understanding the interrelationships among mass balance meteorology discharge and surface velocity on chhota shigri glacier over 2002 2019 using in situ measurements

manifestations and mechanisms of the karakoram glacier anomaly global scale glacier shrinkage is one of the most prominent signs of ongoing climatic change however important differences in glacier response exist at the regional scale and evidence has accumulated that one particular region stands out the karakoram in the past two decades the region has shown balanced to slightly positive glacier budgets an increase in glacier ice flow speeds stable to partially advancing glacier termini and widespread glacier surge activity this is in stark contrast to the rest of high mountain asia where glacier retreat and slowdown dominate and glacier surging is largely absent termed the karakoram anomaly recent observations show that the anomalous glacier behaviour partially extends to the nearby western kun lun and pamir several complementary explanations have now been presented for the anomaly s deeper causes but our understanding is far from complete whether the anomaly will continue to exist in the coming decades remains unclear but its long term persistence seems unlikely in light of the considerable warming anticipated by current projections of future climate glaciers in the karakoram region with their balanced or slightly positive mass balance stand out from global glacier shrinkage but this anomaly is not expected to persist in the long term according to an overview of the possible explanations

examining geodetic glacier mass balance in the eastern pamir transition zone glaciers in the eastern pamir have reportedly been gaining mass during recent decades even though glaciers in most other regions in high mountain asia have been in recession questions still remain about whether the trend is strengthening or weakening and how far the positive balances extend into the eastern pamir to address these gaps we use three different digital elevation models to reconstruct glacier surface elevation changes over two periods 2000 09 and 2000 15 16 we characterize the eastern pamir as a zone of transition from positive to negative mass balance with the boundary lying at the northern end of kongur tagh and find that glaciers situated at higher elevations are those with the most positive balances most 67 of 55 glaciers displayed a net mass gain since the 21st century this led to an increasing regional geodetic glacier mass balance from 0 06 0 16 m w e a 1 in 2000 09 to 0 06 0 04 m w e a 1 in 2000 15 16 surge type glaciers which are prevalent in the eastern pamir showed fluctuations in mass balance on an individual scale during and after surges but no statistical difference compared to non surge type glaciers when aggregated across the region

sea level reconstruction for turonian sediments from tanzania based on integration of sedimentology microfacies geochemistry and micropaleontology abstract despite many advances in sea level research the nature of cyclic eustatic sea level fluctuations during warm periods without or with much reduced polar ice remains enigmatic recently published 18 o records from extremely well preserved turonian microfossils from tanzania do not support the contentious idea of glacio eustatic control of global sea level changes during the warmest period of the cretaceous for the same locality site tdp 31 we reconstruct relative sea level changes based on sequence stratigraphy and integration of sedimentology microfacies geochemistry and micropaleontology four local sequence boundaries sbs tutz1 4 are recognized at the base middle and top of the helvetoglobotruncana helvetica zone and in the late turonian the lowstands are characterized by increased grain size enhanced organic carbon flux faunal assemblage changes and bulk 13 c org and foraminiferal 13 c f and 18 o f minima strong benthic and planktic foraminiferal turnovers above the top middle turonian sb tutz3 probably reflect shallowing from upper slope to outer shelf and or eutrophication the tdp 31 age model is refined through inter regional comparison of planktic foraminiferal ranges and 13 c records from three other south tethyan localities odp holes 762c and 763b exmouth plateau and the guru section tibet this age model enables correlation of the regressive events at a global scale and suggests that within stratigraphic uncertainty the tdp 31 depositional sequences are synchronous with the global turonian third order sequences and are likely driven by eustasy these correlations together with recent astrochronological and radiometric dating indicate a considerably younger age 91 17 0 52 ma for the top h helvetica zone than currently assumed resulting in zonal duration of 2 35 0 52 myr foraminiferal stable isotope data from tdp 31 indicate slight surface and bottom water warming during the regressions and possibly a minor surface water salinity decrease which is inconsistent with glacio eustatic forcing of turonian third order sea level cycles and is more in line with the model of aquifer eustasy

slight glacier mass loss in the karakoram region during the 1970s to 2000 revealed by kh 9 images and srtm dem an anomalously slight glacier mass gain during 2000 to the 2010s has recently been reported in the karakoram region however to date no investigations of the region wide glacier mass balance in the karakoram prior to 2000 have been reported leaving a knowledge gap for assessing glacier responses to climate change we calculated elevation and mass change using dems generated from kh 9 images acquired during 1973 1980 and the 1 arc second srtm dem we find a slight mass loss of 0 09 0 03 m w e a 1 12 366 km2 for 1973 2000 which is less negative than the global average rate for 1971 2009 0 31 0 19 m w e a 1 within the karakoram the glacier change patterns are spatially and temporally heterogeneous in particular a nearly stable state in the central karakoram 0 04 0 05 m w e a 1 during the period 1974 2000 implies that the karakoram anomaly dates back to the 1970s combined with the previous studies we conclude that the karakoram glaciers as a whole were in a nearly balanced state during the 1970s to the 2010s

karakoram glacier surge dynamics quincey d j braun m glasser n f bishop m p hewitt k luckman a 2011 geophysical research letters 38 article number l18504

karakoram geodetic glacier mass balances between 2008 and 2016 persistence of the anomaly and influence of a large rock avalanche on siachen glacier karakoram glaciers experienced balanced or slightly positive mass budgets since at least the 1970s here we provide an update on the state of balance of central and eastern karakoram glaciers 12 000 km2 between 2008 and 2016 by differencing dems derived from satellite optical images the mass budget of central karakoram glaciers was slightly positive 0 12 0 14 m w e a 1 while eastern karakoram glaciers lost mass 0 24 0 12 m w e a 1 the glacier wide mass balances of surge type and nonsurge type glaciers were not statistically different our elevation change data also depict the effect of a 100 mm3 rock avalanche on siachen glacier ablation area in september 2010 it covered a 4 km2 area with a thick debris layer that unexpectedly led to locally enhanced glacier mass loss during the following years enhanced melt opened a 100 m deep 2 km2 depression and contributed to 6 of the mass loss of siachen glacier from 2010 to 2016 0 39 m w e a 1 we hypothesize that sub or englacial melt may be responsible for this intriguing behaviour this study contributes to a better knowledge of the regional pattern of the karakoram anomaly and of the influence of rock avalanches on glacier mass changes

climatic and geometric controls on the global distribution of surge type glaciers implications for a unifying model of surging financial support was provided by the conocophillips lundin northern area program project crios

geochemical and nd isotopic evolution of paleoproterozoic arc type granitoid magmatism in the flin flon belt trans hudson orogen canada granitoid magmatism spans three flin flon belt evolutionary stages i evolved arc 1920 ma plus early juvenile arc 1904 1880 ma plutonism during intraoceanic arc back arc formation ii early 1878 1860 ma and middle 1860 1844 ma successor arc plutonism following accretion and successor arc s development and iii late 1843 1826 ma successor arc plutonism accompanying successor basin formation and waning arc magmatism amphibole bearing mineralogy metaluminous compositions and igneous microgranitoid enclaves indicate derivation from infracrustal sources predominance of intermediate calc alkaline compositions and negative nb anomalies on normalized patterns over a 46 77 wt silica range indicate an arc setting basaltic end members indicate important contributions directly from the mantle e nd t values are predominately in the range 0 to 4 3 reflecting mixing between depleted mantle melts and an archean crustal component preserved in evolved arc plutons 3 9 to 6 temporal variations include the following i early juvenile arc plutons are low k high field strength element hfse depleted with relatively flat rare earth element ree patterns and negative eu anomalies indicative of low pressure partial melting fractionation in the mantle wedge with residual pyroxene and plagioclase ii early and middle successor arc plutonism is medium k with steep ree patterns and no eu anomalies indicative of input from melting of basaltic sources likely subducted back arc oceanic crust under high pressure conditions with residual garnet and or amphibole and no plagioclase iii late successor arc plutons are high k more hfse enriched with both variable ree pattern slopes and eu anomalies indicative of a significant petrogenetic role of recycling of preexisting juvenile arc accretionary complex crust

contrasting patterns of early twenty first century glacier mass change in the himalayas glaciers are among the best terrestrial climate indicators an important water resource in mountains1 2 and a major contributor to global sea level rise3 4 in the hindu kush karakoram himalaya region hkkh a paucity of appropriate glacier data has prevented a comprehensive assessment of current regional mass balance5 however there are indirect evidences of a complex pattern of glacial responses5 8 in reaction to heterogeneous climate change signals9 here we provide the first coherent data set of detailed glacier thickness changes over the hkkh during 2003 2009 by combining satellite laser altimetry and a global elevation model in the eastern central and south western parts of the hkkh glacier wastage is widespread with regional thinning rates up to 0 66 0 09 m a 1 in the jammu kashmir region conversely in the karakoram glaciers are close to balance with only a slight thinning of 0 07 0 04 m a 1 regionally averaged thinning rates under debris mantled ice are similar to those of clean ice despite insulation by debris covers the 2003 2008 specific mass balance for our hkkh study region is 0 21 0 05 m a 1 water equivalent we significantly less negative than the global average of 0 7 m a 1 we for glaciers and ice caps4 10 this difference is mainly an effect of the balanced glacier mass budget in the karakoram the corresponding hkkh sea level contribution is 0 035 0 009 mm a 1 amounting to 1 of the present day sea level rise11 our 2003 2008 mass budget of 12 8 3 5 gt a 1 is more negative than recent satellite gravimetry based estimates of 5 6 gt a 1 over 2003 2010 ref 12 for the mountain catchments of the indus and ganges basins13 the glacier imbalance contributes 3 5 and 2 0 respectively to the annual average river discharge13 and up to 10 for the upper indus basin14

