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

a review of glacial geomorphology and chronology in northern spain timing and regional variability during the last glacial cycle abstract in this paper we synthesize the research in glacial geomorphology and geochronology in northern spain with special attention to the evidence of local glacier maximum extent earlier than the global lgm of mis 2 18 21 ka bp more accurate models of glacier evolution have been defined based on limnogeological geochronological and geomorphological data in the pyrenees osl optically stimulated luminescence surface exposure and radiocarbon dating techniques have identified end moraines and fluvial terraces corresponding to mis 6 about 170 ka and even to mis 8 about 260 ka and also established the timing of the last local glacial maxima as prior to global lgm mis 4 ca 50 70 ka during the global lgm a smaller re advance occurred but glaciers reached different extents in the central and the eastern pyrenees in nw iberia radiocarbon and osl techniques point to local glacial maximum prior to ca 26 ka 38 ka and probably synchronous with 45 ka although some bias might have been introduced by the dating procedures this review demonstrates that in both regions the local maximum extent occurred prior to the global lgm the asynchronies between the glacial maxima chronologies in the different mountain ranges of northern spain suggest that local climate factors exert a strong control on mountain glacier dynamics

chronological and geomorphological investigation of fossil debris covered glaciers in relation to deglaciation processes a case study in the sierra de la demanda northern spain abstract in this study fossil debris covered glaciers are investigated and dated in the sierra de la demanda northern spain they are located in glacial valleys of approximately 1 km in length where several moraines represent distinct phases of the deglaciation period several boulders in the moraines and fossil debris covered glaciers were selected for analysis of 10 be surface exposure dating a minimum age of 17 8 2 2 ka was obtained for the outermost moraine in the san lorenzo cirque and was attributed to the global last glacial maximum lgm or earlier glacial stages based on deglaciation dates determined in other mountain areas of northern spain the youngest moraines were dated to approximately 16 7 1 4 ka and hence correspond to the gs 2a stadial oldest dryas given that the debris covered glaciers fossilize intermediate moraines it was deduced that they developed between the lgm and the oldest dryas coinciding with a period of extensive deglaciation during this deglaciation phase the cirque headwalls likely discharged large quantities of boulders and blocks that covered the residual ice masses the resulting debris covered glaciers evolved slowly because the debris mantle preserved the ice core from rapid ablation and consequently they remained active until the end of the late glacial or the beginning of the holocene for the san lorenzo cirque and the holocene thermal maximum for the mencilla cirque the north facing part of the mencilla cirque ensured longer preservation of the ice core

seismic amplitude tomography for crustal attenuation beneath china summary amplitude tomography reconstructs seismic attenuation directly from recorded wave amplitudes we have applied the tomography to amplitude data reported in the annual bulletin of chinese earthquakes and interpreted the regionally varying crustal attenuation in terms of tectonics the seismic amplitudes were originally recorded for determining the m l and m s magnitudes they generally correspond to the maximum amplitudes of the horizontal components of the short period s waves and intermediate period rayleigh waves both sets of measurements are sensitive to crustal structure the peak amplitudes from m l amplitudes spread spherically with significant dispersion and scattering m s amplitudes show cylindrical spreading with little dispersion average crustal q values for attenuation at 1 hz are 737 and 505 for m l and m s respectively with substantial regional variations frequency dependence in the attenuation is also indicated regions with the lowest attenuation high q values are beneath the south china block sichuan basin ordos platform the daxinganling and the korea craton these tend to be tectonically inactive regions which are generally dominated by intrusive and cratonic rocks in the upper crust regions with the highest attenuation low q values are beneath bohai basin yunnan eastern songpan ganzi terrain margins of the ordos platform and the qilian shan these are predominantly active basins grabens and fold belts the continental margin also highly attenuates both s and surface waves

postglacial topographic evolution of glaciated valleys a stochastic landscape evolution model the retreat of valley glaciers has a dramatic effect on the stability of glaciated valleys and exerts a prolonged influence on the subsequent fluvial sediment transport regime we have studied the evolution of an idealized glaciated valley during the period following retreat of ice using a numerical model the model incorporates a stochastic process to represent deepseated landsliding non linear diffusion to represent shallow landsliding and an approximation of the bagnold relation to represent fluvial sediment transport it was calibrated using field data from several recent surveys within british columbia canada we present ensemble model results and compare them with results from a deterministic linear diffusion model to show that explicit representation of large landslides is necessary to reproduce the morphology and channel network structure of a typical postglacial valley our model predicts a rapid rate of fluvial sediment transport following deglaciation with a subsequent gradual decline similar to that inferred for holocene time we also describe how changes in the model parameters affect the estimated magnitude and duration of the paraglacial sediment pulse

ultra rapid landscape response and sediment yield following glacier retreat icy bay southern alaska abstract glacial retreat and opening of taan fjord an arm of icy bay alaska in the last two decades drove a base level fall of 400 m at the outlets of four tributary valleys in the region of the current tyndall glacier terminus response in the tributary valleys to this base level fall includes evacuation of stored sediment incision of slot gorges into bedrock and landsliding on valley walls fluvial transfer of eroded bedrock glacial deposits and stored nonglacial fluvial deposits after 1983 resulted in progradation of fan deltas toward the fjord centerline at the outlet of each of the four catchments in the largest nonglacial tributary valley 0 08 km 3 8 of the 0 59 km 3 of 500 m thick stored fluvial and colluvial deposits has been transferred to the adjacent fjord a percentage of the fjord sedimentation in the last two decades thus includes material eroded from bedrock and stored in the landscape during the previous glacial expansions distal deltaic deposits extend across the fjord floor and likely interfinger with distal proglacial deltaic deposits sourced from the tyndall glacier a paraglacial landscape response such as the one exhibited in upper taan fjord where sediment delivery to fjords from tributary sources in synchrony with sediment produced by primary bedrock erosion by glaciers helps to explain the order of magnitude discrepancy between sediment yields from alaskan tidewater glaciers on 10 0 to 10 2 year timescales and sediment yields and exhumation rates on 10 4 to 10 6 year timescales

paraglacial gullying of sediment mantled slopes a case study of colletthogda kongsfjorden area west spitsbergen svalbard this paper evaluates the paraglacial evolution of a sediment mantled slope in a polar maritime environment the intensity of paraglacial processes is estimated through quantifi cation of erosion and dating of fi eld sectors with the help of photographic archives gully erosion has been estimated using morphometric parameters and by surveys of vegetation cover the rapid melting of dead ice cores controls gully formation this leads to slope form modifi cation gully profi le gradients are reduced from a mean of 35 to a mean ranging between 10 and 15 profi le evolution results from the collapse of glacier lateral moraine all data mean slope angle of individual gullies frequency distribution of slope angles fractional distance to the apex gullying index volume of debris mobilized vertical erosion rate tend to increase with increasing deglaciation age and the duration of paraglacial activity vegetation colonization is a response to stabilization of the ground surface and the drying up of the ground surface due to dead ice melting the full sequence of paraglacial slope adjustment gully incision stabilization may occur rapidly at the study site i e within two decades finally a lateral morphogenic sequence is proposed showing the importance of paraglacial processes at the onset of the deglaciation

