middle and late quaternary glacial lake outburst floods drainage diversions and reorganization of fluvial systems in northwestern eurasia abstract the middle and late pleistocene glaciations of northern eurasia had a great impact on the evolution of the modern drainage system this paper presents a review and synthesis on the palaeogeography of glacial lakes their drainage and impact on the re organization of the drainage systems during the last two glacial interglacial cycles we will focus on four regions 1 northern central europe and fennoscandia 2 the central part of the east european plain 3 the west siberian plain and 4 the aral caspian black sea area the main findings of the last decade s include the improved chronology of some major river system formation and of meltwater overflows across the continental drainage divides major drainage systems of the north central and west central part of the east european plain upper volga upper dnieper formed due to overspill of glacial lakes in late mis 6 with a partial re organization upper dnieper in mis 2 the aral caspian black sea cascade acted as a sink for glacial meltwater from the north the major meltwater yield to the aral and caspian seas occurred in mis 6 and late mis 5 in mis 2 the meltwater delivery via the volga valley into the caspian sea was low and therefore had only a minor influence on the sea level considerable meltwater discharge to the black sea through the dnieper river system occurred around the maximal stage of the mis 2 glaciation and ceased very quickly after the onset of deglaciation

denudation rates and a topography driven rainfall threshold in northern chile multiple cosmogenic nuclide data and sediment yield budgets abstract the quantification of geomorphic process rates on the outcrop and the orogen scale is important to describe accurately the interaction between the relative effects of erosion tectonics and climate on landscape evolution we report single and paired cosmogenic nuclide 10 be 26 al and 21 ne derived erosion rates and exposure ages on hillslope interfluves from the tectonically active western central andes that show a distinct spatial variation a positive correlation of erosion rates with elevation and present day rainfall rates is observed erosion rates at lower altitudes the hyperarid coastal cordillera and the western escarpment with the northern part of the atacama desert are extremely low and of the order of 10 100 cm my nominal exposure ages 1 6 my in contrast erosion rates at higher altitudes the semiarid western cordillera range up to 4600 cm my nominal exposure ages 0 02 0 1 my this latter average long term bedrock erosion rate record suggested to be coupled to an orographically controlled pattern of rainfall is also reflected in the pattern of denudation rates derived from a short term decadal record of limited sediment yield data specifically denudation rates calculated from sediment flux data are of a similar order of magnitude as erosion rates deduced from long lived cosmogenic nuclides from bedrock hillslope interfluves of the western cordillera nevertheless the production and the supply of sediment from the western andean slope are very limited analysis of multiple cosmogenic nuclides allows simultaneous determination of erosion rates and exposure ages but also reveals complex exposure histories of non bedrock samples such as boulders or amalgamated clast samples notably this study shows that saturation of nuclides usually assumed in studies where only a single nuclide is analyzed is rather the exception than the rule as revealed by erosion island plots constant erosion that started much later than the formation age of the rocks or episodic erosion by spalling can partially explain non steady state concentrations and more complicated exposure scenarios furthermore the use of multiple nuclides with different half lives allowed us to infer that no significant variations in long term erosion rates have occurred and that at the western escarpment erosion rates have been low and constant for most of the late neogene nevertheless the time intervals necessary to reach steady state concentrations for cosmogenic nuclides can be quite different from those needed for landscapes to reach steady state

large scale erosion rates from in situ produced cosmogenic nuclides in european river sediments abstract we have calculated long term erosion rates of 20 100 mm kyr from quartz contained 10be in the bedload of middle european rivers for catchments ranging from 102 to 105 km2 these rates average over 10 40 kyr and agree broadly with rock uplift incision and exhumation rates historic soil erosion rates and erosion rates calculated from the measured sediment loads of the same rivers moreover our new erosion rate estimates correlate well with lithology and relief however in the regen neckar loire and meuse catchments cosmogenic nuclide derived erosion rates are consistently 1 5 4 times greater than the equivalent rates derived from measured river loads this may be due to the systematic under representation of high magnitude low frequency transport events in the gauging records which cover less than a century alternatively the discrepancy may derive from spatially non uniform erosion and preferential tapping of deeper sections of the irradiation profile a third explanation relates the high cosmogenic nuclide derived erosion rates to inheritance of an elevated pleistocene erosion signal uncertainties associated with the cosmogenic nuclide derived erosion rate estimates are not greater than the potential errors in conventional estimates therefore the cosmogenic nuclide approach is an effective tool for rapid catchment wide assessment of time integrated rates of bedrock weathering and erosion and we anticipate its fruitful application to the quaternary sedimentary record

