volcano and climate driven changes in atmospheric dust sources and fluxes since the late glacial in central europe atmospheric dusts are an important part of the global climate system and play an important role in the marine and terrestrial bio geochemical cycles of major and trace nutrient elements a peat bog record of atmospheric deposition shows considerable variation in dust deposition during the past 15 k y with abrupt changes in fluxes at 12 9 2 8 4 7 2 and 6 cal kyr b p using nd isotopes and rare earth elements it is possible to clearly distinguish between volcanic inputs and those driven by climate change such as the long term aridification of the sahara and regional erosion due to forest clearing and soil cultivation activities our results indicate that a major dust event in north africa and europe preceded the 8 2 kyr b p cold event by 200 yr this dust event may have played an active role in the following climate cooling of the 8 2 kyr b p event nd isotope evidence also indicates a relatively slow change in dust regime over europe from 7 to 5 kyr b p due to sahara expansion these fi ndings show that the inorganic fraction in high resolution peat records can provide remarkably sensitive indicators of dust load and sources our study supports the priority to better identify the impact of dust loading during the holocene in terms of direct and indirect impacts on environmental and climate changes

saharan aeolian input and effective humidity variations over western europe during the holocene from a high altitude record saharan dust inputs affect present day ecosystems and biogeochemical cycles at a global scale previous saharan dust input reconstructions have been mainly based on marine records from the african margin nevertheless dust reaching western central europe is mainly transported by high altitude atmospheric currents and requires high altitude records for its reconstruction the organic and inorganic geochemical study of sediments from a southern iberia alpine lacustrine record has provided an exceptional reconstruction of saharan dust impact and regional climatic variations during the holocene after the last deglaciation results indicate that saharan dust reached western europe in a stepwise fashion from 7 0 to 6 0 cal kyr bp and increased since then until present promoting major geochemical changes in the lacustrine system effective humidity reconstruction indicates wetter conditions during the early holocene and progressive aridification during middle late holocene time boosting abrupt changes in the lacustrine system cyclostratigraphic analyses and transport mechanisms both point to solar irradiance and aridity as major triggering factors for dust supply over western europe during the holocene

last 1000 years of environmental history in southern bucovina romania a high resolution multi proxy lacustrine archive geo ecological and landscape change studies at a local scale are scarce in central eastern europe and particularly in romania however this focus is directly relevant to ecosystems and humans as both are dependent on local environmental changes we perform a high resolution multi proxy analysis of physical and geochemical sediment properties coupled to plant macrofossil pollen and charcoal analysis at iezerul sadovei lake and present the first palaeoenvironmental reconstruction from bucovina mountains the north eastern romania the sedimentary record spanning the last 950 years is laminated throughout and reveals high intensity catchment responses to changes in hydrological conditions and human impact results show major landscape disturbances 950 years ago and during the last 200 years the enhanced catchment instability from the onset of sedimentation to 1400 ce was characterised by landsliding and subsequent erosion and related mainly to natural factors however the most recent since c 1800 ce environmental changes i e deforestation enhanced channel and slope erosion and lake in filling are a consequence of direct human interventions changes in the composition and extent of forest cover were also driven by the combination of natural disturbances climate variability and anthropogenic activities from 1400 ce and more clearly over the last 200 years early successional and disturbed habitat taxa appeared to respond primarily to anthropogenic drivers including forest management the higher proportion of abies alba 30 and fagus sylvatica 20 in the local forest and their dramatic decline was recorded earlier i e 1150 ce and 1400 ce respectively than reported in other parts of the romanian carpathians using this palaeoenvironmental evidence as an analogue projected climate changes i e increased seasonal heavy precipitation and more frequent extreme events superimposed on increasing human pressure are likely to lead to the destabilisation of the catchment through erosion and possible reactivation of landslides

late cenozoic tectonic evolution of the northwestern tien shan new age estimates for the initiation of mountain building the tien shan are the quintessential intracontinental range situated more than 1000 km north of the suture between india and asia their initiation and growth in the cenozoic however remain poorly understood in this study we present stratigraphic detrital fission track and magnetostratigraphic results that provide a basis for reconstructing the cenozoic tectonic evolution of the kyrgyz range and adjacent chu basin in the northwestern tien shan detrital fission track thermochronology indicates that the northwestern tien shan was tectonically quiescent for much of the cenozoic prior to uplift and exhumation in the late miocene the kyrgyz range was buried by sediments shed from highlands to the south and or east paired bedrock fission track and u th he ages from a sampling transect of 2 4 km relief demonstrate that rapid exhumation commenced at ca 11 ma initial thrusting in the hinterland was followed by evaporite accumulation 0 4 km m y which coincided with erosion of the pre 11 ma strata that mantled the kyrgyz range between 10 and 3 ma bedrockexhumation rates decreased to 0 3 km m y while sedimentation rates decelerated initially to 0 25 km m y before accelerating to 0 4 km m y at 4 5 ma detrital fission track results indicate that by 4 5 ma

kinematic model of active deformation in central asia the velocity field of present day deformation in central asia is modelled using a set of four rotating blocks siberia tarim tibet india on a spherical earth a best fit is inverted on the basis of estimated shortening rates across the main thrust zones himalayas tien shan and measured slip rates along the principal strike slip faults altyn tagh and karakorum separating those blocks the fit to the data implies that nearly all the present convergence between india and asia can be accounted for by slip partitioning on these four zones with as much as 50 absorbed by northeastwards extrusion of tibet this suggests that localised deformation governs the present mechanical behaviour of the central asian lithosphere

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

tracing dust sources and transport patterns using sr nd and pb isotopes continental dust transported through the atmosphere can be a tracer of atmospheric circulation and transport as well as being a source of information about climate in the dust s source area this information about the provenance of dust transported from desert areas and deposited elsewhere on the oceans and continents can be evaluated using several observational techniques satellite imagery has been used to this end in recent decades and air mass back trajectories have been calculated to trace dust deposits back to their source area another method consists of analysis of the concentration and composition of certain tracers in the dust itself and comparing them to soils and sediments from possible source areas this method has the advantage of being useable for paleo atmospheric circulation and paleo dust transport studies whereas satellite imagery and air mass back trajectories are restricted to relatively recent times we review here different kinds of isotopic tracers that have been used to trace dust provenance but special attention is focused on the use of sr nd and pb isotopes we evaluate their use in studies of both spatially as well as temporally varying continental dust source and transport

the influence of loess cave development upon landslides and geomorphologic evolution a case study from the northwest loess plateau china abstract loess caves landslides collapses bank erosion and soil erosion which are independently and interactively shaping the modern loess landscape are widely distributed across the chinese loess plateau the study area is located in a small watershed in huining county gansu province which is one of the areas with the strongest development of loess caves across the loess plateau this area is an ideal site for studying geological hazards and geomorphic evolution on the loess plateau seventeen landslides and 176 loess caves with a density of 887 units km2 were investigated with a uav unmanned aerial vehicle and mapped by gis geographic information system using high resolution uav images and topographic data we carried out an interpretation of loess caves bank erosion and landslides studied the spatial distribution and developmental patterns of loess caves landform morphology and the relationship between loess caves and landslides based on gis spatial analysis mathematical statistics and field surveys and analyzed the influence of loess microtopography on slope landforms finally six typical evolutionary models of soil erosion loess cave development landslide occurrence barrier dam formation are preliminarily proposed the primary slope stage early cave stage accelerated cave stage cave connecting stage landslide creeping stage and landslide dam forming stage this study is a useful exploration and an attempt to reveal the influence of loess cave development on slope stability and disaster chain effects

basin evolution within and adjacent to the tien shan range nw china two late palaeozoic collisions produced the ancestral tien shan range extension following the younger collision preceded a phase of thermal subsidence associated with fluvial and lacustrine sedimentation throughout the jurassic cretaceous and early tertiary this thermal subsidence was interrupted by renewed movement on palaeozoic reverse faults caused by the mesozoic collisions at the southern margin of asia the india asia collision in the early tertiary has produced widespread thrusting in the tien shan which in turn is responsible for the formation of active foreland basins at the southern and northern margins of the range and similar basins within the range itself this compression produced uplift and relief and consequent erosion gave rise to alluvial fans braidplains and ephemeral lakes in an extremely arid environment

pollen based quantitative reconstructions of holocene climate variability in nw romania abstract a modern analogue technique is applied to two high resolution pollen sequences from nw romania to provide the first quantitative evidence for winter summer and annual temperatures and for precipitation across the holocene in this region the pollen based climate reconstructions allow the identification of four main intervals i an early less stable period between 11 700 and 11 200 cal yr bp ii generally stable conditions between 11 200 and 8300 cal yr bp with winter and annual temperatures and precipitation higher than at present and summer temperatures about the same iii lower winter and annual temperatures and higher summer temperatures and precipitation between 8000 and 2400 cal yr bp iv warmer winter and annual temperatures and lower precipitation for the last 2400 years whereas summer temperatures became cooler at steregoiu and remained stable at preluca tiganului the pollen based climate reconstructions at the two sites show similar patterns in annual and winter temperatures and precipitation changes during the holocene but the trends appear to be less consistent for summer temperatures our pollen based reconstructions revealed several short term climatic oscillations during the holocene the strongest of which occur between 10 300 10 100 8300 8000 6800 6400 5100 4900 4000 3600 and 3200 3000 cal yr bp

