crustal reworking at nanga parbat pakistan metamorphic consequences of thermal mechanical coupling facilitated by erosion within the syntaxial bends of the india asia collision the himalaya terminate abruptly in a pair of metamorphic massifs nanga parbat in the west and namche barwa in the east are actively deforming antiformal domes which expose quaternary metamorphic rocks and granites the massifs are transected by major himalayan rivers indus and tsangpo and are loci of deep and rapid exhumation on the basis of velocity and attenuation tomography and microseismic magnetotelluric geochronological petrological structural and geomorphic data we have collected at nanga parbat we propose a model in which this intense metamorphic and structural reworking of crustal lithosphere is a consequence of strain focusing caused by significant erosion within deep gorges cut by the indus and tsangpo as these rivers turn sharply toward the foreland and exit their host syntaxes the localization of this phenomenon at the terminations of the himalayan arc owes its origin to both regional and local feedbacks between erosion and tectonics

slip rate measurements on the karakorum fault may imply secular variations in fault motion beryllium 10 surface exposure dating of offset moraines on one branch of the karakorum fault west of the gar basin yields a long term 140 to 20 thousand year right lateral slip rate of 10 7 0 7 millimeters per year this rate is 10 times larger than that inferred from recent insar analyses 1 3 millimeters per year that span 8 years and sample all branches of the fault the difference in slip rate determinations suggests that large rate fluctuations may exist over centennial or millennial time scales such fluctuations would be consistent with mechanical coupling between the seismogenic brittle creep and ductile shear sections of faults that reach deep into the crust

paraglacial rock slope stability glaciation and deglaciation along with their associated climatic and non climatic processes modify slope stresses and influence slope stability paraglacial slope failures are those that are a part of or influenced by the transition from glacial conditions to non glacial conditions gravitational failure of rock slopes is a primary and dominant process of slope evolution in mountainous terrain and is the subject of this paper which 1 reviews the approaches taken for researching paraglacial rock slope failure patterns and processes 2 summarises the spatial and temporal patterns of post glacial failures 3 assesses the factors influencing slope stability during glaciation and deglaciation 4 explores some of the applications of paraglacial research and 5 highlights some of the outstanding issues to be resolved and provides recommendations for terminology relating to paraglacial slope processes

nature and timing of large landslides in the himalaya and transhimalaya of northern india four large landslides each with a debris volume 10 6 m 3 in the himalaya and transhimalaya of northern india were examined mapped and dated using 10 be terrestrial cosmogenic radionuclide surface exposure dating the landslides date to 7 7 1 0 ka darcha 7 9 0 8 ka patseo 6 6 0 4 ka kelang serai and 8 5 0 5 ka chilam comparison of slip surface dips and physically reasonable angles of internal friction suggests that the landslides may have been triggered by increased pore water pressure seismic shaking or a combination of these two processes however the steepness of discontinuities in the darcha rock slope suggests that it was more likely to have started as a consequence of gravitationally induced buckling of planar slabs deglaciation of the region occurred more than 2000 years before the darcha patseo and kelang serai landslides it is unlikely that glacial debuttressing was responsible for triggering the landslides the four landslides their causes potential triggers and mechanisms and their ages are compared to 12 previously dated large landslides in the region fourteen of the 16 dated landslides occurred during periods of intensified monsoons seismic shaking however cannot be ruled out as a mechanism for landslide initiation because the himalaya has experienced great earthquakes on centennial to millennial timescales the average holocene landscape lowering due to large landslides for the lahul region which contains the darcha patseo and kelang serai landslides is w0 12 mm yr previously published large landslide landscape lowering rates for the himalaya differ significantly furthermore regional glacial and fluvial denudation rates for the himalaya are more than an order of magnitude greater this difference highlights the lack of large landslide data lack of chronology problems associated with single catchment large landslide based calculations and the need for regional landscape lowering determinations over a standardized time period

quaternary glaciation of the himalayan tibetan orogen glacial geological evidence from throughout the himalayan tibetan orogen is examined to determine the timing and extent of late quaternary glaciation in this region and its relation to similar changes on a global scale the evidence summarised here supports the existence of expanded ice caps and extensive valley glacier systems throughout the region during the late quaternary however it cannot yet be determined whether the timing of the extent of maximum glaciation was synchronous throughout the entire region or whether the response was more varied the lack of organic material needed for radiocarbon dating has hindered past progress in glacial reconstruction however application of optically stimulated luminescence and terrestrial cosmogenic radionuclide methods has recently expanded the number of chronologies throughout the region limits to the precision and accuracy available with these methods and more importantly geological uncertainty imposed by processes of moraine formation and alteration both conspire to limit the time resolution on which correlations can be made to milankovitch timescales several ka in order to put all studies on a common scale well dated sites have been re evaluated and all the published terrestrial cosmogenic nuclide ages for moraine boulders and glacially eroded surfaces in the himalayan tibetan orogen have been recalculated locally detailed studies indicate that there are considerable variations in the extent of glaciation from one region to the next during a glaciation glaciers throughout monsoon influenced tibet the himalaya and the transhimalaya are likely synchronous both with climate change resulting from oscillations in the south asian monsoon and with northern hemisphere cooling cycles in contrast glaciers in pamir in the far western regions of the himalayan tibet orogen advanced asynchronously relative to the other regions that are monsoon influenced regions and appear to be mainly in phase with the northern hemisphere cooling cycles broad patterns of local and regional variability based on equilibrium line altitudes have yet to be fully assessed but have the potential to help define changes in climatic gradients over time copyright 2008 john wiley sons ltd

cosmic ray labeling of erosion surfaces in situ nuclide production rates and erosion models a number of in situ cosmogenic radionuclides and stable nuclides have been measured in natural exposed rock surfaces with a view to study their in situ production and rock erosion rates 1 the in situ radionuclides can be used for a high resolution tomography of the erosional history of an exposed surface two stable nuclides 3he 21ne and five radionuclides 10be 26al 36cl 14c 39ar having half lives in the range of 300 1 5 106 yr half life are measurable in many rock types a prerequisite for the application of the in situ nuclides for the study of erosional histories of surfaces is a knowledge of their production rates under different irradiation conditions altitude latitude irradiation geometry and shielding relative nuclide production rates can be determined fairly accurately using the extensive available data on cosmic ray neutrons 2 absolute nuclide production rates cannot generally be predicted with any accuracy because of lack of data on excitation functions of nuclides unless some normalization is possible as was done in the case of several cosmic ray produced isotopes in the atmosphere 3 based on a recent natural calibration experiment in which erosion free surfaces exposed to cosmic radiation for 11 000 yrs were sampled the absolute production rates of 10be and 26al in quartz have been accurately estimated for mountain altitudes in sierra nevada 4 the absolute production rates of 10be and 26al in quartz can therefore be estimated fairly accurately for any given latitude and altitude some measurements of 14c in rocks of low erosion rate 5 similarly allow an estimate of its production rate attempts made to measure the in situ production rates of 3he in rocks have not yet led to a convergent production rate in view of the importance of knowing the production rates of isotopes of he ne and ar i present here theoretical estimates of their production rates based on available cross section data i discuss the information that can be extracted from the study of the in situ nuclides in rocks useful parameters characterizing the exposure history of a rock surface are 1 the effective surface exposure age and 2 the time averaged erosion rate the implications of these parameters for single and multiple nuclide studies are discussed in terms of the erosion models considered

rupture process of the 1980 izu hanto toho oki earthquake deduced from strong motion seismograms abstract the 1980 izu hanto toho oki earthquake is studied in detail using near field strong motion seismograms recorded at japan meteorological agency stations a seismogram inversion method is applied to deduce the dislocation distribution and the character of rupture propagation during this earthquake this earthquake involves left lateral strike slip motion on the almost vertical plane with a strike of n10 w the fault plane is shallower than about 12 km in depth and the length is about 20 km the large dislocation large seismic moment occurs near the hypocenter and at the southern end of the fault plane the rupture propagates southward from the central part of the fault plane and spreads to the shallow area of the northern part of the fault plane after a delay of about 5 sec relative to the initiation of this earthquake the total seismic moment is about 7 10 25 dyne cm the aftershocks of magnitude equal to or greater than 4 0 take place in the areas where high stresses are expected to remain after this earthquake the mechanical weakness of small submarine monogenetic volcanoes which are located above the source region seems to affect the rupture process of this earthquake

