intersections between wind regimes topography and sediment supply perspectives from aeolian landforms in central asia abstract the widespread aeolian deposits of the central asian steppes and piedmonts offer potential to better understand the dynamics of the major eurasian climate subsystems over quaternary timescales however current assumptions linking climate processes with aeolian activity remain poorly substantiated and potentially problematic emerging datasets suggest that loess accumulation rates and the timing of peak dust flux along the tien shan piedmont are highly variable between sites the degree to which desert dunes reflect wind regimes and therefore provide records of climate circulation is unknown and the presumed genetic link between the region s desert dunes and piedmont loess deposits remains hypothetical these uncertainties raise questions as to the nature of the relationship between aeolian flux deposition and palaeo climate here we investigate the relationship between wind regimes and the distribution morphology and timing of two aeolian landform types dunes and loess in the topographically diverse ili basin of southeast kazakhstan and western china we establish late holocene ages for three dune sites and one loess profile and infer that the location and morphology of these landforms can be used to test their genetic link with recent wind regimes we assess the morphologic characteristics of linear dunes at four sites using a semi automated mapping approach and analyse the variability in dune orientations with respect to sand shifting wind trajectories identified from meteorological reanalysis data for each site the most frequently occurring wind direction appears to be responsible for sediment supply while the strongest winds drive dune orientation wind orientations are strongly influenced by topography back trajectories incorporating dust transport and deposition potential to the loess site suggest both westerly and northerly delivery of fine grained material to the piedmont and that the most common source areas lie in regions where surface sediment contains a mixture of coarse and fine grained material to facilitate entrainment into suspension

kinematic models of fluvial terraces over active detachment folds constraints on the growth mechanism of the kashi atushi fold system chinese tian shan during detachment folding the relationship between differential uplift and shortening depends on the mechanism of fold growth such as limb rotation or hinge migration and may vary over the lifetime of a fold thus neither long term shortening rates nor the present fold geometry unambiguously constrain the kinematics of fold growth where rivers cut through growing anticlines flights of abandoned fluvial terraces act as passive kinematic markers as shortening progresses the terraces become deformed and thereby preserve critical information about the kinematics and evolution of active fold growth to constrain recent fold growth across three detachment folds in the kashi atushi fold system in the sw tian shan china we surveyed flights of deformed terraces and compared them with geometric models of successively emplaced horizontal unconformities terraces across pregrowth strata deformed by hinge migration limb rotation and a combination of the two migration of angular hinges and curved hinge zones were also compared each kinematic model predicts both a distinct geometry for the deformed terraces and contrasting angular relationships between the terraces and the pregrowth strata notably limb rotation and migration of curved hinge zones result in progressively rotated terraces that cut across pregrowth strata whereas all limb lengthening models result in parallelism between pregrowth strata and terrace straths across much of the fold the kashi atushi terraces show clear evidence of abandoned axial surfaces concentrated deformation near the core of the folds and progressive tilting with age when compared to the model predictions the folds are likely growing by a combination of limb rotation in the tight cores of the folds and hinge zone migration of pregrowth strata across the flanks of the folds

grain size dependent concentration of cosmogenic 10be and erosion dynamics in a landslide dominated himalayan watershed for documenting recent or late quaternary erosion rates at the scale of a small watershed or even an entire mountain range the use of in situ terrestrial cosmogenic nuclides tcn such as 10be in river sediments has become widespread over the last decade in mountainous settings however landslides may induce a two fold complication in the cosmogenic nuclide budget first they may episodically deliver large amounts of sediment with low tcn concentrations to the river channel second they may generate a grain size concentration dependence in these sediments however studies that have explored grain size dependence in landslide dominated areas have reached differing conclusions and the underlying mechanisms remain poorly understood the present study focuses on the khudi khola river basin a small drainage basin in the central himalayas the area is characterized by steep slopes heavy rainfall and high sediment production rates importantly the watershed contains a large area of active landsliding in situ 10be was analyzed in sediments of grain sizes ranging from 75 m to 4 cm collected from five locations upstream downstream and in the small tributaries which drain the landslides in all sampling locations including those situated upstream of the landslides the finest grains 75 250 m are two to four times more concentrated in 10be than the largest clasts 4 7 mm we developed a numerical slope model which includes a low level of background soil erosion and episodic denudation from large mass wasting events we then introduced a coarsening of average grain size with soil depth to the model our simulation shows that the data available for this valley are compatible with a scenario in which landslides deliver coarse grains to the channel that are less concentrated in tcn and have deeper provenance best fit estimates of the model parameters suggest recurrence times of 3000 to 9000 years for a major landslide on the same slope and mean long term landslide denudation rates of 1 7 to 4 7 mm yr 1 a negative correlation between tcn concentration and grain size is also observed directly upstream and 5 km downstream of the landsliding area suggesting that nearly all of the sediment carried by the river is derived from ancient landslides while almost no sediment is supplied by erosion of soil mantled slopes despite these complications apparent denudation rates directly derived from the tcn concentrations and from previously published data in the region are all on the same order of magnitude around 2 mm yr 1 however a factor of three variability remains between the different studies depending on the location the year of sampling and the analyzed grain size fraction thus although tcn derived average denudation rates provide a useful first order estimate even in fast eroding terrains dominated by landslides caution should be applied when using quantitative results in such settings

intracontinental subduction and palaeozoic inheritance of the lithosphere suggested by a teleseismic experiment across the chinese tien shan teleseismic tomography across the chinese tien shan shows that seismic wave speeds in the lithosphere beneath central tien shan are high and therefore the lithosphere is not weaker than that beneath the adjacent undeformed tarim and junggar basins there is evidence for significant velocity contrasts within the lithosphere that are presumably inherited from the palaeozoic collision history the high velocity thick yili block observed underneath the northern tien shan is a clue for shortening by a intracontinental subduction the observed geometry is consistent with a simple model of intracontinental subduction and suggests that during orogeny the lithosphere has remained heterogeneous and has deformed along existing planes of weakness rather than by homogeneous thickening of a particularly weak lithosphere

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

active thrusting and folding along the northern tien shan and late cenozoic rotation of the tarim relative to dzungaria and kazakhstan we have studied geometries and rates of late cenozoic thrust faulting and folding along the northern piedmont of the tien shan mountain belt west of urumqi where the m 8 3 manas earthquake occurred on december 23 1906 the northern range of the tien shan rising above 5000 m overthrusts a flexural foredeep filled with up to 11 000 m of sediment of the dzungarian basement our fieldwork reveals that the active thrust reaches the surface 30 km north of the range front within a 200 km long zone of neogene quaternary anticlines fault scarps are clearest across inset terraces within narrow valleys incised through the anticlines by large rivers flowing down from the range in all the valleys the scarps offset vertically the highest terrace surface by the same amount 10 2 0 7 m inferring an early holocene age 10 2 kyr for this terrace which is continuous with the largest recent fans of the piedmont yields a rate of vertical throw of 1 0 0 3mm yr on the main active thrust at the surface a quantitative morphological analysis of the degradation of terrace edges that are offset by the thrust corroborates such a rate and yields a mass diffusivity of 5 5 2 5 m 2 kyr a rather fresh surface scarp 0 8 0 15 m high that is unlikely to result from shallow earthquakes with 6 m 7 in the last 230 years is visible at the extremities of the main fold zone we associate this scarp with the 1906 manas earthquake and infer that a structure comprising a deep basement ramp under the range gently dipping flats in the foreland and shallow ramps responsible for the formation of the active fault propagation anticlines could have been activated by that earthquake if so the return period of a 1906 type event would be 850 380 years the small size of the scarp for an earthquake of this magnitude suggests that a large fraction of the slip at depth 2 3 is taken up by incremental folding near the surface comparable earthquakes might activate flat detachments and ramp anticlines at a distance from the front of other rising quaternary ranges such as the san gabriel mountains in california or the mont blanc aar massifs in the alps we estimate the finite cenozoic shortening of the folded dzungarian sediments to be of the order of 30 km and the cenozoic shortening rate to have been 3 1 5 mm yr assuming comparable shortening along the tarim piedmont and minor additional active thrusting within the mountain belt we infer the rate of shortening across the tien shan to be at least 6 3 mm yr at the longitude of manas 85 5 e a total shortening of 125 30 km is estimated from crustal thickening assuming local airy isostatic equilibrium under the same assumption serial n s sections imply that cenozoic shortening across the belt increases westwards to 203 50 km at the longitude of kashgar 76 e as reflected by the westward increase of the width of the belt this strain gradient implies a clockwise rotation of tarim relative to dzungaria and kazakhstan of 7 2 5 around a pole located near the eastern extremity of the tien shan west of hami 96 e 43 5 n comparable to that revealed by paleomagnetism between tarim and dzungaria 8 6 8 7 a 6 mm yr rate of shortening at the longitude of manas would imply a rate of rotation of 0 45 m y and would be consistent with a shortening rate of 12 mm yr north of kashgar taking such values to be representative of late cenozoic rates would place the onset of reactivation of the tien shan by the india asia collision in the early to middle miocene 16 22 9 m y in accord with the existence of particularly thick late neogene and quaternary deposits such reactivation would thus have started much later than the collision roughly at the time of the great mid miocene changes in tectonic regimes denudation and sedimentation rates observed in southeast asia the himalayas and the bay of bengal and of the correlative rapid change in seawater sr isotopic ratio 20 to 15 ma like these other changes the rise of the tien shan might be a distant consequence of the end of indochina s escape

evaluating fluvial terrace riser degradation using lidar derived topography an example from the northern tian shan china abstract the morphological degradation of fluvial terrace risers provides a constraint to terrace chronology in this study we morphologically date the terrace risers along the kuitun river on the north flank of the tian shan china and subsequently discuss possible relationships between terrace formation and the past regional climate changes and tectonic activity of the dushanzi fault related fold to do this 159 topographic profile swaths of terrace risers were extracted from lidar derived dem and were analysed to determine a range of best fitting morphological ages through monte carlo simulation a locally applicable sediment transport coefficient diffusivity was calibrated as 5 5 1 6 m 2 ky given the morphological age of the t1 t2 riser and its independently known age taking this calibrated coefficient we estimate age ranges of 11 6 3 4 ka 6 5 1 4 ka 5 3 1 1 ka and 4 2 1 2 ka for terraces t3 t4 t5 and t6 respectively under the assumption that the age of the riser is close to the abandonment age of the lower surface these new terrace ages combining climate proxy records from the oxygen isotope curve from the guliya ice cap and paleoearthquake events in the dushanzi fault related fold suggest that tectonic activity may be an important factor in the formation of lower terraces within the growing anticlines while in more extensive areas beyond anticlines climate changes controlled the main deposition and incision events in the present study area and thus terrace formation of t1 t3