multiproxy evidence of little ice age palaeoenvironmental changes in a peat bog from northern poland little ice age lia climatic deteriorations have been abundantly documented in various archives such as ice lake sediments and peat bog deposits palaeoecological analyses of peat samples have identified these climatic deteriorations using a range of techniques for example palynology plant macrofossils testate amoebae or carbon isotopic analyses the use of inorganic geochemistry and the reconstruction of dust fluxes has remained a challenge in tracing the nature of lia climatic changes although the idea of enhanced erosion conditions and storminess is commonly discussed the conditions for dust deposition in peatlands over europe during the lia are rarely favourable because the natural forest cover over europe was much more important than nowadays preventing dust deposition this intense forest canopy masks the deposition of dust in peatlands in northern poland near the baltic shore the slowin skie blota area was deforested around ad 1100 ie just before the lia and therefore constitutes a key area for the reconstruction of lia climatic change with the support of a well constrained chronology climatic fluctuations are recorded in an ombrotrophic bog using inorganic geochemistry plant macrofossils and carbon isotopic analyses the reconstruction of lia climatic changes is in good agreement with other records from poland and ne europe however a c 50 year discrepancy can be observed between various records this discrepancy is possibly due to progressive time dependent cooling gradient from north to south europe

quantification of three dimensional folding using fluvial terraces a case study from the mushi anticline northern margin of the chinese pamir fold deformation in three dimensions involves shortening uplift and lateral growth fluvial terraces represent strain markers that have been widely applied to constrain a fold s shortening and uplift for the lateral growth however the utility of fluvial terraces has been commonly ignored situated along northern margin of chinese pamir the mushi anticline preserves along its northern flank flights of passively deformed fluvial terraces that can be used to constrain three dimensional folding history especially lateral growth the mushi anticline is a geometrically simple fault tip fold with a total shortening of 740 110 m and rock uplift of 1300 m geologic and geomorphic mapping and dgps surveys reveal that terrace surfaces perpendicular to the fold s strike display increased rotation with age implying the fold grows by progressive limb rotation we use a pure shear fault tip fold model to estimate a uniform shortening rate of 1 5 1 3 0 5 mm a and a rock uplift rate of 2 3 2 1 0 8 mm a parallel to the fold s strike longitudinal profiles of terrace surfaces also display age dependent increases in slopes we present a new model to distinguish lateral growth mechanisms lateral lengthening and or rotation above a fixed tip this model indicates that eastward lengthening of the mushi anticline ceased by at least 134 ka and its lateral growth has been dominated by rotation our study confirms that terrace deformation along a fold s strike not only can constrain the lateral lengthening rate but can serve to quantify the magnitude and rate of lateral rotation attributes that are commonly difficult to define when relying on other geomorphic criteria

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

aeolian sediment in raised bog deposits halland sw sweden a new proxy record of holocene winter storminess variation in southern scandinavia cores of peat taken from two raised bogs in the near coastal part of halland sw sweden were examined for their content of wind transported clastic material the boarps mosse core has a length of 262 cm and covers the last 2850 years age model based on three radiocarbon dates while the hyltemossen core has a length of 347 cm and records the last 7000 years age model based on eight radiocarbon dates the peat contains aeolian quartz silt and sand from trace amount to more than 10 weight of the dry peat sample and the grain size composition of the minerogenic sediment indicates that the material is composed of both far travelled dust and local wind eroded silt and sand grains larger than 0 2mm are present in many intervals and probably record niveo aeolian transport in connection with severe snowstorms a systematic count of quartz grains between 0 2 0 35mm and larger than 0 35mm was carried out to determine variations in aeolian sand influx asi and winter wind climate with time the boarps m

fracture development in paleozoic shale of chongqing area south china part two numerical simulation of tectonic stress field and prediction of fractures distribution abstract a tectonics sedimentation evolution has been researched in southeast chongqing and the reasonable longmaxi shale highstand system tract hst and transgressive system tract tst geological model were built respectively based on the rock mechanical test and acoustic emission experiment which the samples are from field outcrop and the yuye 1 well the longmaxi shale two dimension tectonic stress field during the cenozoic was simulated by the finite element method and the distribution of fractures was predicted the research results show that the tectonic stress field and the distribution of fractures were controlled by lithology and structure as a result of cretaceous movement there are trough like folds wide spaced synclines battlement like folds similar spaces between synclines and anticlines and ejective folds wide spaced anticlines which are regularly distributed from southeast to northwest in the study area since the strain rate and other physical factors such as the viscosity are not taken into account and the stress intensity is the main factor that determines the tectonic strength therefore the stronger tectonic strength leads the higher stress intensity in the eastern and southeastern study area than in the northwest the fracture zones are mainly concentrated in the fold axis transition locations of faults and folds the regions where are adjacent to faults the fragile mineral contents such as siliceous rock carbonate rock and feldspar in the shelf facies shale from south of the study area are higher than in the bathyal facies and abyssal facies shale from center of the study area the shales characterized by low poisson s ratio and high elastic modulus from south of the study area are easily broken during cenozoic orogenic movement

late cenozoic tectonic evolution of the southern chinese tian shan structural sedimentological magnetostratigraphic and 40ar 39ar thermochronological investigations were conducted in the southern chinese tian shan on the basis of our own mapping and earlier investigations in the area the late cenozoic southern tian shan thrust belt may be divided into four segments based on their style of deformation from west to east they are 1 kashi aksu imbricate thrust system 2 the baicheng kuche fold and thrust system 3 the korla right slip transfer system and 4 the lop nor thrust system the westernmost kashi aksu system is characterized by the occurrence of evenly spaced 12 15 km imbricate thrusts the baicheng kuche and korla systems are expressed by a major north dipping thrust the kuche thrust that changes its strike eastward to become a nw striking oblique thrust ramp the korla transfer zone the lop nor system in the eastern most part of the southern chinese tian shan consists of widely spaced thrusts all involved with basement rocks geologic mapping and cross section construction suggest that at least 20 40 km of crustal shortening with a horizontal shortening strain of 20 30 has occurred in the southern chinese tian shan during the late cenozoic these estimates are minimum because of both conservative extrapolation of the thrust geometries and partial coverage of the thrust belt by the cross sections the timing of initial thrusting is best constrained in the kuche basin where crustal shortening may have occurred at 21 24 ma the time of a major facies transition between lacustrine and braided fluvial sequences constrained in general by biostratigraphy and in detail by magnetostratigraphy this estimate represents only a minimum age as development of thrusts in the southern chinese tian shan may have propagated southward toward the foreland thus the sedimentary record only represents the southernmost and therefore youngest phase of thrusting if our estimate of timing for the thrust initiation 21 24 ma is correct using the estimated magnitude of shortening 20 40 km and shortening strain 20 30 the averaged rates of late cenozoic horizontal slip and shortening strain are 1 1 9 mm yr 1 and 2 9 4 5 10 16 s 1 respectively our reconnaissance 40ar 39ar thermochronological analysis in conjunction with earlier published results of apatite fission track analysis by other workers in the chinese tian shan suggests that the magnitude of cenozoic denudation is no more than 10 km most likely less than 5 km we demonstrate via a simple airy isostasy model that when the thermal effect on changes in surface elevation is negligible determination of the spatial distribution and temporal variation of both horizontal shortening strain and denudation becomes a key to reconstructing the elevation history of the tian shan using this simple model the loosely constrained magnitude of crustal shortening strain and denudation in the southern chinese tian shan implies that it may have been elevated 1 0 2 0 km since the onset of cenozoic thrusting

high mountain region of the northern romanian carpathians responded sensitively to holocene climate and land use changes a multi proxy analysis a high altitude lake sediment sequence buh iescu mare 1918 m a s l in the subalpine zone of the rodna mountains was analysed through a multi proxy approach to determine the sensitivity of high mountain habitats to climate fire and land use changes the early holocene regional forests were dominated by pinus sylvestris and mugo and replaced by picea abies from 9800 cal yr bp after an extended hiatus in the profile c 9800 4200 cal yr bp probably because of the physical removal of sediments through avalanche or high flow events p abies abies alba and fagus sylvatica forests developed after 4200 cal yr bp the timberline and treeline reacted sensitively to past changes in climate and human impact the site was probably situated above the treeline throughout most of the investigated period however a treeline ecotone or krummholz zone may have sporadically reached the lake s elevation in the early holocene a decline in timberline and treeline elevation was noted during the last 1200 years and more evidently over the past 200 years with replacement by subalpine shrubs alnus viridis and alpine herbaceous communities because these vegetation changes were associated with an increased prevalence of pollen based anthropogenic indicators charcoal particles and abiotic indicators human induced fires and clearance and resultant erosion inputs to the lake are implied effects of current warming on the altitude range of trees are not yet visible probably because land use has more strongly contributed to changes in land cover than the climate fluctuations of the last millennium in the rodna mountains

mesozoic overthrust tectonics in south china whether south china was a platform or a para platform after the mid paleozoic deformation or whether the mountains of huanan south china form a mesozoic collision type orogen depends upon whether the ophiolite melange in the yangtze region is precambrian basement or was overthrust onto a foreland thrust belt during the mesozoic this paper presents evidence of tectonic windows under the melange and basement klippes above the melange in the yangtze region

flood events in transylvania during the medieval warm period and the little ice age we present here the first record of past flooding activity from the carpathian mountains eastern europe based on documentary evidence and sedimentary records along one of the main rivers draining

warm mediterranean mid holocene summers inferred from fossil midge assemblages reconstructions of holocene summer temperatures differ between models and vegetation based proxies a quantitative reconstruction for the mediterranean region based on fossil midge assemblages suggests warm summers in line with climate models

the δ18o and δ13c records in an aragonite stalagmite from furong cave chongqing china a 2000 year record of monsoonal climate abstract a 7 cm long aragonite stalagmite fr0510 1 from furong cave chongqing was dated by 210pb and 230th methods revealing a 2000 year record of climate history under the influence of the east asian monsoon the fr0510 1 record resembles dongge cave da record on 10 100 year scales but quite different from the wanxiang cave wx42b record indicating that while stalagmite 18o record represents local regional moisture change spatial variability of the monsoonal rainfall over eastern china must take into account during the past 2000 years climate in chongqing was relatively wet in the intervals of 50 bc ad 250 ad 1150 1450 and ad 1600 1950 and relatively dry during the periods of ad 250 1150 and ad 1450 1600 dry conditions were prevailing over the medieval warm period whereas wet climates were dominant during the most time of the little ice age in chongqing area

