late quaternary river incision rates and rock uplift pattern of the eastern qilian shan mountain china abstract the uplift rate and pattern of the qilian shan mountain which lies in the northeast margin of the tibetan plateau are key to understanding the dynamics of crustal deformation in the northeastern tibetan plateau in this work late quaternary terraces in seven river valley sections in the eastern qilian shan mountain are studied to determine terrace abandonment ages by osl optical simulating luminescence and terrace heights by gps global positioning system surveys river incision rates since 76 ka bp are calculated ranging from 0 37 mm a to 1 49 mm a distribution of river incision rates shows that higher river incision rates 0 85 1 49 mm a are located at the rivers upstream reaches where mean mountain elevation is 4000 m and relatively lower incision rates 0 32 0 62 mm a are located at the mountain front where the mean mountain elevation is

geomorphic constraints on listric thrust faulting implications for active deformation in the mackenzie basin south island new zealand 1 deformed fluvial terraces preserved over active thrust related folds record the kinematics of folding as fault slip accumulates on the underlying thrust in the mackenzie basin of southern new zealand the kinematics revealed by folded fluvial terraces along the active ostler and irishman creek fault zones are inconsistent with traditional models for thrust related folding in which spatially uniform rock uplift typically occurs over planar fault ramps instead warped and tilted terraces in the mackenzie are characterized by broad continuous backlimbs and abrupt forelimbs and suggest folding through progressive limb rotation by relating this pattern of surface deformation to the underlying thrust with a newly developed simple geometric and kinematic model we interpret both faults as listric thrusts rooted at depth into gently dipping planar fault ramps constraints on the model from detailed topographic surveying of deformed terraces ground penetrating radar over active fault scarps and luminescence dating of terrace surfaces suggest slip rates for the ostler and irishman creek faults of 1 1 1 7 mm yr and 0 5 0 7 mm yr respectively the predicted depth of listric faulting for the ostler fault 0 7 0 2 0 1 km and the irishman creek fault 1 3 0 5 0 1 km generally agrees with geophysical estimates of basin depth in the mackenzie and suggests control of preexisting basin architecture on the geometry of active thrusting despite the potential effects of changes in fault curvature and hanging wall internal deformation the methodology presented here provides a simple tool for approximating the kinematics of surface deformation associated with slip along listric or curviplanar thrust faults

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr

geomorphic evidence for northeastward expansion of the eastern qilian shan northeastern tibetan plateau abstract the eastern qilian shan is a tectonically active region consisting of a series of faults with bounded intermountain basins and is located within the transition zone between the mainland tibetan plateau and the alax block active deformation affecting the topography in this region can be quantified based on geomorphic indices therefore we applied the geomorphic indices hypsometry and stream power incision model to evaluate the tectonic deformation pattern of the eastern qilian shan hypsometric curves and s a plots of the selected seven rivers were determined hi values of every single sub basins were also calculated the results show that the local topographic evolution of the eastern qilian shan is in pre steady state and will soon reach its equilibrium state according to the analysis of regional climate condition e g rainfall and glaciers distribution and fault characteristics it is suggested that abundant glacial snowmelt water sustains fluvial incision and tectonic deformation from sustained northeastward expansion of the tibetan plateau is the main reason for the landscape growth combining the research of the deep electric structure beneath the gulang boundary zone we claimed that the eastern qilian shan even the northeastern tibet has been growing and expanding northeastward since the middle miocene and its leading edge now is the hexibao sidaoshan fault on the premise of synthetically considering the western and middle parts of the qilian shan it is suggested that the hexibao sidaoshan fault area will rise into a mountain in 1 2 ma

numerical model predictions of autogenic fluvial terraces and comparison to climate change expectations terraces eroded into sediment alluvial and bedrock strath preserve an important history of river activity river terraces are thought to form when a river switches from a period of slow vertical incision and valley widening to fast vertical incision and terrace abandonment consequently terraces are often interpreted to reflect changing external drivers including tectonics sea level and climate in contrast the intrinsic unsteadiness of lateral migration in rivers may generate terraces even under constant rates of vertical incision without external forcing to explore this mechanism we simulate landscape evolution by a vertically incising meandering river and isolate the age and geometry of autogenic river terraces modeled autogenic terraces form for a wide range of lateral and vertical incision rates and are often paired and longitudinally extensive for intermediate ratios of vertical to lateral erosion rate autogenic terraces have a characteristic reoccurrence time that scales with the time for relief generation there is a preservation bias against older terraces due to reworking of previously visited parts of the valley evolving spatial differences in bank strength between bedrock and sediment reduce terrace formation frequency and length favor pairing and can explain sublinear terrace margins at valley boundaries age differences and geometries for modeled autogenic terraces are consistent in cases with natural terraces and overlap with metrics commonly attributed to terrace formation due to climate change we suggest a new phase space of terrace properties that may allow differentiation of autogenic terraces from terraces formed by external drivers

multiple climatic cycles imprinted on regional uplift controlled fluvial terraces in the lower yalong river and anning river se tibetan plateau abstract the development of fluvial systems on the southeastern margin of the tibetan plateau is linked to significant and rapid late cenozoic uplift the relatively complete fluvial terrace sequence preserved along the yalong river valley and that of its tributary the anning river provides an excellent archive for studying the development of terraces in rapidly uplifting mountainous areas this study reveals that terrace development is predominantly controlled by multiscale climate cycles and long term uplift as shown by terrace dating sedimentary characteristics and incision rates at least six alluvial terrace units were identified in 20 transverse sections through the terraces along about a 600 km length of river and were dated using electron spin resonance esr and optically stimulated luminescence osl the climatostratigraphic positions of the terrace deposits and their respective age constraints suggest that fluvial aggradation was concentrated during marine isotope stages mis 32 22 18 4 2 and the younger dryas yd and that incision occurred during the succeeding cold to warm transitions the changes in fluvial style marked by terraces 6 5 and 4 predominantly occurred in synchrony with the 100 ka milankovitch climate cycles while terraces 3 and 2 were controlled by the obliquity driven 41 ka climate cycles finally the aggradation of terrace t1 occurred in response to the yd stadial during the intervening time between 0 72 and 0 063 ma terraces either did not form or were not preserved which may suggest that uplift rates varied through time and influenced terrace formation preservation the progressive valley incision recorded by these fluvial terraces cannot be entirely explained by climate cycling alone temporal and spatial variations in incision rates indicate that the continuing long term incision has been driven by uplift the temporal distribution of the incision rates reveals two rapidly uplifting stages in the southeastern tibetan plateau including an accelerated uplift that has been taking place since 0 06 ma the spatial distributions of differing incision rates reflect the geomorphological response to crustal shortening and differential uplift in this region

quaternary tectonic evolution of the pamir tian shan convergence zone northwest china the pamir tian shan collision zone in the western tarim basin northwest china formed from rapid and ongoing convergence in response to the indo eurasian collision the arid landscape preserves suites of fluvial terraces crossing structures active since the late neogene that create fault and fold scarps recording quaternary deformation using geologic and geomorphic mapping dgps surveys of deformed terraces and osl dating we create a synthesis of the active structures that delineate the timing rate and migration of quaternary deformation during ongoing convergence new deformation rates on eight faults and folds when combined with previous studies highlight the spatial and temporal patterns of deformation within the pamir tian shan convergence zone during the quaternary terraces spanning 130 to 8 ka record deformation rates between 0 1 and 5 6 mm yr on individual structures in the westernmost tarim basin where the pamir and tian shan are already juxtaposed the fastest rates occur on actively deforming structures at the interface of the pamir tian shan orogens farther east as the separation between the pamir tian shan orogens increases the deformation has not been concentrated on a single structure but rather has been concurrently distributed across a zone of faults and folds in the kashi atushi fold and thrust belt and along the ne pamir margin where shortening rates vary on individual structures during the quaternary although numerous structures accommodate the shortening and the locus of deformation shifts during the quaternary the total shortening across the western tarim basin has remained steady and approximately matches the current geodetic rate of 6 9 mm yr

post glacial range of variability in the conejos river valley southern colorado usa fluvial response to climate change and sediment supply effective river management strategies require an understanding of how fluvial processes vary both spatially and temporally here we examine the natural range of variability in the conejos river valley southern colorado through documentation of terrace morphostratigraphic and sedimentological characteristics as well as through investigation of sediment contributions from headwaters hillslopes and tributary streams additionally soil development and radiocarbon ages together with local and regional paleoclimate reconstructions were used to infer the range of processes acting in this system since de glaciation the conejos river has fluctuated between episodes of bedrock strath formation aggradation and vertical incision morphostratigraphic relationships soil development and radiocarbon ages enable us to propose a chronology for periods of alluvial deposition around 8 9 7 6 ka 5 5 ka and from 3 5 to 1 1 ka separated by intervals of fluvial incision we infer potential forcing mechanisms by utilizing multiple working hypotheses specifically we discuss the potential for increases in sediment supply during periods of 1 para glacial adjustment 2 climatic cooling 3 increased frequency of climate change and 4 increased fire frequency or severity we also consider the effects of changes in stream discharge and extreme storm occurrence we conclude that combinations of these processes operating at different times have contributed to sediment mobilization since de glaciation stream and landform morphology also varies longitudinally due to the influence of remnant glacial topography in particular valley bottom overdeepening at tributary junctions has resulted in incision and strath formation into unlithified glacial deposits i e fill cut terraces rather than bedrock in some reaches overall the conejos fluvial system has varied significantly both temporally and spatially since de glaciation and appears to be sensitive to changes in sediment supply related to holocene scale climate fluctuations this natural range of variability must therefore be a key consideration in any future stream management policies copyright 2012 john wiley sons ltd

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

interpreting climate modulated processes of terrace development along the colorado front range using a landscape evolution model flights of terraces that flank range fronts throughout the rocky mountains record episodic stream incision over the past 1 5 ma studies dating terraces in the denver basin along the colorado front range suggest that these high surfaces were formed during glacial intervals and were rapidly incised and abandoned during interglacials modulation of sediment supply or transport capacity associated with climate change related to glacial interglacial cycles have been suggested as possible drivers for the repeated aggradation and abandonment of these high surfaces potential mechanisms for increasing sediment supply and transport in rivers include variations over time in sediment flux from intermittently glaciated major valleys the efficiency of hillslope sediment transport and the magnitude and timing of rainfall intensity and stream flow in this study we use a landscape evolution model to determine whether any of these processes in isolation or in combination is sufficient to explain the observed rates and patterns of terrace formation and abandonment along the colorado piedmont cycles of channel aggradation and incision are apparent in the models when either mean rainfall intensity is varied or a glacial source of sediment is added the models suggest that in the absence of a large addition of sediment to the streams changes in stream power are necessary to allow channel aggradation and the planation of bedrock surfaces and increased sediment flux from hillslopes is necessary to match observations of increased denudation rates that coincide with the deposition of terrace capping gravels

distinguishing allogenic from autogenic causes of bed elevation change in late quaternary alluvial stratigraphic records abstract allogenic and autogenic mechanisms both cause changes in the bed elevation of rivers and thereby influence the characteristics of alluvial stratigraphic records asrs allogenic forcing mechanisms can be grouped into five categories whose relative influence varies with timescale climate tectonism base level land use land cover and direct human modification of channels late quaternary asrs are influenced by the greatest range of allogenic forcing variables with climate among the most important autogenic mechanisms of bed elevation change are ubiquitous throughout fluvial systems and are always time transgressive autogenic bed elevation change propagates through drainage networks at predictable rates and results in a time space envelope within which its effects are capable of operating asrs that can be correlated over geographical areas large enough and time intervals small enough to exist outside this envelope most likely result from allogenic forcing this formulation represents a quantitative and geographic set of threshold criteria for distinguishing between autogenic and allogenic mechanisms over late quaternary timescales 10 2 to 10 5 years in tectonically stable regions climate change is the dominant allogenic mechanism and therefore the first order control on the morphology sedimentology pedologic characteristics and chronology of alluvial stratigraphic records that meet or exceed the threshold criteria for demonstrating allogenic causality

