integrated hazard assessment of cirenmaco glacial lake in zhangzangbo valley central himalayas abstract glacial lake outburst floods glofs have recently become one of the primary natural hazards in the himalayas there is therefore an urgent need to assess glof hazards in the region cirenmaco a moraine dammed lake located in the upstream portion of zhangzangbo valley central himalayas has received public attention after its damaging 1981 outburst flood here by combining remote sensing methods bathymetric survey and 2d hydraulic modeling we assessed the hazard posed by cirenmaco in its current status inter annual variation of cirenmaco lake area indicates a rapid lake expansion from 0 10 0 08 km2 in 1988 to 0 39 0 04 km2 in 2013 bathymetric survey shows the maximum water depth of the lake in 2012 was 115 2 m and the lake volume was calculated to be 1 8 107 m3 field geomorphic analysis shows that cirenmaco glacial lake is prone to glofs as mass movements and ice and snow avalanches can impact the lake and the melting of the dead ice in the moraine can lower the dam level hec ras 2d model was then used to simulate moraine dam failure of the cirenmaco and assess glof impacts downstream reconstruction of cirenmaco 1981 glof shows that hec ras can produce reasonable flood extent and water depth thus demonstrate its ability to effectively model complex glofs glof modeling results presented can be used as a basis for the implementation of disaster prevention and mitigation measures as a case study this work shows how we can integrate different methods to glof hazard assessment

ice moraine and landslide dams in mountainous terrain we review recent work on ice moraine and landslide dams in mountainous terrain thus complementing several comprehensive summaries on glacier dams in intracontinental and arctic areas of low relief we discuss the roles of tectonic and climatic forcing on ice moraine and landslide dam formation and sudden drainage and focus on similarities and differences between their geomorphic impacts on confined valleys drained by steep bedrock and gravel bed rivers despite numerous reported failures of natural dams in mountain belts throughout the world their relevance to long term dynamics of mountain rivers remains poorly quantified all types of dams exert local base level controls thus trapping incoming sediment and inhibiting fluvial bedrock incision pervasive geomorphic and sedimentary evidence of outburst events is preserved even in areas of high erosion rates suggesting that sudden dam failures are characterized by processes of catastrophic valley floor aggradation active channel widening and downstream dispersion of sediment during which little bedrock erosion seems to be achieved we find that in the absence of direct evidence of former dams a number of similarities among the geomorphic and sedimentologic characteristics of catastrophic outburst flows may give rise to ambiguous inferences on the dam forming process this is especially the case for tectonically active mountain belts where there is ample and comparable potential for the formation and failure of ice moraine landslide and polygenetic dams concomitant with climatic oscillations or earthquake disturbance hence the palaeoclimatic implications of erroneously inferring the cause of dam formation may be significant we recommend that future research on natural dams in mountainous terrain addresses a climate and earthquake controlled systematics in the pattern of formation and failure b quantification of response of mountain rivers to catastrophic outburst events and their concomitant process sequences c elaboration of a comprehensive classification of natural dams in mountainous terrain with special attention to polygenetic dams d physical based modelling of dam formation failure and routing of water and sediment outbursts and e quantitative controls on the contribution of natural dams to sediment budgets in mountainous terrain

a review of catastrophic drainage of moraine dammed lakes in british columbia abstract moraine dammed lakes are common in the high mountains of british columbia most of these lakes formed when valley and cirque glaciers retreated from advanced positions achieved during the little ice age many moraine dams in british columbia are susceptible to failure because they are steep sided have relatively low width to height ratios comprise loose poorly sorted sediment and may contain ice cores or interstitial ice in addition the lakes commonly are bordered by steep slopes that are prone to snow and ice avalanches and rockfalls moraine dams generally fail by overtopping and incision the triggering event may be a heavy rainstorm or an avalanche or rockfall that generates waves that overtop the dam the dam can also be overtopped by an influx of water caused by sudden drainage of an upstream ice dammed lake jokulhlaup melting of moraine ice cores and piping are other possible failure mechanisms failures of moraine dams in british columbia produce destructive floods orders of magnitude larger than normal streamflows most outburst floods are characterized by an exponential increase in discharge followed by an abrupt drop to background levels when the water supply is exhausted peak discharges are controlled by dam characteristics the volume of water in the reservoir failure mechanisms and downstream topography and sediment availability for the same potential energy at the dam site floods from moraine dammed lakes have higher peak discharges than floods from glacier dammed lakes the floodwaters may mobilize large amounts of sediment as they travel down steep valleys producing highly mobile debris flows such flows have larger discharges and greater destructive impact than the floods from which they form moraine dam failures in british columbia and elsewhere are most frequent following extended periods of cool climate when large lateral and end moraines are built a period of protracted warming is required to trap lakes behind moraines and create conditions that lead to dam failure this sequence of events occurred only a few times during the holocene epoch most notably during the last several centuries glaciers built large moraines during the little ice age mainly during the 1700s and 1800s and lakes formed behind these moraines when climate warmed in the 1900s twentieth century climate warming is also responsible for recent moraine dam failures in mountains throughout the world warming from the late 1800s until about 1940 and again from 1965 to today destabilized moraine dams with interstitial or core ice the warming also forced glaciers to retreat prompting ice avalanches landslides and jokulhlaups that have destroyed some moraine dams