separation of ash and sulfur dioxide during the 2011 grimsvotn eruption modeling the transport of volcanic ash and gases released during volcanic eruptions is crucially dependent on knowledge of the source term of the eruption that is the source strength as a function of altitude and time for the first time an inversion method is used to estimate the source terms of both volcanic sulfur dioxide so2 and ash it was applied to the explosive volcanic eruption of grimsvotn iceland in may 2011 the method uses input from the particle dispersion model flexpart flexible particle dispersion model a priori source estimates and satellite observations of so2 or ash total columns from infrared atmospheric sounding interferometer to separately obtain the source terms for volcanic so2 and fine ash the estimated source terms show that so2 was emitted mostly to high altitudes 5 to 13 km during about 18 h 22 may 00 18 utc while fine ash was emitted mostly to low altitudes below 4 km during roughly 24 h 22 may 06 utc to 23 may 06 utc flexpart simulations using the estimated source terms show a clear separation of so2 transported mostly northwestward and the fine ash transported mostly southeastward this corresponds well with independent satellite observations and measured aerosol mass concentrations and lidar measurements at surface stations in scandinavia aircraft measurements above iceland and germany confirmed that the ash was located in the lower atmosphere this demonstrates that the inversion method in this case is able to distinguish between emission heights of so2 and ash and can capture resulting differences in transport patterns key points ash and so2 source terms estimated using inverse techniques and satellite data the transport and separation of ash and so2 are modeled model simulations correspond well with a range of independent observations 2014 the authors

flow to a heated borehole in porous thermoelastic rock analysis exact solutions are obtained for fluid flow induced by the heating of a borehole the rock is modeled as a fluid saturated porous thermoelastic medium the temperature and pore pressure fields are governed by a pair of diffusion equations which are coupled through a source term in the pressure equation proportional to the temperature rate the pressure profile exhibits a maximum that grows in magnitude and propagates away from the borehole for a constant heat flux applied as an instantaneous step the fluid flux to the borehole takes a finite initial value and decays monotonically when the heat flux exhibits a finite rise time the fluid flux is initially zero rises to a maximum and then decays at late time the inverse of the fluid flux is linear in ln t this observation can be exploited to estimate the permeability and fluid diffusivity of low permeability rock sample calculations are shown for westerly granite

analysis of scarp profiles evaluation of errors in morphologic dating morphologic analysis of scarp degradation can be used quantitatively to determine relative ages of different scarps formed in cohesionless materials under the same climatic conditions scarps of tectonic origin as well as wavecut or rivercut terraces can be treated as topographic impulses that are attenuated by surface erosional processes this morphological evolution can be modelled as the convolution of the initial shape with erosion or degradation function whose width increases with time such modeling applies well to scarps less than 10m high formed in unconsolidated fanglomerates to a good approximation the degradation function is gaussian with a variance measuring the degree of rounding of the initial shape this geometric parameter can be called the degradation coefficient a synthetic experiment shows that the degradation coefficient can be obtained by least squares fitting of profiles levelled perpendicular to the scarp gravitational collapse of the free face is accounted for by assuming initial scarp slopes at the angle of repose of the cohesionless materials 30 35 uncertainties in the measured profiles result in an uncertainty in degradation coefficient that can be evaluated graphically because the degradation coefficient is sensitive to the regional slope and to three dimensional processes gullying loess accumulation stream incision etc a reliable and accurate determination of degradation coefficient requires several long profiles across the same scarp the linear diffusion model of scarp degradation is a gaussian model in which the degradation coefficient is proportional to numerical age in that case absolute dating requires only determination of the propotionality constant called the mass diffusivity constant for holocene scarps a few meters high in loose alluvium under arid climatic conditions mass diffusivity constants generally range between 1 and 6 m 2 kyr morphologic analysis is a reliable method to compare ages of different scarps in a given area and it can provide approximate absolute ages of holocene scarplike landforms

late quaternary slip rates across the central tien shan kyrgyzstan central asia 1 slip rates across active faults and folds show that late quaternary faulting is distributed across the central tien shan not concentrated at its margins nearly every intermontane basin contains neogene and quaternary syntectonic strata deformed by holocene north south shortening on thrust or reverse faults in a region that spans two thirds of the north south width of the central tien shan slip rates on eight faults in five basins range from 0 1 to 3 mm yr fault slip rates are derived from faulted and folded river terraces and from trenches radiocarbon optically stimulated luminescence and thermoluminescence ages limit ages of terraces and aid in their regional correlation monte carlo simulations that sample from normally distributed and discrete probability distributions for each variable in the slip rate calculations generate most likely slip rate values and 95 confidence limits faults in basins appear to merge at relatively shallow depths with crustal scale ramps that underlie mountain ranges composed of pre cenozoic rocks the sum and overall pattern of late quaternary rates of shortening are similar to current rates of north south shortening measured using global positioning system geodesy this similarity suggests that deformation is concentrated along major fault zones near range basin margins such faults separated by rigid blocks accommodate most of the shortening in the upper crust index terms 8107 tectonophysics continental neotectonics 9320 information related to geographic region asia 8010 structural geology fractures and faults

active thrust sheet deformation over multiple rupture cycles a quantitative basis for relating terrace folds to fault slip rates many recent thrust fault earthquakes have involved coseismic surface faulting and folding revealing the multifaceted nature of active thrust sheet deformation we integrate records of surface deformation subsurface structure and geochronology to investigate active surface deformation over multiple rupture cycles across the southern junggar thrust sjt in the southern junggar basin nw china fluvial terrace geometries extracted from a 1 m digital elevation model reveal records of surface faulting across a prominent fault scarp in addition terraces exhibit progressive folding across fold scarps fault and fold scarps are spatially coincident with a surface emergent sjt splay and subsurface fault bends along the sjt respectively constrained by seismic reflection data we quantify the magnitude of fault slip at depth implied by fold scarps along holocene aged terraces our method yields results consistent with independent estimates of slip implied by fault scarp relief for the same terraces four late quaternary terrace records are less continuous preserved only as fold scarps that suggest folding kinematics involving a component of limb rotation we develop a new method for quantifying fault slip at depth from terrace folds using a mechanical forward modeling approach our analysis yields quantitative relations between fold dip and fault slip allowing us to quantify sjt fault slip from terrace folds from 250 ka present sjt fault slip rate has decelerated from 7 0 mm yr in the late quaternary to 1 3 mm yr throughout the holocene these results provide new insight into the kinematics of fault bend folding for natural structures and define new methods to accurately estimate fault slip and slip rates from terrace folds in active thrust sheets

injection of gases into the stratosphere by explosive volcanic eruptions 1 explosive eruptions can inject large amounts of volcanic gases into the stratosphere these gases may be scavenged by hydrometeors within the eruption column and high uncertainties remain regarding the proportion of volcanic gases which eventually reach the stratosphere these are caused by the difficulties of directly sampling explosive volcanic eruption columns and by the lack of laboratory studies in the extreme parameter regime characterizing them using the nonhydrostatic nonsteady state plume model active tracer high resolution atmospheric model atham we simulated an explosive volcanic eruption we examined the scavenging efficiency for the climatically relevant gases within the eruption column the low concentration of water in the plume results in the formation of relatively dry aggregates more than 99 of these are frozen because of their fast ascent to low temperature regions consideration of the salinity effect increases the amount of liquid water by one order of magnitude but the ice phase is still highly dominant consequently the scavenging efficiency for hcl is very low and only 1 is dissolved in liquid water however scavenging by ice particles via direct gas incorporation during diffusional growth is a significant process the salinity effect increases the total scavenging efficiency for hcl from about 50 to about 90 the sulfur containing gases so2 and h2s are only slightly soluble in liquid water however these gases are incorporated into ice particles with an efficiency of 10 to 30 despite scavenging more than 25 of the hcl and 80 of the sulfur gases reach the stratosphere because most of the particles containing these species are lifted there sedimentation of the particles would remove the volcanic gases from the stratosphere hence the final quantity of volcanic gases injected in a particular eruption depends on the fate of the particles containing them which is in turn dependent on the volcanic and environmental conditions

borehole stability analysis in a thermoporoelastic dual porosity medium the problem of diffusion and mass transfer in dual porous media is considered in a threephase framework the solid phase is assumed to contain two distinct cavities filled with fluid the porous mixture is composed of two overlapping media the porous blocks and the fissure network the fluid can transfer between the cavities due to fluid pressure difference in addition hydraulic and thermal diffusions take place through the mixture a global understanding of mass transfer diffusion and deformation is provided the governing equations associated with these phenomena are presented for a mixture in thermal equilibrium the finite element approximation of the governing equations is formulated and applied to the stability analysis of a vertical borehole a parametric analysis is carried out to evaluate the influence of mass transfer on the pressure profiles of the fluids around the borehole permeable and a semipermeable boundary conditions are compared to predict the potential for failure of the wellbore under drained and partially undrained conditions

a new shortening rate across the dushanzi anticline in the northern tian shan mountains china from lidar data and a seismic reflection profile abstract in the northern foreland basin of the tian shan mountains strata have been intensively deformed as a result of the ongoing cenozoic indian eurasian collision the dushanzi anticline lies in the northernmost deformation belt of the tian shan mountains understanding the shortening rate and paleoseismicity of the dushanzi anticline is important for both understanding the propagation of the thrust front of the tian shan mountains and for assessing seismic hazards in this highly populated area here we integrate lidar derived topographic data a high quality seismic reflection profile and field observations across the dushanzi anticline to resolve the holocene deformation history of the anticline a reconstructed longitudinal profile along the kuitun river that flows across the dushanzi anticline demonstrates a holocene history of both folding and faulting the total shortening from faulting is 4 4 0 1 m while the shortening accommodated by folding is 12 6 1 1 m since 7 5 10 ka b p a total of 17 0 1 1 m of shortening has occurred across the dushanzi anticline in the holocene at a rate of 2 0 0 2 mm a this shortening represents up to 18 of the 11 mm a total shortening rate across the entire eastern tian shan mountains at this longitude the holocene shortening rate of the dushanzi anticline is 6 times greater than its long term average shortening rate 0 3 0 1 mm a since 4 8 ma furthermore we analyzed a displaced terrace sequence at a site along the dushanzi frontal fault and found that the average coseismic dip slip displacement is 2 5 0 1 m with an average recurrence interval of 2 8 0 3 ka

