describe the derivation of thermal inertia from tes data present global scale analysis and place these results into context with earlier work a global map of nighttime thermal bolometer based thermal inertia is presented at 1 4 per pixel resolution with approximately 63 coverage between 50 s and 70 n latitude global analysis shows a similar pattern of high and low thermal inertia as seen in previous viking low resolution mapping significantly more detail is present in the high resolution tes thermal inertia this detail represents horizontal small scale variability in the nature of the surface correlation with albedo indicates the presence of a previously undiscovered surface unit of moderate to high thermal inertia and intermediate albedo this new unit has a modal peak thermal inertia of 180 250 j m 2 k 1 s 1 2 and a narrow range of albedo near 0 24 the unit covering a significant fraction of the surface typically surrounds the low thermal inertia regions and may comprise a deposit of indurated fine material local 3 km resolution maps are also presented as examples of eolian fluvial and volcanic geology some impact crater rims and intracrater dunes show higher thermal inertias than the surrounding terrain thermal inertia of aeolian deposits such as intracrater dunes may be related to average particle size outflow channels and valleys consistently show higher thermal inertias than the surrounding terrain generally correlations between spatial variations in thermal inertia and geologic features suggest a relationship between the hundred meter scale morphology and the centimeter scale surface layer

global ice volume fluctuations north atlantic ice rafting events and deep ocean circulation changes between 130 and 70 ka multiproxy data from north atlantic deep sea sediment core neap18k provide a detailed record of climate through oxygen isotope stage ois 5 seven distinct large scale episodes of ice rafting c25 c19 were identified between 126 and 70 ka global ice volume reconstructions based on high resolution benthic 18 o records indicate that major ice rafting events were not confined to ice volume maxima at ois 5d and 5b but also occurred during periods of ice sheet growth and disintegration however iceberg discharges were restricted to times when sea levels were 40 65 m below present values ice rafting episode c25 the first large scale cooling of mid atlantic surface waters after the last interglacial occurred during the gradual buildup of continental ice sheets at the ois 5e 5d transition major ice sheet collapses allied to ice rafting events c24 and c21 were associated with rapid sea level increases of 20 and 40 m respectively suborbital climatic fluctuations in the neap18k sedimentary record denoted by prominent 7 5 4 5 and 3 k y cyclicities appear to correlate with both greenland atmospheric temperatures and changes in thermohaline circulation patterns inferred from benthic 13 c values and hence provide clear evidence of a highly interconnected north atlantic climatic regime during ois 5

quaternary and geodetically measured crustal movements in the tokai district central honshu japan geodetic measurements made in this century demonstrate that modern movements correlate well with deformation that has occurred during the past 2 m y both show effects of subduction and of the quaternary collision of izu peninsula with central honshu westward from suruga bay deformation is greatest near the coast decreases markedly towards the uplifting akaishi mountains and then increases again in the conjugate block faulted terranes of chubu district quaternary faults historic earthquakes and the distribution of horizontal shear straining since 1880 all reflect this deformation pattern since 1900 the west coast of suruga bay has undergone secular subsidence horizontal contraction and tilting towards suruga trough all typical of the strain buildup process that occurs landward of subduction zones however futher westward active mountain building is occuring and the akaishi ranges are rising 3 mm a unlike the episodic aseismic uplift of the transverse ranges of southern california movements here have been relatively uniform it seems likely that an increase in the tilt rate of the suruga coast recognized since 1973 is part of a long term readjustment to the great 1944 tonankai earthquake data show that a monotonic increase has occurred since at least 1949 and similar effects are seen adjacent to the 1944 rupture zone over 200 km southwest along the nankai trough

atmospheric changes in north america during the last deglaciation from dune wetland records in the midwestern united states reconstructing moisture conditions during the early retreat of the laurentide ice sheet lis may help define the phase relationship of deglacial conditions and atmospheric changes over north america here we report two sediment successions near the concurrent ice margins in the midwest of the u s a to show that dune formation was active from 17 7 to 14 7 and from 12 8 to 11 8 thousand years ago ka and lowland soils formed at 14 7 and wetland sediments developed from 13 5 to 12 8 ka our results suggest that moisture conditions in the midwestern u s a were inversely phased with those in the southwestern u s a during the heinrich event 1 h1 and younger dryas yd stadials the northern area became drier and southern area became wetter whereas during the bolling allerod b a interstadials the northern area became wetter and southern area became drier this pattern is also observed on phase change levels within the h1 interval in detail from 17 7 to 16 5 ka during the h1b phase major aridity in the midwest corresponded to wet conditions in the southwest u s a from 16 5 to 15 0 ka during the h1a phase climate reversed from dry to wet in the midwest whereas conditions went from wet to dry in the southwest from 15 0 to 14 7 ka during the transition to the bolling allerod t b a phase a return of aridity in the midwest corresponded to a return of humidity in the southwest