relative dating of terraces of the owens river northern owens valley california and correlation with moraines of the sierra nevada abstract in the northern owens valley the owens river has cut and preserved three terraces uplifted above its modern floodplain we have analyzed soils and used other relative dating techniques in order to differentiate the terrace surfaces to correlate from the terraces to moraines of the eastern sierra nevada and to test the effects of relief and climatic differences on relative dating results most of the relative dating techniques attempted were successful in differentiating the terraces of the owens river sequence in addition weathering rinds soil descriptions and an early holocene 14 c date for the youngest terrace support correlation of the three terrace levels with the three post sherwin age glacial stages tioga tahoe and pre tahoe found in nearby canyons of the sierra nevada other relative dating techniques that are commonly employed however suggest distinct differences between the terrace and moraine sequences these differences probably reflect the difference in relief such that slow erosion of the moraine crests may have retarded soil development relative to the flat terrace surfaces and altered surface weathering processes use of relative dating analyses to correlate between dissimilar geomorphic systems requires caution but use of a broad range of techniques and absolute age calibration may make correlation possible

fluvial responses to late quaternary climate change in the shiyang river drainage system western china abstract as a drainage system located in arid western china the shiyang river combined with considerable fluvial strata and landform information provides an environmental context within which to investigate fluvial responses to late quaternary climate change sedimentological analysis and optically stimulated luminescence osl dating enabled us to reconstruct the processes and fluvial styles of three sedimentary sequences of the shagou and hongshui rivers in the shiyang drainage system our results present a variety of river behaviors during the late quaternary in these areas in the upstream shiyang river zhangjiadazhuang zjdz profile of the shagou was dominated by aggradation and a meandering channel pattern at 10 6 4 2 ka while a noticeable channel incision occurred at 4 2 ka followed by lateral channel migration in the downstream shiyang river datugou dtg profile of the hongshui was an aggrading meandering river from 39 7 to 7 2 ka while channel incision occurred at 7 2 ka another downstream profile wudunwan wdw of the hongshui was also characterized by aggradation from 22 4 to 4 8 ka however its channel pattern shifted from braided to meandering at 13 ka a discernable downcutting event occurred at 4 8 ka followed by three channel aggradation and incision episodes prior to 1 8 ka the last 1 8 ka has been characterized by modern channel and floodplain development the fluvial processes and styles investigated have a close correlation with late quaternary climate change in the shiyang river drainage during cold phases the wdw reach was dominated by aggradation with a braided channel pattern during warm phases the rivers that we investigated were also characterized by aggradation but with meandering channel patterns channel incision events and changes of fluvial style occurred mainly during climate transitions

river response to an active fold and thrust belt in a convergent margin setting north island new zealand high resolution digital elevation data topsar 10 m grid are used to reconstruct late quaternary growth histories of subtle folding in the wairarapa fold and thrust belt north island new zealand outcrop data of deformed latest miocene and younger strata are combined with observations of warped and faulted late quaternary terrace surfaces to unravel the geomorphic and structural history of the huangarua river valley optically stimulated luminescence osl dating of loess that accumulated on these strath terraces and paleosol stratigraphy allow temporal correlation among the terraces and with glacial climate cycles since the last interglaciation these data indicate that five intervals of strath cutting occurred at 125 60 70 30 15 and 10 ka strath beveling is largely independent of local folding or regional base level change we hypothesize that straths are cut when an increase in sediment supply during cool climatic periods brings river sediment load and river transport capacity into balance in the wairarapa strath cutting events appear to occur near the end of cool climatic cycles this study shows that the identification of subtle departures from regional topographic trends becomes practical when a high resolution dem is available after subtraction of an average valley gradient from the digital topography the residual topography on the terrace treads reveals cross valley and longitudinal tilting although rates of folding are slow and the magnitude of deformation is commonly limited to less than a few tens of meters these topographic anomalies define fold axes that coincide with subsurface structures when combined with time control these anomalies serve to define the patterns and rates of fold growth over the past 125 kyears

neogene fluvial sediments in the northern jinshaan gorge china implications for early development of the yellow river since 8 ma and its response to rapid subsidence of the weihe shanxi graben abstract origin of the neogene fluvial sediments in the jinshaan gorge is a significant issue concerned with development of the yellow river field investigation shows that the bedrock topography underneath the neogene fluvial sediments is an up to 8 10 km wide valley the tanghsien phase valley the tanghsien phase bedrock valley is made up of two flat terrace surfaces altitude evidence shows the neogene fluvial sediments almost continuously distribute on a successively southward lowering bedrock valley along the gorge sedimentology analysis based on roundness and gravel composition is performed and two types of neogene gravels are classified the first type of gravels shows the same provenance as those on the lower quaternary terraces namely they were abandoned by the same river a south flowing river through the jinshaan gorge area or the ancient yellow river the second type of gravels interbedded with the baode red clay could be alluvium from the luliang mountain magnetostratigraphy indicates that the oldest fluvial sediments in the hequ and baode areas can be constrained to ca 8 ma and the sediments have a westward younger variation trend the westward younger fluvial sediments during 8 3 7 ma imply that the ancient yellow river through the modern jinshaan gorge area might have undergone a fairly long time lateral erosion progress and have shaped the broad valley under the circumstance of stable climate and tectonics owing to pulsed subsidence of the weihe shanxi graben driven by northeastward growth of the tibetan plateau since the pliocene the lateral planation progress of the yellow river was broken up and the inset jinshaan gorge was finally formed

numerical simulations of bedrock valley evolution by meandering rivers with variable bank material bedrock river valleys are fundamental components of many landscapes and their morphologies from slot canyons with incised meanders to wide valleys with strath terraces may record environmental history several formation mechanisms for particular valley types have been proposed that involve changes in climatic and tectonic forcing but the uniqueness of valley evolution pathways and the long term stability of valley morphology under constant forcing are unknown and are not predicted in existing numerical models for vertically incising rivers because rivers often migrate more rapidly through alluvium than through bedrock we explore the hypothesis that the distribution of bank materials strongly influences river meandering kinematics and can explain the diversity of bedrock river valley morphology simulations using a numerical model of river meandering with vector based bank material tracking indicate that channel lateral erosion rate in sediment and bedrock vertical erosion rate and initial alluvial belt width explain first order differences in bedrock valley type that bedrock bound channels can evolve under steady forcing from alluvial states and that weak bedrock and low vertical incision rates favor wide shallow valleys while resistant bedrock and high vertical incision rates favor narrow deep valleys during vertical incision sustained planation of the valley floor is favored when bedrock boundaries restrict channel migration to a zone of thin sediment fill the inherent unsteadiness of river meandering in space and time is enhanced by evolving spatial contrasts in bank strength between sediment and bedrock and can account for several valley features including strath terraces and underfit valleys commonly ascribed to external drivers

terrace sequence along the yushanguxi river in the southern piedmont of tian shan and its relationship to climate and tectonics in northwestern china abstract controversies persist regarding the formation of terraces under the control of tectonic factors or climatic changes this work focuses on the yushanguxi river in the southern piedmont of tian shan which is an intense tectonic uplift area where the terraces are very developed and the river has deeply downcut nine main terraces are distinguished labelled t1 to th from youngest to oldest based on the interpretation of a high resolution remote sensing image field investigations and detailed surveying with differential gps the results of the determination of 10be exposure and 14c show abandoned ages of 2 1 ka for t1 4 1 ka for t2 4 2 ka for t3 8 2 ka for t4 18 1 ka for t5 18 8 ka for t6 102 1 ka for t7 100 6 ka for t81 113 9 ka for t82 144 6 ka for th1 210 7 ka for th2 and 284 3 ka for th3 since 18 ka the incision rate began to increase from 0 6 mm a 1 to 12 mm a 1 which is obviously higher than the fault slip rate of 0 7 mm a 1 we suggest that the rapid downcutting along the yushanguxi river during the holocene has mainly been caused by frequent climate fluctuations

late quaternary deposition and incision sequences of the golmud river and their environmental implications abstract golmud river is a large river that originates from the kunlun mountains and drains into the qaidam basin on northern tibetan plateau well developed fluvial terraces in the river valley record complex history of tectonic movements and climate changes in this area the current study investigated fluvial terraces in three cross sections along the river xiaogangou nachitai and sanchahe the ages of the terraces were constrained using optically stimulated luminescence osl and radiocarbon dating methods the results characterize two stages of fluvial landform evolution since the late quaternary the sanchahe deposition stage 82 16 ka and the golmud incision stage 16 ka until now during the deposition stage tectonic movements were relatively stable which drove the deposition meanwhile the enhanced glaciations and precipitation during the last glacial promoted the aggradations in the river valley as well during the incision stage four substages at 16 13 ka 13 11 ka 11 5 ka and 5 ka till now are identified these substages correspond to the incision of the four terraces the incision was mainly driven by the tectonic uplift after the last glacial maximum

ice volume forcing of east asian winter monsoon variations in the past 800 000 years particle size measurements of some typical loess soil samples taken in different localities of the chinese loess plateau demonstrate that the grain size ratio of 10 m can be used as an indicator of variations in intensity of the east asian winter monsoon winds grain size curves of the baoji and weinan sections show that this proxy indicator is very sensitive to loess soil alterations analytical results also suggest that during soil forming periods eolian dust accumulation was still substantial and hence loess deposition can be regarded as a nearly continuous process during the quaternary period in this study we compared the baoji grain size time series with the specmap marine isotope record with the objective of elucidating the dynamic linkage between changes in global ice volume and the winter monsoon circulation both records show good agreement at both time and frequency domains in particular the winter monsoon variations are also dominated by a 100 000 yr period over the past 800 000 yr it is thus inferred that direct local insolation forcing could be less important in driving the east asian winter monsoon variability and alternatively variations in glacial age boundary conditions may have played a key role in modulating and pacing its strength and timing

limits to quantifying climate driven changes in denudation rates with cosmogenic radionuclides abstract the hypothesis that climate change significantly modifies the denudation history of an orogen can be tested by reconstructing catchment wide denudation histories cosmogenic radionuclides measured in sediment deposits of known age e g a sequence of fluvial terraces offer one approach for quantifying catchment wide paleo denudation rates we present a numerical model and two case studies that evaluate the utility of this technique for reconstructing different denudation histories the concentration of cosmogenic beryllium 10 10 be is calculated for a sequence of sediments produced from climate driven variations in the mean denudation rate of a drainage basin at sea level and high latitude the model accounts for the nucleonic and muonic production and decay of 10 be as sediment is eroded and stored in deposits of different ages two scenarios for different climate driven denudation histories are considered 1 a sinusoidal variation in the input denudation rate with free parameters of periodicity 23 41 100 kyr amplitude 0 1 0 5 1 0 and mean denudation rate 0 01 0 1 1 0 mm yr 1 2 a climate driven denudation history based on oscillations of a global benthic foraminiferal oxygen isotope 18 o record over the last 2 myr results from both scenarios suggest cosmogenic radionuclides measured in a system with high denudation rates 0 5 mm yr 1 longer periodicity 100 kyr and low amplitude have the highest potential for reconstructing climate driven paleo denudation rates unfortunately the high denudation rates preferred in the theoretical consideration are not suitable for paleo denudation rate determination due to overprinting of nuclides accumulated during denudation by post depositional decay and irradiation hence a compromise between the capability to determine changes in paleo denudation rates and the determination of true denudation rates has to be accepted application of the model to previous data sets from northwest europe and southwest north america produce a good agreement but highlight the need for future work to consider how geomorphic processes e g landsliding respond to climate change and influence catchment wide denudation rates in addition other climate proxies than the benthic foraminiferal 18 o record should be used for specific sample locations

