the impact of topographical parameters to the glaciation and glacial retreat on mount agri ararat the controls of topography on glacial changes are crucial because the heterogeneity in glacial distribution is mainly due to the topography it is possible to see clearly the topographical effects on glacier distributions on the agri glacier as it is the highest region relative to its immediate surroundings so the glacier region is not under the influence of topography of other regions this paper investigates and aims to determine the effects of topographic characteristics on glaciation and melting regions on agri glacier the study was carried out using landsat satellite data in august 1987 1989 1998 2013 and 2015 glacier boundaries delineated with both band ratio technique and normalize difference snow index for each year topographical characteristics of glaciation and melting zones were analyzed regarding aspect slope elevation and direction all analyses were performed by spatial statistics based on the geographic information system as a result of the study the significant spatial correlation was observed between topographic parameters and glacier distributions therefore the topographic structure has a direct impact on the glaciation and melting in comparison with aspect and slope parameters elevation and direction are more important parameters for prediction of potential melting zones it was predicted that the glacier area loss will be higher at lower elevations of both the eastern and southern parts of the glacier and there will be no glacier in these directions soon

10 be in ice at vostok antarctica during the last climatic cycle we have previously reported accelerator mass spectrometer measurements of the cosmogenic isotope 10be half life 1 5 myr in an 906 m ice core recovered at dome c antarctica1 in addition to an enhanced concentration during a period of reduced solar activity maunder minimum ad 1645 1715 2 we found substantially increased concentrations during that part of the core corresponding to the last ice age both effects have been confirmed and extended in greenland ice cores3 4 the recovery of a 2 083 m ice core at vostok antarctica5 together with an extended oxygen isotope chronology reported elsewhere in this issue6 permits an extension of 10be studies over the whole of the last climatic cycle 125 kyr we report here such measurements which show an excellent correlation with the oxygen isotope and thus presumably climate record over the whole of this period the results imply that precipitation rates in the antarctic during the last interglacial were similar to those of the holocene but were roughly halved during the last glaciation

the mass balance of circum arctic glaciers and recent climate change the sum of winter accumulation and summer losses of mass from glaciers and ice sheets net surface mass balance varies with changing climate in the arctic glaciers and ice caps excluding the greenland ice sheet cover about 275 000 km2of both the widely glacierized archipelagos of the canadian norwegian and russian high arctic and the area north of about 60 n in alaska iceland and scandinavia since the 1940s surface mass balance time series of varying length have been acquired from more than 40 arctic ice caps and glaciers most arctic glaciers have experienced predominantly negative net surface mass balance over the past few decades there is no uniform recent trend in mass balance for the entire arctic although some regional trends occur examples are the increasingly negative mass balances for northern alaska due to higher summer temperatures and increasingly positive mass balances for maritime scandinavia and iceland due to increased winter precipitation the negative mass balance of most arctic glaciers may be a response to a step like warming in the early twentieth century at the termination of the cold little ice age arctic ice masses outside greenland are at present contributing about 0 13 mm yr 1to global sea level rise

the tectonic implications of asymmetrically zoned plutons abstract asymmetrically zoned plutons have been mapped in many parts of the world and whereas many of these are asymmetrical for reasons unrelated to regional tectonic environment there are large areas in which the majority of asymmetric plutons are asymmetric in the same direction in these domains of asymmetry either the mechanisms of emplacement or post emplacement deformation have produced a systematic exposure orientation recognition of these domains may lead to discovery of the tectonic mechanisms responsible for systematic orientation ultimately domains of pluton asymmetry may serve to identify the manner of tectonic emplacement or post emplacement deformation

remote sensing of glacier change in west greenland accounting for the occurrence of surge type glaciers automated glacier mapping from thresholded band ratios of multispectral satellite data is a well established technique to update glacier inventories over large and remote regions the local glaciers and ice caps on greenland are of particular interest for such efforts as they have been only partly mapped mainly during the 1940s 60s and their potential contribution to global sea level rise could be large here we use three landsat etm scenes from 2001 covering disko island qeqertarsuaq and the nuussuaq and svartenhuk peninsulas west greenland to map the glacier extent in 2001 of 1172 entities we also manually digitize little ice age lia extents from clearly visible trimlines for a subsample of 500 entities in this region with numerous surge type glaciers the related area change calculation is challenging and we consider different samples with and without known surging glaciers for the three regions the mean area changes are 28 20 and 23 respectively when known surge type glaciers are excluded the glaciers on smaller islands and peninsulas closer to the margin of the ice sheet show a lower mean area change of 15 moreover lower 16 and upper 21 bounds are calculated for the overall area changes in the entire region between the lia and 2001 using different upscaling assumptions cumulative length changes since the lia are found to be slightly lower for surge type glaciers

dating the onset of variscan crustal exhumation in the core of the bohemian massif new u pb single zircon ages from the high k calc alkaline granodiorites of the blatna suite central bohemian plutonic complex abstract the variscan central bohemian plutonic complex crops out between the upper crustal tepla barrandian and the high grade moldanubian units bohemian massif much of the complex is made up of calc alkaline plutonic rocks 1 the geochemically more primitive na rich 354 4 ma sazava suite which was emplaced syntectonically during regional shortening 2 the younger more evolved potassic blatna suite which records both the shortening along its nw contact and the onset of normal shearing related to exhumation of the moldanubian unit to the se new ion microprobe u pb zircon ages for the high k calc alkaline blatna suite pinpoint this major switch in the tectonic regime both blatna and kozarovice granodiorites 346 2 ma and 347 2 ma 2 were generated by melting of heterogeneous crust and were emplaced contemporaneously to form the blatna composite pluton from age spectra preserved in inherited zircons and whole rock sr nd isotope signatures the likely crustal sources for the magmas were immature greywackes rich in neoproterozoic 615 10 ma kozarovice or late cambrian early ordovician 492 4 ma blatna volcanogenic detritus an additional important petrogenetic process was variable mixing with enriched mantle derived monzonitic magmas which may also have supplied the extra heat for crustal anatexis supplementary material analytical techniques selected whole rock major and trace element geochemical analyses and u th pb data are available at http www geolsoc org uk sup18391

perspectives on the production of a glacier inventory from multispectral satellite data in arctic canada cumberland peninsula baffin island the consequences of global warming on land ice masses are difficult to assess in detail as two dimensional glacier inventory data are still missing for many remote regions of the world as the largest future temperature increase is expected to occur at high latitudes the glaciers and ice caps in the arctic will be particularly susceptible to the expected warming this study demonstrates the possibilities of space borne glacier inventorying at a remote site on cumberland peninsula a part of baffin island in arctic canada thereby providing glacier inventory data for this region our approach combines landsat etm and terra aster satellite data an aster derived digital elevation model dem and geographic information system based processing we used thresholded ratio images from etm bands 3 and 5 and aster bands 3 and 4 for glacier mapping manual delineation of little ice age trimlines and moraines has been applied to calculate area changes for 225 glaciers yielding an average area loss of 11 a size distribution has been obtained for 770 glaciers that is very different from that for alpine glaciers numerous three dimensional glacier parameters were derived from the aster dem for a subset of 340 glaciers the amount of working time required for the processing has been tracked and resulted in 5 min per glacier or 7 years for all estimated 160 000 glaciers worldwide

oxygen isotope composition of living neogloboquadrina pachyderma sin in the arctic ocean data from the nansen basin of the arctic ocean are used to investigate the habitat and conditions under which the polar planktic foraminifer neogloboquadrina pachyderma sin calcifies the vertical distribution of 18o values of net sampled speciments together with their abundances and proportion of calcification are compared with 18o values from both water samples and foraminiferal tests from core top sediments within the nansen basin the average depth of habitat of n pachyderma sin changes from about 150 m in the southern part to about 80 m in the northern the average depth of calcification however in both regimes varies between 100 and 200 m water depth 18o data from net sampled n pachyderma sin are directly reflected in the core top sediment data but compared to equilibrium calcite 18o values derived from measurements of the ambient water a consistent offset of about 1 over all depth intervals is observed while in the southern part of the nansen basin advection through fram strait of planktic foraminifers from further south may play a role the data from the northern part of the nansen basin give clear evidence that the observed offset in 18o values is caused by a vital effect of n pachyderma sin