composition diagenesis and weathering of the sediments and basement of the callabonna sub basin central australia implications for landscape evolution abstract the evolution of the callabonna sub basin central australia is described in terms of sediment provenance stratigraphy sedimentology and postdepositional mineral and chemical alteration six mineral exploration drillholes in the mundi mundi plain were studied using a combination of qualitative and quantitative xrd pimatm portable infrared mineral analyzer xrf normative analysis and sem the sedimentary cover consists of 160 210 m of diagenetically modified fluvio lacustrine tertiary clay silt and sand comprising sandy mottled and gray clay units overlain by quaternary soil the basement consists of weathered proterozoic schist gneiss siltstone and shale quartz kaolinite smectite and muscovite are the dominant minerals within the sediments whereas the weathered bedrock contains quartz feldspar kaolinite illite and muscovite characteristic wavelength absorption features from pimatm show that the youngest sandy clay unit exhibits the lowest reflectance intensities because of its lower diagenetic maturity weathering of primary minerals within the basement produced an illite kaolinite rich saprolite whose clays exhibit strong reflectance intensities and well developed crystallinity the micromorphology of all secondary products reflects their environment of crystallization low porosity and anoxic conditions within the sediments resulted in poorly developed clays of variable textures colors and compositions conversely the weathered bedrock developed over protracted periods of in situ weathering resulting in better developed secondary products this study distinguishes between preburial weathering of the basement detrital mineralogy postdepositional alteration of the sedimentary cover and subsequent weathering of previously formed mineral assemblages this has widespread implications for paleotopographic weathering reconstitution and landscape evolution thus 1 the extent of weathering of basement relative to diagenesis and maturity of sediments and gradational nature of their unconformity suggests that most of the alteration of basement occurred prior to and was sustained after deposition of sediments and 2 morphotectonic evolution of the region controlled the composition of transported materials by changing the style and patterns of fluvial systems further influencing the distribution and preservation of sediments and weathered bedrock and hence regional landscape morphology

micromorphology of iceberg scour in clays glacial lake agassiz manitoba canada abstract icebergs plough through unconsolidated lake sea sediments gouging out kilometre long grooves 100s of metres wide and tens of metres deep although the surface morphology of iceberg scours is well documented little is known about what scours look like in stratigraphic section particularly where surface characteristics are absent e g through decay or burial this investigation establishes a definitive suite of diagnostic criteria for identifying iceberg scours in clays by macroscopically and microscopically 2d thin sections examining sediment deformation below iceberg scours in former glacial lake agassiz manitoba canada structures unequivocally attributed to iceberg scour in this investigation include sub horizontal microfabrics folds sheath folds augen shapes normal faults reverse thrust faults discrete shears partially destroyed clasts intraclasts type iii multiple domains water escape structures flow structures unistrial plasmic fabric dropstones realigned bedding and specific structural sequences this research will be particularly valuable in palaeoenvironmental reconstruction and in predicting glacial dynamics in addition it may eventually aid structural engineering on polar shelves which could be of great value to oil and gas companies

tectonic denudation and topographic development in the spanish sierra nevada 1 the denudation history of the rapidly uplifting western part of the spanish sierra nevada was assessed using apatite fission track aft ages and 10be analyses of bedrock and fluvial sediments major contrasts in the denudation history are recorded within the 27 km2 rio torrente catchment upland areas are characterized by low relief low slope angles and locally the preservation of shallow marine sediments which have experienced 2 km of denudation since circa 4 ma the minimum denudation rates of 0 4 mm yr 1 derived from aft also contrast with the slow medium term 104 years erosion rates 0 044 0 015 mm yr 1 estimated from 10be measurements at high elevations the local medium long term contrasts in denudation rates within the high sierra nevada indicate that much of the unroofing occurs by tectonic denudation on flat lying detachments in lower elevation parts of the catchment rapid river incision coupled to rock uplift has produced 1 6 km of relief implying that the rivers and adjacent hillslopes close to the edge of the orogen are sensitive to normal fault driven changes in base level however these changes are not transmitted into the low relief slowly eroding upland areas thus the core of the mountain range continues to increase in elevation until the limits of crustal strength are reached and denudation is initiated along planes of structural weakness we propose that this form of tectonic denudation provides an effective limit to relief in young orogens

the relative efficacy of fluvial and glacial erosion over modern to orogenic timescales it has been debated whether rivers or glaciers are more effective agents of erosion a global compilation of erosion rates reveals that both are capable of generating rates of erosion that match or exceed the highest rates of rock uplift since the late nineteenth century it has been debated whether rivers or glaciers are more effective agents of erosion1 the dramatic landscapes associated with glaciated terrain have often led to the argument that glaciers are more erosive than rivers and recent studies have documented the topographic signature of an ice controlled limit of mountain height known as the glacial buzz saw 2 3 here we present a new global compilation of erosion rates which questions the conventional view of glaciers and erosion in regions of rapid tectonic uplift erosion rates from rivers and glaciers both range from 1 to over 10 mm yr 1 indicating that both are capable of generating erosion rates matching or exceeding the highest rates of rock uplift moreover a comparison of erosion rates over timescales ranging from 101 to 107 years indicates that glacial erosion tends to decrease by one to two orders of magnitude over glacial cycles whereas fluvial erosion rates show no apparent dependence on time we conclude that tectonics controls rates of both fluvial and glacial erosion over millennial and longer timescales and that the highest rates of erosion 10 mm yr 1 generally result from a transient response to disturbance by volcanic eruptions climate change and modern agriculture

mass movements along a rapidly uplifting river valley an example from the upper jinsha river southeast margin of the tibetan plateau because of the rapid uplift of the tibetan plateau since the middle and late pleistocene the surrounding mountainous areas of the tibetan plateau also show a rapid uplift trend the study area is located in the upper reaches of the jinsha river southeastern tibetan plateau tectonically the study area is located in the eastern segment of the jinshajiang suture zone which is the weak belt of the lithosphere affected by the rapid uplift steep slopes are formed by the rapid vertical down cutting of rivers in the studied reach under the sustained action of the gravitational field the deformation and failure of slopes readily occur to better formulate development and risk mitigation plans a mass movement inventory map at the scale of 1 50 000 was prepared for the 100 km long reach a total of 247 mass movements of different types sizes and relative ages were mapped via image interpretation and detailed field survey the statistical analysis of their spatial distributions was performed using two relative concentration indexes the correlations between the spatial distribution and six common factors were analyzed elevation slope angle slope aspect lithology active fault and river system the geomorphological survey shows that the mass movements locally play an important role in the present day landscape evolution in addition the geomorphic features indicate that the mapped giant landslides can be classified as very old landslides and they very likely occurred under a different morphoclimatic environment than that of the present

tensile strength of dry remoulded soils as affected by properties of the clay fraction abstract changes in tensile strength with clay type clay particle size and amounts of spontaneously and mechanically dispersible clays were assessed for dry remoulded samples of eight australian vertisols and alfisols varying in clay mineralogy the effects of different clay content and particle size on tensile strength were also measured the average particle sizes of whole clay and of spontaneously and mechanically dispersible clays were also determined tensile strength of soils was influenced by the type and amount of clay present clay particle size and amount of dispersible clay soil strength increased with increasing clay content when the clay content increased beyond 20 there was a dramatic increase in soil strength indicating the possible role of particle arrangement correlations between different clay types clay particle sizes cation exchange capacity and tensile strength clearly illustrated that the sensitivity of tensile strength to these factors was greatest in soils dominated by smectite followed by illitic and then kaolinitic soils tensile strength of soils was positively and significantly correlated with both spontaneously and mechanically dispersible clays a significant negative correlation was obtained between clay particle size and tensile strength for illitic soils whereas the same linear relationship was not significant for smectitic soils however a significant negative exponential regression was obtained between the cube of clay particle size and tensile strength when the results of all soil samples were pooled together transmission electron micrographs tem showed a wider clay particle size distribution in smectites than in illites soils with the highest amounts of fine clay and the widest clay particle size distribution had higher tensile strengths the size of spontaneously dispersed clay particles was smaller than that of mechanically dispersed clay no difference in clay particle size was found between spontaneously and mechanically dispersible clays from mixtures of a fine clay with a basic sand and silt matrix regression collinearity diagnostics and principal component analyses were used to analyse the data a high correlation was found between the cation exchange capacity cec of clays and soil strength the principal component analysis indicated that spontaneously dispersible clay percentage of randomly interstratified minerals rim and cec were important factors in predicting the strength of remoulded soils

landslides and quaternary climate changes the state of the art abstract climatic factors are considered major causes and triggers of slope instability but the palaeoclimatic implications of landslides have not yet been systematically reviewed as inferred from landslides dated to the late glacial and holocene glacial interglacial transitions are the major intervals of enhanced landsliding but the length of this interval varies between distinct types of landscapes mass movements in non glaciated temperate mountain ranges arid and tropical regions and coastal areas intensified soon after the onset of the holocene alongside the warming and wetting of the climate whereas large rock slides in areas within the limits of pleistocene glaciations mostly show a millennial scale time lag with respect to glacier withdrawal although the incidence of landslides was ubiquitous throughout the holocene the mid to late holocene transition 5 4 ka was especially favourable for the origin of landslides across distinct types of landscapes indicating a strengthened role of mass movements during the culmination phases of interglacial climate optima in addition growing evidence suggests that the enhanced activity of landslides occurred during warmer interstadial conditions which is best demonstrated in the temporal coincidence of arid zone landslides with quaternary pluvials future progress in the understanding of the relationships between landslides and quaternary climate changes should benefit from the i extension of datasets of dated landslides ii geographical expansion of dating studies to regions with a lack of chronologically determined landslides e g tropics iii improvement of landslide dating strategies involving the incorporation of independent palaeoclimatic proxies and iv wider incorporation of numerical modeling within landslide dating studies