sea surface temperature changes in the okhotsk sea and adjacent north pacific during the last glacial maximum and deglaciation abstract we estimated sea surface temperatures ssts in the western okhotsk sea during the last glacial maximum lgm and the last glacial termination from measurements of the alkenone unsaturation index u k 37 the t etra e ther inde x of tetraethers consisting of 86 carbon atoms tex 86 and tex 86 l in piston core sediments which reveal the climate response of this region to different types of forcings tex 86 l is a modification of tex 86 proposed for high latitude ocean regions the tex 86 l derived temperatures were not different from the alkenone derived temperatures from the same and nearby sediment samples during the lgm alkenone derived temperatures in the okhotsk sea were relatively warm these and similarly warm alkenone derived temperatures found at many other sites in the western north pacific may reflect a shift in the season of biomarker production from early summer and autumn to mid summer during the lgm as a result of the expansion of the season of sea ice cover empirical orthogonal function eof analysis of alkenone derived temperatures at 14 sites from the north pacific suggested substantial cooling between 20 and 14 cal kyr bp during the deglaciation at 11 of the sites including 4 sites in the okhotsk sea this dominant eof mode suggests either an overall seasonal bias in alkenone derived temperatures or potential shifts in the haptophyseae production season the second eof mode of variability indicated a deglacial warming trend punctuated by millennial scale cold events associated with reorganizations of the atlantic meridional overturning circulation the sst pattern corresponding to this eof mode is indicative of millennial scale meridional shifts of the axis of the westerly jet which may have affected heat transport across the kuroshio reconstructed temperature changes in particular in the okhotsk sea provide insight into the conditions that modulated the ventilation history of intermediate waters in the north pacific

geology of the melas chasma landing site for the mars exploration rover mission 1 the melas chasma landing site was considered a high priority site for the mars exploration rover mer mission because of the opportunity to land on and study potential layered sedimentary deposits though no longer considered a candidate site because of safety concerns the site remains a scientifically interesting area that provides insight into the geologic history of valles marineris within the landing ellipse are dunes landslide material and unusual blocky deposits the blocky deposits are composed of rounded blocks some of which have meter scale layering and they show evidence of ductile deformation including bending and distortion of coherent blocks around each other the morphologic characteristics of the blocks are unique and they appear to have no terrestrial analogue however the gross morphology of these blocky deposits and their superposition on adjacent wallrock is consistent with the blocks having been transported downslope given the existence of other large mass failures in the area we propose the blocky deposits may also have originated from mass movement events the size of the blocks coupled with the distances they traveled indicates high mobility the distances the blocks were transported and their rounded irregular shapes suggest either water in the source material or deposition in a subaqueous environment the source for the main blocky deposit inside the landing ellipse is considered to be the wallrock to the south while the other two blocky deposits have source regions along the northern canyon walls the southern wallrock of melas chasma contains numerous valleys not seen elsewhere in valles marineris the identification of valley networks along the southern wallrock suggests that a source of water existed below the surface of the plateau and produced the valleys after intersecting the edge of the exposed canyon walls

high outflow channels on mars indicate hesperian recharge at low latitudes and the presence of canyon lakes abstract a number of martian outflow channels were carved by discharges from large dilational fault zones these channels were sourced by groundwater not surface water and when observed on high standing plateaus they provide indicators of elevated paleo groundwater levels we identify three outflow channels of hesperian age that issued from a 750 km long fault zone extending from candor chasma to ganges chasma two of these channels allegheny vallis and walla walla vallis have sources 2500 m above the topographic datum too high to be explained by discharge from a global aquifer that was recharged solely in the south polar region the indicated groundwater levels likely required regional sources of recharge at low latitudes the floodwaters that erupted from ophir cavus to form allegheny vallis encountered two ridges that restricted the flow forming temporary lakes the flow probably breached or overtopped these obstructions quickly catastrophically draining the lakes and carving several scablands after the last obstacle had been breached a single main channel formed that captured all subsequent flow we performed hydrologic analyses of this intermediate phase of the flooding prior to incision of the channel to its present depth using floodwater depths of 30 60 m we calculated flow velocities of 6 15 m s 1 and discharges in the range of 0 7 3 10 6 m 3 s 1 locally higher flow velocities and discharges likely occurred when the transient lakes were drained variable erosion at the channel and scabland crossing of mola pass 10644 suggests that the upper 25 30 m may consist of poorly consolidated surface materials underlain by more cohesive bedrock we infer that an ice covered lake with a surface elevation 2500 m probably existed in eastern candor chasma because this canyon is intersected by the ophir catenae fault system from which allegheny vallis and walla walla vallis originated we introduce a new hydrology concept for mars in which the groundwater system was augmented by recharge from canyon lakes that were formed when water was released by catastrophic melting of former ice sheets in tharsis by effusions of flood basalts this model could help to reconcile the expected presence of a thick cryosphere during the hesperian with the abundant evidence for groundwater as a source for some of the circum chryse outflow channels