geochemical variations in peoria loess of western iowa indicate paleowinds of midcontinental north america during last glaciation peoria loess deposited in western iowa during the last glacial maximum lgm shows distinct geochemical and particle size variations as a function of both depth and distance east of the missouri river geochemical and particle size data indicate that peoria loess in western iowa probably had two sources the missouri river valley and a source that lay to the west of the missouri river both sources indicate that lgm paleowinds in western iowa had a strong westerly component similar to interpretations of previous workers a compilation of loess studies in iowa and elsewhere indicates that westerly winds were dominant during loess transport over much of the midcontinent south of the laurentide ice sheet which is not in agreement with paleowinds simulated by atmospheric general circulation models agcms agcms consistently generate a glacial anticyclone with easterly or northeasterly winds over the laurentide ice sheet and the area to the south of it loess deposition in the midcontinent during the lgm may be a function of infrequent northwesterly winds that were unrelated to the presence of the glacial anticyclone

quaternary climate change and the formation of river terraces across growing anticlines on the north flank of the tien shan china nested stream terraces warped upward over actively growing anticlines along the north flank of the tien shan in western china appear to record alternating phases of valley widening and incision differences of relative heights between remnants of four separate strath terraces along one river and between two such terraces along another reach 100 to 120 m over the crests of the anticlines we infer that this spacing is due to alternating stages of valley widening and rapid incision associated with climate changes with a periodicity of 100 kyr the crests of the anticlines appear to emerge from the aggrading flanks of the anticlines at an average rate of about 1 mm a the maximum heights of 25 and 35 10 m for the lowest terraces above their projected initial profiles imply ages of roughly 25 kyr and 35 kyr 10 kyr hence they suggest that flood plains which were abandoned to form the terraces developed adjacent to active stream beds during the last glacial period when climates were relatively

alluvial sequence in the north piedmont of the chinese tian shan over the past 550 kyr and its relationship to climate change abstract a new division of middle and late pleistocene alluvial sequence in the north piedmont of the chinese tian shan based on geomorphologic stratigraphic and chronologic criteria provides a framework for examining their relationship to climate change during glacial interglacial transitions over the past 550 kyr at least four major alluviation episodes occurred within the piedmont along the major river valleys in this region each episode of alluvial fan deposition morphologically correlates with a major river terrace these correlations create a regionally applicable framework for subdivision of the quaternary alluvial sequence in the study area where seven stepped river terraces are defined our new chronology of this fluvial sequence suggests that following intervals of aggradation three highest river terraces and equivalent alluvial fans were abandoned at 530 ka 300 ka and 10 ka respectively paleosols at the base of the loess sequences that directly overlie the older terraces and fans suggest that episodes of aggradation occurred late in the glacial cycles the subsequent incision that caused abandonment stabilization of these terraces and fans occurred near to glacial interglacial transitions a relatively high degree of synchrony in major river incision events across the piedmont despite disruption by several discrete structure zones with asychronous tectonic activities supports the dominant control exerted by climatic conditions on alluvial deposition and terrace creation during the quaternary across the north piedmont of the chinese tian shan

holocene hydrological changes inferred from alluvial stream entrenchment in north tian shan northwestern china abstract we analyze the possible contribution of climate change or tectonics on fluvial incision from the study of a case example along the northern flank of tian shan the rivers that exit the high range fed large alluvial fans by the end of the last glacial period they have since deeply entrenched the piedmont by as much as 300 m we have surveyed several terraces that were cut and abandoned during river entrenchment providing information on intermediate positions of the riverbed during downcutting they suggest a gradual decline in river slope during a major phase of incision throughout the holocene tectonic uplift affects only a zone about 5 km wide corresponding to a growing anticline and is shown to account for about 10 of total incision incision was therefore most probably driven by climate change from observed fluvial incision we estimate the water discharge in excess of that needed to carry the sediments supplied by hillslope erosion in the headwaters we used a model based on a transpor

the contemporary physical and chemical flux of aeolian dust a synthesis of direct measurements of dust deposition abstract the deposition of aeolian or windblown dust is widely recognized as an important physical and chemical flux to ecosystems dust deposition adds exogenous mineral and organic material to terrestrial surfaces and can be important for the biogeochemical cycling of nutrients there have been many studies that characterize the physical and chemical composition of dust however few studies have synthesized these observations in order to examine patterns geochemical fluxes we have compiled observations of dust deposition rates particle size distributions psd mineralogy and bulk elemental and organic chemistry the rates of dust deposition observed across the globe vary from almost 0 to greater than 450 g m 2 yr 1 sites receiving dust deposition can be partitioned into broad categories based on there distance from dust source regions when compared to global dust models our results suggest some models may underestimate dust deposition rates at the regional and local scales the distance from the source region that dust is deposited also influences the particle size distributions mineralogy and chemical composition of dust however more consistent dust sampling and geochemical analyses are needed to better constrain these spatial patterns on average the concentrations of most major elements si al fe mg ca k in aeolian dust tend to be similar 20 to the composition of the upper continental crust ucc but there is substantial variability from sample to sample in contrast some elements tend to be depleted na or enriched ti in dust likely as a result of soil weathering processes prior to dust emissions trace elements especially heavy metals are consistently enriched in dust relative to the ucc ecologically important nutrients such as n and p are also present in dust deposition the geochemical flux attributable to dust deposition can be substantial in ecosystems located proximal to dust source regions we calculate estimates of elemental flux rates based on the average chemical composition of aeolian dust and varying rates of deposition these estimated flux rates are useful as a rough gauge of the degree to which dust deposition may influence biogeochemical cycling in terrestrial ecosystems and should be utilized to better constrain deposition estimates of global dust models

holocene vegetation history in the upper forest belt of the eastern romanian carpathians abstract pollen analysis supported by nine ams 14 c dates from the poiana tiol peat sequence 1540 m in the rodnei mountains eastern romanian carpathians romania is used to reconstruct the holocene vegetation history in this mountain region the results are then compared with other sequences from romania and eastern europe in order to better understand the past dynamics of the main forest constituents the vegetation record at poiana tiol starts at ca 11 000 cal yr bp with the occurrence of rather closed woodlands composed of betula pinus picea abies alnus a viridis and ulmus picea abies was the dominant tree species for almost the entire period however during the last 3000 years p abies forests were largely replaced by pinus in the area temperate tree taxa fraxinus quercus acer tilia and corylus avellana were also common but likely at lower elevation c avellana expanded around 10 300 cal yr bp and reached maximum values after 9000 cal yr bp pollen of carpinus betulus and fagus sylvatica was already recorded around 7000 cal yr bp however the spread of c betulus occurred at ca 6000 cal yr bp with maximum values between 4800 cal yr bp and 3000 cal yr bp while f sylvatica spread from ca 3200 cal yr bp and attained maximum values between 2000 and 200 cal yr bp the first indications of human activities appeared around 3200 cal yr bp and intensified within the last 200 years comparison with other sequences from romania and surrounding countries reveals both similarity and great differences related to the location of glacial refugia climate change and human impact

carbon isotope composition as indicator for climatic changes during the middle and late holocene in a peat bog from maramures mountains romania the main goal of this study was to use stable carbon isotopic composition of bulk peat sampled in t ul mare bard u peat bog maramures mountains as a tool to provide paleoclimatic information over the middle and late holocene in this region a peat core of 3 60 m was sampled for 13c analysis and bulk peat samples were analyzed by isotope ratio mass spectrometry irms method 13c values reveal a maximum variation of 4 69 along a 3 6 m long peat core we examined the vertical variation of 13c bulk peat and concluded that several factors could contribute to up core trends of 13c four intervals of climatic variability could be related with variations of 13c values between 6800 cal yr bp and present two wet periods around 2800 and 545 cal yr bp and two dry periods 6760 and 1430 cal yr bp we concluded that variability in the 13c of bulk peat profile could be influenced most heavily by the water availability which in turn is related to the amount of precipitation at the time four intervals

disentangling dust and sand deposition using a peat record in ce europe northern romania a multiproxy approach abstract aeolian sediments play an important role in the global climatic system and occur in the atmosphere due to soil and bedrock erosion here we applied three different methods geochemical xrf manual and laser based particle size analysis to an ombrotrophic peat profile in the carpathian mountains to determine changes in aeolian deposition and wind storm activity over the last 7800 years the results show the following changes in aeolian fluxes dust and sand over time 7800 4150 cal yr bp generally low dust fluxes with a periodic intensification of sand fluxes 4150 2300 cal yr bp intense deposition of both dust and sand 2300 150 cal yr bp fluctuating dust and sand fluxes the last 200 years the highest amplitude of both sand and dust fluxes this study found that patterns in aeolian fluxes were influenced by a combination of climate and human impact but with anthropogenic drivers such as disturbance by fire becoming more important in recent times we also found a good agreement with other studies of dust fluxes for the earlier part of this record but an increasing divergence over the last 3500 years in terms of a methodological approach we suggest that the three approaches each have both advantages and disadvantages though overall laser based particle size dust and sand reconstruction appears to best capture the most complex changes in both aeolian deposition rates and sources

new evidence for the incision history of the liuchong river southwest china from cosmogenic 26al 10be burial ages in cave sediments cosmogenic nuclides be 10 and al 26 have been analyzed for sediments from the multilevel riverside caves along the liuchong river at the southeastern margin of the tibetan plateau the liuchong river is the northern origin of wujiang river which passes through the northwestern guizhou plateau and cuts down hundreds of meters into the bedrock leaving behind an abundance of multilevel caves the measured al 26 be 10 ratios produced the apparent burial ages in range of 0 49 2 85 ma taking into account of geomorphic and geological backgrounds the dashi cave located at the highest level along the liuchong river system formed around 0 75 ma ago which probably suggests the initial formation age of the modern wujiang river the resulted incision rate of similar to 480 m ma in guizhou in the last 0 75 ma is slightly higher than those in adjacent areas this feature implies an intensive downcutting history of the liuchong river during the quaternary which might be primarily caused by the uplift of tibetan plateau cut through of the three gorges and soluble carbonate bedrock c 2013 elsevier ltd all rights reserved