crustal and upper mantle structure under the tien shan from surface wave dispersion long period seismograms of nuclear explosions and natural earthquakes in central asia recorded at three digital stations of the laboratoire de detection geophysique ldg network in france attest to a significant propagation effect in the tien shan area this allows for an investigation of the deep structures under the range which has been the site of particularly intense intracontinental deformation since about the middle miocene group velocity curves have been obtained by regionalization for pure paths across either the central or eastern tien shan they indicate a crust of approximately 50 55 km in thickness and particularly low shear wave velocities under the central tien shan our study suggests lateral variation of the deep structures under the range which could be related to a westward increase along the range of cumulative amount and rate of shortening

insights into the dynamics of mafic magmatic hydromagmatic eruptions from volatile degassing behaviour the hverfjall fires iceland abstract the style and intensity of hydromagmatic activity is governed by a complex interplay between the relative volumes of magma and water that interact their relative viscosities the depth of subsurface explosions the substrate properties and the vent geometry fundamental questions remain however regarding the role of magmatic vesiculation in determining the dynamics of magma water interaction mwi petrological reconstructions of magmatic degassing histories are commonly employed to interpret the pre and syn eruptive conditions during dry magmatic eruptions but the application of similar techniques to hydromagmatic activity has not yet been fully explored in this study we integrate glass volatile measurements s cl h2o and co2 with field observations and microtextural measurements to examine the relationship between degassing and eruptive style during the hverfjall fires fissure eruption iceland here coeval fissure vents produced both dry magmatic jar ba sholar scoria cone complex and variably wet hydromagmatic hverfjall tuff ring activity generating physically distinct pyroclastic deposits with contrasting volatile signatures matrix glass volatile concentrations in hydromagmatic ash 883 172 1 ppm s 0 45 0 03 1 wt h2o 20 ppm co2 are consistently elevated relative to magmatic ash and scoria lapilli 418 93 1 ppm s 0 12 0 48 1 wt h2o co2 below detection and overlap with the range for co erupted phenocryst hosted melt inclusions 1522 127 1 ppm s 165 27 1 ppm cl measurements of hydromagmatic glasses indicate that the magma has degassed between 17 and 70 of its initial sulfur prior to premature quenching at variably elevated confining pressures by comparing volatile saturation pressures for both magmatic and hydromagmatic glasses and how these vary through the eruptive stratigraphy we place constraints on the conditions of mwi crucially our data demonstrate that the magma was already vesiculating when it encountered groundwater at depths of 100 200 m and that the external water supply was sufficient to maintain mwi throughout the eruption with no significant vertical or lateral migration of the fragmentation surface we propose that development of an in vent water sediment slurry provides a mechanism through which the elevated confining pressures of 1 6 2 6 mpa or up to 6 mpa accounting for uncertainty in co2 below analytical detection could be maintained and buffered throughout the eruption whilst enabling vertical mixing and ejection of fragmented juvenile and lithic material from a range of depths importantly these results demonstrate that the volatile contents of hydromagmatic deposits provide valuable records of 1 the environment of mwi e g groundwater versus surface water vertical migration of the fragmentation level and 2 the state of the magma at the time of fragmentation and quenching we further suggest that the volatile content of tephra glasses provides a reliable alternative or additional indicator of a hydromagmatic origin particularly for reduced ocean island basalts where late stage volatile saturation and degassing s h2o occurs over a pressure range relevant to typical mwi environments

late oligocene miocene intra continental mountain building of the harke mountains southern chinese tian shan evidence from detrital aft and ahe analysis abstract as the largest intra continental mountain belt in central asia the tian shan mountain range underwent a diachronous uplift history in different regions the present crustal shortening rate of this mountain range is also characterized by an along strike variation and decreases from west to east the harke mountains located in the middle part of the southern tian shan accommodate a relatively lower crustal shortening rate but host the highest topography of this mountain range this study aims to restore the cenozoic mountain building history of the harke mountains detrital aft and ahe analyses were conducted for paleocene pliocene sediments and modern moraines in the kuqa depression an abrupt increase in the lag time of the detrital aft young age components at 26 23 ma indicates that the uplift of the southern tian shan initiated in the late oligocene early miocene which is consistent with the regional tectonic activation of the tian shan mountain range in the late miocene the basement of the harke mountains underwent rapid exhumation from 10 to 6 ma comparing our result with previously published tectonic data we infer that the intense exhumation in our study area corresponds to the intensified deformation of the whole tian shan mountain range in the late miocene which was probably driven by the accelerated convergence between the tarim and tian shan

morphologic dating of scarps formed by repeated slip events along the san andreas fault carrizo plain california morphologic dating of fault scarps determines late cenozoic fault activity by comparing observed topographic profiles with those determined using a calibrated hillslope development model we postulate that the material transport rate along the profile is a function only of local slope and is transport limited morphologic dating of hillslopes bounded by continuously dropping boundaries or cut by continuously slipping faults is used to determine the material transport rate constant the time since the downdrop was initiated or the fault began to slip we calibrated the hillslope development model on the southwest facing scarp southeast of wallace creek along the san andreas fault saf in the carrizo plain california the scarp has been exposed by right lateral offset of a southeast sloping shutter ridge located on the southwest side of the saf and by vertical offset related to secondary deformation we assume that all the observed offset occurs after initial exposure of the scarp by passage of the shutter ridge forward modeling of profile development yielded a mass diffusivity of 8 6 0 8 m2 kyr 1 normal fault slip rates were determined for two graben bounding faults in the northern elkhorn hills in the southeastern carrizo plain by applying the calibrated to the degradation of the scarps to determine the scarp age one fault scarp began to form about 12 kyr ago and the other about 63 kyr ago those ages and estimates of the dip slip along the faults result in slip rates of 1 2 mm yr 1

application of in situ produced cosmogenic 10be and 26al to the study of lateritic soil development in tropical forest theory and examples from cameroon and gabon abstract depth profiles of in situ produced cosmogenic nuclides including 10 be t 1 2 1 5 10 6 years and 26 al t 1 2 0 73 10 6 years in the upper few meters of the earth s crust may be used to study surficial processes quantifying denudation and burial rates and elucidating mechanisms involved in landform evolution and soil formations in this paper we discuss the fundamentals of the method and apply it to two lateritic sequences located in african tropical forests

late pleistocene acceleration of deformation across the northern tianshan piedmont china evidenced from the morpho tectonic evolution of the dushanzi anticline we document the temporal evolution of deformation in the northern tianshan piedmont where the deformation is partitioned across several thrusts and folds we focus on the dushanzi anticline where abandoned terraces and growth strata allow us to constrain the history of folding since the miocene based on subsurface seismic imaging structural measurements and morphological analysis we show that this anticline is associated with two decollement levels we use kink band migration in growth strata dated by paleomagnetism to constrain the shortening from the mio pliocene to the holocene our results show that the dushanzi anticline has been active since at least 8 ma and that the fold grew at a steady shortening rate of 0 6 0 1 mm yr from 8 to 1 5 ma with possible variations from 2 5 to 1 5 ma then it accelerated rapidly to a rate of 4 3 1 0 mm yr over at least the last 100 ka these results together with similar temporal shortening evolutions across other structures suggest that the deformation rate across the eastern tianshan piedmont increased relatively recently this may reflect either a redistribution of the deformation from the internal structures toward the borders or a general acceleration of the deformation across the entire range

late miocene to quaternary slip history across the qiulitag anticline in the southern tianshan piedmont in this study we reconstruct the miocene to quaternary shortening history across the qiultag anticline a complex fault bend fold located in southern tianshan we studied the yaha and kuche sections where we combined surface structural measurements and seismic imaging to model the stratigraphic horizons the history of folding was reconstructed based on magnetostratigraphic analyses and eight cosmogenic burial ages in kuche pleistocene deformation rates were also quantified in yaha based on a deformed fluvial terrace that we dated to 67 ka using a cosmogenic depth profile our results suggest that the fold grew at a mean slip rate of 0 9 1 3 mm a in both sections but accelerated to 2 5 mm a during the pleistocene in kuche these results support a migration of the deformation toward the basin during the pleistocene and suggest that most of the present deformation of the tianshan is accommodated across the external structures of the range

dynamics stratigraphy and proximal dispersal of supraglacial tephra during the ice confined 2004 eruption at grimsvotn volcano iceland the basaltic phreatomagmatic eruption of grimsvotn volcano iceland in november 2004 g2004 lasted for 5 days during which time two separate vents were active significant deposition of tephra occurred in the first 45 h only we have subdivided the deposit into seven units a g on the basis of differences in texture grain size and componentry and the presence of sharp contacts between the layers the distribution of tephra lobes was used to infer the vent of origin for each unit the g2004 deposit is poorly sorted overall and consists of non vesicular to highly vesicular juvenile components units a and b comprise almost exclusively non to poorly vesicular glass fragments whereas units c g contain at least 30 vol highly vesicular pumice the proportion of non juvenile fragments increases significantly in the final unit unit f of the main phase non juvenile fragments are restricted to the coarse 0 fraction of the deposit main phase units c and e account for 80 of the total deposit volume including the entire distal portion and are interpreted to represent a mixture of 1 a widely dispersed component that fell from the upper margins of a strongly inclined 45 6 10 km high plume and 2 a locally dispersed 3 km from source component originating from pyroclastic density currents and minor tephra jets

infrared satellite observations of hydrogen sulfide in the volcanic plume of the august 2008 kasatochi eruption 1 hydrogen sulphide h2s is one of the main trace gases released from volcanoes with yearly global emissions estimated between 1 and 37 tg with sulfur dioxide so2 15 21 tg year it dominates the volcanic sulfur budget and the emission ratio h2s so2 is an important geochemical probe for studying source conditions sulfur chemistry and magma water interactions contrary to so2 measurements of h2s are sparse and difficult here we report the first measurements of a large h2s plume from space observations were made with the infrared sounder iasi of the volcanic plume released after the 7 8 august 2008 eruption of kasatochi volcano the eruption was characterized by 5 consecutive explosive events the first events were phreatomagmatic producing a plume rich in water vapor and poor in ash and so2 we show that the observed h2s plume calculated at 29 10 kt with integrated columns exceeding 140 25 dobson units du is likely associated with these first explosions h2s so2 ratios with maximum values of 12 2 are found representative of redox conditions in the hydrothermal envelop with a detection threshold of 25 du future space observations of h2s plumes are certain these will be important for improving the atmospheric sulfur budget and characterizing the h2s so2 fingerprint of different eruptions