three dimensional fine velocity structure and hypocentral distribution of earthquakes beneath the kanto tokai district japan we determine the three dimensional p wave velocity structure beneath the kanto tokai district central japan and simultaneously relocated by inverting travel time data for 91 events that were observed at 61 stations operated by the national research center for disaster prevention the variance of the travel time data is reduced by 75 as compared to the variance for the routinely used laterally homogeneous model in general our velocity model is consistent with tectonic models of the kanto tokai district our velocity model is also in good agreement with seismic explosion data and bouguer gravity anomalies the uppermost layer from 0 to 16 km depth is characterized by lateral velocity differences of more than 20 we find low velocity zones beneath tokyo bay the middle of the boso peninsula and omae zaki where there are thick sedimentary layers a marked 30 km thick high velocity zone extends to the northeast and the west of the izu peninsula this zone dips gradually from the surface to a depth of 70 km in the eastern region and to a depth of 40 km in the western region and is interpreted as the philippine sea phs plate which is being subducted at the sagami and the suruga troughs the data unquestionably require a high velocity zone beneath mount tsukuba that cannot be explained in terms of present tectonic models we use our three dimensional velocity model to relocate about 23 000 earthquakes that took place from 1983 through 1985 the accuracy of the hypocentral parameters improved considerably as a result the double seismic zone within the subducting pacific plate is more clearly delineated than in previous studies the inclined seismic zone for the subducting phs plate coincides fairly well with the high velocity zone of our three dimensional velocity model

experimental study of soil microfabrics induced by isotropic stresses of wetting and drying this experimental study examines the relationship between texture and microfabric under isotropic stresses generated by wetting and drying this can be achieved by observing and measuring the reorganization of microfabrics plasmic fabrics and related distribution pattern rdp microfabrics are produced in the laboratory by mixing montmorillonite with various proportions of sand and silt and subjecting them to wetting and drying without confinement thin sections are cut to study their microfabrics results show broad and systematic variations in fabric with changes in texture fine matrix silt plus clay in physical continuity is developed in samples with low sand silt ratio and regardless of this ratio at high clay levels coarse porphyric and fine porphyric rdp are formed at low and high clay contents respectively plasmic fabrics are represented mainly by insepic and weakly developed mosepic and masepic fabrics in the matrix in the form of small plasma separations with random orientation and weak skelsepic plasma as embedded grain argillans on the other hand coarse matrix sand grains in physical continuity dominates the sandy samples which are associated with relatively thick and strongly birefringent free grain argillans giving well developed skelsepic fabric the rdp follows two major paths beginning with orthogranic very low clay content along the iunctic sequence at low clay silt ratio and along the chlamydic sequence at high ratio the regularities in fabric development are interpreted in the light of the dynamic properties and behaviour of the active clay fraction in a clay water system the pedogenetic implications of the results are explored and the term erdic fabric defined

dynamic adjustment of repeatedly observed levelling networks used in crustal vertical deformation monitoring abstract in order to monitor crustal vertical deformation in certain local areas by means of the geodetic method the levelling nets in these areas are usually observed at regular intervals in order to make a reasonable treatment of the results we have made some adjustments they are 1 a adjustment method of free level nets for a certain period of time 2 b successive condition adjustment of elevation differences and their rate of change 3 c dynamic condition adjustment with rate parameters of bench mark elevations as unknowns 4 d dynamic adjustment of repeatedly observed levelling nets for m periods 5 e dynamic adjustment with nonlinear movement model we have applied these methods to test calculations of levelling nets in several regions in addition we have performed statistical tests on the adjusted results of a certain levelling net and tried to infer the region of anomalous deformation in the area covered by this net

from gullies to mountain belts a review of sediment budgets at various scales this paper reviews the state of the art in the concept as well as in the application of sediment budgets in sedimentary research sediments are a product of mass dispersal at the earth surface and take part in global cycles sediment budgets aim at quantifying this mass transfer based on the principle of mass conservation and are the key to determine ancient fluxes of solid matter at the earth surface this involves fundamental questions about the interplay of uplift climate and denudation in mountain belts and transfer of sediments from the continents to the oceans as well as applied issues such as soil and gully erosion reservoir siltation and coastal protection first after introducing basic concepts relevant scales and methodologies the different components of quaternary routing systems from erosion in headwaters river systems glacial and paraglacial systems lakes deltas estuaries coasts shelves epicontinental seas and deep sea fans are discussed in terms of their sediment budget most suitable are sedimentologically closed or semi closed depositional environments e g alluvial fans lakes deltas and deep sea fans in a second step the dynamics of passive active and collisional tectonic settings and sediment budgets in related sedimentary basins are explored and new concepts of sediment portioning at large geodynamic scales are introduced ancient routing systems are more or less incomplete and may be intensively fragmented or destroyed in active tectonic settings in terms of sedimentary basin types rifts intracontinental and epicontinental settings are preferred objects of sediment budgets because of their persistence and relatively simple overall sedimentary architecture however closing basins such as foreland forearc retroarc piggy back and wedge top basins may provide excellent snapshots of orogenic sediment fluxes in a third step the large long lived routing systems of the amazon the ganges brahmaputra and the rhine are reviewed for each system estimates of either sediment volumes mass or sediment fluxes of continental and marine subsystems have been compiled in order to receive a complete routing in terms of mass conservation for specific time periods since the late glacial maximum as well as the cenozoic following lessons can be taken from these case studies i depositional centers and fluxes show strong shifts in space and time and call for caution when simply looking at subsystems ii the response times of these large systems are within the milankovich time interval thus lower than predicted from diffusion models iii cyclic routing of sediments in continental basins is much more dominated by climate human control than by eustacy and iv at long time scales ultimate sinks win over intermittent storage it is concluded from this review that the quantitative understanding of global sediment cycling over historic and geologic time and its response to allogenic forcing is still in its infancy and further research is needed towards a holistic view of sediment routing systems at various temporal and spatial scales and their coupling with global biogeochemical cycles this includes i to better determine response times of large routing systems by linking quaternary with cenozoic sediment budgets and continental with marine sub systems ii to combine advanced provenance techniques with sediment budgets in order to reconstruct ancient systems iii to study sediment partitioning at the basin scale iv to reconcile continental supply dominated sequence stratigraphy with the eustatic dominated marine concept and iv to account for non actualism of ancient systems with respect to their erosion and transport mode in particular during glaciations and pronounced arid intervals glacial and eolian sediment routing may cross over hydrologic boundaries of drainage basins thus challenging the principle of mass conservation

catastrophic landslide deposits in the karakoram himalaya in july 1986 three catastrophic landslides deposited about 20 x 106 cubic meters of debris on bualtar glacier in the karakoram himalaya a sudden acceleration and superficial breakup of the glacier provided an opportunity to examine the fresh deposits in depth beneath a surface layer of large boulders finer materials mainly sand and silt made up half of the total volume the fine materials were formed during the rock avalanche from mostly intact massive rock of the source zone velocity estimates suggest that this disaggregation occurred in less than 2 minutes coarse materials remained in bands of uniform lithology but the fine materials had diffused throughout the landslides a small amount of carbonate appears to have been calcined by frictional heating presumably at the base of the initial sliding masses these observations are relevant to understanding the mechanisms of catastrophic landslides other nearby rock avalanche deposits indicate that landslides are an important geomorphic process in the area and that they pose a continuing risk to human activity

landforms and landscape evolution in the skardu shigar and braldu valleys central karakoram abstract the central karakoram which includes k2 in pakistan is one of the most rapidly rising areas on earth and exhibits complex topography and extreme relief impressive valley fills and glacial landforms are present throughout the valleys the dynamics of landscape evolution of the region are currently not well understood consequently the landforms were mapped and assessed in the skardu shigar and braldu valleys to elucidate the spatio temporal scale dependencies of surface processes active in the region these valleys were examined using geomorphic field methods remote sensing geomorphometry and terrestrial cosmogenic nuclides tcns surface exposure dating the glaciers in this region have oscillated considerably throughout the late quaternary and four glacial stages have been recognized including at least six glacial advances surface processes readjusted after glacier retreat and ubiquitous mass movements and catastrophic landsliding transported material from steep slopes to valley bottoms while glaciofluvial meltwater and glacier outburst floods redistributed sediment down valley glacier geochronology and late holocene ages of the outburst flood deposits indicate that landscape evolution has been dominated by glaciation and paraglaciation during the late quaternary

has focused denudation sustained active thrusting at the himalayan topographic front the geomorphic character of major river drainages in the himalayan foothills of central nepal suggests the existence of a discrete west northwest trending break in rock uplift rates that does not correspond to previously mapped faults the 40 ar 39 ar thermochronologic data from detrital muscovites with provenance from both sides of the discontinuity indicate that this geomorphic break also corresponds to a major discontinuity in cooling ages samples to the south are proterozoic to paleozoic whereas those to the north are miocene and younger combined these observations virtually require recent pliocene holocene motion on a thrust sense shear zone in the central nepal himalaya 20 30 km south of the main central thrust field observations are consistent with motion on a broad shear zone subparallel to the fabric of the lesser himalayan lithotectonic sequence the results suggest that motion on thrusts in the toe of the himalayan wedge may be synchronous with deeper exhumation on more hinterland structures in central nepal we speculate that this continued exhumation in the hinterland may be related to intense sustained erosion driven by focused orographic precipitation at the foot of the high himalaya

