future retreat of great aletsch glacier we model the future evolution of the largest glacier of the european alps great aletsch glacier switzerland during the 21st century for that purpose we use a detailed three dimensional model which combines full stokes ice dynamics and surface mass balance forced with the most recent climate projections ch2018 as well as with climate data of the last decades as a result all ch2018 climate scenarios yield a major glacier retreat results range from a loss of 60 of today s ice volume by 2100 for a moderate co 2 emission scenario rcp2 6 being in line with the paris agreement to an almost complete wastage of the ice for the most extreme emission scenario rcp8 5 our model results also provide evidence that half of the mass loss is already committed under the climate conditions of the last decade

interannual variability of the kuroshio transport in response to the wind stress field over the north pacific its relation to the path variation south of japan we have investigated the interannual variability in the kuroshio transport focusing on the baroclinic response of the upper ocean to the long term variation of the wind stress field over the north pacific from 1961 to 1987 first temporal change of the kuroshio transport at the western boundary from 17 to 31 n has been estimated on the assumptions that the kuroshio is a baroclinic flow confined in the upper layer and that the effect of interior wind stress curl on the volume transport at the western boundary is transferred by nondispersive baroclinic rossby wave peak values in the estimated transport appear in its beginning region 17 21 n when or just before the kuroshio settles into a meandering state south of japan in 1975 1981 and 1986 these peaks are due to negative wind stress curl anomalies which are induced by the intensified trade winds in the central and eastern tropical north pacific on and just after an el nino event and in the western tropical north pacific months to years before the next el nino event such peaks are not found in the barotropic sverdrup transport in downstream regions i e in the east china sea and south of japan north of 23 n on the contrary the estimated transports through baroclinic and barotropic responses do not have such good correlation to the path variation temporal change in thermocline depths estimated from bathythermograph data clearly shows the westward propagations of positive anomalies by nondispersive baroclinic rossby waves at latitudes of the beginning of the kuroshio south of 21 n which is in phase with peaks of the kuroshio baroclinic transport at the western boundary on the other hand there are only the local propagations of the anomalies in the downstream regions as previous studies reported however it is emphasized that temporal change of the geostrophic transport in the east china sea 28 n is coincident with that of the baroclinic transport at the beginning of the kuroshio not with that at the same latitude a numerical experiment with a nonlinear reduced gravity model confirms that temporal changes of the transport in the east china sea and south of japan are due to the advective nonlinear effect of the kuroshio itself while the linear baroclinic response to the wind stress field is dominant in its beginning region

a distributed temperature index ice and snowmelt model including potential direct solar radiation hourly melt and discharge of storglaciaren a small glacier in sweden were computed for two melt seasons applying temperature index methods to a 30 m resolution grid for the melt component the classical degree day method yielded a good simulation of the seasonal patient of discharge but the pronounced melt induced daily discharge cycles were not captured modelled degree day factors calculated for every hour and each gridcell from melt obtained from a distributed energy balance model varied substantially both diurnally and spatially a new distributed temperature index model is suggested attempting to capture both the pronounced diurnal melt cycles and the spatial variations in melt due to the effects of surrounding topography this is accomplished by including a radiation index in terms of potential clear sky direct solar radiation and thus without the need for other data besides air temperature this approach improved considerably the simulation of diurnal discharge fluctuations and yielded a more realistic spatial distribution of melt rates the incorporation of measured global radiation to account for the reduction in direct solar radiation due to cloudiness did not lead to additional improvement in model performance

origin of high potassium talc alkaline i type granitoids many i type granitoid magmas are generated through partial melting of older metaigneous rocks and the compositions of such melts are broadly calc alkaline and metaluminous these melts are granitic to tonalitic and result from thermal extremes in their lower crustal source regions data on the experimental partial melting of common crustal rocks suggest that high k i type granitoid magmas can be derived only from the partial melting of hydrous calc alkaline to high k calc alkaline mafic to intermediate metamorphic rocks in the crust because of their low k2o contents metabasaltic rocks of all kinds are unsuitable as sources and models that propose mixing of mantle derived basaltic magmas and crustal melts are also inadequate there is no requirement that i type calc alkaline magmatism be related in any way to subduction processes