climatic variability during the last 90 ka of the southern and northern levantine basin as evident from marine records and speleothems abstract the influence of the northern atlantic and tropical monsoonal systems as recorded by the river nile on the climate variability of the southeastern mediterranean was studied in two cores taken by the r v marion dufresne one core taken se of cyprus representing the northern levantine basin core 9501 980 m water depth and the other located 380 km further south represents the southeastern levantine basin in an area influenced by the river nile plume core 9509 884 m water depth the study was performed at relatively high resolution using several proxies 18o of globigerinoides ruber sediment characteristics and index colour parameters in core sections representing the last 86 ka a low resolution alkenone sea surface temperature record was also measured the time frame in both cores was mostly constrained by wiggle matching with the nearby well dated 18o and 13c record of the soreq cave which is mainly influenced by the eastern mediterranean water vapor the sedimentary record of the southern core is strongly influenced by the river nile contribution throughout the last 86 ka as evidenced by the higher sedimentation rates compared with the northern core 20 cm ka vs 5 cm ka continuously darker sediment colour and higher toc values 0 6 0 9 vs 0 25 wt not including sapropels during sapropels s1 and s3 present in both cores the influence of the river nile became more widespread reaching as far as cyprus yet the influence of the river nile remained stronger in the south as evident by the higher toc values in the southern core throughout the entire 90 ka period and the longer duration of s1 in the southern core an anomalous low 18o interval that is not recorded in western mediterranean occurred between 58 and 49 ka in the levantine basin and is more developed in the northern core this period correlates with d o interstadial 14 and maximum northern hemisphere insolation during the lastglacial cycle suggesting that the warming mainly impacted the northern levant the eastern mediterranean sea and land area was considerably warmer than the western mediterranean throughout the lgm holocene transition and the 18og ruber drop of 4 5 is significantly greater than the 3 shift found for the western mediterranean 18og bulloides both differences reflecting an increased continental effect from the western to eastern mediterranean comparison between the marine and the land 18o records suggests that the origin of rain over the land is composed of mixed signal from the southern and northern levantine basin the study of 18osea land variations demonstrates that various factors have influenced the sea land relationship during the last 90 ka the amount effect has an important influence on rainfall 18o during interglacial periods particularly sapropel periods whereas during glacial periods increased land distances and elevation differences arising from decrease in sea level may have brought about decrease in 18o of rainfall due to rayleigh distillation processes these influences were superimposed on those of sea surface water 18o changes brought about by continental ice melting and the strong effects felt in the southern levantine basin of the high river nile input during periods of enhanced monsoonal activity

alkenones as paleoceanographic proxies 1 alkenone derived estimates of temperature and co2 are contributing to our understanding of earth s climate history in order to increase confidence in alkenone based climate proxies we recommend the following actions first the sedimentary component or fraction containing alkenones should be identified in order to assess the impact of horizontal advection and vertical mixing on alkenone derived temperature and co2 estimates second differential mixing rates of alkenone containing particles and sand sized foraminifera should be quantified by independent dating of the two phases until that is accomplished apparent temporal offsets of climate proxies in the two phases should be interpreted cautiously third the stability of the unsaturation ratio and carbon isotopic compositions of alkenones during all phases of diagenesis should be confirmed both field and laboratory observations are required fourth future alkenone investigations should be coupled with other paleoclimate proxy measurements at high deposition rate sites in a variety of oceanographic settings in upwelling regions and in the vicinity of river plumes salinity and nutrient proxies should be measured since changes in these parameters may affect alkenone biosynthesis

a 370 ka paleoceanographic record from the hess rise central north pacific ocean and an indistinct kuroshio extension abstract a 5 m long core np36 collected from the hess rise in the central north pacific ocean 34 11 7 n 179 15 4 e water depth 2664 m was analyzed for benthic and planktonic foraminifera this core yields a continuous record for the last ca 370 000 years according to the oxygen isotope stratigraphy cross spectral analysis of down core variations in planktonic 18o values correlates well with the specmap reference scale allowing recognition of marine isotope stages mis down to mis 10 and the 18o variations coincide well with the changes in sea surface temperature derived using the modern analogue technique time series analyses of mass accumulation rates mar of planktonic and benthic foraminifera were also performed along with analysis of variations in faunal composition mar of planktonic foraminifera display maxima during glacial periods which together with coincident changes in lightness l of sediment measured with the spectrophotometer strongly suggests increasing flux of eolian dust to the hess rise due to strengthened westerly winds however mar of benthic foraminifera including epistominella exigua a common typical phytodetritus feeder also display highest increases during some interglacial periods i e mis 5 and 7 the benthic mar maxima are thought to reflect variations in consumption patterns between benthic and planktonic species a proposed hypothesis that vigorous grazing of phytoplanktons occurred during glacial periods reducing the flux of phytodetritus to the sea floor in turn impacting and limiting production of benthic foraminifera with the opposite effect prevailing during interglacial periods down core variations in right coiling neogloboquadrina pachyderma abundance and the composition of planktonic foraminiferal faunas indicate the subarctic front did not shift southward over the study site during the past 370 000 years alternatively variations in faunal composition indicate that subtropical water prevailed in the study area throughout this period no clear faunal evidence of the presence of the kuroshio extension was found in core np36 reflecting the loss of heat and tropical faunal elements from this water mass as it flowed eastward during late quaternary climatic maxima and minima

provenance age and environment of mid wisconsinan slackwater lake sediment in the st louis metro east area usa abstract valleys tributary to the mississippi river contain fossiliferous slackwater lake sediment equality formation deposited in response to aggradation of the mississippi river valley during the last glaciation in the st louis metro east area the lower part of the equality formation is primarily laminated fossiliferous silt and clay deposited from about 44 150 to 24 310 14c yr b p the upper equality formation is primarily very fine sand to silt deposited from about 21 200 to 17 000 14c yr b p among the four cores that sample this succession in the st louis metro east area core mnk 3 38 64en 90 01ew was selected for detailed study three sources are distinguished by the following characteristics 1 gray smectite quartz se rich feldspar poor material of the des moines wadena and james lobes 2 reddish brown kaolinite cu fe rich sediment of the superior and rainy lobes and 3 brown illite dolomite sr rich sediment of the lake michigan and green bay lobes the earliest sediments 44 150 to 41 700 14c yr b p were derived from the central and western provenances and are chronocorrelative with the lower roxana silt a hiatus occurred from about 41 700 to 29 030 14c yr b p when much of the middle roxana silt meadow member was deposited on adjacent uplands the youngest sediment includes evidence of heightened activity of the superior lobe at about 29 000 14c yr b p the lake michigan and green bay lobes from about 25 000 to 24 000 14c yr b p and the wadena des moines james lobes at about 21 000 14c yr b p