reference data set of volcanic ash physicochemical and optical properties uncertainty in the physicochemical and optical properties of volcanic ash particles creates errors in the detection and modeling of volcanic ash clouds and in quantification of their potential impacts in this study we provide a dataset that describes the physicochemical and optical properties of a representative selection of volcanic ash samples from nine different volcanic eruptions covering a wide range of silica contents 50 80 wt sio2 we measured and calculated parameters describing the physical size distribution complex shape and dense rock equivalent mass density chemical bulk and surface composition and optical complex refractive index from ultra violet to near infrared wavelengths properties of the volcanic ash and classified the samples according to their sio2 and total alkali contents into the common igneous rock types basalt to rhyolite we found that the mass density ranges between 2 49 and 2 98 g cm3 for rhyolitic to basaltic ash types and that the particle shape varies with changing particle size d 100 m the complex refractive indices in the wavelength range between 300 nm and 1500 nm depends systematically on the composition of the samples the real part values vary from n 1 38 to 1 66 depending on ash type and wavelength and the imaginary part values from k 0 00027 to 0 00268 we place our results into the context of existing data and thus provide a comprehensive dataset that can be used for future and historic eruptions when only basic information about the magma type producing the ash is known

mesozoic and cenozoic tectonic history of the central chinese tian shan reactivated tectonic structures and active deformation 1 the present day topography of the tian shan range is considered to result from crustal shortening related to the ongoing india asia collision that started in the early tertiary in this study we report evidence for several episodes of localized tectonic activity which occurred prior to that major orogenic event apatite fission track analysis and u th he dating on apatite and zircon indicate that inherited paleozoic structures were reactivated in the late paleozoic early mesozoic during a cimmerian orogenic episode and also in the late cretaceous paleogene around 65 60 ma these reactivations could have resulted from the accretion of the kohistan dras arc or lithospheric extension in the siberia mongolia zone activity resumed in the late mesozoic prior to the major tertiary orogenic phase finally the ongoing deformation which again reactivates inherited tectonic structures tends to propagate inside the endoreic basins that were preserved in the range leading to their progressive closure this study demonstrates the importance of inherited structures in localizing the first increments of the deformation before it propagates into yet undeformed areas

geometry and kinematics of mykonos detachment cyclades greece evidence for slip at shallow dip 1 the eastern part of mykonos island cyclades greece shows the detailed internal structure of a two branch shallow dipping extensional detachment system of miocene age this paper shows that the last stage of slip along the detachment during the deposition of syn rift sediments occurred with a very low dip and proposes that this geometry prevailed since the initiation of extension extensional deformation during and after a 13 ma old granite intrusion is taken up by two main shallow dipping shear zones 1 the lower livada detachment which extends laterally across tinos island is a ductile structure located at the interface between the granite and the upper cycladic nappe metabasites a pervasive top to the ne shearing deformation is observed throughout the granite in this island with a strong gradient toward the intrusive contact later brittle faults shallowly and steeply dipping rework the ductile deformation with the same overall shear sense 2 the upper mykonos detachment is brittle and separates the metabasites from late miocene sandstones and conglomerates the detachment fault dips 12 15 toward the nne and its sense of shear is consistent with that of the livada detachment soft sediment deformation during the time of detachment faulting and the presence of steep normal faults that root into the detachment gouge indicate a shallow depth of deformation rotations about vertical and horizontal axes can be reconstructed within and below the detachment zone indicating that the overall direction of extension is nne ssw with a sense of shear toward the nne and the dip of the fault is throughout very low the two detachments have accommodated several tens of kilometers of horizontal extension during the formation of the aegean sea which emphasizes the importance of low angle extensional faults and shear zones in extensional tectonics

denudation intensity and control in the chinese tian shan new constraints from mass balance on catchment alluvial fan systems tectonics and climate are usually seen as the main controlling factors of denudation rates which seem to rise with the tectonic activity and to decrease when the climate becomes drier however the low denudation rates observed in semi arid to arid contexts are generally measured on orogenic plateaus where the respective influence of the flat relief and the dry climate cannot really be unravelled the chinese tian shan was chosen as a case study in the northern piedmont of this mountain range a series of well preserved quaternary alluvial fans offer the opportunity to perform a mass balance study at the scale of several catchment areas and several hundreds of thousands of years based on a geometrical reconstruction of these fans the volumes of sediments exported out of 10 drainage basins during the middle late pleistocene from 300 to 12 kyr and the holocene from 12 kyr to present have been estimated from these volumes an average denudation rate of 135 m myr was determined in the tian shan range for the last 300 kyr in agreement with other mass balances performed in the same area the typical denudation intensity of the northern tian shan is thus of a few hundred meters per million years at most regardless of the space and time scales considered from a comparison with denudation rates in other mountain ranges throughout the world we suggest that a dry climate can dramatically limit the denudation intensity even in active orogenic systems with a high topographic gradient like the tian shan as a result the time required to reach equilibrium between denudation and rock uplift in these systems could be extremely long i e of more than several million years copyright 2016 john wiley sons ltd

late cenozoic tectono geomorphologic evolution of the northern tian shan mountain range insight from u pb ages of detrital zircon grains from the upper oligocene quaternary sediments of the southern junggar basin abstract being one of the largest intra continental orogens of the world the tian shan orogenic belt was uplifted to its present elevation due to the far field effect of the india asia convergence in this study we performed a systematic study on the upper oligocene quaternary sedimentary rocks from the southern junggar basin including conglomerate clast counting and detrital zircon u pb dating to reconstruct the late cenozoic uplift history of the northern tian shan mountain range the new detrital zircon u pb data provide new constrains on the late cenozoic intra continental deformation of the borohoro range the yili central tian shan and north tian shan were the major sources for the junggar basin during the latest cretaceous paleogene period at that time the borohoro range was characterized by low topography and wide drainage pattern as the uplift of the north tian shan commenced at 25 23 ma the high topography of the northern borohoro range blocked the transport of sediments from the yili central tian shan to the north the north tian shan became the primary provenance area of the southern junggar basin according to sedimentary provenance analysis and geomorphologic survey we infer that the yili central tian shan started to uplift at 12 9 ma combined with previously published data our results suggest that the middle miocene uplift event most likely occurred in both the hinterland and foreland regions along the whole tian shan mountain range

uplift shortening and steady state topography in active mountain belts we present a tectonic surface process model used to investigate the role of horizontal shortening in convergent orogens and the effects on steady state topography the tectonic model consists of a specified velocity field for the earth9s surface and includes a constant uplift rate and a constant horizontal strain rate which varies to reflect the relative importance of frontal accretion and underplating in an orogenic wedge the surface process model includes incision of a network of rivers formed by collection of applied precipitation and diffusive hillslope mass transfer three non dimensional parameters describe this model a ratio of the maximum horizontal velocity to the vertical velocity a peclet number expressing the efficiency of the hillslope diffusion relative to the uplift rate and a fluvial erosion number reflecting the fluvial incision efficiency relative to the uplift rate a series of models are presented demonstrating the resultant steady state landforms parameterized by these three numbers a finite velocity ratio results in an asymmetric form to the model mountain range although the magnitude of the asymmetry also depends on the peclet number topographic steady state is achieved faster for models with no horizontal component to the velocity field with finite horizontal velocity topographic steady state is achieved only at the scale of the entire mountain range even the first order drainage basins are unstable with time in the presence of horizontal shortening we compare our model results to topographic profiles from active mountain ranges in taiwan new zealand and the olympic mountains of washington state all these examples exhibit asymmetric topographic form with the asymmetry consistent with the polarity of subduction suggesting that horizontal tectonic motion is affecting the macro geomorphic form of these ranges

limited impact of quaternary glaciations on denudation rates in central asia because of its essential role in coupling climate and tectonics denudation is a key parameter when constraining the history of earth s surface this is particularly true at the pliocene pleistocene transition and the potential impact of the onset of quaternary glaciations remains strongly debated in the present study we measured in situ cosmogenic 10be within continuous late cenozoic sedimentary sections that had already been dated using magnetostratigraphy the new data were obtained from four sedimentary basins in the northern and southern tianshan range central asia we first thoroughly discuss how in situ cosmogenic 10be concentrations can be corrected for radioactive decay and for the contribution of postdepositional cosmogenic accumulation to derive the paleo denudation rates our analysis shows that in the four sedimentary records the potential bias remains low enough to consider the derived denudation rates reliable the four records although likely influenced by local particularities due to lithological heterogeneity and local tectonics display similar trends of continuously increasing denudation between ca 9 ma and the present these rates have remained relatively high but steady since 4 ma 1 5 m y before the onset of the quaternary glacial cycles though the rejuvenation of the tianshan range since 11 ma may explain most of the progressive increase 5 in denudation our data suggest that the quaternary glaciations had only a limited impact on denudation in the tianshan our data however indicate an increase in the spatial and high frequency variability 1 m y of the denudation rates between 3 and 1 ma this may correspond to a transient readjustment of the landscape in response to the onset of quaternary glacial cycles

luminescence dating of the stratzing loess profile austria testing the potential of an elevated temperature post ir irsl protocol abstract feldspar infrared stimulated luminescence irsl signals saturate at 2000 gy i e 500 700 ka assuming a dose rate of 3 4 gy ka typical for loess and it is therefore theoretically possible to date middle pleistocene loess however the accuracy of age estimates is hampered by anomalous fading which leads to significant age underestimation fading corrections have been proposed but these corrections are reliant on inherent assumptions and in any case are inapplicable at large doses as the growth curve approaches saturation recent studies have identified a post ir irsl signal that shows less fading and is thus less dependent on accurate fading corrections this study builds upon these investigations and applies a post ir irsl sar dating protocol to polymineral fine grain samples of the loess palaeosol sequence in stratzing lower austria after a preheat at 320 c 60 s and an ir bleach at 50 c 200 s irsl was measured at 290 c for 200 s the same set of conditions were used to measure the response to a test dose recycling ratios recuperation and dose recovery tests show that this protocol is suitable for the loess under investigation although finite residual doses of up to 20 gy are observed for the oldest samples the natural signal is in or close to saturation indicating that fading is negligible in nature this observation is inconsistent with the measured laboratory fading rates of 1 1 5 decade and needs further investigation