timing of last deglaciation in the cantabrian mountains iberian peninsula north atlantic region based on in situ produced 10 be exposure dating abstract the last glacial termination led to major changes in ice sheet coverage that disrupted global patterns of atmosphere and ocean circulation paleoclimate records from iberia suggest that westerly episodes played a key role in driving heterogeneous climate in the north atlantic region we used 10be cosmic ray exposure cre dating to explore the glacier response of small mountain glaciers ca 5 km2 that developed on the northern slope of the cantabrian mountains iberian peninsula an area directly under the influence of the atlantic westerly winds we analyzed twenty boulders from three moraines and one rock glacier arranged as a recessional sequence preserved between 1150 and 1540 m above sea level a s l in the monasterio valley redes natural park results complement previous chronologic data based on radiocarbon and optically stimulated luminescence from the monasterio valley which suggest a local glacial maximum local gm prior to 33 ka bp and a long standing glacier advance at 24 ka coeval to the global last glacial maximum lgm resultant 10be cre ages suggest a progressive retreat and thinning of the monasterio glacier over the time interval 18 1 16 7 ka this response is coeval with the heinrich stadial 1 an extremely cold and dry climate episode initiated by a weakening of the atlantic meridional overturning circulation amoc glacier recession continued through the bolling allerod period as indicate the minimum exposure ages obtained from a cirque moraine and a rock glacier nested within this moraine which yielded ages of 14 0 and 13 0 ka respectively together they suggest that the monasterio glacier experienced a gradual transition from glacier to rock glacier activity as the amoc started to strengthen again glacial evidence ascribable to the younger dryas cooling was not dated in the monasterio valley but might have occurred at higher elevations than evidence dated in this work the evolution of former glaciers documented in the monasterio valley seems consistent with previous 10be chronologies reported in other mountain ranges of the iberian peninsula which have been recalculated according to a common production rate and scaling scheme however the re evaluation of published 10be chronologies has highlighted the fact that glacial evidence previously ascribed to the younger dryas might be more limited than previously thought and the need for additional studies to characterized the extent of glaciers during the younger dryas cooling

brunhes matuyama boundary 790 k y date consistent with odp leg 130 oxygen isotope records based on fit to milankovitch template the age of the brunhes matuyama boundary until recently taken as 730 k y in standard time scales for the quaternary e g imbrie et al 1984 prell et al 1986 and in ocean drilling program results kroenke et al 1991 shackleton et al 1992 has been revised to between 780 k y and 790 k y based on both orbital tuning of oxygen isotope data e g shackleton et al 1990 and on new 40ar 39ar dates on volcanic rocks e g baksi et al 1992 we apply the revised chronology to an oxygen isotope record for ontong java plateau odp leg 130 western equatorial pacific using this time scale we find excellent agreement between the record and a template based on orbital forcing the equation for the template is where the change in ice mass is given as the difference between constant ice growth igr and variable amounts of melting melting depends on summer insolation at 65 n ins the current ice mass present ice and the average ice mass mem over a given time interval l the memory base l and the exponents are adjusted for best fit the fit to the relevant portion of the record yields an age of 790 6 k y for the brunhes matuyama boundary the age assignment is robust relative to substantial changes in parameter settings

seismic imaging of the crust and upper mantle using regularized joint receiver functions frequency wave number filtering and multimode kirchhoff migration 1 receiver functions provide an indispensable tool for producing discontinuity images of the crust and upper mantle from teleseismic earthquake arrivals however image quality can be significantly compromised by instabilities inherent in the deconvolution process and by irregularities in data coverage driven by source and or receiver geometries we present receiver function estimation and prestack migration techniques which both reduce receiver function deconvolution instability and produce regularized multimode receiver function images the receiver function estimation technique exploits frequency wave number filtering methods using frequency pseudowave number domain filtering of gathers to enhance arrivals with consistent moveout characteristics synthetic tests confirm robust recovery of features in the presence of high noise levels to process regularized receiver functions into accurate images of the subsurface seismic scattering potential we employ a regularized kirchhoff migration that migrates both direct and reverberated p to s converted modes to their correct subsurface locations the subsequent images can be stacked to mute mismigrated modes synthetic studies and model resolution tests demonstrate that this methodology is well suited to irregularly spaced stations and uneven data coverage and does not require the recording of a single earthquake at multiple stations

applying the aabr method to reconstruct equilibrium line altitudes from the last glacial maximum in the cantabrian mountains sw europe abstract several glaciers developed in the cantabrian mountains nw spain during the last glacial maximum lgm in the last 15 years several studies of glacial geomorphology have increased the knowledge about the limits of the glaciation but little data are available about many valleys especially on the northern slope due to extensive postglacial erosion in this study we apply the aabr method to reconstruct palaeo equilibrium line altitudes elas in eleven palaeo glaciers that are considered to be representative of the different areas of the range to reduce the ambiguity in the palaeo ela values caused by local factors we analysed medium and large glaciers 4 7 to 65 5 km2 except for the sil complex glacier which was the largest glacier in northwestern spain 445 km2 the palaeo elas during the local lgm ranged between 1000 and 2000 m and had a similar pattern to the present day winter precipitation and summer temperatures

rockfall talus slopes and associated talus foot features in the glaciated uplands of great britain and ireland periglacial paraglacial or composite landforms

paraglacial response of steep sediment mantled slopes to post little ice age glacier recession in the central swiss alps this research assesses the morphological consequences of recent post little ice age paraglacial reworking of valley side sediment mantles in the european alps it aims to identify the extent and conditioning factors of slope adjustment at sites in the swiss alps model the temporal pattern and assess the rates of sediment reworking involved gully systems have cut into steep high level lateral moraines and debris cones have accumulated downslope debris flow is the dominant agent of sediment transfer factors controlling the extent of this activity include moraine slope gradient relief and moisture availability gullies appear to have reached their maximum dimensions within ca 50 yr of deglaciation after which gully relief is reduced by removal of inter gully slopes and gully infilling within 80 140 yr on the most recently deglaciated terrain minimum erosion rates average ca 95 mm yr 1 since gully initiation greatly exceeding normal erosion rates in other environments mean annual accumulation of a single debris cone since ice retreat was calculated to be ca 30 mm yr 1 implications of these findings are applied to patterns of paraglacial sediment mantled slope adjustment conceptualising paraglacial landscape response in terms of a sediment release exhaustion model and paraglacial landform succession copyright 2005 john wiley sons ltd

deglaciation in the central pyrenees during the pleistocene holocene transition timing and geomorphological significance abstract in this study we document deglaciation in a sector of the southern central pyrenees the panticosa massif and the upper gallego and ossau valleys using cosmic ray exposure cre dating methods which were applied to samples from high altitude polished rock steps and rock glacier boulders the obtained cre dates show a coherent spatial distribution and confirm results previously obtained in this study area thus demonstrating the reliability and robustness of the method the results of analyses based on two distinct isotopes 10 be and 36 cl are consistent although the error is higher for results based on the 36 cl isotope the study provides evidence for ice extent in the high gallego valley during the oldest dryas with glacial advance until the bottom of the valleys although the main glacier tongues remained disconnected from each other during this period the extent of glacier advance was directly related to the elevation of the associated summits the younger dryas glaciers were constrained to cirques or very short ice tongues and dating of the polished rock steps indicates that the ice masses were present until the first millennium of the holocene the brazato rock glacier developed at the beginning of the holocene and remained active until the holocene thermal optimum because of the protective effect of large masses of blocks and boulders

the effect of topography latitude and lithology on rock glacier distribution in the lemhi range central idaho usa abstract statistical analysis of rock glaciers in the lemhi range demonstrates that their development and preservation is controlled primarily by annual insolation and lithology we inspected 171 alpine valleys in the lemhi range using optical remote sensing techniques digital topographic analysis and field examination in those valleys we identified 48 rock glaciers and examined them for lichen cover evidence of ice presence specific evidence of movement and distinctive morphological features in addition to recording the presence or absence of a rock glacier in each alpine valley existing rock glaciers were classified according to their morphology factors such as topographic shading lithology relief aspect and elevation determine the development and preservation of rock glaciers analysis of these factors in the lemhi range shows that elevation 2600 m a north facing aspect 300 60 and multivariate statistical analysis of controlling parameters demonstrates that annual insolation and latitude influence rock glacier occurrence most strongly whereas duration of insolation is a logical controlling factor latitude is more enigmatic additional statistical analysis indicates that the latitude factor is likely a reflection of lithologic changes with latitude along the range lithology may affect rock glacier distribution through its effects on hydrology or air ventilation moreover statistical analysis shows that rock glacier occurrence correlates with protalus lobe occurrence suggesting that protalus lobes play a role in the genesis of rock glaciers in the lemhi range separate analysis of the classification systems shows that each morphologic class inferred to correlate with rock glacier activity is statistically significant and distinguishable from other classes in addition to the effect of insolation statistical analysis of the classification system also shows that latitude influences distribution of existing rock glacier classes independent of lithology