geological context of water altered minerals in valles marineris mars 1 greater than 15 000 km2 of the layered deposits within valles marineris are associated with water altered minerals yet their origin and history of alteration remain a mystery there are numerous competing hypotheses for the formation of the interior layered deposits including aeolian lacustrine and volcanic recent orbiter spectroscopic data have indicated that water has played a role in their geological history thermal emission spectrometer tes measurements have revealed significant crystalline hematite bearing deposits within valles marineris typically related to interior layered deposits these hematite deposits found with a wide range of albedo values are associated with relatively steep bedrock exposures but can also be seen downslope on flat surfaces where they may be a lag deposit more recently observatoire la mineralogie l eau les glaces et l activite omega data have shown hydrated sulfates covering more than 13 000 km2 area of valles marineris sulfates are found in numerous topographic settings and geological units but are typically located along the flanks of interior layered deposits and nearby low lying floor units here we study the detailed morphologies of hematite and sulfate bearing units such as mantled wall units mass wasting blocky deposits massive floor deposits and tectonically altered floor units all of these terrains have diverse erosional styles and varied crater populations in both hematite and sulfate bearing units occasionally found in conjunction with one another formation processes require contributions from water the results indicate a wide range of diversity within an individual mineral class between mineral classes and also among morphological types the diversity of geological settings and properties suggest that any single unified formation mechanism is improbable

what level of resolution is attainable in a deep sea core results of a spectrophotometer study a minolta cm 2022 spectrophotometer has been used to characterize downcore fluctuations in sediment lightness and color in core neap15k a 7 m core collected from the northeast atlantic ocean high resolution data series measured using a 4 mm diameter measurement spot and a 1 cm sampling interval were generated along two independent tracks down the core to investigate the statistical significance of fluctuations across the 2 20 cm depth range this small scale variability is characterized by abrupt changes in the lightness and color of the sediment that are several orders of magnitude greater than the instrumental precision our results establish that significant information is preserved at the 1 cm scale in spite of bioturbation effects these findings demonstrate that high resolution studies using conventional paleoclimatic proxies have the potential to recover meaningful century scale climate records in regions of the ocean where sedimentation rates exceed 10 cm per thousand years the coherency of these downcore records also implies that the spectrophotometer is a powerful instrument for establishing precise centimeter scale stratigraphic correlations between cores

north western alps holocene paleohydrology recorded by flooding activity in lake le bourget france abstract a 14 m long piston core was retrieved from lake le bourget nw alps france in order to provide a continuous record of flooding events of the rhone river during the holocene the selection of the coring site was based on high resolution seismic profiling in an area with limited mass wasting deposits and accumulated proximal rhone river inter and underflow deposits the age depth model of this core is based on i 14 ams radiocarbon dates ii radionuclide dating 137cs and iii the identification of historical data flood events eutrophication of the lake the sedimentary record dates back to 9400 cal bp and includes a thin mass wasting event deposited around 4500 cal bp a multi proxy approach was used to track the evolution and origin of clastic sedimentation during the holocene in order to identify periods of higher hydrological activity in the catchment area spectrophotometry was used to detect fluctuations in clastic supply and the study of clay minerals especially the illite crystallinity index allowed locating the main source area of fine grained clastic particles settling at the lake after flood events this dataset highlights up to 12 periods of more intense flooding events over the last 9400 years in lake le bourget and shows that the main source area of clastic particles during this period is the upper part of the arve river drainage basin this part of the catchment area drains several large glaciers from the mont blanc massif and fluctuations in rhone river flood supply in lake le bourget is interpreted as resulting essentially from mont blanc glacier activity during the holocene the comparison of clastic sedimentation in lake le bourget with periods of increasing land use and periods of alpine glacier and mid european lake level fluctuations suggest that the core ldb04 clastic record in lake le bourget is a continuous proxy of the holocene hydrological history of the nw alps

spectrophotometer analysis of holocene sediments from an anoxic fjord saanich inlet british columbia canada abstract a borehole core through the holocene sediments of saanich inlet british columbia canada was analyzed using high resolution spectrophotometry to determine whether spectral signal variations can be used as environmental climatic proxies the effects of post drilling oxidation and water loss on the core sample were assessed by comparing spectral measurements taken onboard the research ship immediately after the core was opened with shore based measurements taken one year later for saanich inlet sediments the shore based measurements provided more reliable indications of the degree of basin anoxia our spectral analyses allowed us to identify all the major features of the saanich inlet sediment sequence mazama ash and fraser river drainage stratigraphic markers oxygenation state of the basin by using the first derivative value at 675 nm as a proxy for changes in organic matter content and the colorimetric parameter b as an indicator of diatom content we were able to recognize changes in terrestrially derived organic matter om and diatom concentrations in the sediment we suggest that these variations are due to changes in upwelling intensity and fluctuations in sea level during the holocene our results confirm the potential value of spectrophotometry in identifying sediment composition and in reconstructing paleoenvironments