new constraints on the late quaternary landscape evolution of the eastern tibetan plateau from 10be and 26al in situ cosmogenic nuclides abstract based on terrestrial cosmogenic nuclide tcn constraints from depth profiles of one granitic regolith from wumingshan and five fluvial terraces from xianshuihe and zagunao rivers we discuss the timing of the last deglaciation the landscape scale denudation and fluvial incision rates across the eastern tibetan plateau in relation to previous work we present a three dimensional graph visualization approach and corresponding constraints to better assess the feasibility and applicability of cosmogenic nuclides depth profile dating the exposure age older than 19 4 ka of the wumingshan regolith corresponds to the retreat of the palaeo daocheng ice cap which covered the yidun terrane during the last glacial maximum lgm most basin wide denudation rate data in the eastern tibetan plateau are lower than 130 mm ka 47 n 90 which is consistent with the wumingshan regolith denudation rate lower than 52 8 mm ka and thus indicate that the landscape scale denudation has been stabilized after the last deglaciation considering the reduction of integrated bulk density due to the accumulation of lower density loess we estimate mean exposure ages of xianshuihe and zagunao river terraces of 4 0 0 7 ka 5 9 0 3 ka 13 4 2 0 ka and 16 6 1 4 ka the observed increase in incision rate from 0 39 mm yr over long timescale 600 ka to 5 88 mm yr over the last 15 ka at the xianshuihe river site is probably due to the transition from glacial to interglacial climatic conditions the fewer abandoned terraces along the zagunao river after the heinrich event 1 h1 indicates that the climate change during the latest glacial interglacial transition impacted less the landscape evolution in a relatively lower elevation area comparison with previously reported fluvial incision rates elsewhere across the eastern margin of the tibetan plateau indicates that incision rates are mainly influenced by abrupt climate change or intensified summer monsoon since the early holocene but probably controlled by regional tectonic uplift or fluvial headward retreat as the timescale increases overall we propose a synthetic pattern of landscape evolution mainly dominated by long term tectonic uplift together with fluvial headward erosion episodically influenced by climatic change throughout the late quaternary

recent volatile evolution in the magmatic system of hekla volcano iceland estimates of the volatile budgets for volcanic eruptions are often based on volatile concentrations measured in melt inclusions mis versus groundmass glass here we present new measurements and estimates of pre eruptive volatile concentrations in magma from the hekla volcano in iceland based on mis in recent basalts and basaltic icelandites from the 2000 eruption the last eruption at hekla occurred from 26 february to 8 march 2000 it began with a short sub plinian phase followed by lava effusion that produced 0 17 km 3 of basaltic icelandite volatile s cl f and h2o and major element concentrations were measured in mis trapped in olivine and plagioclase phenocrysts contained in the basaltic icelandite from the 2000 eruption and in basalt erupted in 1913 from a fissure adjacent to the hekla volcano same elements were measured in the groundmass glass from the 2000 tephra the observed compositional range of mis from the basalt mgo 7 73 to the basaltic icelandite mgo 2 51 is readily explained by fractional crystallisation allowing the prediction of the evolution of dissolved volatile concentrations within the magma plumbing system beneath hekla the incompatible behaviour of the volatile elements controls their concentrations in mis during the crystal fractionation and consequently the highest concentrations are found in the most evolved basaltic icelandite mis with the notable exception of sulphur volatile concentrations in the basaltic mis exhibit strong linear correlations with k2o and this relationship can be used to estimate the theoretical expected volatile contents in the basaltic icelandite melt just prior to eruption such an approach avoids underestimation of the pre eruptive volatile contents measured in mis and improves constraints on the volatile mass release into the atmosphere the difference of volatile contents between expected concentrations and those present in the groundmass scaled to the mass of erupted magma yields maximum atmospheric mass loading of 0 10 mt hcl 0 17 mt hf and 3 77 mt so2 during the 2000 hekla eruption whereas calculations using the measured values in the inclusions give a significant lower mass yields of 0 05 mt hcl 0 17 mt hf and 0 6 mt so2 these results are discussed and compared to the data derived from remote sensing and snow proxy of the gas phase measurements 2007 elsevier b v all rights reserved

grain shape of basaltic ash populations implications for fragmentation here we introduce a new quantitative method to produce grain shape data of bulk samples of volcanic ash and we correlate the bulk average grain shape with magma fragmentation mechanisms the method is based on automatic shape analysis of 2d projection ash grains in the size range 125 63 m loose bulk samples from the deposits of six different basaltic eruptions were analyzed and 20 000 shape measurements for each were obtained within 45 min using the particle insight dynamic shape analyzer pidsa we used principal component analysis on a reference grain dataset to show that circularity rectangularity form factor and elongation best discriminate between the grain shapes when combined the grain population data show that the studied eruptive environments produce nearly the same range of grain shapes although to different extents our new shape index the regularity index ri places an eruption on a spectrum between phreatomagmatic and dry magmatic fragmentation almost vesicle free surtseyan ash has an ri of 0 207 0 002 2 whereas vesiculated hawaiian ash has an ri of 0 134 0 001 2 these two samples define the end member ri while two subglacial one lacustrine and another submarine ash sample show intermediate ris of 0 168 0 002 2 0 175 0 002 2 0 187 0 002 2 and 0 191 0 002 2 respectively the systematic change in ri between wet and dry eruptions suggests that the ri can be used to assess the relative roles of magmatic vs phreatomagmatic fragmentation we infer that both magmatic and phreatomagmatic fragmentation processes played a role in the subglacial eruptions

paleo erosion rates in central asia since 9 ma a transient increase at the onset of quaternary glaciations erosion is a fundamental player of the interactions existing between internal geodynamics and climate in particular through its influence on the carbon dioxide budget however long term 1 ma erosion rates estimated indirectly from sediment budget remain poorly constrained while some studies suggest that worldwide erosion rates increased at the plio pleistocene climatic transition 4 2 ma the validity of this observation and its significance is a matter of debate due to potential biases of the sedimentary record and to the influence of sea level fall on the global sedimentary flux to marginal basins in the present study we estimate erosion rates over the last 9 ma using in situ produced cosmogenic 10be concentrations measured in magnetostratigraphically dated continental sediments we focus on an intracontinental endorheic watershed draining the northern tianshan in central asia a key region regarding the ongoing debate while erosion rates between 0 1 and 1 mm yr 1 are derived from most of our record they reach values as high as 2 5 mm yr 1 from 2 5 to 1 7 ma then after 1 7 ma recent and modern erosion rates fell below 1 mm yr 1 this temporary increase is correlated with the onset of quaternary ice ages and suggests that global climate had a significant and transient impact on erosion

planation surfaces of the tian shan range central asia insight on several 100 million years of topographic evolution abstract in central asia numerous fragments of planation surfaces are visible within the present day topography however their precise timing of formations is still poorly constrained and it is not clear if they are remnants of a single extensive planation surface or if they represent different planation episodes by reconstructing the landscape evolution of the tian shan region and by analyzing the relations between the planation surfaces preserved within the eastern tarim basin and the sedimentary record we demonstrate that the numerous erosional surfaces preserved within the tian shan range represent different episodes of surfaces genesis these erosion events span from the late paleozoic to the early cenozoic the widespread preservation of large fragments of these surfaces within the tian shan range implies that this region did not undergo strong relief building during most of its mesozoic evolution but was dominated by plains associated to small hills along episodically active discrete tectonic structures finally the preservation of these surfaces within the active tian shan range implies a long term strong non equilibrium state of the topography during its cenozoic evolution this was probably promoted by the arid to semi arid climate prevailing since the late paleogene onset of relief building

active tectonics in southern xinjiang china analysis of terrace riser and normal fault scarp degradation along the hotan qira fault system the northern piedmont of the western kunlun mountains xinjiang china is marked at its easternmost extremity south of the hotan qira oases by a set of normal faults trending n50e for nearly 70 km conspicuous on landsat and spot images these faults follow the southeastern border of a deep flexural basin and may be related to the subsidence of the tarim platform loaded by the western kunlun northward overthrust the hotan qira normal fault system vertically offsets the piedmont slope by 70 m highest fault scarps reach 20 m and often display evidence for recent reactivations about 2 m high successive stream entrenchments in uplifted footwalls have formed inset terraces we have leveled topographic profiles across fault scarps and transverse abandoned terrace risers the state of degradation of each terrace edge has been characterized by a degradation coefficient derived by comparison with analytical erosion models edges of highest abandoned terraces yield a degradation coefficient of 33 4 m 2 profiles of cumulative fault scarps have been analyzed in a similar way using synthetic profiles generated with a simple incremental fault scarp model the analysis shows that 1 rate of fault slip remained essentially constant since the aggradation of the piedmont surface and 2 the occurrence of inset terraces was synchronous at all studied sites suggesting a climate driven terrace formation observation of glacial and periglacial geomorphic features along the northern front of the western kunlun range indicates that the qira glaciofluvial fan emplaced after the last glacial maximum during the retreat of the kunlun glaciers 12 22 ka the age of the most developed inset terrace in uplifted valleys is inferred to be 10 3 ka coeval with humid climate pulses of the last deglaciation the mass diffusivity constant k t being time b p in the hotan region is determined to be 3 3 1 4 m 2 10 3 years consistent with other estimates in similar climatic and geologic environments of western china these results imply a minimum rate for the tarim subsidence of 3 5 2 mm yr if western kunlun overthrusts the tarim platform on a crustal ramp dipping 40 45 to the south it would absorb at least 4 5 3 mm yr of convergence between western tibet and tarim

production of cosmogenic radionuclides at great depth a multi element approach abstract for the last two decades in situ produced cosmogenic nuclides are increasingly applied in earth sciences to quantify surface processes in parallel significant reduction of the analytical uncertainties linked to advances in accelerator mass spectrometry ams allows more precise measurements however among all the published works on cosmogenic nuclides only few studies are dedicated to a better understanding of their production systematic or to a better constrain of the physical parameters involved in their production thus an approach to investigate in situ produced cosmogenic nuclides 10 be 26 al and 36 cl along a single 11 meter long core drilled from the surface and composed of carbonates and quartzose conglomerates has been launched these measurements have been used to quantify muon induced productions based on natural samples for each studied nuclide contrary to the current most oftenly used calculation of muon induced production parameters which are based on irradiation experiments at discrete energies productions based on natural samples are considering the entire energy range of particles reaching the ground surface the evolution of 36 cl concentrations with depth needs to agree with those parameters deduced from 10 be and 26 al data this is optimized when considering a fast muon induced 36 cl production contribution and a spallation production rate at sea level high latitude slhl of 42 0 2 0 atoms 36 cl g ca 1 a 1 1 sigma uncertainty