accelerated hydration of the earth s deep crust induced by stress perturbations the metamorphic cycle associated with the formation of mountain belts produces a lower crust containing little or no free fluid1 2 the introduction of external fluids to dry and impermeable volumes of the earth s crust is thus a prerequisite for the retrogressive metamorphism later observed in such regimes such metamorphism can cause significant changes in the crust s physical properties including its density rheology and elastic properties3 4 on a large scale the introduction of fluids requires the presence of high permeability channels such as faults or fractures which are the result of external tectonic stresses but extensive interaction between externally derived fluids and the fractured rock requires efficient mass transport away from the initial fractures into the rock itself and this transport often occurs over distances much longer than expected from grain boundary diffusion here we present both field observations and a simple network model that demonstrate how the transport of fluids into initially dry rock can be accelerated by perturbations in the local stress field caused by reactions with fluids we also show that the morphology of reaction fronts separating dry from wet rocks depends on the anisotropy of the external stress field

a gabbro to eclogite transition on flemsoy sunnmore western norway the migmatitic gneisses on the nordoyane islands western norway enclose abundant inclusions of coronitic gabbros and different types of country rock eclogites gabbros on flemsoy show a prograde step wise transition to eclogite via a transitional stage in which garnet and orthopyroxene form coronas between igneous olivine and sodic plagioclase relics after igneous plagioclase cumulates eclogitization proceeds by a complex set of continuous and discontinuous reactions opx and spinel form as transient phases but are consumed in various omphacite forming reactions during eclogite recrystallization relict igneous clinopyroxene shows a continuous increase in jd content while garnet becomes less calcic and more homogeneous from the corona stage to recrystallized eclogite the reactions are strongly diffusion controlled and have been enhanced locally by oxidation and the presence of a fluid phase and deformation while low strain areas of the gabbros remained coronitic whole rock chemistry mineral parageneses and calculated p t conditions are similar for the gabbroeclogites and two types of country rock eclogites some of the layered country rock eclogites appear to have been derived from the coronite bodies p estimates are in the order 15 20 kbar while kgarcpxd values suggest maximum t values of 750 60 c for the eclogite metamorphism in the area

characterization of transport and water retention properties of damaged callovo oxfordian claystone in the context of the underground storage of radioactive waste the aim of this experimental study is to characterize the effect of damage on transport and water retention properties of callovo oxfordian cox argillite the originality of the study is to simultaneously investigate the pore size distribution water retention the dry effective and relative gas permeability and the gas breakthrough pressure gbp of damaged cox argillite these different properties are all relevant to characterizing the fluid transport ability of cox argillite results show that the damage has a significant impact on the properties of the cox argillite it induces a decrease in its water retention capacity and gbp and it increases its gas permeability and apparent porosity available to water owing to the creation of micro cracks another objective is to show which of these properties is the most suitable to detect early damage states in cox argillite with a potential use being to identify them in situ gbp appears to be the best detector of damage because of its sensitivity to damage even under high confinement pressures gas permeability could be a good indicator of damage as it increases significantly one or several orders of magnitude after the damage finally the water permeability curve is a poor indicator of cox argillite damage