late pleistocene slip rate on a blind thrust in the western qilian shan nw china abstract in the western front of the qilian shan ne tibetan plateau a series of 5 fluvial t1 t5 terraces developed along the baiyang river are deformed across the shiyougou anticline which is related to the yumen beidahe yb blind thrust in this study we measure the deformed terraces across the anticline using differential gps which provides data for us to reconstruct the thrust fault geometry the ages of terrace abandonment are constrained by 10be exposure dating for t2 t4 and t5 to be 8 6 1 7 ka 21 6 1 4 ka and 48 4 2 1 ka respectively a four segment fault model is inferred with changing dips at depths of 0 3 0 1 km 2 2 0 1 km and 5 9 0 9 km combining terrace ages with the fault geometry model we derive a vertical slip rate of 0 9 0 1 mm yr and a shortening rate of 1 9 0 5 mm yr for the yb blind thrust this result suggests that the northern frontal thrust system accommodates only 30 of the total shortening rates across the western qilian shan the river incision rate has increased from 1 5 mm yr to 5 2 mm yr from the late pleistocene to the holocene the mismatch between river incision and rock uplift is likely related to climate change since the last glacial maximum

quaternary glaciations recorded by glacial and fluvial landforms in the shaluli mountains southeastern tibetan plateau abstract the shaluli mountains a tectonically controlled mountain range between the jinsha and yalong river rifts are located in southeastern tibetan plateau in the central shaluli mountains an ice cap of 3600 km 2 once developed on the haizi shan abundant glacial landforms are present on the haizi shan and in the surrounding river valleys together with the outwash terraces in the yazheku river the northeastern part of the haizi shan provides an ideal site to examine the quaternary glacial history of the region sedimentological and morphostratigraphical analysis field mapping and dating by electron spin resonance esr define at least seven major glacier advances in the haizi shan area six major glacier advances likely occurred during marine oxygen isotope stage mis 16 mis 14 12 mis 6 mis 3 early mis 2 and the global last glacial maximum these can be defined on the basis of esr dating and stratigraphical analysis of the glacial landforms in front of the kuzhaori glacial trough on the southern slope of the haizi shan the outwash terraces in the yazheku river also record four major glacier advances which occurred during mis 16 mis 12 mis 6 and mis 2 in addition the moraines preserved on the southwestern part of the haizi shan suggest that a glacial advance likely occurring during the lateglacial the extent of glaciation on the haizi shan decreased with time

upper crustal folding of the 2013 lushan earthquake area in southern longmen shan china insights from late quaternary fluvial terraces abstract a thrust earthquake of mw6 6 occurred on april 20 2013 near lushan county in the southern longmen shan at the east margin of tibetan plateau this earthquake did not produce a surface rupture zone and the late quaternary activities of the outcropped faults in the earthquake area were not obvious which increased the difficulty of studying the seismogenic structure this article took as the research target the middle reach of the qingyijiang river which traverses the earthquake area by surveying correlating the fluvial terraces studied quantitatively the late quaternary tectonic deformation and further discussed the seismotectonics the longitudinal profile of river terraces along the middle reach of the qingyijiang river reveals that the principal deformation style in the late quaternary was anticline type folding the folding is a typical fault bend fold involving the basement which is controlled by the newest flat ramp flat structure possibly formed in the pliocene or the early pleistocene across the fold the average shortening rate in the late quaternary is 0 6 1 3 mm yr about one third of the crustal shortening rate by gps data across the longmen shan fold and thrust belt and its foreland the foreland thin skinned structure developed in the cretaceous to paleogene strata in the earthquake area was passively involved into the fault bend folding in the late quaternary which commend the thrust ramp developing in a piggyback style the newest ramp appears to have controlled the rupture and the surface deformation of the 2013 lushan earthquake in the process of thrust sheet sliding toward foreland along the flat ramp flat detachment the ramp acts as a locking structure where earthquake ruptures the coseismic surface deformation seems to be passive folding of the thrust sheet climbing the ramp

stream response to quaternary tectonic and climatic change evidence from the upper weihe river central china abstract seven terraces of upper weihe river in the longxi basin on the north flank of the qinling mountains are capped with a succession of loess units and paleosols that correlate with the standard marine isotope chronology based on fieldwork and terrace ages which were determined using loess paleosol stratigraphy paleomagnetic optical stimulated luminescence osl and radiocarbon dating the results show that the fluvial fills were deposited during marine oxygen isotope stages miss 22 20 18 16 12 6 4 and 2 respectively whereas terracing occurred during glacial interglacial transitions this in turn points to eccentricity related climatic changes that may have driven recurrent incision and aggradation processes and significantly influenced the formation of staircase terraces of weihe river through the direct and indirect influence of both temperature and precipitation on fluviatile activity on the basis of terrace ages and its heights incision rates were enhanced from 865 to 412 ka 0 27 m ka decreased from 412 to 128 ka 0 09 m ka and increased from 128 ka to present 0 32 m ka

pleistocene climates in china dated by magnetic susceptibility the magnetic susceptibility of loess and interbedded soils in central china varies with the degree of pedogenesis and serves as a proxy measure of climate the concentration of magnetic minerals in the sediment is inversely proportional to sedimentation rates throughout the brunhes epoch susceptibility measurements combined with the reversal stratigraphy provide a time scale that is independent of astronomic chronology on this scale the susceptibility record closely parallels the oxygen isotope fluctuations in deep sea sediments suggesting a close interdependence of the chinese dust falls the volume of land based ice and global climate

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

assessing tectonic and climatic controls for late quaternary fluvial terraces in guide jianzha and xunhua basins along the yellow river on the northeastern tibetan plateau abstract this study focused on well preserved fluvial terrace sequences that span the past 100 ka in the guide jianzha and xunhua basins along the yellow river that drained the northeastern tibetan plateau new geomorphic stratigraphic sedimentologic and chronologic data from twelve depositional sequences within terraces yielded better constraints on rates of incision degradational and aggradational phases for the yellow river age control was established by sixteen osl ages on quartz grains from fluvial sediments three fluvial aggradational phases were identified between 100 and 80 ka 53 and 40 ka and 21 and 12 ka associated with terrace levels respectively at 120 to 95 61 to 45 and 25 to 15 m above river level these aggradational phases reflect multiple processes including enhanced fluvial discharge sediment availability with glaciation deglaciation and increased monsoonal precipitation the initiation of fluvial degradation was linked to mega floods released from landslide dammed lakes at ca 76 38 and 16 ka though these changes may also reflect variations in sediment load discharge relations with climate change the apparent net incision rate is 1 13 0 11 mm yr for the past 100 ka and is consistent with late cenozoic tectonic uplift rates 0 5 2 mm yr and recent gps based rates the fluvial dynamics of the upper reach of the yellow river was variably controlled by climate induced changes in discharge sediment load relations on stadial to interstadial timescales episodic mega floods from the breach of landslide dams and with net incision in the past 100 ka in response to tectonic uplift of the tibetan plateau

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

middle pleistocene to holocene fluvial terrace development and uplift driven valley incision in the se carpathians romania abstract this study reveals that in the se carpathians terrace development and fluvial incision during the middle pleistocene holocene are predominantly controlled by tectonic uplift as shown by terrace distributions and uplift amounts and rates the work focuses on a transect from the internal nappes and brasov intramontane basin western domain to the external nappes and focsani foredeep basin eastern domain new infrared stimulated luminescence ages were obtained and minimum terrace formation ages were determined to derive fluvial incision rates and thereby to constrain tectonic uplift in the eastern domain non uniform terrace distributions in adjacent sub parallel more active punta and less active usi a rivers and an eastward migrated fluvial incision from the orogen to the foredeep basin indicate tectonic uplift as dominant control on terrace development strath terraces in the western and eastern domains indicate repeated events of vertical fluvial incision and lateral erosion during the early middle pleistocene and late middle pleistocene holocene respectively these events imply successive recurrent disturbances of equilibrium conditions due to pulses of increased tectonic uplift fill terraces in the western domain show that initial aggradation periods were followed by uplift driven vertical incision during the late middle late pleistocene as fill terraces show a wide spread development climatic change and complex response cannot be excluded as contributing factors synchronous to terrace development loess deposition periods during the late middle late pleistocene and latest pleistocene and intercalated episodes of palaeosol formation during the late pleistocene imply comparable climatic conditions across the se carpathians dominant strath terraces of the eastern domain indicate stronger fluvial incision 240 m since the late middle pleistocene whereas older strath and younger dominant fill terraces of the western domain designate a lower amount 90 m since the early middle pleistocene middle pleistocene holocene fluvial incision rates document higher tectonic uplift in the external nappes and lower towards the western intramontane and eastern foredeep basins

late quaternary fluvial terraces of the romagna and marche apennines italy climatic lithologic and tectonic controls on terrace genesis in an active orogen abstract we synthesize a new fluvial terrace chronostratigraphy of the bidente and musone rivers cast within a broader european framework which forms the basis of a terrace genesis and river incision model for the northern apennines italy our model supported by terrace long profiles correlation to po foreland sediments 15 new radiocarbon dates and published numeric and relative stratigraphic ages highlights how drainage basin substrate drives concurrent formation of strath terraces in the bidente basin and fill terraces in the musone basin quaternary climate change paces the formative geomorphic processes through unsteady discharges of water and sediment in the weathering limited setting represented by the bidente basin siliciclastic detritus carves broad strath surfaces during glacial climates that are preserved as terraces as the river incises during the transition to an interglacial climate in contrast the transport limited and carbonate detritus dominated musone basin sees valleys deeply buried by aggradation during glacial climates followed by river incision during the transition to an interglacial climate incision of these rivers over the past 1 million years has been both unsteady and non uniform these and all po adriatic draining rivers are proximal to a base level defined by mean sea level and have little room for increasing their longitudinal profile concavities through incision particularly in their lower reaches despite periodic glacio eustatic drawdowns as a result the observed incision is best explained by rock uplift associated with active local fault or fold growth embedded in the actively thickening and uplifting apennine foreland

using fill terraces to understand incision rates and evolution of the colorado river in eastern grand canyon arizona 1 the incision and aggradation of the colorado river in eastern grand canyon through middle to late quaternary time can be traced in detail using well exposed fill terraces dated by a combination of optically stimulated luminescence uranium series and cosmogenic nuclide dating this fluvial history provides the best bedrock incision rate for this important landscape and highlights the complications and advantages of fill terrace records for understanding river long profile evolution and incision the use of fill terraces as distinct from strath terraces for calculating incision rates is complicated by the cyclic alluviation and incision they record in the example of the grand canyon this has led to various rates being reported by different workers and rates that tend to be overestimates in shorter records we illustrate that a meaningful long term bedrock incision rate of 140 m m y can be extracted from the grand canyon record by linking episodes when the colorado river is floored on bedrock variable incision rates reported in the greater region may be to some degree due to inconsistent calculations our data also highlight that the colorado river has been a mixed alluvial bedrock river through both time and space and has been a bedrock river for less than half of its pleistocene history this strong temporal variation combined with the varying bedrock the river encounters on its path heightens the challenge of understanding the tectonic climatic and drainage integration controls on the form and evolution of the colorado river s long profile