gahnite chrysoberyl and beryl co occurrence as accessory minerals in a highly evolved peraluminous pluton the belvis de monroy leucogranite caceres spain abstract gahnite znal 2 o 4 chrysoberyl beal 2 o 4 and beryl be 3 al 2 si 6 o 18 have been found as accessory minerals in the external highly fractionated leucogranitic unit within the hercynian reversely zoned belvis de monroy pluton westernmost part of the montes de toledo batholith caceres spain the highly felsic sio 2 72 wt and peraluminous acnk 1 2 character of this leucogranite together with the high content of some incompatible elements f li b and p seems to be a primary consequence of fractional crystallization in a magmatic closed system the high be contents and zn fe total ratio 0 01 are relevant factors which have favoured the precipitation of these minerals moreover the si al p b and f activities might be high favouring the magmatic crystallization of such exotic mineral phases together with be rich cordierite f rich micas sillimanite and al rich phosphates in fact the interplay between the silica and alumina activities likely controls the stabilization and the preferential crystallization of gahnite chrysoberyl or beryl chrysoberyl assemblages in mm sized microdomains the p t crystallization conditions are constrained by the muscovite and sillimanite stability fields and the minimum granite al 2 o 3 saturated solidus and have been estimated at temperatures between 670 and 700 c and pressures between 1 and 2 kbar

milankovitch theory of ice ages hypothesis of ice sheet linkage between regional insolation and global climate abstract j d hays j imbrie and n j shackleton 1976 science 194 1121 1132 showed that the astronomical theory explained many features of late quaternary ice age climates but they did not specify the physical mechanisms involved here it is proposed that interlocked variations of ice sheet heat sinks in both polar hemispheres amplified and transmitted milankovitch summer half year insolation changes a version of the astronomical theory between 45 and 75 n into the globally synchronous climate changes recorded in geologic records it is suggested that late quaternary ice sheets had terrestrial components grounded above sea level melting margins fluctuations controlled by climate and marine components grounded below sea level drained largely by ice streams limited melting margins fluctuations controlled primarily by sea level and secondarily by climate interior surface elevations coupled to downdraw through ice streams northern hemisphere ice sheets were largely marine with minor melting margins in the arctic and terrestrial with major melting margins in the midlatitudes west antarctic and peripheral east antarctic ice was marine based and lacked melting margins because of their geographic array these terrestrial and marine components formed an ice sheet system whose variations were coupled on a global scale milankovitch summer isolation changes near midlatitude northern hemisphere melting margins controlled most variations of this system because advance or retreat of melting margins initiated concurrent eustatic sea level change such sea level change afforded the critical interlocking mechanism between terrestrial and marine components because it forced simultaneous expansion or contraction of marine margins in both polar hemispheres this initiated an amplifying feedback loop among all marine components and influenced interior downdraw through ice streams arctic summer insolation change was less important because northern melting margins were relatively minor its greatest influence was on surface ablation of ice streams that controlled interior downdraw this affected eustatic sea level and activated global linkage of marine sectors by analogy with present day antarctica late quaternary ice sheets were enormous planetary heat sinks due to their reflective and radiative surface characteristics it is suggested that the effectiveness of these ice sheet heat sinks varied with their areal extent and interior surface elevation thus it is postulated that concurrent growth or decay of these interlocked ice sheet heat sinks in both polar hemispheres served as the global amplifier of regional milankovitch summer insolation

a new glacier inventory on southern baffin island canada from aster data ii data analysis glacier change and applications despite its large area covered by glaciers and ice caps detailed glacier inventory data are not yet available for most parts of baffin island canada automated classification of satellite data could help to overcome the data gaps along track stereo sensors allow the derivation of a digital elevation model dem and glacier outlines from the same point in time and are particularly useful for this task while part i of this study describes the remote sensing methods in part ii we present an analysis of the derived glacier inventory data for 662 glaciers and an application to glacier volume and volume change calculations among other things the analysis reveals a mean glacier elevation of 990 m with a weak dependence on aspect and a close agreement of the arithmetic mean with the statistical mean elevation as derived from the dem a strong scatter of mean slope is observed for glaciers 1 km2 and the derived glacier thickness differs by a factor of two for glaciers of the same size for the period from about 1920 to 2000 the relative area change is 12 5 264 glaciers with a strong dependence on glacier size mean mass loss as derived from volume changes is about 0 15mw e a 1

sr nd isotopic constraints on the petrogenesis of the central bohemian pluton czech republic the sr nd isotopic data for selected granitoids of the central bohemian pluton show a broad negative correlation with the total range of 87sr 86sr 330 0 7051 0 7129 and nd330 0 2 to 8 9 the older intrusions have more depleted sr nd compositions and calc alkaline geochemistry sazava suite whereas the younger intrusions shift towards k rich calc alkaline blatna suite and shoshonitic rocks icany and certovo b emeno suites with more evolved isotopic signatures the distribution of the data is interpreted as reflecting a diversity of sources and processes rather than a single progressive crustal contamination trend the sazava suite could have originated by partial melting of metabasites or of a mantle source with an isotopic composition close to bulk earth or by hybridization of crustally derived tonalitic and mantle derived magmas variation within the blatna suite is modelled by mixing between a moderately enriched 87sr 86sr 330 0 708 nd330 3 mantle component with either an isotopically evolved metasedimentary component or with more evolved magmas of the suite the icany suite was most probably produced by partial melting of peraluminous lithologies possibly of the adjacent moldanubian unit the certovo b emeno suite evolved from strongly enriched mantle derived magmas 87sr 86sr 330 0 7128 end330 7 either through closed system fractional crystallization or interaction with magma corresponding to leucogranites of the central bohemian pluton

glacier volume estimation on cascade volcanoes an analysis and comparison with other methods during the 1980 eruption of mount st helens the occurrence of floods and mudflows made apparent a need to assess mudflow hazards on other cascade volcanoes a basic requirement for such analysis is information about the volume and distribution of snow and ice on these volcanoes an analysis was made of the volume estimation methods developed by previous authors and a volume estimation method was developed for use in the cascade range a radio echo sounder carried in a backpack was used to make point measurements of ice thickness on major glaciers of four cascade volcanoes mount rainier washington mount hood and the three sisters oregon and mount shasta california these data were used to generate ice thickness maps and bedrock topographic maps for developing and testing volume estimation methods subsequently the methods were applied to the unmeasured glaciers on those mountains and as a test of the geographical extent of applicability to glaciers beyond the cascades having measured volumes two empirical relationships were required in order to predict volumes for all the glaciers generally for glaciers less than 2 6 km in length volume was found to be estimated best by using glacier area raised to a power for longer glaciers volume was found to be estimated best by using a power law relationship including slope and shear stress the necessary variables can be estimated from topographic maps and aerial photographs

on the late pleistocene ocean geochemistry and circulation a box model of the atmosphere and ocean was developed to investigate how geochemical distributions extant during the late pleistocene may have come about the model simulates the regional distribution of calcium carbonate dissolution as well as the chemical oceanography and atmospheric co2 13c and radiocarbon if the downward biological flux of particulate carbon increases by a factor of 2 to 3 in the antarctic and if this increase is combined with a relative increase of the atlantic sector antarctic bottom water aabw versus north atlantic deep water nadw source ratio from 1 3 to about 2 1 then the model predicts several changes that seem to be recorded in the sedimentary record as follows 1 a global redistribution of nutrients and 12c from the intermediate to deep water takes place with the atlantic intermediate water phosphate decreasing 0 6 mole kg 1 and the 13c increasing 0 3 to 0 5 2 the dissolved oxygen level of the deep sea is reduced from an average of about 180 to 70 mole kg 1 but the intermediate water oxygen declines only a small amount 3 the decrease in intermediate water nutrient concentration results in lower average organic carbon and calcium carbonate production in the warm surface ocean 4 the atmospheric co2 decreases by 90 to 110 ppm 5 initially a global increase in calcium carbonate dissolution occurs which is followed by a relaxation toward better preservation than exists for the present ocean in the model in this paper the reduction of nadw by itself does not produce these effects rather the nutrient decrease that does occur is found mostly in north pacific intermediate water and the model atmospheric co2 decrease is only 10 to 30 ppm it is observed that 92 of the atmospheric co2 change takes place according to a 200 year time constant in the model this corresponds to the response time of the upper ocean and atmosphere to a change in the stationary state atmospheric pco2 thus according to this model the time lag between the nutrient based cause and the atmospheric co2 response is not expected to be particularly large