new techniques in sediment core analysis an introduction marine sediment cores are the fundamental data source for information on seabed character depositional history and environmental change they provide raw data for a wide range of research including studies of global climate change palaeoceanography slope stability oil exploration pollution assessment and control and sea floor surveys for laying cables pipelines and siting of sea floor structures during the last three decades a varied suite of new technologies have been developed to analyse cores often non destructively to produce high quality closely spaced co located downcore measurements characterizing sediment physical properties geochemistry and composition in unprecedented detail distributions of a variety of palaeoenvironmentally significant proxies can now be logged at decadal and in some cases even annual or subannual scales allowing detailed insights into the history of climate and associated environmental change these advances have had a profound effect on many aspects of the earth sciences particularly palaeoceanography in this paper we review recent advances in analytical and logging technology and their application to the analysis of sediment cores developments in providing access to core data and associated datasets and data mining technology in order to integrate and interpret new and legacy datasets within the wider context of sea floor studies are also discussed despite the great advances in this field however challenges remain particularly in the development of standard measurement and calibration methodologies and in the development of data analysis methods new data visualization tools and techniques need to be developed to optimize the interpretation process and maximize scientific value amplified collaboration environments and tools are needed in order to capitalize on our analysis and interpretation capability of large multi parameter datasets sophisticated yet simple to use searchable internet databases with universal access and secure long term funding and data products resulting in user defined data mining query and display so far pioneered in the usa and australia provide robust models for efficient and effective core data stewardship

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

consequences of stress changes following the 1891 nobi earthquake japan abstract great earthquakes along the philippine sea interplate boundary central honshu usually rupture a large portion of the nankai trough and suruga trough however the 1944 tonankai and 1946 nankaido earthquakes the most recent great philippine sea events did not rupture the suruga trough mogi proposed that strain release from the 1891 nobi earthquake is responsible for the apparently premature northeast termination of the 1944 rupture zone using a recently derived fault model of the 1891 earthquake combined with a suitable rheological model of central honshu we quantify both the inland and offshore consequences of the nobi earthquake north of the median tectonic line the co seismic plus postseismic stress changes of the nobi earthquake promoted the failure of faults which subsequently ruptured in the decades following 1891 in contrast along the philippine sea interplate boundary the co seismic plus postseismic strain release of the nobi earthquake during the decades following 1891 has delayed the anticipated tokai earthquake by at least 20 yr

the importance of both geological and pedological processes in control of grain size and sedimentation rates in peoria loess abstract the loess paleosol succession in the peoria loess in southern illinois is characterized as alternating loess layers and weathering bands known as paleosol a horizons the fast loess accumulation during the late wisconsin glaciation interacted with the incipient pedogenesis and caused unclear boundaries of loess paleosol alternations in soil horizonation and mineralogy parameters of grain size distribution sedimentation rate matrix carbonate content and diffuse reflectance i e soil colors and iron oxides are used in this paper to discuss the geological and pedological influences for the peoria loess in keller farm section in southern illinois the multi proxy analysis revealed that many paleosol a horizons defined by the diffuse reflectance variability contain finer grained materials with a relatively higher sedimentation rate it suggests that glaciofluvial sediments were available in the source areas for uploading eolian dust during the temporary ice sheet retreats the denser vegetation and wetter surface soils on the loess deposit area could increase the dust trapping efficiency and caused a greater accumulation rate of loess deposits the coarser grained materials and slower sedimentation rate are often found in loess layers it suggests that strong surface winds transported the coarser grained materials from local dust sources and sparse vegetation and dry surface soils reduced the dust trapping efficiency during the ice sheet readvance the strong interactions between the geological and pedological processes played an important role on the loess paleosol alternations in southern illinois during the late wisconsin glaciation

strainmeters and tiltmeters despite steady effort over the last century continuously recording tiltmeters and strainmeters have not yet been successful except for earth tide measurements this article reviews the techniques and instrument designs that have been developed in this field the continuous measurement of true tectonic motions which have rates of 10 14 s 1 requires extremely high instrument stability but more rapid motions tides and seismic waves apart are even smaller and not much more easily detectable much past effort has been spent improving the transducers used in these instruments which usually measure small displacements the commonest choices are optical the most accurate capacitive the most sensitive and inductive the most rugged nowadays building a transducer is the easiest part a much harder task equally important to a good design is attaching the instrument to the ground so that it can detect the signal wanted this part of the design includes choosing a location a large underground opening is thermally stable but distorting a surface installation is easy to build but noisy because of soil weathering and a borehole is inaccessible to weather but also to the operator all such installations and indeed the whole field of strain and tilt measurement of course rely on the assumption that the deformations of interest can be measured over baselengths of a few hundred meters or less this is true for tides and seismic waves but unproven for tectonic motions appropriate attachment techniques differ for each location and many mundane details such as cementing techniques for borehole instruments remain to be worked out the goal of measuring tectonic and tidal tilt has created many tiltmeter designs most are relatively small instruments that use some form of pendulum or bubble level a few use a liquid surface to measure tilts over a long baseline repeated experience has shown the latter type when well built to be superior to the former proving end monument motions to be a dominant source of noise the same appears to hold true for strainmeters the best results coming from long base laser instruments though strainmeters using rigid or flexible material length standards are useful for special purposes and borehole instruments show promise because achieving a good design has been so difficult it is important to select the goals an instrument must meet and be prepared to compromise on others the difficulty of validating results from this type of instrument makes comparison tests essential such tests as have been made so far show that good results cannot be gotten at low cost or without careful attention to details