the hofðaholar rock avalanche sturzstrom chronological constraint of paraglacial landsliding on an icelandic hillslope the hof aholar rock avalanche in the skagafjor ur area of northern iceland was investigated on the basis of a geomorphological analysis of its landforms and close surrounding environment thanks

enhanced rock slope failure following ice sheet deglaciation timing and causes this research was supported by nerc cosmogenic isotope analysis facility grant number 9046 0308

the plate coupling in the tokai district the central japan inferred from the different data using triangular dislocation elements abstract we estimate interseismic coupling on the subducting plate interface in the tokai area central japan by inverting two geodetic data sets the data record surface motion between march 1996 to may 2000 one represents vertical motion deduced from the leveling observations and the other is the horizontal velocity field deduced from gps observations in the inversion we employed the analytical solutions of surface displacement due to a triangular dislocation element embedded in a homogeneous elastic half space in order to represent the curved plate interface the vertical data show that the most strongly coupled portion of the subduction interface is concentrated beneath omaezaki cape while the horizontal data show strongest coupling in the shallower region of the subducting plate interface the estimated maximum value of coupling from the horizontal data is 40 mm year while that from vertical data is 25 mm year

stress shear deformation and micromorphological clay orientation a synthesis of various concepts summary microscopic oriented clay bodies known as plasma separations to soil micromorphologists show various degrees of symmetry and regularity in their patterns they could be regarded as sensitive and reliable indicators of stress strain regime of a soil empirical and experimental evidence signifies the importance of stress specifically that generated by in situ swelling in the genesis of plasmic fabrics hitherto most work in this field is confined to geometric characterization with limited attempts to dynamic interpretations of their origin this paper enlists appropriate concepts in soil mechanics structural geology and agricultural engineering to interpret the possible stress strain components that rearrange fabric units into plasma separations some pertinent concepts including physico chemical behaviour of the clay water system shrink swell phenomenon stress strain deformation and failure of soil are employed to explain the origin of plasmic fabrics by mechanical principles a conceptual model is suggested to synthesize the conditions changes and consequences related to the formation of plasmic fabrics strongly developed plasma separations in natural soils are attributed to the establishment of an anisotropic state of stress generated by in situ swelling in conjunction with the passive pressure of lateral confinement and vertical overburden the difference between the maximum and minimum principal stresses produces a deviatoric stress that can at certain stages of a shrink swell cycle exceed the shear strength of the soil the extra stress is relieved plastically by shear deformation which is manifested as the alignment of platy particles in domain configuration by rotation and translation along the shear planes soil mainly fails in compressive plastic mode along a large number of small shear planes which form the plasma separations the formation of different types of sepic plasmic fabrics is discussed in relation to the stress strain regimes of soils

lateglacial rock slope failures in north west ireland age causes and implications nine postglacial quartzite rock slope failures rsfs in north west ireland were dated using cosmogenic 10be weighted mean rsf ages range from 17 7 0 9 to 12 5 0 7 ka or 16 6 0 7 to 11 7 0 5 ka depending on assumed 10be production rate all dated rsfs occurred within 5000 years following ice sheet deglaciation at 17 4ka 16 3 ka and all but two occurred within 2000 years after deglaciation the timing of rsfs rules out glacial debuttressing permafrost degradation and enhanced deglacial cleft water pressures as triggers of failure in most cases we infer that paraglacial stress release and associated fracture propagation were critical in reducing rock masses to critical stability although earthquakes caused by lateglacial glacio isostatic rebound and or release of stored tectonic stresses may have triggered failure in some or all cases in conjunction with data from related studies our results imply that most undated rsfs outside the limit of younger dryas glaciation in the british isles are of lateglacial age and that numerous lateglacial rsfs occurred inside these limits with subsequent removal of debris by glaciers they support the view that paraglacial rsf activity in tectonically stable intraplate terrains was concentrated within a few millennia following deglaciation

southward extrusion of tibetan crust and its effect on himalayan tectonics the tibetan plateau is a storehouse of excess gravitational potential energy accumulated through crustal thickening during india asia collision and the contrast in potential energy between the plateau and its surroundings strongly influences the modern tectonics of south asia the distribution of potential energy anomalies across the region derived from geopotential models indicates that the himalayan front is the optimal location for focused dissipation of excess energy stored in the plateau the modern pattern of deformation and erosion in the himalaya provides an efficient mechanism for such dissipation and a review of the neogene geological evolution of southern tibet and the himalaya shows that this mechanism has been operational for at least the past 20 million years this persistence of deformational and erosional style suggests to us that orogens like other complex systems can evolve toward steady state configurations maintained by the continuous flow of energy the capacity of erogenic systems to self organize into temporally persistent structural and erosional patterns suggests that the tectonic history of a mountain range may depend on local energetics as much as it does on far field plate interactions

secular and earthquake related vertical crustal movements in japan as deduced from tidal records 1951 1981 abstract monthly tidal records for the last 31 years from about 100 tidal stations are used to delineate vertical crustal movements in japan a new computer aided processing system was created for this purpose its principle is differential use of tidal records in a region so that the oceanographic disturbances of common causes may be eliminated from the sea level data this method enables us to observe nearly absolute vertical land movement at tidal stations with a precision of a few centimeters the japanese islands are divided into nine regions taking oceanographic conditions into account general discussion on recent vertical movements has yielded several notable features and trends as follows 1 1 rapid and stationary subsidence in the northeastern part of japan presumably of tectonic origin 2 2 a complex pattern of uplift and subsidence in the southwestern part of japan which seems to reflect subduction of the philippine sea plate against the honshu block 3 3 relatively stable land on the japan sea side of honshu movements related to the earthquakes during the period 1951 1981 are also discussed although few of the cases show clear cut premonitory movements if abnormal movements in a coastal area appeared with an amplitude exceeding 2 or 3 cm we could detect them by the present system

bedrock incision rock uplift and threshold hillslopes in the northwestern himalayas the topography of tectonically active mountain ranges reflects a poorly understood competition between bedrock uplift and erosion dating of abandoned river cut surfaces in the northwestern himalayas reveals that the indus river incises through the bedrock at extremely high rates 2 12 mm yr 1 in the surrounding mountains the average angles of hillslopes are steep and essentially independent of erosion rate suggesting control by a common threshold process in this rapidly deforming region an equilibrium is maintained between bedrock uplift and river incision with landsliding allowing hillslopes to adjust efficiently to rapid river down cutting

the role of mass movements on landscape evolution in the central karakoram discussion and speculation abstract mass movement constitutes an important process in the evolution of landscapes in mountain regions however the role of massive slope failures in denudational unloading and landscape evolution has not been extensively studied large scale mass movements in one of the greatest mountain ranges on earth the central karakoram in pakistan were therefore examined to help evaluate their role in landscape evolution in high mountains specifically four major mass movement complexes ghoro choh rock avalanche busper sackung and slope failure gomboro slope failure and urdokas rockslide each comprising 10 6 m 3 of debris were assessed and mapped in detail two of these mass movement complexes the ghoro choh rock avalanche and gomboro slope failure were dated using terrestrial cosmogenic nuclides the ages of occurrence of the mass movement complexes studied in the central karakoram date from the late pleistocene to the holocene the four major mass movement complexes all involved the removal of mass from the tops of mountain ridges and peaks that failed and were subsequently transported towards the bottom of their respective valleys such massive movement of mass is anomalous compared to other forms of mass movement and is generally spatially coincident with exposed deeply buried gneiss dome structures these large scale movements appear to be part of a coupled system involving river incision and glacial debuttrussing although earthquakes might have triggered these mass movements this study illustrates the role of climate forcing which is part of a coupled system of denudational unloading but it is unclear whether high magnitude low frequency events such as these initiate the isostatic and tectonic influx of mass or if sustained high magnitude denudation resulting from a coupled system is responsible for the exhumation of buried structures

evidence against quaternary slip on the northern karakorum fault suggests kinematic reorganization at the western end of the himalayan tibetan orogen abstract while the right slip karakorum fault is one of the most prominent structures in the himalayan tibetan orogen its evolution and role in accommodating deformation related to the collision between india and asia is controversial different models interpret the karakorum fault as either 1 a long lived stable feature analogous to a plate boundary structure or 2 an evolving fault system with limited displacement 150 ka overly the trace of the two strands of the karakorum fault and show no evidence of tectonic disturbance 2 older late pliocene to early quaternary loess deposits which overlie the trace of the fault are either undisturbed or are cut by small normal fault scarps with no evidence of strike slip displacement 3 east west trending bedrock incised stream valleys up to 500 m deep cross both strands of the fault with no sign of lateral deflection i suggest that termination of slip along the northern segment of the karakorum fault occurred in the pliocene due to southward propagation of the altyn tagh fault system along the longmu co gozha co fault and impingement of the karakorum fault this study suggests that large intracontinental strike slip faults embedded within orogenic plateaus are transient features which should be expected to have complicated kinematic histories and short life spans relative to the life of an orogenic belt