response of debris covered glaciers in the mount everest region to recent warming and implications for outburst flood hazards abstract in areas of high relief many glaciers have extensive covers of supraglacial debris in their ablation zones which alters both rates and spatial patterns of melting with important consequences for glacier response to climate change wastage of debris covered glaciers can be associated with the formation of large moraine dammed lakes posing risk of glacier lake outburst floods glofs in this paper we use observations of glaciers in the mount everest region to present an integrated view of debris covered glacier response to climate change which helps provide a long term perspective on evolving glof risks in recent decades debris covered glaciers in the everest region have been losing mass at a mean rate of 0 32 m yr 1 although in most cases there has been little or no change in terminus position mass loss occurs by 4 main processes 1 melting of clean ice close to glacier elas 2 melting beneath surface debris 3 melting of ice cliffs and calving around the margins of supraglacial ponds and 4 calving into deep proglacial lakes modelling of processes 1 and 2 shows that everest region glaciers typically have an inverted ablation gradient in their lower reaches due to the effects of a down glacier increase in debris thickness mass loss is therefore focused in the mid parts of glacier ablation zones causing localised surface lowering and a reduction in downglacier surface gradient which in turn reduce driving stress and glacier velocity so the lower ablation zones of many glaciers are now stagnant model results also indicate that increased summer temperatures have raised the altitude of the rain snow transition during the summer monsoon period reducing snow accumulation and ice flux to lower elevations as downwasting proceeds formerly efficient supraglacial and englacial drainage networks are broken up and supraglacial lakes form in hollows on the glacier surface ablation rates around supraglacial lakes are typically one or two orders of magnitude greater than sub debris melt rates so extensive lake formation accelerates overall rates of ice loss most supraglacial lakes are perched above hydrological base level and are susceptible to drainage if they become connected to the englacial drainage system speleological surveys of conduits show that large englacial voids can be created by drainage of warm lake waters along pre existing weaknesses in the ice roof collapses can open these voids up to the surface and commonly provide the nuclei of new lakes thus by influencing both lake drainage and formation englacial conduits exert a strong control on surface ablation rates an important threshold is crossed when downwasting glacier surfaces intersect the hydrological base level of the glacier base level lakes formed behind intact moraine dams can grow monotonically and in some cases can pose serious glof hazards glacier termini can evolve in different ways in response to the same climatic forcing so that potentially hazardous lakes will form in some situations but not others additionally the probability of a flood is not simply a function of lake volume but depends on the geometry and structure of the dam and possible trigger mechanisms such as ice or rockfalls into the lake satellite based measurements of glacier surface gradient and ice velocities allow probable future locations of base level lakes to be identified a base level lake has begun to grow rapidly on ngozumpa glacier west of mount everest and could attain a volume of 10 8 m 3 within the next 2 or 3 decades unless mitigation efforts are undertaken this lake could pose considerable glof hazard potential

orbital time scale intra platform basin correlation carbon isotope stratigraphy and sea level history of the cenomanian turonian eastern levant platform jordan two cenomanian turonian boundary ctbe sections kb3 and gm3 of the karak silla intra platform basin of the eastern levant carbonate platform jordan are correlated based on high resolution calcimetry kb3 contains black shales with over 7 wt total organic carbon toc gm3 was deposited at shallower water depth and reveals four conspicuous gypsum beds used for sea level reconstruction spectral analysis of carbonate content and toc reveals forcing mainly by the 100 ka cycle of earth s orbit eccentricity whole rock stable carbon isotope data show a conspicuous positive d13c excursion representing the oceanic anoxic event 2 oae2 the carbon isotope records of kb3 and gm3 correspond well with the cycles in the dc record of the global stratotype gssp at pueblo usa the gssp orbital timescale thus can be applied to the jordan record furthermore all stable isotope events defined in the english chalk reference record are recognized in jordan our orbital model for the jordan sequence stratigraphical framework reveals approximately 1 2 0 2 ma duration of a third order sequence proposed to represent one cycle of the long obliquity 1 2 ma this longterm period is superimposed on three fourth order fluctuations of 400 ka length long eccentricity fourth order sea level fluctuations each of which comprises four carbonate cycles 100 ka eccentricity fifth order sea level fluctuations demise of the levant platform occurred during the phase of decreasing dc values after oae2 in the interval between the cenomanian turonian c t boundary and the end of the early turonian the levant carbonate platform deposits of central jordan represent a textbook like shallow marine platform setting subdivided into intra platform basins during cenomanian turonian c t times kuss et al 2003 the morphological structuring by these basins induced lithologically highly variable successions especially during black shale deposition that preferably occurred in deeper subbasins a correlation of these different successions is possible by means of high resolution calcimetry and stable carbon isotope stratigraphy in this paper we present such a correlation that enables the study of three research aspects a linking different palaeoenvironments over the c t boundary interval b refining the sequence stratigraphic model by constructing an orbital time scale c correlating the successions to the global record exemplified for the well dated c t boundary interval in order to eliminate ambiguities in the local stratigraphy furthermore our data support the global picture and estimates of duration of the c t boundary interval that includes the global oceanic anoxic event 2 oae2 the duration of oae2 has been the matter of many studies in recent years resulting in a range of values from 320 to 960 ka obradovitch 1993 sageman et al 2006 partly caused by considering different intervals an orbital timescale for the pueblo stratotype section was given by sageman et al 2006 providing a precise time measure for the period investigated in our study in addition a comprehensive study of stable carbon isotope records in europe was given by jarvis et al 2006 providing a detailed set of isotope events suitable for global correlation recently an orbital model was also presented for the wunstorf germany section voigt et al 2008 this record correlates well with the present results and can be used to support the new hypothesis put forward in the present paper regarding the orbital trigger of third order sequences

review of the status and mass changes of himalayan karakoram glaciers we present a comprehensive review of the status and changes in glacier length since the 1850s area and mass since the 1960s along the himalayan karakoram hk region and their climate change context a quantitative reliability classification of the field based mass balance series is developed glaciological mass balances agree better with remotely sensed balances when we make an objective systematic exclusion of likely flawed mass balance series the himalayan mean glaciological mass budget was similar to the global average until 2000 and likely less negative after 2000 mass wastage in the himalaya resulted in increasing debris cover the growth of glacial lakes and possibly decreasing ice velocities geodetic measurements indicate nearly balanced mass budgets for karakoram glaciers since the 1970s consistent with the unchanged extent of supraglacial debris cover himalayan glaciers seem to be sensitive to precipitation partly through the albedo feedback on the short wave radiation balance melt contributions from hk glaciers should increase until 2050 and then decrease though a wide range of present day area and volume estimates propagates large uncertainties in the future runoff this review reflects an increasing understanding of hk glaciers and highlights the remaining challenges

introduction to special issue of canadian journal of earth sciences the trans hudson orogen transect of lithoprobe dedication dr john f lewry 1939 1999 see saskatchewan geological survey 1999 dedicated his career to investigations of the saskatchewan manitoba segment of the trans hudson orogen tho one of the principal paleoproterozoic orogens associated with the assembly of laurentia indeed one can make a strong case that lithoprobe s trans hudson orogen transect thot was designed to test the tectonic models proposed by john lewry he delineated the distinct tectonic provinces in the western part of the tho predicted the presence of an archean craton trapped within the tho and recognized and interpreted the significance of the pelican thrust between the juvenile paleoproterozoic volcanic arc complex of the western flin flon domain and the archean craton now called the sask craton the research published in lewry and stauffer 1990 and many of his ideas provided the framework for the design of the thot geophysical and geological studies john lewry was co leader of the thot until he passed away in 19

spatially variable response of himalayan glaciers to climate change affected by debris cover the present state and future evolution of himalayan glaciers has been controversial an analysis of remotely sensed frontal changes and surface velocities from glaciers in the greater himalaya between 2000 and 2008 shows large regional variability in the responses of himalayan glaciers to climate change

late cretaceous ca 84 ma compressive deformation of the stable platform of northeast africa egypt far field stress effects of the santonian event and origin of the syrian arc deformation belt large scale northeast trending asymmetric folds and associated contractional faults seismically induced slump structures and strike slip and extensional faults of santonian age occur within the eastern desert of egypt 150 km south of the syrian arc mobile belt the region also displays a locally developed angular unconformity at the base of the flat lying campanian limestone these features demonstrate that the deformation event responsible for the syrian arc also led to northwest southeast shortening in central egypt ca 84 ma the late santonian shortening corresponds precisely with a brief period of compression that swept across the entire african plate coeval with a significant change in the poles of opening of the north atlantic this santonian event is a prominent example of the role that far field compressional stresses can play in stable intraplate settings

structural evolution of the eastern amisk collage trans hudson orogen manitoba deformation recorded in the amisk collage in the central part of the paleoproterozoic flin flon belt southeastern trans hudson orogen is divided into pre early late and post hudsonian orogeny distinguished by significant changes in metamorphic conditions and the orientation of structures detailed structural analysis petrography and high precision geochronology combined with previous mapping and geochemical studies indicate a structural history spanning 180 ma in the amisk collage and the database provides an excellent opportunity to study the structural evolution of precambrian greenstone belts accretion of the 1 92 1 88 ga tectono stratigraphic assemblages in the amisk collage began prior to 1 868 ga the deformational history records six generations of ductile structures f1 f6 followed by development of brittle ductile and brittle structures f7 which may have continued as late as 1 690 ga during exhumation of the collage the steep generally north northeast macroscopic structural g