a peat bog record of natural pre anthropogenic enrichments of trace elements in atmospheric aerosols since 12 370 14 c yr bp and their variation with holocene climate change abstract a peat bog in the jura mountains switzerland provides a continuous record of peat accumulation since 12 370 14 c yr bp periods of enhanced soil dust deposition 10 590 14 c yr bp 8230 14 c yr bp and after 5320 14 c yr bp are characterized by strongly elevated ti sc and zr sc ratios which imply an increase in the abundance both relative and absolute of heavy minerals such as ilmenite and zircon with respect to trace elements such as cu zn as cd sb and au the m sc ratios are at their lowest and often approach crustal values during periods of enhanced soil dust deposition the lowest rates of atmospheric deposition of soil dust date from 8030 to 5320 14 c yr bp corresponding to the holocene climate optimum but here many trace elements exhibit their greatest natural enrichments the average enrichment factor calculated using sc as the reference element and normalizing to crustal abundance was zn 4 1 1 4 sb 4 8 1 4 cu 8 8 3 3 as 14 9 3 2 au 53 9 25 1 and cd 357 4 53 8 these enrichments cannot be explained by chemical diagenesis within the deeper sections of the peat profile during or subsequent to peat formation but rather reflect the chemical composition of airborne material supplied to the surface layers of the bog at the time of deposition the enrichments of trace metals in ancient peats relative to crustal abundance most likely reflects the natural enrichment of these elements in the fine fraction of soils during rock weathering periods of enhanced soil dust deposition such as the younger dryas cold climate phase 10 590 14 c yr bp are characterized by reduced vegetation cover greater exposed soil surface and higher wind strengths these conditions promote the transport of locally derived soil materials of greater particle size lower concentration of trace metals and m sc ratios approaching crustal values during the holocene climate optimum vegetation cover was extensive and with lower wind strengths and a reduction in erodible soil materials long range transport of soil dust became relatively more important to the soil dust inventory of the bog soil dust particles in this size class are characterized by strong enrichments of a wide range of trace elements at the end of the holocene optimum dust fluxes increased once again due mainly to soil erosion resulting from the combined effects of human activities tillage and the climatic deterioration at the beginning of the neoglaciation period this promoted the supply of local more coarse soil particles with m sc ratios approaching those of crustal rocks while biological cycling and volcanic emissions probably also contributed to the atmospheric supply of many of these elements in the pre anthropogenic past these contributions appear to be less important than the chemical weathering physical fractionation and atmospheric transport of soil dust particles

origin and tectonic significance of a mesozoic multi layer over thrust system within the yangtze block south china abstract in the yangtze block south china a well developed mesozoic thrust system extends through the xuefeng and wuling mountains in the southeast to the sichuan basin in the northwest the system comprises both thin and thick skinned thrust units separated by a boundary detachment fault the dayin fault to the northwest the thin skinned belt is characterized by either chevron anticlines and box synclines to the northwest or chevron synclines to the southeast the former structural style displays narrow exposures for the cores of anticlines and wider exposures for the cores of synclines thrust detachments occur along silurian fs and lower cambrian fc strata and are dominantly associated with the anticlines to the southeast this style of deformation passes gradually into one characterized by chevron synclines with associated principal detachment faults along silurian fs cambrian fc and lower sinian fz strata there are however numerous secondary back thrusts therefore the thin skinned belt is like the valley and ridge province of the north american applachian mountains the thick skinned belt structurally overlies the thin skinned belt and is characterized by a number of klippen including the xuefeng and wuling nappes it is thus comparable to the blue ridge province of appalachia the structural pattern of this thrust system in south china can be explained by a model involving detachment faulting along various stratigraphic layers at different stages of its evolution the system was developed through a northwest stepwise progression of deformation with the earliest delamination along lower sinian strata fz analyses of balanced geological cross sections yield about 18 1 21 total 88 km shortening for the thin skinned unit and at least this amount of shortening for the thick skinned unit the compressional deformation from southeast to northwest during late jurassic to cretaceous time occurred after the westward progressive collision of the yangtze block with the north china block and suggests that the orogenic event was intracontinental in nature

storminess variation during the last 6500 years as reconstructed from an ombrotrophic peat bog in halland southwest sweden cores taken from an ombrotrophic peat bog in the coastal zone of halland southwest sweden were examined for wind transported mineral grains pollen and humidity indicators the core covers the period from 6500 cal yr bp to present ombrotrophic conditions existed from ca 4200 cal yr bp onwards bog surface wetness fluctuated strongly until ca 3700 cal yr bp with an apparent dominance of dry summer conditions from 4800 4500 cal yr bp local wet shifts occurred around 4300 2800 2400 and 1500 cal yr bp whereas the most recent 600 years of the record show increasingly dry conditions mineral grain content interpreted as aeolian sand influx asi was used as a proxy for winter storm frequency and intensity until ca 1500 cal yr bp after which increasing human impact as reconstructed by pollen analysis became a second important potential cause for increased sand drift strongly increased storminess occurred at 4800 4200 2800 2200 1500 1100 and 400 50 cal yr bp indicating a dominance of cold and stormy winters during these periods many of these storm periods apparently coincide with storm events in other sites in southwestern scandinavia suggesting that our asi record reflects a regional scale climatic signal furthermore these stormy periods correlate to well known cold phases in the north atlantic region suggesting a link to large scale fluctuations in atmospheric circulation patterns less

looping caves versus water table caves the role of base level changes and recharge variations in cave development abstract the vertical organisation of karst conduit networks has been the focus of speleogenetic studies for more than a century the four state model of ford and ewers 1978 which still is considered as the most general relates the geometry of caves to the frequency of permeable fissures the model suggests that the water table caves are common in areas with high fissure frequency which is often the case in natural settings however in alpine karst systems water table caves are more the exception than the rule alpine speleogenesis is influenced by high uplift valley incision rates and irregular recharge to study the potential role of these processes for speleogenesis in the dimensions of length and depth we apply a simple mathematical model based on coupling of flow dissolution and transport we assume a master conduit draining the water to the spring at a base level incision of the valley triggers evolution of deeper flow pathways which are initially in a proto conduit state the master conduit evolves into a canyon following the valley incision while the deep pathways evolve towards maturity and tend to capture the water from the master conduits two outcomes are possible a deep pathways evolve fast enough to capture all the recharge leaving the master conduit dry or b the canyon reaches the level of deep pathways before these evolve to maturity we introduce the loop to canyon ratio lcr which predicts which of the two outcomes is more likely to occur in certain settings our model is extended to account for transient flow conditions in the case of an undulating master conduit floodwater is stored in troughs after the flood retreat this water seeps through sub vertical fractures soutirages connecting the master conduit with the deep pathways therefore the loops evolve also during the dry season and the lcr is considerably increased although the model is based on several approximations it leads to some important conclusions for vertical organisation of karst conduit networks and stresses the importance of base level changes and transient recharge conditions it therefore gives an explanation of speleogenesis that relies much more on the dynamic nature of water flow than on the static fracture density

building the northern tien shan integrated thermal structural and topographic constraints abstract paired apatite fission track and u th he dates provide the first late cenozoic cooling ages for the northern tien shan these data clearly argue for pulsed deformation since the late miocene with early 10 11 ma and late 0 3 ma intervals of rapid exhumation separated by an extended interval of much slower rates by integrating these bedrock cooling rates with shortening estimates derived from a balanced section detrital cooling ages and geomorphological estimates of conditions before deformation we reconstruct a four stage history of range growth and exhumation following 100 m yr of tectonic quiescence abruptly accelerated rock uplift exhumation and cooling in the kyrgyz range commenced at 11 ma with rates exceeding 1 km m yr during the subsequent 7 m yr deformation and cooling rates decreased three to sixfold before accelerating by comparable amounts during the past 3 m yr since mid miocene times the surface elevation of the kyrgyz range has increased 2 km consistent with

fracture development in paleozoic shale of chongqing area south china part one fracture characteristics and comparative analysis of main controlling factors abstract natural macro and micro fractures in the longmaxi shale lower silurian from yuye 1 well and the niutitang shale lower cambrian from yuke 1 well are characterized regional geological structural evolution and shale geochemistry including toc and mineral composition etc are analyzed the controlling factors of natural fractures in palaeozoic shale in the southeast of chongqing have been confirmed which have been analyzed qualitatively or semi quantitatively the results show that fractures are abundant in both the longmaxi shale and niutitang shale due to the multiphase strong tectonic movement in the southeast of chongqing therefore tectonic factors are the principal factors that control fracture development in the paleozoic shale of this region followed by the mineral composition of the shale vertically the mineral composition of shale in yuke 1 well has a high dispersion degree and a strong heterogeneity the dispersion coefficients of quartz and dolomite were 0 48 and 1 respectively therefore the development and distribution of fractures are controlled by quartz and dolomite content in the niutitang shale moreover the quartz content shows positive correlation with the fractures quantity and fractures are most abundant where dolomite content up to 64 7 while the mineral composition of shale in yuye 1 well has a low dispersion degree and a strong homogeneity in a vertical position the dispersion coefficients of quartz and plagioclase were 0 15 and 0 26 respectively which shows unconspicuous control effect for fractures therefore the development and distribution of fractures are mainly controlled by the toc content moreover the toc content shows positive correlation with the fractures quantity fractures are sealed by calcite quartz and pyrite although sealed fractures do not contribute to the permeability of the reservoir they are important planes of weakness that tend to be reactivated by hydraulically induced fractures sem images show that intergranular pore is connected by microfractures thereby the validity of porosity has been improved the mixed network of microfractures and micropore provide enhanced permeability or storage capacity for the reservoir

