remote sensing estimates of glacier mass balances in the himachal pradesh western himalaya india abstract although they correspond to an important fraction of the total area of mountain glaciers 33 000 km2 out of 546 000 km2 himalayan glaciers and their mass balance are poorly sampled for example between 1977 and 1999 the average area surveyed each year on the field was 6 8 km2 only no direct mass balance measurement is available after 1999 to contribute to fill this gap we use remote sensing data to monitor glacier elevation changes and mass balances in the spiti lahaul region 32 2 n 77 6 e himachal pradesh western himalaya india our measurements are obtained by comparing a 2004 digital elevation model dem to the 2000 srtm shuttle radar topographic mission topography the 2004 dem is derived from two spot5 satellite optical images without any ground control points this is achieved thanks to the good on board geolocation of spot5 scenes and using srtm elevations as a reference on the ice free zones before comparison on glaciers the two dems are analyzed on the stable areas surrounding the glaciers where no elevation change is expected two different biases are detected a long wavelength bias affects the spot5 dem and is correlated to an anomaly in the roll of the spot5 satellite a bias is also observed as a function of altitude and is attributed to the srtm dataset both biases are modeled and removed to permit unbiased comparison of the two dem on the 915 km2 ice covered area digitized from an aster image on most glaciers a clear thinning is measured at low elevations even on debris covered tongues between 1999 and 2004 we obtain an overall specific mass balance of 0 7 to 0 85 m a water equivalent depending on the density we use for the lost or gained material in the accumulation zone this rate of ice loss is twice higher than the long term 1977 to 1999 mass balance record for himalaya indicating an increase in the pace of glacier wastage to assess whether these ice losses are size dependant all glaciers were classified into three samples according to their areal extent all three samples show ice loss the loss being higher for glaciers larger than 30 km2 in the case of the benchmark chhota shigri glacier a good agreement is found between our satellite observations and the mass balances measured on the field during hydrological years 2002 2003 and 2003 2004 future studies using a similar methodology could determine whether similar ice losses have occurred in other parts of the himalaya and may allow evaluation of the contribution of this mountain range to ongoing sea level rise

trace and minor elements in galena a reconnaissance la icp ms study minor and trace elements can substitute into the crystal lattice of galena at various concentrations in situ la icp ms analysis and trace element mapping of a range of galena specimens from different deposit types are used to obtain minor trace element data aimed at achieving insight into factors that control minor trace element partitioning the previously recognized coupled substitution ag bi sb 3 2pb2 is confirmed however the poorer correlation between ag and bi sb when the latter elements are present at high concentrations 2000 ppm suggests that site vacancies may come into play 2 bi sb 3 3pb2 galena is the primary host of tl in all mapped mineral assemblages along with cu tl is likely incorporated into galena via the coupled substitution ag cu tl bi sb 3 2pb2 tin can reach significant concentrations in galena 500 ppm cd and minor hg can be incorporated into galena the simple isovalent substitution cd hg 2 pb2 is inferred this paper shows for the first time oscillatory and sector compositional zoning of minor trace elements ag sb bi se te tl in galena from two epithermal ores zoning is attributed to slow crystal growth into open spaces within the vein at relatively low temperatures the present data show that galena can host a broader range of elements than previously recognized for many measured elements the data sets generated display predictable partitioning patterns between galena and coexisting minerals which may be dependent on temperature or other factors trace element concentrations in galena and their grain scale distributions may also have potential in the identification of spatial and or temporal trends within individual metallogenic belts and as markers of ore formation processes in deposits that have undergone superimposed metamorphism and deformation galena trace element geochemistry may also display potential to be used as a trace minor element vector approach in mineral exploration notably for recognition of proximal to distal trends within a given ore system

the late middle palaeolithic in southwest france new tl dates for the sequence of pech de l aze iv the relative and numerical chronological position of the technological and typological variants of the mousterian in southwest france has been the subject of debate for over fifty years since the advent of both esr and tl dating methods in the 1980s a database of chronometric dates for a growing number of sites has been steadily accumulating a recent summary by guibert et al appears to show a complex pattern of broadly overlapping mousterian variants in the late middle palaeolithic and has led some to conclude that bordes initial interpretation of these variants as distinct cultural groups was essentially correct this paper adds to this database with new thermoluminescence dates from pech de l aze iv this site originally excavated by bordes in the 1970s contains a deep sequence of mousterian assemblages which express considerable technological and typological variability and which are associated with well preserved faunal remains excavations were undertaken from 2000 to 2003 in part to gain a better understanding of the geological context of the assemblages and also to obtain chronometric data in this paper new tl dates for the levels 3b 4c 5a and 8 are presented the deepest of these the typical mousterian of layer 8 is placed in marine isotope stage mis 5c another typical mousterian industry from level 5a dates to the transition from mis 5 to mis 4 level 4c which is rich in scrapers is placed in mis 4 while the mousterian of acheulian tradition is attributed to mis 3 at a local scale these new dates allow for the integration of the pech de l aze iv sequence with chronometric dates available for the nearby sites of pech de l aze i and ii and at a more regional scale they provide additional data points from the more poorly dated late interglacial and early mis 4 period these dates are in line with the emerging pattern suggesting that the mousterian variants as they are defined overlap considerably in time and call into question their interpretation as a succession of chronological units while a correlation with climate change of the technological units is not clear either

textures trace elements and pb isotopes of sulfides from the haopinggou vein deposit southern north china craton implications for discrete au and ag pb zn mineralization the haopinggou deposit in the xiong ershan district southern margin of the north china craton comprises numerous au and ag pb zn veins hosted in metamorphic rocks of the late archean to early paleoproterozoic taihua group two stages of mineralization have been recognized stage 1 pyrite quartz veins and stage 2 pb zn sulfide veins some pyrite quartz veins are surrounded or cut by pb zn sulfide veins others occur as independent veins six generations of pyrite have been identified at haopinggou py1 to py3 in stage 1 and py4 to py6 in stage 2 pyrites from stage 1 are enriched in au as co ni and bi whereas stage 2 pyrites contain higher ag pb zn sn and sb invisible au mostly occurs as lattice bound gold in py2 up to 92 ppm au and py3 up to 127 ppm au and has a close relationship with as native au grains are also present in py3 and likely resulted from mobilization and reprecipitation of the invisible au previously locked in the precursor pyrite this view is supported by extensive plastic deformation in stage 1 pyrite as revealed by electron backscatter diffraction analysis in stage 2 ag is mostly present as lattice bound silver closely associated with sb in galena up to 798 ppm ag a variety of silver minerals are also present as inclusions within galena or as interstitial grains these silver minerals were likely formed via ag cu exchange reaction between tetrahedrite and galena or represent exsolution from galena due to a temperature decrease pb isotopic compositions differ remarkably between stage 1 and stage 2 sulfides indicating different sources of lead pb in stage 2 pb zn sulfide veins is consistent with the haopinggou porphyry close to the veins the field textural compositional and lead isotopic data led us to conclude that the early gold bearing pyrite quartz veins and late silver bearing pb zn sulfide veins likely formed from distinct fluid systems related to discrete mineralization events our study suggests that au and ag pb zn veins hosted in the same metamorphic terrains may not be genetically related to each other

on the relationship between climate and neandertal fire use during the last glacial in south west france abstract both environmental and cultural factors dictate how when and where hunter gatherers use fire in the landscape as well as how well evidence for any one fire will preserve in the archaeological record variability in the production and preservation of anthropogenic fire traces can potentially skew our perception of fire use in the past with this in mind the research presented in this article weighs in on the debate concerning neandertal fire use and fire making specifically the assertion that neandertals were unable to produce fire for themselves sandgathe et al 2011a 2011b this hypothesis is based on the inferred correlation between climatic deterioration concurrent lowering of lightning ignited fire frequencies and reduced signals for fire use in layers presumably deposited during the lower pleniglacial marine isotope stage 4 at the middle palaeolithic sites of roc de marsal and pech de l aze iv aquitaine basin southwestern france the logic being that if neandertals could produce fire at will fire use signals would remain largely consistent throughout the deposits despite there being limited access to natural fires in the landscape during this colder period this review challenges these assertions at multiple scales by looking at regional lightning and fire regime dynamics comparing the fire signals observed at roc de marsal and pech de l aze iv to those of other sites nearby and around france and exploring the various environmental and cultural factors likely influencing these signals ultimately the data suggests that estimated reductions in lightning frequencies and fire regime during the lower pleniglacial and colder stadial periods in general were not adequate to severely limit neandertal access to natural fire while possible artefactual evidence for neandertal fire making challenges the assumption that they were at all reliant on lightning ignited fire moreover at the nearby neandertal site of combe grenal the majority of the layers exhibiting evidence of fire use have cold climatic signals suggesting the fire use trends observed at roc de marsal and pech de l aze iv are potentially local expressions of changes in regional site use patterns possibly brought on by increased reliance on highly mobile migratory reindeer prey species and reductions in local woodfuel availability during cold periods other factors potentially reducing the archaeological visibility of cold climate fire use are discussed