the distribution and flow characteristics of surge type glaciers in the canadian high arctic a systematic review of 1959 60 aerial photography and 1999 2000 landsat 7 imagery has identified 51 surge type polythermal glaciers in the canadian high arctic these were identified from the presence of features such as looped medial moraines intense folding visible at the surface rapid terminus advance heavy surface crevassing and high surface velocities these observations suggest that surging glaciers are much more common than previously believed in the canadian high arctic where only six surge type glaciers have previously been described of the 51 surge type glaciers identified in this study 15 were observed in the active phase in the 1959 60 and or 1999 2000 imagery the most dramatic advances have occurred on western axel heiberg island where iceberg good friday bay and airdrop glaciers have all advanced by 4 7 km between1959 and 1999 for glaciers with repeat landsat 7 coverage from 1999 and 2000 image correlation software was used to determine the magnitude and spatial distribution of surge velocities for example mittie glacier on manson icefield was moving at a rate of up to 1 kma over a distance of at least 25 km back from its terminus the terminus of this glacier has advanced by at least 4 km since 1959 and the glacier was observed to be heavily crevassed during overflights in april 2000 with clear signs of surface lowering of 10 25 m indicated by a strandline

diatom distribution and paleoceanographic reconstruction in the southern ocean present and last glacial maximum abstract diatom assemblage and preservational data are used to reconstruct paleoceanographic conditions at the last glacial maximum 18 000 yrs bp in the southern ocean from these data the following points can be made about the last glacial maximum in this region 1 contraction and slight northern shift of the belt of well preserved diatoms appears to be related to the northward shift of late spring early summer sea ice cover 2 presence of open ocean though poorly preserved diatom assemblages to the south of this belt strongly suggest that during many summers large areas of the southern ocean were ice free 3 the distribution of thenitzschia kerguelensis factor both in surface sediments and at the last glacial maximum indicates that the gyre systems particularly the weddell gyre were intensified during glacial times 4 although data are sparse in the higher latitude south atlantic there is an indication that the weddell polynya also existed during glacial times although it was shifted a few degrees northward

magmatic to solid state fabrics in syntectonic granitoids recording early carboniferous orogenic collapse in the bohemian massif abstract the 354 336 ma central bohemian plutonic complex is a variscan magmatic arc that developed in the central bohemian massif in response to subduction of the saxothuringian lithosphere beneath the tepla barrandian microplate magmatic to solid state fabrics in the most voluminous portion of this arc the 346 ma blatna pluton record two superposed orogenic events dextral transpression associated with arc parallel stretching and arc perpendicular shortening and normal shearing associated with exhumation of the high grade core of the orogen moldanubian unit this kinematic switch is an important landmark in the evolution of this segment of the variscan belt for it marks the cessation of subduction related compressive forces in the upper crust giving way to gravity driven normal movements of the tepla barrandian hanging wall block relative to the high grade moldanubian footwall we use thermal modeling to demonstrate that the emplacement of huge volumes of arc magmas and their slow cooling produced a thermally softened domain in the upper crust and that the magmatic arc granitoids may have played a major role in initiating the orogenic collapse in the bohemian massif through lubrication and reactivation of a pre existing lithospheric boundary and decreasing the overall strength of the rigid orogenic lid

glaciological conditions in seven contrasting regions estimated with the degree day model we apply the degree day model to seven glacial regions that offer contrasting conditions and are well documented in the world glacier inventory the regions are axel heiberg island in arctic canada svalbard northern scandinavia southern norway the alps the caucasus and new zealand we estimate the average equilibrium line altitude ela for each half degree latitude longitude grid square from the median elevations of glaciers within the square and we extrapolate temperature from the uea cru climate research unit of the university of east anglia gridded climatology using the degree day model we calculate annual accumulation at the ela equal to ablation at the ela and other quantities like summer mean temperature length of melt season balance gradients and the sensitivity of mass balance to temperature and or precipitation changes glaciers can be characterized on a scale from cold dry axel heiberg island to warm wet new zealand corresponding to the contrast between maritime and continental climates mass balance sensitivities to temperature and or precipitation changes are relatively small for dry cold climate and relatively high for warm wet climate we could extend the approach to other glacier regions but we note that there are large areas for which ela data are not available as they are still not covered by the world glacier inventory

direct dating of the oxygen isotope record of the last deglaciation by 14c accelerator mass spectrometry major trends of quaternary global climate are reflected in the continental ice volume changes which have been reconstructed by oxygen isotope analysis1 2 18o records from deep sea sediments show that the net glacial build up occurs relatively slowly3 but that the end of an ice age occurs quickly in less than 10 000 yr implying a nonlinear response4 5 to simple milankovitch theory6 the latter observation suggests that the cause of the most recent deglaciation was the maximum in summer calorific radiation at the upper latitudes of the northern hemisphere centred around 11 000 yr ago a view supported by early studies7 later work has produced conflicting dates the main source of confusion being problems with obtaining accurate and reliable dates here by using accelerator mass spectrometry we have measured 14c for various species of foraminifera to produce a reliable timescale for the oxygen isotope record our results show that at the end of the last ice age continental ice sheets began to melt more than 4 000 yr before the northern hemisphere maximum of summer calorific radiation

13c record of benthic foraminifera in the last interglacial ocean implications for the carbon cycle and the global deep water circulation the 13c 12c ratios of upper holocene benthic foraminiferal tests genera cibicides and uvigerina of deep sea cores from the various world ocean basins have been compared with those of the modern total carbon dioxide tco2 measured during the geosecs program the 13c difference between benthic foraminifera and tco2 is 0 07 0 04 for cibicides and 0 83 0 07 for uvigerina at the 95 confidence level 13c analyses of the benthic foraminifera that lived during the last interglaciation isotopic substage 5e about 120 000 yr ago show that the bulk of the tco2 in the world ocean had a 13c value 0 15 0 12 lower than the modern one at the 95 confidence level reflecting a depletion compared to the present value of the global organic carbon reservoir regional differences in 13c between the various oceanic basins are explained by a pattern of deep water circulation different from the modern one the antarctic bottom water production was higher than today during the last interglaciation but the eastward transport in the circumpolar deep water was lower

are strongly peraluminous magmas derived from pelitic sedimentary sources igneous compositions that require the presence of a phase more aluminous than biotite are here designated as strongly peraluminous ps such compositions are common but subordinate in felsic rocks and exceedingly rare in more mafic rocks the term s type has been applied to many igneous rocks based largely or even solely upon their ps compositions neglecting or placing less emphasis on other criteria for sedimentary parentage in chappell and white s i and s type classification system the s type designation was in fact initially restricted to granites which were thought to have been derived from a chemically mature strongly weathered pelitic shaly source application of chappell s and white s criteria together with others based upon isotopic and phase equilibria considerations leads to the following conclusions about ps igneous rocks worldwide 1 very few ps rocks are derived entirely from pelitic sources 2 a majority are derived largely from intermediate to felsic crustal sources including

ice rafted volcanic ash in the south atlantic sector of the southern ocean during the last 100 000 years abstract eucampia antarctica castr mangin abundance curves for two piston cores from the western agulhas basin southeast atlantic sector of the southern ocean were used to place volcanic glass shard and ice rafted debris abundance curves into a stratigraphic framework for the last 100 000 years a direct correlation is shown between increased abundance of e antarctica tephra and ice rafted debris low abundances are often characterized by calcareous sediment in the northern core peaks in abundance of e antarctica have been interpreted as an indication of glacial periods and the increased ice rafted debris and tephra during glacial periods is evidence for an ice rafted origin for the tephra microprobe geochemical analysis of volcanic glass shards provides no single distinct source for the ash the geochemical data is consistent but not definitive with a primary source in the scotia arc and a minor source from bouvet island between core correlations of geochemically fingerprinted dispersed tephra zones were not successful due to variability of glass shard geochemistry and limited sample size