an early advance of glaciers on mount akdag sw turkey before the global last glacial maximum insights from cosmogenic nuclides and glacier modeling abstract for the first time in turkey we report an early advance of glaciers before the broadly defined global last glacial maximum lgm forty one moraine boulders from three glacial valleys on mount akdag 36 54 n 29 57 e 3016 m southwest coast of turkey were dated with cosmogenic 36 cl valleys on the north side of the mountain were filled with few km long glaciers that terminated at elevations of about 2000 m above sea level a s l the pre lgm glaciations reached their maximum positions 2150 m a s l by 35 1 2 5 ka ago 1 ka 1000 calendar years the glaciers readvanced during the global lgm and reached their farthest locations 2050 m a s l by around 21 7 1 2 ka ago later glaciers retreated and shortly stabilized during the lateglacial at around 15 1 0 9 ka ago using the glacier modeling and paleoclimate proxies from the eastern mediterranean we estimated that if temperatures during the lgm were 8 11 c colder than modern which is suggested by paleotemperature proxies from the region precipitation was up to two times more than that of today previous estimates on southwest coast of turkey indicate a similar precipitation value while central turkey requires drier conditions implying regional heterogeneity on lgm climates in turkey

relict rock glaciers as indicators of mediterranean palaeoclimate during the last glacial maximum late wurmian in northwest greece relict rock glaciers have been identified and mapped in the high cirques of mount tymphi in the pindus mountains of northwest greece they are periglacial forms and represent the most recent cold stage landforms in an area that displays widespread evidence of pleistocene glaciation it is likely that these features formed during the last glacial maximum late wurmian as talus rock glaciers and beneath small cirque glaciers as debris rock glaciers comparisons with modern rock glacier climate relationships suggests mean annual temperatures of ca 8 9 c lower than present at their time of formation this temperature reconstruction is in good agreement with recent palaeoclimatic reconstructions for the northern mediterranean based on a general circulation model moreover as rock glaciers are typical of cold and relatively dry mountain regions their presence is consistent with palaeobotanical and lake level data suggesting a cold and relatively dry climate for the last glacial maximum in greece however the presence of small cirque glaciers above some rock glaciers suggests that although precipitation must have been low enough to preclude glacier extension down to lower altitudes it was not so low as to inhibit glacier formation entirely copyright 2003 john wiley sons ltd

crustal structure beneath the weihe graben in central china evidence for the tectonic regime transformation in the cenozoic abstract in central china weihe graben wg and its adjacent area suffered intensive compressional tectonics in the paleozoic and the mesozoic then this region was dominated by extensional tectonics due to the far field effect of the india eurasia collision in the cenozoic we deployed a portable broad band seismic array in this region to investigate the crustal structure by using receiver functions integrated with regional geophysical and geological characteristics the analysis of the receiver functions reveals that the moho is 32 37 km 25 41 km and 41 km depth beneath the northern qinling terrane the wg and the southern margin of the ordos block respectively the moho depth increases beneath the southern boundary of the wg while decreases 10 15 km beneath the northern boundary of the wg the moho discontinuity beneath the wg is not a fully mirror image of the crystalline basement because the thickest sediments 10 km is in the south of the wg the crustal structure in this region reveals how the crust responds to the tectonic regime transformation the effect of the cenozoic crustal extension was top down however the cenozoic crustal extension has limited effect on the moho deformation we suggested that the compressional tectonics before the cenozoic dominated the lateral variation of the moho

large contrasts in crustal structure and composition between the ordos plateau and the ne tibetan plateau from receiver function analysis article i nfo article history we analyzed thousands of receiver function data recorded by 154 national and regional seismic stations to study the crustal structure beneath the ordos plateau and the ne margin of the tibetan plateau moho depth and average crustal vp vs ratio were measured at each station the ordos plateau and the trans north china orogen east of the ordos are underlain by a moderately thick crust of 42 km the weihe graben lying at the southern edge of the ordos plateau has a thin crust of 30 km while its southern neighbor the qinling orogenic belt shows a thick crust extending to as much as 45 km deep the moho depth beneath the ne margin of the tibetan plateau varies from 55 to 65 km we found a remarkable contrast between the tibetan and ordos plateaus in the measured poisson s ratio the ordos plateau is featured by a high poisson s ratio while the tibetan margin has a very low poisson s ratio in general mafic lower crustal rocks have a higher poisson s ratio than felsic ones the measured low poisson s ratio beneath the ne margin of the tibetan plateau thus indicates that the crustal column beneath the margin is rather felsic which seems to be inconsistent with a scenario of an inflated crust due to extrusion of lower crust material from the tibetan plateau to the margin

beyond debuttressing mechanics of paraglacial rock slope damage during repeat glacial cycles cycles of glaciation impose mechanical stresses on underlying bedrock as glaciers advance erode and retreat fracture initiation and propagation constitute rock mass damage and act as preparatory factors for slope failures however the mechanics of paraglacial rock slope damage remain poorly characterized using conceptual numerical models closely based on the aletsch glacier region of switzerland we explore how in situ stress changes associated with fluctuating ice thickness can drive progressive rock mass failure preparing future slope instabilities our simulations reveal that glacial cycles as purely mechanical loading and unloading phenomena produce relatively limited new damage however ice fluctuations can increase the criticality of fractures in adjacent slopes which may in turn increase the efficacy of fatigue processes bedrock erosion during glaciation promotes significant new damage during first deglaciation an already weakened rock slope is more susceptible to damage from glacier loading and unloading and may fail completely we find that damage kinematics are controlled by discontinuity geometry and the relative position of the glacier ice advance and retreat both generate damage we correlate model results with mapped landslides around the great aletsch glacier our result that most damage occurs during first deglaciation agrees with the relative age of the majority of identified landslides the kinematics and dimensions of a slope failure produced in our models are also in good agreement with characteristics of instabilities observed in the field our results extend simplified assumptions of glacial debuttressing demonstrating in detail how cycles of ice loading erosion and unloading drive paraglacial rock slope damage

chronology of glaciations in the cantabrian mountains nw iberia during the last glacial cycle based on in situ produced 10be abstract the mountain ranges of the iberian peninsula preserve a valuable record of past glaciations that may help reconstruct past atmospheric circulation patterns in response to cooling events in the north atlantic ocean available chronologies for the glacial record of the cantabrian mountains which are mainly based on radiocarbon and luminescence dating of glacial related sediments suggest that glaciers recorded their glacial maximum gm during mis 3 and experienced a later last glacial maximum lgm advance this lgm extent is not established yet preventing a fair correlation with available cosmic ray exposure cre based chronologies for the glacial record of the pyrenees and the sistema central we present a glacial reconstruction and a 10 be cre chronology for the porma valley in the southern slope of the central cantabrian mountains glacial evidence at the lowest altitudes correspond to erratic boulders and composite moraines whose minimum 10 be cre age of 113 9 7 1 ka suggests that glaciers were at their maximum extent during mis 5d most likely in response to the minima in summertime insolation of the last glacial cycle recessional moraines preserved within the glacial maximum limits allow the assessment of subsequent glacier advances or stagnations the most remarkable advance took place prior to 55 7 4 0 ka probably at the end of mis 4 consistently with minimum radiocarbon ages previously reported for lacustrine glacial related deposits in the cantabrian mountains a limited number of 10 be cre ages from a composite moraine suggest a possible advance of the porma glacier coeval with the global lgm the glacier front attributed to the lgm would be placed within the margins of the previous gm like in the western pyrenees erratic boulders perched on an ice moulded bedrock surface provided a mean 10 be cre age of 17 7 1 0 ka suggesting that part of the recessional moraine sequence corresponds to minor advances or stagnations of the glacier fronts during the lateglacial period this recessional response is consistent with deglacial chronologies previously established in the pyrenees and the sistema central and correlates with the coldest and driest conditions of mis 2 according to lacustrine records finally a relict rock glacier provided a mean 10 be cre age of 15 7 0 8 ka for movement cessation of its toe indicating that periglacial conditions prevailed at least until the end of heinrich stadial 1 mystery interval