the possibility of a zns bearing sulfide melt at 600 c evidence from the rajpura dariba deposit india supported by laboratory melting experiment abstract inclusions of euhedral pyrite crystals are seen within sphalerite occupying veins and fractures in the rajpura dariba zn pb cu sulfide deposit in rajasthan india sphalerite in the deposit shows wide variation in composition and contains high sulfur with fe s zn varying from 0 49 to 1 06 indicating that a portion of the fe in sphalerite could be expressed as a pyrite fes 2 component and that the pyrite inclusions within sphalerite in the vein ore could have formed due to exsolution we have conducted experiments by the evacuated silica tube method at 600 c pertinent to the peak metamorphic conditions of the rajpura dariba deposit our experiments were aimed at exploring the possibility of a zns bearing sulfide partial melt that could precipitate sufficiently s rich sphalerite which in turn might exsolve pyrite the starting mixture comprised synthetic fes zns pbs cu 2 s and s in the molar proportions of 40 33 9 9 and 9 respectively which approximately corresponded to molar proportions of 27 fes 40 zns 11 pbs and 22 cufes 2 electron probe micro analysis epma of the resulting run product showed the presence of a cu fe zn pb s melt containing 4 61 mol zns in the coexisting sphalerite the estimated fes 2 component was 9 07 mol the eutectic temperature was determined to be 595 c with a melt containing 22 44 mol fes 31 24 mol cu 2 s 5 37 mol zns 35 81 mol pbs and 5 14 mol fes 2 the sphalerite that was in equilibrium with the eutectic melt contained 6 72 mol fes 2 our experimental results suggest that a zns bearing sulfide melt containing as high as 5 mol zns was produced during metamorphism at rajpura dariba by partial melting of the preexisting ore further experiments confirmed that a minimum sulfur fugacity of 2 46 log units is required for initiating melting pyrite and sphalerite containing fe and stoichiometrically excess s are the solidus phases present in all melt bearing experimental run products except one with much higher zns suggesting that these two minerals at rajpura dariba could have simultaneously crystallized from a sulfide partial melt giving rise to the observed poikilitic textural relation between the two

gold remobilisation and formation of high grade ore shoots driven by dissolution reprecipitation replacement and ni substitution into auriferous arsenopyrite abstract both gold rich sulphides and ultra high grade native gold oreshoots are common but poorly understood phenomenon in orogenic type mineral systems partly because fluids in these systems are considered to have relatively low gold solubilities and are unlikely to generate high gold concentrations the world class obuasi gold deposit ghana has gold rich arsenopyrite spatially associated with quartz veins which have extremely high localised concentrations of native gold contained in microcrack networks within the quartz veins where they are folded here we examine selected samples from obuasi using a novel combination of quantitative electron backscatter diffraction analysis ion microprobe imaging synchrotron xfm mapping and geochemical modelling to investigate the origin of the unusually high gold concentrations the auriferous arsenopyrites are shown to have undergone partial replacement 15 by au poor nickeliferous arsenopyrite during localised crystal plastic deformation intragranular microfracture and metamorphism 340 460 c 2 kbars our results show the dominant replacement mechanism was pseudomorphic dissolution reprecipitation driven by small volumes of an infiltrating fluid that had relatively low s 2 and carried aqueous nicl 2 we find that arsenopyrite replacement produced strong chemical gradients at crystal fluid interfaces due to an increase in s 2 during reaction which enabled efficient removal of gold to the fluid phase and development of anomalously gold rich fluid potentially 10 ppm or more depending on sulphur concentration this process was facilitated by precipitation of ankerite which removed co 2 from the fluid increasing the relative proportion of sulphur for gold complexation and inhibited additional quartz precipitation gold re precipitation occurred over distances of 10 m to several tens of metres and was likely a result of sulphur activity reduction through precipitation of pyrite and other sulphides we suggest this late remobilisation process may be relatively common in orogenic belts containing abundant mafic ultramafic rocks which act as a source of ni and co scavenged by chloride bearing fluids both the preference of the arsenopyrite crystal structure for ni and co rather than gold and the release of sulphur during reaction can drive gold remobilisation in many deposits across broad regions

estimation of arctic glacier motion with satellite l band sar data offset fields between pairs of jers 1 satellite sar data acquired in winter with 44 days time interval were employed for the estimation of arctic glacier motion over svalbard novaya zemlya and franz josef land the displacement maps show that the ice caps are divided into a number of clearly defined fast flowing units with displacement larger than about 6 m in 44 days i e 50 m year the estimated error of the jers 1 offset tracking derived displacement is on the order of 20 m year occasionally azimuth streaks related to auroral zone ionospheric disturbances were detected and dedicated processing steps were applied to minimize their influence on the estimated motion pattern our analysis demonstrated that offset tracking of l band sar images is a robust and direct estimation technique of glacier motion the method is particularly useful when differential sar interferometry is limited by loss of coherence i e for rapid and incoherent flow and large acquisition time intervals between the two sar images the jers 1 results obtained using sar data acquired by a satellite operated until 1998 raise expectations of l band sar data from the alos satellite launched in early 2006

observations of ice sheet motion in greenland using satellite radar interferometry we present interferometric observations of ice sheet motion in western greenland based on pairs of ers 1 synthetic aperture radar sar images these observations provide the first detailed regional view of ice motion associated with dynamically supported topography near the margin of an ice sheet the interferograms of this area are much more complicated than other interferograms of ice sheets presented to date we devote the largest part of this paper to explaining the source of the complexity in these interferograms a synthetic interferogram based on a simple model helps to illustrate the effects of different components of the ice velocity field in interferometric data and suggests a method for estimating the large scale ice velocity field from such data

textural evidence for extensive melting of the broken hill orebody galena pyrrhotite and chalcopyrite in samples of zn rich ore from the broken hill orebody show textures similar to those in partially melted metamorphic rocks including strings of low melting phases separating lithons of minerals likely to be restite low dihedral angles between low melting temperature minerals and restitic minerals and enlargement of these dihedral angles due to partial annealing analysis of existing experimental work from the system fe pb zn s indicates that at 1 bar galena and sphalerite coexisting with pyrrhotite of the compositions found at broken hill would have been partially melted at temperatures of about 750 c at 5 kbars this melting would occur at 780 c this temperature is well within the range of metamorphic temperatures reported from the area from these data we conclude that the broken hill orebody was partially molten at peak metamorphism with much of the pb cu ag sb and as in the melt and fe and zn residing mostly in the restite differentiation during cooling enriched the residual melt in sb as ag and other low melting temperature chalcophile elements the main sulfide melt froze after the last penetrative deformation to affect the orebody at temperatures below 720 c and possibly as low as 650 c sulfosalts crystallized out of the remaining melt at temperatures of 600 to 450 c and the final melt crystallized native bismuth at ca 250 c

satellite image derived velocity field of an antarctic ice stream the surface velocity of a rapidly moving ice stream has been determined to high accuracy and spatial density with the use of sequential satellite imagery variations of ice velocity are spatially related to surface undulations and transverse velocity variations of up to 30 percent occur such large variations negate the concept of plug flow and call into question earlier mass balance calculations for this and other ice streams where sparse velocity data were used the coregistration of images with the use of the topographic undulations of the ice stream and the measurement of feature displacement with cross correlation of image windows provide significant improvements in the use of satellite imagery for ice flow determination

230 th 234 u age of a mousterian site in france pech de l aze is a group of caves and rock shelters near sarlat in the dordogne district of south west france in the cave pech i there occurs a remanent of breccia containing mousterian middle palaeolithic artefacts of denticulate and typical varieties overlying a travertine layer we have used the 230th 234u dating method to determine the age of this travertine 123 15 kyr this age is consistent with deposition of this travertine during isotope state 5e the warmest substage of the last interglacial we show here that this result is consistent with geological and palaeontological estimates of the age of sediments filling the cave1

partial melting of the broken hill galena sphalerite ore experimental studies in the system pbs fes zns ag2s for many years the genesis of the broken hill pb zn ag deposit has been and continues to be hotly debated mostly because many of the original characteristics of the deposit have been obscured by high grade metamorphism and deformation metamorphism not only overprinted the deposit but fundamentally modified the sulfides through metamorphic remobilization based on experimental studies it had also been speculated that partial melting of the sulfides may have occurred the lack of experimental data at elevated pressures in the pbs fes zns system has limited this suggestion to mere speculation we present the results of an experimental study of the melting behavior of sulfides which show that broken hill ores must have been partially molten under peak metamorphic conditions