nature and timing of quaternary glaciation in the himalayan tibetan orogen abstract much effort has been made in recent years to define the timing and extent of quaternary glaciation throughout the himalayan tibetan orogen these studies are challenging because of the logistical and political inaccessibility of the region and the inherent problems associated with the application of numerical dating techniques nevertheless the studies are providing abundant evidence for significant glacial advances throughout the last several glacial cycles and are beginning to accurately define the extent and timing of glaciation in selected regions studies are showing that himalayan tibetan glaciers in arid regions during the last glacial cycle reached their maximum extent early in the cycle and that global last glacial maximum glacier advances were significantly less extensive however along the more monsoonal influenced greater himalaya there is increasing evidence to suggest that glaciation was more extensive later in the last glacial cycle but this has yet to be fully assessed in addition the new studies are showing that throughout most himalayan tibetan regions significant glacier advances occurred during the lateglacial and early holocene with minor advances in some regions during the mid holocene the still relatively poor chronological control in the himalayan tibetan orogen however makes it difficult to construct correlations across the region and with regions elsewhere in the world this in turn makes it hard to assess the relative importance of the different climatic mechanisms that force glaciation across the himalayan tibetan orogen and to quantify paleoclimate change in this high altitude subtropical region the lateglacial and holocene glacial records however are particularly well preserved in several himalayan tibetan regions glacial successions such as these have the greatest potential to be examined in detail using newly developing numerical dating and geomorphic and sedimentologic methods to derive high resolution terrestrial records of glaciation that will help in paleoclimatic reconstruction for high altitude subtropical regions

eocene paleosols on king george island maritime antarctica macromorphology micromorphology and mineralogy abstract we investigated the origin of reddish layers between basalt flows in an early eocene volcanic succession in king george island maritime antarctica previous studies in the area classified these layers as regolith surfaces baked zones and paleosols but the properties of these layers and the reasons for their classification are not clarified since the early eocene epoch was one of the warmest phases on earth during the cenozoic a proper investigation of these layers is crucial to obtain additional regional information about the paleoenvironment the focus of this study is on three profiles located in the admiralty bay on king george island they were classified as paleosols based on field micromorphological and mineralogical properties main soil forming processes identified by micromorphological analyses were clay neoformation pedo bioturbation and a weak redoximorphosis the occurrence of plant residues in all profiles was a reliable indicator that these soils formed a land surface during the early eocene abundant weathered volcanic glass and pyroclasts may indicate andosolization although the main diagnostic features for andosols which are the presence of nanocrystalline minerals and organic matter accumulation were not detected or only in small amounts respectively the long term burial of the paleosol could be a reason for lacking of these diagnostic features clay minerals associated with moderately weathered volcanic soils smectite were detected in the x ray diffraction analysis a predominantly reddish colour of most of the soil horizons is given by hematite confirmed by the determination of pedogenic oxides nevertheless rubification was not solely a result of pedogenesis but also of reddening of oxyhydroxides by dehydration during diagenesis other diagenetic processes were burial compaction loss of organic matter and induration in the horizons directly buried by a basalt flow voids were filled by zeolite crystals an effect related to lava cooling another possible diagenetic effect was the geochemical rejuvenation and homogenization of the profiles despite the occurrence of these features the results are in agreement with previous studies indicating a humid temperate paleoclimate for king george island during the early eocene

rates of fluvial bedrock incision within an actively uplifting orogen central karakoram mountains northern pakistan abstract terrestrial cosmogenic nuclide tcn 10 be surface exposure ages for strath terraces along the braldu river in the central karakoram mountains range from 0 8 to 11 ka this indicates that strath terrace formation began to occur rapidly upon deglaciation of the braldu valley at 11 ka fluvial incision rates for the braldu river based on the tcn ages for strath terraces range from 2 to 29 mm a the fluvial incision rates for the central gorged section of the braldu river are an order of magnitude greater than those for the upper and lower reaches this difference is reflected in the modern stream gradient and valley morphology the higher incision rates in the gorged central reach of the braldu river likely reflect differential uplift above the main karakoram thrust that has resulted in the presence of a knickpoint and more rapid fluvial incision the postglacial fluvial incision rate 2 3 mm a for the upper and lower reaches are of the same order of magnitude as the exhumation rates estimated from previously published thermochronological data for the baltoro granite in the upper catchment region and for the adjacent himalayan regions

rock slope failure following late pleistocene deglaciation on tectonically stable mountainous terrain the ages of 31 postglacial rock slope failures rsfs in scotland and nw ireland derived from 89 cosmogenic isotope exposure ages are employed to analyse the temporal pattern of failure and its relationship to the timing of deglaciation rates of glacio isostatic crustal uplift and periods of rapid climate change rsf ages span almost the whole period since ice sheet retreat from 18 2 1 2 ka to 1 7 0 2 ka or from 17 1 1 0 ka to 1 5 0 1 ka depending on the production rate used in 10 be age calculation but catastrophic failure of rock slopes was w4 6 times more frequent prior to w11 7 ka than during the holocene 95 of dated rsfs at sites deglaciated during retreat of the last ice sheet occurred within w5400 years after deglaciation with peak rsf activity 1600e1700 years after deglaciation this time lag is inferred to represent 1 stress release initiated by deglacial unloading leading to 2 time dependent rock mass strength degradation through progressive failure plane development and ultimately 3 to either spontaneous kinematic release or failure triggered by some extrinsic mechanism by contrast 11 dated rsfs at sites reoccupied by glacier ice during the younger dryas stade yds of w12 9e11 7 ka exhibit no clear temporal pattern suggesting that glacial reoccupance during the yds was ineffective in preconditioning a renewed cycle of enhanced rsf activity comparison of timing of individual rsfs with that of deglaciation and rapid warming events at w14 7 ka and w11 7 ka suggests that glacial debuttressing enhanced joint waterpressuresduringdeglaciationandthawofpermafrosticeinrockjointscouldhavetriggeredfailurein only a small number of cases conversely the timing of maximum rsf activity following ice sheet deglaciation corresponds broadly with maximum rates of glacio isostatic crustal uplift suggesting that the two are linked by enhanced seismic activity a seismic failure trigger is consistent with full slope failure at all sites where failure planes are clearly defined our results indicate that numerous rsfs must have occurred in areas that were reoccupied by glacier ice during the yds but have not been identified because runout debris was removed by yds glaciers more generally they provide the first reliably dated body of evidence to support the view that retreat of the last ice sheets in tectonically stable mountainous terrain initiated a period of enhanced rock slope failure due to deglacial unloading and probably lateglacial seismic activity implying that most undated rsfs in such areas are probably of lateglacial or veryearly holocene age they also demonstrate however that a low frequency of rsf activity extended throughout the holocene

quaternary moraines vs catastrophic rock avalanches in the karakoram himalaya northern pakistan a history and conception of glacial events for the central karakoram himalaya proposed some 80 years ago by giotto dainelli are largely accepted today however certain deposits identified as terminal moraine complexes marking glacial episodes were actually emplaced by rock avalanches in the skardu and shigar intermontane basins of baltistan at least 15 rock avalanche events were previously mapped as moraine or till criteria used for distinguishing these catastrophic landslide deposits emphasize homogeneous lithology of rubble and matrix clast shape facies characteristics the large scale unity of emplacement and morphological relations to valley topography the deposits of three events at katzarah satpura and the north end of shigar valley have been reconstructed in detail thick supraglacial debris does not result in similar deposits extensive valley fills river terraces large sediment fans and lacustrine sediments formerly attributed to late glacial conditions are reinterpreted as postglacial events involving rock avalanches that interrupted fluvial development existing reconstructions of glaciations are left in doubt especially late glacial events in the central karakoram as are the roles assigned to karakoram main indus valley and western himalayan ice

cosmogenic age constraints on post lgm catastrophic rock slope failures in the tatra mountains western carpathians textcopyright 2015 elsevier b v although deglaciation is one of the crucial factors controlling the stability of slopes in high mountains the chronological response of rock slope failure rsf to glacier retreat still remains poorly known here we provide the first cosmogenic 10be age constraints on prominent rock avalanches and rockfalls collectively termed rock slope failures rsfs from the tatra mountains the highest mountain range with the most pronounced glacier morphology within the carpathians six representative rsfs were selected for surface exposure dating in the mountain range two sites are situated in the western part with less pronounced local relief and gentler slope gradient and four come from the highest eastern part with oversteepened rock slopes our dataset also contains the largest known rsf in the tatra mountains the koprova rock avalanche with a volume of 5 4 106m3 based on 26 10be dated boulders the weighted mean ages of individual rsf accumulations range between 20 2 1 2 and 10 1 0 3ka our results suggest that smaller structurally predisposed failures mainly rockfalls in the steepest parts of the mountains reacted immediately i e a few hundred years to deglaciation whereas more complex slope deformations in terrain with lower local relief involving the largest rock avalanche in the tatra mountains experienced a substantial time lag i e several millennia in respect to ice retreat in the case of delayed rsfs their origin can be well correlated with warmer and more humid periods in the lateglacial early holocene such as the bolling allerod chronozone and after the onset of the holocene