peraluminous i type granites abstract s type granites always contain more al than the amounts of na ca and k in the rock required to form feldspars primarily owing to their derivation from source components that had previously been weathered those rocks are therefore always saturated in al or peraluminous many i type granites are also peraluminous despite i type source rocks typically not being saturated in al it has previously been suggested that this may result from the fractional crystallisation of amphibole however data from compositionally zoned high temperature plutons in the lachlan fold belt show that it is difficult to generate large quantities of peraluminous melt by removal of amphibole most of the i type granites 95 in the lachlan fold belt formed at lower temperatures and almost half of those rocks for which bulk chemical compositions are available are peraluminous among these granites there are 98 separate suites for which there are chemical data for two or more samples with 47 suites that include both metaluminous more mafic and peraluminous more felsic compositions the origin of those peraluminous compositions is fundamental to any understanding of i type granite petrogenesis in this region compositional variations caused by the assimilation or by partial melting of supracrustal rocks are very small as the isotopic variations within these rocks are dominantly between different suites not within suites the partial melting of more mafic source rocks rather than the fractional crystallisation of more mafic magmas is favoured for the origin of these rocks partial melting is the most likely process involved in the petrogenesis of felsic granites where broadly granodioritic monzogranitic batholiths are associated with lesser amounts of tonalite and very minor amounts of mafic rock experimental studies have shown that the melts generated by the partial melting of basaltic to andesitic rocks under crustal conditions are mostly peraluminous during the dehydrational melting of i type granite source rocks at pressures below the garnet stability field biotite and amphibole melt incongruently to yield pyroxenes the excess al is incorporated into the felsic liquid resulting in the generation of peraluminous melts in this instance the excess al in felsic i type granites is a function of the melting process and unrelated to the bulk composition of the source the observed gradation from peraluminous felsic granites to metaluminous compositions in less felsic rocks in largely isotopically closed systems could happen in two ways at higher temperatures of partial melting ca and other components of clinopyroxene could dissolve in the melt with the melt eventually becoming metaluminous alternatively minerals residual from partial melting dominantly pyroxenes and plagioclase could be incorporated in suspension in the melt so that the resulting bulk magma is metaluminous examples of these two extremes and of intermediate cases are well developed among the granites of southeastern australia

la icp ms u pb zircon geochronology geochemistry and kinetics of the wenquan ore bearing granites from west qinling china abstract many hydrothermal cu mo au deposits related to granitoid intrusives were recently discovered in the west qinling orogenic belt wqob these deposits were mainly formed during the late indosinian epoch ca 214 ma and the regional geological setting of cu mo ore formation in wqob during this epoch is poorly understood until now this paper describes the geochronology and geochemistry of the wenquan ore bearing pluton a composite granite body to study the geologic background of magmatic emplacement and ore formation the mo mineralisation occurs at the contact between a fine grained biotite monzogranite and a medium to fine grained porphyritic monzogranite zircon 206pb 238u ages of 223 3 ma biotite monzogranite and 225 3 ma porphyritic monzogranite were obtained geochemical analyses show that the wenquan pluton is a high k calc alkaline to shoshonite series rock with relatively high lree and low hree and a moderate to weak negative eu anomaly relatively negative anomalies of ba ti p nb ta also exist these results imply that the wenquan pluton was emplaced during a transitional process from collision to extension between the yangtze craton and north china craton during the later indosinian epoch the east qinling orogenic belt eqob and wqob had similar tectonic settings and intensive magmatic activity and mo mineralisation occurred the eqob was then involved in the mesozoic subduction of the pacific plate and its subsequent tectonic evolution was different from that of the wqob

a comparison of empirical and physically based glacier surface melt models for long term simulations of glacier response we investigate the performance of five glacier melt models over a multi decadal period in order to assess their ability to model future glacier response the models range from a simple degree day model based solely on air temperature to more sophisticated models including the full shortwave radiation balance in addition to the empirical models the performance of a physically based energy balance eb model is examined the melt models are coupled to an accumulation and a surface evolution model and applied in a distributed manner to rhonegletscher switzerland over the period 1929 2012 at hourly resolution for calibration seasonal mass balance measurements 2006 12 are used decadal ice volume changes for six periods in the years 1929 2012 serve for model validation over the period 2006 12 there are almost no differences in performance between the models except for eb which is less consistent with observations likely due to lack of meteorological in situ data however simulations over the long term 1929 2012 reveal that models which include a separate term for shortwave radiation agree best with the observed ice volume changes indicating that their melt relationships are robust in time and thus suitable for long term modelling in contrast to more empirical approaches that are oversensitive to temperature fluctuations

compositional polarity of triassic granitoids in the qinling orogen china implication for termination of the northernmost paleo tethys abstract the qinling orogen was formed from the closure of the northernmost paleo tethys sea and the tectonic suturing of the yangtze and north china cratons the timing of this collision and the tectonic framework are debated the widely developed triassic granitoids in the western qinling orogen offer a key to understand the tectonic evolution of this region here we compile the geological geochemical and geochronological data of the triassic granitoids from the qingling orogen and conclude that the granitoids north of the mian lue suture were emplaced in an active continental margin related to the northward subduction of the mian lue oceanic plate during 248 200 ma the granitoids can be classified into i and s types with the former constituting the major variety northward from the mian lue fault an s type granite belt appears followed by and locally overlapping with an i type granite belt the i type granite belt can be subdivided into four sub belts from south to north with increasing contents of k2o k2o na2o sio2 th and u and the ratios of k2o na2o rb sr and 87sr 86sr i but decreasing contents of na2o al2o3 mg and ehf t except for the northernmost belt which occurs in the huaxiong block of the north china craton this geochemical polarity of i type granitoids and the zoned distribution of s and i types granitoids cannot be explained through continental collision orogeny including syn to post collision but can be well interpreted by considering the progressive subduction of the northernmost branch of the paleo tethys as represented by the mian lue ocean thus the termination of the northernmost paleo tethys and the onset of the continental collision between the yangtze and the north china plates are considered to have occurred at about 200 ma during the transition from triassic to jurassic our model is also supported by the available data from other studies and provides a revised framework for the timing and tectonics of assembly of the yangtze and the north china cratons