upper cretaceous sequence stratigraphy of the galala plateaux western side of the gulf of suez egypt abstract based on the study of lithology biostratigraphy and analysis of facies this study deduces the occurrence of nine third order upper cretaceous cenomanian maastrichtian depositional sequences which are bounded by eleven sequence boundaries of geographic extent in the galala plateaux situated along the western side of the gulf of suez egypt some of the recorded sequence boundaries e g cenomanian turonian turonian coniacian intra santonian and campanian maastrichtian sequence boundaries are not yet confirmed to eustatic sea level changes fourteen main mixed carbonate siliciclastic facies associations were recognized on a lateral transition between inner to outer ramp settings with apparent subsidence towards the south the tectonic position of the galala plateaux played an important role in the profound complexity of facies changes and the configuration of depositional sequences representing variable time gaps

response of karakoram himalayan glaciers to climate variability and climatic change a regional climate model assessment the karakoram and the himalayan mountain range accommodate a large number of glaciers and are the major source of several perennial rivers downstream to interactively describe to response of glaciers to climate change a glacier parameterization scheme has been developed and implemented into the regional climate model remo the scheme simulates the mass balance as well as changes of the areal extent of glaciers on a subgrid scale the parameterization scheme is for the first time applied to the region a regional glacier inventory is compiled and is used to initialize glacier area and volume over the highly complex and data sparse region the simulated mass balance largely agrees with observations including the positive karakoram anomaly the simulated equilibrium line altitude is well captured although a systematic underestimation is apparent remo simulates the glacier climate interaction reasonably well it has clear potential to be used for future climate assessments

mass balance studies on siachen glacier in the nubra valley karakoram himalaya india the hydrological method is used to compute the mass balance of siachen glacier in the nubra valley karakoram himalaya india the method was chosen because of its suitability in rugged terrain analysis of precipitation data from the glacier as a function of altitude shows a power law relationship accumulation estimates based on this relationship show good agreement with the recorded precipitation the discharge data from the glacier show high runoff in the ablation seasons of 1986 87 1987 88 1989 90 and 1990 91 the mass balance calculations for these years are negative the lowest being in 1990 91 1084 mm positive mass balance in 1988 89 358 mm is attributed to comparatively heavy winter snowfall amounts and comparatively low temperatures during the ablation season significantly lower runoff was measured during this season negative mass balance values during 1989 90 and 1990 91 are a result of comparatively dry winters and comparatively warm ablation periods with monthly mean air temperatures 1 4 5 1 c higher at the beginning of the ablation season june and july than the mean of the last 5 years

glacier shrinkage across high mountain asia an assessment of glacier shrinkage reductionof area for all of high mountain asia requires a complete compilation of measured rates of change and also a methodology for objective comparison of rates i present a compilation from 155 publications reporting glacier area changes and also a method ology that overcomes the main obstacles hindering comparison glacier areas are not always assigned uncertainties and this problem is addressed with an error model derived from published estimates the problem of discordant survey dates is addressed by interpolating measured areas to fixed dates at pentadal intervals interpolation error depends only incoherently on the time span between measure ments but strongly on glacier size smaller glaciers in addition to changing more rapidly on average exhibit more variable rates of change the overlapping boundaries of study regions are reconciled by mapping all of the information to a 0 5 geographical grid when coupled with glacier area information from the randolph glacier inventory the widely observed inverse dependence of shrinkage rates on glacier size shows promise as a tool for treating incomplete spatial coverage over high mountain asia as a whole from 1960 to 2010 the unweighted average shrinkage rate is 0 57 a 1 but corrections for variable glacier size raise the average to 0 34 a 1 and filling unmeasured gridcells with rates based on size dependence alters the latter estimate to 0 40 a 1 the uncertainties in these rates are large the karakoram anomaly is found to be a zonal feature extending well to the east of the karakoram proper

a consensus estimate for the ice thickness distribution of all glaciers on earth knowledge of the ice thickness distribution of the world s glaciers is a fundamental prerequisite for a range of studies projections of future glacier change estimates of the available freshwater resources or assessments of potential sea level rise all need glacier ice thickness to be accurately constrained previous estimates of global glacier volumes are mostly based on scaling relations between glacier area and volume and only one study provides global scale information on the ice thickness distribution of individual glaciers here we use an ensemble of up to five models to provide a consensus estimate for the ice thickness distribution of all the about 215 000 glaciers outside the greenland and antarctic ice sheets the models use principles of ice flow dynamics to invert for ice thickness from surface characteristics we find a total volume of 158 41 103 km3 which is equivalent to 0 32 0 08 m of sea level change when the fraction of ice located below present day sea level roughly 15 is subtracted our results indicate that high mountain asia hosts about 27 less glacier ice than previously suggested and imply that the timing by which the region is expected to lose half of its present day glacier area has to be moved forward by about one decade the ice volume of glaciers outside the greenland and antarctic ice sheets totals about 158 000 km3 with about 27 less ice in high mountain asia than thought according to multiple models that estimate ice thickness from surface characteristics

the mid cretaceous carbonate system of northern israel facies evolution tectono sedimentary configuration and global control on the central levant margin of the arabian plate

rock avalanches that travel onto glaciers and related developments karakoram himalaya inner asia abstract catastrophic rock slope failures in rugged terrain commonly generate rock avalanches when these occur in glacier basins the extent of landslide run out and its emplacement geometry are affected by movement over ice substantial modifications of glacier activity and sedimentation can follow ice activity leads to rapid modification transport and dispersal of landslide debris the nature of these interactions is described from observations over 20 years at bualtar glacier in the karakoram in august 1986 rock avalanches descended onto the ablation zone of the glacier their moisture content and patterns of deposition were affected by travel over ice glacier movement increased sharply at and below the rock avalanche deposits and within a few months the glacier surged a second surge occurred 2 years later major slope failures and debris flows were triggered beyond the ice margins and ponded melt water led to small outburst floods by 2005 the landslide material had been transported some 9 km about one third of this distance in the surges eventually it was fully reworked to become less readily distinguishable from other heavy supraglacial debris a large area of thickened ice persisted where the debris reduced ablation a positive impact on mass balance equivalent to a 20 increase in annual accumulation however it occurred as a moving segment of the ablation zone in 10 years it had in effect replaced the mass transferred in the surges data for the mid 1980s indicate the rock avalanches exceeded pre existing supraglacial debris by roughly five times and over a 30 year period will equal almost 500 years of normal supraglacial transport to the glacier margins other impacts of the episode suggest a doubling of this contribution to denudation similar developments were observed at three other glaciers where recent rock avalanches occurred and at twenty one prehistoric rock avalanches newly identified as having spread over glaciers it seems inadequate to treat such events only as singular extremes or the landslide and glacial processes separately here they are interpreted as contributing to disturbance regime landscapes whose history reflects episodic and regionally specific responses to strong interference among different earth surface processes they generate polygenetic deposits and landforms that are morphologically complex individual episodes involve decades to millennia their numbers and repetition can over ride or redirect geotectonic and climatic conditions it is suggested they are major but hitherto misread or neglected elements of landform evolution in the karakoram and perhaps in other high mountains

the sask craton and hearne province margin seismic reflection studies in the western trans hudson orogen a three dimensional model of the regional crustal architecture of the western trans hudson orogen based on the interpretation of 590 km of deep sounding seismic reflection data and a comparable length of existing seismic reflection information is presented the seismic images identify the regional geometry of the basal detachment zone pelican thrust that separates juvenile allochthonous terranes from the underlying archean microcontinent sask craton the sask craton is inferred to have a minimum spatial extent of over 100 000 km2 with an associated crustal root that extends for 200 km along strike during terminal collision complete convergence of the rae hearne and superior continental blocks was precluded by the presence of the sask craton resulting in the preservation of anomalous amounts of oceanic and associated sedimentary juvenile material along regional tectonic strike consistency of crustal structure across the rae hearne margin reindeer zone boundary is established several phases of

age and origin of the jan lake complex a glimpse at the buried archean craton of the trans hudson orogen the largely buried sask craton is a continental fragment or microcontinent that collided with and underthrust the paleoproterozoic flin flon glennie protocontinent along the pelican decollement zone at 1840 1830 ma rocks of the sask craton are exposed in three tectonic windows those of the pelican window have been named the jan lake complex and comprise 2960 ma arc derived leucocratic orthogneisses migmatitic paragneisses and a tholeiitic within plate igneous suite comprising 2488 ma dioritic to gabbroic rocks and 2450 ma enderbitic and charnockitic rocks including the sahli granite ages of ca 2450 ma are also common from the other two tectonic windows to the sask craton suggesting that emplacement of the igneous suite was widespread and perhaps part of the coeval matachewan igneous event the absence of rocks in the 2960 and ca 2450 ma age ranges on both the adjacent superior and rae hearne cratonic margins makes it improbable that the sask craton was derived by simple fragmentation without large scale tectonic transport the overthrust paleoproterozoic rocks represent a high grade northwestern extension of the flin flon volcanic belt and include 1856 ma leucotonalite and 1843 ma quartz monzodiorite an 1830 ma suite of homogeneous calc alkaline enderbitic rocks which intrude burntwood semipelitic migmatites throughout the kisseynew domain has also been emplaced in mylonites of the pelican decollement zone zircon and monazite ages in the 1812 1803 ma range record a high grade metamorphic event that resulted from collision between the sask craton and flin flon glennie complex