evolution of caledonian deformation fabrics under eclogite and amphibolite facies at vardalsneset western gneiss region norway the vardalsneset eclogite situated in the western gneiss region sw norway is a well preserved tectonite giving information about the deformation regimes active in the lower crust during crustal thickening and subsequent exhumation the eclogite constitutes layers and lenses variably retrograded to amphibolite and is composed of garnet and omphacite with varying amounts of barroisite actinolite clinozoisite kyanite quartz paragonite phengite and rutile the rocks record a five stage evolution connected to caledonian burial and subsequent exhumation 1 a prograde evolution through amphibolite facies t 490 63 c is inferred from garnet cores with amphibole inclusions and bell shaped mn profile 2 formation of l s tectonite eclogite t 680 20 c p 16 2 kbar related to the subduction of conti nental crust during the caledonian orogeny lack of asymmetrical fabrics and orientation of eclogite facies extensional veins indicate that the deformation regime during formation of the l s fabric was coaxial 3 formation of sub horizontal eclogite facies foliation in which the finite stretching direction had changed by approximately 90 disruption of eclogite lenses and layers between symmetric shear zones characterizes the dominantly coaxial deformation regime of stage 3 locally occurring mylonitic eclogites t 690 20 c p 15 1 5 kbar with top w kinematics may indicate however that non coaxial deformation was also active at eclogite facies conditions 4 development of a widespread regional amphibolite facies foliation t 564 44 c p 10 3 8 1 kbar quartz veins and development of conju gate shear zones indicate that coaxial vertical shortening and sub horizontal stretching were active during exhumation from eclogite to amphibolite facies conditions 5 amphibolite facies mylonites mainly formed under non coaxial top w movement are related to large scale movement on the extensional detachments active during the late orogenic extension of the caledonides the structural and metamorphic evolution of the vardalsneset eclogite and related areas support the exhumation model including an extensional detachment in the upper crust and overall coaxial deformation in the lower crust

under stress permeability determination of the meuse haute marne mudstone abstract in the underground waste isolation projects such as the andra one in the site of bure the transport properties of the surrounding rock mass is of fundamental importance to measure very low permeability we use the modified version of the pulse test proposed by hsieh et al hsieh p a tracy j v neuzil c e bredehoeft j d silliman s e 1981 a transient laboratory method for determining the hydraulic properties of tight rocks i theory int j rock mech min sci geomech abstr vol 18 pp 245 252 which enables the intrinsic permeability k and the specific storage coefficient s s of rocks such as mudstone to be characterized in this paper the special effort performed on the laboratory apparatus design to ensure a good sensitivity of the rock response with respect to both parameters k and s s is presented in addition two parameters identification procedures are proposed the graphical method given by hsieh et al hsieh p a tracy j v neuzil c e bredehoeft j d silliman s e 1981 a transient laboratory method for determining the hydraulic properties of tight rocks i theory int j rock mech min sci geomech abstr vol 18 pp 245 252 and a parameter identification based on the solution of an inverse problem the efficiency of the apparatus design and the parameters identification procedures is then demonstrated though some pulse tests performed on the meuse haute marne mudstone

remote sensing based assessment of hazards from glacier lake outbursts a case study in the swiss alps glacier lakes are a common phenomenon in high mountain areas outbursts from glacier lakes have repeatedly caused the loss of human lives as well as severe damage to local infrastructure in several high mountain ranges around the world a grave uncertainty about the hazard potential of glacier lakes still exists especially with respect to the effects of accelerating rates of glacier retreat as a consequence of atmospheric warming area wide detection and modeling of glacier lake hazard potentials is therefore a major challenge in this study an approach integrating three scale levels allows for the progressive focus on critical glacier lakes remote sensing methods for application in glacier lake hazard assessment are presented and include channel indexing data fusion and change detection each method matches the requirements of a certain scale level for estimating potential disaster amplitudes assessments must be made of maximum discharge and runout distance of outbursts floods and debris flows existing empirical relations are evaluated and complementary ones as derived from available data are proposed tests with observations from a recent outburst event from a moraine dammed lake in the swiss alps show the basic applicability of the proposed techniques and the usefulness of empirical relations for first hazard assessments in particular the observed runout distance of the debris flow resulting from the outburst does not exceed the empirically estimated maximum runout distance a list of decision criteria and related remote sensing techniques are discussed in conclusion such a list is an essential tool for evaluating the hazard potential of a lake a systematic application of remote sensing based methods for glacier lake hazard assessment is recommended

progressive eclogitization under fluid present conditions of pre alpine mafic granulites in the austroalpine mt emilius klippe italian western alps metabasites from the austroalpine mt emilius klippe preserve different stages of the evolution from pre alpine granulite to alpine eclogite facies assemblages the pre alpine protolith includes layered garnet i clinopyroxene i plagioclase hornblende granulites and gabbros the eclogitic paragenesis comprises garnet ii clinopyroxene ii epidote ca amphibole chlorite eclogitic deformation is composite and involves two main episodes d1a d1b d1a produces a layer parallel foliation and incomplete transformation of granulites and is concluded by an episode of brittle deformation leading to the formation of eclogitic veins d1b gives rise to widespread s l tectonites and mylonites the eclogitic veins and surrounding haloes enriched in fluids during veining control the nucleation of d1b shear zones deformation is accomplished through ductile flow of reaction weakened plagioclase and hornblende sites and cataclasis of garnet i and clinopyroxene i both meso and microscale observations indicate that fluids play a primary role during eclogitization in both enhancing deformation and the kinetics of metamorphic reactions fluids influence plastic flow rates in matrix aggregates and promote fracturing of hard minerals the extent of metamorphic re equilibration is closely related to the density of the fluid pathways