coupling of rock uplift and river incision in the namche barwa gyala peri massif tibet geodynamic modeling demonstrates the strong potential for erosion to influence the pattern and style of deformation in active mountain belts but field studies yield conflicting views on the importance of erosion in influencing orogenesis here we compare patterns in river power inferred excess fluvial transport capacity topographic relief precipitation and mineral cooling ages to assess the coupling between surface erosion and rock uplift within the vicinity of the namche barwa gyala peri massif an active antiformal structure within the eastern himalayan syntaxis our rich and dense data set reveals a tight spatial correspondence of fluvial incision potential high relief and young cooling ages the spatial coincidence is most easily explained by a sustained balance between rock uplift and denudation driven by river incision over at least the last 1 m y the yarlung tsangpo brahmaputra river is the largest and most powerful river in the himalaya and two lines of evidence point to its active role in the dynamic interaction of local erosion rock uplift thermal weakening of the lithosphere and deformation 1 whereas along the rest of the himalayan front high relief and high rock uplift rates are essentially continuous the high relief and rapid exhumation in the syntaxis is restricted to a bull s eye pattern exactly where the largest river in the himalaya the yarlung tsangpo brahmaputra has the most energy per unit area available to erode its channel and transport sediment 2 the location of rapid incision on the yarlung tsangpo brahmaputra has been pinned for at least 1 m y and without compensatory uplift of the namche barwa gyala peri massif during this time the river would have eroded headward rapidly incising deeply into tibet

age evaluation and causation of rock slope failures along the western margin of the antrim lava group alg northern ireland based on cosmogenic isotope 36cl surface exposure dating the temporal pattern of postglacial rock slope failure in a glaciated upland area of ireland the western margin of the antrim lava group was evaluated using both 36cl exposure dating of surface boulders on run out debris and 14c dating of basal organic soils from depressions on the debris the majority of the 36cl ages 21 15 ka indicate that major failures occurred during or immediately following local deglaciation 18 17 ka other ages 14 9 ka suggest some later smaller scale failures during the lateglacial and or early holocene the 14c ages 2 36 0 15 cal ka bp indicate the very late onset of organic accumulation and do not provide close limiting age constraints rock slope failure during or immediately following local deglaciation was probably in response to some combination of glacial debuttressing slope steepening and paraglacial stress release later failures may have been triggered by seismic activity associated with glacio isostatic crustal uplift and or permafrost degradation consequent upon climate change the 36cl ages support the findings of previous studies that show the deglacial lateglacial period in northwest ireland and scotland to have been one of enhanced rock slope failure

clay mineralogy as a crucial factor in badland hillslope processes abstract comprehensive and important work has been done in understanding badland processes on both the big scale and more recently on smaller scale in order to understand the subtle differences between sites however most studies lack important information regarding clay mineralogy and their importance for weathering processes type and rate of weathering depend on material physico chemical properties climatic regimes and slope characteristics as weathering progresses the surface conditions change influencing erosion processes usually badland lithologies are reported as sodium rich highly dispersive materials but that is not invariably true the primary objective of this study is to show that clay minerals have an important role in defining surface and subsurface processes on badland hillslopes field studies conducted in dinosaur park badlands alberta canada chinguacousy badlands ontario canada and sestino badlands tuscany italy have shown that there are two dominant clay rich lithologies smectite rich and smectite poor mudrocks different surface crust and weathering profiles were observed on smectite rich mudrocks during two field years with distinct precipitation inputs after a dry fall winter season the popcorn surface was very well developed 2 3 cm the subsurface layer 10 15 cm thick overlaid the layer of smaller shards followed by the unweathered material after a very wet fall winter season the surface layer was denser and thinner 0 5 cm with wider cracks and a thin subsurface layer attached to the crust weathering profiles on smectite poor lithologies did not show any differences with variable climatic conditions a thin surface layer was composed of soft thin and small 0 5 0 3 0 1 cm shards a layer of larger shards overlying unweathered material was beneath it in order to better understand the described occurrences badland materials were monitored in controlled laboratory conditions during an incremental weathering experiment six samples of each material were subjected to 10 cycles of simulated rainfall which duration ranged 10 60 min very short rainfalls 10 20 min can cause swelling of clay minerals in smectite rich materials and formation of popcorn surface during drying periods during subsequent wetting drying periods the crust becomes flatter and denser and desiccation cracks become wider and deeper samples subjected to 50 and 60 min of rainfall showed maximum swelling after only one cycle of rainfall after this swift swelling samples became unstable and dispersive during subsequent wetting dispersion became dominant resulting in flatter surfaces thinner crust and narrower desiccation cracks smectite poor mudrocks appeared to be resistant to variable wetting and drying large shards broke down into smaller due to differential swelling of illite and chlorite once they were reduced to tiny flaky shards the surface became compacted the surface cracks served as the initial pathways for sediment and water movement knowing if the material is smectite rich or smectite poor can help in prediction of processes and the erosion rates the amount intensity and duration of precipitation will determine not only the rate of weathering but also the type of the weathered surface on smectite rich surfaces smectite poor materials appear to be more resistant to change in precipitation

micromorphology of diamicton affected by iceberg keel scouring scoresby sund east greenland this research was primarily funded by the university of brighton s rising stars initiative and the school of environment and technology research investment fund with supplementary funds awarded by the quaternary research association the funding sources had no involvement in study design in collection analysis and interpretation of data in the writing of the article and in the decision to submit the article for publication

are sackungen diagnostic features of de glaciated mountains abstract deep seated gravitational slope deformations dsgsds with characteristic sackung landforms e g double crests trenches uphill facing scarps and toe bulging are considered by some researchers to be diagnostic features indicating past mountain glaciations however an extensive literature review on sackung features throughout the world reveals that in some regions paraglacial processes are not the causes of such phenomena sackungen occur across a diverse spectrum of mountain types with different morphoclimatic histories including regions that have never experienced glaciation to reinforce that sackungen may originate independently of glaciation we also include two case studies from the western carpathians czech republic and slovakia which are supported by detailed geomorphic mapping trenching and absolute dating 10 be 14 c and osl on the ond ejnik ridge outer western carpathians czech republic sackungen occur in the mid holocene in the medium high mountains which are beyond the pleistocene glacial limits on the salatin mt tatra mts slovakia the sackungen which occur in formerly glaciated terrain date between 7 5 and 4 2 ka bp representing a 4 ka time lag after the disappearance of glaciers this suggests that the direct link between the ice retreat and the onset of sackung formation is not obvious even in the case of the once glaciated mountain range although paraglacial stress release is undoubtedly one of the crucial causes of sackung genesis in many mountain regions it is not the only important mechanism therefore despite occurring in numerous de glaciated mountains sackung features cannot be considered as proof of past mountain glaciations e g during analysis of extra terrestrial settings

vertical crustal movement in the boso peninsula south kanto japan as deduced from the adjustment of a geodetic network with signals abstract in the adjustment of a leveling network that is frequently resurveyed we introduce corrections not only to the approximated heights of the stations but also to their rates of vertical movement which are linear over time as an unknown thus we can apply least squares collocation to the problem and have some cases corresponding to the rank deficiency of the design matrix in the observation equation we have applied this method to the study of the vertical crustal deformation in the kanto district particularly to the boso peninsula honshu japan rates of vertical crustal movement and their covariance matrices are deduced for two periods for the kanto district 1 1965 1978 and 2 1978 1989 and for three periods for the boso peninsula 1 1965 1972 2 1973 1976 and 3 1976 1988 the deduced rates range from 10 mm yr to 10 mm yr and their standard deviations amount to 11 mm yr for the kanto district for the boso peninsula they range from 22 mm yr to 6 mm yr and amount to 5 mm yr this peninsula is very close to the convergent plate boundary between the philippine sea plate and south kanto and the results of this analysis reveal the typical fluctuating behavior of the crustal movements associated with the subduction process during the interseismic period the author interprets this episodic crustal movement as being due to intermittent creep dislocation along the deeper part of the interface between the kanto district and the philippine sea plate

analysis of satellite derived landslide at central nepal from 2011 to 2016 practical landslide detection has been a challenging task for decades due to the limitations of algorithms and complicated landslide cases visual interpretation is still one of the most reliable methods for landslide detection owing to the development of machine learning google earth engine platform and free access to landsat series images this paper presents a pixel level landslide detection model based on change detection using the random forest method in nepal from the year 2012 2016 the annual landsat images are synthesized into one image based on a ranking sequence of ndvi normalized differential vegetation index six more indexes and texture information are calculated as features covering water snow and vegetation enhancement dem digital elevation model is used to provide landscape pattern the synthesized features and landsat images of every 2 nearby years and dem are used to detect landslides in the latter year our model achieves an average producer s accuracy of 68 20 and user s accuracy of 77 01 for landslide detection in terms of the 9278 7443 pixel study image through the 5 years moreover based on the landslide detection results we analyzed the landslide event pattern in central nepal from 2012 to 2016 which accords with the actual cases

gneiss domes and orogeny many gneiss domes record positive feedback between decompression and partial melting of orogenic middle crust exhumed orogens are riddled with gneiss domes cored by migmatites that underwent dehydration melting during decompression the decreasing buoyancy associated with increasing melt fraction drives further decompression at near isothermal conditions as the partially molten crust rises diapirically this combination of processes may explain the generation and retention of large volumes of crustally derived melt recorded in many deep seated migmatite terranes and inferred for active orogens in exhumed orogens the signature of the rapid ascent of partially molten crust is a gneiss dome cored by migmatite granite the large volume of material involved in the vertical transfer of partially molten crust indicates that the formation of gneiss domes is an efficient mechanism for heat advection during orogenesis