dust sources and deposition during the last glacial maximum and current climate a comparison of model results with paleodata from ice cores and marine sediments mineral dust aerosols in the atmosphere have the potential to affect the global climate by influencing the radiative balance of the atmosphere and the supply of micronutrients to the ocean ice and marine sediment cores indicate that dust deposition from the atmosphere was at some locations 2 20 times greater during glacial periods raising the possibility that mineral aerosols might have contributed to climate change on glacial interglacial time scales to address this question we have used linked terrestrial biosphere dust source and atmospheric transport models to simulate the dust cycle in the atmosphere for current and last glacial maximum lgm climates we obtain a 2 5 fold higher dust loading in the entire atmosphere and a twenty fold higher loading in high latitudes in lgm relative to present comparisons to a compilation of atmospheric dust deposition flux estimates for lgm and present in marine sediment and ice cores show that the simulated flux ratios are broadly in agreement with observations differences suggest where further improvements in the simple dust model could be made the simulated increase in high latitude dustiness depends on the expansion of unvegetated areas especially in the high latitudes and in central asia caused by a combination of increased aridity and low atmospheric co2 the existence of these dust source areas at the lgm is supported by pollen data and loess distribution in the northern continents these results point to a role for vegetation feedbacks including climate effects and physiological effects of low co2 in modulating the atmospheric distribution of dust

lake belau and its catchment northern germany a key archive of environmental history in northern central europe since the onset of agriculture the environmental history since the onset of agriculture was reconstructed from sediments and soils in the catchment area of lake belau schleswig holstein northern germany the established chron

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

sand mass accumulation rate as a proxy for wind regimes in the sw barents sea during the past 3 ka aeolian sand mass accumulation rates were determined in a coastal mire complex on the north norwegian island soroya this measure of aeolian activity is used as a proxy for past storm intensity in the sw barents sea region at least until the seventeenth century when human activities began to obscure the natural signal aeolian erosion started to increase in the sixth century and consistently high values are recorded from the eleventh century onwards periods of relatively increased aeolian activity can be seen 1200 800 bc 550 150 bc ad 500 850 ad 1000 1400 and ad 1700 2000 increased aeolian activity here indicates a higher frequency of east tracking storm systems at 70 n potential causes for such conditions are increased advection of atlantic water and intensification and or northward displacement of the main winter storm tracks normally associated with moist westerlies and positive nao conditions other noteworthy climatic events are 1 a short but severe wet spell is recorded in the late tenth

structure and origin of holocene cold events abstract the present interglacial the holocene spans the period of the last 11 700 years it has sustained the growth and development of modern society the millennial scale decreasing solar insolation in the northern hemisphere summer lead to northern hemisphere cooling a southern shift of the intertropical convergence zone itcz and a weakening of the northern hemisphere summer monsoon systems on the multidecadal to multicentury scale periods of more stable and warmer climate were interrupted by several cold relapses at least in the northern hemisphere extra tropical area based on carefully selected 10 000 year long time series of temperature and humidity precipitation as well as reconstructions of glacier advances the spatiotemporal pattern of six cold relapses during the last 10 000 years was analysed and presented in form of a holocene climate atlas hoclat see http www oeschger unibe ch research projects holocene atlas a clear cyclicity was not found and the spatiotemporal variability of temperature and humidity precipitation during the six specific cold events 8200 6300 4700 2700 1550 and 550 years bp was very high different dynamical processes such as meltwater flux into the north atlantic low solar activity explosive volcanic eruptions and fluctuations of the thermohaline circulation likely played a major role in addition internal dynamics in the north atlantic and pacific area including their complex interaction were likely involved

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

the role of fire in landscape dynamics an example of two sediment records from the rodna mountains northern romanian carpathians fire is an important disturbance agent worldwide and one of the major causes of geomorphological change dependent on its characteristics size duration temperature fire induces changes in soil stability modifying infiltration and promoting soil erosion here we employ a suite of physical mineral magnetic loss on ignition geochemical xrf derived elemental data biological macro charcoal pollen proxies and dating measurements ams 14c 210pb and 137cs to examine the relationship between fire activity sedimentary characteristics and geomorphological change over the holocene our results highlight that fire events imprint a magnetic signature characterised by secondary ferrimagnetic assemblage particularly very fine superparamagnetic sp magnetite and maghemite in lake buh iescumare the early holocene is characterised bymoderate fire activity and coarser sediment particle size indicating a relatively unstable catchment affected by burning events which activated erosional processes subsequently the late holocene 4 000 0 cal yr bp is marked by intermittently variable fire activity with sporadic increases between 3 400 and 3 200 cal yr bp and around 2 000 cal yr bp when burning was strong enough to lead to the magnetic enrichment of topsoil and detrital inputs to the lake in our high resolution record lake tiol the interval 2 500 700 cal yr bp and also the last 100 years are characterised by intense burning that coincides with sustained surface soil erosion and magnetic enrichment the fire erosion landscape relationship varies over time being highly dependent on fire behaviour fire temporal and spatial distribution and landscape features slope soil type vegetation cover

syntectonic growth strata and implications for late cenozoic tectonic uplift in the northern tian shan china abstract propagation of faults and folds in the foreland basins of tian shan is an important process accommodating cenozoic crustal shortening and mountain building but little is known about the accurate time of the cenozoic tectonic deformation based on growth strata and age determination we show that syntectonic growth strata began to develop in the middle part of tian shan since 6 ma ago geometry analysis indicates that formation of the growth strata is associated with progressive fold limb rotation formation of the growth strata is contemporaneous with the tectonic deformation in the thrusting and folding zones together with the remarkable increase of sedimentation rate as well as the accumulation of coarse molasse deposits we conclude that the late cenozoic crustal shortening and mountain building in the region initiated since about 6 ma and lasted to the early pleistocene as a consequence of intracontinental deformation within the india eurasia convergent system

constraints on alpine speleogenesis from cave morphology a case study from the eastern totes gebirge northern calcareous alps austria abstract the totes gebirge is the largest karst massif in the northern calcareous alps nca this paper focuses on the eastern part where two major multiphase alpine cave systems burgunderschacht cave system and dof sonnenleiter cave system are described with respect to morphology hydrology and sediments the caves consist of upper miocene galleries of epi phreatic genesis and younger vadose canyon shaft systems morphometrical analyses were used to determine the relevance of 1 cave levels horizontal accumulations of galleries 2 slightly inclined palaeo water tables of speleogenetic phases 3 initial fissures and 4 inception horizons on the development of the cave systems epi phreatic cave conduits developed preferentially along vertical faults and along only a restricted number of bedding planes which conforms to the inception horizon hypothesis for at least one of the systems a development under epiphreatic conditions is certain and a hydrological behaviour in the filling overflow manner is likely observations in further major cave systems in the totes gebirge identify palaeo water tables of speleogenetic phases that show inclinations of 1 5 1 analyses of cave levels reveal distinct peaks for each cave but it is hardly possible to correlate these elevation levels between caves of different parts of the karst massif therefore we conclude that cave levels strictly horizontal indicate speleogenetic phases or palaeo water tables respectively but they cannot be correlated with palaeo base levels or on regional scale an exact correlation between cave development and palaeo base levels at the surface is only possible with inclined palaeo water tables of speleogenetic phases for the totes gebirge the inclination directions of the speleogenetic phases imply that palaeo drainage was radial and recharge was autogenic which is in contrast to observations from other plateaus in the nca differences in fracture properties seem to be the reason for the development of divergent types according to the four state model a simplified model for cave genesis and surface development in this area since the upper miocene is presented

balanced cross section construction from seismic sections in areas of extensional tectonics abstract the application of the technique of balanced section construction initially developed for areas of compressional folding and faulting is reviewed with reference to extensional tectonics a number of examples are discussed where these techniques have been successfully applied in the north sea the interpretation of geoseismic sections is considered to be greatly assisted by careful application of geometrical balance and a consideration of strain even in areas of low crustal extensions the nature of seismic sections however places limitations on the validity of balancing which must be borne in mind with such interpretations and wherever possible the balancing of a geoseismic section should be confirmed by complete depth conversion the rapid testing of the integrity of the geoseismic section by attempting to balance the section at the interpretational phase can eliminate many problems as well as allowing the fullest use to be made of the geophysical information

late glacial to holocene aeolian deposition in northeastern europe the timing of sedimentation at the iisaku site ne estonia abstract the late glacial and holocene aeolian inland dune complex at iisaku ne estonia has been investigated using an accurate and detailed compilation of the sedimentary properties and chronological framework the quartz grains forming the dunes are very variable reflecting aeolian weathering and periglacial conditions both prior and after deposition although the morphological forms and the sedimentary record point to a dune like environment the transport record reflects either a short transport time or and distance and a contribution from neighbouring sedimentary environments dune development in the area was strongly controlled by the formation of the baltic ice lake bil in front of the retreating glacier luminescence ages from the aeolian complex suggest continuous deposition between 13 3 1 2 to 10 5 0 7 ka however the chronology of sand deposition also suggests phases in this aeolian activity 1 at 13 3 1 2 ka and onwards possibly correlated with the existence of an island separating the bil and peipsi lake 2 between 12 7 0 8 12 5 0 8 ka representing the younger dryas cold reversal 3 between 11 5 0 7 10 9 0 8 ka indicating that aeolian deposition continued over the younger dryas holocene boundary and 4 early holocene sand drift at 10 5 0 7 ka