origin of detrital fluxes in the southeast indian ocean during the last climatic cycles because of a close relationship between detrital flux variations and magnetic susceptibility ms flux ms cm 3 of bulk sediment multiplied by the linear sedimentation rate variations in the southeast indian basin of the southern ocean ms flux profiles have been used to examine the spatial and temporal detrital flux changes in this basin during the last climatic cycle results indicate a general increase in detrital material input during the coldest periods suggesting a widespread phenomenon at least on the basin scale mineralogical data geochemical data and 87sr 86sr isotopic ratios have been used to determine the origin and transport mechanisms responsible for increased detrital flux during glacial periods mineralogical and geochemical data show that these glacial highs are due to increases in both kerguelen crozet volcanic and antarctic detrital inputs the 87sr 86sr isotopic composition of the 45 m fraction indicates that the kerguelen crozet province contributes to at least 50 of the coarse particule input to the west this contribution decreases eastward to reach less than 10 these tracers clearly indicate that the crozet kerguelen province was a major source region of detrital in the western part of the basin during glacial times in contrast material of antarctic origin is well represented in the whole basin fine and coarse fractions because of the minor amount of coarse particles in the sediments volcanic particles from kerguelen and crustal particles from antarctica have most probably been transported by the antarctic bottom water current and or the circumpolar deepwater current during glacial periods as is the case today nevertheless the presence of coarse particles even in low amount suggests also a transport by ice rafting sea ice and icebergs originated from both kerguelen and antarctic sources however the relative importance of both hydrographic and ice rafting modes of transport cannot be identified accurately with our data during low sea level stands glacial maximum periods increasing instability and erosion of the continental platform and shallow plateaus could have resulted in a more efficient transfer of crustal and volcano detrital material to the southeast indian basin at the same time extension of the grounded ice shelves over the continental margins and increase in the erosion rate of the antarctic ice sheet could have induced a greater input of ice rafted detritus ird to southern ocean basins enhancement of the circumpolar deepwater current strength might have also carried a more important flux of detrital material from kerguelen however an increase in the bottom water flow is not necessarily required

low sea level rise projections from mountain glaciers and icecaps under global warming the mean sea level has been projected to rise in the 21st century as a result of global warming such projections of sea level change depend on estimated future greenhouse emissions and on differing models but model average results from a mid range scenario a1b suggests a 0 387 m rise by 2100 refs 1 2 the largest contributions to sea level rise are estimated to come from thermal expansion 0 288 m and the melting of mountain glaciers and icecaps 0 106 m with smaller inputs from greenland 0 024 m and antarctica 0 074 m here we apply a melt model and a geometric volume model to our lower estimate of ice volume and assess the contribution of glaciers to sea level rise excluding those in greenland and antarctica we provide the first separate assessment of melt contributions from mountain glaciers and icecaps as well as an improved treatment of volume shrinkage we find that icecaps melt more slowly than mountain glaciers whose area declines rapidly in the 21st century making glaciers a limiting source for ice melt using two climate models we project sea level rise due to melting of mountain glaciers and icecaps to be 0 046 and 0 051 m by 2100 about half that of previous projections

a proposed model for the formation of reversely zoned plutons based on a study of the lacorne complex superior province quebec the lacorne complex is a calc alkaline mass of archean age located in the abitibi region of quebec the complex can be subdivided into three zones the inner zone varies in composition from hornblende biotite gabbro breccia to monzonite with all rocks containing 5 modal quartz the outer zone rocks contain more than 5 modal quartz and range in composition from biotite hornblende quartz diorite to granodiorite the third zone consisting of muscovite biotite garnet leucomonzogranite is exposed only in the northwestern portion of the complex the transition between each zone is relatively abrupt but continuous based on 400 modal estimates of stained slabs and 107 whole rock and trace element analyses it is demonstrated that both the inner zone and the outer zone rocks are reversely zoned mafic cores are surrounded by more felsic borders various methods that could explain the observed geochemical trends are considered the data indicate that crystal liquid equilibria were maintained during cry

tectonic record magmatic history and hydrothermal alteration in the hercynian guerande leucogranite armorican massif france abstract the guerande peraluminous leucogranite was emplaced at the end of the carboniferous in the southern part of the armorican massif at the scale of the intrusion this granite displays structural heterogeneities with a weak deformation in the southwestern part whereas the northwestern part is marked by the occurrence of s c and mylonitic extensional fabrics quartz veins and pegmatite dykes orientations as well as lineations directions in the granite and its country rocks demonstrate both e w and n s stretching therefore during its emplacement in an extensional tectonic regime the syntectonic guerande granite has probably experienced some partitioning of the deformation the southwestern part is characterized by a muscovite biotite assemblage the presence of restites and migmatitic enclaves and a low abundance of quartz veins compared to pegmatite dykes in contrast the northwestern part is characterized by a muscovite tourmaline assemblage evidence of albitization and gresenization and a larger amount of quartz veins the southwestern part is thus interpreted as the feeding zone of the intrusion whereas the northwestern part corresponds to its apical zone the granite samples display continuous compositional evolutions in the range of 69 8 75 3 wt sio 2 high initial 87 sr 86 sr ratios and low e nd t values suggest that the peraluminous guerande granite a cnk 1 1 was formed by partial melting of metasedimentary formations magmatic evolution was controlled primarily by fractional crystallization of k feldspar biotite and plagioclase an20 the samples from the apical zone show evidence of secondary muscovitization they are also characterized by a high content in incompatible elements such as cs and sn as well as low nb ta and k rb ratios the apical zone of the guerande granite underwent a pervasive hydrothermal alteration during or soon after its emplacement u th pb dating on zircon and monazite revealed that the guerande granite was emplaced 309 7 1 3 ma ago and that a late magmatic activity synchronous with hydrothermal circulation occurred at ca 303 ma these new structural petrological and geochronological data presented for the guerande leucogranite highlight the interplay between the emplacement in an extensional tectonic regime magmatic differentiation and hydrothermal alteration and provide a general background for the understanding of the processes controlling some mineralization in the western european hercynian belt

application of inventory data for estimating characteristics of and regional climate change effects on mountain glaciers a pilot study with the european alps a parameterization scheme using simple algorithms for unmeasured glaciers is being applied to glacier inventory data to estimate the basic glaciological characteristics of the inventoried ice bodies and simulate potential climate change effects on mountain glaciers for past and potential climate scenarios glacier changes for assumed mass balance changes are calculated as step functions between steady state conditions for time intervals that approximately correspond to the characteristic dynamic response time a few decades of the glaciers in order to test the procedure a pilot study was carried out in the european alps where detailed glacier inventories had been compiled around the mid 1970s total glacier volume in the alps is estimated at about 130 km3 for the mid 1970s strongly negative mass balances are likely to have caused a loss of about 10 20 of this total volume during the decade 1980 90 backward calculation of glacier length changes using a mean annual mass balance of 0 25m w e a 1 since the end of the little ice age around 1850 ad gives considerable scatter but satisfactory overall results as compared with long term observations the total loss of alpine surface ice mass since 1850 can be estimated at about half the original value an acceleration of this development with annual mass losses of around 1 m a 1 or more as anticipated from ipcc scenario a for the coming century could eliminate major parts of the presently existing alpine ice volume within decades

a new glacier inventory for the svartisen region norway from landsat etm data challenges and change assessment glaciers are widely recognized as key indicators of climate change and their meltwater plays an important role in hydropower production in norway since the last glacier inventory was compiled in northern norway in the 1970s marked fluctuations in glacier length and mass balance have been reported for individual glaciers and the current overall glacier state is thus not well known within the framework of the global land ice measurements from space glims initiative we have created a new inventory for 489 glaciers in the svartisen region northern norway using a landsat enhanced thematic mapper plus etm satellite scene from 7 september 1999 and automated multispectral glacier mapping thresholded band ratios in addition visual inspection and correction of the generated glacier outlines has been applied adverse snow conditions and uncertain drainage divides made glacier mapping challenging in some regions of the study site glacier outlines from 1968 as digitized from a topographic map were used for a quantitative change assessment for a selection of 300 glaciers the overall area change of this sample from 1968 to 1999 was close to zero but with a strongly increasing scatter towards smaller glaciers large area gains 50 for small glaciers 1 km 2 and an unexpected stronger relative area loss towards the wetter coast the overall size changes are small 1 for the three largest ice masses in the study region vestisen ostisen and blamannsisen