shear wave splitting in the southern margin of the ordos block north china 1 the southern margin of the ordos block in north china marks the transition from a stable cratonic block to active transextensional deformation in the weihe graben driven by the northeastward expansion of the tibet plateau we deployed 29 portable digital stations across this boundary and studied the upper mantle anisotropy using sks splitting the anisotropy is weak t 0 5 s at stations within the ordos block and in the north weihe graben but strong t 1 23 0 39 s in the south weihe graben and qinling orogen further south the directions of the fast s wave are 98 7 subparallel to the orientations of surface structures and the gps site velocities relative to stable asian continent we suggest that this e w oriented anisotropy is the result of both the collision between the north and south china blocks in the mesozoic and the eastward upper mantle flow driven by the indo asian collision

oblique stepwise rise and growth of the tibet plateau two end member models of how the high elevations in tibet formed are i continuous thickening and widespread viscous flow of the crust and mantle of the entire plateau and ii time dependent localized shear between coherent lithospheric blocks recent studies of cenozoic deformation magmatism and seismic structure lend support to the latter since india collided with asia 55 million years ago the rise of the high tibetan plateau likely occurred in three main steps by successive growth and uplift of 300 to 500 kilometer wide crustal thrust wedges the crust thickened while the mantle decoupled beneath gently dipping shear zones did not sediment infilling bathtub like of dammed intermontane basins formed flat high plains at each step the existence of magmatic belts younging northward implies that slabs of asian mantle subducted one after another under ranges north of the himalayas subduction was oblique and accompanied by extrusion along the left lateral strike slip faults that slice tibet s east side these mechanisms akin to plate tectonics hidden by thickening crust with slip partitioning account for the dominant growth of the tibet plateau toward the east and northeast

paraglacial landform assemblages in the hindukush and karakoram mountains abstract the paper focuses on the evolution of debris landforms in subtropical high mountain areas the karakoram and hindukush mountains are characterized by their high volume and variety of debris accumulations the valley flanks are coated by unconsolidated debris slopes up to 1000 m in height the valley floors are occupied by expansive debris flow cones and alluvial fans with escarpment heights of over 100 m the field investigations in over twenty valleys showed that the major part of those landforms is governed by the late and post glacial glaciation history a key role in this glacially controlled landscape system is played by the slope moraines which cover the valley flanks up to several hundred meters above the valley floor the secondary debris supply by resedimentation processes of moraine material and glacially induced rock failures exceed by far the primary debris production due to weathering processes landforms which have been formerly classified as periglacial talus cones rather can be considered as glacial or glacially controlled landforms the identified paraglacial landforms can serve as useful palaeoclimatic indicators for the ice age reconstruction

geotechnical controls on a steep lateral moraine undergoing paraglacial slope adjustment original article can be found at http sp lyellcollection org copyright geological society

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

3 d lithospheric structure beneath southern tibet from rayleigh wave tomography with a 2 d seismic array summary a 3 d shear wave velocity model has been established for the lithosphere of southern tibet through rayleigh wave tomography the teleseismic data are acquired from a 2 d seismic array selected out of the second phase of the hi climb project we first inverted for a 2 d phase velocity model using two plane wave tomography approach and then inverted for the 3 d shear wave velocity model with the 2 d phase velocity model and the map of crustal thickness derived from receiver functions the results reveal a pervasive low velocity anomaly in the middle crust of the lhasa block we interpret this low velocity anomaly as the presence of wholesale mid crustal channel flow prominent low velocity anomalies from the lower crust to the mantle lithosphere are observed along the north south trending rifts the tangra yum co rift and the pumqu xianza rift we propose a possible scenario for the formation of these rifts the entire lithosphere is involved in the early stage rifting while the late stage rifting is restricted in the upper crust in the non rift regions a slab like high velocity anomaly is traced beneath both the himalayas and lhasa block combining all the observations we suggest that the central part of southern tibet is currently underlain by the broken indian lower crust and mantle lithosphere

glaciokarst landforms and processes of the southern dinaric alps glaciokarst is a landscape which combines karst features and hydrology as well as inherited glacial features it is a result of glaciation upon a karst geomorphological system the relationship between glaciers and karst is rather poorly known and inadequately recognized this research focuses on three distinct karst areas along the adriatic coast in the southern dinaric alps that were affected by the quaternary glaciations an insight into specific glaciokarst processes and surface features was provided through the study of the areas of the lovcen orjen and vele mountains a glaciokarst geomorphology is in general well preserved due to the prevailing vertically oriented chemical denudation following de glaciation and almost the entire absence of other surface processes typical glacial erosional features are combined by a variety of depressions which are the result of a karstic drainage of sub glacial waters the majority of glacial deposits occur as extensive lateral terminal moraine complexes which are often dissected by smaller breach lobe moraines on the external side of the ridge those moraine complexes are likely to be a product of several glacial events which is supported by complex depositional structures according to the type of glacial depositional features the glaciers in the study areas were likely to have characteristics of moraine dammed glaciers due to vertical drainage ice marginal fluvial processes were unable to evacuate sediment fluvial transport between glacial and pro glacial systems in karst areas is inefficient nevertheless some sediment from the glacier margin is washed away by the pro glacial streams filling the karst depressions and forming piedmont type poljes copyright 2015 john wiley sons ltd

evaluating debris slide occurrence using digital data paraglacial activity in chilliwack valley british columbia debris sliding is one of the most important processes acting to transport sediment within mountainous regions detailed study of debris slide activity at the basin scale typically involves landslide inventories generated from aerial photographs however it has been shown that some types of rapid mass movement can be accurately identified using a combination of high resolution satellite imagery and digital elevation data this approach is beneficial as the digital products allow for a more accurate and efficient data throughput into various types of geomorphic analysis here we demonstrate the use of an automated inventory in the geomorphometric evaluation of debris slide initiation for the chilliwack basin british columbia canada our results indicate that the occurrence of debris sliding is primarily determined by topographical controls for basins that are in equilibrium with the existing climate the frequency of debris sliding should demonstrate a strong relationship to bedrock geology as the production of unconsolidated materials available for failure is a function of weathering rates under these conditions the lack of bedrock control within the chilliwack basin suggests a state of paraglacial relaxation wherein glacial deposits dominate the sediment cascade within the area therefore topographic parameters can be used to discriminate the location of metastable slopes where debris slide erosion will be active the use of digital data in the characterization of debris slide occurrence would seem to be a viable alternative to the more traditional methods

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

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

palaeoenvironmental studies in nw iberia cantabrian range vegetation history and synthetic approach of the last deglaciation phases in the western mediterranean abstract at the north western limit of the mediterranean basin in the mediterranean oceanic transition zone the multidisciplinary study of two palaeolakes villaseca and la mata province of leon provides data on the last deglaciation the juxtaglacial lakes were formed during a deglaciation phase of the last cold stage weichselian wurm estimated from the regional and pyrenean chronological data between circa 48 ka and 32 ka ka 1000 years ago their drainage occurred circa 17 ka and 15 ka respectively during the definitive glacial retreat phases these results provide evidence for a glacial maximum extension preceding the global last glacial maximum lgm and an early deglaciation comparisons with the pyrenean data show that in the most important glacial basins of the pyrenean cantabrian range glaciers were still present at middle elevation circa 18 20 ka the final deglaciation did not happen until around 16 ka during the period 48 13 3 ka along the pyrenean cantabrian range three stages can be distinguished in the deglacial processes between circa 48 and 32 ka the deglacial retreats were contemporaneous with d o events 12 to 6 between circa 32 ka and 18 ka major sedimentary modifications were rare two of them are synchronous with d o 4 and 3 a glacial readvance also occurred during this period along the pyrenean cantabrian range between 18 and 17 ka major sedimentary changes and an increase in the 18o records of the ngrip ice core record are synchronous between 15 and 13 3 ka glacial retreats and sedimentary changes are synchronous with the climatic improvement observed from the end of the oldest dryas to the end of the bolling allerod period these correspondencies suggest relationships between the deglacial processes in the western mediterranean and the palaeoenvironmental events in the north atlantic region during the last glacial interglacial transition during the full glacial period the pollen data indicates dominant steppic environments the oldest dryas was not a constant cooling phase and from around 15 5 ka the pollen data indicates a slight warming during the holocene until circa 2040 cal bp mixed oak forests developed and pine was a prominent component of the cantabrian landscape then the forests were destroyed due to mining agriculture and fire and this favoured the extension of heathland