introduction to tectonics of china abstract the continental crust of china is a mosaic of cratonic blocks and orogenic belts containing small cratons and terranes with various tectonic settings they have diverse origins and complex histories of amalgamation and often suffered repeated reworking after multiple episodes of amalgamation in the last three decades extensive geological geochemical and geophysical investigations have been carried out on these cratonic blocks and intervening orogenic belts producing an abundant amount of new data and competing interpretations this provides important insights into understanding the formation and evolution of the chinese continents the papers assembled in this volume present a timely and comprehensive overview on major advancements and controversial issues related to the formation and evolution of continental crust in china complex tectonic histories were experienced not only by the large scale cratonic blocks and orogenic belts but also by small scale terranes and orogens between and inside these blocks nevertheless our understanding of lithotectonic units and geological processes has been greatly advanced by recent studies of zirconology and geochemistry for various rock types from major petrotectonic units in china it has been further advanced from integrated interpretations of geochemical and petrological data for petrogenesis of magmatic rocks an overview of these observations and interpretations provides new insights into understanding the continental plate tectonics and the chemical geodynamics of subduction zones

melts_excel a microsoft excel based melts interface for research and teaching of magma properties and evolution the thermodynamic modeling software melts is a powerful tool for investigating crystallization and melting in natural magmatic systems rhyolite melts is a recalibration of melts that better captures the evolution of silicic magmas in the upper crust the current interface of rhyolite melts while flexible can be somewhat cumbersome for the novice we present a new interface that uses web services consumed by a vba backend in microsoft excel the interface is contained within a macro enabled workbook where the user can insert the model input information and initiate computations that are executed on a central server at ofm research results of simple calculations are shown immediately within the interface itself it is also possible to combine a sequence of calculations into an evolutionary path the user can input starting and ending temperatures and pressures temperature and pressure steps and the prevailing oxidation conditions the program shows partial updates at every step of the computations at the conclusion of the calculations a series of data sheets and diagrams are created in a separate workbook which can be saved independently of the interface additionally the user can specify a grid of temperatures and pressures and calculate a phase diagram showing the conditions at which different phases are present the interface can be used to apply the rhyolite melts geobarometer we demonstrate applications of the interface using an example early erupted bishop tuff composition the interface is simple to use and flexible but it requires an internet connection the interface is distributed for free from http melts ofm research org

interannual variability of the kuroshio onshore intrusion along the east china sea shelf break effect of the kuroshio volume transport the interannual variability of the kuroshio onshore intrusion koi across the east china sea ecs shelf break and its response to the ecs kuroshio volume transport kvt during 1993 approximate to 2010 are studied based on a high resolution real time and global ocean general circulation model since variability of kvt is mainly determined in the interior pacific it is rather a remote than a local factor for the local ecs koi on interannual time scales kvt affects koi not only in the net volume transport across the entire shelf break but also in the spatial pattern along the shelf break when kvt increases the intrusion decreases increases upstream downstream of the major intrusion region northeast of taiwan the retreating increases decreases upstream downstream of the main veering region southwest of kyushu these patterns are caused by cyclonic eddies induced by the seaward deflection of the kuroshio axis from the shelf break which ultimately results from the kvt increase a diagnostic mechanism of koi approximate to msin delta h 1 is proposed where h is the bottom depth is the angle between isobaths and the vertically averaged current and m is the absolute volume transport at the shelf break is large in the major intrusion retreating regions and stable on interannual time scales while m changes with opposite signs between upstream and downstream of the major intrusion retreating regions the mechanism explains well the relation of local kvt and the spatial pattern of koi along the shelf break in both the mean state and the interannual variations