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 900 k y record of strath terrace formation during glacial interglacial transitions in northwest china the timing of the development of strath terraces with respect to climatic variability remains equivocal previous studies attribute strath terrace formation to glacial or interglacial climates or to variations in sediment and water fluxes that cause lateral erosion followed by vertical incision a chronology of strath terrace formation spanning similar to900 k y has been generated on the basis of loess paleosol couplets and paleomagnetic thermoluminescence and radiocarbon dating of strath terraces in the qilian shan of northeastern tibet repetitive stratigraphic and geomorphic patterns on each terrace indicate that they formed during glacial interglacial transitions long term bedrock incision rates and inferred rock uplift rates appear steady and unrelated to strath formation over the past 900 k y

quaternary drainage evolution of the datong river qilian mountains northeastern tibetan plateau china abstract drainage basins are useful recorders of tectonics and climate the datong river which drains the qilian mountains china is one of the most elongated river basins of the world how this unusual basin configuration was established remains unknown despite this area being ideal for assessing the controlling effects of tectonics and climate on the drainage evolution in this study we reconstruct the history of the drainage evolution of the datong river using integrated provenance methods u pb dating heavy mineral and gravel compositions and river terrace dating the drainage system of the modern datong river began to form at 1100 ka and the drainage basin was limited to the area of the lower modern datong river since then it has gradually extended through headward erosion the river channelized into the menyuan basin between 620 ka and 420 ka and it captured the upper datong river between 130 ka and 60 ka we suggest that the rapid uplift of the qilian mountains disrupted and longitudinally deflected the transverse rivers over the past 1100 ka additionally intensified precipitation and glacial meltwater enhanced the river incision and captured the middle and upper datong river during 620 420 ka and 130 60 ka respectively this model shows that the direction of drainage pattern evolution is controlled by tectonics and that the timing of drainage reorganization is controlled by climate change in the active fold thrust belt

age and palaeoclimatic significance of the loess of lanzhou north china extending in a broad arc that abuts the sandy non gobi deserts the loess plateau of northern china1 3 is one of the most massive accumulations of loess in the world the loess sequence is typically characterized by an alternation of silty or sandy loess with more clay rich palaeosols these alternations in conjunction with their enclosed faunas and distinctive mineralogies have been interpreted as reflecting pleistocene glacial interglacial cycles3 8 because it holds implications for the climatic and anthropological history of china9 10 the definition of a reliable chronological framework for loess deposition is of great interest recent palaeomagnetic studies4 5 have indicated that loess deposition in shaanxi province commenced 2 4 myr ago to assess the synchrony of loess accumulation across the loess plateau we have dated a 330 m thick loess sequence near lanzhou gansu province the magnetostrati graphical results reported here indicate that the base of this loess succession dates from 1 3 my r ago this young age in comparison to the shaanxi sequence is attributed to uplift along the northern fringe of the tibetan plateau11 that precluded early pleistocene loess preservation in this mountainous region palaeosols in the basal loess occur on average once every 25 kyr suggesting that climates conducive to soil forming events may have been modulated by orbital precession in the early pleistocene

terrestrial 10 be and electron spin resonance dating of fluvial terraces quantifies quaternary tectonic uplift gradients in the eastern pyrenees the 120 km longt et river flows out of the pyrenees to the mediterranean by displaying a mappable sequence of quaternary alluvial units between the pleistocene frontal moraines of the high range and the offshore sedimentary depocentres its 1400 km 2 watershed is well suited to quantifying gradients of topographic uplift five main generations of terrace treads had previously been inferred from constrasts in regolith weathering features but here we present the first radiometric age constraints based on 15 esr sediment burial ages covering the full sequence and 3 vertical tcn age profiles restricted to three mid sequence terraces analytically robust results were obtained for the oldest and uppermost terrace t5 esr age 1099 179 ka for t3b esr age 374 47 ka mis 10 and for t2 esr age 174 44 ka mis 6 these results are consistent with the contrasts in weathering grade of the deposits the tcn profiles only yielded minimum exposure ages but provided precise post depositional denudation rates for the fluvial terrace treads the land to sea geometry of the chronosequence also provided clues about valley incision rates in response to topographic uplift during the last 1 ma based on a critical review of similar data obtained for other mediterranean and atlantic watersheds in the pyrenees the full regional correlation reveals that post orogenic topographic uplift was substantial and relatively uniform throughout the entire mountain range patterns and magnitudes suggest a shared probably subcrustal driving mechanism of neogene and quaternary mountain growth with only subsidiary influence from isostasy and climatic forcing

late quaternary alluvial fan terraces langshan inner mongolia china abstract alluvial fan terraces of the langshan range in the northwestern hetao basin of northern china records uplift on range bounding faults and late quaternary climate change alluvial fan profiles are segmented in the central part of the range front which lack strath terraces that developed in the southwest sw and northeast ne parts the stream channels in the central part have higher channel gradients and lower ratios of the valley floor width to valley height v four episodes of alluvial fan terraces were upstream from the range bounding fault which formation ages were estimated as 116 64 35 and 10 ka bp according to optically stimulated luminescence osl dating combined with previous 14 c and osl ages the correlation between time of the terraces formation and climatic fluctuations recorded in a guliya ice core reveals that alluvial fan aggradation was concentrated during the cold stages and that incision occurred during the succeeding cold to warm transitions a majority of alluvial fan terraces developed in accelerated uplift since 64 ka which indicates that tectonic uplift provided the driving force for continuous downcutting after climatic change triggered it geomorphic indices channel gradient and v distribution reconstructs the model of discrepant uplift in the langshan range with the fastest uplift rate in the central part which is controlled by range bounding faults

observations on the role of lithology in strath terrace formation and bedrock channel width field observations from western washington and eastern tibet indicate a strong lithologic influence on strath terrace formation and highlight the response of bedrock channel width to spatial gradients in bedrock erodibility and or rock uplift rates measurements of local bedrock bed and bank erosion rates together with observations of the role of weathering processes on erosion of siltstones and sandstones illustrate a mechanism that underlies a conceptual model that predicts a strong lithological control on strath terrace formation direct measurements of bedrock erosion rates in lithologies susceptible to accelerated erosion upon sub aerial exposure show that lateral rates of bedrock bank erosion can substantially exceed vertical incision below the perennial flow level due to an asymmetry in erodibility between perennially submerged rock and rock exposed to cyclic wetting and drying on bedrock channel walls under such conditions the rapid weathering mediated lowering of bedrock exposed above baseflow promotes development of a beveled bedrock platform that could become a strath terrace upon abandonment in contrast to previous studies channel widths measured across a substantial gradient in lithology slope and long term erosion rates in eastern tibet do not follow conventional relations where channel width scales as a power law function of drainage area instead as they flow across a zone of rapid uplift these channels systematically narrow relative to the predicted width extrapolated from traditional power law relations field studies from a wide range of geological settings and lithologies support the interpretation that in general strath terraces tend to be more extensive in rivers flowing over weak sedimentary rock and tend to be poorly developed and or preserved where rivers flow over hard erosion resistant rock

timing and significance of the initiation of present day deserts in the northeastern hexi corridor china abstract the tengger desert and badain jaran desert are two typical deserts in the northwest arid area of china naac located near the margin of the monsoonal region through chronological research of the oldest loess sections formed from synchronous deposition of the desert dusts we suggest that the initial present day tengger and badain jaran deserts appeared no later than about 0 85 ma because this timing of present day desert initiation in the eastern part of the naac is very similar to the other two deserts in the west we suggest that the naac formed at approximately 0 85 ma the uplifting of the tibetan plateau accelerated at around 0 85 ma an event that caused the plateau to enter the cryosphere this resulted in remarkable enhancement of the winter monsoon as well as bifurcation of the mid lower westerlies this is the most fundamental factor that affected the formation of the naac

using in situ produced cosmogenic isotopes to estimate rates of landscape evolution a review from the geomorphic perspective the application of in situ produced cosmogenic isotopes to problems in geomorphology has increased rapidly over the past decade at least 57 papers and numerous abstracts have been published since the mid 1980s when the first mass spectrometric measurements of terrestrially produced cosmogenic isotopes were made taken at face value these studies provide quantitative information about rates of landscape evolution and landform age however the significance of calculated erosion rates and exposure ages depends strongly on the models used to interpret isotopic data the validity of assumptions inherent to these models and the geologic surroundings in which the samples were collected this paper attempts to place cosmogenic isotope studies in a geomorphic context by reviewing fundamentals of the method and evaluating the validity of assumptions under which these data have been interpreted at present the establishment of high precision cosmogenically based glacial and alluvial chronologies is stymied by the evolution of geomorphic surfaces the erosion of rock from sampled boulders the potential for isotope inheritance from previous exposure and the uncertainty of isotopic measurements uncertainties in isotope production rates and the observed variability of exposure ages on individual geomorphic surfaces limit the confidence with which cosmogenic ages can be correlated reliably with those obtained by other techniques estimation of erosion rates at single points on the landscape gives useful small scale information extrapolation of these rates over longer time and larger spatial scales is less sure and most likely biased toward lower erosion rates by die inadvertent selection of resistant sample sites however because erosion rates are so poorly constrained at present even estimates to within a factor of 2 may be of significant value to geomorphologists and tectonicists

impact of tectonics on alluvial landforms in the hexi corridor northwest china abstract the hexi corridor is a cenozoic foreland basin system on the northeast margin of the qinghai tibet plateau the structure is characterised by reverse faults trending nnw or wnw rivers have been affected by sinistral offset by wnw trending faults and dextral offset by nnw trending faults the cenozoic sinistral offset reaches 24 km on the north front fault trending wnw of the qilian mountains on the northeast front fault trending nnw of the yumu mountains a bluff of the hei river terrace has been dextrally offset by 12 m with a rate of 1 2 m ka the vertical movement of the faults has caused the deformation of river terraces and controlled the distribution and migration of the alluvial fans three terraces of the hei river have been vertically dislocated 9 m 4 m and 2 m respectively by a reverse fault with uplift rates of 0 4 1 7 m ka two reverse faults have caused the older alluvial fans to be dissected and the younger fans to be deposited more towards the centre of the jiuquan basin the dislocation of terraces and the migration of alluvial fans suggests that tectonic activity was more intense around 160 and 40 ka bp