crustal structure of the northeastern margin of the tibetan plateau from the songpan ganzi terrane to the ordos basin abstract the 1000 km long darlag lanzhou jingbian seismic refraction profile is located in the ne margin of the tibetan plateau this profile crosses the northern songpan ganzi terrane the qinling qilian fold system the haiyuan arcuate tectonic region and the stable ordos basin the p wave and s wave velocity structure and poisson s ratios reveal many significant characteristics in the profile the crustal thickness increases from northeast to southwest the average crustal thickness observed increases from 42 km in the ordos basin to 63 km in the songpan ganzi terrane the crust becomes obviously thicker south of the haiyuan fault and beneath the west qinlin shan the crustal velocities have significant variations along the profile the average p wave velocities for the crystalline crust vary between 6 3 and 6 4 km s beneath the songpan ganzi terrane west qinling shan and haiyuan arcuate tectonic region p wave velocities of 6 3 km s are 0 15 km s lower than the worldwide average of 6 45 km s north of the kunlun fault with exclusion of the haiyuan arcuate tectonic region the average p wave velocity is 6 4 km s and only 0 5 km s lower than the worldwide average a combination of the p wave velocity and poisson s ratio suggests that the crust is dominantly felsic in composition with an intermediate composition at the base a mafic lower crust is absent in the ne margin of the tibetan plateau from the songpan ganzi terrane to the ordos basin there are low velocity zones in the west qinling shan and the haiyuan arcuate tectonic region the low velocity zones have low s wave velocities and high poisson s ratios so it is possible these zones are due to partial melting the crust is divided into two layers the upper and the lower crust with crustal thickening mainly in the lower crust as the ne tibetan plateau is approached the results in the study show that the thickness of the lower crust increases from 22 to 38 km as the crustal thickness increases from 42 km in the ordos basin to 63 km in the songpan ganzi terrane south of the kunlun fault both the conrad discontinuity and moho in the west qinling shan and in the haiyuan arcuate tectonic region are laminated interfaces implying intense tectonic activity the arcuate faults and large earthquakes in the haiyuan arcuate tectonic region are the result of interaction between the tibetan plateau and the sino korean and gobi ala shan platforms

slope instability in relation to glacial debuttressing in alpine areas upper durance catchment southeastern france evidence from field data and 10be cosmic ray exposure ages the upper durance catchment is an area prone to rock slope failures such failures reflect the combination of high relief litho structural controls and paraglacial stress release the aim of this study is to determine the role of deglacial unloading and resulting paraglacial stress release in conditioning or triggering slope failure former dimensions of the durance glacier are reconstructed then combined with digital elevation model data in a raster geographic information system to quantify the spatial pattern of stresses associated with glacial loading at the last glacial maximum preliminary calculations suggest that major rock falls and rock avalanches are associated with areas subject to the highest decompression stresses focus on two case studies allows the consequences of paraglacial stress release on slope instability to be evaluated description of slope failure runout deposits allows reconstruction of the nature of slope failure surface exposure dates based on concentration of cosmogenic 10be allows the timing of both deglaciation and that of post glacial rock slope failures to be established it is shown that rock slope failures are concentrated on lower valley side slopes within the area occupied by ice at the last glacial maximum and that their locations coincide with zones of inferred high glacial loading stress consistent with interpretation of both bedrock disruption and large scale rock slope failures as paraglacial phenomena induced by stress release following deglaciation timing of initial rock avalanche runout deposition at one site is consistent with this conclusion though later instability episodes at the same site may have occurred independent of the influence of paraglacial stress release

geodynamics of the shanxi rift system china the pliocene quaternary shanxi rift system of northern china transsects the domal axis of the shanxi highlands and is defined by an s shaped string of asymmetric basins extending from huailai yanqing in the north via taiyuan to yuncheng in the south this rift system has a length of about 1200 km and a width of 20 80 km it is characterized by strong earthquakes its central nne trending transtensional segment forms the main element of the shanxi rift system basin subsidence commenced during the early pliocene along nne oriented master faults characterized by large strike slip rates 5 68 7 mm yr crustal extension amounts to some 1 4 km basins are separated by push up blocks destructive earthquakes m 7 8 are unevenly distributed the ene trending northern and southern branches of the shanxi rift system are characterized by orthogonal crustal extension along ene striking normal faults amounting to about 8 km these areas are characterized by a basin and range type structural style and weak seismic activity the shanxi rift system developed on a some 40 km thick thermally cool precambrian crustal segment that was overprinted during mesozoic diastrophic events there is only minor rift related volcanic activity the moho is pulled up by a few kilometers only under the axial rift zone sub moho compressional velocities are in the 8 0 8 1 km s range the shanxi rift system evolved in response to the build up of regional stress fields related to the collision of india and eurasia its localization involved reactivation of pre existing fracture systems

heterogeneous sources of the triassic granitoid plutons in the southern qinling orogen an e w tectonic division in central china 1 the qinling orogen is an important orogenic belt formed by the collision between the north and south china blocks along the mianlue suture during the triassic the orogen is customarily divided into the western and eastern qinling terranes however the boundary has long been a matter of debate there are many triassic granitoid plutons in the orogen especially in south qinling along the southern part of the shangdan suture systematic analysis of u pb ages and hf isotopes in zircons frxom six granitoid plutons including guangtoushan gaoqiaopu xiba laocheng dongjiangkou and zhashui from west to east allows us to trace their formation ages and source regions all plutons yield ages that vary only from 218 to 211 ma however zircon hf isotope data for these triassic plutons cluster in two distinct groups granitoids from the western segment i e guangtoushan gaoqiaopu and xiba of the south qinling belt have negative ehf t values 20 9 to 5 2 and relatively old two stage hf model ages 1 58 to 2 57 ga in contrast those from the eastern segment i e laocheng dongjiangkou and zhashui show higher ehf t values 5 4 to 6 8 and younger two stage hf model ages 0 82 to 1 60 ga integrating these analyses with published sr nd pb hf isotopic data we suggest that the division between the western and eastern south qinling segments is located near the taibai chenggu line between the baoji chengdu railway and 108 e longitude the integrated data suggest that the western south qinling segment separated from the north china block during the paleoproterozoic and early mesoproterozoic and then switched into continental convergence with the eastern south qinling segment northern margin of the yangtze block during the late mesoproterozoic to early neoproterozoic finally the two segments amalgamated during the late neoproterozoic

environmental evolution in the picos de europa cantabrian mountains sw europe since the last glaciation abstract the western massif of the picos de europa latitude 43 n longitude 4 5 w includes some of the highest peaks in the cantabrian mountains this massif was heavily glaciated during the last glaciation though the post glacial environmental evolution is still poorly understood using a complementary geomorphological and sedimentological approach we have reconstructed the environmental events occurred in this massif since the last pleistocene glaciation the geomorphological distribution of glacial landforms suggests the occurrence of four main glacial stages maximum glacial advance glacial expansion after the maximum advance late glacial and little ice age moreover a 5 4 m long sedimentary sequence was retrieved from the karstic depression of belbin providing a continuous record of the paleoenvironmental conditions in this area since the last glaciation until nowadays this section suggests that the maximum glacial expansion occurred at a minimum age of 37 2 ka cal bp significantly prior to the global last glacial maximum subsequently periglacial processes prevailed in the mid lands of the massif until glaciers expanded between 22 5 and 18 7 ka cal bp following the melting of the glaciers a shallow lake appeared in the belbin depression lake sediments do not show evidence of a cold stage during the late glacial when moraine systems formed at higher locations the terrestrification of this lake started at 8 ka cal bp and the area turned into grassland at 4 9 ka cal bp the existence of charcoal particles in the sediments of belbin sequence reveals the onset of human occupation in the massif through the use of fire activity for grazing purposes finally the presence of moraines inside the highest northern cirques shows evidence of the last glacial phase that occurred during the little ice age cold event since then the warming climate has led to the melting of these glaciers and periglacial processes prevail in the high lands of the massif