sequence stratigraphy and evolution of the paleoproterozoic intracontinental baker lake and thelon basins western churchill province nunavut canada abstract the baker lake and thelon basins lie along the border between the rae and hearne domains of the western churchill province basin fill comprises the dubawnt supergroup a ca 1 85 1 70 ga succession of predominantly continental clastic and intercalated volcanic rocks that nonconformably and unconformably overlies granitic and supracrustal rocks most of late archean age the dubawnt supergroup comprises three second order sedimentary sequences that record deposition within a rift basin a modified rift basin and a thermal sag basin respectively the baker sequence is inferred to represent the principal phase in the development of baker lake basin a series of generally elongate northeast striking half graben and fault bounded troughs filled with continental redbeds and coeval voluminous ultrapotassic volcanic rocks faults parallel to the basin margin exhibit evidence for strike slip ca 1 83 1 81 ga the nature and timing of basin development and associated magmatism allows that it may be a transtensional basin that formed by lateral escape in response to crustal thickening during the trans hudson orogeny similar to the formation of mesozoic and cenozoic strike slip and associated rift basins on the margins of the tibetan plateau the overlying whart sequence was deposited in small basins formed by block faulting and tilting of the baker sequence basin fill comprises eolian and alluvial redbeds with intercalated rhyolite flows and epiclastic rocks distribution of facies and stratigraphy suggest that faulting occurred throughout deposition of the whart sequence but ceased before deposition of the overlying barrens sequence ca 1 72 ga deformation and basin formation can be linked to a regional episode of granite emplacement and associated thermal metamorphism ca 1 76 1 75 ga the barrens sequence represents deposition over a broader area primarily in thelon basin strata generally are thinner and flatter than underlying sequences and display lateral continuity indicating minimal influence from syndepositional faulting the depositional record reflects progressive upward fining and eventually the first record of marine transgression within the dubawnt supergroup these features suggest that the barrens sequence was deposited over a broad region of thermal subsidence likely related to cooling of previously attenuated continental lithosphere the barrens sequence may be a remnant of a huge cratonic sand sheet that included the thelon athabasca amundsen and elu basins a regional subsidence mechanism to account for these basins may be mantle downwelling linked to the late stage amalgamation of laurentia the tripartite sequence evolution of the baker lake and thelon basins represents a framework for future sequence correlation among late paleoproterozoic basins in laurentia and shares characteristics with the evolution of contemporaneous intracontinental basins from north central australia and southeastern brazil

paleoproterozoic 1 90 1 86 ga arc volcanism in the flin flon belt trans hudson orogen canada geochemical and isotopic nd sr data are reported on paleoproterozoic 1904 1864 ma maficintermediate 1870 ma collision and subsequent intra arc deformation

glacier mass balance in the qinghai tibet plateau and its surroundings from the mid 1970s to 2000 based on hexagon kh 9 and srtm dems abstract in the context of global warming glacier changes in the qinghai tibet plateau qtp and its surroundings have attracted a great amount of public attention to date there have been many studies of glacier mass balance across the qtp however given that most of the previous studies have focused on a short observation period 2000 2015 and that long term mass change measurements are available only for some local regions we utilized declassified kh 9 images and 1 arc second shuttle radar topography mission srtm digital elevation models dems to provide the region wide mass balance from the mid 1970s to 2000 for a larger scale including 11 sample regions across the qtp and its surroundings the final results indicate that the glaciers in the northwest of the qtp have shown a less negative or near zero mass balance ranging from 0 11 0 13 m w e a 1 to 0 02 0 10 m w e a 1 compared to those in the southeast part with a mass balance range of 0 30 0 12 m w e a 1 to 0 11 0 14 m w e a 1 the most serious mass loss has emerged in the central eastern himalaya integrating our results with the observations after 2000 suggests that over the past four decades mid 1970s to the mid 2010s the glaciers in the himalaya nyainqentanglha and tanggula mountains as a whole have exhibited accelerated mass loss and the most significant acceleration has occurred in the eastern nyainqentanglha moreover the hindu raj glaciers have shown a stable rate of continuous mass loss while a nearly stable or slight mass gain state in the western kunlun region can be dated back to at least as far as the mid 1970s

regional mapping of precambrian basement beneath phanerozoic cover in southeastern trans hudson orogen manitoba and saskatchewan the northern edge of phanerozoic platformal rocks of the western canada sedimentary basin overlies the flin flon belt trans hudson orogen in manitoba and saskatchewan a program of regional mapping of the phanerozoic covered basement has been undertaken involving the integration of high resolution aeromagnetic and gravity data with extensive drill core information several major domains are recognized in the buried basement each with a distinct lithotectonic character and potential field anomaly pattern three lithotectonic domains in the buried basement clearwater athapapuskow and amisk lake domains are characterized by northerly trending positive gravity and aeromagnetic anomalies and correlate with the 1 92 1 83 ga volcanic and plutonic rocks of the exposed flin flon belt amisk collage and snow lake assemblage an upper amphibolite grade orthogneiss complex namew gneiss complex containing calc alkaline intrusive rocks ranging in age from 1 88 to 1 83 ga and screens derived from the older v

are karakoram temperatures out of phase compared to hemispheric trends in contrast to a global retreating trend glaciers in the karakoram showed stability and or mass gaining during the past decades this karakoram anomaly has been assumed to result from an out of phase temperature trend compared to hemispheric scales however the short instrumental observations from the karakoram valley bottoms do not support a quantitative assessment of long term temperature trends in this high mountain area here we presented a new april july temperature reconstruction from the karakoram region in northern pakistan based on a high elevation 3600 m a s l tree ring chronology covering the past 438 years ad 1575 2012 the reconstruction passes all statistical calibration and validation tests and represents 49 of the temperature variance recorded over the 1955 2012 instrumental period it shows a substantial warming accounting to about 1 12 c since the mid twentieth century and 1 94 c since the mid nineteenth century and agrees well with the northern hemisphere temperature reconstructions these findings provide evidence that the karakoram temperatures are in phase rather than out of phase compared to hemispheric scales since the ad 1575 the synchronous temperature trends imply that the anomalous glacier behavior reported from the karakoram may need further explanations beyond basic regional thermal anomaly

intraoceanic tectonics and the development of continental crust 1 92 1 84 ga evolution of the flin flon belt canada the flin flon belt is a complex amisk collage of distinct tectono stratigraphic assemblages that was brought together at a relatively early stage in the tectonic evolution of the paleoproterozoic trans hudson orogen four main tectono stratigraphic assemblage types are recognized isotopically juvenile oceanic arc 1 90 1 88 ga ocean floor ca 1 90 ga oceanic plateau ocean island and isotopically evolved arc 1 92 1 90 ga oceanic arc assemblages include tholeiitic calc alkaline and lesser shoshonitic volcanic and volcaniclastic rocks as well as turbidites and arc rift volcanic rocks the tectono stratigraphic assemblages were juxtaposed in an accretionary complex amisk collage at ca 1 88 1 87 ga probably as a result of arc arc collision collisions accretionary collage structures are largely obliterated by subsequent deformation and metamorphic events but can be inferred where cut by calc alkaline plutons related to a 1 866 1 838 ga arc coeval subaerial volcanism is recorded in ca 1 87 1 85 ga calc alkaline to shoshonitic volcaniclastic sequences unroofing of the accretionary collage development of a paleosol and deposition of continental alluvial fluvial sedimentary rocks occurred ca 1 85 1 84 ga coeval with the waning stages of post accretion arc magmatism stabilization of the flin flon belt by 1 85 1 84 ga as part of a philippines or japan like microcontinent is attributed to both tectonic and magmatic thickening of the lithosphere

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

ice ablation and meteorological conditions on the debris covered area of baltoro glacier karakoram pakistan during the recent italian expedition k2 2004 50 years later june july 2004 on baltoro glacier karakoram pakistan glaciological field experiments were carried out on the debris covered area of this high elevation glacier the aim was to investigate the ice ablation and its relations with debris thermal properties and meteorological conditions ablation measurements along the glacier up to about 5000 m and within a dedicated test field were combined with meteorological data from two automatic weather stations located at urdukas 4022 m a s l and at k2 base camp 5033 m a s l in addition temperature measurements of the debris cover at different depth levels along the glacier allowed the calculation of debris surface temperature and of the debris thermal resistance r using the air temperature the local mean lapse rate 0 00758 cm 1 and the measured ablation the degree day factors k at different locations on the glacier were calculated the ice ablation rates were related to debris thickness and elevation they are typically on the order of 4 cm d 1 during the observation period however it was found that the surface topography slope aspect has an influence on the total ablation similar to that of the debris thickness thermal resistance of the debris cover and its distribution over the glacier were estimated finally a best guess estimate of the total meltwater production was calculated from available climate data

introduction to special issue 2 on the natmap shield margin project the flin flon belt trans hudson orogen manitoba and saskatchewan the shield margin project of the national geoscience mapping program natmap resulted in a new understanding of the paleoproterozoic flin flon belt manitoba and saskatchewan in four dimensions