potentials and problems of building detailed dust records using peat archives an example from store mosse the great bog sweden mineral dust deposition is a process often overlooked in northern mid latitudes despite its potential effects on ecosystems these areas are often peat rich providing ample material for the reconstruction of past changes in atmospheric deposition the highly organic up to 99 in some cases matrix of atmospherically fed mires however makes studying the actual dust particles grain size mineralogy challenging here we explore some of the potentials and problems of using geochemical data from conservative lithogenic elements al ga rb sc y zr th ti and ree to build detailed dust records by using an example from the 8900 yr peat sequence from store mosse the great bog which is the largest mire complex in the boreo nemoral region of southern sweden the four dust events recorded at this site were elementally distinct suggesting different dominant mineral hosts the oldest and longest event 6385 5300 cal yr bp sees a clear signal of clay input but with increasing contributions of mica feldspar and middle ree rich phosphate minerals over time these clays are likely transported from a long distance source 100 km while dust deposition was reduced during the second event 5300 4370 cal yr bp this is the most distinct in terms of its source character with eu eu ucc revealing the input of plagioclase feldspar from a local source possibly active during this stormier period the third 2380 2200 cal yr bp and fourth 1275 1080 cal yr bp events are much shorter in duration and the presence of clays and heavy minerals is inferred elemental mass accumulation rates reflect these changes in mineralogy where the relative importance of the four dust events varies by element the broad changes in major mineral hosts grain size source location and approximated net dust deposition rates observed in the earlier dust events of longer duration agree well with paleoclimatic changes observed in northern europe the two most recent dust events are much shorter in duration which in combination with evidence of their local and regional character may explain why they have not been seen elsewhere

quantification of growth and lateral propagation of the kashi anticline southwest chinese tian shan received 11 february 2006 revised 16 january 2007 accepted 2 february 2007 published 28 march 2007 1 the kashi anticline is a north vergent asymmetric doubly plunging detachment fold located in the sw tian shan foreland we combine structural magnetostratigraphic and topographic data to define the fold s lateral propagation surface uplift and concomitant exhumation two new magnetostratigraphic sections indicate that the fold began growing at 1 4 ma and by 1 07 ma deformation had propagated eastward 13 km at an average rate of 40 km myr subsequently propagation rates increased at least twofold until the fold reached 60 km in length by 0 8 0 3 ma since then eastward fold propagation slowed to 15 km myr and the eastern 15 25 of the fold remains buried in the rapidly aggrading foreland the structure and topography of the emergent fold support interpretations of fold growth in three stages initial symmetric lateral growth both east and west to a total length of 30 km followed by first rapid and then slower eastward lengthening to 72 10 km total length shortening rates as high as 1 9 0 2 0 3 mm yr characterize the western part of the fold but decrease toward the east significant dissection of the emergent fold does not occur until topographic relief is sufficient 200 m to permit stripping of protective conglomerates from across the fold s upper surface as differential rock uplift continues following breaching of the conglomerate 75 of the rock raised above local base level is subsequently eroded at rates as high as 2 4 km myr despite extensive erosion the modern fold topography mimics spatial patterns of both long term shortening and variations in rock uplift

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

late quaternary faulting on the manas and hutubi reverse faults in the northern foreland basin of tian shan china abstract the tian shan range lies in the actively deforming part of the india asia collision zone in the northern foreland basin of tian shan the strata were intensively deformed by cenozoic folding and faulting slip rate studies along these faults are important for understanding the dynamics of crustal deformation and evaluating the seismic hazards in the region two reverse faults the manas and hutubi faults in the northern foreland basin were investigated due to past faulting events along these faults the terrace treads along the manas river were ruptured forming fault scarps several meters in height loess deposits were trapped and preserved at the surface ruptures along these scarps the thickness of the trapped loess is dependent on the size of the ruptures the minimum and maximum ages of these scarps are constrained by dating the loess preserved at the surface ruptures and the terrace treads respectively using the quartz optically stimulated luminescence osl dating technique our dating results suggest that the loess trapped at the ruptures was deposited from the early to mid holocene at the hutubi fault and from the mid to late holocene at the manas fault the vertical displacements of the faults were evaluated by measuring the topographic profiles across the investigated fault scarps using the differential global position system dgps our results suggest that during the late quaternary in the studied region the vertical slip rates of the manas fault were between 0 74 mm yr and 1 6 mm yr while the hutubi fault had a much lower vertical slip rate between 0 34 mm yr and 0 40 mm yr the tectonic implications of our results are discussed

a multi proxy analysis of hydroclimate trends in an ombrotrophic bog over the last millennium in the eastern carpathians of romania abstract we describe an ombrotrophic bog profile from tinovul mohos eastern carpathians romania to quantitatively reconstruct the hydroclimate and the palaeoecological evolution over the past 1000 years findings are based on high resolution analyses of testate amoebae plant macrofossils pollen micro and macrocharcoal 13c stable carbon isotopes organic matter content and bulk density supported by ams radiocarbon dating we identify five major hydroclimatic intervals between ad 1050 and 1300 a wet period occurred associated with a time of reduced human population between ad 1300 and 1600 wet conditions continued to prevail but with tendency towards drier mire settings the third period from ad 1600 1680 revealed two abrupt disturbances in the local hydrology strong dry wet shifts the fourth period from ad 1680 1950 showed intermediate moist conditions with an increased humidity after ad 1950 mire conditions became dry and there was an intensification in disturbances activity forest clearance fire and peatland drainage our multi proxy reconstruction represents one of the few studies of the hydroclimate and palaeoecological evolution of the last millennium in the central eastern europe findings show good agreement with other hydroclimate reconstructions from this region but not with records from north western europe more high resolution multi proxy studies are needed to improve our understanding of the feedback mechanisms in peatlands and the factors behind these changes

geological constraints on cave development in the plateau gorge karst of south china wulong chongqing abstract the houping tiankeng cluster is a part of the south china karst unesco world natural heritage site within the distinctive wulong plateau gorge karst 200 km of cave passages have been documented to date this paper focuses on detailed tectonic and morphological research on the luo shui kong cave enriched with u series dating of speleothems and complemented by morphometric analysis of the san wang dong and er wang dong caves all of these caves exhibit three regional levels of cave development 1 1040 1020 m a s l 2 900 840 m a s l and 3 740 660 m a s l the houping tiankeng area is a carbonate rock sequence several hundred meters thick overlain by the less soluble lower ordovician strata limiting recharge points to faults exposing underlying easily soluble formations this leads to the domination of concentrated high volume inflow and thus results in caves of large volume in the plateau gorge karst shafts connecting the surface with cave passages located underneath formed along faults changing the hydrogeological pattern through karst water capture and remodeling of existing conduits albeit mainly by increasing their overall dimensions rather than by deepening them the most favorable structures for cave level development are two sets of joints conjugated with gently inclined bedding since these joints are characterized by a small vertical extent downward development is limited hence most of the passages are wide but not deep canyons and typical of a water table cave pattern places where the fault plane is eroded from the surface and where at the same time an underneath cave chamber ceiling expands upwards are particularly predisposed to the formation of a tiankeng

late pleistocene shortening rate on the northern margin of the yanqi basin southeastern tian shan nw china abstract how strain is distributed and partitioned on individual faults and folds on the margins of intermontane basins remains poorly understood the haermodun ha anticline located along the northern margin of the intermontane yanqi basin on the southeastern flank of the tian shan preserves flights of passively deformed alluvial terraces these terraces cross the active anticline and can be used to constrain local crustal shortening and uplift rates geologic and geomorphic mapping in conjunction with high resolution dgps topographic surveys reveal that the terrace surfaces are perpendicular to the fold s strike and display increased rotation with age implying that the anticline has grown by progressive limb rotation combined with the open sinusoidal curve model and excess area method we calculated uplift and shortening values for each terrace since abandonment using the published exposure ages of each terrace we found the vertical uplift rate gradually decreased from 0 43 to 0 11 mm a whereas the shortening rate remained constant at 0 3 mm a since the anticline began to grow a fresh fault scarp 0 4 0 1 m high is visible along the southern portion of the ha anticline and is interpreted to be the most recent evidence of seismic activity using an estimated rupture area and the length of the fresh offset created by this earthquake we estimate that the main thrust underlying the ha anticline has generated moderate m

dirtmap the geological record of dust atmospheric dust is an important feedback in the climate system potentially affecting the radiative balance and chemical composition of the atmosphere and providing nutrients to terrestrial and marine ecosystems yet the potential impact of dust on the climate system both in the anthropogenically disturbed future and the naturally varying past remains to be quantified the geologic record of dust provides the opportunity to test earth system models designed to simulate dust records of dust can be obtained from ice cores marine sediments and terrestrial loess deposits although rarely unequivocal these records document a variety of processes source transport and deposition in the dust cycle stored in each archive as changes in clay mineralogy isotopes grain size and concentration of terrigenous materials although the extraction of information from each type of archive is slightly different the basic controls on these dust indicators are the same changes in the dust flux and particle size might be controlled by a combination of a source area extent b dust emission efficiency wind speed and atmospheric transport c atmospheric residence time of dust and or d relative contributions of dry settling and rainout of dust similarly changes in mineralogy reflect a source area mineralogy and weathering and b shifts in atmospheric transport the combination of these geological data with process based forward modelling schemes in global earth system models provides an excellent means of achieving a comprehensive picture of the global pattern of dust accumulation rates their controlling mechanisms and how those mechanisms may vary regionally the dust indicators and records of terrestrial and marine palaeoenvironments dirtmap data base has been established to provide a global palaeoenvironmental data set that can be used to validate earth system model simulations of the dust cycle over the past 150 000 years

quaternary aeolian activity of eastern europe a poland case study abstract the emergence of the pleistocene aeolian processes and their intensity was revealed through morphoscopy the observation and analysis of quartz grain shape and microtexture sediments from 39 cored boreholes and three outcrops located in central and eastern poland were analysed using methodology developed in 1942 by cailleux to identify past wind action this method is based on the recognition of the degree of roundness observed on quartz grains along with their surface typology matt or shiny the obtained results allowed us to separate seven distinct periods where the content of quartz grains with matt surfaces and varying degrees of roundness increased indicating the presence of an aeolian environment these processes were different in their nature and intensity with the wind action periods varying from long lasting and very intense identified across the entire research area to periods with low intensity and local wind action events these periods can be correlated with the advance of oldest glacials the narevian nidanian mis 36 34 mis 22 the sanian 1 mis 16 the sanian 2 mis 12 the advance and retreat of the odranian ice sheet mis 6 maximum stadial and the odranian glaciation mis 6 post maximum stadial wartanian these aeolian processes lead to the formation of coversands and fluvial sediments that are rich in aeolianized grains