combination of srtm3 and repeat aster data for deriving alpine glacier flow velocities in the bhutan himalaya abstract the present study evaluates the fusion of dems from the advanced spaceborne thermal emission and reflection radiometer aster instrument and the shuttle radar topography mission srtm the study area consists of high elevation glaciers draining through the rough topography of the bhutan himalayas it turns out that the aster derived and srtm3 dems have similar accuracy over the study area but the srtm3 dem contains less gross errors however for rough topography large sections of the srtm3 dem contain no data we therefore compile a combined srtm3 aster dem from this final composite master dem we produce repeat aster orthoimages from which we evaluate the dem quality and derive glacier surface velocities through image matching the glacier tongues north of the himalayan main ridge which enter the tibet plateau show maximum surface velocities in the order of 100 200 m year 1 in contrast the ice within the glacier tongues south of the main ridge flows with a few tens of meters per year these findings have a number of implications among others for glacier dynamics glacier response to climate change glacier lake development or glacial erosion the study indicates that space based remote sensing can provide new insights into the magnitude of selected surface processes and feedback mechanisms that govern mountain geodynamics

recent antarctic ice mass loss from radar interferometry and regional climate modelling observed estimates of ice losses in antarctica combined with regional modelling of ice accumulation in the interior suggest that east antarctica is close to a balanced mass budget but large losses of ice occur in the narrow outlet channels of west antarctic glaciers and at the northern tip of the antarctic peninsula

on the initiation of metamorphic sulfide anatexis mineral assemblages in common sulfide ore deposits are examined together with phase relations to 1 investigate the pressure temperature conditions required for the onset of metamorphically induced partial melting involving economic minerals and 2 place constraints on the amount of melt produced deposits that contain sulfosalt or telluride minerals may start to melt at conditions ranging from lowest greenschist facies to amphibolite facies deposits lacking sulfosalt and or telluride minerals may begin to melt once p t conditions reach the upper amphibolite facies if galena is present or well into the granulite facies if galena is absent the result is two broad melting domains a lowto medium temperature low melt volume domain involving melting of volumetrically minor sulfosalt and or telluride minerals and a high temperature potentially higher melt volume domain involving partial melting of the major sulfide minerals epithermal gold deposits which are especially rich in sulfosalt minerals are predicted to commence melting at the lowest temperatures of all sulfide deposit types massive pb zn cu deposits may start to melt in the lower to middle amphibolite facies if pyrite and arsenopyrite coexist at these conditions and in the upper amphibolite facies if they do not excepting sulfosalt bearing occurrences massive ni cu pge platinum group element deposits will show little to no melting under common crustal metamorphic conditions whereas disseminated cu deposits are typically incapable of generating melt until the granulite facies is reached when partial melting commences in bornite bearing rocks the volume of polymetallic melt that can be generated in most deposit types is therefore largely a function of the abundance of sulfosalt minerals even at granulite facies conditions this volume is usually less than 0 5 the exception is massive pb zn deposits where melt volumes significantly exceeding 0 5 vol may be segregated into sulfide magma dykes allowing mobilization over large distances

the willyama supergroup in the broken hill and euriowie blocks new south wales abstract the willyama supergroup consists of highly deformed metasedimentary schists and gneisses with abundant quartzofeldspathic gneisses lesser basic gneisses and minor lode rocks prograde metamorphism ranged from andalusite through sillimanite to granulite grade radiometric dating in the broken hill block indicates separation of the source of the quartzo feldspathic gneisses from the mantle at 2300 2100 ma a rb sr model source age of 1820 60 ma has been interpreted as the maximum age of deposition deformation d 1 and or d 2 was coincident with high grade metamorphism at 1660 10 ma minor mundi mundi type granitoids and some pegmatites were intruded at 1490 20 ma minor pyroxenites at 561 7 ma dolerite dykes soon after and zoned pegmatites at 500 ma in association with the delamerian orogeny which reactivated retrograde schist zones at 520 40 ma subsequent history mostly comprises faulting weathering uplift and erosion the willyama supergroup has an estimated total thickness of 7 9 km with neither top nor basement exposed no unconformities have been recognized in the sequence the supergroup was deposited in a deepening environment passing upward from sandy facies to more shaly and fine sandy facies and from interpreted bimodal acid basic volcanics to non volcanic facies the metasediments have been interpreted as shelf sediments overlain by deeper water turbidites and minor contourites recently they have been reinterpreted as shallow marine with the quartzo feldspathic gneisses interpreted as fluvio deltaic arkoses in this paper the sequence to the top of thackaringa group is interpreted as mainly fluvio deltaic and lacustrine the broken hill group and sundown group are interpreted as shallow marine the paragon group may have comprised shelf muds overlain by delta front and lacustrine sediments in turn overlain by deeper water fine grained turbidites the broken hill orebody near the top of broken hill group consists of a series of stacked lenses much recent work has concluded that the deposit is volcanic exhalative in origin probably formed from seawater convected through the sequence and driven by heat from high level magma chambers however some features of the deposit are more appropriate to a sedimentary exhalative origin and models have been proposed involving seismic pumping of connate water with ore deposition on or below the seafloor devolatilization of the mantle has been proposed as a source of ore constituents deposition may have occurred in a narrow ne sw trending seafloor depression the willyama supergroup was probably deposited in a rift zone with thin crust the basic gneisses are interpreted as fe rich tholeiites similar to basalts from some oceanic spreading ridges the intense folding post folding leucogranitic intrusions and extensive granulite amphibolite facies metamorphism could have resulted from a collision following subduction however there is no direct evidence of oceanic crust or subduction and the low pressure metamorphic path does not suit a collision model the rocks were probably deposited in a continental rift with some similarities to those interpreted for proterozoic fold belts in northern australia

rapid and synchronous ice dynamic changes in east greenland two major outlet glaciers in east greenland have suddenly begun to accelerate and retreat the speeds of kangerdlugssuaq and helheim remained steady during the 1990s despite progressive and substantial thinning but have abruptly increased within the last two years more than doubling ice flux to the ocean had it been an isolated example the comparable 1998 speed up of jakobshavn isbra in west greenland might have been explained simply by its chance retreat past a pinning point now that two further greenland outlets have exhibited similar behavior a common process seems likely a remarkable correspondence in the inter annual patterns of speed and ice front variation between kangerdlugssuaq and helheim implies a significant sensitivity to regional environmental factors the period of continued warming and thinning appears to have primed these glaciers for a step change in dynamics not included in current models we should expect further greenland outlet glaciers to follow suit copyright 2006 by the american geophysical union

a multi method luminescence dating of the palaeolithic sequence of la ferrassie based on new excavations adjacent to the la ferrassie 1 and 2 skeletons abstract a new interdisciplinary project was initiated to excavate a portion of the palaeolithic site of la ferrassie left intact by earlier excavations one of the aims of this project was to provide chronological information on the succession of middle and upper palaeolithic layers as well as on the skeletons unearthed by capitan and peyrony in the early 1900 s we report here preliminary results on the lithics faunal remains site formation processes and on the stratigraphic context of the la ferrassie 1 and 2 skeletons that were found adjacent to our excavations finally results from luminescence dating of the sediments and a preliminary set of radiocarbon ages are presented quartz osl both at the multi grain and single grain levels of analysis and post ir irsl of feldspar at various stimulation temperatures are compared the quartz feldspar comparison revealed a bleaching problem for the quartz osl and the feldspar pirir signals from layer 2 as a consequence the age of this layer was determined using a minimum age model a mousterian industry with bifaces at the base of the sequence has been dated between 91 9 and 44 3 ka the ferrassie mousterian layers are attributed to mis 3 between 54 3 and 40 2 ka and thus appear very late in the final middle palaeolithic of the region furthermore these ages constrain the chronology of the la ferrassie 1 and 2 skeletons which have been attributed to one of these ferrassie mousterian layers the ch telperronian layer is dated to 42 3 ka and the aurignacian to 37 2 ka implications of the ages for the la ferrassie 1 and 2 skeletons and for the variability of late mousterian are discussed

seasonal speedup along the western flank of the greenland ice sheet it has been widely hypothesized that a warmer climate in greenland would increase the volume of lubricating surface meltwater reaching the ice bedrock interface accelerating ice flow and increasing mass loss we have assembled a data set that provides a synoptic scale view spanning ice sheet to outlet glacier flow with which to evaluate this hypothesis on the ice sheet these data reveal summer speedups 50 to 100 consistent with but somewhat larger than earlier observations the relative speedup of outlet glaciers however is far smaller 15 furthermore the dominant seasonal influence on jakobshavn isbrae s flow is the calving front s annual advance and retreat with other effects producing outlet glacier speedups an order of magnitude larger seasonal melt s influence on ice flow is likely confined to those regions dominated by ice sheet flow