a spatially resolved estimate of high mountain asia glacier mass balances from 2000 to 2016 glacier mass balances in high mountain asia are uncertain satellite stereo imagery allows a spatially resolved estimate for about 92 of the glacierized area and yields a region wide average of about 16 gt yr 1 for 2000 to 2016

massive collapse of two glaciers in western tibet in 2016 after surge like instability surges and glacier avalanches are expressions of glacier instability and among the most dramatic phenomena in the mountain cryosphere until now the catastrophic collapse of a glacier combining the large volume of surges and mobility of ice avalanches has been reported only for the 2002 130 106 m3 detachment of kolka glacier caucasus mountains which has been considered a globally singular event here we report on the similar detachment of the entire lower parts of two adjacent glaciers in western tibet in july and september 2016 leading to an unprecedented pair of giant low angle ice avalanches with volumes of 68 2 106 m3 and 83 2 106 m3 on the basis of satellite remote sensing numerical modelling and field investigations we find that the twin collapses were caused by climate and weather driven external forcing acting on specific polythermal and soft bed glacier properties these factors converged to produce surge like enhancement of driving stresses and massively reduced basal friction connected to subglacial water and fine grained bed lithology to eventually exceed collapse thresholds in resisting forces of the tongues frozen to their bed our findings show that large catastrophic instabilities of low angle glaciers can happen under rare circumstances without historical precedent two catastrophic glacier collapse events in western tibet in 2016 were caused by a convergence of weather and glacier bed conditions according to an analysis of observations and modelling

heterogeneity in karakoram glacier surges many karakoram glaciers periodically undergo surges during which large volumes of ice and debris are rapidly transported downglacier usually at a rate of 1 2 orders of magnitude greater than during quiescence here we identify eight recent surges in the region and map their surface velocities using cross correlation feature tracking on optical satellite imagery in total we present 44 surface velocity data sets which show that karakoram surges are generally short lived lasting between 3 and 5 years in most cases and have rapid buildup and relaxation phases often lasting less than a year peak velocities of up to 2 km a 1 are reached during summer months and the surges tend to diminish during winter months otherwise they do not follow a clearly identifiable pattern in two of the surges the peak velocity travels down ice through time as a wave which we interpret as a surge front three other surges are characterized by high velocities that occur simultaneously across the entire glacier surface and acceleration and deceleration are close to monotonic there is also no consistent seasonal control on surge initiation or termination we suggest that the differing styles of surge can be partly accounted for by individual glacier configurations and that while some characteristics of karakoram surges are akin to thermally controlled surges elsewhere e g svalbard the dominant surge mechanism remains unclear we thus propose that these surges represent a spectrum of flow instabilities and the processes controlling their evolution may vary on a glacier by glacier basis

a reconciled estimate of glacier contributions to sea level rise 2003 to 2009 glaciers distinct from the greenland and antarctic ice sheets are losing large amounts of water to the world s oceans however estimates of their contribution to sea level rise disagree we provide a consensus estimate by standardizing existing and creating new mass budget estimates from satellite gravimetry and altimetry and from local glaciological records in many regions local measurements are more negative than satellite based estimates all regions lost mass during 2003 2009 with the largest losses from arctic canada alaska coastal greenland the southern andes and high mountain asia but there was little loss from glaciers in antarctica over this period the global mass budget was 259 28 gigatons per year equivalent to the combined loss from both ice sheets and accounting for 29 13 of the observed sea level rise

twenty first century glacier slowdown driven by mass loss in high mountain asia glaciers in high mountain asia have experienced heterogeneous rates of loss since the 1970s yet the associated changes in ice flow that lead to mass redistribution and modify the glacier sensitivity to climate are poorly constrained here we present observations of changes in ice flow for all glaciers in high mountain asia over the period 2000 2017 based on one million pairs of optical satellite images trend analysis reveals that in 9 of the 11 surveyed regions glaciers show sustained slowdown concomitant with ice thinning in contrast the stable or thickening glaciers of the karakoram and west kunlun regions experience slightly accelerated glacier flow up to 94 of the variability in velocity change between regions can be explained by changes in gravitational driving stress which in turn is largely controlled by changes in ice thickness we conclude that despite the complexities of individual glacier behaviour decadal and regional changes in ice flow are largely insensitive to changes in conditions at the bed of the glacier and can be well estimated from ice thickness change and slope alone changes in glacier speed in high mountain asia are closely linked to mass balance through gravitational driving stress and largely insensitive to basal conditions according to satellite derived ice flow observations

stratigraphic and tectonic setting of early proterozoic volcanogenic massive sulfide deposits flin flon manitoba volcanogenic massive sulfide deposits in the flin flon metavolcanic belt occur in an early proterozoic island arc setting that includes arc tholelite back arc ocean floor and shoshonitic assemblages near the town of flin flon manitoba these volcanic assemblages are structurally juxtaposed in a tectonic collage nearly all of the volcanogenie massive sulfide deposits at flin flon are associated with the arc tholeiite assemblage and occur in complex stratigraphic sequences which represent volcanic constructs and associated intravolcanic basins within the former magmatic arc back arc or ocean floor basalts in the flin flon belt host only a few small cu rich massive sulfide deposits and consequently have a lower exploration potential than the arc tholeiite assemblage within the arc tholeiite assemblage volcanogenie massive sulfide deposits occur in association with felsic volcanic units at major stratigraphic and compositional breaks in the volcanic sequence the breaks can be recognized by contrasting major element trace element and isotopic characteristics of the underlying and overlying mafic rocks most volcanogenie massive sulfide deposits are underlain by coarse mafic intermediate or felsic volcaniclastic rocks the best documented examples including the flin flon cuprus and white lake deposits discussed in this paper are clearly localized in basinal structures that vary widely in size the flin flon deposit 62 4 mt occurs in a proximal volcanic environment it lies on the upper flank of a shallow subaqueous basalt volcano possibly in a fault bounded depression the massive sulfides are emplaced within a rhyolite flow complex and are underlain by a disconformable chloritic hydrothermal alteration zone developed in footwall basalt breccia the massive sulfides were overlain by a thick 3 km subaqueous basalt basaltic andesite succession compositionally unrelated to basalts in the stratigraphic footwall the cuprus and white lake deposits total 1 3 mt occur in a 5 5 km thick sequence dominated by more than 3 km of basaltic andesitc interpreted as a subaqueous shield volcano this volcano contains a collapse caldera within which an intracaldera subaqueous rhyolite flow and coeval felsic and intermediate basin filling volcaniclastic rocks were deposited massive sulfides accumulated in subbasins within the caldera hosted by a thin unit of graphitic mudstone and chert overlying formations are laterally extensive unlike the wedgeshaped caldera filling deposits and were deposited in a large deep water basin these rocks are chemically and isotopically unrelated to formations underlying the massive sulfide deposit

geological structure of the eastern side of the lower jordan valley dead sea rift reflection seismic evidence abstract interpretation of recently released seismic reflection lines from the shuna eastern jericho basin combined with re analysis of the lithologic logs of the deep jv 1 and jv 2 boreholes provide new insights into the structure of the sedimentary basin that formed along the dead sea transform fault north of the dead sea in jordan we identified four major seismic boundaries in the reflection profiles the upper two were correlated with borehole stratigraphy these reflection boundaries include the top of the pan african basement r4 the base of the mesozoic r3 the base of the cretaceous r2 and the base of the post eocene section r1 the latter records sedimentation during the dead sea transform tectonic regime the total thickness attained by the older sedimentary units late cretaceous through cambrian is apparently less than 2 km we identified a subsurface structure a faulted monocline with a n s trend sub parallel to the strike of the dead sea transform that is named here al kharrar monocline the al kharrar structural ensemble is buried by syntectonic lacustrine and fluviatile sediments of the jordan valley group the structure formed as part of the dead sea transform deformation overprinting the late cretaceous syrian arc folds continued tectonic deformation is evident from the prominent unconformity at the base of post eocene syntectonic deposits that dip nw w and s away from the structural high along the nw flank of the al kharrar monocline syntectonic sediment thickness is generally less than 0 5 km while along the sw flank it thickens rapidly to nearly 1 km at the southern end of the interpreted seismic lines this rapid southern subsidence probably continues into the north end of the dead sea basin the lake s shoreline being located less than 3 km to the south young bifurcating faults with reverse slip components cutting the eastern part of the al kharrar monocline are attributed to a positive flower structure this pattern suggests strike slip with localized active compression northeast of the dead sea it may result from local transpression between fault strands that appear to be a northward continuation of the eastern boundary fault of the dead sea basin

what drove sea level fluctuations during the mid cretaceous greenhouse climate the major states in which earth s climate operates i e icehouse greenhouse and hothouse are epochs of tens of millions of years these states set long term boundary conditions that need to be considered for climate and sea level interpretations this paper summarizes the conceptual models for hydrological cycling derived from the characteristics of these three climate states while glacio eustatic forcing of sea level changes under icehouse climate conditions is fairly well understood the drivers of eustatic sea level fluctuations under greenhouse conditions remain enigmatic this lack of understanding may be related to incoherencies in the current ideas about the impact of accelerated hydrological cycling on sea level under greenhouse climate conditions as an example for a greenhouse climate we review evidences that link proxies for climate and sea level for the intensely studied but controversially discussed mid cretaceous sea level history based on sequence stratigraphy and a recently published high precision timescale we demonstrate that the late middle turonian pewsey 13c isotope maximum represents a major transgression not a regression as previously stated which conflicts with the interpretation of a co occurring 18o maximum to reflect a short glacial episode this contradiction can be solved by the concept presented here that dominance of aquifer eustasy characterized sea level forcing during the turonian greenhouse climate despite a possible though contentious sporadic presence of minor ice sheets the effects of temperature and ice volume both lead to a pronounced 18ocarb maximum during glacio eustatic regressions in contrast the opposing effects of temperature and groundwater volume on oxygen isotope fractionation lead to a 18ocarb maximum during aquifer eustatic transgressions we suggest that throughout earth history both aquifer eustatic and glacio eustatic forcing formed a combined sea level response with dominance of aquifer eustasy being typical for the greenhouse climate mode during the icehouse mode aquifer eustasy apparently remains active as a background process but is outpaced by the glacio eustatic effect