along strike growth of the ostler fault new zealand consequences for drainage deflection above active thrusts 1 rarely are geologic records available to constrain the spatial and temporal evolution of thrust fault growth as slip accumulates during repeated earthquake events here we utilize multiple generations of dated and deformed fluvial terraces to explore two key aspects of the along strike kinematic development of the ostler fault zone in southern new zealand over the past 100 k y accumulation of fault slip through space and time and fixed length thrust growth that results in patterns of drainage diversion suggestive of laterally propagating faults along the ostler fault surface deformation patterns revealed by topographic surveying of terrace profiles in nine transverse drainages define systematic variations in fault geometry and suggest deformation over both listric and planar thrust ramps kinematic modeling of folded terrace profiles and 100 fault scarp surveys along major fault sections reveals remarkably similar slip distributions for multiple successions of geomorphic surfaces spanning 100 k y spatially abrupt and temporally sustained displacement gradients across zones of fault section overlap suggest that either persistent barriers to fault propagation or interference between overlapping faults dominate the interactions of fault tips from the scale of individual scarps to the entire fault zone deformed terrace surfaces dated using optically stimulated luminescence and cosmogenic radionuclides indicate steady maximum rates of fault slip of 1 9 mm yr during the late quaternary slip data synthesized along the central ostler fault zone imply that displacement accumulated at approximately constant fault lengths over the past 100 k y a northward temporal progression of abandoned wind gaps along this section thus reflects lateral tilting in response to amplification of displacement rather than simple fault lengthening or lateral propagation oscillations of climate at 104 yr time scales modulate the formation and incision of geomorphic surfaces during successive glacial stages superimposed on apparently steadier rates of fault slip such climate dependent surfaces contribute to a pattern of progressive drainage deflection along the central ostler fault zone that is largely independent of fault propagation

numerical modeling of fluvial strath terrace formation in response to oscillating climate many river systems in western north america retain a fluvial strath terrace rec ord of discontinuous downcutting into bedrock through the quaternary their importance lies in their use to interpret climatic events in the headwaters and to determine long term incision rates terrace formation has been ascribed to changes in sediment supply and or water discharge produced by late quaternary climatic fluctuations we use a one dimensional channel evolution model to explore whether temporal variations in sediment and water discharge can generate terrace sequences the model includes sediment transport vertical bedrock erosion limited by alluvial cover and lateral valley wall erosion we set limits on our modeling by using data collected from the terraced wind river basin two types of experiments were performed constant period sinusoidal input histories and variable period inputs scaled by the marine 18 o rec ord our simulations indicate that strath terrace formation requires input variability that produces a changing ratio of vertical to lateral erosion rates straths are cut when the channel floor is protected from erosion by sediment and are abandoned and terraces formed when incision can resume following sediment cover thinning high sediment supply promotes wide valley floors that are abandoned as sediment supply decreases in contrast wide valleys are promoted by low effective water discharge and are abandoned as discharge increases widening of the valley floors that become terraces occurs over many thousands of years the transition from valley widening to downcutting and terrace creation occurs in response to subtle input changes affecting local divergence of sediment transport capacity formation of terraces lags by several thousand years the input changes that cause their formation our results suggest that use of terrace ages to set limits on the timing of a specific event must be done with the knowledge that the system can take thousands of years to respond to a perturbation the incision rate calculated in the field from the lowest terrace in these systems will likely be higher than the rate calculated by using older terraces because the most recent fluvial response in the field is commonly downcutting associated with declining sediment input since the last glacial maximum this apparent increase in incision rates is observed in many river systems and should not necessarily be interpreted as a response to an increase in rock uplift rate

quantifying periglacial erosion insights on a glacial sediment budget matanuska glacier alaska glacial erosion rates are estimated to be among the highest in the world few studies have attempted however to quantify the flux of sediment from the periglacial landscape to a glacier here erosion rates from the nonglacial landscape above the matanuska glacier alaska are presented and compare with an 8 yr record of proglacial suspended sediment yield non glacial lowering rates range from 1 8 0 5 mm yr 1 to 8 5 3 4 mm yr 1 from estimates of rock fall and debris flow fan volumes an average erosion rate of 0 08 0 04 mm yr 1 from eight convex up ridge crests was determined using in situ produced cosmogenic 10be extrapolating these rates based on landscape morphometry to the matanuska basin 58 ice cover it was found that nonglacial processes account for an annual sediment flux of 2 3 1 0 106 t suspended sediment data for 8 years and an assumed bedload to estimate the annual sediment yield at the matanuska terminus to be 2 9 1 0 106 t corresponding to an erosion rate of 1 8 0 6 mm yr 1 nonglacial sources therefore account for 80 45 of the proglacial yield a similar set of analyses were used for a small tributary sub basin 32 ice cover to determine an erosion rate of 12 1 6 9 mm yr 1 based on proglacial sediment yield with the nonglacial sediment flux equal to 10 7 of the proglacial yield it is suggested that erosion rates by nonglacial processes are similar to inferred subglacial rates such that the ice free regions of a glaciated landscape contribute significantly to the glacial sediment budget the similar magnitude of nonglacial and glacial rates implies that partially glaciated landscapes will respond rapidly to changes in climate and base level through a rapid nonglacial response to glacially driven incision copyright 2009 john wiley sons ltd

constructing a stacked benthic δ18o record composite stacks were constructed by superimposing 6 to 13 benthic foraminiferal 1 8 o records covering the period 0 850 ka an initial timescale for each core was established using radioisotopic age control points and assuming constant sedimentation rates between these points the average of these records is our 13 core untuned stack next we matched the 41 kyr component of each record individually to variations in earth s obliquity four of the 13 records produced timescales that were inconsistent with one or more of the known radioisotopic ages the nine remaining cores were averaged to create a minimally tuned stack six of the minimally tuned cores were assembled into a tropical stack for each stack we estimated the uncertainty envelope from the standard deviation of the constituents spectral analysis of the three stacks indicates that benthic 1 8 o is dominated by a 100 kyr oscillation that has a narrow spectral peak the contribution of precession to the total variance is small when compared to prior results from planktic stacks

late cenozoic climate change paces landscape adjustments to yukon river capture late cenozoic cooling and changes in glacial interglacial cycle tempo are thought to increase global rates of erosion starting 3 million years ago ma bedrock rivers set rates and patterns of erosion in most landscapes but constraints on river response to late cenozoic climate change remain elusive here we determine cosmogenic isotope and luminescence ages of well preserved bedrock terraces along the fortymile river yukon river basin to reconstruct an 5 myr history of fluvial adjustment to late cenozoic climate and yukon river headwater capture at 2 6 ma post capture yukon river downcutting lowered the fortymile river outlet forcing subsequent bedrock incision throughout the fortymile basin in two pulses from 2 4 to 1 8 ma and at 1 ma these pulses of incision disrupted longer intervals of slow river channel sedimentation under near consistent climate forcing from 4 8 to 2 4 ma and from 1 8 to 1 ma the fortymile river delivers sediment to the bering sea where provenance and accumulation rate changes since 4 3 ma match observed variations in incision our results link alluviation and incision to late cenozoic climate steadiness and change respectively and support the hypothesis that climate forced changes in precipitation and runoff fundamentally control the pace of river incision and landscape erosion increased river incision and landscape erosion can be attributed to late cenozoic cooling changes in hydroclimate according to cosmogenic isotope and luminescence ages of a sequence of bedrock terraces in the yukon river basin

dating faulted alluvial fans with cosmogenic 10be in the gurvan bogd mountain range gobi altay mongolia climatic and tectonic implications the gurvan bogd mountain range is a fault system characterized by strong earthquakes m 8 separated by long periods of quiescence further to the previous works in the area our study provides new data concerning the tectonic and climatic processes in the gobi altay to quantify the slip rates along the faults we dated offset alluvial fans analysing the in situ produced 10 be along profiles at depth the slip rates along the bogd strike slip fault and its associated thrust faults over the upper pleistocene holocene period are 0 95 0 29 mm yr 1 and comprised between 0 12 0 02 and 0 13 0 02 mm yr 1 respectively the surfaces ages account for a cyclic formation of the fans over the past 360 ka in correlation with the terminations of the marine isotope stages 2 6 8 and 10

rapid incision of the mekong river in the middle miocene linked to monsoonal precipitation the uplift of orogenic plateaus has been assumed to be coincident with the fluvial incision of the gorges that commonly cut plateau margins the mekong river which drains the eastern qiangtang terrane and southeastern tibetan plateau is one of the ten largest rivers in the world by water and sediment discharge when the mekong river was established remains highly debated with estimates that range from more than 55 to less than 5 million years ago despite being a key constraint on the elevation history of the tibetan plateau here we report low temperature thermochronology data from river bedrock samples that reveal a phase of rapid downward incision 700 m of the mekong river during the middle miocene about 17 million years ago long after the uplift of the central and southeastern tibetan plateau however this coincides with a period of enhanced east asian summer monsoon precipitation over the region compared with the early miocene using stream profile modelling we demonstrate that such an increase in precipitation could have produced the observed incision in the mekong river in the absence of an obvious tectonic contribution we suggest that the rapid incision of the tibetan plateau and the establishment of the mekong river in the middle miocene may be attributed to increased erosion during a period of high monsoon precipitation incision of the mekong river that occurred after the uplift of the tibetan plateau may have been driven by a period of high monsoon precipitation as suggested by age data from river bedrock samples and stream profile modelling

the processes and mechanisms of severe sandstorm development in the eastern hexi corridor china during the last glacial period abstract dust transported by sandstorms has been an important feedback in climate change in the past and its environmental effects are predicted to have a great impact on future global climatic change investigating the grain size classes and the standard deviations of the modern sandstorm samples and the samples in the shagou section situated in the eastern hexi corridor lead us to suggest that the sand fraction within the range of 275 4 550 m in this section can be used as a sensitive indicator of severe sandstorms we selected the size range in the l1 stratum of the shagou loess section as indicative of temporal changes in sandstorm intensity in the eastern hexi corridor and found that during the last glacial period severe sandstorms in the eastern hexi corridor occurred with high frequency during these periods i 70 54 ka b p ii 51 48 ka b p iii 45 42 ka b p iv 38 33 ka b p v 31 28 ka b p and vi 26 12 ka b p in general the frequency and intensity of dust storms in the early mis 4 and late mis 2 periods were both high but they were reduced in the middle period mis 3 the primary factors controlling severe sandstorms are hydrology and wind power followed by the expansion of the source extent reduced precipitation caused the source region of sandstorms to expand in addition wind speeds also increased at this time these factors may have directly contributed to the abundance of severe sandstorms based on the grain size from a loess section the shagou section in the eastern hexi corridor we propose an evolutionary sequence of the severe sandstorms during the last glacial period this sequence is consistent with the dust records in the arctic the antarctic and low latitude the central equatorial pacific areas thus globally synchronous periods of high dust activity occurred in the last glacial period the strong winds proposed here provide a potential explanation for the global consistency of dust flux changes during the last glacial period

variations of lateral bedrock erosion rates control planation of uplifting folds in the foreland of the tian shan nw china fluvial planation surfaces such as straths commonly serve as recorders of climatic and tectonic changes and are formed by the lateral erosion of rivers a process that remains poorly understood here we present a study of kilometer wide fluvially eroded low relief surfaces on rapidly uplifting folds in the foreland of the southwestern tian shan a combination of field work digital elevation model analysis and dating of fluvial deposits reveals that despite an arid climate and rapid average rock uplift rates of 1 3 mm yr rivers cut extensive 1 2 km wide surfaces with typical height variations of 2 6 kyr the extent of this beveling varies in space and time such that different beveling episodes affect individual structures between times of planation beveled surfaces are abandoned incised and deformed across the folds in a challenge to models that link strath cutting and abandonment primarily to changes in river incision rates we demonstrate that lateral erosion rates of antecedent streams crossing the folds have to vary by more than 1 order of magnitude to explain the creation of beveled platforms in the past and their incision at the present day these variations do not appear to covary with climate variability and might be caused by relatively small much less than an order of magnitude changes in sediment or water fluxes it remains uncertain in which settings variations in lateral bedrock erosion rates predominate over changes in vertical erosion rates therefore when studying fluvial planation and strath terraces variability of both lateral and vertical erosion rates should be considered