structural development and petrofabrics of eclogite facies shear zones bergen arcs western norway implications for deep crustal deformational processes caledonian eclogite facies shear zones developed from grenvillian garnet granulite facies anorthosites and gabbros in the bergen arcs of western norway allow direct investigation of the relations between macroscopic structures and crystallographic preferred orientation cpo in lower continental crust field relations on the island of holsnoy show that the eclogites formed locally from granulite facies rocks by progressive development of 1 eclogite adjacent to fractures 2 eclogite in discrete shear zones 2 m thick 3 eclogite breccia consisting of 80 well foliated eclogite that wraps around rotated granulite blocks and 4 anastomosing subparallel eclogite facies shear zones 30 100 m thick continuous over distances 1 km within the granulite terrane these shear zones deformed under eclogite facies conditions at an estimated temperature of 670 50 c and a minimum pressure of 1460 mpa which corresponds to depths of 55 km in the continental crust detailed investigation of the major shear zones shows the development of a strong foliation defined by the shape preferred orientation of omphacite and by alternating segregations of omphacite garnet rich and kyanite zoisite rich layers a consistent lineation throughout the shear zones is defined by elongate aggregates of garnet and omphacite the cpo of omphacite determined from five axis universal stage measurements shows a strong b axis maximum normal to foliation and a c axis girdle within the foliation plane with weak maxima parallel to the lineation direction these patterns are consistent with deformation of omphacite by slip parallel to 001 and suggest glide along 010 the lineation and cpo data reveal a consistent sense of shear zone movement although the displacement was small localized faulting of high grade rocks accompanied by fluid infiltration can be an important mode of failure in the lower continental crust field relations show that granulite facies rocks can exist in a metastable state under eclogite facies conditions and imply that the lower crust can host differing metamorphic facies at the same depth deformation of granulite and partial conversion to eclogite such as is exposed on holsnoy island may be an orogenic scale process in the lowermost crust of collisional orogens

methods for assessing regional glacial lake variation and hazard in the southeastern tibetan plateau a case study from the boshula mountain range china glaciers on the tibetan plateau are undergoing an accelerating retreat under climatic warming with the immediate result of glacial lake outburst floods glofs becoming increasingly frequent glacial lakes in the southeast of the tibetan plateau are densely distributed due to the difficulties associated with field investigations of glacial lakes including remote locations and harsh weather conditions methods which combine remote sensing geographic information systems and hydrodynamic modeling hec ras with field investigation were developed to assess regional glacial lake variation and hazard the methods can be divided into three levels at the first level multi temporal satellite images were used to 1 study the variation of glacial lakes for the whole region during recent decades as well as 2 qualitatively identify potentially dangerous glacial lakes pdgls the second level is an in depth evaluation of the degree of danger for selected pdgls by ground based surveys and then verification of the first level results at the third level the one dimensional 1d hydrodynamic model hec ras was used to simulate the inundation characteristics of hypothetical outburst of pdgls the three levels downscale from the whole study area to individual pdgls and thus assess the hazard of glacial lakes progressively the methods were then applied to a region of southeastern tibet the boshula mountain range to analyze the variation of glacial lakes and assess potential hazards posed by glofs since these methods employ easily accessible data and instruments the application in other regions is promising

coesite in clinopyroxene in the caledonides and its implications for geodynamics coesite is reported for the first time from the caledonide orogen it occurs as inclusions in clinopyroxene in the dolomite eclogite at grytting norway and provides valuable new evidence to support the hypothesis of extremely high pressure 30 kbar in certain norwegian eclogites this finding has implications for the geodynamics and kinetics of the concepts of microscale intracrystalline tectonic overpressure and of macroscale local or regional tectonic overpressure and for the hypotheses of subduction and obduction involving a more than 100km vertical component of transport