greenland ice sheet surface properties and ice dynamics from ers 1 sar imagery c band synthetic aperture radar sar imagery from the european space agency s ers 1 satellite reveals the basic zonation of the surface of the greenland ice sheet the zones have backscatter signatures related to the structure of the snowpack which varies with the balance of accumulation and melt at various elevations the boundaries of zones can be accurately located with the use of this high resolution imagery the images also reveal a large flow feature in northeast greenland that is similar to ice streams in antarctica and may play a major role in the discharge of ice from the ice sheet

chronology of the middle palaeolithic open air site of combe brune 2 dordogne france a multi luminescence dating approach abstract the bergerac region of south western france is well known for its wealth of middle palaeolithic open air sites however their chronology remains poorly understood due to the complexity of the deposits and difficulties applying radiometric dating techniques combe brune 2 excavated in 2006 and 2007 by the inrap institut national de recherches archeologiques preventives comprises a substantial stratigraphic sequence providing an almost continuous sedimentary record that is unique for the region three lithic assemblages were documented in the eastern part of the site and six stratified assemblages in the western part five of which are concentrated in unit 7 all the clearly individualised industries portray an unequivocal techno economic coherence and are dominated by levallois debitage minerals present in the sediments were dated by the optically stimulated luminescence osl using different protocols thermal transfer tt osl for quartz grains and irsl and post ir irsl for feldspar grains heated flints were also dated by thermoluminescence tl dating results obtained from quartz and feldspars grains provide an age of 234 25 ka for unit 8 at the base of the western sequence 161 18 to 97 3 12 ka for unit 7 63 1 6 5 ka for unit 4 and a series of ages ranging from 39 2 4 0 to 22 3 2 2 ka for unit 3 tl ages obtained from heated flints recovered from the base of unit 7 in the eastern section range from 183 20 to 195 16 ka these results are in good agreement and are stratigraphically coherent suggesting that the early middle palaeolithic occupation the first documented for the bergerac region can be placed at the end of marine isotopic stage mis 7 and the beginning of mis 6

evidence of sulfide melting and melt fractionation during amphibolite facies metamorphism of the rajpura dariba polymetallic sulfide ores abstract partial melting of sulfide ores during prograde metamorphism could have been more prevalent than generally accepted however identification of such melting is difficult as sulfide melts do not form glasses and the textures generated on quenching are obliterated due to the tendency of sulfides for ready recrystallization the polymetallic base metal sulfide deposit at rajpura dariba rajasthan india is a typical stratiform ore metamorphosed to the middle amphibolite facies the peak metamorphic temperature of 600 c should have been sufficient to initiate sulfide melting as evident from experimental studies in the zns pbs cu 2 s fes 2 s system further syn metamorphic melting of the original sedex ore was abetted by the high f s2 condition that prevailed as a consequence of barite dissolution a zn fe s melt containing minor pb sb and cu but no ag fractionated from an initial melt in the above system resulting in a residual immiscible sulfosalt bearing pbs melt the final metallic melts represented by formation of dyscrasite ag 3 sb from the sulfosalt bearing melt and breithauptite nisb or ullmannite nisbs from the sulfosalt absent melt were a product of independent fractional crystallization of the immiscible sulfide and pbs sulfosalt melts

ice velocity determined using conventional and multiple aperture insar abstract we combine conventional interferometric synthetic aperture radar insar and multiple aperture insar mai to determine the ice surface velocity on the langjokull and hofsjokull ice caps in iceland in 1994 this approach allows the velocity of the 20 principal ice cap outlet glaciers to be fully resolved we show that mai leads to displacement estimates of finer resolution 15 versus 150 m and superior precision 5 versus 15 cm to those afforded by the alternative technique of speckle tracking using sar data acquired in ascending and descending orbits we show that ice flows within 15 of the direction of maximum surface slope across 66 of the ice caps it is therefore possible to determine ice displacement over the majority of the ice caps using a single sar image pair thereby reducing errors associated with temporal fluctuations in ice flow

surface motion of mountain glaciers derived from satellite optical imagery a complete and detailed map of the ice velocity field on mountain glaciers is obtained by cross correlating spot5 optical images this approach offers an alternative to sar interferometry because no present or planned radar satellite mission provides data with a temporal separation short enough to derive the displacements of glaciers the methodology presented in this study does not require ground control points gcps the key step is a precise relative orientation of the two images obtained by adjusting the stereo model of one slave image assuming that the other master image is well georeferenced it is performed with numerous precisely located homologous points extracted automatically the strong ablation occurring during summer time on the glaciers requires a correction to obtain unbiased displacements the accuracy of our measurement is assessed based on a comparison with nearly simultaneous differential gps surveys performed on two glaciers of the mont blanc area alps if the images have similar incidence angles and correlate well the accuracy is on the order of 0 5 m or 1 5 of the pixel size similar results are also obtained without gcps an acceleration event observed in early august for the mer de glace glacier is interpreted in term of an increase in basal sliding our methodology applied to spot5 images can potentially be used to derive the displacements of the earth s surface caused by landslides earthquakes and volcanoes

a multistage genetic model for the metamorphosed mesoproterozoic swartberg base metal deposit aggeneys gamsberg ore district south africa

perito moreno glacier argentina flow estimation by cosmo skymed sequence of high resolution sar x imagery abstract the perito moreno glacier los glaciares national park patagonia argentina ice stream has been investigated using x band sar amplitude images collected from february to december 2009 excluding june at time intervals of 8 and 16 days by the cosmo skymed satellites the high spatial resolution dataset 10 10 km swath 1 m per pixel reveals many details of the glacier surface and the ice velocity fields extracted from sequential image pairs by the maximum cross correlation method cover most of the glacier area the efficiency of the cross correlation method improves with high spatial resolution imagery and the co registration error of the image pair also reduces the glacier motion detected in the period shows variability on the time scale considered evidencing the areas of higher dynamics under different speed regimes

changes in the velocity structure of the greenland ice sheet using satellite radar interferometry observations of greenland we detected widespread glacier acceleration below 66 north between 1996 and 2000 which rapidly expanded to 70 north in 2005 accelerated ice discharge in the west and particularly in the east doubled the ice sheet mass deficit in the last decade from 90 to 220 cubic kilometers per year as more glaciers accelerate farther north the contribution of greenland to sea level rise will continue to increase

sulfide melts in ore deposits from low grade metamorphic settings insights from fluid and tl rich sulfosalt microinclusions from the monte arsiccio mine apuan alps tuscany italy abstract sulfide melting is increasingly recognized as an efficient ore remobilization process in several ore bodies deformed and metamorphosed under amphibolite to granulite facies conditions actually sulfide melts may also occur at lower metamorphic conditions provided the abundance of the so called low melting point chalcophile elements lmce the monte arsiccio ore body apuan alps northern tuscany italy is strongly enriched in several lmce i e ag as hg pb sb and tl and experienced greenschist facies metamorphism t 350 450 c p 0 3 0 4 gpa during the alpine orogeny trails of polyphase sulfosalt inclusions up to five phases coexisting with fluid inclusions were observed within quartz and baryte crystals found in late stage veins sulfosalt assemblages are formed by lmce rich phases the main being ferdowsiite ag8as3sb5s16 chabourneite tl2pb sb as 10s17 and intermediate members of the arsiccioite routhierite isotypic pair ag1 xcux hg2tlas2s6 along with minor realgar sulfosalt inclusions range between 200 nm and more than 100 m in size whereas larger inclusions likely formed through the coalescence of smaller melt droplets are up to 500 m sulfosalt inclusions are associated with primary two phase liquid rich fluid inclusions type 1a containing co2 and n2 as revealed by microthermometric investigations and micro raman spectroscopy secondary two phase liquid rich fluid inclusions type 1b were also identified microthermometric measurements carried out on type 1a fluid inclusions gave homogenization temperatures th in the range 265 296 c whereas type 1b fluid inclusions showed lower th between 222 and 246 c as microthermometric heating experiments on sulfosalt inclusions revealed homogenization temperatures around 270 c it is very likely that sulfosalt inclusions were in the liquid state during their entrapment in agreement with many tl bearing systems these results are fully consistent with the occurrence of lmce rich sulfide melt during the formation of the sulfosalt assemblages observed at the monte arsiccio mine in addition the polyphase nature of most of the observed sulfosalt inclusions may be related to the unquenchable nature of sulfide melts the formation of lmce rich sulfosalt assemblages could be related to the release of these elements from pyrite during its metamorphic recrystallization consequently pyrite ores may produce sulfide melts with potential implications in the change of speciation of lmce from trace to major elements