the erosion response to quaternary climate change quantified using uranium isotopes and in situ produced cosmogenic nuclides abstract studying how catchment erosion has responded to past climate change can help us better understand not only how landscape evolution operates but also predict the consequences of future climate change on soil resource availability recent years have seen the development of tools that allow a quantitative assessment of past changes in catchment erosion this work reviews the principles of the application of in situ produced cosmogenic nuclides and uranium isotopes to quantifying past erosion rates results highlight the role of periglacial processes and mass wasting in dictating how catchment erosion responds to climatic variability at the 10 kyr scale at the million year scale it is more difficult to untangle the role of climate and tectonics a strong coupling exists at the 10 kyr to 100 kyr scales between climatic cycles and the transfer time of regolith from source to sink this coupling reflects changes in sediment source that are either set by changes in vegetation cover at the catchment scale or by the storage of sediments on continental shelves at a larger scale although further analytical developments are required for these tools to reach their full potential existing works suggest that in the near future they will provide unprecedented quantitative insights on how soil and fluvial systems adapt to external perturbations climatic tectonic and or anthropic

predicting reach specific properties of fluvial terraces to guide future fieldwork a case study for the late quaternary river allier france with the fluver2 model numerical models have not yet systematically been used to predict properties of fluvial terrace records in order to guide fieldwork and sampling this paper explores the potential of the longitudinal profile model fluver2 to predict testable field properties of the relatively well studied late quaternary allier system in france for the allier terraces an overlapping 14c and u series chronology as well as a record of 10be erosion rates exist the fluver2 modelling exercise is focused on the last 50 ka of the upper allier reach because for this location and period the constraints of the available dating techniques are tightest a systematic calibration based on terrace occurrence and thicknesses was done using three internal parameters related to 1 the sediment erodibility 2 the sediment transport distance and 3 the sediment supply derived from the surrounding landscape as external model inputs the best available reconstructed tectonic climatic and base level data were used calibrated model outputs demonstrate a plausible match with the existing fluvial record validation of model output was done by comparing the modelled and measured timing of aggradation and incision phases for the three locations the modelled range of landscape erosion rates showed a reasonably good match with existing erosion rate estimates derived from 10be measurements of fluvial sands the quasi validated model simulation was subsequently used to make new testable predictions about the timing and location of aggradation and erosion phases for three locations along the allier river the validated simulations predict that along the allier reach specific dynamics of incision and aggradation related to the variations in sediment supply by major tributaries cause relevant differences in the local fluvial terrace stratigraphy numerical models have not yet systematically been used to predict properties of fluvial terrace records in order to guide fieldwork and sampling this paper explores the potential of the longitudinal profile model fluver2 to predict testable field properties of the relatively well studied late quaternary allier system in france for the allier terraces an overlapping 14 c and u series chronology as well as a record of 10 be erosion rates exist the fluver2 modelling exercise is focused on the last 50 ka of the upper allier reach because for this location and period the constraints of the available dating techniques are tightest a systematic calibration based on terrace occurrence and thicknesses was done using three internal parameters related to 1 the sediment erodibility 2 the sediment transport distance and 3 the sediment supply derived from the surrounding landscape as external model inputs the best available reconstructed tectonic climatic and base level data were used calibrated model outputs demonstrate a plausible match with the existing fluvial record validation of model output was done by comparing the modelled and measured timing of aggradation and incision phases for the three locations the modelled range of landscape erosion rates showed a reasonably good match with existing erosion rate estimates derived from 10 be measurements of fluvial sands the quasi validated model simulation was subsequently used to make new testable predictions about the timing and location of aggradation and erosion phases for three locations along the allier river the validated simulations predict that along the allier reach specific dynamics of incision and aggradation related to the variations in sediment supply by major tributaries cause relevant differences in the local fluvial terrace stratigraphy copyright 2016 john wiley sons ltd