recent glacier and glacial lake changes and their interactions in the bugyai kangri southeast tibet glaciers in the bugyai kangri are located in a transition zone from southeast tibet where monsoonal temperate glaciers dominate to inner tibet where continental glaciers dominate here we analyze glacier and glacial lake changes in this region using multi year inventories based on landsat images from 1981 2013 results show that the total area of 141 glaciers in the region decreased by 30 44 0 89 km 2 from 198 35 9 54km 2 1980s to 167 93 4 52 km 2 2010s the annual area shrinkage rate 0 48 a 1 is lower than that reported for southeastern tibet but higher than that of inner tibet both the number and total area of glacial lakes increased between 1981 and 2013 among all lakes proglacial lakes contribute most similar to 81 to the expansion the total area of ten proglacial lakes increased by 150 3 13 17 and of these ten lakes the four that expanded most sharply showed increased calving at their upper margins resulting in more rapid retreat of lake terminating glaciers than land terminating glaciers owing to rapid calving several lakes may undergo further growth in the near future increasing the potential risk of glacial lake outburst floods

volume calculation and analysis of the changes in moraine dammed lakes in the north himalaya a case study of longbasaba lake glacial lake outburst flood hazards in the himalayan region have received considerable attention in recent years accurate volume estimation for glacial lakes is important for calculating outburst flood peak discharge and simulating flood evolution longbasaba lake a potentially dangerous moraine dammed lake is located on the north side of the himalaya its depth was surveyed using the syqwest hydrobox high resolution echo sounder and 6916 measurements were collected in september 2009 the maximum and average depths of the lake were 102 2 and 48 2 m respectively the morphology of the lake basin was modeled by constructing a triangulated irregular network and the lake was found to have a storage capacity of 0 064 0 002 km 3 multi source remote sensing images from landsat mss landsat tm etm and terra aster and a topographic map were digitized to delineate the outlines of the lake between 1977 and 2009 the results indicate that the length and area of the lake have increased during the past 32 years with a drastic expansion occurring since 2000 based on volume and area data of longbasaba lake in different periods we deduced an empirical equation of the lake volume area relationship that can be used to calculate the storage capacity of similar moraine dammed lakes in the himalayan region

changes in glacial lakes and glaciers of post 1986 in the poiqu river basin nyalam xizang tibet glacial lakes and glaciers are sensitive indicators of recent climate change in the poiqu river basin of southern tibet 60 100 km nw of mt everest landsat imagery defines post 1986 changes in the size and distribution of both glacial lakes and glaciers total area of glaciers in the 229 km2 drainage area has decreased by 20 the number of glacial lakes with areas in excess of 0 020 km2 has increased by 11 and the total area of glacial lakes has increased by 47 the areas of typical large glacial lakes of the area galongco gangxico and cirenmaco have increased by 104 118 and 156 respectively and these increases are confirmed by field investigations comparing the 1986 data the area of glaciers in the basin headwaters has decreased by 46 18 km2 to a present total area of 183 12 km2 an annual rate of change of 3 30 km2 year trends indicate that the total area of glaciers will continue to decrease and that both the numbers and areas of glacial lakes will continue to increase accompanying these trends will be an increased risk of debris flows formed by entrainment of sediment in glacial outburst floods and in surges from both failure and avalanche and landslide induced overtopping of moraine dams based on both the local and world wide history of catastrophes from flows of these origins disaster mitigation must be planned and appropriate engineering countermeasures put in place as soon as possible

interaction between fluid flow fracturing and mineral growth during eclogitization an example from the sunnfjord area western gneiss region norway in sunnfjord western gneiss region of south norway a proterozoic layered gabbro complex displays various degrees of transformation to eclogite in the unreacted parts layering in the gabbro is defined by modal variations of plagioclase olivine pyroxenes and minor fe ti oxide and spinel coronitic and foliated eclogite formed from the gabbro by hydration reactions at t 510 620 c causing a volume decrease of c 13 in the coronitic eclogite the mafic magmatic phases are replaced by aggregates of omphacite barroisite tremolite talc and rutile whereas the plagioclase domains are pseudomorphed by omphacite barroisite clinozoisite kyanite paragonite and garnet the felsic and mafic domains are separated by a garnet rim up to 5 mm thick garnet was also formed along dilational veins connecting and radiating out of coronas including the same eclogite facies minerals in addition microfractures filled by amphibole and omphacite cut through the corona and vein garnet oriented perpendicular to the garnet layering the transformation of dry gabbro to eclogite with hydrous minerals requires supply of water the timing of metamorphic reactions is therefore dependent on the timing of fluid introduction the inclusion pattern of garnet in the holt tyssedalsvatnet metagabbro complex indicates that transformation started under eclogite facies conditions brittle deformation in form of fractures allowing infiltration of fluids and mobilisation of elements is shown to be the most important process initiating transformation brittle deformation is thereby active in deep crustal levels corresponding to eclogite facies conditions fracturing is interpreted as having been caused by a combination of high fluid pressure volume changes during mineral transformations and external stresses ductile deformation started after the initial metamorphic transformation garnet chemistry and zoning pattern are controlled by the chemistry of the growth place the fluid influx and element supply abrupt chemical variations across corona garnet may have been formed by an interaction between rapid growth and transport along microfractures between plagioclase and mafic domain the metamorphic transition proceeded rapidly the transformation of the deep crust to eclogite can be viewed as a dynamic process where the volume changes result in fracturing and these fractures funnelling fluid and element enhancing mineral reaction the densification causes further fracturing indicating that the process is self driven provided that fluid is available