temporal behavior of deep seated gravitational slope deformations a review abstract deep seated gravitational slope deformations dsgsds are slow moving hillslope scale mass movements featuring characteristic landforms such as double crested ridges and upslope facing scarps that occur in diverse landscapes throughout the world although these deformations have been studied since the 1960s significant insights to the rates of dsgsds have only been gained within the last two decades owing to progress in geochronology remote sensing and instrumental monitoring absolute age and monitoring data indicate that dsgsd movements are observable over long term 102 years and short term future research directions include constraining the lifespan of dsgsds with absolute age dating and precise high resolution monitoring of spatio temporal displacement across dsgsd bodies it is of great importance to include absolute time scales in the numerical models of dsgsds furthermore combining remote sensing techniques such as synthetic aperture radar interferometry with high resolution lidar scanning and near surface geophysics offers a promising toolkit for collecting very detailed and accurate data on the short term deformation rates of dsgsds

a classification of soil microfabrics abstract the definitions of some terms to describe the distribution pattern of micromorphological components are given and discussed five existing schemes for the characterization of related distribution patterns in soil micromorphology are summarized in a table compared and evaluated the replacement of the terms related distribution pattern by microfabric and fabric sequence by fabric groups are suggested a scheme based on existing terminology and augmented with new terms to describe the hitherto neglected poorly structured soils is proposed four fabric groups are drawn from existing terminology namely iunctic and chlamydic for coarse matrix and fragmic and matrigranic for fine matrix fabrics two new fabric groups namely planvic and equanvic are proposed to describe poorly structured soils according to the shapes and volumes of voids the six fabric groups are arranged in a synoptic diagram to illustrate a comprehensive classification of soil microfabrics a dichotomous key to aid fabric identification is provided use of standardized short forms for fabric names is suggested

quaternary glacial history of the central karakoram abstract the quaternary glacial history of the world s highest mountains the central karakoram is examined for the first time using geomorphic mapping of landforms and sediments and 10 be terrestrial cosmogenic nuclide surface exposure dating of boulders on the moraines and glacially eroded surfaces four glacial stages are defined the bunthang glacial stage 0 7 ma the skardu glacial stage marine oxygen isotope stage mis 6 or older the mungo glacial stage mis 2 and the askole glacial stage holocene glaciers advanced several times during each glacial stage these advances are not well defined for the oldest glacial stages but during the mungo and askole glacial stages glacial advances likely occurred at 16 11 13 5 and 0 8 ka the extent of glaciation in this region became increasingly more restricted over time in the braldu and shigar valleys glaciers advanced 150 km during the bunthang and skardu glacial stages while glaciers advanced 80 km beyond their present positions during the mungo glacial stage in contrast glaciers advanced a few kilometers from present ice margins during the askole glacial stage glacier in this region likely respond in a complex fashion to the same forcing that causes changes in northern hemisphere oceans and ice sheets teleconnected via the mid latitude westerlies and also to changes in monsoonal intensity

slope failure and denudation in the western himalaya slope failures glaciers and rivers constitute the three main agents of denudation in the himalaya failure of slopes is strongly controlled by bedrock geology especially at plate terrane boundaries although climatic and seismic controls of failure also occur slope failure complexes in the western himalaya studied for this report include the pakhar kaghan nanga parbat and atabad hunza areas with 23 different slope failures reported within all the complexes quantification of denudation by mass movement requires measurement of volumes and determination of timing of sediment emplacement and removal where possible to obtain better data on recurrence intervals and total geomorphic work performed in formation of the landscape the relation of mass movement to overall denudation by glaciers and rivers and its role in catastrophic floods and debris entrainment is assessed

surface uplift uplift of rocks and exhumation of rocks uplift of the surface of mountain belts requires forces that are comparable in magnitude to those associated with plate motion and therefore determination of rates of surface uplift could provide important information on the dynamics of mountain ranges rates of uplift of the surfaces of mountain ranges have not however been quantified sufficiently well that they provide useful constraints on those processes many reports off surface uplift in mountain ranges are based on mistaking exhumation of rocks or uplift of rocks for surface uplift and provide no information whatsoever on the rates of surface uplift

rapid pliocene exhumation in the karakoram pakistan revealed by fission track thermochronology of the k2 gneiss rapid pliocene denudation in the karakoram pakistan as revealed by fission track dating of rocks from k2 godwin austen was probably caused by tectonic uplift apatite separated from samples collected from elevations of 5300 to 8611 yielded fission track ages of 2 1 0 6 to 4 3 1 4 ma and suggest an initial apparent denudation rate of 3 6 mm yr commencing after 5 ma one zircon separate from 6600 m gave a mean fission track age of 32 6 ma the mid tertiary zircon age delimits the maximum amount of pliocene denudation to 7000 m the total amount of denudation at the present mean surface elevation of 6000 m was estimated to be 6000 m

the sensitivity of dendrogeomorphic approaches to assessing landslide movements abstract an understanding of past landslide behaviour is crucial for the estimation of future landslide activity in this respect methods of absolute dating are frequently used for landslide history assessment dendrogeomorphic tree ring based approaches are standard methods for the spatio temporal reconstruction of landslide activity with annual to even sub annual resolution and timespans of several centuries depending on the tree age nevertheless the verification of the effectiveness sensitivity and precision of these dendrogeomorphic approaches has not been addressed in more detail despite their wide spectrum of limitations this study makes an assessment of tree ring based chronologies of landslides based on a comparison with the independent data of past landslide activity from instrumental monitoring the chronology of past landslide events was created from 528 tree ring series from 132 individuals of norway spruce picea abies l karst growing on a monitored landslide in the outer western carpathians the ond ejnik mt and was expressed as the yearly variation in the standard event response index the landslide was monitored at two sites via technical levelling since 2007 and an automated wire extensometer since 2014 the obtained results show a high sensitivity of reaction wood formation to movements on the order of several mm e g the abrupt acceleration of movements in february 2017 as recorded by the extensometer moreover a one year delay in the growth response to movement occurring in the middle part of the growing season of the previous year was detected this fact fully supports the introduction of the dendrological year to dendrogeomorphic research the partial lack of correspondence between tree ring records and data from more distant monitoring sites suggests the need for separate dendrogeomorphic analyses of the individual homogenous parts of landslide areas finally the use of four instead of two increment cores per tree did not provide any extra event years but increased the values of the event response index of the dated events

himalayan tectonics explained by extrusion of a low viscosity crustal channel coupled to focused surface denudation recent interpretations of himalayan tibetan tectonics have proposed that channel flow in the middle to lower crust can explain outward growth of the tibetan plateau1 2 3 and that ductile extrusion of high grade metamorphic rocks between coeval normal and thrust sense shear zones can explain exhumation of the greater himalayan sequence4 5 6 7 here we use coupled thermal mechanical numerical models to show that these two processes channel flow and ductile extrusion may be dynamically linked through the effects of surface denudation focused at the edge of a plateau that is underlain by low viscosity material our models provide an internally self consistent explanation for many observed features of the himalayan tibetan system8 9 10

timing and periodicity of paraglacial rock slope failures in the scottish highlands abstract many formerly glaciated mountains exhibit a high density of postglacial rock slope failures rsfs in the form of rockslides rock avalanches or deep seated gravitational slope deformations such rsfs are often termed paraglacial as they reflect pre conditioning by glaciation and deglaciation the temporal pattern of paraglacial rsfs is unknown we employ 47 cosmogenic isotope exposure ages obtained for 17 catastrophic rsfs in the scottish highlands to test models of changes in rsf frequency since deglaciation our results show that rsf activity spans almost the entire postglacial period from 17 ka until 1 5 ka and that the periodicity of sampled postglacial rsfs is statistically indistinguishable from a pattern of uniform periodicity 1 ka 1 our data do not conform to proposed models of declining rsf frequency with time elapsed since deglaciation but suggest that the temporal distribution of postglacial rsfs is best described by a combination of rapid response enhanced rsf frequency during or immediately after deglaciation followed by approximately constant periodicity our findings are consistent with near surface fracturing of rock when glacially induced confining stresses are removed causing some failures during or immediately after deglaciation and reducing other slopes to critical conditional stability so that failure is triggered by progressive rock mass weakening or by transient triggering mechanisms neither permafrost degradation thaw of ice in joints nor seismic activity offers a general explanation for triggering scottish rsfs but could be contributory in some cases the quasi constant periodicity inferred for holocene rsfs implies that the probability of rsfs in this seismically quiescent intraplate area has not changed in the past 10 ka and that further though infrequent catastrophic rsfs are likely to occur in the future