u pb geochronology of late neoarchean tonalites in the flin flon belt trans hudson orogen surprise at surface the flin flon volcanic belt of the trans hudson orogen in northern manitoba comprises magmatic rocks 1 88 1 90 ga generated in an intra oceanic arc and identified as one of the best examples of juvenile paleoproterozoic crust in the flin flon athapapuskow lake area the belt consists of a series of fault bounded blocks each having distinct stratigraphic and magmatic affinities juxtaposed to form an accretionary collage two tonalitic bodies within the northeast arm shear zone a major deformation corridor separating two of the most important blocks in the area have been dated by the u pb zircon method at and these results indicate the presence of fragments of late neoarchean crust within the flin flon belt possibly related to ca 2 5 ga granitic bodies found in terranes beyond the western limit of the belt the presence of ca 2 5 ga tonalites within the flin flon belt herein reported for the first time has major implications for basement involvement in the early tectonic evolution of the f

flin flon belt seismic anisotropy elastic symmetry heterogeneity and shear wave splitting laboratory measurements of compressional and shear wave velocities and shear wave splitting have been carried out on a set of upper greenschist lower amphibolite facies of metasediments and metavolcanics and plutonic rocks from two ductile shear zones in the flin flon belt ffb of the trans hudson orogen tho selected metamorphic rocks vary in composition from felsic to mafic test sites with outcrops of sheared metamorphic rocks were correlated with a series of inclined seismic reflectors possibly extending from the midcrust and intersecting a well mapped shear zone at the surface determination of the lithological and physical properties of highly deformed metamorphic rocks is essential for proper interpretation of the nature of observed seismic reflectors to investigate the anisotropic properties of the rocks compressional velocity was measured at confining pressure up to 300 mpa in three mutually orthogonal directions aligned with respect to visible textural features in addition on selected

how much do we really know about glacier surging some of the ideas about glacier surging are considered mainly but not entirely in the light of observations of temperate glaciers in alaska u s a made within the last 15 years climate has an influence on surge recurrence interval climate and weather also affect surge initiation termination and magnitude regional studies lead to the speculation that subglacial till plays a key role in surging and it has been found under all surge type glaciers studied so far including black rapids and variegated glaciers alaska in most of the glaciers studied till deformation processes dominate the motion in quiescence the linked cavity model of surge triggering and rapid motion is not consistent with these observations but the limited coverage of the observations does not rule it out under parts of the glaciers studied the till observations in alaska raise old questions about the interaction between till and the hydraulic systems of temperate glaciers the role of stored water which observations show to be active even in winter on black rapids glacier is noted

tributary glacier surges an exceptional concentration at panmah glacier karakoram himalaya four tributaries of panmah glacier have surged in less than a decade three in quick succession between 2001 and 2005 since 1985 13 surges have been recorded in the karakoram himalaya more than in any comparable period since the 1850s ten were tributary surges in these ten a full run out of surge ice is prevented but extended post surge episodes affect the tributary and main glacier the sudden concentration of events at panmah glacier is without precedent and at odds with known surge intervals for the glaciers interpretations must consider the response of thermally complex glaciers at exceptionally high altitudes and of high relief to changes in a distinctive regional climate it is suggested that high altitude warming affecting snow and glacier thermal regimes or bringing intense short term melting episodes may be more significant than mass balance change

a surge of bualtar glacier karakoram range pakistan a possible landslide trigger bualtar glacier karakoram range northern pakistan surged during the spring and early summer of 1987 this followed a major episode of three landslides which impacted part of the glacier ablation zone on 30 31 july 1986 in may 1987 surface velocities of 7 m d 1 were measured at one profile down glacier from the landslide deposits where in 1986 velocities were an order of magnitude less surface and hydrological characteristics of the glacier in and down glacier from the landslide deposit were also indicative of surge like behavior in 1987 and a return to pre surge conditions by 1988

depositional environments and paleogeography of the cretaceous gypsum horizon in west central jordan abstract in the upper cretaceous upper cenomanian gypsum horizon of west central jordan the lithofacies of gypsum limestone and dolomite as well as their sedimentary structures and petrography indicate a coastal intertidal supratidal sabkha environment very much like the persian gulf model 1500 km 2 in area and elongated n s parallel to the dead sea rift fact that this is the second time in the cenomanian of the mujib area that total emergence has happened is taken as an example of synsedimentary tectonics in an unstable area along the not yet existing dead sea rift

plagioclase preferred orientation and induced seismic anisotropy in mafic igneous rocks fractional crystallization and crystal segregation controlled by settling or floating of minerals during the cooling of magma can lead to layered structures in mafic and ultramafic intrusions in continental and oceanic settings in the lower crust thus the seismic properties and fabrics of layered intrusions must be calibrated to gain insight into the origin of seismic reflections and anisotropy in the deep crust to this end we have measured p and s wave velocities and anisotropy in 17 plagioclase rich mafic igneous rocks such as anorthosite and gabbro at hydrostatic pressures up to 650 mpa anorthosites and gabbroic anorthosites containing 80 vol plagioclase and gabbros consisting of nearly equal modal contents of plagioclase and pyroxene display distinctive seismic anisotropy patterns vp z vp y 1 and vp z vp x 1 for anorthosites while 0 8 vp y than the gabbros laminated anorthosites with vp x vp y vp z display a strong crystal preferred orientation cpo of plagioclase whose 010 planes and 100 and 001 directions parallel to the foliation for the gabbros and amphibolites characterized by vp x vp y vp z and vp x vp y vp z respectively pyroxene and amphibole play a dominant role over plagioclase in the formation of seismic anisotropy the poisson s ratio calculated using the average p and s wave velocities from the three principal propagation polarization directions x y and z of a highly anisotropic anorthosite cannot represent the value of a true isotropic equivalent the cpo induced anisotropy enhances and decreases the foliation normal incidence reflectivity at gabbro peridotite and anorthosite peridotite interfaces respectively

glacier velocities across the central karakoram optical matching of aster advanced spaceborne thermal emission and reflection radiometer satellite image pairs is used to determine the surface velocities of major glaciers across the central karakoram the aster images were acquired in 2006 and 2007 and cover a 60 120 km region over baltoro glacier pakistan and areas to the north and west the surface velocities were compared with differential global position system gps data collected on baltoro glacier in summer 2005 the aster measurements reveal fine details about ice dynamics in this region for example glaciers are found to be active over their termini even where they are very heavily debris covered the characteristics of several surge type glaciers were measured with terminus advances of several hundred meters per year and the displacement of trunk glaciers as surge glaciers pushed into them this study is the first synthesis of glacier velocities across this region and provides a baseline against which both past and future changes can be compared

a general theory of glacier surges we present the first general theory of glacier surging that includes both temperate and polythermal glacier surges based on coupled mass and enthalpy budgets enthalpy in the form of thermal energy and water is gained at the glacier bed from geothermal heating plus frictional heating expenditure of potential energy as a consequence of ice flow enthalpy losses occur by conduction and loss of meltwater from the system because enthalpy directly impacts flow speeds mass and enthalpy budgets must simultaneously balance if a glacier is to maintain a steady flow if not glaciers undergo out of phase mass and enthalpy cycles manifest as quiescent and surge phases we illustrate the theory using a lumped element model which parameterizes key thermodynamic and hydrological processes including surface to bed drainage and distributed and channelized drainage systems model output exhibits many of the observed characteristics of polythermal and temperate glacier surges including the association of surging behaviour with particular combinations of climate precipitation temperature geometry length slope and bed properties hydraulic conductivity enthalpy balance theory explains a broad spectrum of observed surging behaviour in a single framework and offers an answer to the wider question of why the majority of glaciers do not surge