geomorphological and stratigraphic evidence along the northeastern u s margin for laurentide glacial lake outburst floods during the mis 2 deglaciation

the significance of grain scale stresses in the kinetics of metamorphism during metamorphism phases grow and dissolve dominantly along grain boundaries bulk diffusion models for the development of metamorphic textures often assume that diffusion is homogeneous in regions of each phase rather than being localised along phase boundaries under isotropic stress chemical potentials of components involved in reactions are likely to be buffered along grain boundaries between phases thus inhibiting diffusion and growth motive forces must exist which overcome this and it is proposed here that local heterogeneous stresses will be important a mathematical theory for stress controlled growth is derived this theory predicts that the growth rates of two phases along their mutual interface will be linked in a quantifiable way it forms a basis for considering the important effects of stresses induced by local volumetric changes during metamorphism and it provides a link between these effects and those related to pressure solution in deforming rocks

recent climatic change and catastrophic geomorphic processes in mountain environments climatic warming during the last 100 150 years has resulted in a significant glacier ice loss from mountainous areas of the world certain natural processes which pose hazards to people and development in these areas have accelerated as a result of this recent deglaciation these include glacier avalanches landslides and slope instability caused by glacier debuttressing and outburst floods from moraine and glacier dammed lakes in addition changes in sediment and water supply induced by climatic warming and glacier retreat have altered channel and floodplain patterns of rivers draining high mountain ranges the perturbation of natural processes operating in mountain environments caused by recent climatic warming ranges from tens of decades for moraine dam failures to hundreds of years or more for landslides the recognition that climatic change as modest as that of the last century can perturb natural alpine processes has important implications for hazard assessment and future development in mountains even so these effects are probably at least an order of magnitude smaller than those associated with late pleistocene deglaciation ca 15 000 to 10 000 years ago

variations of glacial lakes and glaciers in the boshula mountain range southeast tibet from the 1970s to 2009 catastrophic floods originating from glacial lake outbursts have recently become one of the primary natural hazards in the southeastern tibetan plateau here we report observations of glacial lake expansions and glacier recessions in the boshula mountain range southeast tibet derived from multitemporal remote sensing images and digital elevation models during the period from the 1970s to 2009 the area of glacial lakes has expanded from 9 24 0 1 km 2 in the 1970s to 10 96 0 1 km 2 in 2009 specifically the area of moraine dammed lakes has increased by 26 8 from the 1970s to 2009 the glacierized area in the boshula mountain range shrank by 12 7 21 2 km 2 increasing mean summer air temperature was the main cause for the glacier recession and lake expansion from the 1970s to 2001 while the combination of increased summer temperature and decreased summer precipitation led to accelerated glacier recession after 2001 climate warming and ongoing deglaciation play important roles in the expansion of moraine dammed lakes calling for intensified monitoring to properly address the hazard potential in the study area

glacier recession and glacial lake outburst flood studies in zanskar basin western himalaya abstract glacier recession and formation of glacial lakes along with outburst flood hazards are increasing in response to changing climate in the himalayan region this study describes evolution of dalung and padam glaciers and their associated lakes employing multi temporal datasets of landsat mss tm etm indian remote sensing liss iii google earthtm aster gdem and survey of india topographic maps the dalung glacier dg and lake dl are present in suru river catchment whereas the padam glacier pg and lake pl are present in tsarap river catchment of zanskar basin western himalaya from 1962 to 2015 the dg and pg have shrunk at different rates the dg has shrunk by 2 6 0 56 km2 19 2 4 1 at a rate of 0 05 0 01 km2 a 1 whereas the pg has shrunk by 3 4 0 65 km2 12 7 2 4 at a rate of 0 06 0 01 km2 a 1 the frontal recession was recorded as 1 240 0 02 km 15 7 2 0 at a rate of 20 0 4 m a 1 for dg and 2 690 0 5 m 21 3 2 1 at a rate of 50 7 0 1 m a 1 for pg consequently the proglacial glacial lakes have formed indicating an expansion of 20 3 4 dl and 58 4 5 pl during 1990 2015 using integrated criteria of standard indices for the identification of potentially dangerous glacial lakes pdgls the lakes were found to be vulnerable and have a potential to cause breaching in the coming years in order to provide inputs for the emergency action plan one dimensional mike 11 model was used to generate the peak flood hydrographs at the lake and other vulnerable sites downstream highest peak discharge of 3361 7 m3 s 1 dl and 4210 3 m3 s 1 pl were estimated at the lake sites which has reduced to 1520 9 m3 s 1 and 1722 4 m3 s 1 respectively at the outlet sites the reduced discharge at downstream sites still bears the potential to create dangerous flood hazards