major temporal variations in shortening rate absorbed along a large active fold of the southeastern tianshan piedmont china the investigation of deformation rates on a mountain piedmont can provide key information for improving our understanding of the overall dynamics of a mountain range here we estimate the shortening rate absorbed by a quaternary emergent detachment fold on the southeastern piedmont of the tianshan china our work is primarily based on new 10be cosmogenic exposure dating of deformed alluvial surfaces the method we have developed combines depth profiling with sampling of surface cobbles thereby allowing exposure time erosion rate and inheritance to be simultaneously constrained the exposure ages of the uppermost uplifted alluvial surfaces are around 140 17 ka140 17 ka 130 9 ka130 9 ka and 47 9 ka47 9 ka from west to east a terrace lying below the 140 ka surface is dated at 65 5 ka65 5 ka the ages of the uplifted and folded alluvial surfaces were then combined with estimates of shortening obtained using two distinct methods 1 the excess area method where sedimentation rates extracted from magnetostratigraphic studies are used to determine the amount of sedimentation after the abandonment of the river and 2 a folding model derived from sandbox experiments the late pleistocene shortening rates are shown to be between 0 4 0 1 mm yr0 4 0 1 mm yr and 0 8 0 5 mm yr0 8 0 5 mm yr on the western part of the fold and 2 1 0 4 mm yr2 1 0 4 mm yr along its central part the central part of the frontal yakeng anticline therefore accommodates up to 25 of the total shortening currently absorbed across the whole eastern tianshan range 8 mm yr however this situation seems to have prevailed for only the last 150 ka as the shortening rate absorbed by this nascent fold was previously ten times slower while the initiation of folding of the yakeng anticline can be traced back to 5 5 ma ago the basinward migration of the active deformation front onto the yakeng fold is a relatively recent phenomenon and appears to be diachronous from west to east probably in relation to the tectonic activity of the folds in the hinterland

initial incision of the jinshan gorge of the yellow river china constrained by terrestrial in situ cosmogenic nuclides chronology abstract how post burial terrestrial in situ cosmogenic nuclides tcn production is build up in slow burial condition remains uncertain in this study we dated high fluvial terrace sediments that overlain by loess with a slow deposition rate that is based on the assumption of steady accumulation rate via 26al 10be burial dating method for sample in deep and rapid buried condition prior to slow overlying post burial production shows low component 4 6 in measured concentration however post burial production occupied 39 79 of measured 26al and 10be concentrations which suggests approximately 0 2 0 3 ma underestimation in simple burial dating mode if post burial production is neglected corrected by post burial production we yielded burial ages of two top terraces ca 1 7 2 5 ma and 1 5 ma respectively below the tangxian planation surface along the jinshan gorge of the yellow river implying that the jinshan gorge initially incised at ca 1 7 2 5 ma corresponding well to regional tectonic activities such as extension in the fenwei graben accelerative uplift of the tangxian planation surface vigorous dissection of north china and significant tectonic deformation in northeastern tibetan plateau the slow burial mode is probably a potential method for plateau paleo elevation estimation taking advantage of height sensitivity of tcn production rate if overlying loess magnetostratigraphic age is known

elevated gas flux and trace metal degassing from the 2014 2015 fissure eruption at the barðarbunga volcanic system iceland the 2014 bar arbunga rifting event in iceland resulted in a 6 month long eruption at holuhraun this eruption was characterized by high lava discharge rate and significant gas emission the so2 flux for the first 3 months was measured with satellite sensors and the petrologic method high resolution time series of the satellite data give 1200 kg s that concurs with 1050 kg s obtained from melt inclusion minus degassed lava sulfur contents scaled to the mass of magma produced a high purity gas sample with elevated s cl due to limited chlorine degassing reveals a similar degassing pattern of trace metals as observed at k lauea hawai i and erta ale ethiopia this suggests a common degassing mechanism at mantle plume related volcanoes the trace metal fluxes calculated from trace element to sulfur ratios in the gas sample and scaled to the sulfur dioxide flux are 1 2 orders of magnitude stronger at holuhraun than k lauea and erta ale in contrast volcanoes at convergent margins etna and stromboli italy have 1 2 orders of magnitude higher trace element fluxes most likely caused by abundant chlorine degassing this emphasizes the importance of metal degassing as chlorine species short lived disequilibria between radon daughters 210pb 210bi 210po measured in the gas suggest degassing of a continuously replenished magma batch beneath the eruption site earlier and deep degassing phase of carbon dioxide and polonium is inferred from low 210po 210pb in the gas consistent with magma transfer rate of 0 75 m s

denudation rates determined from the accumulation of in situ produced 10be in the luquillo experimental forest puerto rico we present a simple method for estimation of long term mean denudation rates using in situ produced cosmogenic 10be in fluvial sediments procedures are discussed to account for the effects of soil bioturbation mass wasting and attenuation of cosmic rays by biomass and by local topography our analyses of 10be in quartz from bedrock outcrops soils mass wasting sites and riverine sediment from the icacos river basin in the luquillo experimental forest puerto rico are used to characterize denudation for major landform elements in that basin the 10be concentration of a discharge weighted average of size classes of river sediment corresponds to a long term average denudation of 43 m ma 1 consistent with mass balance results

modeling the shortening history of a fault tip fold using structural and geomorphic records of deformation 1 we present a methodology to derive the growth history of a fault tip fold above a basal detachment our approach is based on modeling the stratigraphic and geomorphic records of deformation as well as the finite structure of the fold constrained from seismic profiles we parameterize the spatial deformation pattern using a simple formulation of the displacement field derived from sandbox experiments assuming a stationary spatial pattern of deformation we simulate the gradual warping and uplift of stratigraphic and geomorphic markers which provides an estimate of the cumulative amounts of shortening they have recorded this approach allows modeling of isolated terraces or growth strata we apply this method to the study of two fault tip folds in the tien shan the yakeng and anjihai anticlines documenting their deformation history over the past 6 7 myr we show that the modern shortening rates can be estimated from the width of the fold topography provided that the sedimentation rate is known yielding respective rates of 2 15 and 1 12 mm yr across yakeng and anjihai consistent with the deformation recorded by fluvial and alluvial terraces this study demonstrates that the shortening rates across both folds accelerated significantly since the onset of folding it also illustrates the usefulness of a simple geometric folding model and highlights the importance of considering local interactions between tectonic deformation sedimentation and erosion

mechanisms of active folding of the landscape southern tian shan china 1 we explore the kinematic mechanisms of active large scale folding based on analysis of two adjacent major anticlines in tian shan central asia that share an acceleration of shortening rate leading to topographic emergence and folded geomorphic surfaces their folding mechanisms are fundamentally different yakeng anticline is a gentle pure shear detachment fold with 1200 m of shortening and a well constrained history of growth beginning at 5 5 ma with an order of magnitude increase in shortening rate from 0 16 to 1 2 1 6 mm yr at 0 16 0 21 ma the shape of the deformed topographic surface and of subsurface horizons deposited during deformation is a linearly proportional image at reduced amplitude of the deeper structure which shows that instantaneous uplift rates have been pointwise linearly proportional to the current finite fold amplitude in contrast quilitak anticline is a complex fault bend fold with uplift rates proportional to the sine of the fault dip showing discontinuities in uplift rate across active axial surfaces the 10 to 20 km wide anticline is topographically emergent only in a central 5 to 7 km wide mountainous uplift the abrupt southern edge of which is marked by 600 to 700 m high triangular facets that result from active folding of a pediment across an active axial surface the giant facets are shown to form by kink band migration and record postemergence deformation since an order of magnitude acceleration in shortening rate from 0 6 to 4 5 mm yr apparently contemporaneous with yakeng sections logged across the active 115 m wide hinge zone show that recent strata provide a bed by bed record of fold scarp growth which is quantitatively deciphered by fitting bed shapes to a finite width kink band migration model

erosion as a driving mechanism of intracontinental mountain growth in nature mountains can grow and remain as localized tectonic features over long periods of time 10 m y by contrast according to current knowledge of lithospheric rheology and neglecting surface processes any intracontinental range with a width that exceeds that which can be supported by the strength of the lithosphere should collapse within a few tens of millions of years for example assuming a quartz dominated crustal rheology the relief of a range initially 3 km high and 300 400 km wide is reduced by half in about 15 m y as a result of lateral spreading of its crustal root we suggest that surface processes might actually prevent such a subsurface collapse removal of material from topographic heights and deposition in the foreland oppose spreading of the crustal root and could eventually drive a net influx of material toward the orogeny we performed a set of numerical experiments in order to validate this hypothesis a section of a lithosphere with a brittle elasto ductile rheology initially loaded by a mountain range is submitted to horizontal shortening and to surface processes if erosion is intense material is removed more rapidly than it can be supplied by crustal thickening below the range and the topography is rapidly smoothed for example a feature 3 km high and 300 400 km wide is halved in height in about 15 m y for an erosion coefficient k 10 3 m 2 yr the erosion rate is of the order of a few 0 1 mm yr this regime might be called erosional collapse if erosion is not active enough the crustal root spreads out laterally and subsurface collapse occurs in the third intermediate regime removal of the material by erosion is dynamically compensated by isostatic rebound and inward flow in the lower crust so that the range can grow in this mountain growth regime the range evolves toward a characteristic graded shape that primarily depends on the erosion law the erosion rate may be high e g 0 5 0 9 mm yr close to the rate of tectonic uplift e g 0 7 1 1 mm yr and few times higher than the rate of topographic uplift 0 15 0 2 mm yr these experiments show that surface processes can favor localized crustal shortening and participate in the development of an intracontinental mountain surface processes must therefore be taken into account in the interpretation and modeling of long term deformation of continental lithosphere conversely the mechanical response of the lithosphere must be accounted for when large scale topographic features are interpreted and modeled in terms of geomorphologic processes

the thermo hydro mechanical behavior of the argillaceous cobourg limestone the cobourg limestone is a low permeability argillaceous rock that forms a part of the paleozoic sedimentary sequence found in southern ontario canada the limestone has a heterogeneous fabric consisting of nodular regions of calcite and dolomite and argillaceous partings of a similar composition but with a low clay content which gives the appearance of nominal stratifications the thermo hydro mechanical thm behavior of the rock is of interest to the proposals for using sedimentary formations as candidate rocks for siting deep geological repositories for the storage of heat emitting nuclear fuel waste the paper presents the results of experiments where thm processes were initiated in an intact cylindrical sample of the cobourg limestone containing a central cylindrical fluid filled cavity biot s classical theory of poroelasticity extended to include thermal effects is used to examine the thm response of the fluid cavity due to boundary heating of the cylinder the rise and decay of thermally induced cavity fluid pressure is used to examine the applicability of the thm modeling the experiments were conducted on cylindrical samples of the cobourg limestone with their axes either along or normal to the nominal planes of the argillaceous partings