research history on glacial geomorphology and geochronology of the cantabrian mountains north iberia 43 42 n 7 2 w abstract the study of glacial geomorphology in the cantabrian mountains a mountain range that extends 460 km along the northern coast of the iberian peninsula sw europe started late in the 19th century and continues nowadays with a growing number of research papers however the number and timing of glaciations remains poorly understood partially due to the still limited number of numerical ages its southerly location and proximity to the atlantic ocean make this mountain range potentially sensitive to past climate fluctuations this work updates the glacial knowledge evolution for the whole range from the queixa invernadoiro massif to the basque mountains reviewing i the history of glacial research since the late 19th century ii the methodological approaches applied to reconstruct both the spatial extent and timing of past glacial stages and iii the main geomorphological and geochronological evidence reported until date including glacial features attributed to the last glacial cycle last 120 ka and previous glaciations according to current knowledge glaciers extended over the cantabrian mountains covering a total area of 3150 km2 showing asymmetric development conditioned by variations of the topographic configuration and moisture supply along the range available geochronology based on radiocarbon optically stimulated luminescence and terrestrial cosmogenic nuclides suggests the occurrence of at least 2 glacial advances during the last glacial cycle i a glacial maximum stage that took place at a minimum age of 36 45 ka marine isotope stage 3 and ii a second glacial advance at 19 23 ka mis 2 in some areas the extent of the glacier tongues during the second glacial advance was comparable to previous glacial maximum and was followed by glacial retreat conditions with formation of recessional moraines asynchronous glacial maximum conditions have been reported only for the castro valnera mis 4 3 numerical ages and queixa invernadoiro mis 6 1 numerical age massifs until now finally geomorphological evidence reported in picos de europa has been attributed to prior glaciations and correlated to cold conditions recorded during mis 12 and mis 22 based on a very limited number of numerical ages

paraglacial modification of slope form the morphological consequences of paraglacial modification of valley side drift slopes are investigated at six sites in norway here paraglacial slope adjustment operates primarily through the development of gully systems whereby glacigenic sediment is stripped from the upper drift slope and redeposited in debris cones downslope this results in an overall lowering of average gradient by up to 4 5 along gully axes in general slope profile adjustment appears to be characterized by a convergence of slope profiles towards an equilibrium form with an upper rectilinear slope gradient at 29 4 and a range of concavities of approximately 0 0 to 0 4 after initial rapid incision further gully deepening is limited but gullies become progressively wider as sidewall gradients decline to c 25 after which parallel retreat appears to predominate the final form of mature paraglacial gully systems consists of an upper bedrock floored source area a mid slope area of broad gullies whose sidewalls rest at stable moderate gradients and a lower slope zone where gullies discharge onto the surfaces of debris cones and fans some gullies appear to have attained this final form and have stabilized following exhaustion of readily entrainable sediment within decades of gully initiation at most sites paraglacial activity has transformed steep drift mantled valley sides into gullied slopes where an average of c 2 3 m of surface lowering has taken place at the most active sites these average amounts imply minimum erosion rates averaging c 90 mm a 1 since gully initiation which highlights the extreme rapidity of paraglacial erosion of deglaciated drift mantled slopes copyright 1999 john wiley sons ltd

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

paraglacial slope failures in the aran valley central pyrenees abstract slope failures are widespread phenomena in mid latitude mountain environments that were glaciated during the last glacial cycle this is the case of the aran valley in the upper garonne catchment central pyrenees that included glaciers several hundred meters thick following postglacial warming and ice thinning the recently deglaciated slopes were subject to intense stress readjustments the so called paraglacial dynamics we have identified up to 135 major slope failures in the aran valley with only 10 units occurring outside the glaciated domain of the maximum ice extent of the last glacial the presence of polished bedrock surfaces till and moraine ridges next to some of these features evidence a close connection between glacial and slope processes we have detected different types of slope failures affecting both bedrock 12 large catastrophic rock slope failures 16 rock slope deformation 34 rockfalls and 49 rockslides and unconsolidated glacial sediments 14 slope readjustments on drift mantled slopes the average altitude of rock slope failures oscillates between 1551 and 1991 m with a mean length ranging from 147 to 905 m and a width between 247 and 513 m the affected surface is also highly variable oscillating between 0 02 and 126 2 ha slope failures occur in different lithological settings but they are most frequent in slate lutite and limestone bedrocks we conclude that most of the failures show a paraglacial origin though other factors i e lithology and topography promoted slope instability

crustal structures across the western weihe graben north china implications for extrusion tectonics at the northeast margin of tibetan plateau the stable ordos plateau extensional weihe graben and qinling orogenic belt are located at the northeast margin of the tibetan plateau they have been thought to play different roles in the eastward expanding of the tibetan plateau peking university deployed a linear seismic array across the western end of the weihe graben to investigate the crustal structures of the tectonic provinces of this structure receiver function analyses revealed low to moderate poisson s ratios and anticorrelations between poisson s ratios and topography beneath the qinling orogen these features may indicate a tectonic thickening of the felsic upper crust by folding and thrusting within the qinling orogen we observed a strong horizontal negative signal at the midcrust beneath the ordos plateau which may indicate a low velocity zone this observation would suggest the stable cratonic ordos plateau had been modified due to the compression between the tibetan plateau and the ordos plateau we also observed an abrupt 4 km moho offset across the weihe fault changing from 44 km beneath the ordos plateau to 40 km beneath the qinling orogen we conclude that the weihe fault is a lithosphere scale fault shear zone which extends into the upper mantle beneath the weihe graben it acts as the major boundary separating the stable ordos plateau and the active qinling orogen

large ice contact slope movements glacial buttressing deformation and erosion glaciers and slope movements may act simultaneously to erode and modify glaciated slopes undercutting by glaciers can destabilize slopes but the extent to which slope failure may progress prior to subsequent glacier withdrawal has not hitherto been considered the traditional view has been that the buttressing effect of ice prevents slope movement the problem with this view is that ice is one third the density of rock and flows under low applied stress consequently failed slopes may move into the glacier if they exert a stress in excess of the resistance provided by the glacier slope movement rate depends on ice rheology and other factors influencing driving and resisting stresses simple viscous equations are used to investigate these variables the equations predict that small 108 m3 rockslides to test these estimates field evidence is presented of slope movements in glaciated valleys of new zealand narrowing or squeezing of glaciers adjacent to unstable rock slopes is demonstrated and considered to be the result of slope movement for one site geomorphic mapping and slope movement monitoring data show that movement rates are of similar order of magnitude to those predicted by the viscous equations closer agreement could be achieved with the application of modelling techniques that can more realistically model the complex slope geometries and stability factors encountered or by obtaining additional empirical data to calibrate the models this research implies that while the concept of glacial debuttressing the reduction of slope support from withdrawal of glaciers is valid complete debuttressing is not a prerequisite for the movement of ice contact rock slopes these slope movements may contribute to the erosional processes of glaciers and the evolution of glaciated slopes in a previously unrecognized way copyright 2012 john wiley sons ltd