retreat rates of debris covered and debris free glaciers in the koshi river basin central himalayas from 1975 to 2010 debris covered glaciers are common in the himalayas and play a key role in understanding future regional water availability and management previous studies of regional glacial changes have often neglected debris covered glaciers or have mixed them with debris free glaciers in this study we generated a new glacier data set that includes debris covered and debris free glaciers to study the glacial surface area change in the koshi river basin in the central himalayas long time series landsat data were used to extract the glacier boundaries using automatic and manual classification methods the glacial area decreased by 10 4 from 1975 to 2010 at a rate of 0 30 a 1 with accelerated melting since 2000 0 47 a 1 small glaciers melted faster than large glaciers in terms of distinctive glacier types debris free glaciers shrank at a rate of 0 45 a 1 faster than debris covered glaciers 0 18 a 1 while debris covered glaciers larger than 5 0 km2 retreated at a rate faster than debris free glaciers of the same sized group we also studied the potential interactions between 222 supraglacial lakes and debris covered glaciers debris covered glaciers with glacial lakes melt faster than glaciers without lakes this study can improve our understanding of the differences in the changes between debris covered and debris free glaciers in the central himalayas and help evaluate water resource changes in the himalayas

the new remote sensing derived swiss glacier inventory ii first results complete swiss glacier inventories are available for 1850 reconstructed and 1973 from aerial photography connected to the global land ice measurements from space project a new swiss glacier inventory for approximately the year 2000 sgi 2000 is compiled mainly based on satellite imagery the developed and applied remotesensing and geographical information system gis methods are described in part i of the contribution in part ii the inventory design first result analyses and comparisons with former glacial conditions are presented as basic entries sgi 2000 contains the individual glacier identification planimetric glacier boundaries as derived from image analysis digitized central flowlines and polygonal glacier basin maps all other parameters are automatically deduced from the above entries and a digital elevation model within a gis here we analyze a set of small bernese and valais glaciers of area 2 these glaciers lost about 21 of area from 1973 to 1998 in addition to about 80 during 1850 1973 both with respect to the 1973 area in order to track the latest trend in more detail anintermediate glacier condition has been compiled from satellite imagery of 1985 this analysis gave an increasing speed of area loss 19 for 1985 98

glacier change 1958 1998 in the north cascades national park complex washington usa the spatial characteristics for all glaciers in the north cascades national park complex usa were estimated in 1958 and again in 1998 the total glacier area in 1958 was 117 3 1 1 km 2 by 1998 the glacier area had decreased to 109 1 1 1 km 2 a reduction of 8 2 0 1 km 2 7 estimated volume loss during the 40 year period was 0 8 0 1 km 3 of ice this volume loss contributes up to 6 of the august september stream flow and equals 16 of the august september precipitation no significant correlations were found between magnitude of glacier shrinkage and topographic characteristics of elevation aspect or slope however the smaller glaciers lost proportionally more area than the larger glaciers and had a greater variability in fractional change than larger glaciers most of the well studied alpine glaciers are much larger than the population median so global estimates of glacier shrinkage based on these well studied glaciers probably underestimate the true magnitude of regional glacier change

melting history of antarctica during the past 60 000 years marked changes in the surface water hydrology of the southern ocean during the past 60 kyr are revealed by a detailed comparison of the oxygen isotopic composition of planktonic and benthic foraminifera from sediment cores and the surface water temperature estimated by a transfer function derived from the distribution of diatoms in the same sediments from 35 to 17 kyr bp the southern ocean polar front was covered by a melt water lid containing a significant contribution from melting icebergs calved from antarctic ice shelves these icebergs may have originated from a succession of surges of the ice shelves

glacier change on axel heiberg island nunavut canada historical records are valuable for assessing glacier change in the canadian high arctic ommanney s 1969 detailed inventory of axel heiberg island glaciers based on photography from 1958 59 has been revisited converted into digital format and compared to glacier extents mapped from 1999 2000 satellite imagery our results show that the island wide ice coverage decreased by 15 92 km 2 in the 42 year period a loss of 2 if the contributions to ice advance of only three surging glaciers are removed then the island wide ice loss approaches 60 km 2 furthermore it is notable that 90 of ice masses smaller than 0 2 km 2 disappeared entirely during the 42 year study period an observation confirmed by field studies successful predictions from the original inventory are highlighted and the likely mechanisms driving the observed advances and retreats are discussed

cryptic trace element variation as an indicator of reverse zoning in a granitic pluton the ricany granite czech republic cryptic variation recognized on the basis of trace element patterns shows the oieany granite in the northeastern part of the hercynian central bohemian pluton to be a reversely zoned high level intrusion unlike many other reversely zoned plutons there are no marked differences in modal composition between the margins and the centre of the intrusion the granite is generally peraluminous and geochemically evolved as demonstrated by its restricted and high sio 2 range and low k rb ratio coupled with a c two fold variation in ba and sr concentrations modelling shows that the geochemical variations can be most readily explained by k feldspar dominated fractionation in a magma chamber below the present level of exposure the reverse zoning is interpreted as the product of emplacement of an essentially single pulse of magma from a deeper level magma chamber in which fractionation has led to a vertical compositional gradient the least evolved magma was emplaced in the centre of the high level pluton with the more evolved magma around it recognition of cryptic reverse zoning in granites has major implications for granite petrogenesis in that the magmatic evolution of such bodies has to be established before assessing potential mechanisms of emplacement

late holocene expansion of eastern larch larix laricina du roi k koch in northwestern quebec the holocene expansion of eastern larch larix laricina du roi k koch at the edge of its geographical range in northwestern quebec was reconstructed using pollen and macrofossils from peat deposits becauselarixis a poor pollen producer the total pollen sum of 300 500 grains per spectrum was supplied by an additional survey of 2000 grains however the use of 2000 pollen counts did not give a betterlarixrecord the combination of both pollen and macrofossil analyses offered greater opportunities to estimate the time of arrival of eastern larch at the edge of its distributional range along the study transect eastern larch established east of 75 w long before 2000 yr b p but not sooner than 5000 yr b p whereas it arrived much later after 1500 yr b p in most sites west of 75 w within a migration corridor around 57 45 n the macrofossil record is completely different between the eastern sites with high frequencies and densities and the western sites where larch occurs sporadically with few remains only concentrated in the upper part of the peat profiles the colonization pattern of eastern larch was patchy in time and space as suggested by the available macrofossil records present distributional pattern in the area and age structure of extant populations the establishment of disjunct larch populations in the westernmost sites most likely proceeded from long distance transport the spatial temporal pattern of eastern larch west of 74 w may have been influenced by the site conditions associated with late deglaciation in central northern quebec

local aspect asymmetry of mountain glaciation a global survey of consistency of favoured directions for glacier numbers and altitudes abstract understanding aspect effects on present day glaciers provides essential background to the palaeoclimatic interpretation of reconstructed former glaciers or glacial cirques several factors influencing glacier mass balance vary with slope aspect these give more glaciers lower glaciers and possibly larger glaciers on favoured aspects their effects can be measured by either vector analysis of the number of glaciers with each aspect or fourier regression of glacier altitude or size against aspect both approaches are applied here to large data sets from the world glacier inventory for all available regions favoured aspect is measured by direction of the resultant vector mean and by the direction of minimum glacier altitude for 51 regions with a total of 66 084 glaciers the two directions are broadly consistent in mid latitudes and in the tropics but large differences occur in the arctic and nepal poleward aspects dominate especially in mid latitudes radiation receipt is the major factor with strong wind effects limited to areas with only moderate relief strength of asymmetry is measured by vector strength from glacier numbers or by a combination of first fourier coefficients from glacier altitudes measuring two different facets of degree of asymmetry they are essentially unrelated the fourier measure is the best estimate of local climatic asymmetry as vector strength is more influenced by topography