rapid expansion of glacial lakes caused by climate and glacier retreat in the central himalayas glacial lake outburst floods are among the most serious natural hazards in the himalayas such floods are of high scientific and political importance because they exert trans boundary impacts on bordering countries the preparation of an updated inventory of glacial lakes and the analysis of their evolution are an important first step in assessment of hazards from glacial lake outbursts here we report the spatiotemporal developments of the glacial lakes in the poiqu river basin a trans boundary basin in the central himalayas from 1976 to 2010 based on multi temporal landsat images studied glacial lakes are classified as glacier fed lakes and non glacier fed lakes according to their hydrologic connection to glacial watersheds a total of 119 glacial lakes larger than 0 01km 2 with an overall surface area of 20 22km 2 10 8 were mapped in 2010 with glacier fed lakes being predominant in both number 69 58 0 and area 16 22km 2 80 2 we found that lakes connected to glacial watersheds glacier fed lakes significantly expanded 122 1 from 1976 to 2010 whereas lakes not connected to glacial watersheds non glacier fed lakes remained stable 2 8 during the same period this contrast can be attributed to the impact of glaciers retreating glaciers not only supply meltwater to lakes but also leave space for them to expand compared with other regions of the hindu kush himalayas hkh the lake area per glacier area in the poiqu river basin was the highest this observation might be attributed to the different climate regimes and glacier status along the hkh the results presented in this study confirm the significant role of glacier retreat on the evolution of glacial lakes copyright c 2014 john wiley sons ltd

metamorphic evolution of norwegian country rock eclogites as deduced from mineral inclusions and compositional zoning in garnets abstract detailed studies of pre early syn and post eclogite mineral associations in some west norwegian country rock eclogites have made it possible to reconstruct their metamorphic evolution pre eclogite stages are represented by various amphibolite facies associations found in the central parts of prograde zoned garnets early and syn eclogite stages are represented by various eclogitic assemblages containing low and high jd omphacites respectively the former located in the intermediate zones and the latter in the outermost rims of prograde zoned garnets and in the matrix post eclogite stages include granulite amphibolite and greenschist facies associations representing replacement phases after higher grade assemblages p t estimates indicate a prograde evolution along an extremely steep p t gradient 7 9 kbar over 100 200 c while the initial post eclogite evolution involved a nearly adiabatic decompression on the order of 10 kbar

geomorphologically effective floods from moraine dammed lakes in the cordillera blanca peru abstract outburst floods originating in moraine dammed lakes represent a significant geomorphological process as well as a specific type of threat for local communities in the cordillera blanca peru 8 5 10 s 77 78 w an exceptional concentration of catastrophic floods has been reported from the cordillera blanca in the first half of 20th century 1930s 1950s leading to thousands of fatalities the main objective of this paper is to provide a revised and comprehensive overview of geomorphologically effective floods in the area of interest using various documentary data sources verified by analysis of remotely sensed images 1948 2013 and enhanced by original field data verified events n 28 4 not mentioned before are analysed from the perspective of spatiotemporal distribution pre flood conditions causes mechanisms and geomorphological impacts as well as socioeconomical consequences revealing certain patterns and similar features glofs are further classified according to their magnitude 5 extreme events 8 major events and 15 minor events are distinguished referring to the quantified geomorphological and socioeconomical impacts selected moraine dams and flood deposits are dated using lichenometric dating special attention is given to moraine dam breaches the most frequent type of water release with the most significant consequences selected major events and their consequences are studied in detail in a separate section finally a general schematic model of lake formation growth and post flood evolution reflecting initial topographical setting and glacier retreat is introduced and the utilization of the obtained results is outlined