remote sensing of volcanoes and volcanic processes integrating observation and modelling introduction volcanoes are often remote and have footprints that may extend across many hundreds or thousands of square kilometres they are generally inaccessible during eruption and may continue to be inaccessible for extended periods of time after eruption while their products can be scattered or dispersed over regional or global scales consequently since direct measurement can only provide us with part of the picture of many volcanic processes remote sensing is now playing an increasingly important role in advancing understanding of the science underlying volcanic behaviour on this planet and beyond e g mouginis mark et al 2000 sparks et al 2012 satellite airborne and ground based remote sensing are increasingly vital tools for monitoring active or potentially active volcanoes and assessing their likely real time or time averaged impact fig 1 at the same time the synoptic scale surveys that are often well suited to remote sensing techniques allow us to address questions about the fundamental processes that control volcano behaviour in a way that is not necessarily possible from individual case studies new research is often driven by technological advancements in the development of novel sensors or launching of new platforms meaning that the space agencies are increasingly involved in identifying scientific questions and priorities e g ferruci et al 2012 multiple and complementary data streams are increasingly being used both to monitor active volcanoes and advance volcanological science the key geophysical parameters that comprise monitoring data streams typically include the categories of i seismicity ii surface deformation iii thermal measurements and iv gas flux and composition data as major components while measurements of seismicity remain the domain of ground based seismometers remote sensing techniques have made major contributions in each of the others this special publication volume is concerned with the use of remote sensing at volcanoes it is split into three parts roughly arranged from the subsurface to the surface and then further afield as volcanic products are injected and dispersed into the atmosphere the papers span a range of applications of remote sensing techniques to monitor and understand a surface deformation b surface thermal anomalies and c gas fluxes as well as tracking ash and gas plumes from eruptions to gain insights into the extent of a volcano s impacts volcanology is driven in part by the operational concerns surrounding volcano monitoring and hazard and crisis management but the goal of volcanological science is at its heart to understand the processes that underlie volcanic activity this special publication is also concerned with how we go from observations to this deeper understanding including the progress that can be made by integrating observations and modelling while this volume focuses mainly on satellite based remote sensing integrating datasets from different platforms is also of vital importance and so papers on airborne remote sensing and measurement from both manned and unmanned aircraft are also included

spatiotemporal patterns of the late quaternary deformation across the northern chinese tian shan foreland abstract the investigations of active deformation across a mountain foreland can provide important insights into the pattern and dynamics of deformation of an active orogenic belt here we focus on the spatiotemporal patterns of the late quaternary deformation along the north piedmont of the chinese tian shan a mountain range formed by the ongoing india asia collision by using a terrace as the reference and applying the area conservation method the holocene shortening rate of the halaande anticline a fold of the distal structure belt iii in the foreland is estimated to 2 14 0 24 mm yr for the first time similarly we re calculate the holocene shortening rates of the other anticlines of belt ii iii using the magnitude of shortening documented by river terraces and the terrace formation ages published previously the summed holocene 103 year timescale shortening rates of individual anticlines along n s transects are 2 4 mm yr consistent with the late pleistocene 104 year timescale shortening rate but about 2 6 times higher than the long term 106 year timescale average shortening rate of 1 mm yr during the past several million years together with the shortening rates of individual anticlines at the 103 year 104 year and 106 year scales these observations imply that the deformation across the northern chinese tian shan foreland has accelerated since at least late pleistocene by summing the late quaternary rates of shortening in the southern chinese tian shan foreland 4 5 mm yr and the intermontane basins in the hinterland of the tian shan 2 mm yr the late quaternary rate of shortening across the tian shan range between longitude 83 e and 87 e amounts to 9 0 1 0 mm yr approximately matching the modern shortening rate of 8 mm yr derived from the gps measurements these results imply i that the deformation across the tian shan range and its foreland basins between longitude 83 e and 87 e could have not been changed significantly since at least late pleistocene ii that in the northern chinese tian shan foreland the recurrence interval of paleoseismic events during the past tens of thousands of years may be determined by a linear extrapolation of the holocene or even geodetic rate of deformation

dry early holocene revealed by sand dune accumulation chronology in bayanbulak basin xinjiang nw china understanding the holocene climate changes especially moisture variation and their mechanisms in the semiarid arid central asia sca is very important as water availability is crucial for sustainable developments in this area this study presents chronostratigraphy of an aeolian sedimentary sequence from bayanbulak basin xinjiang nw china aiming to infer the holocene moisture history in the sca luminescence dating technique was selected to construct the age framework of the study section since the luminescence signal intensity of quartz from the samples was too low to be detected feldspar was used as an alternative dosimeter a newly developed post infrared ir ir stimulated luminescence irsl pirir dating protocol on k feldspar was applied to determine the ages of samples a set of tests on luminescence characteristics was performed and demonstrate that this method is suitable and the resultant ages are reliable combined with the stratigraphic investigation on the sand dune palaeosol section the results imply a very dry climatic condition characterized by sand dune accumulation at similar to 9 8 kyr and a wet interval of 5 1 6 kyr when a soil layer was formed this moisture variation pattern is consistent with that inferred from many lacustrine records in the sca suggesting a widespread dry period at 11 8 kyr the present results appear to challenge a new stalagmite delta o 18 sequence located nearby to bayanbulak basin which instead suggested a humid early holocene

late cretaceous palaeogene topography of the chinese tian shan new insights from geomorphology and sedimentology abstract the cenozoic growth of the intra continental tian shan range initiated during the late eocene oligocene and led to a tectonic reactivation of the complex palaeozoic and mesozoic lithospheric structure due to the very low erosion rates linked to the semi arid climate that characterised the tian shan region during most of the cenozoic the topography of the range is not at equilibrium with deformation fragments of pre orogenic low relief surfaces are preserved among the late cenozoic alpine type topography using field observations and satellite image mapping of those fragments as well as sedimentology and biostratigraphic analysis we show that the pre oligocene topography of the tian shan region was indeed complex combining hundreds of metres to one and a half kilometre high reliefs with a multi phased mesozoic planation surface incised by late mesozoic paleo valleys the occurrence of several metres thick late cretaceous palaeogene calcareous paleosols in the basins surrounding the range further implies a semi arid climate very low subsidence rates and no uplift at that time late cretaceous and early miocene fossil records in the northern tian shan suggest a possible connection even if episodic between the drainage system of the south junggar foreland basin and the proto paratethys sea to the west a renewed late eocene early oligocene sedimentation probably marks the onset of the tian shan uplift we argue that in addition to the growth of the pamir and western kunlun ranges this incipient uplift was one of the driving mechanisms for the final retreat of the proto paratethys sea from the tarim basin this regression apparently did not change the climate in the studied area because semi arid conditions seem to prevail at least since the late cretaceous finally the tian shan uplift remained very limited up to the miocene as revealed by the occurrence of burdigalian lake deposits preserved in the paleo valleys inside the present day range in contrast post early miocene deformation of the northern tian shan has produced 4000 to 5000 m of differential vertical movement between the uplifted range and the subsiding proximal foreland basin

climatically controlled formation of river terraces in a tectonically active region along the southern piedmont of the tian shan nw china abstract combined tectonic uplift and quaternary climate variability control the deposition and abandonment of terraces along the southern tian shan in northwest china several preserved terraces have been deformed by an actively growing anticline within the uplifted frontal thrust system of the southern tian shan we combine geomorphic mapping topographic surveys of the deformed terrace surfaces 10be terrestrial cosmogenic nuclide tcn depth profile dating and optically stimulated luminescence osl dating to develop a new chronology for the terraces along the huangshui he since 550 ka our in situ 10be dating of fluvial gravels capping strath terraces suggests a relationship between the formation and abandonment of the terraces and glacial climate cycles since the middle late pleistocene these data indicate that the formation of the four terraces occurred at 550 430 350 and 60 ka we suggest that episodes of aggradation were facilitated by high sediment supply during glacial periods followed by subsequent incision that led to abandonment of these terraces during deglaciation we also estimate that tectonically induced river incision may account for about 60 70 of the total incision however during the intervening time between 350 ka and present only one terrace was formed and preserved we suggest that this record might be caused by a gradually decreasing uplift rate of the anticline through time and thus has influenced the preservation of terraces therefore our results demonstrate the utility of chronologic records from southern tian shan for deconvolving the effects of tectonics and climate on fluvial incision

holocene volcanic activity at grimsvotn bardarbunga and kverkfjoll subglacial centres beneath vatnajokull iceland assessment of potential future eruptive behaviour of volcanoes relies strongly on detailed knowledge of their activity in the past such as eruption frequency magnitude and repose time the eruption history of three partly subglacial volcanic systems grimsvotn bardarbunga and kverkfjoll was studied by analysing tephra from soil profiles around the vatnajokull ice cap which extend back to 7 6 ka well known regional holocene marker tephra e g h3 h4 h5 were utilized to correlate profiles stratigraphic positions and geochemical compositions were used for fine scale correlation of basaltic tephra around vatnajokull ice cap 345 tephra layers were identified of which 70 originated from grimsvotn bardarbunga or kverkfjoll the eruption frequency of each volcanic system was estimated grimsvotn has been the most active with an average of 7 eruptions 100 years range 4 14 during prehistoric time before 870 ad bardarbunga has been the second most active with 5 eruptions 100 years range 1 8 and kverkfjoll has remained essentially calm with 0 3 eruptions 100 years but showing periodic activity with repose times of 1000 years all three volcanic systems experienced lulls in activity from 5 ka to 2 ka referred to as the mid holocene low this reduced eruption frequency appears to have resulted from a decrease in magma generation and delivery from the mantle plume rather than from changes in ice load glacier thickness in prehistoric time there was a time lag of 1000 3000 years between a peak of activity at volcanoes directly above the mantle plume versus at volcanoes located in the non rifting part of the eastern volcanic zone closer to the periphery of the island this time space relationship suggests that a significant future increase in volcanism can be expected there following increased levels of volcanism above the plume

miocene to present kinematics of fault bend folding across the huerguosi anticline northern tianshan china derived from structural seismic and magnetostratigraphic data we combine surface structural measurements subsurface seismic imaging and magnetostratigraphic dating to retrieve through geometric modeling the detailed history of fold growth and sedimentation across the huerguosi anticline on the northern tianshan piedmont taking advantage of a beautifully exposed section of growth strata the model assumes a fault bend folding mechanism consistent with subsurface fold geometry the shortening history is obtained by least squares fi tting of the measured dip angles of the growth strata the shortening rate across the anticline is shown to have been remarkably constant it increased only slightly from 0 84 0 04 mm yr between 10 and 4 ma to 1 14 0 02 mm yr over the past 4 m y this approach also allows correcting syntectonic sedimentation rates for the effect of the fold growth and shows that the sedimentation rates in the piggyback basin increased abruptly from 0 4 to 0 7 mm yr ca 4 ma