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

an extended perfect plasticity method for estimating ice thickness along the flow line of mountain glaciers 1 direct measurement of the thickness of mountain glaciers is difficult over large areas yet knowledge of the thickness is essential for calculating their volumes and future evolution we develop a new method for estimating the ice thickness along glacier flow lines using the perfect plasticity rheological assumption that relates the thickness and surface slope to a yield stress previous studies have used this assumption with the shallow ice approximation to estimate the ice thickness but the standard approach neglects the effect of side drag on glacier stress balance our method addresses this shortcoming and extends the standard method by accounting for the side drag via the glacier width besides the assumed yield stress the inputs for our method are the outline and surface topography of the glacier surface velocity and mass balance data are unnecessary we validated the extended method on five glaciers in northwest china where thickness data are available from radio echo soundings finding that it can reproduce measured thicknesses with a mean absolute error of 11 8 like the standard method moreover for long glacier tongues confined to flow between parallel valley sides this method is found to give more accurate thickness estimates than does the standard method with a mean absolute error of as low as 5 3 sensitivity analysis shows that the estimated ice thickness depends strongly on yield stress and surface slope and less strongly on glacier width because this method is physically more realistic than the standard method and its inputs are easily derivable from remote sensing observations it has the potential to be used for processing large glacier data sets

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

geochemistry of the serifos calc alkaline granodiorite pluton greece constraining the crust and mantle contributions to i type granitoids the late miocene 11 6 9 5 ma granitoid intrusion on the island of serifos western cyclades aegean sea is composed of syn to post tectonic granodiorite with quartz monzodiorite enclaves cut by dacitic and aplitic dikes the granitoid a typical i type metaluminous calcic amphibole bearing calc alkaline pluton intruded the cycladic blueschists during thinning of the aegean plate combining field textural geochemical and new sr nd o isotope data presented in this paper we postulate that the serifos intrusion is a single zoned pluton the central facies has initial 87 sr 86 sr 0 70906 to 0 7106 e nd t 5 9 to 7 5 and 18 qtz 10 to 10 6 whereas the marginal zone or border facies has higher initial 87 sr 86 sr 0 711 to 0 7112 lower e nd t 7 3 to 8 3 and higher 18 qtz 10 6 to 11 9 the small range in initial sr and nd isotopic values throughout the pluton is paired with a remarkable uniformity in trace element patterns despite a large range in silica contents 58 8 to 72 wt sio 2 assimilation of a crustally derived partial melt into the mafic parental magma would progressively add incompatible trace elements and sio2 to the evolving mafic starting liquid but the opposite trend of trace element depletion during magma evolution is observed in the serifos granodiorites thermodynamic modeling of whole rock compositions during simple fractional crystallization fc or assimilation fractional crystallization afc processes of major rock forming minerals at a variety of pressure oxidation state and water activity conditions fails to reproduce simultaneously the major element and trace element variations among the serifos granitoids implying a critical role for minor phases in controlling trace element fractionation both saturation of accessory phases such as allanite and titanite at sio 2 71 wt to satisfy trace element constraints and assimilation of partial melts from a metasedimentary component to match isotopic data must have accompanied fractional crystallization of the major phases

changes in the oceanic 13c 12c ratio during the last 140 000 years high latitude surface water records detailed records of the carbon and oxygen isotopic ratios of neogloboquadrina pachyderma are compared between nine high latitude sediment cores from the northern and southern hemispheres covering the last 140 000 yrs the strong analogies between the 13c records permit to define a 13c stratigraphic scale with three clear cut transitions simultaneous with the oxygen isotopic transitions 65 125 kyrs 54 65 kyrs and 21 13 kyrs the 13c records of n pachyderma in the high latitude cores which follow the changes in 13c of the surface water tco2 near areas of deep water formation present trends similar to the benthic foraminifera 13c records in cores v19 30 and m12 392 although amplitudes of the isotopic shifts are different this implies that a large part of the observed variations represents global changes in the carbon distribution between biosphere and ocean the 13c12c ratios of n pachyderma in the north atlantic cores display larger regional variations at 18 kyrs b p than at present to explain these differences we have plotted the 18 kyrs b p 13c values of n pachyderma from 17 cores distributed n of 40 n comparison with published surface water temperature distribution at 18 kyrs b p indicates that a strong divergent cyclonic cell centered approximatively 55 n and 15 w was active during most of the last ice age maximum this hydrology analogous to the present weddell sea explains the published evidences of bottom water formation if located on the northern flank of the gyre and the strong polar front on the southern flank probable location of intermediate water formation

modelling diverse processes in the petrogenesis of a composite batholith the central bohemian pluton central european hercynides the multiple intrusions making up the central bohemian pluton in the central european hercynides have petrographic and geochemical features consistent with the presence of four main granitoid suites major element trace element and sr nd isotopic compositions are used to model their petrogenesis partial melting of metabasic locks or of a chur like mantle source are interpreted to have produced melts parental to the most primitive calc alkaline sazava suite interaction of basic with more acidic magmas followed by extensive amphibole plagioclase dominated fractionation accounts for the production of trondhjemites alternatively the trondhjemites correspond to small degree melts of a metabasic source afc assimilation fractional crystallization modelling with a paragneiss as a contaminant and increasing d nd values simulates the characteristics of the blatna suite closed system fractionation of strongly enriched mantle derived magmas or their interaction with leucogranitic melts is deduced for the petrogenesis of the shoshonitic certovo bremeno suite partial melting of a metasedimentary source followed by k feldspar dominated fractionation accounts for the granites of rite ricany suite the progression from relatively primitive calc alkaline granitoids towards evolved k rich calc alkaline and shoshonitic rocks is interpreted to reflect the increasing enriched mantle input in the petrogenesis of the later suites the evidence for hercynian subduction is equivocal and the mantle enrichment could have been significantly older

climate at the equilibrium line of glaciers the relationships between temperature precipitation and radiation on glacier equilibrium lines are investigated using 70 glaciers for which the mass balance and meteorological observations have been carried out for sufficiently long periods it is found that the characteristic climate at glacier equilibrium lines can be described using the summer 3 months temperature in a free atmosphere annual total precipitation and the sum of global and long wave net radiation all of these are measured at or very near the equilibrium line altitudes then it is shown how the shift of the equilibriumline will occur as a result of a climatic change finally the effect of the shift of the equilibrium line on the annualmean specific mass balance is analytically derived and compared with observations the present results make it possible to identify the altitudes in climate models where glacierization should begin and to evaluate the mass balance changes as a result of possible future changes in the climate

accessory minerals and the geochemical evolution of crustal magmatic systems a summary and prospectus of experimental approaches it has recently been recognized that accessory minerals in continental rocks may contain a substantial fraction of the whole rock complement of trace elements and geochemically important isotopes this observation is in itself interesting but its importance is magnified many fold when one considers the possible consequences to the geochemical rearrangement that accompanies crustal melting if for example an accessory phase is insoluble in early formed partial melts it may effectively retain in the residue many incompatible elements e g ree and daughter isotopes e g radiogenic pb that would otherwise be partitioned into the melt in addition should an unmelted accessory mineral e g zircon be entrained in a departing melt fraction it may carry with it radiogenic components pb nd143 hf176 characteristic of the source region the effectiveness of phases such as zircon apatite sphene allanite epidote and monazite in the roles noted above can only be gauged from knowledge of the three fundamental accessory phase parameters i e 1 the solubilities of the accessory minerals in crustal melts 2 the equilibrium mineral liquid partition coefficients for the trace element and isotopes of interest and 3 the diffusivities that govern the rates at which equilibrium will be approached in general these parameters can only be measured in laboratory experiments and relatively few data have been accumulated to date it does seem clear however that apatite generally is residual insoluble during crustal melting and zircon can be depending on melting conditions and abundance of zircon in the source petrographic and geochemical studies indicate that monazite allanite and epidote may also be highly insoluble in some cases but the specific circumstances that promote insolubility remain unknown the few experimentally determined partition coefficients now available for apatite and zircon agree qualitatively with natural rock data on mineral separates however preliminary diffusion measurements and inferences from natural systems suggest that trace element and isotopic equilibrium between undissolved accessories and crustal melts is in fact rarely approached ironically it is this very disequilibrium in the form of preserved diffusion profiles that may afford the most information on time temperature histories of melting events continued experimental interest in the fundamental accessory phase parameters will eventually provide the tools that will enable rigorous assessment not only of the timing and duration of crustal melting episodes but also of the extent of melting and re distribution of trace elements and radiogenic isotopes