the anatectic effect on the zircon hf isotope composition of migmatites and associated granites zircon hf isotope composition is widely used to trace the growth and evolution of continental crust however it is controversial whether the hf isotope composition of magmatic zircons can faithfully reflect that of their sources especially for s type granites in order to provide an insight into this issue we have revisited the published lu hf isotope data of zircons from well studied migmatites and associated granites in the sulu orogen and the cathaysian terrane respectively the results show greatly elevated 176hf 177hf ratios by more than 10e units for newly grown zircon domains compared to the relict zircon domains this indicates considerable contributions from non zircon hf to anatectic melts during crustal anatexis and subsequent magmatism furthermore this more radiogenic hf isotope signature was not erased during magmatic processes such as crystal fractionation during melt ascent and emplacement the budget of hf isotopes in source rocks with respect to mineral lu hf ratios suggests the involvement of hf bearing major minerals in anatectic reactions by dissolving hf bearing major minerals into the anatectic melts the significant hf isotope variations in some anatectic and magmatic zircon domains from the migmatites and granites suggest not only the source heterogeneity but also the variable non zircon hf contributions as such the hf isotope compositions of anatectic and magmatic zircons are substantially dictated by the mass balance between the non zircon hf from anatectic reactions and the zircon hf from the dissolution of protolith zircons into the anatectic melts they are primarily controlled by p t conditions and mechanism of crustal anatexis and the magmatic processes during melt evolution the present study highlights the important contribution of non zircon hf to the anatectic and magmatic zircon domains in this regard the greatly elevated 176hf 177hf ratios for newly grown zircon domains in the migmatites and granites cannot reflect the hf isotope compositions of their source rocks such a deviation must be kept in mind when linking relatively depleted hf isotope compositions to the nature of source rocks in petrogenetic interpretation and to the growth of continental crust the contribution of non zircon hf can also better account for the variable hf isotope compositions often shown by zircons from s type granites

water contents of silicic to intermediate magmas silicic to intermediate magmas have water contents that range from 1 wt to around 7 wt depending on the character and depth of the magma source type of melting reaction and the degree of differentiation the condition of water saturation is rare implying that crustal magma genesis generally takes place under fluid absent conditions or that any fluid present must contain volatile species other than h2o the source and quantity of water present during partial melting profoundly affect the types of melting reactions residues and magmas as well as subsequent magma evolution for s type granitic magmas melting reactions involving muscovite breakdown in pelites yield low temperature wet melts that form veins pockets and small plutons in regional metamorphic terranes biotite breakdown in pelites near the amphibolite granulite facies transition yields hotter magmas with variable water contents these are emplaced at medium to high levels under granulite facies conditions biotite breakdown in quartzofeld spathic rocks yields high temperature dry magmas emplaced as subvolcanic batholiths and volcanics

global glacier mass changes and their contributions to sea level rise from 1961 to 2016 glaciers distinct from the greenland and antarctic ice sheets cover an area of approximately 706 000 square kilometres globally1 with an estimated total volume of 170 000 cubic kilometres or 0 4 metres of potential sea level rise equivalent2 retreating and thinning glaciers are icons of climate change3 and affect regional runoff4 as well as global sea level5 6 in past reports from the intergovernmental panel on climate change estimates of changes in glacier mass were based on the multiplication of averaged or interpolated results from available observations of a few hundred glaciers by defined regional glacier areas7 10 for data scarce regions these results had to be complemented with estimates based on satellite altimetry and gravimetry11 these past approaches were challenged by the small number and heterogeneous spatiotemporal distribution of in situ measurement series and their often unknown ability to represent their respective mountain ranges as well as by the spatial limitations of satellite altimetry for which only point data are available and gravimetry with its coarse resolution here we use an extrapolation of glaciological and geodetic observations to show that glaciers contributed 27 22 millimetres to global mean sea level rise from 1961 to 2016 regional specific mass change rates for 2006 2016 range from 0 1 metres to 1 2 metres of water equivalent per year resulting in a global sea level contribution of 335 144 gigatonnes or 0 92 0 39 millimetres per year although statistical uncertainty ranges overlap our conclusions suggest that glacier mass loss may be larger than previously reported11 the present glacier mass loss is equivalent to the sea level contribution of the greenland ice sheet12 clearly exceeds the loss from the antarctic ice sheet13 and accounts for 25 to 30 per cent of the total observed sea level rise14 present mass loss rates indicate that glaciers could almost disappear in some mountain ranges in this century while heavily glacierized regions will continue to contribute to sea level rise beyond 2100 the largest collection so far of glaciological and geodetic observations suggests that glaciers contributed about 27 millimetres to sea level rise from 1961 to 2016 at rates of ice loss that could see the disappearance of many glaciers this century

u pb zircon dating geochemical and sr nd hf isotopic compositions of early indosinian intrusive rocks in west qinling central china petrogenesis and tectonic implications the qinling dabie sulu orogenic belt is the junction between the north and south china blocks which resulted from the final amalgamation of china continents during the indosinian indosinian granitoids are widespread in the qinling orogen and their geneses can thus constrain the evolution of china continent we carried out a combined u pb zircon dating and geochemical study for the shuangpengxi granodiorite pluton and the xiekeng diorite granodiorite pluton in the middle part of the west qinling orogen u pb zircon dating shows that the magma crystallization ages of 242 3 ma for the shuangpengxi pluton and 244 242 ma for the xiekeng pluton geochemical and sr nd hf isotopic compositions reveal that the magma of the shuangpengxi granodiorite was derived from partial melting of crustal materials the xiekeng diorites can be divided into high al diorite and high mg diorite both of them resulted from partial melting of enriched lithospheric mantle but their mantle source had been modified by previous slab derived melt the high al diorite was formed by fractional crystallization of olivine pyroxene and or preferential accumulation of plagioclase and the high mg diorite was formed by fractional crystallization of olivine and or preferential accumulation of pyroxene the xiekeng granodioritic porphyry was formed by mixing of crust derived and mantle derived melts we propose that the early indosinian magmatism resulted from break off of subducted oceanic slab after collision the slab break off model can well explain the linear distribution of the early indosinian plutons and rapid crustal uplift during the middle triassic in the west qinling