the linking of the upper middle and lower reaches of the yellow river as a result of fluvial entrenchment abstract the upper middle yellow river flows through the fenwei graben a structure resulting from extensional tectonism that was formed and repeatedly extended during the cenozoic the drainage system within this graben was formerly isolated from the lower reaches of the yellow river system by the xiaoshan mountains an actively growing nw se trending range the modern course of the yellow river takes it through this range along the sanmen gorge the formation of which was of great significance in that it initiated through going drainage between the upper middle and lower reaches of the system the timing of this event which was clearly a critical point in the evolution of the yellow river can be established by dating the terraces in the gorge intermittent deepening of this gorge by the yellow river from a high level planation surface capping the mountain range has resulted in the formation of five terraces magnetostratigraphic records from aeolian deposits accumulated on these surfaces provide a geochronological sequence for this geomorphic archive in which the ages of the planation surface and of terraces t5 t4 t3 t2 and t1 have been determined as 3 63 ma 1 24 ma 0 86 ma 0 62 ma 129 ka and 12 ka respectively under the constraint of this chronological framework a model for landscape evolution is proposed here uplift of the inner fenwei graben and of the surrounding mountain ranges led to dissection of the 3 63 ma old planation surface in conjunction with the formation of the sanmen gorge drainage of the lake previously occupying the basin would have promoted incision into the fluvio lacustrine graben sediments indeed gorge formation through the xiaoshan may have been initiated or intensified by lake overflow the ages obtained for the planation surface and uppermost terrace suggest that the formation of the sanmen gorge and the initiation of the through going eastward drainage of the yellow river occurred between 3 63 and 1 24 ma before the start of gorge entrenchment the products of erosion in the modern upper catchment of the yellow river were unable to reach the sea the dramatic increase in deposition rates in the bohai gulf at the mouth of the modern yellow river in the east china sea 1 0 ma ago thus resulted from the initiation of an integral enlarged yellow river catchment drainage through the sanmen gorge it does not imply an increase in erosion rates at that time

multi phased uplift of the southern margin of the central anatolian plateau turkey a record of tectonic and upper mantle processes abstract uplifted neogene marine sediments and quaternary fluvial terraces in the mut basin southern turkey reveal a detailed history of surface uplift along the southern margin of the central anatolian plateau from the late miocene to the present new surface exposure ages 10be 26al and 21ne of gravels capping fluvial strath terraces located between 28 and 135 m above the goksu river in the mut basin yield ages ranging from ca 25 to 130 ka corresponding to an average incision rate of 0 52 to 0 67 mm yr published biostratigraphic data combined with new interpretations of the fossil assemblages from uplifted marine sediments reveal average uplift rates of 0 25 to 0 37 mm yr since late miocene time starting between 8 and 5 45 ma and 0 72 to 0 74 mm yr after 1 66 to 1 62 ma together with the terrace abandonment ages the data imply 0 6 to 0 7 mm yr uplift rates from 1 6 ma to the present the different post late miocene and post 1 6 ma uplift rates can imply increasing uplift rates through time or multi phased uplift with slow uplift or subsidence in between longitudinal profiles of rivers in the upper catchment of the mut and ermenek basins show no apparent lithologic or fault control on some knickpoints that occur at 1 2 to 1 5 km elevation implying a transient response to a change in uplift rates projections of graded upper relict channel segments to the modern outlet together with constraints from uplifted marine sediments show that a slower incision uplift rate of 0 1 to 0 2 mm yr preceded the 0 7 mm yr uplift rate the river morphology and profile projections therefore reflect multi phased uplift of the plateau margin rather than steadily increasing uplift rates multi phased uplift can be explained by lithospheric slab break off and possibly also the arrival of the eratosthenes seamount at the collision zone south of cyprus

formation and evolution of the badain jaran desert north china as revealed by a drill core from the desert centre and by geological survey abstract the deserts in north china are regarded as direct records of the process of inland asian aridification amongst these deserts those proximal to the chinese loess plateau clp are especially important because of their role as sediment source areas in order to investigate the formation history of the badain jaran desert the largest desert proximal to the clp a 310 m long drill core was obtained from the desert centre which reached the underlying basement rock the lithology of the core consists of an upper layer of aeolian sand with three intercalated layers of lacustrine sediments overlying alluvial fluvial deposits which are developed unconformably over red coloured basement rock a geological survey indicates that the lower red coloured basement rock is of late cretaceous age and is cut by a mesozoic erosion surface widely developed over the badain jaran area on the basis of optically stimulated luminescence and electron spin resonance dating and stratigraphic correlation a preliminary chronological framework was established which was improved by tuning the aeolian sand proportion of the drill core to earth orbital obliquity and precession this final chronology suggests that 1 the basal age of the desert strata is at least 1100 ka corresponding to the formation of the badain jaran desert and 2 that the formation of the erosion surface terminated and the surface had begun to subside by at least 1200 ka the formation of the desert can be summarized as follows the alluvial fluvial fan formed by the heihe river draining the qilian mountains provided sufficient sedimentary material to form the desert under an arid climate while the asian winter monsoon and the westerlies entrained the clastic sediments from the fan area which finally accumulated downwind more distant sediment transport was prevented by the intervening mountainous terrain these coupled processes were driven by tibetan plateau uplift and ongoing global climatic cooling after initial formation of the desert three humid phases occurred in mis 13 15 mis 5 and the holocene during which extensive lakes developed the sequential drying out of the lakes may reflect inter relationships between global climate and the intensity of the asian summer monsoon and the westerlies

incision rate of the yellow river in northeastern tibet constrained by 10be and 26al cosmogenic isotope dating of fluvial terraces implications for catchment evolution and plateau building unlike other large rivers flowing out of tibet the yellow river escapes from the plateau towards the ne crossing no less than five nw se striking actively growing ranges and intervening basins thick plio quaternary deposits and fluvial terraces testify to a phase of aggra dation and sediment infill up to the average surface elevation 3200 3250 m a s l of the gonghe guide and qinghai lake basins a set of seven main terraces across the gonghe basin suggests progressive down cutting of the yellow river carving the 500 m deep longyang gorge at the basin exit 10be and 26al concentrations in quartz of surface and sub surface samples of four terraces constrain the timing of incision by determining the burial age of the deposit and the exposure age of its surface modelling the depth dependence of the 10be concentration and the 26al 10be ratio allows us to constrain the onset of the ongoing phase of incision to 120 250 ka these ages suggest long term incision rates between 2 6 mm a together with the present morphology of the yellow river terraces across the gonghe basin and the longyang gorge our results imply rapid river catchment evolution and interaction between river dynamics tectonic and climate in northeastern tibet

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

rates and kinematics of active shortening along the eastern qilian shan china inferred from deformed fluvial terraces in the eastern qilian shan a flight of fluvial terraces developed along the jinta river valley are deformed across the nanying anticline four individual fluvial terraces are preserved at different elevations above the river and higher terrace treads are draped by systematically thicker aeolian loess optically stimulated luminescence dating of deposits at the base of the loess provides constraints on the timing of surface abandonment terraces were abandoned at 69 4 ka b p t4 57 4 ka b p t3 and between 34 3 ka b p t2 respectively differential gps measurement of the terrace profile across the anticline allows reconstruction of subsurface fault geometry we model terrace deformation above a listric thrust fault with a tip line at 2 2 0 1 km depth and whose dip shallows systematically to 23 3 degrees at depth of 5 8 1 1 km combining terrace ages with this model of fault geometry we estimate a shortening rate of 0 8 0 2 mm a across the nanying fold and a shortening rate of similar to 0 1 mm a across the mountain front fault since similar to 70 ka b p this rate suggests that the frontal fault system along the eastern qilian shan accomplishes crustal shortening at rates of approximately 0 9 0 3 mm a during late pleistocene time

paleocurrent and fabric analyses of the imbricated fluvial gravel deposits in huangshui valley the northeastern tibetan plateau china abstract gravel deposits on fluvial terraces contain a wealth of information about the paleofluvial system in this study flow direction and provenance were determined by systematic counts of more than 2000 clasts of imbricated gravel deposits in the xining region northeastern tibetan plateau china these gravel deposits range in age from the modern huangshui riverbed to miocene aged deposits overlain by eolian sediments our major objectives were not only to collect first hand field data on the fluvial gravel sediments of the xining region but also to the reconstruct the evolution of the fluvial system these data may offer valuable information about uplift of the northeastern tibetan plateau during the late cenozoic era reconstructed flow directions of the higher and lower gravel deposits imply that the river underwent a flow reversal of approximately 130 180 in addition the lithological compositions in the higher gravel deposits differ significantly from the lower terraces suggesting that the source areas changed at the same time eolian stratigraphy overlying the gravel deposits and paleomagnetic age determination indicate that this change occurred sometime between 1 55 ma and 1 2 ma we suggest that tectonic activity could explain the dramatic changes in flow direction and lithological composition during this time period therefore this study provides a new scenario of fluvial response to tectonic uplift a reversal of flow direction in addition field observation and statistical analyses reveal a strong relationship between rock type size and roundness of clasts

fluvial terrace formation in the eastern fenwei basin china during the past 1 2 ma as a combined archive of tectonics and climate change abstract the key to understanding the fluvial response to climate change and surface uplift is a thorough distinguishing between their roles in terrace formation previous studies have tended to attribute the fluvial behavior of deposit incision alternation to climate cyclicity a preliminary explanation is proposed here for terrace formation in the eastern part of the fenwei basin china the observed fluvial terrace sequence was developed by the yellow river deeply downcutting into the emei platform which was uplifted within the eastern fenwei basin and therefore it probably records the tectonic history of this platform on the basis of the magnetostratigraphy and optically stimulated luminescence osl dating a ca 1 2 ma chronology was established for this terrace sequence pedostratigraphic analysis of the loess deposits accumulated on each tread reveals that the terrace deposits are overlain immediately by a paleosol bed suggesting that the abandonment of these terraces due to fluvial incision occurred at the transitions from glacial to interglacial climates the glacial interglacial climate cycle probably has a temporal control on the fluvial behavior of deposit incision alternation even though the yellow river develops in the subsiding fenwei basin the terrace generation may be sporadic and in the form of unusual stacked pattern before the emei platform was uplifted within the eastern fenwei basin the terrace staircases however formed in synchrony with glacial interglacial climate cycles since this platform began to uplift in the late middle pleistocene this result indicates that uplift may be necessary in large terrace staircase genesis it can force the river system to downcut deeply enough during climatic transitions to separate terrace levels adequately favoring the generation and subsequent preservation of the terrace treads the terrace sequence of the yellow river in the eastern fenwei basin therefore can be considered as a combined archive of climate change and local tectonic activity