uranium lead zircon and titanite ages from the northern portion of the western gneiss region south central norway abstract the geochronologic history of the northern portion of the western gneiss region south central norway has been investigated by u pb analyses of zircon and titanite from various basement units and one supracrustal gneiss a six point four zircon and two titanite discordia line from a migmatite melt pod and its host gneiss astfjord migmatite gneiss defines upper and lower intercept ages of 1659 1 1 8 ma and 393 6 3 6 ma respectively the upper intercept age is interpreted as a time of tonalite emplacement and migmatite formation in the region a seven point three zircon and four titanite discordia line from the ingdal granite gneiss has similar upper and lower intercept ages 1652 9 1 7 ma and 396 1 4 9 ma respectively and the upper intercept age is interpreted as the time of granite crystallization the lower intercept age from both theastfjord migmatite gneiss and the ingdal granite gneiss is interpreted as the time of regional metamorphic resetting and is evidence for caledonian influence in the region titanite from these two gneiss units as well as from other tonalite granite and supracrustal gneisses throughout the western gneiss region displays a remarkably uniform pattern of discordance titanite discordance is variable from 6 to 100 and in general the degree of discordance is proportional to the caledonian metamorphic grade of nearby supracrustal schists episodic diffusional lead loss from titanite during caledonian metamorphism probably caused the discordance pattern but a combined mechanism of mixing and diffusional lead loss cannot be ruled out in any case the seventeen point titanite and zircon discordia line clearly indicates that 1 the bulk of the granitoid terrane in this portion of the western gneiss region was emplaced migmatized and cooled in a short time interval about 1657 ma ago 2 a second short lived thermal event that exceeded the blocking temperature of titanite occurred about 395 ma ago and 3 titanite and zircon in the region were not isotopically disturbed by comparable geologic events in the period from 1657 to 395 ma or at any time after 395 ma

eclogite formation and dynamics of crustal roots under continental collision zones field observations on deep parts of the root zone of the caledonian orogen are combined with the geophysical data available for recent continental collision zones such as the alps to provide a model for dynamics of crustal root zones rocks descending into the root zone are locally infiltrated by fluids which cause eclogitization along shear zones and fluid pathways the eclogite facies rocks vary in density from 3 1 to 3 6 g cm 3 reflecting the compositional variation in their protoliths where the amount of highly ductile eclogitic material reaches about 40 the descending crustal segment loses its coherence and disintegrates into a breccia where blocks of granulite facies rocks float in a matrix of eclogite material a density stratified root zone develops where light unreacted or partly eclogitized material floats on an ocean dominated by eclogite facies rocks the top of which may correspond to the moho catastrophic decent of this eclogitic layer may 1 transport blocks of light material to depths of 90 km which upon further disintegration due to eclogitization are released and return by buoyancy forces to the crust 2 result in extension and uplift of the partly eclogitized lighter material

uplift of tibet from eclogites to granulites implications for the andean plateau and the variscan belt abstract using a simplified petrogenetic grid and a one dimensional thermal model to compute the evolution of the density of the crust with time the contribution to the uplift of tibet of metamorphic transitions in the lower crust is shown to be large the computations are made for a lower crust of either mafic or intermediate composition a mafic lower crust would have a mantle like density incompatible with seismological results this conclusion implies that any pre thickening gabbroic lower crust has been removed during the orogenic process a lower crust of intermediate composition would be affected by about 3 km of post thickening uplift over a few tens of millions of years this uplift is essentially the result of the eclogite to granulite transformation the resulting altitude matches the present altitude and does not require any delamination of the mantle lithosphere such a process would also explain why the neogene uplift of tibet to an average elevation of 5 km appears to have occurred without crustal shortening the same model may explain the uplift of the altiplano puna plateau which also occurred without surface shortening since about 10 ma a comparison is made with the now collapsed variscan high mountain belt for which there is evidence of a progressive increase of the temperature in the crust over tens of million years

pseudotachylytes generated during seismic faulting and eclogitization of the deep crust pseudotachylytes are typically interpreted to have formed by frictional melting during coseismic faulting within the upper to middle crust pseudotachylytes in the bergen arcs of western norway contain microlites including omphacite garnet plagioclase and quartz this eclogite facies assemblage is stable at temperatures of about 800 c and pressures of 18 to 19 kilobars corresponding to depths of 60 kilometers or more the pseudotachylytes are exposed in grenvillian granulites that locally underwent fluid induced eclogitization and corresponding volume reduction of approximately 10 percent during the caledonian continental collision the pseudotachylytes may have formed as a result of the rapid relaxation of stresses caused by the eclogitization process