evidence for massive discharges of icebergs into the north atlantic ocean during the last glacial period sediments in the north atlantic ocean contain a series of layers that are rich in ice rafted debris and unusually poor in foraminifera1 here we present evidence that the most recent six of these heinrich layers deposited between 14 000 and 70 000 years ago record marked decreases in sea surface temperature and salinity decreases in the flux of planktonic foraminifera to the sediments and short lived massive discharges of icebergs originating in eastern canada the path of the icebergs clearly marked by the presence of ice rafted detrital carbonate can be traced for more than 3 000 km a remarkable distance attesting to extreme cooling of surface waters and enormous amounts of drifting ice the cause of these extreme events is puzzling they may reflect repeated rapid advances of the laurentide ice sheet perhaps associated with reductions in air temperatures yet temperature records from greenland ice cores appear to exhibit only a weak corresponding signal moreover the 5 10 000 yr intervals between the events are inconsistent with milankovitch orbital periodicities raising the question of what the ultimate cause of the postulated cooling may have been

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

sedimentary record of rapid climatic variability in the north atlantic ocean during the last glacial cycle comparisons between a greenland ice core isotopic record and marine sediment grey level records of the north atlantic ocean show that rapid temperature variations witnessed by the ice core dansgaard oeschger events during the last glacial period can also be detected in marine sediments this shows that the resolution obtained in marine cores can be sufficiently high to record rapid climatic fluctuations several spectral analyses of those grey level marine records consistently indicate that significative fluctuations of the climatic response exist with periodicities of 5 to 1 kyr in addition to orbital forcing these high frequencies are close to those predicted by various dynamic ocean models

present day vertical deformation of the cascadia margin pacific northwest united states we estimate present day uplift rates along the cascadia subduction zone in california oregon and washington in the pacific northwest united states by utilizing repeated leveling surveys and tide gauge records these two independent data sets give similar profiles for latitudinal variation of contemporary uplift rates along the coast uplift rates are extended inland through east west leveling lines that connect the north south line along the coast to the north south line along the inland valleys just west of the cascades the results are summarized as a contour map of present day uplift rates for the western pacific northwest we find that rates of present day uplift vary latitudinally along the coast and inland valleys as well as longitudinally along transects connecting the coast to the inland valleys long term tidal records of neah bay astoria and crescent city indicate uplift of land relative to sea level of 1 6 0 2 0 0 0 2 and 0 9 0 2 mm yr respectively 1 standard error unlike previous estimates of relative sea level change at astoria we adjust for discharge effects of the columbia river including human management influences after approximating an absolute framework by using 1 8 0 1 mm yr to compensate for global sea level rise results indicate that much of the western pacific northwest is rising at rates between 0 and 5 mm yr the most rapid uplift rates are near the coast particularly near the olympic peninsula the mouth of the columbia river cape blanco and cape mendocino two axes of uplift are identified one trends northeast from the southwest oregon coast and the other trends south southeasterly from the olympic peninsula to the columbia river the puget sound vicinity and a small east west region from the north central oregon coast to the inland willamette valley are subsiding at rates up to 1 mm yr we interpret the overall pattern of rapid present day uplift to be generated by interseismic strain accumulation in the subduction zone this interseismic elastic strain accumulation implies significant seismic hazard

erosion under climate and human pressures an alpine lake sediment perspective we review the scientific efforts over the last decades to reconstruct erosion from continuous alpine lake sediment records we focused both on methodological issues showing the growing importance of non destructive high resolution approaches xrf core scanner as well as progresses in the understanding of processes leading to the creation of an erosion signal in lakes we distinguish continuous records from event records both provide complementary information but need to be studied with different approaches continuous regionally relevant records proved to be particularly pertinent to document regional erosion patterns throughout the holocene in particular applying the source to sink approach event based approaches demonstrated and took advantage of the strong non linearity of sediment transport in high altitude catchment areas this led to flood frequency and intensity reconstructions highlighting the influence of climate change upon flood dynamics in the mountain the combination of different record types both in terms of location high vs low elevation sedimentology high vs low terrigenous contribution and significance local vs regional is one of the main outputs of this paper it allows the establishment of comprehensive histories of nw french alps erosion but also and consequently soil dynamics and hydrological patterns throughout the holocene we also discuss the influence of glacier dynamics one of the major agents of erosion in the alps a major feature is the growing human influence upon erosion at a local scale since at least the middle of the bronze age 3500 cal bp however and according to the regional record from lake bourget only few periods of rising erosion at local scales generated a regional record that can be discriminated from wetter climatic periods among them the period between 200 bce and 400 ad appeared to be marked by a generalised rise in human triggered erosion at local scales in the northern french alps this review highlights the importance of modern high resolution and interdisciplinary studies of lake sediments in order to better understand the complex relationships between humans climate and the earth system in general we strongly argue that regional integration of data is now required to move a step further such an integration is easier with cost and time effective methods as well as after a better definition of approaches and their limits this should lead to a stronger collaboration between paleo data producers and modellers in the near future