analyzing yengisogat glacier surface velocities with alos palsar data feature tracking karakoram china little is known about the detailed behavior of glaciers in the karakoram mountains advanced land observing satellite alos phased array type l band synthetic aperture radar palsar data were used to obtain the surface velocity of the yengisogat glacier in the karakoram mountains four alos palsar data sets with 46 days temporal baseline acquired from 2007 to 2009 covered all four seasons and were used to extract the offset fields and estimate annual average surface velocity based on seasonal velocities for the alos palsar data the synthetic aperture radar sar feature tracking procedures within the gamma software were utilized instead of sar interferometry because of low coherence in case of fast moving glaciers or large time intervals between the image acquisitions the accuracy of the measurements is discussed and the measurements were consistent with previous results from optical imagery feature tracking it was revealed that the south tributaries contributed to the main flow of the glacier with the glacier surface velocities of the south tributaries moving more rapidly than the north tributaries this was mainly attributed to the effect of the glacier s aspect in the glacier long term development point of view seasonal and spatial variations of the glacier surface velocity imply that the tributary south skamri glacier is probably surging this has previously been mentioned by some researchers such as copland et al the equilibrium line altitude was found to be at about 5 000 m a s l for south tributaries estimated from the surface velocity distribution along the glacier centerline

velocity structure flow instability and mass flux on a large arctic ice cap from satellite radar interferometry satellite radar interferometry allows calculation of the ice surface velocity distribution throughout the largest ice cap in the eurasian arctic austfonna in eastern svalbard data on ice cap velocity structure show strong spatial variations observed in unprecedented detail ice cap drainage basins have clearly defined fast flowing units with marked shear margins at the surface associated with troughs in the subglacial bedrock identified from 60 mhz ice penetrating radar interferometric measurements show that the velocity structure in most ice cap drainage basins remained stable over a 2 year period unexpectedly however in the basin where surface velocities were the highest on the ice cap at 140 m yr 1 in winter 1992 the flow rate had halved by winter 1994 a time series of visible band landsat imagery shows that this basin was relatively inactive between 1973 and 1991 but had a distinctly disturbed surface in 1993 this flow instability was initiated after summer 1991 and is likely to be a glacier surge or mini surge demonstrating the increasing diversity of motion events revealed by radar interferometry mass flux through this basin calculated using ice velocity and thickness data was 0 1 km 3 yr 1 in 1992 an increase of up to two orders of magnitude over that prior to flow instability calculated balance velocity is an order of magnitude less than the interferometrically derived velocity implying that the flow rates observed for the fast flowing unit cannot be sustained under the present climate c 1999 elsevier science b v all rights reserved

glacier retreat as a result of climate warming and increased precipitation in the tarim river basin northwest china the tarim river basin a river system formed by the convergence of nine tributaries is the most heavily glacierized watershed in arid northwest china in the basin there are 11 665 glaciers with a total area of 19 878 km 2 and a volume of 2313 km 3 glaciers in the basin play a significant role in the water resource system it is estimated that they provide about 133 10 8 m 3 of meltwater annually contributing 39 of the total river runoff under the influence of global warming northwest china has experienced a generally warmer and drier climate since the mid 19th century however a so called warm and wet transition has occurred since the late 1980s evidenced by an increase in both precipitation and stream discharge in the xinjiang autonomous region and neighboring regions this paper describes how glaciers in the tarim river basin have responded to such warming and increased precipitation and the impact of these glacier changes we analyzed the variations of more than 3000 glaciers since the 1960s using topographical maps high resolution satellite images and aerial photographs of the river basin our results indicate that glaciers in the basin have been mostly in retreat in the past 40 years and ice wastage has significantly influenced water resources in the tarim river basin estimation by a degree day meltwater model shows the positive anomaly in stream runoff of the tailan river can be partly attributed to the increase in glacier runoff amounting to one third of the stream discharge and a rough estimation using observed average ablation on the termini of 15 glaciers in china verifies that the mass loss calculated by a glacier area volume relation is reasonable 1 study area

thermoluminescence dates for the middle palaeolithic site of chez pinaud jonzac france thermoluminescence dating of heated flint artefacts from the middle palaeolithic sequence of chez pinaud jonzac france places an assemblage of quina type mousterian into mis 4 while the overlying assemblage of denticulate mousterian which is followed by two layers with mousterian of acheulean tradition are all assigned to mis 3 tl dating is used to verify the mixed nature of deposits from which diagnostic middle as well as upper palaeolithic tools were recovered the tl ages are significantly different for samples from this layer and broadly agree with the archaeological attributions while the study is generally limited by the low number of heated samples available a correlation with a generalized chronostratigraphic sequence is possible by including proxy data from the faunal remains associated with the lithic assemblages in question the quina mousterian in southwestern france therefore can be placed by chronometric dating methods in mis 4 to mis 3

ice flow of the antarctic ice sheet we present a reference comprehensive high resolution digital mosaic of ice motion in antarctica assembled from multiple satellite interferometric synthetic aperture radar data acquired during the international polar year 2007 to 2009 the data reveal widespread patterned enhanced flow with tributary glaciers reaching hundreds to thousands of kilometers inland over the entire continent this view of ice sheet motion emphasizes the importance of basal slip dominated tributary flow over deformation dominated ice sheet flow redefines our understanding of ice sheet dynamics and has far reaching implications for the reconstruction and prediction of ice sheet evolution

the contribution of lithic production systems to the interpretation of mousterian industrial variability in south western france the example of combe grenal dordogne france disentangling the relative contribution of the various factors underlying middle palaeolithic industrial variability remains one of the foremost problems for researchers interested in neandertal technological and behavioural adaptations the site of combe grenal dordogne has figured prominently in these discussions given its long stratigraphic sequence and rich archaeological record that extends from mis 6 to mis 3 and contains all of f bordes mousterian facies departing from a strict typological approach we provide a revised vision of the site s sequence focused on individualising lithic production systems we investigate to what extent typologically different industries beyond their separation imposed by the very idea of discrete mousterian facies nevertheless portray comparable production systems by eschewing a chronology of the traditional mousterian facies our technological approach to the combe grenal assemblages succeeded in identifying a clear stratigraphic succession where strictly typological approaches had previously failed moreover comparison with other regional sequences shows the succession of mousterian technological systems identified at combe grenal not to be an exception in south western france we propose a revised chronology for the site s sequence based on a correlation of changes in the structure of regional faunal communities with independent palaeo environmental data finally comparing technological data with raw material provisioning strategies and elements of faunal exploitation such as prey availability provides insights concerning the interpretation of mousterian variability and the investigation of changing patterns of neandertal landscape use

middle to upper palaeolithic site formation processes at the bordes fitte rockshelter central france transformation in technological patterns associated with the middle to upper palaeolithic transition between 50 and 40 ka in western europe and their relationship with the neanderthal and anatomically modern human populations and behaviors are issues that continue to stimulate heated debate in this article we use the middle and early upper palaeolithic archaeo stratigraphic record from the bordes fitte rockshelter les roches d abilly site central france a bayesian analysis of the ages obtained by accelerator mass spectrometry radiocarbon on ultrafiltered collagen and by luminescence on quartz and feldspar grains to establish a timeline for material culture and sedimentary dynamic changes during the middle to upper palaeolithic transition technology refitting studies and taphonomy of lithic artifacts recovered in the geoarchaeological field units d1 and d2 permit to characterize 3 reduction strategies levallois discoidal and ch telperronian blade that took place between the cold heinrich events 5 and 4 we discuss the implications of the results to characterize the end of the middle palaeolithic and for distinguishing anthropogenic and non anthropogenic factors in middle to upper palaeolithic assemblage s variability

water activity changes across an amphibolite granulite facies transition broken hill australia phase compositions in pelitic and mafic gneisses place tight constraints on pressure ranging from 3 up to 6 kb and to a lesser extent on temperature 500 up to 800 c during prograde regional metamorphism of the willyama complex broken hill se australia these limits allow an evaluation of water activity across the terrain using various equilibria in pelitic and mafic gneisses the stability of cummingtonite and biotite over much of the terrain places upper limits on temperature and the presence of syn metamorphic partial melts in the metasediments places lower limits on a h2o garnet biotitesillimanite k feldspar quartz relations combined with the partial melting data suggest a decrease in water activity from near 1 0 in the lower grade zones to 0 5 0 2 in the broken hill little broken hill part of the two pyroxene zone this result is compatible with less precise hornblende orthopyroxene clinopyroxene quartz relations

rapid disintegration of alpine glaciers observed with satellite data analyses of multispectral satellite data indicate accelerated glacier decline around the globe since the 1980s by using digitized glacier outlines inferred from the 1973 inventory and landsat thematic mapper tm satellite data from 1985 to 1999 we obtained area changes of about 930 alpine glaciers the 18 area reduction as observed for the period 1985 to 1999 1 3 a corresponds to a seven times higher loss rate compared to the 1850 1973 decadal mean extrapolation of area change rates and cumulative mass balances to all alpine glaciers yields a corresponding volume loss of about 25 km since 1973 highly individual and non uniform changes in glacier geometry disintegration indicate a massive down wasting rather than a dynamic response to a changed climate our results imply stronger ongoing glacier retreat than assumed so far and a probable further enhancement of glacier disintegration by positive feedbacks