the evolution of a terrace sequence along the manas river in the northern foreland basin of tian shan china as inferred from optical dating abstract the tian shan range lies in the actively deforming part of the india asia collision zone the uplift rate and deformation pattern of the tian shan are important for understanding the dynamics of crustal deformation in the region the river terraces in northern tian shan provide key records of past changes in climate and or regional tectonics in this study a terrace sequence along the manas river in a tectonically active zone in the northern foreland basin of tian shan is investigated six river terraces were identified and dated using optically stimulated luminescence osl the results show that the six terraces were abandoned at 0 5 ka 1 4 ka 3 1 ka 4 0 ka 12 4 ka and 19 9 ka respectively together with high resolution global positioning system gps measurements on the terrace treads the fluvial history of manas river is reconstructed from 20 ka to 4 8 ka the height of the fluvial bed of manas river decreased at an average rate of 2 2 0 6 mm yr from 4 8 ka to the present the height of the fluvial bed decreased at an average rate of 13 5 0 6 mm yr corresponding to intensified incision of manas river during the late holocene this accelerated incision is very likely caused by the tectonic forces rather than climatic influences alone suggesting that the tectonic uplift activity was significantly intensified since 4 8 ka in the northern piedmont of tian shan other controlling factors on the incision of manas river are also discussed

fluvial incision and tectonic uplift across the himalayas of central nepal the pattern of fluvial incision across the himalayas of central nepal is estimated from the distribution of holocene and pleistocene terraces and from the geometry of modern channels along major rivers draining across the range the terraces provide good constraints on incision rates across the himalayan frontal folds sub himalaya or siwaliks hills where rivers are forced to cut down into rising anticlines and have abandoned numerous strath terraces farther north and upstream in the lesser himalaya prominent fill terraces were deposited probably during the late pleistocene and were subsequently incised the amount of bedrock incision beneath the fill deposits is generally small suggesting a slow rate of fluvial incision in the lesser himalaya the terrace record is lost in the high range where the rivers are cutting steep gorges to complement the terrace study fluvial incision was also estimated from the modern channel geometries using an estimate of the shear stress exerted by the flowing water at the bottom of the channel as a proxy for river incision rate this approach allows quantification of the effect of variations in channel slope width and discharge on the incision rate of a river the determination of incision rates requires an additional lithological calibration the two approaches are shown to yield consistent results when applied to the same reach or if incision profiles along nearby parallel reaches are compared in the sub himalaya river incision is rapid with values up to 10 15 mm yr it does not exceed a few millimeters per year in the lesser himalaya and rises abruptly at the front of the high range to reach values of 4 8 mm yr within a 50 km wide zone that coincides with the position of the highest himalayan peaks sediment yield derived from the measurement of suspended load in himalayan rivers suggests that fluvial incision drives hillslope denudation of the landscape at the scale of the whole range the observed pattern of erosion is found to closely mimic uplift as predicted by a mechanical model taking into account erosion and slip along the flat ramp flat geometry of the main himalayan thrust fault the morphology of the range reflects a dynamic equilibrium between present day tectonics and surface processes the sharp relief together with the high uplift rates in the higher himalaya reflects thrusting over the midcrustal ramp rather than the isostatic response to reincision of the tibetan plateau driven by late cenozoic climate change or late miocene reactivation of the main central thrust

timing of the tianshan mountains uplift constrained by magnetostratigraphic analysis of molasse deposits abstract the tianshan mountains lie in the actively deforming part of the india asia collision zone the thrust faulting and folding of the neogene and quaternary sediments forming linear roughly east west anticlines at the northern and southern borders of the orogenic belts indicate crustal shortening and thickening in late cenozoic time detailed magnetostratigraphic studies of the molasse deposits of the folded neogene and quaternary strata in the northern edge of the tianshan mountains indicate that the onset of uplift occurred at 7 ma deposition of the thick conglomerates between 7 and 2 58 ma in the studied region was mainly in response to the tectonic uplift while the accumulation of the early pleistocene conglomerates xiyu formation was mostly controlled by both tectonics and climatic cooling our results indicate that the present high relief of the tianshan mountains is the result of two dominant phases of uplift occurring at about 7 2 58 ma and the early pleistocene

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

multiphase breakdown sequence of collapse doline morphogenesis an example from quaternary aeolianites in western australia abstract the morphology of collapse dolines varies according to their maturity and effectiveness of the removal of collapsed material in addition the variable balance between various geomorphic processes due to local geologic hydrologic and climatic settings results in a diverse morphology of collapse dolines and dynamics of their morphogenesis a single generalised proposed sequence of collapse dolines morphogenesis has therefore limited value and more detailed study is needed in terrains which differ in terms of geology hydrology and or climate there is a particularly well exposed karst in stockyard gully national park in the southwestern coastal part of western australia formed in quaternary aeolianites consisting of a dense field of collapse dolines up to 100 m in diameter and on average 10 m deep extensive field work combined with available data of local rock stratigraphy and a comparison to collapse dolines worldwide revealed that the principal processes of collapse doline formation in stockyard gully national park are similar to processes responsible for collapse doline formation worldwide i e collapses above underground chambers and removal of the collapsed material however rock characteristics in the area influence their morphometry due to the mechanical weakness of aeolianite compared to well cemented limestones and a surface calcrete layer with stronger mechanical resistance than underlying aeolianite consequently we propose a new 4 stage multiphase breakdown sequence of collapse doline morphogenesis in aeolianites divided into cave dome calcrete caprock dome young collapse doline and mature collapse doline calcrete caprock dome is stabilised by the uppermost well cemented calcrete and represents a distinctive phase just before the final breakdown to form an actual collapse doline

late quaternary alluvial sequence and uplift driven incision of the urumqi river in the north front of the tian shan northwestern china abstract this work focuses on the driving force behind the late quaternary river incision and terrace formation of the urumqi river in the north piedmont of the tian shan northwestern china field investigations on geomorphic surfaces terrace deposits and its underlying bedrock identify four most significant features which creates a local applicable framework for subdivision of the late quaternary terrace sequence in the study area nine stepped river terraces are defined and designated as t 1 to t 9 increasing systematically in elevation morphologically the highest t 9 correlates with the oldest alluvial fan f 1 of the urumqi river river incision and the resultant abandonment of fan f 1 are chronologically constrained at ca 550 ka the stratigraphic geometry of the saerqiaoke anticline a structure developing at the fan end of f 1 reveals the existence of growth strata implying continuous growth of this fold when the f 1 alluvial sediments were deposited in the range front of the urumqi river growth of the saerqiaoke anticline has derived tectonically from uplift and basinward thrusting of the tian shan range such thrusting and basinward extension of the range are expected to force rock uplift of the headwater of the urumqi river with respect to the chaiwopu basin to the north and thus river incision occurring at ca 550 ka during the subsequent period several younger terraces have been formed in response to the further uplift of the saerqiaoke anticline as well as climate changes during glacial interglacial transitions in the present study area the total incision during quaternary comes close to 400 m with about 85 contribution likely attributed to rock uplift of the saerqiaoke anticline

magnetochronology of the upper cenozoic strata in the southwestern chinese tian shan rates of pleistocene folding and thrusting abstract the southwestern chinese tian shan of central asia is an actively deforming part of the indian asian collision system paleomagnetic investigations of two plio pleistocene terrestrial successions provide the first detailed magnetostratigraphy for the upper cenozoic strata in this region paleomagnetic samples were collected from 358 sites within the atushi formation and xiyu formation across the atushi talanghe anticline near atushi thermal demagnetization behavior reversal and fold tests of paleomagnetic stability indicate that the characteristic remanence directions were acquired before tilting and folding of the strata a composite magnetostratigraphic section for this sequence correlates with the mammoth subchron to the jaramillo subchron between 3 3 and 1 07 myr of the geomagnetic polarity timescale of cande and kent j geophys res 100 1995 6093 6095 the mean declination 349 3 in the boguzihe section indicates a counterclockwise vertical axis rotation 11 2 during the past 1 4 myr the conglomeratic xiyu formation is time transgressive along its progradational contact with the underlying atushi formation across a map distance of 6 km the basal contact ranges from less than 1 0 myr in the ganhangou section to 1 9 myr in the boguzihe section to the southwest and to 2 8 myr on the northwest limb of the anticline northeastward lateral propagation and growth of the atushi talanghe anticline initiated at 1 4 myr in the boguzihe and 1 2 myr in the ganhangou the cross section in the boguzihe provides a conservative maximum estimate of shortening rate of 3 3 4 4 mm yr and uplift rate of 3 mm yr this rate represents about half of the geodetically determined shortening rate between the northern tarim basin and the kyrgyz tian shan wang et al acta seismol sin 22 2000 263 270 reiger et al earth planet sci lett 191 2001 157 165 during fold growth over the past 1 4 myr the crest of the atushi talanghe anticline eroded at an average rate of 2 6 2 7 mm yr