pebbly versus bouldery rock glaciers morphology structure and processes abstract differences in rockwall geology cause two types of rock glaciers a bouldery rock glacier having the active layer composed of matrix free boulders derived from crystalline rocks and massive limestone and a pebbly rock glacier consisting of matrix supported debris derived from less resistant shale and platy limestone such material composition controls transport processes responsible for the shape size and internal structure of the two types of rock glaciers this paper compares the major processes controlling the morphology and structure of the two types in the swiss alps based on mapping description of geological and morphological characteristics direct observation of stratigraphy and geophysical soundings of internal structure in the swiss alps pebbly rock glaciers are distinguished from bouldery rock glaciers by the clast size of 15 20 cm in the mean b axis diameter the former are fed by small scale rockfalls debris flows and solifluction whereas the latter mainly originate from large rockfalls pebbly rock glaciers are generally smaller 100 k m in bouldery rock glaciers appears to originate from snow banks buried with deposits of large rockfalls from the large source rockwall

the last deglaciation in the picos de europa national park cantabrian mountains northern spain a sedimentological and geochemical study of the lago enol sequence cantabrian mountains northern spain together with detailed geomorphological mapping provides a first record of glacier evolution and climate change over the last 40 ka in the picos de europa national park the enol glacier retreated from its maximum extent prior to 40 ka bp as demonstrated by the onset of proglacial lacustrine sedimentation in two glaciated depressions the comella hollow to the north before 40 ka bp and the lago enol before 38 ka bp these results support previous evidence that the maximum extent of southern european glaciers occurred earlier than in northern europe alternation of homogeneous and laminated proglacial sediments during the glacier retreat illustrate a dynamic glacial evolution during the marine isotope stage mis 3 40 26 ka bp a slight warming is detected at 26 ka ago with the change from proglacial sediments in a lake located in contact to the glacier to glaciolacustrine sedimentation in a non contact or distal lake finally the onset of organic rich sediments took place at 18 ka ago this last transition occurred in two phases similarly to the north atlantic last termination suggesting a link between north atlantic deep water formation oscillations and palaeohydrological variability in the cantabrian mountains copyright 2009 john wiley sons ltd

spatial and temporal variability of periglaciation of the iberian peninsula abstract active periglacial processes are currently marginal in the iberian peninsula spatially limited to the highest mountain ranges however a wide variety of periglacial deposits and landforms are distributed in low and mid altitude environments which shows evidence of past periods of enhanced periglacial activity the purpose of this paper is to summarize the present knowledge of past periglacial activity in the iberian peninsula the chronological framework takes four main stages into account the last glaciation deglaciation holocene and present day processes this study focuses on the highest massifs pyrenees cantabrian range nw ranges central range iberian range sierra nevada as well as other lower elevation environments namely the central iberian meseta during the last glaciation the periglacial belt extended to much lower altitudes than today reaching current sea level in the nw corner of the iberian peninsula a wide range of geomorphological landforms and sedimentary records is indicative of very active periglacial processes during that phase in some cases related to permafrost conditions i e block streams rock glaciers most of the inactive landforms and deposits in low and mid elevations in iberia are also related to this phase the massive deglaciation of the iberian massifs was caused by a gradual increase in temperatures the deglaciation phase was only interrupted by a short period with colder conditions the younger dryas that reactivated periglacial processes in the formerly glaciated cirques of the highest lands specifically with the widespread development of rock glaciers during the holocene periglacial processes have been only active in the highest ranges shifting in altitude according to temperature regimes and moisture conditions the little ice age saw the reactivation of periglacial activity in lower elevations than today currently periglacial processes are only active in elevations exceeding 2500 m in the southern ranges and above 2000 2200 m in the northern massifs higher in sierra nevada in the south of iberian peninsula

crust and upper mantle structure of the north china craton and the ne tibetan plateau and its tectonic implications abstract understanding the mesozoic cenozoic tectonic evolution of the north china craton ncc and the ne tibetan plateau tp requires detailed knowledge of the lithospheric structure using dense regional networks and temporary deployments as well as updated reference models we obtain the crust and upper mantle structure to 120 km depth our tomographic results show several major features which have particular implications for the weihe shanxi rift system wsrs deformation of the ne tp and lithospheric evolution of the ncc beneath the wsrs the crust gradually thickens from south to north the lithospheric mantle gradually becomes slower and the mid lower crustal velocities are lower in the weihe rift where rifting of the wsrs initiated we suggest that along strike variations of the lithospheric structures of the wsrs have played an important role in its multistage evolution a low velocity zone lvz in the mid crust beneath the qilian orogen is characterized by relatively higher velocities compared to lvzs in other parts of the tp thus coherent lithospheric deformation may occur due to the high viscosity of the lvz during early plateau growth causing strong anisotropy to develop the western ncc including the ordos block and part of the alashan block shows a high velocity cratonic root extending to the base of our model in contrast the lithosphere of the eastern ncc appears to have been completely modified during the mesozoic through cenozoic and presents a thin lithosphere of relatively low velocities underlain by hot asthenosphere we observed significant upper mantle heterogeneities in the ncc which may reflect its diachronous lithospheric modification

quaternary glacial evolution in the central cantabrian mountains northern spain abstract the glacial evolution of the cantabrian mountains is not well known previous studies have focused on the extent of the glacial maximum and the presence of younger features in several massifs recently efforts have been made to date glacial periods particularly the glacial maximum this work presents a reconstruction of the glacial evolution in the cantabrian mountains providing data on the environmental characteristics and timing of the different stages from the quaternary glacial maximum to the little ice age the study area covers 3000 km 2 between the 4 58 w and 3 34 w and includes eleven massifs of the central area of the cantabrian mountains the selected sectors have an atlantic and atlantic mediterranean transitional climate and include the highest massifs above 2600 m and low altitude glacierised massifs lower than 2000 m glacial extent and evolution have been reconstructed on the basis of detailed geomorphological and morphostratigraphic mapping the equilibrium line altitude palaeo ela has been estimated for the different stages of each tongue the ela has been assessed by the aar and modified kurowski methods and altitude methods have been considered a numerical chronological framework is proposed using 17 ams radiocarbon and one osl data obtained in lake and bog deposits from three massifs four main glacial stages have been differentiated between 38 000 bp and the little ice age they correspond to different cold environments and the number of glacial stages varies from one to four among the different massifs conclusions are analysed in the context of the quaternary glacial evolution of other iberian mountains

topographic lithologic and glaciation style influences on paraglacial processes in the upper sil and luna catchments cantabrian mountains nw spain abstract deglaciated mountainous areas are usually affected by a great range of paraglacial processes that involve progressively denudation of glacial imprints this study focuses on paraglacial processes and glacial landform preservation in six zones located in two catchments of the cantabrian mountains nw spain these zones are adjacent but display important topographic lithologic and glaciation style differences an analysis of how these variables conditioned the intensity and diversity of paraglacial processes in these zones was investigated through a detailed study of their relief lithology and paleo glacier surface using gis a comprehensive cartography of paraglacial landforms was also accomplished considering landslides alluvial fans and rock glaciers that show signs of having been conditioned by glaciation moraines and debris mantled slopes were also included in the analysis to examine their grade of preservation depending on the studied variables data comparison show that differences in glaciation style influenced paraglacial processes in the ancient icefield area relief modification by glacial action was limited and scarce paraglacial processes occur by contrast in the upper areas located in the southern ranges where an alpine style of glaciation was installed paraglacial processes were very active generating many rock glaciers lithology explains some paraglacial landforms distribution 1 landslides are associated with incohesive sandy and shale rocks 2 rock glaciers mainly occur in quartzite areas 3 in limestone areas subterranean drainage contributes to glacial landscape preservation but suffosion dolines affect some glacial deposits topography is also a key factor in paraglacial processes 1 moraines are well preserved in gently sloping valleys but rare in the steeper where they are usually transformed into moraine or debris mantled slopes 2 alluvial fans are more frequent in the steeper valleys but more dissected by postglacial river action 3 elevation and orientation show little influence on paraglacial landforms except in the generation of some periglacial features such as rock glaciers