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

kisseynew metasedimentary gneiss belt trans hudson orogen canada back arc origin and collisional inversion the kisseynew metasedimentary gneiss belt initially developed in a back arc setting the ages of detrital zircons and crosscutting plutons constrain turbidite sedimentation to 1 855 1 841 ga postdating early deformation and metamorphism associated with arc arc and arc continent collisions affecting much of the trans hudson orogen these turbidites are interpreted to have been deposited in a back arc basin behind a retreating subduction boundary the kisseynew domain and its southern flank are marked by 1 84 1 83 ga magmatic rocks that may be related to subduction of back arc basin oceanic crust collapse of the kisseynew basin by ductile fold and thrust deformation began during 1 84 1 83 ga magmatism and continued through peak metamorphism at ca 1 820 1 805 ga from authors

glacier surges in the north west west kunlun shan inferred from 1972 to 2017 landsat imagery the west kunlun shan lie close to or are perhaps part of two significant glaciological phenomena the high mountain asia surge supercluster and the karakoram anomaly however glaciological studies and particularly surge studies in the range are limited here we extend the database of known surges in the region using landsat imagery and cross correlation feature tracking we examine 88 glaciers larger than 1 km2 in the hotan prefecture of xinjiang china and find evidence of nine surges occurring between 1972 and 2017 glaciers display low active phase velocities 0 2 1 5 km a 1 that show seasonal acceleration in the summer active phase periods as short as 2 years and build up and deceleration phases of months years although these observations display characteristics indicative of both the classic hydrological and thermal switch mechanisms the surging observed displays a close resemblance to that in the adjacent karakoram ranges furthermore the majority of the surges occur clustered at the end of a decadal scale warming period corroborating previously proposed causal links between climate and surging in the karakoram we suggest that the two regions should be considered part of one larger system when considering surge dynamics in high mountain asia

transgressions regressions and relative sea level changes on the cretaceous shelf of israel and adjacent countries a critical evaluation of cretaceous global sea level correlations cretaceous transgressive regressive cycles over the northern margins of the arabo nubian craton in the region of present day israel and the adjacent countries were reconstructed by tracing the position of the ancient tethyan shorelines many of these cycles suggest inverse relationships to the relative sea level changes deduced from litho and biofacies analyses transgressions are frequently associated with shallowing resulting in local exposure the following rapid relative sea level rise is associated with regressive oscillations caused by prograding sedimentation generally the relative sea level gradually rose throughout the cretaceous as reflected by the onlapping trend of the marine sediments with the exception of one greater relative sea level drop in the middle turonian probably tectonically induced all other relative sea level variations were short stillstands and very minor falls the dominant tectonic control on the relative sea level changes and transgressive regressive cycles during the late coniacian maastrichtian times and on the middle turonian and early late coniacian shallowing events recognised in israel render their previous attribution exclusively to eustasy erroneous the opposing relationship between relative bathymetric changes and transgressive regressive tendencies as well as the poor biostratigraphic control in many of the sea level curves compiled on the basis of these two criteria raise additional doubts as to their presumed significance for global correlations the present study supports jeletzky s 1977 1978 critical analysis and his call for similar critical re evaluation of previous studies throughout the world rather than the emendation of data to improve correlation to a given scheme

alluvial eolian and lacustrine sedimentology of a paleoproterozoic half graben baker lake basin nunavut canada the northeast trending baker lake sub basin was a volcanically active half graben during deposition of ca 1 85 1 76 ga baker lake group drainage was oriented along transverse and axial directions with flow to playa lake and deeper perennial lacustrine depocentres basin marginal streamflow dominated alluvial fans were concentrated along the southern margin and provided sediment from archean crystalline basement rocks these fed transverse gravel and sand bed braided streams alluvial dynamics were characterized by channel aggradation and abandonment abandoned channel belts were sites of floodplain and eolian deposition basin axial braided streams fed northeast and southwest to a depocentre near christopher island where eolian playa and lacustrine environments were intimately linked felsic minette flows were initially erupted from localized centres contemporaneous sedimentary deposits typically contain minor volcaniclastic components that increase in abundance basinward voluminous and widespread younger minette flows prograded outward from volcanic centres contributing significant additional basin infill

new perspectives on the flin flon belt trans hudson orogen manitoba and saskatchewan an introduction to the special issue on the natmap shield margin project part 1 a new tectonic framework for the flin flon belt in southeastern reindeer zone of the trans hudson orogen has emerged in recent years through four dimensional studies bedrock and subsurface mapping

glaciological characteristics of the ablation zone of baltoro glacier karakoram pakistan baltoro glacier in the karakoram pakistan is one of the world s largest valley glaciers it drains an area of about 1500 km 2 and is 60km long in 2004 an italian german expedition carried out a glaciological field program on the ablation zone of the glacier focusing on the ablation conditions and the dynamic state of the glacier as baltoro glacier is a debris covered glacier ice ablation also depends on the debris properties stake measurements of ice ablation and debris cover in combination with meteorological data from automatic weather stations close by have been used to determine the local melt conditions results from these calculations have been combined with an analysis of different classes of surface cover and information about precipitation using remote sensing techniques in order to calculate mass fluxes for the upper part of baltoro glacier the dynamic state of the glacier has been investigated by gps based surface velocity measurements along the stake network a comparison of these short term measurements during the melt season with surface velocities computed from feature tracking of satellite images shows a high seasonal variability of the ice motion we have shown that this variability is up to 100 of the annual mean velocity on the basis of these investigations the mass fluxes at the concordia cross section have been quantified this approach can now be used together with the ablation calculations to reconstruct the variability of glacier extent and volume in the past using available climate data from the central karakoram from the comparison of historical measurements and photographs it is shown that the snout of baltoro glacier is oscillating back and forth a couple of hundred metres otherwise it seems not to react with the same magnitude as other glaciers to the climatic change elevation changes at concordia are a few tens of metres at the most

depositional bias and environmental change important factors in sequence stratigraphy abstract differences among depositional systems here called depositional bias strongly influence sequence patterns siliciclastics and shallow water carbonates for instance shed most of their sediment during opposite phases of a sea level cycle lowstand shedding and highstand shedding respectively furthermore the two systems generate their own system specific relief on the sea floor disperse their sediment load along different avenues and differ in the way they are deactivated reefs and carbonate platforms can be drowned whereas siliciclastic deposition can be shut off and renewed at any depth as a consequence of these differences pronounced unconformities drowning unconformities develop where carbonate platforms are terminated and buried by siliciclastics the siliciclastic to carbonate transition tends to be more gradual drowned platforms and drowning unconformities appeared world wide in great abundance in the miocene cretaceous valanginian turonian jurassic toarcian and devonian frasnian famennian examples of drowning unconformities interpreted as sequence boundaries include those of the early cretaceous platforms off new jersey and off morocco the mid cretaceous unconformity in the gulf of mexico and miocene unconformities on top of reefs in the far east the eustatic cycles postulated from sequence stratigraphy are a very unlikely cause for the mass drownings of reefs and platforms either the rates of rise are an order of magnitude lower than the growth potential of platforms or cycle amplitudes are too small or the cycles are too short and subsidence too slow to remove platforms permanently from the photic zone the critical element in the mass drowning seems to be environmental stress that reduces the growth potential of carbonate systems thus drowning unconformities demonstrate the importance of environmental change as a control on sequence development other examples of dominantly environment controlled sequences include slope deposits shaped by shifting currents e g florida and blake plateau and basin fills that were controlled by changes in sediment input related to tectonic alteration of the drainage in the hinterland e g gulf of mexico environmental change must be considered as a third independent factor that competes with eustatic and tectonically driven regional changes of sea level for control of sequences the definition of sequences and sequence boundaries should be broad enough to include the possibility of non sea level controls

molecular isotopic evidence of environmental and ecological changes across the cenomanian turonian boundary in the levant platform of central jordan abstract we evaluated the structure of planktonic communities and paleoenvironmental conditions throughout the cenomanian turonian oceanic anoxic event oae2 by studying bulk geochemical properties and the molecular isotopic composition of source specific hydrocarbons from organic rich sediments deposited in an intrashelf basin at the levant platform central jordan high concentrations of desmethyl and 4 methylsteranes as well as dinosteranes indicate that marine algae including dinoflagellates were the main primary producing organisms the presence of 2 methylhopanes and 13 c enriched hopanes in addition to isotopically enriched aryl isoprenoids evidenced the contribution of cyanobacteria and green sulfur bacteria respectively additionally variable but fairly low 15 n values during oae2 suggest the occurrence of diazotrophy as a likely important process fueling primary production during oae2 in this stratified anoxic continental platform variations in the relative contribution of biomarkers revealed changes in planktonic communities associated with sea level change and water column stratification oae2 was characterized by strong stratification anoxic bottom waters and a deep chemocline as evidenced by high gammacerane and homohopane indices and the absence of photic zone euxinia pze markers respectively however the presence of isorenieratane and its derivatives in post oae black shales points to a shoaling of the chemocline and to pze this interval was also characterized by an exceptionally high abundance of chlorophyll derived pristane and phytane up to 2 mg g 1 toc likely as a result of highly enhanced primary production and organic matter preservation remarkably this high productivity event co occurs with an exceptionally high abundance of calcispheres reported elsewhere to be part of a global bio event

geochemistry of 1 9 ga morb and oib like basalts from the amisk collage flin flon belt canada evidence for an intra oceanic origin subaqueously erupted basalts that occur in kilometre scale allochthons within the 1 9 ga flin flon belt canada appear to have been generated at oceanic ridges and possibly oceanic plateaus remote from archean cratons the ocean floor basalts fall into two categories 1 n type resembling n morbs and mariana type back arc basin basalts depleted to flat ree patterns high zrnb variable thnb and initial nd 3 3 to 5 4 2 e type resembling transitional and plume morbs slightly enriched ree patterns lower zrnb initial nd 3 1 to 4 5 in the largest and best studied allochthon the elbow athapapuskow assemblage mixing between depleted n morb and enriched oib sources or melts coupled with variable addition of a subduction lile component can explain the chemical variations in the basalts zircon u pb dates of 1904 ma for a syn volcanic diabase sill and 1901 6 5 ma for a gabbro peridotite cumulate complex demonstrate that crystallization of the ocean floor basalts overlapped with in part eruption of the tectonically juxtaposed 1 90 1 88 ga arc volcanic rocks the elbow athapapuskow allochthon is interpreted as back arc basin crust that developed simultaneously with flin flon arc magmatism subaerially erupted basalts that chemically resemble tholeiitic oibs 8 14 mgo relative hree depletion initial nd 2 2 to 3 4 occur in tectonic contact with the elbow athapapuskow assemblage the oibs may have been generated by deeper garnet residue melting of enriched mantle tapped during extension in the elbow athapapuskow back arc basin and were possibly erupted onto a remnant arc deeper mantle melting is also indicated by the presence of the lree enriched oceanic plateau like basalts of the sandy bay assemblage the back arc 01b and plateau volcanic assemblages were jux taposed against ca 1 9 ga arc assemblages in a philippines like intraoceanic accretionary complex by 1 87 ga