extracting a climate signal from 169 glacier records i constructed a temperature history for different parts of the world from 169 glacier length records using a first order theory of glacier dynamics i related changes in glacier length to changes in temperature the derived temperature histories are fully independent of proxy and instrumental data used in earlier reconstructions moderate global warming started in the middle of the 19th century the reconstructed warming in the first half of the 20th century is 0 5 kelvin this warming was notably coherent over the globe the warming signals from glaciers at low and high elevations appear to be very similar

mass balance of glaciers and ice caps consensus estimates for 1961 2004 1 working with comprehensive collections of directly measured data on the annual mass balance of glaciers other than the two ice sheets we combine independent analyses to show that there is broad agreement on the evolution of global mass balance since 1960 mass balance was slightly below zero around 1970 and has been growing more negative since then excluding peripheral ice bodies in greenland and antarctica global average specific balance for 1961 1990 was 219 112 kg m 2 a 1 representing 0 33 0 17 mm sle sea level equivalent a 1 for 2001 2004 the figures are 510 101 kg m 2 a 1 and 0 77 0 15 mm sle a 1 including the smaller greenland and antarctic glaciers global total balance becomes 0 38 0 19 mm sle a 1 for 1961 1990 and 0 98 0 19 mm sle a 1 for 2001 2004 for 1991 2004 the glacier contribution 0 77 0 26 mm sle a 1 is 20 30 of a recent estimate of 3 2 0 4 mm a 1 of total sea level rise for 1993 2005 while our error estimates are not rigorous we believe them to be liberal as far as they go but we also discuss several unquantified biases of which any may prove to be significant

glacier velocity measurements in the eastern yigong zangbo basin tibet china we apply the feature tracking method to l band synthetic aperture radar sar images to derive detailed motion patterns of glaciers in the yigong zangbo basin during summer 2007 the results indicate that the flow patterns are generally constrained by the valley geometry and terrain complexity the mean velocities of the 12 glaciers were 15 206 m a 1 with a maximum of 423 m a 1 for glacier no 5a the majority of the glaciers exhibited high and low velocities in their upper and lower sections respectively the glacier area ranges from 3 to 42 km 2 it is found that velocity shows a positive correlation with the glacier area and length many small scale temporal spatial variations in the glacier flow patterns were observed along the central glacier flowline

optical dating in archaeology thirty years in retrospect and grand challenges for the future in 1982 when richard klein first became one of the editors of this journal the luminescence dating community was embarking on a new phase of exploratory research attention was turning from the use of thermoluminescence tl dating to estimate the time of last heating of archaeological objects such as pottery and burnt flint to the tl dating of unheated sediments that had been transported by wind and then deposited on the landscape this revolutionary development enabled the extension of tl dating to sedimentary deposits in a variety of environmental settings and to the multitude of archaeological sites that lack suitably heated artefacts in sediment dating the age of most interest is usually the time elapsed since grains of quartz or feldspar were last exposed to sunlight as the energy of the sun s rays is sufficient to evict electrons from their light sensitive traps these traps are steadily refilled after sediment deposition and the longer the grains remain buried the more tl they will emit when measured in 1985 huntley and colleagues proposed optical dating as a simpler and superior means of stimulating the light sensitive traps in quaternary sediments and this is now the principal luminescence based method of dating geological and archaeological deposits optical dating is an umbrella term for an armada of acronyms the most common in archaeological contexts being osl optically stimulated luminescence tt osl thermally transferred osl irsl infrared stimulated luminescence and pirir post infrared irsl all of these variants are founded on the same basic tenet measurement of a light sensitive signal to determine typically the last time that sediment grains were sun bleached but each approach has its virtues and vices in this paper we review this family of luminescence dating techniques and look back on 30 years of optical dating in archaeology some of the more interesting and important achievements are highlighted including the critical insights gained in the last two decades from osl measurements of individual grains of quartz we also look to the future of optical dating in archaeological contexts efforts to extend the age limits of optical dating to older hominin and archaeological sites will remain a key goal and understanding how archaeological sites of all ages form and evolve over time could be improved greatly by combining micromorphology analysis with optical dating of undisturbed intact sediments the latter poses a series of particularly formidable technical challenges but if the past is any guide to the future then we can expect optical dating to illuminate much more of human history before celebrating its golden jubilee

glacier motion estimation using sar offset tracking procedures two image to image patch offset techniques for estimating feature motion between satellite synthetic aperture radar sar images are discussed intensity tracking based on patch intensity cross correlation optimization and coherence tracking based on patch coherence optimization are used to estimate the movement of glacier surfaces between two sar images in both slant range and azimuth direction the accuracy and application range of the two methods are examined in the case of the surge of monacobreen in northern svalbard between 1992 and 1996 offset tracking procedures of sar images are an alternative to differential sar interferometry for the estimation of glacier motion when differential sar interferometry is limited by loss of coherence i e in the case of rapid and incoherent flow and of large acquisition time intervals between the two sar images in addition an offset tracking procedure in the azimuth direction may be combined with differential sar interferometry in the slant range direction in order to retrieve a two dimensional displacement map when sar data of only one orbit configuration are available

felsic metavolcanic rocks related to the broken hill pb zn ag orebody australia geology depositional age and timing of high grade metamorphism two key issues related to the origin of the massive broken hill pb zn ag orebody are the genesis of its host rocks and their depositional age these granulite facies layered gneisses have been ascribed alternately to volcanic and nonvolcanic regimes determination of the depositional age of the sequence has never been seriously addressed north of broken hill amphibolite facies precursors to the granulite facies gneisses show compelling evidence of a volcanic origin in their texture chemistry and zircon morphology these felsic metavolcanic rocks are in the upper part of the broken hill group stratigraphically equivalent to the broken hill orebody the present work traces textural zircon morphological and isotopic changes across the amphibolite to granulite facies transition in order to determine the primary depositional age of this supracrustal sequence and the timing of highgrade regional metamorphism ion microprobe shrimp u pb data on zircons from the lower grade amphibolite facies felsic metavolcanic rocks define a major magmatic population at 1690 or 5 ma this is considered to be the age of zircon crystallization and eruption of felsic volcanics in this part of the broken hill group these shrimp data clarify inheritance and discordance problems that had plagued conventional multigrain u pb analyses zircon results from granulite facies stratigraphic equivalents of these rocks near southern cross and at broken hill have patterns similar to those of the amphibolite facies rocks including igneous relics that provide the same primary age additionally zircon in the highest grade granulite facies rocks approximately 800 degrees c forms metamorphic overgrowths surrounding the magmatic relics these younger zircon selvedges have a pooled age of 1600 or 8 ma which determines the timing of this granulite facies event consistent u pb monazite results yield this same age 1599 or 9 ma suggesting that the monazite blocking temperature is close to that of zircon or that cooling to 725 degrees c was achieved relatively rapidly this is some 60 m y younger than the previously accepted age for high grade metamorphism at broken hill irrespective of metamorphic grade in the gneisses all biotite rb sr ages have been reset to approximately 480 ma a reflection of early paleozoic delamerian orogenesis inherited zircon grains interpreted as xenocrysts and in some cases mantied by 1690 ma igneous rims have older proterozoic to late archcan ages 1780 2700 ma the presence of xenocrystic zircon components points to an ensialic tectonic setting for the broken hill block and reflects accidental incorporation in the felsic volcanic protoliths of lithic fragments and or complex igneous sources such as found in crust exposed in the gawler craton to the west the 1690 or 5 ma depositional age determined here provides a firm chronologic tie between the early proterozoic sequences enclosing major stratiform pb zn ag orebodies at broken hill mount isa 1670 or 19 ma and mcarthur river 1690 or 27 ma in northern australia in light of the uncertainties over timing and mode of origin of these deposits the similar ages of their host sequences have important implications for early proterozoic tectonics and metallogeny

combining satellite multispectral image data and a digital elevation model for mapping debris covered glaciers automated glacier mapping from satellite multispectral image data is hampered by debris cover on glacier surfaces supraglacial debris exhibits the same spectral properties as lateral and terminal moraines fluvioglacial deposits and bedrock outside the glacier margin and is thus not detectable by means of multispectral classification alone based on the observation of low slope angles for debris covered glacier tongues we developed a multisource method for mapping supraglacial debris the method combines the advantages of automated multispectral classification for clean glacier ice and vegetation with slope information derived from a digital elevation model dem neighbourhood analysis and change detection is applied for further improvement of the resulting glacier debris map a significant percentage of the processing can be done automatically in order to test the sensitivity of our method against different dem qualities it was also applied to a dem obtained from aster stereo data additionally we compared our multisource approach to an artificial neural network ann classification of debris using only multispectral data while the combination with an aster derived dem revealed promising results the ann classification without dem data does not