denudation outpaced by crustal thickening in the eastern tianshan the modern high topography of the tianshan resulted from the reactivation of a paleozoic orogenic belt by the india asia collision today the range exhibits tectonically active forelands and intermontane basins based on quantitative morphotectonic observations and age constraints derived from cosmogenic 10be dating single grain post infrared infrared stimulated luminescence p ir irsl dating and modeling of fault scarp degradation we quantify the deformation in the nalati and bayanbulak intermontane basins in the central eastern tianshan our results indicate that at least 1 4 mm yr of horizontal crustal shortening is accommodated within these two basins this shortening represents over 15 of the 8 5 0 5 mm yr total shortening rate across the entire range at this longitude this shortening rate implies that the eastern central tianshan is thickening at a mean rate of 1 4 mm yr a rate that is significantly higher than the average denudation rate of 0 14 mm yr derived from our cosmogenic analysis this discrepancy suggests that the tianshan range has not yet reached a steady state topography and remains in a transient state of topographic growth most likely due to limited denudation rates driven by the arid climate of central asia

the sulfur budget of the 2011 grimsvotn eruption iceland 1 sulfur concentrations have been measured in 28 melt inclusions mis in plagioclase clinopyroxene and olivine crystals extracted from tephra produced during the explosive eruption of grimsvotn in may 2011 the results are compared to sulfur concentrations in the groundmass glass in order to estimate the mass of sulfur brought to surface during the eruption satellite measurements yield order of magnitude lower sulfur 0 2 tg in the eruption plume than estimated from the difference between mi and the groundmass glass this sulfur deficit is readily explained by sulfur adhering to tephra grains but principally by sulfide globules caused by basalt sulfide melt exsolution before degassing a mass balance calculation reveals that approximately 0 8 tg of so2 is present as globules representing 50 of the total sulfur budget most of the sulfide globules likely reside at depth due to their elevated density for potential later remobilization by new magma or hydrothermal circulation

dating fluvial terraces with and profiles application to the wind river wyoming abstract fluvial strath terraces provide a record of river incision and the timing of climatic perturbations to the fluvial system dating depositional surfaces like terraces that are older than the range of 14 c however is difficult we employ a cosmogenic radionuclide crn profile technique that addresses a major problem of crn dating on such surfaces nuclide inheritance by measuring 10 be and 26 al profiles we constrain the exposure age and the mean crn inheritance for the deposit the crn profile also yields a self check on the assumptions underlying the method we report our attempts to date terraces along the wind river wy like many sequences of western north american fluvial terraces these are inferred to reflect oscillation between glacial and interglacial conditions in the headwaters previous dating of some of these terraces and the associated terraces and glacial deposits makes this a unique location to compare dating methods dates from five sites along the bull lake glacial correlative terrace wr 3 are 118 125 ka which agrees with dates on bull lake age moraines and independent age estimates on the terrace and is consistent with the model of terrace glacial relationship crn inheritance is significant and highly variable requiring it be considered despite the additional sampling complexity assuming all inheritance in wr 3 deposits arises during exhumation in the headwaters we obtain minimum mean rates of exhumation of 13 130 m my for the source rocks alternatively assuming the crns are inherited during clast transport the time of fluvial transport from source to terrace is 10 ka it increases downstream and is lower for sand than cobbles the crn ages for older terraces wr 7 300 ka and wr 15 510 ka are lower by 50 than previous estimates based on tephrochronology the most plausible explanation is eolian deflation of a once thicker loess cover on the terrace surfaces mean thicknesses of loess of 0 5 1 5 m are required to reconcile these concentrations of crn with the previous estimates of age difficulty in dating the older terraces emphasizes that geologic caution independent estimates of age and multiple sample sites should still be part of dating depositional surfaces with crns even when employing the inheritance correction technique

calculation of the cosmogenic nuclide production topographic shielding scaling factor for large areas using dems the recent surge of applications using terrestrial cosmogenic nuclides tcns to calculate catchment averaged erosion rates from isotopic concentrations in fluvial sediment and the prospect of coupling tcn production functions with numerical surface process models spms necessitate a fast and accurate algorithm for the calculation of topographic shielding topographic shielding refers to the proportion of the incoming cosmic radiation that is shielded by the surrounding topography the scaling factor being defined as the ratio of the unshielded total minus shielded to the total or maximum cosmic ray flux i e the flux received by a horizontal unobstructed surface topography contributes to the reduction of tcn production by obstructing a certain proportion of the incoming flux and by modifying the angle of incidence available algorithms calculate the proportion of obstructed radiation by dividing the horizon as seen by the sample a grid cell in the case of a dem into arc segments usually of equal length for which the average obstruction heights expressed as zenith angles are calculated the use of these methods is feasible only when dealing with a small number of isolated samples since the identification of obstructions when dealing with an entire area is computationally very intensive this paper describes a method that uses a relief shadow modelling technique to identify those areas of a dem that are under shadow i e shielded and thus to account for the obstructed radiation this method produces results that are very similar to those obtained using a direct implementation of available methods maximum difference between results of c 0 1 the method based on relief shadow modelling is also faster than a direct implementation of any available method and can be readily implemented in any gis system with raster capabilities copyright 2006 john wiley sons ltd

volatile fluxes integrated over four decades at grimsvotn volcano iceland samples of the subglacial lake in the crater of the tholeiitic basaltic caldera grimsvotn in iceland were obtained by using a hot water drill to sink two boreholes through the 250 m thick ice shelf covering the lake the lake generally shows an increase in solutes with increased depth as solutes are added from the lake s bottom and dilute glacial meltwater is added continuously from above the crater lake temperature ranges from 0 c in the upper part to temperatures of 1 c to 4 c near the bottom of the lake the lake water ph ranges between 7 0 and 5 7 the crater lake is assumed to be closed with respect to volatile components released from subsurface magma except for periodic draining by jokulhlaups from the periodicity and water chemistry of the jokulhlaups we have estimated the volcano s average release rates of carbon sulfur chlorine and fluorine between 1954 and 1991 and corrected these rates for dissolution of bedrock into the lake water and seepage of solutes to groundwater the corrected mean release rates are 5 3 107 kg c yr 1 5 3 106 kg s yr 1 6 6 105 kg cl yr 1 and 1 5 105 kg f yr 1 the emission rate estimates for grimsvotn one of the most active volcanoes in iceland are the longest integrated estimates obtained for an active volcano and are equal to or lower than those of other major active volcanoes worldwide this difference may imply that published release rates for other volcanoes are overestimated because they are usually not integrated over time the values of the s cl and f cl ratios for noneruptive periods are 0 53 0 20 and 0 013 0 003 and for the two eruptive events are 0 69 and 2 14 and 0 034 and 0 041 respectively the response of the elemental ratios to eruptive events followed by the return to lower ratios supports the assumption of steady state because no long term accumulation of volatiles occurs the energy output from the volcano estimated from the amount of ice melted by hydrothermal heat is 4250 mw over the last four decades using the energy output to calculate magma solidification rates and maximum possible volatile release rates we observe that emissions of f and s are strongly suppressed at grimsvotn while a significant portion of available cl and c are released these calculations also reveal that coverage of a volcano by a glacier and subsequent raising of the water table may cause significant scrubbing of magmatic gases so that these gases do not reach the atmosphere

evolution of permeability in sand injectite systems abstract sand injectite complexes comprise kilometer scale clastic intrusion networks that act as effective conduits for the migration accumulation and then recovery of hydrocarbons and other fluids an equivalent continuum model is constructed to represent a sand injectite reservoir coupling stress and fluid flow in fractured rock using the continuum simulator toughreact coupled with flac3d to follow deformation and fluid flow a permeability model which uses staged percolation models is proposed to improve permeability estimation of fracture networks by accommodating four different levels of fracture connectivity this permeability model is confirmed against field and laboratory data corresponding to the different connectivities of fracture networks the new constitutive permeability model is incorporated into the coupled hydro mechanical simulator framework and applied to sand injectites with the analysis of permeability evolution mechanisms and mechanical sensitivity the results indicate that when the magnitudes of principal stresses increase in a constant ratio normal closure is the dominant mechanism in reducing fracture aperture and thereby permeability conversely the evolution of stress difference can accentuate aperture and permeability due to an increase in shear dilation for critically or near critically oriented fractures also the evolution of aperture and related permeability of fractured rock are more sensitive at lower stress states than at higher stress states due to the hyperbolic relationship between normal stress and normal closure of the fractures

origin and fate of sulfide liquids in hotspot volcanism la reunion pb isotope constraints from residual fe cu oxides immiscible sulfide liquids in basaltic magmas play an important role in trace metal transport and the sulfur budget of volcanic eruptions however sulfides are transient phases whose origin and fate are poorly constrained we address these issues by analyzing sulfide destabilization products preserved in lavas from la reunion island iron oxide globules and coatings typically 20 80 m in size were found to occur in vesicles of differentiated lavas from piton des neiges and recent pumice samples from piton de la fournaise field and mineralogical evidence indicates that the iron oxides are syn eruptive phases not resulting from hydrothermal processes samples were first studied by scanning electron microscopy the globules were separated whereas the smaller spherules and coatings were concentrated by magnetic sorting and acid leaching and samples were processed through wet chemistry the fe oxide phases comprise 49 74 wt fe 26 40 wt o and up to 6 wt cu 811 ppm ni 140 ppm bi and 8 5 ppm pb compared to the host lava cu ni and bi are enriched by a factor of 101 103 systematic pb isotope disequilibrium between 500 ppm and 2 9 for 206pb 204pb exists between fe oxides and host rocks with fe oxides generally displaying less radiogenic ratios unradiogenic pb is a typical signature of sulfide which tends to concentrate pb but not its parent elements u and th thus both the chemical and isotopic compositions of the vesicle hosted fe oxides suggest that they are more or less direct products of the destabilization of immiscible sulfide liquids although pb dominantly partitions into the gas phase during sulfide breakdown the original pb isotope signature of sulfide is preserved in the residual oxide the composition estimated for the parent sulfides 206pb 204pb 18 20 18 77 207pb 204pb 15 575 and 208pb 204pb 38 2 38 8 precludes a genetic link with the la reunion plume and suggests a lithospheric or crustal origin it is estimated that magma ascent velocities at piton de la fournaise are high enough to counterbalance the settling velocities of millimeter size sulfides despite their high density sulfide liquids are thus transferred upward during eruptions and their destabilization contributes to so2 emanations assimilation of foreign sulfides from the lithosphere can explain why so2 emissions sometimes e g during the april 2007 eruption exceed those predicted from the s content of melt inclusions