dramatic increase in late cenozoic alpine erosion rates recorded by cave sediment in the southern rocky mountains abstract apparent increases in sedimentation rates during the past 5 ma have been inferred at sites around the globe to document increased terrestrial erosion rates but direct erosion rate records spanning this period are sparse modern and paleo erosion rates for a small alpine catchment 3108 m above sea level in the southern rocky mountains are measured using the cosmogenic radionuclides crns 10be and 26al in cave sediment bedrock on the overlying landscape surface and coarse bedload in a modern fluvial drainage the unique setting of the marble mountain cave system allows the inherited erosion rates to be interpreted as basin averaged erosion rates resulting in the first crn based erosion rate record from the rocky mountains spanning 5 myr pliocene erosion rates derived from the oldest cave sample 4 9 0 4 ma for the landscape above the cave are 4 9 1 1 m myr 1 mid pleistocene erosion rates are nearly an order of magnitude higher 33 1 2 7 to 41 3 3 9 m myr 1 and modern erosion rates are similar due to the effects of snow shielding these erosion rate estimates are likely higher than actual rates by 10 15 the most likely explanation for this dramatic increase in erosion rates which likely occurred shortly before 1 2 ma is an increase in the effectiveness of periglacial weathering processes at high elevations related to a cooler and wetter climate during the pleistocene providing support for the hypothesis that changes in late cenozoic climate are responsible for increased continental erosion

control of regional sea level by surface uplift and subsidence caused by magmatic underplating of earth s crust magmatic underplating of the crust is a common feature of major basalt provinces the emplacement of magma within the lithosphere leads to surface uplift with a magnitude of the order of 10 of the thickness of the underplated material the composition of associated igneous rock samples suggests that much of the underplated material is made of gabbro this gabbro is denser than the magma from which it crystallizes so uplift of earth s surface caused by the emplacement of magma at the crust mantle boundary must be followed by subsidence as the magma solidifies this subsidence is equal to approximately half the original uplift and takes place within 0 1 m y of injection of the magma the association of magmatic underplating with surface uplift followed by subsidence provides a mechanism for changes of sea level including previously unexplained episodic highstands of sea level

river incision and terrace formation in the late cenozoic of europe abstract late cenozoic environmental changes which affected european rivers are reviewed focusing especially on those of mid pleistocene times c 1 2 0 8 ma or around mis 22 and thereafter these involved dominating but fluctuating cold climate periglacial conditions shorter but major episodes of glaciation and brief interglacials there were also related sea level and tectonic responses the known history of european rivers in this period is individually varied but is predominantly marked by multiple stages of episodic incision the form of which changed in style at around the mid pleistocene transition it is suggested that the nature of climatic oscillations the dating of incision episodes and the processes that achieve this incision are as yet insufficiently understood fluvial process studies suggest that the onset of incision may broadly relate to changes in slope discharge sediment load and calibre and bedrock erodibility and these may all have been transformed as the direct or indirect result of mid pleistocene climatic changes common properties of basal sediments on strath terraces suggest that it was during the extended but variable cold stage episodes that both valley deepening and lateral widening occurred and that climatic change was the principal driver of episodic deep valley incision