middle and late cenomanian oceanic anoxic events in shallow and deeper shelf environments of western morocco the response of shallow water sequences to oceanic anoxic event 2 and mid cenomanian events 1a and 1b was investigated along the west african margin of morocco north of agadir azazoul and correlated with the deep water sequence of the tarfaya basin mohammed beach based on biostratigraphy mineralogy phosphorus and stable isotopes in the deeper mohammed beach section results show double peaks in 13corg for mid cenomanian events 1a and 1b rotalipora reicheli biozone lower cc10a biozone the characteristic oceanic anoxic event 2 13c excursion rotalipora cushmani extinction top of cc10a biozone and laminated anoxic black shale in the shallow environment north of agadir a fluctuating sea level associated with dysoxic brackish and mesotrophic conditions prevailed during the middle to late cenomanian as indicated by oyster biostromes nannofossils planktonic and benthonic foraminiferal assemblages anoxic conditions characteristic of oceanic anoxic event 2 for example laminated black shales did not reach into shallow water environments until the maximum transgression of the early turonian climate conditions decoupled along the western margin of morocco between mid cenomanian event 1b and the cenomanian turonian boundary as also observed in eastern tethys north of agadir alternating humid and dry seasonal conditions prevailed whereas in the tarfaya basin the climate was dry and seasonal this climatic decoupling can be attributed to variations in the intertropical convergence zone and in the intensity of the north east trade winds in tropical areas

slight mass gain of karakoram glaciers in the early twenty first century the mass balance of hindu kush karakoram himalaya glaciers has been debated partly because of a severe lack of observations from the region an analysis of the regional mass balance of karakoram glaciers by comparison of digital elevation models from 1999 to 2008 reveals a small glacier mass gain in the area

cenomanian turonian carbonate platform deposits in west central jordan we studied upper albian to turonian shallow marine shelf deposits ajlun group of west central jordan along a nne ssw running transect the carbonate dominated succession includes few siliciclastic intercalations claystones and shales and can be subdivided into five formations the naur fuheis and hummar formations of upper albian to upper cenomanian age represent shallow subtidal to supratidal platform environments the uppermost cenomanian to middle turonian shueib formation includes deeper water deposits of the inner mid shelf and locally toc rich black shales shallow marine platform environments once again dominate the wadi as sir formation middle upper turonian a new multibiostratigraphic framework is based on ammonites mainly of the middle cenomanian rhotomagense zone to the middle turonian woollgari zone and calcareous nannofossils biozones cc 9 cc 11 supplemented by benthic and planktonic foraminifers and ostracods it forms the base of a sequence stratigraphic subdivision containing eight sedimentary sequences s1 s8 which are separated by four cenomanian sequence boundaries cejo1 cejo4 and three turonian sequence boundaries tujo1 tujo3 this scheme allows the correlation of the platform succession from distal to proximal shelf areas in contrast to previous correlations using lithologic units furthermore comparisons between the platform successions and sequence patterns of west central jordan and those from neighbouring areas allow to differentiate local regional and global controlling factors of platform development within the study area

cenomanian turonian stable isotope signatures and depositional sequences in northeast egypt and central jordan abstract lithostratigraphic biostratigraphic and microfacies studies of two cenomanian turonian shallow marine siliciclastic carbonate successions at gebel ekma plateau southwestern sinai egypt and wadi karak section central jordan are calibrated with 13c profiles to reveal relative sea level changes within a sequence stratigraphic framework the study provides significantly enhanced stratigraphic resolution and key sections for regional correlation lithofacies are dominated by well developed peritidal to subtidal facies associations indicating deposition in a rimmed carbonate shelf setting biostratigraphic analysis indicates the presence of 6 ammonite zones 3 calcareous nannofossil zones and 3 planktonic foraminiferal zones within the cenomanian to turonian succession six third order depositional sequences bounded by correlatable sequence boundaries can be traced across the african arabian platform comparison with 13c records in deeper water pelagic sequences help to improve the resolution of the boundaries of each depositional sequence recognition of time gaps at the sequence boundaries on the platform recorded in different parts of african arabian platform is attributed to local tectonic activity associated with the change from passive to active margins which are overprinted by the global eustatic signature

heterogeneous influence of glacier morphology on the mass balance variability in high mountain asia we investigate the control of the morphological variables on the 2000 2016 glacier wide mass balances of 6 470 individual glaciers of high mountain asia we separate the data set into 12 regions assumed to be climatically homogeneous we find that the slope of the glacier tongue mean glacier elevation percentage of supraglacial debris cover and avalanche contributing area all together explain a maximum of 48 and a minimum of 8 of the glacier wide mass balance variability within a given region the best predictors of the glacier wide mass balance are the slope of the glacier tongue and the mean glacier elevation for most regions with the notable exception of the inner tibetan plateau glacier wide mass balances do not differ significantly between debris free and debris covered glaciers in 7 of the 12 regions analyzed lake terminating glaciers have more negative mass balances than the regional averages the influence of lakes being stronger on small glaciers than on large glaciers

sequence architecture and carbonate platform configuration late cenomanian santonian sinai egypt relative sea level changes on the mixed carbonate siliciclastic platform of sinai are manifested in shifts of distinct facies belts deep water facies highenergy subtidal shallow subtidal lagoon shallow shoreface siliciclastics supratidal and are interpreted in terms of sequence stratigraphy eight sedimentary sequences are recognized for the upper cenomanian to santonian their correlation along a north south transect reveals distinct changes in lithofacies and progradation retrogradation patterns within the individual systems tracts the number and stratigraphy of the sequence boundaries of sinai correlate well with those from adjacent areas patterns of increased subsidence are documented for the central sinai basin since the late cenomanian by increased thickness of the stratal packages post cesin 7 hst post tusin 1 lst and hst post tusin 2 lst and are balanced by varying accumulation rates based on new sedimentological and biostratigraphic data large scale palaeogeographic maps and cross sections show the 1 temporal and spatial evolution of the central sinai basin e g its latest cenomanian initial formation lower turonian deep water facies middle turonian to coniacian synsedimentary subsidence 2 drowning of the cenomanian platform coinciding with the latest cenomanian to early turonian relative sea level rise 3 re establishment of the platform in middle late turonian times and 4 a coniacian basin and swell morphology

ice velocity and climate variations for baltoro glacier pakistan quincey dj copland l mayer c bishop m luckman a belo m 2009 ice velocity and climate variations for the baltoro glacier pakistan journal of glaciology 55 194 1061 1071 sponsorship rcuk us national science foundation us national geographic society natural sciences and engineering research council of canada canadian foundation for innovation ontario research fund university of ottawa

deciphering the contrasting climatic trends between the central himalaya and karakoram with 36 years of wrf simulations glaciers over the central himalaya have retreated at particularly rapid rates in recent decades while glacier mass in the karakoram appears stable to address the meteorological factors associated with this contrast 36 years of climate forecast system reanalyses cfsr are dynamically downscaled from 1979 to 2015 with the weather research and forecasting wrf model over high mountain asia at convection permitting grid spacing 6 7 km in all seasons cfsr shows an anti cyclonic warming trend over the majority of high mountain asia but distinctive differences are observed between the central himalaya and karakoram in winter and summer in winter and summer the central himalaya has been under the influence of an anti cyclonic trend which in summer the downscaling shows has reduced cloud cover leading to significant warming and reduced snowfall in recent years contrastingly the karakoram has been near the boundary between large scale cyclonic and anti cyclonic trends and has not experienced significant snowfall or temperature changes in winter or summer despite significant trends in summer of increasing cloud cover and decreasing shortwave radiation this downscaling does not identify any trends over glaciers in closer neighboring regions to the karakoram e g hindu kush and the western himalaya where glaciers have retreated as over the central himalaya indicating that there are other factors driving glacier mass balance that this downscaling is unable to capture while this study does not fully explain the karakoram anomaly the identified trends detail important meteorological contributions to the observed differences between central himalaya and karakoram glacier evolution in recent decades

biostratigraphy palaeoecology and palaeogeography of the middle cenomanian early turonian levant platform in central jordan based on ostracods

irrigation as a potential driver for anomalous glacier behavior in high mountain asia many glaciers in the northwest of high mountain asia hma show an almost zero or positive mass balance despite the global trend of melting glaciers this phenomenon is often referred to as the karakoram anomaly although strongest positive mass balances can be found in the kunlun shan mountain range northeast of the karakoram using a regional climate model in combination with a moisture tracking model we show that the increase in irrigation intensity in the lowlands surrounding hma particularly in the tarim basin can locally counter the effects of global warming on glaciers in kunlun shan and parts of pamir and northern tibet through an increase in summer snowfall and decrease in net radiance irrigation can thus affect the regional climate in a way that favors glacier growth and future projections of glacier melt which may impact millions of inhabitants surrounding hma will need to take into account predicted changes in irrigation intensity