the potential of satellite radar interferometry and feature tracking for monitoring flow rates of himalayan glaciers abstract the stagnation of himalayan glaciers will only be exacerbated by a warming climate increasing hazards associated with glacier lake development frontal recession is a poor indicator of negative balance in this region where most glaciers are debris covered but reduced glacier flow rates provide a valuable warning of stagnation in situ measurements of velocity are understandably rare and remote sensing measurements have hitherto been limited by severe topography and lack of suitable data in this paper we compare two techniques to measure flow rates in everest region glaciers firstly satellite radar interferometry sri has recently become more viable because of improved digital elevation data and precision orbit models which now allow snapshots of velocities to be retrieved from ers imagery in the mid 1990s without ground control information secondly feature tracking between synthetic aperture radar sar images is found to be successful even on the small glaciers of this region because of the patterning associated with debris cover this technique extends through the 1990s and beyond the time frame over which velocities can be measured using the examples of the khumbu glacier flowing south into nepal and the kangshung glacier flowing east into china from the everest massif we compare sri and sar feature tracking in ers images consider the errors in these techniques and examine the potential to monitor flow rates across the region the techniques are found to be highly complementary and appropriate for monitoring flow rates in this region suggesting that routine monitoring of himalayan glaciers is possible the kangshung glacier appears to sustain relatively high flow rates of up to 10 cm day which along with a convex topographic profile indicates a healthy glacier not exhibiting significant negative mass balance in comparison much of the khumbu glacier appears to have stagnated the surface velocity at gorak shep is only 20 of a field based measurement in the 1970 s and the concave surface profile confirms the downwasting associated with a debris covered glacier in recession

glacier surface motion pattern in the eastern part of west kunlun shan estimation using pixel tracking with palsar imagery mountain glacier is considered as one of the most sensitive natural indicators of climate change glacier surface motion distribution in west kunlun shan wks has been attracting considerable attention and represents a fundamental glacier parameter for better understanding glacier dynamics ice mass balance and even for the climate change this paper would present the accurate ice motion observation of mountain glacier in eastern part of wks by the refined pixel tracking method with phased array type l band synthetic aperture radar images acquired on december 13 2008 and january 28 2009 the standard deviation values in nonglacial area before after topographic effect compensation are 0 61 and 0 43 m respectively during 46 day temporal interval in addition the terrain almost is a determining factor of ice velocity distribution in study area because the elevation of topography is generally shown to be positive correlated with glacier surface velocity along the central line furthermore with estimated detailed glacier surface movement distribution pattern we found that the continental glaciers were actively moving with spatially variable ice motion while the icecaps maintain the stable status without apparent motion on most part of surface therefore the refined sar based pixel tracking method including topographic effect compensation operation provides a useful and robust tool to map and measure the glacier motion in mountain area with complex terrain

establishing statistical confidence in cortex ratios within and among lithic assemblages a case study of the middle paleolithic of southwestern france abstract recent studies have demonstrated the usefulness of the cortex ratio for quantifying the cortex composition in lithic assemblages and as a viable index of prehistoric artifact transport yet the lack of means for assigning statistical confidence to archaeologically observed cortex ratios inhibits the approach s utility for objective comparisons and interpretation here we derive statistical confidence for archaeological cortex ratios through monte carlo and resampling techniques experimental data with known geometric properties and measured cortex values were employed as a reference for attaching a probability to an archaeological assemblage s cortex ratio the method is demonstrated on assemblages from the middle paleolithic sites of roc de marsal pech de l aze iv and combe capelle bas in southwestern france

the complementarity of luminescence dating methods illustrated on the mousterian sequence of the roc de marsal a series of reindeer dominated quina mousterian layers dated to mis 3 abstract located in southwest france roc de marsal is a cave with a rich mousterian stratigraphic sequence the lower part of the sequence layers 9 5 are characterized by assemblages dominated by levallois lithic technology associated with composite faunal spectra including red deer roe deer and reindeer that shows a gradual increase in the frequency of reindeer the top of the sequence layers 4 2 are characterised instead by quina lithic technology both in terms of technology and typology with the faunal remains dominated by reindeer roc de marsal thus provides a very interesting case study to place behavioural changes in a context of changing climates and environments in western europe during the late pleistocene to link the occupations at roc de marsal with global and regional climatic conditions known independently a robust chronology is needed with this aim in mind we applied three luminescence dating methods tl osl and irsl on different minerals flint quartz and k feldspar extracts here the results of two of these methods are presented in detail tl and osl and compared with preliminary irsl data at roc de marsal a comparison of methods was necessary to overcome a complex sedimentary history with very heterogeneous dose rate distributions both at the beta mm and gamma dm dose rate scales the results indicate that the lower levallois layers are dated to 65 70 ka while overlying quina layers are dated to 49 ka these ages for the lower layers fit well with some models that place mixed faunal assemblages in the initial mis 4 however while the quina ages overlap with several other quina assemblages from the region they place the reindeer dominated fauna well after the peak cold of mis 4 and suggest a more extended and complex period of contemporaneous lithic techno complexes than posited by some current models

heated flint tl dating for gruta da oliveira portugal dosimetric challenges and comparison of chronometric data the mousterian stratigraphy of gruta da oliveira torres novas portugal contains one of the latest occupations by neanderthals on the iberian peninsula thermoluminescence tl dates on heated flints were obtained for layers 13 and 14 and compared with the radiocarbon charcoal and burnt bone and u th secondary carbonates dating results available for those layers and the succession as a whole as the internal dose rates are very low the tl age estimates are very dependent on the external dose rates which show significant variation including indications of spatial patterning through close inspection of the radiation geometries of samples and dosemeters the appropriate gamma dosimetry is identified and the weighted mean tl ages 1 calculated accordingly are 55 7 ka for layer 13 and 77 8 ka for layer 14 these ages are stratigraphically consistent with the radiocarbon chronology for layers 9 11 and with the termini ante and post quem provided by u series dating for the beginning and end of the accumulation of the deposits the tl results corroborate that all radiocarbon dates below layer 11 are minimum ages only and given the constraints derived from the proxy data available place layer 13 and 14 post mis 5 sample as well as dosemeter numbers are low at gruta da oliveira which limits the precision of tl dating of a prehistoric human activity further refinement of the chronostratigraphy will be based on u series dating of non human related interstratified secondary carbonates

large fluctuations in speed on greenland s jakobshavn isbrae glacier it is important to understand recent changes in the velocity of greenland glaciers because the mass balance of the greenland ice sheet is partly determined by the flow rates of these outlets jakobshavn isbrae is greenland s largest outlet glacier draining about 6 5 per cent of the ice sheet area and it has been surveyed repeatedly since 1991 ref 2 here we use remote sensing data to measure the velocity of jakobshavn isbrae between 1992 and 2003 we detect large variability of the velocity over time including a slowing down from 6 700 m yr 1 in 1985 to 5 700 m yr 1 in 1992 and a subsequent speeding up to 9 400 m yr 1 by 2000 and 12 600 m yr 1 in 2003 these changes are consistent with earlier evidence for thickening of the glacier in the early 1990s and rapid thinning thereafter our observations indicate that fast flowing glaciers can significantly alter ice discharge at sub decadal timescales with at least a potential to respond rapidly to a changing climate

multistage mineralization at the hypozonal sao sebastiao gold deposit pitangui greenstone belt minas gerais brazil abstract sao sebastiao is a recently discovered archean gold deposit at the northwesternmost part of the quadrilatero ferrifero qf southern sao francisco craton brazil the gold ore is strata confined in two levels of banded iron formation bif of the basal stratigraphic unit in the pitangui greenstone belt 2 8 ga pitangui is correlated to the widely known rio das velhas greenstone belt which hosts several orogenic gold deposits such as the world class cuiaba the gold mineralization at sao sebastiao is associated to replacement style sulfidation over magnetite where the main developed phases are pyrrhotite chalcopyrite arsenopyrite pyrite and arsenian pyrite native au occurs as inclusions in pyrrhotite formed at dilatation domains e g breccias fold hinges during compressional events rio das velhas orogeny at 2 8 2 75 ga but mainly as inclusions in late to post kinematic pyrite and arsenopyrite as fracture infills in arsenopyrite and in contact with gangue minerals electron microprobe analyses in arsenopyrite reveal a 465 560 c precipitation temperature interpreted from as atomic percentage and indicate that high temperature fluids were active after the deformational event the temperature increase caused the incorporation of la icp ms detected lattice bound ni and co in arsenian pyrite and arsenopyrite related to the mafic ultramafic signature of boundary rocks high temperature conditions are supported by pyrite and iss intermediate solid solution in the cu fe s system formation at 600 c and melting derived textures resulting from the precipitation of bi and as melts typical of amphibolite facies environments with high fs2 whole rock geochemical assays of drill core samples display two clear trends on ag bi cu vs au binary plots and on principal component analysis results the trends are a product of the heterogeneous spatial distribution of melts and high temperature fluids melting features and superposition of mineralization styles are common in hypozonal gold deposits experiencing higher heat influx at sao sebastiao the thermal effect is likely related to the 2 7 ga granitic intrusions that surround the pitangui belt sao sebastiao shows distinct characteristics than those described for the mesozonal gold deposits in the rio das velhas greenstone belt and may depict the deeper roots of the qf gold system