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

10be derived himalayan denudation rates and sediment budgets in the ganga basin abstract the himalayas represent the archetype of mountain building due to active continental collision and are considered in many studies as the locus of intense interactions between climate denudation and tectonics estimates of modern denudation rates across the entire range remain however relatively sparse in this study in situ produced cosmogenic 10 be concentrations were measured in detritic quartz in order to determine basin scale denudation rates for the central part of the himalayan range river sand was sampled over several years in the main trans himalayan rivers from the himalayan front to the ganga outlet in bangladesh the calculated 10 be denudation rates of the trans himalayan river basins range from 0 5 to 2 4 mm yr 1 average 1 3 mm yr 1 and vary by up to a factor of 3 between sampling years these denudation rates strongly contrast with the 0 007 mm yr 1 denudation rate of southern tributary basins draining the indian craton this work also shows that in the ganga basin no systematic evolution of average 10 be concentrations is observed during floodplain transfer implying that distal samples can be used to estimate the integrated denudation rate of the whole central himalayan range samples from the ganga in bangladesh display remarkably low variability in 10 be concentration implying an average himalayan denudation rate of 1 0 1 1 mm yr 1 however within the floodplain several samples suggest a recent perturbation of sediment transport dynamics with a recent increase in the relative sediment contribution from southern tributaries the himalayan sediment flux deduced from the 10 be denudation rate of the range is 610 230 mt yr 1 this flux is consistent within uncertainty with sediment fluxes derived from sediment gauging the similarity of the two flux estimates suggests that himalayan erosion fluxes have remained stable over the last centuries even if the large uncertainties associated with each method hamper more precise assessments

detrital thermochronology of rhine elbe and meuse river sediment central europe implications for provenance erosion and mineral fertility here we present detrital apatite fission track aft zircon fission track zft and a few apatite u th he ahe data of middle pleistocene to modern rhine meuse and elbe river sediments in order to resolve processes that control detrital age distributions provenance erosion and mineral fertility we used a modelling approach to compare observed with theoretically predicted age distributions from an interpolated in situ aft and zft age map in situ cooling ages do show large differences in the rhine drainage basin facilitating the differentiation between different source regions inconsistencies between observed and theoretical age distributions of the meuse and elbe samples can be explained by mixing and reworking of sediments with different provenances meuse middle pleistocene terrace sediment and a yet unexplored source region with old aft ages elbe samples overall the results show that detrital thermochronology is capable of identifying the provenance of middle pleistocene to modern sediments the aft age distributions of rhine sediments are dominated 70 by aft ages representing the alps a possible explanation is higher erosion rates in the alps as compared to areas outside the alps a late pleistocene sample from the upper rhine graben contains apatite grains from the molasse and hegau volcanics which we explain with a shift of the headwaters of the rhine to the north as a result of intense middle pleistocene riss glaciation contrary to the observed dominance of alpine derived aft ages in rhine sediments the relative contribution of zircon ages with sources in the alps is lower and significantly decreases downstream suggesting a major source of zircons outside the alps this can be explained by increased zircon fertility of sediments derived from the rhenish massif therefore we conclude that erosion and mineral fertility are the main processes controlling detrital aft and zft age distributions of the sampled river sediment in case of the rhine samples aft age distributions are mainly controlled by differences in erosion rates whereas this impact is completely balanced by differences in mineral fertility for the zft data

quantifying quartz enrichment and its consequences for cosmogenic measurements of erosion rates from alluvial sediment and regolith abstract in situ cosmogenic 26 al and 10 be record the residence time of quartz grains near the earth s surface and thus can be used to measure whole catchment erosion rates averaged over millennial time scales quartz is enriched in hillslope regolith by the dissolution of more soluble minerals thus its residence time will be longer than the regolith average it has been noted that this introduces a bias into erosion rate estimates derived from cosmogenic nuclide concentrations in regolith or alluvium geomorphology 27 1999 131 but the magnitude of this bias has not previously been measured the enrichment of quartz in regolith and the resulting bias in cosmogenic erosion rate estimates can be quantified using concentrations of immobile elements such as zirconium in bedrock and regolith here we show that the erosion rate bias introduced by regolith dissolution is less than 12 across 22 granitic catchments that span a wide range of temperate climates except in extreme weathering environments biases due to regolith dissolution will be a small component of the overall uncertainty in cosmogenic erosion rate measurements

dominant covarying climate signals in the southern ocean and antarctic sea ice influence during the last three decades abstracta composite dataset comprising geopotential height sea surface temperature zonal and meridional surface winds precipitation cloud cover surface air temperature latent plus sensible heat fluxes and sea ice concentration has been investigated with the aim of revealing the dominant time scales of variability from 1982 to 2013 three covarying climate signals associated with variations in the sea ice distribution around antarctica have been detected through the application of the multiple taper method with singular value decomposition mtm svd features of the established patterns of variation over the southern hemisphere extratropics have been identified in each of these three climate signals in the form of coupled or individual oscillations the climate patterns considered here are the southern annular mode sam the pacific south american psa teleconnection the semiannual oscillation sao and the zonal wavenumber 3 zw3 mode it is shown that most of the sea ice temporal variance i