post tectonic landscape evolution in ne iberia using staircase terraces combined effects of uplift and climate river incision into bedrock resulting from the combined effects of tectonic uplift and climate governs long term regional landscape evolution we determined spatial and temporal patterns of post orogenic stream incision from a sequence of well preserved staircase terraces developed over the last 1 ma in the central pyrenees and its southern foreland ebro basin ne spain extensive remnants of ten vertically separated terraces qt1 to qt10 from oldest to youngest were mapped along 170 km of the cinca river valley transverse to the pyrenean mountain belt multiple outcrops appear in the upper reach of the valley ainsa sector 50 km from headwaters as well as in the lower reach albalate sector 125 km from headwaters fluvial incision into bedrock was calculated using i differentially corrected gps measurements of the altitude of straths and ii numerical dating of alluvial sediments from the lower terraces qt5 to qt9 by optically stimulated luminescence previously reported by lewis et al 2009 and supplemented with new dates for the upper terraces qt1 qt2 and qt3 based on paleomagnetism and supported by soil development considering altitude differences and the elapsed time between successive well preserved terrace couples qt3 qt7 qt7 qt9 and qt9 active channel mean bedrock incision rates ranged from 0 76 to 0 38 m ka 1 at the upper reach of the valley ainsa section and from 0 61 to 0 20 m ka 1 at the lower reach albalate section river incision along the valley produced vertically separated near parallel longitudinal terrace profiles evidencing a rapid near uniform regional uplift as response to i the tectonic lithospheric thickening in ne iberia and ii the erosional download rebound related to the ebro basin exorheism moreover a subtle upstream divergence of strath profiles may have been a consequence of an increase in uplift rate toward the head of the valley additionally incision rates changed over time as indicate results from the lower reach albalate section the maximum rate was 1 48 m ka 1 between qt7 61 ka and qt8 47 ka and the minimum rate was 0 11 m ka 1 between qt3 401 ka and qt5 178 ka the highest incision rates were produced after the marine isotope stage 4 most likely in response to i an increased snowmelt discharge during the subsequent deglaciation related to the last maximum advance of glaciers in the southern pyrenees and ii a limited width of the valley after qt7 formation resulting from the deactivation of the westward river migration therefore incision rates over the last 1 ma in the cinca river valley were basically controlled by near uniform bedrock uplift in the context of climate variability the results reported in this study represent significant data on fluvial incision in ne iberia and provide an assessment of the regional post tectonic landscape evolution

persistent rupture terminations at a restraining bend from slip rates on the eastern altyn tagh fault abstract restraining double bends along strike slip faults inhibit or permit throughgoing ruptures depending on bend angle length and prior rupture history modeling predicts that for mature strike slip faults in a regional stress regime characterized by simple shear a restraining bend of 18 and 4 km length impedes propagating rupture indeed natural evidence shows that the most recent rupture s of the xorkoli section 90 93 e of the eastern altyn tagh fault atf ended at large restraining bends however when multiple seismic cycles are considered in numerical dynamic rupture modeling heterogeneous residual stresses enable some ruptures to propagate further modulating whether the bends persistently serve as barriers these models remain to be tested using observations of the cumulative effects of multiple earthquake ruptures here we investigate whether a large restraining double bend on the atf serves consistently as a barrier to rupture by measuring long term slip rates around the terminus of its most recent surface rupture at the aksay bend our results show a w e decline in slip as the satf enters the bend as would be predicted from repeated rupture terminations there prior work demonstrated no holocene slip on the central most misoriented portion of the bend while 19 79 m offsets suggest that multiple ruptures have occurred on the west side of the bend during the holocene thus we conclude the gradient in the satf s slip rate results from the repeated termination of earthquake ruptures there however a finite slip rate east of the bend represents the transmission of some slip suggesting that a small fraction of ruptures may fully traverse or jump the double bend this agreement between natural observations of slip accumulation and multi cycle models of fault rupture enables us to translate observed slip rates into insight about the dynamic rupture process of individual earthquakes as they encounter geometric complexities along faults

interaction between regional and local tectonic forcing along a complex quaternary extensional basin upper tiber valley northern apennines italy abstract in extending areas undergoing regional tectonic uplift the persistence of subsidence at a normal fault hanging wall depends on the competition between regional and local tectonic effects when regional uplift exceeds the subsidence of the hanging wall block denudation prevails at both the hanging wall and the foot wall when local tectonic subsidence exceeds regional uplift sedimentation occurs over the hanging wall block supplied by foot wall erosion we analyzed a pliocene quaternary continental basin currently crossed by the tiber river in italy the tectono sedimentary evolution of the basin developed at the hanging wall of a regional low angle extensional detachment the alto tiberina fault in the axial region of the northern apennines of italy this area is affected by regional uplift on the order of 0 5 1 0 mm yr the present day activity of the fault is revealed by both microseismicity and geodetic gps data we investigated the mid 10 100 ka and long term 0 5 3 0 ma evolution of the three depocenters by studying the continental pleistocene succession infilling the basin as well as fluvial terraces and higher paleosurfaces carved into the pleistocene deposits by using surficial geologic data and an interpretation of a set of seismic reflection profiles we show that the three depocenters experienced a fairly similar evolution during the pliocene early pleistocene when a 1000 m thick continental succession was deposited on the contrary geomorphological observations indicate that at the beginning of the middle pleistocene a switch occurred in the evolution of the three depocenters in the northernmost sansepolcro sub basin bounding normal faults are active and hanging wall subsidence outpaces regional uplift concurrently in the umbertide and ponte pattoli sub basins uplift dominates over the hanging wall subsidence promoting river incision and exhumation of the pleistocene deposits for these two depocenters by means of terrace river correlations we estimate that the incision rate is 0 3 0 35 mm yr suggesting a maximum tectonic subsidence of 0 2 mm yr the identification of a heterogeneous uplift pattern along the hanging wall of the alto tiberina fault driven by different displacement rates of its fault splays allowed us to characterize fault segments with different activities and possibly different seismic behaviors

correlation of fluvial terraces within the hikurangi margin new zealand implications for climate and baselevel controls abstract a correlation of fluvial terraces is presented for eight non glacial catchments of the eastern north island new zealand within the actively uplifting hikurangi margin using a combination of loess and tephra coverbed stratigraphy and radiocarbon and osl dating of fluvial deposits and loess coverbeds we demonstrate correlation of four fill terraces t1 t4 the available age constraints suggest t1 15 30 ka t2 31 50 ka t3 50 70 ka and t4 115 ka but the association and temporal link with loess deposits suggest correlation with cold periods and thus the refinement of t2 late mis 3 31 40 ka t3 mis 4 55 70 ka t4 mi substage 5b 90 ka 5d 110 ka or mis 6 140 160 ka the ability to correlate terraces between catchments plus the lack of independent evidence for tectonic triggering events indicates terraces have probably formed in response to either climate terrestrial or baselevel sea level control climate control is indicated by the temporal link of post glacial incision with re establishment of forest cover and of lgm aggradation with limited grass and shrub cover and periglacial processes aggradation due to increased sediment supply under reduced vegetation is dramatically demonstrated by formation of the taupo pumice alluvium terrace in response to inundation by volcanic deposits unwelded ignimbrite following the 1 8 ka taupo eruption and the response to post settlement

climate driven formation of fluvial terraces across the tibetan plateau since 200 kya a review abstract the causes of terrace formation in active orogenic belts have long been studied here we present a synthesis of 147 available papers on the ages of quaternary terraces within the tibetan plateau and along the surrounding orogenic belts more than 1500 ages were collected to establish a database for exploring the causes of fluvial terrace formation because the age data were collected from different settings ages younger than 200 ka were grouped into three regional climate systems the westerlies indian summer monsoon and east asian summer monsoon we further examined the relationship between terrace formation and climate change as well as the contribution of tectonic uplift our results indicate that the intervals of fluvial terrace formation are synchronous with transitions in global climate from cooler to warmer conditions stadials to interstadials we propose that the formation of fluvial terraces across the tibetan plateau has been controlled mainly by cyclical climate changes although there is not a one to one correspondence

explicit treatment of inheritance in dating depositional surfaces using in situ 10be and 26al we describe a new strategy for dating depositional landscape surfaces using in situ produced cosmogenic radionuclides crns that removes the complication of nuclide inheritance by clasts prior to depositon two amalgamated samples each consisting of 30 clasts one from the surface and one from a fixed depth in the subsurface constrain this crn inheritance and date the surface the inheritance may be used to estimate minimum exhumation rates and maximum transport times within the geomorphic system we test the technique using sup 10 be and sup 26 al to date the third fr3 of five terraces along the fremont river utah and the third wr3 of 15 along the wind river wyoming whereas effective ages based solely upon the surface samples yield 118 138 ka fr3 and 93 ka wr3 the subsurface samples reveal that inheritance accounts for 22 wr3 to 43 fr3 of the total crn concentration taking this into account yeilds terrace ages of nearly 61 81 ka for fr3 and nearly 67 76 ka for wr3 we explore the dependence of age estimates on the accumulation history of the terrace silt caps 22 refs 3 figs 1 tab

quaternary paleoenvironmental evolution of the tengger desert and its implications for the provenance of the loess of the chinese loess plateau abstract the dust sources of the loess deposits of the chinese loess plateau clp are suggested to be the gobi deserts in north china and the tibetan plateau in southwest china the tengger desert td a major desert situated to the northeast of the tibetan plateau and to the northwest of the clp on the western margin of the present day asian summer monsoon domain is an ideal area for assessing which of these potential dust source areas may be dominant a 104 m long drill core bj14 was obtained from the northwestern td the magnetostratigraphy constrained by electron spin resonance dating in the upper part of the core includes the brunhes matuyama and beginning of the gauss polarity chrons with their boundaries at the depths of 44 57 m and 94 31 m respectively sedimentary facies analysis based on lithological grain size magnetic susceptibility and micropaleontological evidences indicates that the core is primarily composed of lacustrine deposits combined with the results of previous studies in the eastern td and the adjacent regions the sedimentary sequence of core bj14 indicates that lakes occupied the northern and eastern td during most of the early pleistocene and that the onset of a desert environment occurred at 0 9 ma our results suggest that the td may have contributed only a limited amount of dust to the clp during the early pleistocene

impulsive alluviation during early holocene strengthened monsoons central nepal himalaya the steep walled bedrock gorges of the greater himalayan rivers currently lack significant stored sediment suggesting that fluvial erosion and transport capacity outpace the supply of sediment from adjacent hillsides despite this appearance of sustained downcutting such rivers can become choked with sediments and aggrade during intervals of higher precipitation cosmogenic dating 10 be and 26 al of fluvially carved bedrock surfaces indicates that sediment at least 80 m thick filled the marsyandi river valley in central nepal during a time of strengthened early holocene monsoons despite threefold differences in height 43 124 m above the modern river these fluvial surfaces display strikingly similar cosmogenic exposure ages clustering around 7 6 1 ka we speculate that enhanced monsoonal precipitation increased pore pressure and the frequency of landsliding thereby generating a pulse of hillslope derived sediment that temporarily overwhelmed this alpine fluvial system s transport capacity after the easily liberated material was exhausted ca 7 ka the hillslope flux dropped and the river incised through the aggraded alluvium it concurrently eroded adjacent rock walls thereby removing previously accumulated 10 be and 26 al and resetting the cosmogenic clock in the bedrock unlike previous studies these exposure ages cannot be used to derive river incision rates instead they record a coupled fluvial hillslope response to climate change