on the meridional surface profile of the gulf stream at 55 w nine month records from nine inverted echo sounders iess are analyzed to describe the mean baroclinic gulf stream at 55 w ies acoustic travel times are converted to thermocline depth which is optimally interpolated kinematic and dynamic parameters gulf stream meridional position velocity and vorticity are calculated primary gulf stream variability is attributed to meandering and changes in direction a mean stream coordinate relative to gulf stream instantaneous position and direction meridional profile is derived and compared with results presented by other investigators the mean velocity is estimated at 0 84 m s 1 directed 14 to the right of eastward and the thermocline 12 c drops 657 m north to south corresponding to a baroclinic rise of the surface of 0 87 m the effect of gulf stream curvature on temporal mean profiles is found to be unimportant and of minimal importance overall the derived downstream current profile is well represented by a gaussian function and is about 190 km wide where it crosses zero surface baroclinic transport is estimated to be 8 5 104 m2 s 1 and maximum shear flanking the maximum is 1 2 10 5 s 1 results compare well with other in situ observational results from the same time period on the other hand analyses by others of concurrent satellite altimetry geosat suggest a considerably narrower more intense mean gulf stream

the compositional variation of i type granites constraints from geochemical analyses and phase equilibrium calculations for granites from the qinling orogen central china abstract there is a large compositional variation of i type granites although partial melting and fractional crystallization are the two primary mechanisms for the variation it is intriguing to know how they jointly work this issue is addressed by a combined study of geochemistry and phase equilibrium modelling for a triassic pluton from the qinling orogen the pluton consists of high k calc alkaline i type granites geochemical results suggest that the granites are likely sourced from triassic mafic intermediate igneous rocks compared with experimental melts it is inferred that the natural granites are not the crystallized product from pure magmatic melts this is confirmed by phase equilibrium calculations that have utilized the triassic mafic intermediate igneous rocks as the source yielding modelled melts that contain too low feot mgo and mg to match the target granites the addition of restitic mineral assemblages to melts can relieve the discrepancy but the modelled magmas have much higher cao than the granites replacing equilibrium melting by disequilibrium melting in terms of the plagioclase behavior can lead to a satisfactory match furthermore by taking the average of the target granites as a parental magma the modelled crystalline products can well reproduce the variation trends in the high k calc alkaline i type granites from the qinling orogen in this regard the crustal anatexis would produce the parental magma at first which experienced fractional crystallization to form the granitic pluton with the compositional variation as observed therefore these two processes would jointly lead to the compositional variation of i type granites in nature

contemporary glacier retreat triggers a rapid landslide response great aletsch glacier switzerland the destabilization and catastrophic failure of landslides triggered by retreating glaciers is an expected outcome of global climate change and poses a significant threat to inhabitants of glaciated mountain valleys around the globe of particular importance are the formation of landslide dammed lakes outburst floods and related sediment entrainment based on field observations and remote sensing of a deep seated landslide located at the present day terminus of the great aletsch glacier we show that the spatiotemporal response of the landslide to glacier retreat is rapid occurring within a decade our observations uniquely capture the critical period of increase in slope deformations onset of failure and show that measured displacements at the crown and toe regions of the landslide demonstrate a feedback mechanism between glacier ice reduction and response of the entire landslide body these observations shed new light on the geomorphological processes of landslide response in paraglacial environments which were previously understood to occur over significantly longer time periods

a new algorithm to simulate the dynamics of a glacier theory and applications we propose a novel eulerian algorithm to compute the changes of a glacier geometry for given mass balances the surface of a glacier is obtained by solving a transport equation for the volume of fluid vof the surface mass balance is taken into account by adding an interfacial term in the transport equation an unstructured mesh with standard stabilized finite elements is used to solve the non linear stokes problem the vof function is computed on a structured grid with a high resolution the algorithm is stable for courant numbers larger than unity and conserves mass to a high accuracy to demonstrate the potential of the algorithm we apply it to reconstructed late glacial states of a small valley glacier vadret muragl in the swiss alps