glacier surface velocities in alpine terrain from optical satellite imagery accuracy improvement and quality assessment the worldwide retreat of mountain glaciers has important consequences for the water food and power supply of large and densely populated areas in south and central asia successful mitigation of the hydrological impacts on societies as well as assessing glacier related hazards require large scale monitoring of glacier dynamics however detailed glaciological data from the asian highlands are lacking due to its size and difficult accessibility we have applied a novel technique for precise orthorectification co registration and sub pixel correlation of advanced spaceborne thermal emission and reflection radiometer aster satellite imagery to derive surface velocities of himalayan glaciers our approach allows for the correction of offsets due to attitude effects and sensor distortions as well as elevation errors if a digital elevation model dem from the shuttle radar topography mission srtm was used for orthorectification after post processing the error on the displacements is on the order of 2 4 m per correlation translated into annual velocities this error is reduced increased when the correlated images are more less than a year apart through application of a filtering procedure and several quality tests the consistency of the results is validated to provide confidence in the remotely sensed velocity measurements despite the lack of ground control this novel approach allows fast easy and economically viable acquisition of detailed glaciological data in areas of difficult access and provides a means for large scale monitoring of glaciers in high mountainous terrain

tibetan plateau river incision inhibited by glacial stabilization of the tsangpo gorge much attention has focused on how and when the tibetan plateau formed but far less research has been done on the controls on river incision into the plateau itself oliver korup and david montgomery address this issue which also relates to the question of why the tibetan plateau is still there at all despite hosting one of the deepest gorges on earth the plateau edge is extremely well defined and according to widely accepted stream power theory should be heavily dissected by one of asia s most powerful rivers the yarlung tsangp or yarlung zangbo korup and montgomery propose that the southeastern edge of the plateau was preserved in part by the presence of glaciers that were large enough during the holocene to stall aggressive river downcutting along the plateau margin a considerable amount of research has focused on how and when the tibetan plateau formed in the wake of tectonic convergence between india and asia1 although far less enquiry has addressed the controls on river incision into the plateau itself2 widely accepted theory3 predicts that steep fluvial knick points river reaches with very steep gradients in the eastern himalayan syntaxis at the southeastern plateau margin should erode rapidly4 driving a wave of incision back into the plateau preservation of the plateau edge thus presents something of a conundrum that may be resolved by invoking either differential rock uplift matching erosional decay5 6 7 or other mechanisms for retarding bedrock river incision8 9 in this region where high stream power excludes the potential for aridity as a simple limit to dissection of the plateau10 here we report morphologic evidence showing that quaternary depression of the regional equilibrium line altitude where long term glacier mass gain equals mass loss was sufficient to repeatedly form moraine dams on major rivers such damming substantially impeded river incision into the southeastern edge of the tibetan plateau through the coupled effects of upstream impoundment and interglacial aggradation such glacial stabilization of the resulting highly focused river incision centred on the tsangpo gorge could further contribute to initiating and accentuating a locus of rapid exhumation known as tectonic anaeurysm6

thermoluminescence electron spin resonance and14c dating of the late middle and early upper palaeolithic site of geisenklosterle cave in southern germany abstract thermoluminescence tl dating of burnt silex flint chert electron spin resonance esr dating of teeth and 14 c accelerator mass spectrometry ams dating of bones has been carried out on samples from the late middle palaeolithic and early upper palaeolithic levels of the geisenklosterle cave south germany esr dating on tooth enamel from the upper part of level iv which contains a very small undefined middle palaeolithic assemblage yields a mean age of 43 3 4 ka the overlying early aurignacian level iii is placed in the hengelo interstadial by palaeoecological analysis 14 c ams results give a mean age of 38 4 0 85 ka whereas a mean age of 40 2 1 5 ka is obtained by tl of burnt silex confirming the correlation of the early aurignacian level with the hengelo interstadial in oxygen isotope stage ois 3 14 c ams of bone samples from the aurignacian level ii resulted in a mean age of 33 5 0 35 ka whereas the tl ages on burnt silex are again older at c 37 ka these tl results can be taken as an indication of the age underestimation by 14 c caused by the lack of calibration the aurignacian level contains some of the most elaborate symbolic representations from the upper palaeolithic artwork of comparable quality is radiocarbon dated to 31 000 ka at the grotte chauvet thus being significantly younger furthermore the geisenklosterle cave provides evidence of the existence of early rock art in central europe although only small pieces survived erosion the gravettian assemblage of the geisenklosterle cave yielded a mean 14 c ams age of 29 0 0 25 ka

measuring two dimensional movements using a single insar pair 1 we present a new method to extract along track displacements from insar data based on split beam insar processing to create forward and backward looking interferograms the phase difference between the two modified interferograms provides the along track displacement component thus from each conventional insar pair we extract two components of the displacement vector one along the line of sight the other in the along track direction we analyze the precision of the new method by comparing our solution to gps and offset derived along track displacements in interferograms of the 1999 hector mine earthquake the rms error between gps displacements and our results ranges from 5 to 8 8cm our method is consistent with along track displacements derived by pixel offsets which are limited to 12 15cm precision the theoretical precision of the new method depends on snr and coherence for a signal to noise ratio of 30 the expected precisions are 3 11cm for coherence of 0 8 0 4 respectively

late twentieth century changes in glacier extent in the ak shirak range central asia determined from historical data and aster imagery 1 global analysis of glacier regimes reveals widespread wastage since the late 1970s with a marked acceleration in the late 1980s we investigate changes in the heavily glacierized ak shirak range central tien shan plateau 43 n 75 e using air photo mapping surveys 1943 and 1977 an aster imagery 2001 and long term glaciological and meteorological observations the wasting of the ak shirak glacier system features a decrease in average glacier size and an increase in the area of outcrops a small shrinkage during 1943 1977 was followed by a greater than 20 reduction during 1977 2001 in response to increases in summer and annual air temperature and decreases in annual precipitation

large surface velocity fluctuations of biafo glacier central karakoram at high spatial and temporal resolution from optical satellite images despite global warming and unlike their himalayan neighbours glaciers in the karakoram mountains do not show signs of significant retreat here we report high velocity variations of biafo glacier central karakoram which occurred between 2001 and 2009 and which indicate considerable dynamics in its flow behaviour we have generated a dense time series of glacier surface velocities based on cross correlation of optical satellite images which clearly shows seasonal and interannual velocity variations reaching 50 in some places the interannual velocity variations resemble the passing of a broad wave of high velocities with peak velocities during 2005 and some diffusion down glacier over a period of at least 4 years high interannual velocity variations are also observed at other glaciers in the vicinity suggesting a common cause although these appear to partly comprise longer acceleration phases analysis of weather station data provides some indications of meteorological conditions that could have promoted sustained sliding events during this period but this does not explain the wave like nature of the acceleration at biafo glacier and the regular protracted velocity changes

hydrous sulfide melting experimental evidence for the solubility of h2oin sulfide melts the effect of h 2 o on sulfide melting temperatures has been investigated in the fes pbs zns system at 1 5 gpa revealing that the addition of h 2 o results in a 35 c drop in melting temperature from 900 to 865 c in addition to the melting point depression the solubility of h 2 o is confirmed by the presence of vesicles in the quenched melt no oxide phases were present in any of the run products ruling out oxidation as a cause of the melting point depression confirmation of the solubility of h 2 o in sulfide melts is consistent with the recent suggestion by mungall and brenan 2003 of a magmatic origin for halogen rich alteration associated with magmatic sulfide ore deposits as the hydrous component of the alteration may similarly originate in the fractionating sulfide melt anatectic sulfide melts could be expected to contain more h 2 o than magmatic sulfide melts owing to the lack of a parental silicate melt that buffers the h 2 o content of magmatic sulfide melts fluids expelled from the cooling anatectic melts such as that present during granulite facies metamorphism of sulfide deposits at broken hill australia may have been responsible for associated retrograde hydrothermal alteration

glaciological advances made with interferometric synthetic aperture radar spaceborne interferometric synthetic aperture radar insar techniques for measuring ice flow velocity and topography have developed rapidly over the last decade and a half revolutionizing the study of ice dynamics spaceborne interferometry has contributed to major progress in many areas of glaciological study by providing the first comprehensive measurements of ice stream flow velocity over the major outlets of greenland and antarctica revealing that ice stream and outlet glacier flow can change rapidly months to years improving understanding of several ice sheet and ice shelf processes providing velocity for flux gate based mass balance assessment mapping flow of mountain glaciers and capturing the geomorphic traces of past ice flow we review the basic technique development the measurement characteristics and the extensive set of results yielded by these measurements