the new remote sensing derived swiss glacier inventory i methods a new swiss glacier inventory is to be compiled from satellite data for the year 2000 the study presented here describes two major tasks 1 an accuracy assessment of different methods for glacier classification with landsat thematic mapper tm data and a digital elevation model dem 2 the geographical information system gis based methods for automatic extraction of individual glaciers from classified satellite data and the computation of three dimensional glacier parameters such as minimum maximum and median elevation or slope and orientation by fusion with a dem first results obtained by these methods are presented in part ii of this paper kaab and others 2002 thresholding of a ratio image from tm4 and tm5 reveals the best suited glacier map the computation of glacier parameters in a gis environment is efficient and suitable for worldwide application the methods developed contribute to the u s geological survey led global land ice measurements from space glims project which is currently compiling a global inventory of land ice masses within the framework of global glacier monitoring haeberli and others 2000

canada and the world glacier inventory this paper reviews the origins of the world glacier inventory program and canada s participation it tracks the program of the canadian federal government from its initiation to its demise today progress is geared towards the international glims and globglacier programs to which scientists from several canadian universities are making contributions achievements during the past decade towards providing data on canada s glacierized areas in the arctic and in western canada are documented

a new glacier inventory on southern baffin island canada from aster data i applied methods challenges and solutions the quantitative assessment of glacier changes as well as improved modeling of climatechange impacts on glaciers requires digital vector outlines of individual glacier entities unfortunately such a glacier inventory is still lacking in many remote but extensively glacierized regions such as the canadian arctic multispectral satellite data in combination with digital elevation models dems are particularly useful for creating detailed glacier inventory data including topographic information for each entity in this study we extracted glacier outlines and a dem using two adjacent terra aster scenes acquired in august 2000 for a remote region on southern baffin island canada additionally little ice age lia extents were digitized from trimlines and moraines visible on the aster scenes and landsat mss and tm scenes from the years 1975 and 1990 were used to assess changes in glacier length and area because automated delineation of glaciers is based on a band in the shortwave infrared we have developed a new semi automated glacier mapping approach for the mss sensor wrongly classified debris covered glaciers water bodies and attached snowfields were corrected manually for both aster and mss glacier drainage divides were manually digitized by combining visual interpretation with dem information in this first paper we describe the applied methods for glacier mapping and the glaciological challenges encountered e g data voids snow cover ice caps tributaries while the second paper reports the data analyses and the derived changes

oceanographic conditions associated with high abundances of the radiolarian cycladophora davisiana abstract the cosmopolitan radiolarian cycladophora davisiana usually comprises less than 5 of the radiolarian fauna in holocene sediments in recent sediments from the sea of okhotsk however this species frequently represents more than 20 of the radiolarian assemblage at times during the late pleistocene abundances of this species in excess of 40 are recorded in marine sediments from high latitude oceans 40 of both hemispheres the sea of okhotsk apparently represents a modern analogue of climatic and oceanographic conditions that existed throughout large portions of high latitude oceans at times during the late pleistocene the near surface water structure of the sea of okhotsk is characterized by a low salinity surface layer with a strong temperature minimum near its base the low surface salinities are responsible for maintaining near freezing subsurface temperatures as well as establishing relatively stable temperatures and salinities at depths below the temperature minimum this water structure is produced at least in part by intense freezing of sea ice in winter with subsequent summer melting the physical characteristics of the upper water column affect the abundance and activity of shallow dwelling flora and fauna while providing a stable subsurface environment for deeper dwelling fauna

glacier changes in the garhwal himalaya india from 1968 to 2006 based on remote sensing glacier outlines are mapped for the upper bhagirathi and saraswati alaknanda basins of the garhwal himalaya using corona and advanced spaceborne thermal emission and reflection radiometer aster satellite images acquired in 1968 and 2006 respectively a subset of glaciers was also mapped using landsat tm images acquired in 1990 glacier area decreased from 599 9 15 6 km 2 1968 to 572 5 18 0 km 2 2006 a loss of 4 6 2 8 glaciers in the saraswati alaknanda basin and upper bhagirathi basin lost 18 4 9 0 km 2 5 7 2 7 and 9 0 7 7 km 2 3 3 2 8 respectively from 1968 to 2006 garhwal himalayan glacier retreat rates are lower than previously reported more recently 1990 2006 recession rates have increased the number of glaciers in the study region increased from 82 in 1968 to 88 in 2006 due to fragmentation of glaciers smaller glaciers 2 lost 19 4 2 5 0 51 0 07 a 1 of their ice significantly more than for larger glaciers 50 km 2 which lost 2 8 2 7 0 074 0 071 a 1 from 1968 to 2006 the debris covered glacier area increased by 17 8 3 1 0 46 0 08 a 1 in the saraswati alaknanda basin and 11 8 3 0 0 31 0 08 a 1 in the upper bhagirathi basin climate records from mukhim 1900 m a s l and bhojbasa 3780 m a s l meteorological stations were used to analyze climate conditions and trends but the data are too limited to make firm conclusions regarding glacier climate interactions

rare earth element distributions among minerals in a granodiorite and their petrogenetic implications a study of the distribution of lanthanide rare earths in a granodiorite from the eastern peninsular ranges batholith southern california reveals that a large fraction of the ree in this rock resides in the accessory phases sphene and allanite the minerals plagioclase alkali feldspar biotite epidote and apatite each contribute approximately 1 or less of each ree to the whole rock with the exception of eu for which plagioclase contributes 7 sphene and allanite together contain 80 to 95 of each ree each of these phases is zoned in ree concentration with substantial decreases from core to margin textural observations argue for relatively early saturation and precipitation of sphene and allanite in the magma ree zoning trends in sphene and allanite and unexpectedly low ree concentrations in largely later crystallizing minerals such as feldspar indicate that the precipitation of sphene and allanite significantly reduced ree concentrations in residual melts these results illustrate the potential that sphene and allanite have for controlling the behavior of ree in granitic magmas available information collectively suggest that the sampled granodiorite existed as a complete melt that the ree contained in the assemblage of phases were derived by direct crystallization from the melt and that the melt behaved essentially as a closed system once crystallization of the phases now present began close correspondences between the major and trace element chemistries of the granodiorite and phenocryst poor lavas from similar tectonic settings support these conclusions the ree pattern of the granodiorite melt appears to have originated at depth and is characteristic of its source regions and derivation mechanism the high liquidus temperature of a granodiorite melt 1000 c indicates the importance of mantle derived components within the sources of batholithic magmas in the peninsular ranges

magnetic fabric of the řicany granite bohemian massif a record of helical magma flow abstract a highly unusual fabric pattern and inferred flow mechanism was discovered in the shallow level icany granite pluton bohemian massif using an integrated structural and anisotropy of magnetic susceptibility ams study the pluton consists of an outer strongly porphyritic and an inner weakly porphyritic biotite granite separated by a wide gradational contact both varieties share a steep margin parallel magmatic foliation defined by k feldspar phenocrysts and biotite and magnetic ams foliation carried by biotite the steep foliation bears a shallowly plunging magnetic lineation arranged parallel to the circumference of the pluton margin and a steep magnetic lineation in the weakly porphyritic pluton center we propose a new mechanism of magma flow in which the bulk ascent along a steep sided cylindrical conduit was partitioned into a high viscosity phenocryst rich outer margin flowing helically and a low viscosity phenocryst poor center flowing vertically this interpretation is supported quantitatively by a simple model of magma flow within a cylindrical pipe in which the linear decrease in phenocryst content from the pluton margin inwards causes a power law decrease in the effective viscosity of the magma according to the poiseuille equation such a power law viscosity distribution across the conduit produces a central zone of high magma ascent velocity the magnetic ams fabric pattern in the icany pluton may thus preserve a record of helical magma ascent driven by viscosity partitioning in a steep sided conduit which presumably linked an underlying magma chamber with a volcanic feeder at the surface except for one deep seated granite migmatite complex no such helical fabric pattern has been documented in a granite pluton as of yet we propose that the viscosity partitioned helical flow may be a more common magma ascent mechanism in shallow level volcano plutonic systems than previously envisaged