tectonics of the qinling central china tectonostratigraphy geochronology and deformation history abstract the qinling orogen preserves a record of late mid proterozoic to cenozoic tectonism in central china high pressure metamorphism and ophiolite emplacement songshugou ophiolite assembled the yangtze craton including the lower qinling unit into rodinia during the 1 0 ga grenvillian orogeny the lower qinling unit then rifted from the yangtze craton at 0 7 ga subsequent intra oceanic arc formation at 470 490 ma was followed by accretion of the lower qinling unit first to the intra oceanic arc and then to the sino korea craton subduction then imprinted a 400 ma andean type magmatic arc onto all units north of the northern liuling unit oblique subduction created silurian devonian wnw trending sinistral transpressive wrench zones e g lo nan shang dan and late permian early triassic subduction reactivated them in dextral transpression lo nan shang xiang shang dan and subducted the northern edge of the yangtze craton exhumation of the cratonal edge formed the wudang metamorphic core complex during dominantly pure shear crustal extension at 230 235 ma post collisional south directed shortening continued through the early jurassic cretaceous reactivation of the qinling orogen started with nw se sinistral transtension coeval with large scale early cretaceous crustal extension and sinistral transtension in the northern dabie shan it presumably resulted from the combined effects of the siberia mongolia sino korean and lhasa west burma qiangtang indochina collisions and pacific subduction regional dextral wrenching was active within a ne sw extensional regime between 60 and 100 ma an early cretaceous andean type continental magmatic arc with widespread early cretaceous magmatism and back arc extension was overprinted by shortening related to the collision of yangtze indochina block with the west philippines block strike slip and normal faults associated with eocene half graben basins record paleogene nne ssw contraction and wnw ese extension the neogene is characterized by normal faults and nne trending sub horizontal extension pleistocene quaternary nw se extension and ne sw contraction comprises sinistral strike slip faults and is part of the nw se extension imposed across eastern asia by the india asia collision

modelling the retreat of grosser aletschgletscher switzerland in a changing climate for more than a century alpine glaciers have been retreating dramatically and they are expected to shrink even more quickly over the coming decades this study addresses the future evolution of grosser aletschgletscher switzerland the largest glacier in the european alps a three dimensional combined surface mass balance and glacier dynamics model was applied the ice flow was described with the full stokes equations the glacier surface evolution was obtained by solving a transport equation for the volume of fluid daily surface melt and accumulation were calculated on the basis of climate data the combined model was validated against several types of measurements made throughout the 20th century for future climate change scenarios based on regional climate models in the ensembles project were used according to the median climatic evolution aletschgletscher was expected to lose 90 of its ice volume by the end of 2100 even when the model was driven using current climate conditions the past two decades the glacier tongue experienced a considerable retreat of 6 km indicating its strong disequilibrium with the present climate by including a model for the evolution of supraglacial debris and its effect in reducing glacier melt we show that this factor can significantly slow future glacier retreat

zircon u pb ages and geochemistry of the wenquan mo bearing granitioids in west qinling china constraints on the geodynamic setting for the newly discovered wenquan mo deposit abstract east qinling is the largest porphyry molybdenum province in the world these mo deposits have been well documented in west qinling however few mo deposits have been discovered although granitic rocks are widespread recently the wenquan porphyry mo deposit has been discovered in gansu province which provides an insight into mo mineralization in west qinling in this paper we report pb isotope compositions for k feldspar and sulfides s isotope ratios for sulfides the results obtained from petrochemical study and from in situ la icp ms zircon u pb dating and hf isotopes the granitoids are enriched in lile and lree with ree and trace element patterns similar to continental crust suggesting a crustal origin the mg 40 05 to 56 34 and cr and ni contents are high indicating a source of refractory mafic lower crust the e hf t values of zircon grains from porphyritic monzogranite range from 2 9 to 0 6 and from granitic porphyry vary from 3 3 to 1 9 the zircons have t dm2 of 1014 to 1196 ma for the porphyritic monzogranite and 954 to 1224 ma for the granitic porphyry implying that these granitoids were likely derived from partial melting of a late mesoproterozoic juvenile lower crust the pb isotope compositions of the granitoids are similar to granites in south china showing that the magma was sourced from the middle lower crust in the southern qinling tectonic unit the pb isotopic contrast between the mo bearing granitoids and ores shows that the pb in the ore forming solution was derived from fractionation of a triassic magmatic system 34 s values of sulfides are between 5 02 and 5 66 similar to those associated with magmatic hydrothermal systems la icp ms zircon u pb dating yields crystallization ages of 216 2 1 7 and 217 2 2 0 ma for the granitoids consistent with a previously reported molybdenite re os isochron age of 214 4 7 1 ma this suggests that the mo mineralization is related to the late triassic magmatism in the west qinling orogenic belt in view of these geochemical results and known regional geology we propose that both granitoid emplacement and mo mineralization in the wenquan deposit resulted from the triassic collision between the south qinling and the south china block along the mianlue suture since triassic granitoid plutons commonly occur along the qinling orogenic belt the triassic wenquan mo bearing granitoids highlight the importance of the triassic tectono magmatic belt for mo exploration in order to apply this metallogenic model to the whole qinling orogen further study is needed to compare the wenquan deposit with other deposits