speleogenesis in highly geodynamic contexts the quaternary evolution of monte corchia multi level karst system alpi apuane italy abstract the mt corchia karst system is one of the most important and famous caves in the world different from many other large caves here the geological structure has had only a minor role on the vertical multi level pattern of the cave a detailed geomorphic and morphometric analysis of the cave and a preliminary study of cave sediments along with new datings of speleothems allow us now to depict the multistage evolution of this cave which produced at least three major paleo phreatic levels related to different base level stages the analysis of the directions of cave passages shows that the three main phases have different orientations which can be attributed to the different surface morphology during speleogenesis in former times chronological constraints and geomorphic features suggest that the upper part of mt corchia cave developed during the end of pliocene in a stage of favourable climatic conditions and with a moderate tectonic uplift rate the morphological features and the nature of sediments in the upper paleo phreatic level at 1350 1450 m above present sea level apsl imply the occurrence of a wide allogenic catchment area this drainage pattern persisted also in the following stage during a significant but slow lowering of the base level which allowed the formation and the intense vadose rearrangement of the epi phreatic network around 1100 1250 m apsl an uplift stage in the early pleistocene caused the capture of the basins and the loss of allogenic feeding a third epi phreatic level was formed at around 900 m apsl when the catchment area was reduced to the present extent of carbonate rock more than 1 ma ago the recent evolution is due to rapid uplift and to the progressive incision of surrounding basins which led to the lowering of the local base level and to a readjustment of the cave system in order to adapt to a new equilibrium with the present elevation of the springs

neogene uplift of the tian shan mountains observed in the magnetic record of the jingou river section northwest china the tian shan mountains constitute central asia s longest and highest mountain range understanding their cenozoic uplift history thus bears on mountain building processes in general and on how deformation has occurred under the influence of the india asia collision in particular in order to help decipher the uplift history of the tian shan we collected 970 samples for magnetostratigraphic analysis along a 4571 m thick section at the jingou river xinjiang province china stepwise alternating field and thermal demagnetization isolate a linear magnetization component that is interpreted as primary from this component a magnetostratigraphic column composed of 67 polarity chrons are correlated with the reference geomagnetic polarity timescale between 1 ma and 23 6 ma with some uncertainty below 21 ma this correlation places precise temporal control on the neogene stratigraphy of the southern junggar basin and provides evidence for two significant stepwise increases in sediment accumulation rate at 16 15 ma and 11 10 ma rock magnetic parameters also undergo important changes at 16 15 ma and 11 10 ma that correlate with changes in sedimentary depositional environments together with previous work we conclude that growth history of the modern tian shan mountains includes two pulses of uplift and erosion at 16 15 ma and 11 10 ma middle to upper tertiary rocks around the tian shan record very young 5 ma counterclockwise paleomagnetic rotations on the order of 15 to 20 which are interpreted as because of strain partitioning with a component of sinistral shear that localized rotations in the piedmont

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

a 190 ky record of lithogenic grain size on the namibian slope forging a tight link between past wind strength and coastal upwelling dynamics abstract we inferred wind strength variations at the namibian coast and its effect on upwelling intensity over the last 190 ky by comparing grain size data and alkenone based sea surface temperatures ssts from one sediment core located on the upper slope off luderitz 25 6 s 13 38 e the wind strength proxy was defined by partitioning terrigenous grain size distributions gsds into two sub populations owing to a simple statistical model the fine poorly sorted component is assumed to include both fine aeolian dust and hemipelagic mud carried by rivers or winnowed from the shelf those two fractions are assumed to have been identically sorted during settling in the water column and are not distinguished by our approach the mode of the coarse well sorted sub population displays rapid high amplitude variations through time we ascribe a strictly aeolian origin to this component and consider that low altitude winds are able to carry coarse grained particles to the ocean as shown by grain size measurements of present dust material from the adjacent continent stuut j b w prins m a schneider r r weltje g j jansen j h f postma g 2002 a 300 kyr record of aridity and wind strength in southwestern africa inferences from grain size distributions of sediments on walvis ridge se atlantic mar geol 180 221 233 variations in the coarse grained dust diameter are closely correlated with sst changes past ssts records from the namibian upper slope have been previously hypothesized as reflecting upwelling intensity combined with occasional injection of warm water from the angola dome we challenge this view in considering that past long term ssts variations are primarily induced by the wind strength and witness coastal upwelling intensity early mis 6 is the only period with evidences of warm poleward water intrusion at the core site the windiest conditions occurred during isotopic stages 3 and 4 the wind strength proxy defined in this study can be used confidently as an independent proxy for past upwelling intensity over the last two climatic cycles

paleozoic accretion and cenozoic redeformation of the chinese tien shan range central asia the tien shan range in central asia contains two late paleozoic sutures the older southern suture marks the collision of a passive margin at the north of the tarim block and an active continental margin subduction under the latter was to the north the younger northern suture separates a northern carboniferous island arc from an active continental margin developed over a south dipping subduction zone the subduction direction under the island arc is unknown mesozoic elastics were deposited over the doubly sutured orogen rate and energy of sedimentation waned until deposition of oligocene conglomerates above a regional unconformity interpreted as marking the onset of deformation induced by the india asia collision molasse deposition accelerated in pliocene and quaternary time and deposition continues today as active thrusts generate relief paleozoic structures control the gross divergence of cenozoic thrusts across the orogen

late miocene northward propagation of the northeast pamir thrust system northwest china 2015 american geophysical union piggyback basins on the margins of growing orogens commonly serve as sensitive recorders of the onset of thrust deformation and changes in source areas the bieertuokuoyi piggyback basin located in the hanging wall of the pamir frontal thrust provides an unambiguous record of the outward growth of the northeast pamir margin in northwest china from the miocene through the quaternary to reconstruct the deformation along the margin we synthesized structural mapping stratigraphy magnetostratigraphy and cosmogenic burial dating of basin fill and growth strata the bieertuokuoyi basin records the initiation of the pamir frontal thrust and the takegai thrust 5 6ma as well as clast provenance and paleocurrent changes resulting from the pliocene to recent uplift and exhumation of the pamir to the south our results show that coeval deformation was accommodated on the major structures on the northeast pamir margin throughout the miocene to recent furthermore our data support a change in the regional kinematics around the miocene pliocene boundary 5 6ma rapid exhumation of ne pamir extensional domes coupled with cessation of the kashgar yecheng transfer system on the eastern margin of the pamir accelerated the outward propagation of the northeastern pamir margin and the southward propagation of the kashi atushi fold and thrust belt in the southern tian shan this coeval deformation signifies the coupling of the pamir and tarim blocks and the transfer of shortening north to the pamir frontal faults and across the quasi rigid tarim basin to the southern tian shan kashi atushi fold and thrust system

tectonic uplift sea level changes and plio pleistocene evolution of a coastal karst system the mount saint paul palawan philippines the st paul karst palawan philippines is a tropical coastal karst consisting of towers cones huge depressions and large caves this area hosts the puerto princesa subterranean river ppsr 24 km long whose main entrance is a large spring along the coast and which is one of the largest cave complexes in eastern asia a geomorphological study performed by several field surveys and a morphometric analysis of the digital terrain model dtm and 3d cave models allowed formulation of a first evolutionary framework of the karst system the dtm was extracted from maps and aerial photographs in order to find different generations of relict landforms through the morphometric analysis of topographic surface and karst landforms several features suggest a long and multi stage evolution of the karst whose age ranges from pliocene to present the southern and northern sectors of the area differ in their altimetric distribution of caves in the southern sector some large caves lie between 300 and 400 m asl and were part of an ancient system that developed at the base level of a past river network in the northern sector some mainly vadose caves occur with a phreatic level at 120 130 m asl an important phase of base level cave development is well documented in the inactive passages of ppsr at 50 80 m asl morphological features such as horizontal solution passages and terraced deposits suggest a phase of stillstand of the base level which is recorded in the topography as low relief surfaces at 40 50 m asl the age of this phase is probably early pleistocene on the basis of assumed uplift rates the more recent caves are still active being located at the current sea level but they show more than one cycle of flooding and dewatering with calcite deposition in the ppsr several morphologic features such as two main water level notches at 12 4 and 7 7 m asl and terraced alluvial deposits suggest that the lower and active level passed through more than two high stands of sea level and so it could have formed throughout most of the middle late pleistocene copyright 2010 john wiley sons ltd

cenozoic uplift exhumation and deformation in the north kuqa depression china as constrained by u th he thermochronometry placing spatial and temporal constraints on deformation uplift and exhumation using thermochronology methods can shed light on cenozoic orogenic evolution in the kuqa foreland new apatite u th he and previously published apatite fission track thermochronology are combined with vitrinite reflectance data and modeling to compile a low temperature multi stage thermal history of tectonic uplift thrust and exhumation a rapid uplift and exhumation event originated in south tianshan during the eocene 46 ma with systematic younging of mean apatite u th he ages from north to south from the margin towards the interior uplift and exhumation south edge of the biyoulebaoguzi anticline in the northern monocline belt at 36 ma with more than 3400 m of stratum denuded subsequently deformation and uplift south edge of the biyoulebaoguzi anticline in the northern monocline belt at 36 ma with more than 3400 m of stratum denuded subsequently deformation and uplift extended to the northern edge of kelasu yiqikelike at 10 ma and then at 6 ma the kanyaken anticline formed and uplifted resulting in 3000 3700 m of overburden erosion the data support sequential southward propagating deformation and uplift inferred exhumation in the north kuqa depression during the cenozoic probably as a result of the collision of india with asia far to the south of the tianshan

equivalency of geologic and geodetic rates in contractional orogens new insights from the pamir frontal thrust across contractional orogens the equivalency between decadal convergence rates from geodetic gps data and geologic shortening rates at time scales of thousands or millions of years has rarely been documented here we present an example from the northern margin of chinese pamir where the main pamir thrust is tectonically quiescent and recent deformation is concentrated on the pamir frontal thrust pft based on dated and faulted fluvial terraces magnetostratigraphy and mapping the horizontal shortening rate of the pft is 6 7 mm a at time scales of both 18 4 ka and 0 35 ma comparable to the geodetic rate of 6 9 mm a across the same zone implying that modern geodetic rates are a reasonable proxy for geologic rates since 0 35 ma comparing this example with studies in other contractional orogens we conjecture that a match or mismatch of geologic geodetic rates typically depends on the time scale of observation fault geometry and fault mechanics 2012 by the american geophysical union