decadal changes in glacier parameters in the cordillera blanca peru derived from remote sensing we present spatial patterns of glacier fluctuations from the cordillera blanca peru glacier area terminus elevations median elevations and hypsography at decadal timescales derived from 1970 aerial photography 2003 spot5 satellite data geographic information systems gis and statistical analyses we derived new glacier outlines from the 2003 spot images and ingested them in the global land and ice measurements from space glims glacier database we examined changes in glacier area on the eastern and western side of the cordillera in relation to topographic and climate variables temperature and precipitation results include 1 an estimated glacierized area of 569 6 21 km 2 in 2003 2 an overall loss in glacierized area of 22 4 from 1970 to 2003 3 an average rise in glacier terminus elevations by 113 m and an average rise in the median elevation of glaciers by 66 m showing a shift of ice to higher elevations especially on the eastern side of the cordillera and 4 an increase in the number of glaciers which indicates disintegration of ice bodies annual air temperature showed a significant upward trend in the last 30 years with larger temperature increases at lower elevations there was a slight but not significant decrease in precipitation our results are consistent with glacier retreat and warming trends noted in the last three decades in the tropics

the second chinese glacier inventory data methods and results the second chinese glacier inventory was compiled based on 218 landsat tm etm scenes acquired mainly during 2006 10 the widely used band ratio segmentation method was applied as the first step in delineating glacier outlines and then intensive manual improvements were performed the shuttle radar topography mission digital elevation model was used to derive altitudinal attributes of glaciers the boundaries of some glaciers measured by real time kinematic differential gps or digitized from high resolution images were used as references to validate the accuracy of the methods used to delineate glaciers which resulted in positioning errors of 10 m for manually improved clean ice outlines and 30 m for manually digitized outlines of debris covered parts the glacier area error of the compiled inventory evaluated using these two positioning accuracies was 3 2 the compiled parts of the new inventory have a total area of 43 087 km 2 in which 1723 glaciers were covered by debris with a total debris covered area of 1494 km 2 the area of uncompiled glaciers from the digitized first chinese glacier inventory is similar to 8753 km 2 mainly distributed in the southeastern tibetan plateau where no images of acceptable quality for glacier outline delineation can be found during 2006 10

a 150 000 year climatic record from antarctic ice during much of the quaternary the earth s climate has undergone drastic changes most notably successive glacial and interglacial episodes the past 150 kyr includes such a climatic cycle the last interglacial the last glacial and the present holocene interglacial a new climatic time series for this period has been obtained using 18 o data from an antarctic ice core

glacier change from the early little ice age to 2005 in the torngat mountains northern labrador canada abstract the glaciers of the torngat mountains of northern labrador are the southernmost of the canadian arctic and the easternmost of continental north america currently 195 small mountain glaciers cover an area in excess of 24 km2 confined mostly to small cirques and upland depressions using a combination of field and remote sensing methods this study reconstructs and dates the areal extent of torngat glaciers at their neoglacial maximums enabling the first assessment of regional glacier change over the past several centuries mapped glacier paleomargins n 165 are compared to current 2005 glaciers and ice masses showing a 52 5 reduction in glacier area with at least 11 former glaciers altogether disappearing glacier change is spatially homogenous and independent of most geographic and topographic factors however glacier elevation and glacier size mitigated total change previously established lichen growth stations were revisited and growth rates recalculated based on 30 year long records enabling the construction of locally derived low and high altitude lichen growth curves using growth rates and in situ lichen measurements the retreat from maximum neoglacial moraine extents are suggested to have occurred between a d 1581 and 1673 these findings indicate a similar magnitude of post lia retreat to mountain glaciers elsewhere yet a much earlier timing 200 years of retreat than other glaciers in the eastern canadian arctic though no definitive answer explaining this discrepancy is presented evidence suggests that regional climate dynamics and the importance of solar radiation for torngat glaciers may play an important role in local glacierization

behavior of trace elements in quartz from plutons of different geochemical signature a case study from the bohemian massif czech republic article i nfo in this study the trace element content in igneous quartz from granitoids of different geochemical types was investigated using the laser ablation icp ms technique the variscan granitoids in the bohemian massif pro vide an excellent opportunity to study the chemical composition of magmatic quartz from the following granite types 1 geochemically primitive i type tonalites and granodiorites 2 peraluminous s type two mica granites 3 moderately fractionated a type volcano plutonic complexes of the teplice caldera and 4 highly fractionated s and a type rare metal granites this diversity of granitoids permitted the study of the chemical composition of magmatic quartz as the result of i different magma protoliths and ii variable degrees of differentiation there were only small differences in the quartz trace element con tents ranging from weakly to moderately differentiated plutons of all geochemical types al mostly in the range between 20 and 250 ppm ti mostly 20 110 ppm b b13 ppm be b0 7 ppm ge b1 ppm li b30 ppm and rb b2 ppm only the s type granites from western erzgebirge contain al enriched quartz mostly 200 400 ppm al since the beginning of its evolution however quartz from the highly fractionated granites group 4 differs significantly this quartz is generally poor in ti b20 ppm ti and enriched in al up to 600 ppm in a type and up to 1000 ppm in s type granites be up to 3 2 ppm ge up to 5 7 ppm li up to 132 ppm particularly in the s type granites and rb up to 15 ppm the contents of the analyzed lithophile elements in the quartz from the highly fractionated granites are similar to the contents reported to be present in evolved complex pegmatites although the input of ti into quartz is controlled mainly by the temperature and pressure of quartz crystallization the entry of al into quartz increases as a function of the water and fluorine content of the residual melt the contents of ge and li increase significantly with the fractionation of parental melt the concentrations of these elements in quartz from highly fractionated granites are controlled by the order of crystallization of the major minerals comb quartz crystallizing before li mica is strongly li enriched whereas groundmass and snowball quartz crystallizing after mica is relatively enriched in ge

tectono climatic influence on landscape changes in the glaciated durung drung basin zanskar himalaya india a geospatial approach abstract this study aims at assessing the tectonic and climatic responses to landscape changes transpired in the durung drung basin in the zanskar himalaya we used relevant geomorphic indices interpreted from aster dem satellite data and supplemented by the field observations to decipher active tectonics and resultant changes in the landscape a n s trending fault in the north of the basin was studied with the help of basin geometry which includes relative parameter length area relation form factor shape factor ratio elongation ratio circulatory ratio compactness coefficient and morphotectonic indices e g drainage basin asymmetry mountain front sinuosity hypsometric integral topographic symmetric factor to comprehend the geomorphic signatures of the active tectonics the geomorphic indices indicate upliftment and tilting of the basin the data on mountain front index and hypsometric integral reveal the uplift and high relief we propose that the western side of the basin is tectonically more active than eastern side suggesting active upliftment the convex nature of hypsometric curve and strongly elongated circulatory ratio reflect competing role of deformation by tectonics the results of mountain front index and hypsometric integral reveal high relief and uplift overall deglaciation of 12 91 was observed in the basin analysis of the meteorological data for the last century 1901 2017 indicate that increase in minimum and maximum temperature coupled with increase in liquid precipitation are probably the main drivers of glacier depletion we conclude that the drainage system of this basin is structurally controlled and overall landscape change is significantly influenced by the ongoing perturbations in the climate system

glaciers dominate eustatic sea level rise in the 21st century ice loss to the sea currently accounts for virtually all of the sea level rise that is not attributable to ocean warming and about 60 of the ice loss is from glaciers and ice caps rather than from the two ice sheets the contribution of these smaller glaciers has accelerated over the past decade in part due to marked thinning and retreat of marine terminating glaciers associated with a dynamic instability that is generally not considered in mass balance and climate modeling this acceleration of glacier melt may cause 0 1 to 0 25 meter of additional sea level rise by 2100