geologic framework and tectonic evolution of the qinling orogen central china abstract the geologic framework of the qinling orogen was built up through interplay of three blocks the north china block including the north qinling the south qinling and the south china block separated by the shangdan and mianlue sutures the shangdan suture resulted from middle paleozoic collision of the north china block and the south qinling the mianlue suture resulted from late triassic collision of the south qinling and the south china block present upper crust of the qinling is structured dominantly by thrust fold systems the north qinling displays thick skinned deformation with crystalline basement involved whilst the south qinling is characterized by thin skinned thrusts and folds detached above the lower sinian two types of precambrian basement crystalline and transitional are defined according to lithology and metamorphic grade and different in age stratigraphic and sedimentary architecture is characterized by distinct zonation the qinling orogen experienced a prolonged continental divergence and convergence between blocks during the period from late neoproterozoic to early paleozoic times the south qinling was the northern margin of the south china block and the north qinling was the southern margin of the north china block separated by a proto tethyan qinling ocean the north qinling evolved into an active margin when the proto tethyan qinling ocean subducted northward during ordovician time collision of the south and north qinling took place in middle paleozoic along the shangdan suture synchronous with the collision rifting occurred at the southern rim of the south qinling and was followed by the opening of the paleo tethyan qinling ocean during the late paleozoic resulting in the splitting of the south china block from the south qinling collision of the south qinling and the south china block came about in the late triassic along the mianlue suture the late triassic collisional orogeny caused extensive fold and thrust deformation and granitoid intrusions throughout the qinling and led to final amalgamation of the north and south china blocks

multi stage granitic magmatism during exhumation of subducted continental lithosphere evidence from the wulong pluton south qinling abstract detailed petrology and zircon u pb dating data indicate that the wulong pluton is a zoned granitic intrusive formed from successive increments of magmas an age range of at least 30 ma is recorded from the 225 235 ma quartz diorite on the pluton margin the ca 218 ma granodiorite in the intermediate zone and the ca 207 ma monzogranite at the pluton center all the granitoids display evolved sr nd pb isotopic compositions with 87 sr 86 sr i of 0 7044 0 7062 unradiogenic nd e nd t values of 6 1 to 3 0 nd model ages of 1 1 1 3 ga and moderately radiogenic pb compositions 206 pb 204 pb i 17 500 17 872 207 pb 204 pb i 15 513 15 549 208 pb 204 pb i 37 743 38 001 in combination with variations in zircon hf isotopic compositions with e hf t values in each stage span 12 units and the hf isotopic model ages of 800 1600 ma these features suggest that the granitoids might have been derived from the reworking of an old lower crust mixed with paleozoic and proterozoic materials the rocks also display an adakitic affinity with sr 479 973 ppm high sr y ratios mostly 60 and negligible eu anomalies eu eu 0 78 0 97 but low rb sr ratios low y 4 6 17 ppm hree yb 0 95 1 7 ppm yb lu 6 7 and dy yb 1 9 2 4 ratios suggesting the absence of plagioclase and presence of garnet amphibole in their residue considering a large gap among their crystallization ages we propose that the geochemical evolution from pluton margin to center was controlled mainly by melting conditions and source compositions rather than fractional crystallization mafic enclaves that were hosted in the quartz diorite and granodiorite are mainly syenogabbroic to syenodioritic in composition and are metaluminous and enriched in lree and liles but are depleted in hfse and display an evolved sr nd pb isotopic composition suggesting that they may have been derived from the partial melting of an enriched mantle lithosphere which was metasomatized by adakitic melts and fluids from a subducted continental crust in combination with the results of the triassic ultra high pressure metamorphic rocks in the dabie orogenic belt we apply a model involving the exhumation of subducted continental crust to explain the formation of the wulong pluton at the first stage a dense and refractory mafic lower crust that was trapped at mantle depth by continental subduction witnessed melting under high temperature conditions to produce the quartz diorite magma characterized by low sio 2 60 65 63 98 wt and high tio 2 0 39 0 86 wt the magma subsequently interacted with mantle peridotite leading to high mg 57 67 and the metasomatism of the overriding mantle wedge at the second stage an asthenosphere upwelling that was probably caused by slab break off at ca 220 ma melted the enriched sub continental lithospheric mantle sclm to produce mafic magmas represented by the mafic enclaves that are hosted in the quartz and granodiorite resulting in the partial melting of the shallower subducted crust and generating the granodiorite that is distinguished by high sio 2 69 16 70 82 wt high al 2 o 3 15 33 16 22 wt and a cnk values mostly 1 05 at the third stage the final collapse of the triassic qinling dabie orogenic belt at ca 215 205 ma caused extensive partial melting of the thickened orogenic lower crust to produce the monzogranite which is characterized by high sio 2 67 68 70 29 wt low tio 2 mostly