chemical components of the martian soil melt degassing hydrothermal alteration and chondritic debris on the basis of measurements by the viking and soviet phobos missions the fine grained surficial drift material on mars is enriched in moderately volatile and mobile elements such as s cl k and br the compounds of these elements may amount to as much as 16 wt of the soil while the bulk of the soil appears to consist primarily of crustal material whose composition is similar to that of the basaltic mars meteorites clark 1993 three possible geochemical sources melt degassing hydrothermal alteration and accretion of chondritic material may have contributed to the enrichments we have evaluated possible chemical signatures for these sources by examining the relative abundances of chemical elements in the different components to the measured k abundance in the mars soil and have identified characteristic elements for each component the relative abundances of mobile elements in the different components are much less variable than their absolute abundances which strongly depend on conditions such as temperature and water composition the volatility controlled elemental signature of the melt degassing process includes enrichments of zn mo cd ba and w relative to the elemental abundances in the other components and martian meteorites hydrothermal alteration of minerals and glass controlled by low temperature solubility makes up a second component with a characteristic lithium enrichment signature a chondritic component is enriched in siderophile and chalcophile elements including ni compared to material derived from the martian mantle which was depleted in siderophile elements due to core formation unfortunately the existing data for the mars soil do not include any of these key signature elements and the uncertainties for the viking analyses could allow large amounts of each of these elements the mars pathfinder inorganic analysis experiment and the 2001 orbital gamma ray experiment have the potential to determine some of these characteristic elements and to reveal the possible contributions to the soil the enriched components of the soil especially cd and pb could also be a potential hazard for future martian explorers who will be exposed to the dust carried into their habitats on their space suits

mineralogic and compositional properties of martian soil and dust results from mars pathfinder mars pathfinder obtained multispectral elemental magnetic and physical measurements of soil and dust at the sagan memorial station during the course of its 83 sol mission we describe initial results from these measurements concentrating on multispectral and elemental data and use these data along with previous viking snc meteorite and telescopic results to help constrain the origin and evolution of martian soil and dust we find that soils and dust can be divided into at least eight distinct spectral units based on parameterization of imager for mars pathfinder imp 400 to 1000 nm multispectral images the most distinctive spectral parameters for soils and dust are the reflectivity in the red the red blue reflectivity ratio the near ir spectral slope and the strength of the 800 to 1000 nm absorption feature most of the pathfinder spectra are consistent with the presence of poorly crystalline or nanophase ferric oxide s sometimes mixed with small but varying degrees of well crystalline ferric and ferrous phases darker soil units appear to be coarser grained compacted and or mixed with a larger amount of dark ferrous materials relative to bright soils nanophase goethite akaganeite schwertmannite and maghemite are leading candidates for the origin of the absorption centered near 900 nm in imp spectra the ferrous component in the soil cannot be well constrained based on imp data alpha proton x ray spectrometer apxs measurements of six soil units show little variability within the landing site and show remarkable overall similarity to the average viking derived soil elemental composition differences exist between viking and pathfinder soils however including significantly higher s and cl abundances and lower si abundances in viking soils and the lack of a correlation between ti and fe in pathfinder soils no significant linear correlations were observed between imp spectral properties and apxs elemental chemistry attempts at constraining the mineralogy of soils and dust using normative calculations involving mixtures of smectites and silicate and oxide minerals did not yield physically acceptable solutions we attempted to use the pathfinder results to constrain a number of putative soil and dust formation scenarios including palagonitization and acid fog weathering while the pathfinder soils cannot be chemically linked to the pathfinder rocks by palagonitization this study and mcsween et al 1999 suggest that palagonitic alteration of a martian basaltic rock plus mixture with a minor component of locally derived andesitic rock fragments could be consistent with the observed soil apxs and imp properties

the chronology of the last deglaciation implications to the cause of the younger dryas event it has long been recognized that the transition from the last glacial to the present interglacial was punctuated by a brief and intense return to cold conditions this extraordinary event referred to by european palynologists as the younger dryas was centered in the northern atlantic basin evidence is accumulating that it may have been initiated and terminated by changes in the mode of operation of the northern atlantic ocean further it appears that these mode changes may have been triggered by diversions of glacial meltwater between the mississippi river and the st lawrence river drainage systems we report here accelerator mass spectrometry ams radiocarbon results on two strategically located deep sea cores one provides a chronology for surface water temperatures in the northern atlantic and the other for the meltwater discharge from the mississippi river our objective in obtaining these results was to strengthen our ability to correlate the air temperature history for the northern atlantic basin with the meltwater history for the laurentian ice sheet

holocene hydrological events and human induced environmental changes reflected in a southeastern mediterranean fluvial archive abstract the chronostratigraphy of an eastern mediterranean holocene fluvial sequence reflects global trends climate and sea level local modulations hydrological regime and storm surges and anthropogenic impact two continuous cores retrieved from the tanninim stream estuary on the carmel coast of israel are dated by optically stimulated luminescence osl to span the holocene the sedimentology and faunal assemblages are analyzed for reconstructing environmental conditions despite time gaps recognized in the fluvial successions three main depositional periods provide distinctive archives capturing natural and anthropogenic centennial to millennial changes alternations between enhanced and reduced fluvial activity associated with humid and dry climate conditions characterized the early to mid holocene fluvial record between about 7 8 and 5 7 ka and may match eastern mediterranean climate records the first humid phase from 8 to 6 ka features organic rich fine sediments and proliferating brackish ostracods foraminifera and molluscs the appearance of this biofacies indicates the initiation of seepage from the yarkon tanninim aquifer through the brackish oligohaline enot timsah springs the advancing coastline due to sea level rise starting about 5 8 ka resulted in an increasing supply of quartz sands and marine transported foraminifera relatively fast accumulation of organic rich fine grained sediments with enhanced preservation of brackish fauna during the late holocene is probably associated with maintenance of the tanninim dams during the early arab period 7th 8th centuries ce the last century has been characterized by accelerated sedimentation rates that may be associated with reduced vegetation cover due to modern human activity and by deposition by a high energy surge event this study demonstrates that the lower part of a semi arid southeastern mediterranean estuary responds to periods of climatic and sea level change on a regional scale and to human impact and abrupt past hydrological events on a local scale