survival patterns of macrobenthic marine assemblages during the end permian mass extinction in the western tethys dolomites italy abstract the ecological competition between brachiopods and bivalves is analysed by means of a quantitative palaeoecologic method applied on four assemblages located within a short stratigraphic interval approximately 2 m thick in the lower tesero member of the werfen formation in the southern alps the assemblages originate from the tesero bulla and sass de putia sections the analysed stratigraphic interval uppermost changhsingian in age is located between the early and heaviest phase of the end permian mass extinction which occurred across the bellerophon werfen formational boundary event boundary and the permian triassic boundary chronological boundary when nearly all the permian stenotopic holdovers disappeared these assemblages are characterised by small sized skeletons lilliput effect which represent an adaptive survival strategy in stressed and harsh habitats resulting from the climatic and palaeoceanographic changes connected with the mass extinction the tesero assemblages are dominated by rhynchonelliform brachiopod orbicoelia bed cnt10 or streptorhynchus bed cnt11a which were mostly attached at the top of shallow microbialitic mounds these assemblages are again dominated by permian stenotopic taxa and show a palaeozoic structure the tesero habitat which again permitted the survival of brachiopods represented one of the last refuges in the western tethys on the contrary the bulla bu9 10 and sass de putia wpk13a assemblages are bivalve dominated and thus show an ecologic structure typical of early triassic post extinction marine benthic communities or palaeozoic stressed marine communities the bivalve dominated assemblages proliferated in prevailing muddy siliciclastic substrates with brief episodes of microbial algal growth the most important environmental limiting factors and leading causes of end permian mass extinction are discussed in terms of palaeoautecologic and palaeosynecologic analysis the different taxonomic composition and ecologic structure of the assemblages is related to palaeogeography including water depth and connections with the open sea the brachiopod dominated assemblage exclusive of the tesero section proliferated in microbial carbonate habitats in near shore environments the bivalve dominated assemblages which were more widespread than the brachiopod assemblages in the dolomites and also occurred in other western tethys localities occur in more open and deeper marine environments in the western tethys margins the local distribution of mixed faunas suggests that the extinction of permian stenotopic taxa was caused by the onset of poisonous water on the shelves originating from deep marine environments this extinction pattern appears to be a regional phenomenon and does not seem be applicable on a global scale the extinction events were controlled by a complex network of interactive factors and the survival of faunal elements was probably stochastic

changes in sand fractions of binggou section and the expansion and contraction of the tengger desert during 50 30 ka signs of the evolutionary process are well preserved in the aeolian deposits of desert margins and enable reconstruction of desert expansion and contraction the sand content percentage 63 m of loess in the loess desert transitional zone was used as a proxy indicator for determining the proximity of the desert margin according to the dominant wind direction generally nw se in the northwest chinese loess plateau a transect was projected to observe spatial changes in sedimentological characteristics of aeolian deposits during the last glacial period the transect consists of 12 loess sections starting at shapotou in the transitional region between the loess plateau and the tengger desert and ending at tianshui which is located at the north foot of the western qinling mountains in the southernmost part of the loess plateau it shows the properties of temporal and spatial distribution of the malan loess with reduced sand content from northwest to southeast a linear correlation model of sand content and distance was obtained which was similar to the east of the chinese loess plateau according to this model and on the basis of optically stimulated luminescence osl dating from binggou section a detailed and quantificational expansion and contraction for the tengger desert was established copyright 2006 john wiley sons ltd

geometry and late pleistocene slip rates of the liangdang jiangluo fault in the western qinling mountains nw china abstract two groups of faults striking in different direction nww trending and nee trending within the western qinling mountains play important roles in the tectonic deformation and the transference slip along the east end of the east kunlun fault we investigated the fault geometry and kinematics properties in the area based on the displacements of landforms and optically stimulated luminescence osl dating techniques the late pleistocene slip rates along the liangdang jiangluo fault were determined to be 0 43 0 13 mm a thrust and 0 71 0 18 mm a left lateral strike slip we also investigated some other faults and obtained characteristically low slip rates these slip rates are consistent with decadal gps observations despite previous studies that point to a systematic decrease in the left lateral slip rates from 10 mm a to

onset of asian desertification by 22 myr ago inferred from loess deposits in china the initial desertification in the asian interior is thought to be one of the most prominent climate changes in the northern hemisphere during the cenozoic era1 2 3 4 but the dating of this transition is uncertain partly because desert sediments are usually scattered discontinuous and difficult to date here we report nearly continuous aeolian deposits covering the interval from 22 to 6 2 million years ago on the basis of palaeomagnetic measurements and fossil evidence a total of 231 visually definable aeolian layers occur as brownish loesses interbedded with reddish soils this new evidence indicates that large source areas of aeolian dust and energetic winter monsoon winds to transport the material must have existed in the interior of asia by the early miocene epoch at least 14 million years earlier than previously thought3 5 regional tectonic changes and ongoing global cooling are probable causes of these changes in aridity and circulation in asia

climatic controls on frost cracking and implications for the evolution of bedrock landscapes 1 in mountainous landscapes the role of periglacial processes in producing sediment is poorly defined despite evidence of abundant talus slopes ice growth in rock has long been recognized as an efficient erosion mechanism but the effects have not been readily applied to landscape evolution in response to tectonic and climatic forcing here we quantify how and where ice driven mechanical erosion occurs in cold bedrock dominated landscapes using a simple one dimensional numerical heat flow model in our model ice grows by water migration to colder regions in shallow rock by the reduction in chemical potential associated with intermolecular forces between ice and mineral surfaces a process called segregation ice growth the depth and intensity of frost cracking is primarily dependent on mean annual temperature mat with positive mat sites characterized by intense cracking in the top meter of the rock mass and a maximum frost penetration of 4 m in contrast negative mat areas have less intense cracking that primarily occurs at depths between 50 and 800 cm we compare the depth and intensity of frost cracking predicted by our model with measures of the intensity of frost processes determined in three studies the first measured the timing of rockfall in the canadian rockies niagara escarpment and japanese alps the second analyzed scree deposits in the southern alps new zealand and the third documented rockfall frequency in utah these natural examples show that rockfalls tend to nucleate at elevations that coincide with zones of intense frost cracking predicted by our model as such climatic variations associated with interglacial glacial cycles may impart a significant influence on the denudation of mountainous landscapes

optically stimulated luminescence dating of a moraine and a terrace in laohugou valley western qilian shan northeastern tibet the qilian shan is one of the most important mountain ranges for understanding quaternary glaciation in the northeastern tibetan plateau however its western part is not well studied a moraine and an outwash terrace in the laohugou valley were mapped using geomorpho stratigraphy and dated by optically stimulated luminescence after analyzing the minimum age and central age of coarse and fine grained quartz most of the minimum ages for coarse grains are consistent with geomorpho stratigraphic sequence indicating they are closest to the true ages of the sediments the lateral moraine was initially formed at 20 2 2 6 ka during the last glacial maximum and was modified between 11 6 2 0 and 12 9 1 3 ka in the late glacial the outwash terrace was formed between 10 0 1 7 and 5 5 0 7 ka and coincides with temperature rise in the early holocene and the holocene optimum at its last glacial maximum the palaeo glacier was similar to 13 6 km long with an area of 45 3 km 2 4 3 km longer and 34 larger than the contemporary glacier the reconstructed palaeo glacier equilibrium line altitude ela was 4600 40 m or 140 m lower than the present ela the glacier advance in the laohugou valley was less extensive and ela depression was less than found in the eastern qilian shan during lgm and late glacial suggesting a drier climate during the last glacial c 2013 elsevier ltd and inqua all rights reserved

evaluating the role of climate and tectonics during non steady incision of the yellow river evidence from a 1 24 ma terrace record near lanzhou china abstract the competing roles of bedrock uplift and climatic change in the formation of fluvial terraces remain uncertain most of recent studies have attributed terrace formation to climatic changes and held that even in tectonically active settings climate variations control cycles of terrace planation and abandonment based on field investigations of loess paleosol sequences magnetostratigraphy and optically stimulated luminescence osl dating we develop a new chronology for a spectacular flight of terraces along the yellow river near lanzhou china over past 1 24 ma all the terraces are strikingly similar in that they have several meters of paleosol developed directly above fluvial deposits on the terrace treads suggesting that the abandonment of each terrace due to river incision occurs during the transition from glacial to interglacial climates however the ages of terraces cluster in two relatively short time periods 1 24 0 86 ma and 0 13 ma present during the intervening time between 0 86 ma and 0 13 ma terraces either did not form or were not preserved we suggest that this record indicates that rock uplift rates varied through time and influenced terrace formation preservation thus our results demonstrate the utility of deep chronologic records from fluvial terraces for deconvolving the effects of tectonics and climate on fluvial incision

disequilibrium of holocene sediment yield in glaciated british columbia it is generally supposed that specific sediment yield the quantity of sediment passing a monitored river cross section per unit area drained upstream of that section declines as the area drained increases1 3 part of the sediment mobilized from the land surface is supposed to go back into storage at field edges and on footslopes and floodplains in contrast we show here that data from british columbian rivers reveal a pattern of increasing specific sediment yield at all spatial scales up to 3 104 km2 this results from the dominance of secondary remobilization of quaternary sediments along river valleys over primary denudation of the land surface the result controverts the conventional model which has been derived from studies of small highly disturbed agricultural catch ments the rivers are still responding to the last glaciation giving a landscape relaxation time greater than 10 kyr this holds pro found implications for geomorphological theory and for studies of erosion

geomorphic constraints on active mountain growth by the lateral propagation of fault related folding a case study on yumu shan ne tibet the mountain range of the yumu shan in ne tibet is the topographic expression of actively growing fault related folds developed in the hanging walls of a system of mostly northeast vergent blind thrusts here we present a tibetan example on the geomorphic response to lateral fold propagation using both qualitative analysis of the geomorphic characteristics of this region e g wind and water gaps drainage density and along strike topography of the range crest and quantitative analysis based on cosmogenic be 10 surface exposure dating and optically stimulated luminescence dating on the rates of uplift and lateral propagation of the anticline the elevations of the past positions of successively deflected paleo rivers show a systematic decrease toward the eastern tip of the anticline in tandem with an eastward decrease in drainage density combining the age data obtained by cosmogenic be 10 and osl dating methods with the heights of abandoned terraces we calculated average uplift and lateral propagation rates of similar to 378 mm ka over the past similar to 185 ka and similar to 40 mm yr over the past similar to 150 ka respectively our single site evaluation of the relation between tear faulting and channel deflection suggests that the tear faulting occurs along weakened bedrock already dissected by the former stream this finding is inconsistent with the conventional hypothesis that the route of the deflecting stream is controlled by the orientation of the tear faulting zone topographic vertical and lateral fold growth of the yumu shan were probably driven by the eastward propagation of a blind thrust since the late neogene following the initial deposition of sediments in the hexi corridor which were transported from the qilian shan c 2011 elsevier ltd all rights reserved the mountain range of the yumu shan in ne tibet is the topographic expression of actively growing fault related folds developed in the hanging walls of a system of mostly northeast vergent blind thrusts here we present a tibetan example on the geomorphic response to lateral fold propagation using both qualitative analysis of the geomorphic characteristics of this region e g wind and water gaps drainage density and along strike topography of the range crest and quantitative analysis based on cosmogenic be 10 surface exposure dating and optically stimulated luminescence dating on the rates of uplift and lateral propagation of the anticline the elevations of the past positions of successively deflected paleo rivers show a systematic decrease toward the eastern tip of the anticline in tandem with an eastward decrease in drainage density combining the age data obtained by cosmogenic be 10 and osl dating methods with the heights of abandoned terraces we calculated average uplift and lateral propagation rates of similar to 378 mm ka over the past similar to 185 ka and similar to 40 mm yr over the past similar to 150 ka respectively our single site evaluation of the relation between tear faulting and channel deflection suggests that the tear faulting occurs along weakened bedrock already dissected by the former stream this finding is inconsistent with the conventional hypothesis that the route of the deflecting stream is controlled by the orientation of the tear faulting zone topographic vertical and lateral fold growth of the yumu shan were probably driven by the eastward propagation of a blind thrust since the late neogene following the initial deposition of sediments in the hexi corridor which were transported from the qilian shan c 2011 elsevier ltd all rights reserved