interannual variability of the kuroshio frontal structure along its western boundary in the north pacific ocean associated with the 1982 enso event abstract the vertically averaged temperature tav over the upper 200 m of ocean in the western boundary of the north pacific is used to detect changes in the strength and path of the kuroshio front along the western boundary from luzon 18 n to honshu 34 n during the period 1979 82 during this time the kuroshio front experienced significant interannual changes associated both with the disappearance of the kuroshio meander in late 1980 and with the development of the 1982 enso event in early 1982 when the kuroshio meander south of honshu disappeared from the fall of 1980 until the summer of 1981 the intensity of the kuroshio front increased associated with warmer than normal temperatures all along the western boundary of the north pacific from luzon to honshu the amplitude of the kuroshio meander was also correlated with fluctuations in the path of the kuroshio front at the tokara strait 30 n and the bashi strait 20 n and with the amplitude of the east china sea meander the east china sea me

monitoring and analysis of active rockslide glacier interactions moosfluh switzerland abstract valley glaciers have traditionally been expected to significantly influence the stability and movement rates of adjacent paraglacial landslides however detailed studies related to the mechanical and displacement interactions between glacier ice and unstable rock slopes are very rare here we present a detailed in situ investigation of the spatial variations of the displacement field of the great aletsch glacier in the surroundings of a large active instability i e the moosfluh landslide a deep seated gravitational slope deformation with superimposed large 1 5 million m3 secondary rockslides formed during fall 2016 we performed repeat uav based photogrammetric surveys during 3 days 74 h and applied digital image correlation techniques to record high resolution surface displacement vector fields of the landslide stable slopes and adjacent glacier our results show that the secondary rockslide adjacent to the glacier is composed of two parts of 1 5 and 2 8 million m3 volume respectively showing significant differences in mean displacement velocities 0 4 and 0 9 m in 74 h respectively excluding rapid movements from detached blocks both rockslide compartments induce clear deflections of the glacier flow field moving with a maximum velocity of about 0 3 to 0 4 m in 74 h this influence is highest near the ice contact boundary and decreases within a distance of about 100 200 m from the rock slope instability we investigate the viscous forces at the landslide glacier contact using a straightforward analytical model for an incompressible rockslide block sliding along a planar cohesionless surface into ice these forces are then applied to a slope stability model based on the limit equilibrium concept representing the real geometry at the interface boundary to quantitatively explore the true buttressing effects of valley glaciers on an already moving slope instability we show that the viscous ice deformation plays an important role in mediating the displacement velocities of landslides in unstable conditions while on the other hand the slope support from the valley glacier has very little influence on the stability of the investigated rockslides as most valley glaciers are currently strongly retreating due to global warming uncovering significant numbers of pre lia slope instabilities this detailed investigation provides important hints on their potential displacement behavior understanding the factors controlling landslide velocity is of great importance for hazard analyses and early warning hence this study has implications beyond academic interest e g for the planning and operation of alpine infrastructure such as cable cars or hydropower systems

ice volume changes of selected glaciers in the swiss alps since the end of the 19th century the evolution of surface topography of glaciers in the swiss alps is well documented with high resolution aerial photographs repeatedly recorded since the 1960s and further back in time with topographic maps including elevation contour lines first surveyed in the mid 19th century in order to quantify and interpret glacier changes in the swiss alps time series of volume changes over the last 100 150 years have been collected the available datasets provide a detailed spatial resolution for the retreat period since the end of the little ice age the spatial distribution as well as temporal variations of the thickness change were analyzed a significant ice loss since the end of the 19th century was observed in the ablation area while the changes in the accumulation area were small we found moderate negative secular rates until the 1960s followed by steady to positive rates for about two decades and strong ice loss starting in the 1980s which has lasted until the present an evaluation of 19 glaciers revealed a total ice volume loss of about 13 km 3 since the 1870s of which 8 7 km 3 occurred since the 1920s and 3 5 km 3 since 1980 decadal mean net balance rates for the periods 1920 60 1960 80 and 1980 present are 0 29 0 03 and 0 53 m a 1 w e respectively

on the imbalance and response time of glaciers in the european alps glaciers in the european alps rapidly lose mass to adapt to changes in climate conditions here we investigate the relationship and lag between climate forcing and geometric glacier response with a regional glacier evolution model accounting for ice dynamics the volume loss occurring as a result of the glacier climate imbalance increased over the early 21st century from about 35 in 2001 to 44 in 2010 this committed loss reduced to 40 by 2018 indicating that temperature increase was outweighing glacier retreat in the early 2000s but that the fast retreat effectively somewhat diminished glacier imbalances we analyze the lag in glacier response for each individual glacier and find mean response times of 50 28 years our findings indicate that the response time is primarily controlled by glacier slope and secondarily by elevation range and mass balance gradient rather than by glacier size