a mossbauer investigation of iron rich terrestrial hydrothermal vent systems lessons for mars exploration hydrothermal spring systems may well have been present on early mars and could have served as a habitat for primitive life the integrated instrument suite of the athena rover has as a component on the robotic arm a mossbauer spectrometer in the context of future mars exploration we present results of mossbauer analysis of a suite of samples from an iron rich thermal spring in the chocolate pots area of yellowstone national park ynp and from obsidian pool ynp and manitou springs colorado we have found that mossbauer spectroscopy can discriminate among the iron bearing minerals in our samples those near the vent and on the surface are identified as ferrihydrite an amorphous ferric mineraloid subsurface samples collected from cores which are likely to have undergone inorganic and or biologically mediated alteration diagenesis exhibit spectral signatures that include nontronite a smectite clay hematite alpha fe2o3 small particle nanophase goethite alpha feooh and siderite feco3 we find for iron minerals that mossbauer spectroscopy is at least as efficient in identification as x ray diffraction this observation is important from an exploration standpoint as a planetary surface instrument mossbauer spectroscopy can yield high quality spectral data without sample preparation backscatter mode we have also used field emission scanning electron microscopy fesem in conjunction with energy dispersive x ray edx fluorescence spectroscopy to characterize the microbiological component of surface sinters and the relation between the microbiological and the mineralogical framework evidence is presented that the minerals found in these deposits can have multi billion year residence times and thus may have survived their possible production in a putative early martian hot spring up to the present day examples include the nanophase property and the mossbauer signature for siderite which has been identified in a 2 09 billion year old hematite rich chert stromatolite our research demonstrates that in situ mossbauer spectroscopy can help determine whether hydrothermal mineral deposits exist on mars which is significant for exobiology because of the issue of whether that world ever had conditions conductive to the origin of life as a useful tool for selection of samples suitable for transport to earth mossbauer spectroscopy will not only serve geological interests but will also have potential for exopaleontology

reconstructing the response of c3 and c4 plants to decadal scale climate change during the late pleistocene in southern illinois using isotopic analyses of calcified rootlets abstract the 13c and 18o values of well preserved carbonate rhizoliths crs provide detailed insights into changes in the abundance of c3 and c4 plants in response to approximately decadal scale changes in growing season climate we performed stable isotope analyses on 35 40 crs sampled at 1 cm intervals from an 18 cm thick paleosol formed in southern illinois during wisconsin interstadial 2 minimum 13c values show little variation with depth whereas maximum values vary dramatically and average values show noticeable variability maximum 18o values vary less than the minimum 18o values these findings indicate that a diverse and stable c3 flora with a limited number of c4 grass species prevailed during this interval and suggest that the maximum growing season temperatures were relatively stable but minimum growing season temperatures varied considerably two general patterns characterize the relationships between the 13c and 18o values obtained from the 1 cm samples in some cases low 13c values correspond to low 18o values and high 13c values correspond to high 18o values suggesting that cooler growing season temperatures favored c3 and warmer growing season temperatures favored c4 plants in other cases low 13c values correspond to high 18o values likely suggesting that wetter growing season conditions were favorable to c3 plants the high density of well preserved crs in this paleosol provides a unique opportunity to study detailed ecological responses to high resolution variability in growing season climate

a sedimentary record of holocene surface runoff events and earthquake activity from lake iseo southern alps italy this study presents a record of holocene surface runoff events and several large earthquakes preserved in the sediments of pre alpine lake iseo northern italy a combination of high resolution seismic surveying detailed sediment microfacies analysis non destructive core scanning techniques and ams 14c dating of terrestrial macrofossils was used to detect and date these events based on this approach our data shed light on past seismic activity in the vicinity of lake iseo and the influence of climate variability and human impact on allochthonous detrital matter flux into the lake the 19 m long investigated sediment sequence of faintly layered lake marl contains frequent centimetre to decimetre scale sandy silty detrital layers during the early to mid holocene these small scale detrital layers reflecting sediment supply by extreme surface runoff events reveal a distinct centennial scale recurrence pattern this is in accordance with regional lake level highstands and minima in solar activity and thus apparently mainly climate controlled after c 4200 cal yr bp intervals of high detrital flux occasionally also correlate with periods of enhanced human settlement activity in consequence deposition of small scale detrital layers during the late holocene apparently reflects a rather complex interplay between climatic and anthropogenic influences on catchment erosion processes besides the small scale detrital layers five up to 2 40 m thick large scale detrital event layers composed of basal mass wasting deposits overlain by large scale turbidites were identified which are supposed to be triggered by strong earthquakes the uppermost large scale event layer can be correlated to a documented mw 6 0 earthquake in ad 1222 in brescia the four other large scale event layers are supposed to correspond to previously undocumented local earthquakes these occurred around 350 bc 570 bc 2540 bc and 6210 bc and most probably also reached magnitudes in the order of mw 5 0 6 5