amount and controls of the quaternary denudation in the ardennes massif western europe it is still debated whether the primary control on the middle pleistocene denudation of the uplifted ardennes massif western europe is tectonic or climatic here based on geomorphological observations we calculate the amount of river incision and interfluve denudation in the meuse basin upstream of maastricht since 0 7 ma and we show that the main response to tectonic forcing was incision this allows us to provide first order estimates of the tectonic and climatic contributions to the denudation of the ardennes from a dataset of 71 remnants of a terrace level dated 0 7 ma we first derive a basin scale functional relationship linking incision with distances to the regional base level lc and to the source ls in the ourthe basin pertaining to the ardennian part of the meuse basin expressed as i i0 1 a lcb lsc i0 being the incision measured at the basin outlet this relationship calculates that river incision has removed 84 km3 of rock in the meuse basin upstream of maastricht since 0 7 ma in the same time 292 km3 were eroded from the interfluves a comparison of these volumes shows that the tectonically forced river incision accounts for 22 of the total post 0 7 ma denudation furthermore the mean denudation rate corresponding to our geomorphological estimate of the overall denudation in the meuse basin since 0 7 ma amounts to 27 mm ky a figure significantly lower than the 40 mm ky mean rate derived from 10be studies of terrace deposits of the meuse schaller et al 2004 this suggests that taken as a basin average the 10be derived rate is overestimated probably due to an overrepresentation of the erosion products of the rapidly incising valleys in the alluvial deposits copyright 2009 john wiley sons ltd

a note of caution on the use of boulders for exposure dating of depositional surfaces abstract exposure dating of boulders has been widely applied to determine the age of depositional surfaces under the assumption that the pre depositional nuclide component in most boulders is negligible here we present a case study on fluvial terraces at the active mountain front of the eastern andes where this assumption is clearly invalid because sandstone boulders n 13 from terraces at two sites contain a highly variable inherited 10be component and have apparent 10be ages that exceed the age of the respective surface by up to 90 ka likewise boulders from active stream channels n 5 contain a substantial inherited 10be component equivalent to 5 48 ka of exposure the age of the fluvial terraces is well determined by two approaches that allow to correct for the pre depositional nuclide component 10be dating of amalgamated pebbles and 10be depth profiles on sand samples at site 1 three terraces have 10be ages of 3 5 ka t2 11 13 ka t3 and 16 20 ka t4 which are consistent with the terrace stratigraphy the age of terrace t3 is confirmed by a calibrated 14 c age of 12 61 0 20 ka bp obtained from a wood sample at site 2 terrace t3 has a 10be age of 13 16 ka the average inherited 10be concentration of sand grains determined from depth profiles and stream sediments is small and equivalent to 1 3 ka of exposure in contrast the mean inheritance of pebbles and boulders is higher and equivalent to exposure times of 10 ka and 30 ka respectively these differences in the pre depositional nuclide component are related to the different provenance and transport history of sand pebbles and boulders the sand is derived from rapidly eroding miocene sediments exposed near the mountain front whereas the pebbles and boulders originate from triassic sandstones in the internal part of the fold and thrust belt on their way to the mountain front boulders and pebbles were temporarily stored and irradiated in alluvial fans that are currently reworked as sediment deposition in intramontane basins and their subsequent excavation is common in the andes and other fold and thrust belts the presence of pre depositional nuclide components should be evaluated when applying exposure dating at active mountain fronts