lateral variation of crustal structure in the ordos block and surrounding regions north china and its tectonic implications abstract crustal thicknesses and poisson s ratios in the ordos block and surrounding regions were estimated by the use of the h k stacking method on teleseismic receiver functions the data came from 353 temporary and permanent seismic stations in 2006 2011 results show that the crustal thickness and poisson s ratio gently vary within the ordos block with an average of 41 3 km and 0 265 respectively consistent with a felsic composition of the crust crustal thicknesses predicted on the basis of airy isostasy are consistent with the estimated thicknesses implying that the topography is approximately compensated the reactivated portion of the north china craton that has undergone mesozoic cenzoic lithospheric thinning is also characterized by the thinning crust while the ordos block maintains normal crustal thickness and average crustal velocity inferred higher densities in the lower crust and the anti correlation between poisson s ratio and crustal thickness in the ordos block may be the result from underplating of mafic magmas in the precambrian around the ordos block the paleoproterozoic khondalite zone in the northern edge has higher poisson s ratio and thickened crust which is consistent with the lower crust being of more mafic composition the weihe shanxi graben in the southeastern edge has mid high poisson s ratio high heat flow and thinning crust which is consistent with the known transtensional tectonic setting in the liupanshan thrust belt along the southwestern edge of the ordos plateau significant variations in crustal thicknesses and poisson s ratios occur on two sides besides a thickened crust a concaved moho implies horizontal shortening of this edge of the ordos block due to its collision with the northeastern tibetan plateau the structural differences between the eastern and western edges of the ordos block reflect that the ordos block is in tectonic stress environment of the western compression and the eastern extension

structural records of the late cretaceous cenozoic extension in eastern china and the kinematics of the southern tan lu and qinling fault zone anhui and shaanxi provinces pr china abstract our study of the late cretaceous cenozoic extension in eastern china is a kinematic analysis of faults 1500 striated fault data 175 stress solutions at 90 sites that has permitted us to separate stress fields belonging to six tectonic events a wnw ese extension 1 has affected eastern china from the campanian to the late palaeocene early ypresian under this extension the qinling qlfz and southern tan lu stlfz fault zones have been dextral transtensional fault zones a first transpressional event 2 nne ssw shortening has occurred during the late ypresian lower lutetian the qlfz and the stlfz have been dextral transpressional fault zones a ne sw extension 3 has affected the weihe graben during the palaeogene after a second transpressional event 4 the ne sw extension 5 has been rejuvenated during the late miocene and the qlfz has been a normal fault zone again and the stlfz a sinistral transtensional fault zone synrift subsidence has occurred in the weihe graben the second transpressional event 4 wnw ese shortening has occurred during the late oligocene early miocene during a period of uplifting and exhumation at that time the stlfz and the qlfz have become sinistral transpressional fault zones a period of extension 6 has taken place during the late pliocene quaternary the extensional direction has trended nnw sse during this event the qlfz has been a sinistral transtensional fault zone and the stlfz a dextral transtensional fault zone these results are compared with those previously published in order to evaluate the regional significance of these tectonic events

glaciers and rivers pleistocene uncoupling in a mediterranean mountain karst abstract large scale coupling between headwater catchments and downstream depocentres is a critical influence on long term fluvial system behaviour and on the creation of the fluvial sedimentary record however it is often difficult to examine this control over multiple quaternary glacial cycles and it has not been fully explored in karst basins by investigating the pleistocene glacial and fluvial records on and around mount orjen 1894 m in montenegro we show how the changing connectivity between glaciated mountain headwater source zones and downstream alluvial basins is a key feature of long term karst system behaviour especially in relation to the creation and preservation of the surface sedimentary record middle and late pleistocene glacial deposits are well preserved on mount orjen uranium series dating of 27 carbonate cements in fluvial sediments shows that many alluvial depocentres were completely filled with coarse glacial outwash before 350 ka during the largest recorded glaciation this major glaciation is correlated with the skamnellian stage in greece and marine isotope stage 12 mis 12 c 480 420 ka this was a period of profound landscape change in many glaciated catchments on the balkan peninsula later glaciations were much less extensive and sediment supply to fluvial systems was much diminished the extreme base level falls of the late miocene produced the world s deepest karst networks around the mediterranean after mis 12 the subterranean karst of mount orjen formed the dominant pathway for meltwater and sediment transfer so that the depositional basins below 1000 m became disconnected uncoupled from the glaciated headwaters there is little evidence of post mis 12 aggradation or incision in these basins this absence of later pleistocene and holocene fluvial activity means these basins contain some of the thickest and best preserved outwash deposits in the mediterranean

large rock slope failures in the highlands of scotland characterisation causes and spatial distribution abstract a comprehensive database of larger rock slope failures rsfs has been compiled and characterised for a whole mountain range possibly for the first time apart from iceland most rsfs in the scottish highlands occurred soon after deglaciation a threshold size of 0 25 km 2 focuses on rsfs which contribute significantly to gross erosion in the glacial paraglacial cycle and on the spatial concentration of this poorly recognised process database verification indicates that at least 90 of the total extant population in the highlands is covered standard mass movement typologies are broadly applicable but require some refinement to characterise rsfs in a passive margin glaciated mountain range comprised mainly of ancient metasediments most larger rsfs here are complex and difficult to categorise a continuum from cataclasmic failures including rock avalanches through arrested translational slides to almost in situ slope deformations is identified the prevailing modes of large rsf are arrested short travel translational sliding and gravitational sagging cataclasmic failure is rare and sub cataclasmic outcomes are more evident a significant class of deformations exhibits compressional rather than extensional features and may be responding to localised glacio isostatic rebound stresses the large rsf population is widely but very unevenly distributed across the main mountain areas 65 are in seven main clusters with the rest non randomly scattered previous glaciological lithological and seismotectonic explanations are insufficient to explain this spatial pattern and overlook the basic engineering geology prerequisites for failure massifs of similar relief and lithology can display intense or sparse rsf incidence geomorphological appraisal suggests an association with recently active glacial breaches of main and secondary watersheds with rsf being scarce or absent in valleys inherited from tertiary uplift and in mountain groups away from the main watersheds valleys which adapted early to ice discharge are seen as stress hardened with their slopes unlikely to reach critical thresholds for failure after subsequent reoccupations by ice concentrated erosion in the last glaciations is most likely to be found close to where breaches are actively forming or enlarging such erosion in the slope foot and valley floor may have daylighted failure planes or generated rebound stresses augmenting those from other endemic sources sufficiently to provoke widespread paraglacial rsf slope stress models for deglaciated valleys and comparative studies in other glaciated mountain ranges are required to test this concept and may assist in geohazard assessments

paraglacial slope adjustment since the end of the last glacial maximum and its long lasting effects on secondary mass wasting processes hauser kaibling austria abstract this study indicates the possible long lasting impacts of deep seated gravitational slope deformation dgsd on erosional and mass movement processes dgsd features are common large scale landforms in the crystalline basement rocks of the central alps of austria inactive forms are related to paraglacial nonglacial processes directly conditioned by former glaciation and deglaciation rock slope adjustment processes acting after glacier retreat towards the end of the late glacial period the near surface metamorphic bedrock of dgsd features is generally disintegrated such rock type favours erosion and the formation of small landslides field data laboratory analyses aerial photographs and gis based terrain analyses are used to describe the different geomorphic effects of an extremely disintegrated rock slope the studied dgsd hauser kaibling 13 6 km2 is located in central austria during the last glacial maximum the adjacent valley glacier reached an altitude of approximately 1900 m a s l glacier retreat in combination with the unfavourable tectono metamorphic setting caused gravity induced stresses to act subsequent sediment build up in the main valley restabilised the slope linear erosion cut a number of gullies into the lower part of the dgsd calculated mean erosional denudation rates at incised valley sections range from 0 5 to 2 6 mm a 1 since deglaciation smaller active landslides on the sides of the steep gullies draining the dgsd contribute to high denudation rates active landsliding is favoured by i fragmented rock ii steep slopes iii supply of surface and subsurface water by rain and snowmelt and iv human impact debris flows and debris charged flood events occurred frequently in the past during such events material was transported from the unstable slopes to the populated alluvial fans thus knowledge about the spatial distribution and the stage of development of dgsds active and currently inactive provides an important basis for risk management measures