catastrophic landslides and their effects on the upper indus streams karakoram himalaya northern pakistan abstract the paper examines the nature and geomorphic influences of deposits from rock avalanches that obstruct rivers most of the 115 rockslide rock avalanche events identified in the karakoram himalaya straddled one or more stream valleys at least 73 of these landslides formerly dammed the indus or its tributaries upstream of the barriers remnants exist of once very extensive lacustrine deposits the stability and long term survival of dams from large rock avalanches is addressed and the reasons for the gradual or phased rather than catastrophic and sudden breaching case histories emphasise the erosional and depositional forms associated with the barriers they are reconstructed in terms of the emplacement and properties of the deposits from rock avalanches and the response of the river to interruption by them these barriers have exerted a substantial control over stream response and development for most of the holocene at least today they are associated with distinctive features of channel form and thalweg river terrace systems intermontane sediment sinks and sources and local erosional forms in bedrock more broadly the landslide barriers have created a naturally fragmented river system deposition and erosion in the lower few tens or hundreds of meters of the upper indus stream valleys have been dominated by epicycles of aggradation trenching and downcutting that mainly reflect the scale timing and history of each barrier the landforms involved are only indirectly related to the late glacial and paraglacial conditions that have hitherto been regarded as the main explanation

contemporary crustal deformations in the izu peninsula honshu japan and acceleration of plate bending in the northernmost part of the philippine sea plate since the beginning of the anomalous vertical crustal movement in the izu peninsul honshu japan many repeated precise levellings have been carried out by the geographical survey institute trilaterations covering the entire izu peninsula have also been carried out by the geographical survey institute a new technique is developed to adjust the results of levellings because they had been carried out for different epochs along each levelling route and because of rapid vertical crustal movements in conventional least squares adjustment of levelling network only corrections to the approximate height are assumed to be unknown while in the present analysis a special model in which rates of vertical deformation at any bench marks are also assumed to be unknown is adopted in addition tidal stations along the coast of the izu peninsula yield the rate of vertical crustal movement from analysis of tidal data independent of levelling data we select several special bench marks in which rates of vertical movement are determined by tidal analysis thereafter special adjustment is applied according to the type of network

mass movement in the himalaya new insights and research directions abstract ongoing studies that relate tectonics to the processes at the surface of earth show that many more sources of information about agents of shallow denudation such as mass movement are required to comprehend the long term erosion that leads to deep denudation over geologic time mass movement in the himalaya is scale dependent from the massive extension of whole mountain ranges gravity tectonics through the sackung failure of single peaks to the smallest slope failures generally denudation of the himalayan orogen begins with slope failure onto glaciers and into river valleys and continues by glacial and fluvial transport the maximum size of stable slopes and mean angles of slope that are produced by these failures are complex and controlled by a variety of factors including mass strength of the rocks stress fields angles of internal friction controlled by rock type cohesion that includes the control of rock temperature bulk unit weight of rock and discontinuities the processes of mass movement in the himalaya have been described many times for the past two centuries recently developments in a variety of fields have been introduced to assess the character of mass movement geomorphometry remote sensing digital elevation models and geographic information system technology are revolutionizing the study of mass movement in the himalaya

timing and features of a late mis 2 rock avalanche in the eastern himalayas constrained by 10be exposure dating abstract we investigate a previously unrecorded rock avalanche deposit yadong rock avalanche that resulted from a major mountain slope failure on the northwest slopes of mt chomo lhari in the eastern himalayas we provide detailed mapping of the yadong rock avalanche and date the rock avalanche using 10be surface exposure dating the 10be exposure ages of six samples suggest that the yadong rock avalanche occurred between 14 2 1 3 13 1 1 3 ka during the bolling allerod ba period the climate was semi arid during the ba period as it is today which suggests that precipitation was unlikely the trigger for this rock avalanche the relatively small paleo glaciers make glacial debuttressing trigger unlikely since the rock scar is situated above the lower permafrost limit degradation of permafrost associated with deglaciation was also unlikely to be the trigger given the rock avalanche is located near the yadong fault which is part of the active yadong gulu rift and the yadong gulu rift has experienced great earthquakes on centennial to millennial timescales we suggest that the most probable trigger for this rock avalanche was a seismic event associated with the yadong fault the result provides evidence for identifying a paleo seismic event occurred during 14 2 1 3 13 1 1 3 ka these findings have important implications for understanding the mechanisms for driving rock avalanches and associated landscape evolution across the himalayas as well as for extending the limited scientifically documented records of major mass movements in the eastern himalayan region

the micromorphology of unconsolidated sediments this paper aims to describe the use of thin sections micromorphology in the sedimentology of unconsolidated sediments it provides examples of the use of thin sections in a variety of sedimentary environments from fault gouge through caves and volcanics to aeolian fluviatile marine periglacial and glacial it demonstrates that in the latter three fields the use of micromorphology is relatively widespread and that in glacial sedimentology it has revolutionised our way of thinking about subglacial sediments although micromorphology has been mainly descriptive so far methods of quantification observations are demonstrated some of the important aspects of micromorphology are its use for microstratigraphy and the possibility of relating observations to documented processes thereby allowing a more robust sedimentological interpretation of modern and ancient sediments

nature and timing of large landslides within an active orogen eastern pamir china abstract large scale landsliding involving 106 m3 in volume is important in landscape development in high mountains to assess the importance of large landslides in high mountains four large landslides bulunkou muztagh taheman and yimake were mapped in the ne chinese pamir at the westernmost end of the himalayan tibetan orogen and dated using 10be terrestrial cosmogenic nuclides the bulunkou landslide at the southernmost end of muji valley is composed of 1 7 107 m3 of landslide debris and has an age of 2 0 0 1 ka the muztagh landslide located on the sw side of the massif muztagh ata is composed of 4 7 108 m3 of debris and has an age of 14 3 0 8 ka the taheman landslide located south of muztagh ata is composed of 2 6 108 m3 of landslide debris and has an age of 6 8 0 2 ka the yimake landslide on the northern frontal range of the pamir at the southwestern end of the tarim basin is composed of 1 4 109 m3 of landslide debris and has an age of 7 1 0 6 ka two other large landslides are present in the region the aerpa aigezi on a tributary of the gez river and the bile jiyi on the yarkand river landslides and are composed of 1 6 107 m3 and 5 2 106 m3 of landslide debris respectively however the aerpa aigezi and bile jiyi landslides were not studied in as much detail or dated because of their inaccessibility given the tectonically active nature of this region with numerous active faults and the morphology of the landslides these landslides were likely triggered by earthquakes however other causes including long term increased precipitation and geologic bedrock structure could be important contributing factors in their formation

a reevaluation of cosmogenic 36cl production rates in terrestrial rocks we have measured 36cl in a suite of 33 rock samples having well constrained exposure histories and ages the 36cl production parameters were estimated by minimizing the squared deviations between the 36cl and independent ages yielding the following production parameters spallation and muon production from ca 2940 200 atoms 36cl mole ca 1 yr 1 spallation from k 6020 400 atoms 36cl mole k 1 yr 1 and neutron production in air 586 40 fast neutrons g air 1 yr 1 the new production constants for spallation on ca and thermal neutron activation are in good agreement with previous results but that for spallation on k is about 50 larger the past decade has seen a rapid growth in the application of terrestrial cosmogenic nuclides produced by cosmic ray particles within rocks at the earth surface nuclear cross sections particularly for reactions initiated by neutrons and muons are not known with sufficient accuracy so production rates for these nuclides must be empirically calibrated using independently dated geological samples direct production estimates for 36cl were first obtained by zreda et al 1991 who measured 36c1 in mineral separates from granitic boulders on moraine crests at chiatovitch creek in the eastern white mountains of california and nevada this data set was the best available at the time but since then several factors have prompted a reevaluation of the 36cl production rates one is that zreda et al 1994 have shown that there can be significant scatter of the cosmogenic ages of individual glacial boulders toward ages younger than that of the moraine due to soil erosion a second factor is that a much wider range of samples is now available for this purpose finally recent theoretical advances in calculating production by thermal neutron absorption liu et al 1994 now permit more realistic calibration of this reaction

cosmogenic chlorine 36 from calcium spallation calcium is a major target element for cosmogenic 36cl production consequently 36cl rapidly reaches detectable levels in minerals such as calcite and calcium feldspar exposed at the earth s surface spallation of calcium isotopes typically accounts for 80 90 of 36cl production in these minerals with subsidiary contributions from negative muon capture by 40ca and thermal neutron capture by 35cl to provide a basis for surface exposure dating we have calibrated cosmogenic 36cl production in calcium feldspar from the 17 300 year old tabernacle hill basalt at an altitude of 1445 m and an effective geomagnetic latitude of 40 9 the calcium spallation rate is 152 11 atoms g ca 1 a 1 the corresponding rate at sea level and high latitude is estimated at 48 8 3 4 atoms g ca 1 a 1 the muon capture rate used to derive these values is 8 8 2 2 atoms g ca 1 a 1 at the tabernacle hill site scaled from a value of 4 8 1 2 atoms g ca 1 a 1 at sea level and high latitude the calcium spallation rate determined in this study is in excellent agreement with previous whole rock calibration measurements at tabernacle hill when these are recalculated with respect to the absolute timescale the calibration of 36c1 production from calcium underpins development of an exposure dating technique for calcite due to its high calcium content the 36cl production rate in calcite is higher than in any other common rock forming mineral measurement of 36cl in calcite with an accelerator mass spectrometric detection limit of 5 103 atoms per gram allows dating of limestone surfaces exposed for periods ranging from 102 106 years alternatively erosion rates from less than 1 to greater than 1000 m per year can be determined in the case of eroding karst surfaces though the 36cl production rate is lower in calcium feldspar than in calcite measurements on this mineral will provide a useful means of dating young basalt lavas