steady 10be derived paleoerosion rates across the plio pleistocene climate transition fish creek vallecito basin california rates of erosion over time provide a valuable tool for gauging tectonic and climatic drivers of landscape evolution here we measure 10be archived in quartz sediment from the fish creek vallecito basin to resolve a time series of catchment averaged erosion rates and to test the hypothesis that aridity and increased climate variation after ca 3 ma led to an increase in erosion rates in this semi arid ice free setting the fish creek vallecito basin located east of the peninsular ranges in southern california is an ideal setting to derive a plio pleistocene paleo erosion rate record the basin has a rapid sediment accumulation rate a detailed magnetostratigraphic age record and its stratigraphy has been exposed through recent rapid uplift and erosion a well defined source region of uniform lithology and low erosion rate provides a high reproducible 10be signal we find that paleo erosion rates were remarkably consistent between 1 and 4 ma averaging 38 24 m myr 2 modern catchment averaged erosion rates are similar to the paleo erosion rates the uniformity of erosion over the past 4 myr indicates the landscape was not significantly affected by late pliocene global climate change nor was it affected by a local long term increase in aridity

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

control of geomorphic processes on 10be concentrations in individual clasts complexity of the exposure history in gobi altay range mongolia the dating of alluvial landforms by cosmogenic nuclides requires distinguishing the pre deposition inheritance from the post deposition history of the clasts in the studied marker moreover estimating catchment scale erosion rates from the concentrations of cosmogenic nuclides in active alluvia requires a good knowledge of the local regional relationships between rock exhumation and transport through space and time this is still poorly known for timescales of tens of thousand years in order to document the evolution of clast exhumation and transport rates through time we analyze in situ 10be concentrations in boulders and cobbles from hillslopes to outlet of an arid mountainous catchment located in gobi altay mongolia strongly affected by global climatic changes during the pleistocene holocene period samples were collected on bedrock abandoned alluvial deposits active colluvia and alluvia our results show a large 10be scattering in the active river bed consistent with a low and discontinuous catchment erosion rate dominated by mass wasting and fluvial incision on the contrary pre exposure signal within abandoned terraces is much more homogeneous consistent with climatic pulses responsible of strong erosional events on hillslopes and rapid fluvial transport these results show that exhumation transport processes at the catchment scale vary in style and intensity through time as a consequence of climatic oscillations the occurrence of abrupt climatic changes during short periods of time recorded by 10be concentrations in abandoned alluvia raise questions about the temporal applicability of catchment erosion rates derived from cosmogenic nuclide concentrations measured in sediments of active rivers on the other hand strong and short erosion events limit and homogenize the pre exposure 10be signal in associated deposits like debris flows making them particularly suitable markers for dating in active tectonic and paleoclimatic studies

steady erosion rates in the himalayas through late cenozoic climatic changes sediment accumulation rates and thermal trackers suggest a substantial and global increase in erosion rates over the past few million years that increase is commonly associated with the impact of the northern hemisphere glaciation but methodological biases have led researchers to debate this hypothesis here we test whether himalayan erosion rates increased by measuring beryllium 10 10be in the sediment of the bengal bay seabed sediment originated from rocks that produced 10be under the impact of cosmic rays during erosion near surface thus the 10be concentrations indicate erosion rates the 10be concentration of the bengal bay sediment depends on the contributions of the ganga and brahmaputra rivers their sediments have distinct 10be concentrations because of distinct elevations and erosion in their drainage basins variable contributions could thus complicate erosion rate calculation we traced these contributions by a provenance study using the strontium sr and neodymium nd isotopic sediment compositions within uncertainties of 30 our reconstructed past erosion rates show no long term increase for the past six million years this stability suggests that climatic changes during the late cenozoic have an undetectable impact on the erosion patterns in the himalayas at least on the ten thousand to million year timescales accounted for by our dataset long term himalayan erosion rates remained stable through the global climatic changes of the past six million years according to the cosmogenic nuclide composition of terrestrial sediments recovered from the bay of bengal

a 30 000 yr record of erosion rates from cosmogenic 10be in middle european river terraces abstract cosmogenic 10 be in river borne quartz sand records a time integrated erosion rate representative of an entire drainage basin when sequestered in a terrace of known age paleo erosion rates may be recovered from the nuclide content of the terrace material paleo erosion rates between 30 and 80 mm kyr are determined from terrace sediments 200 to 30 000 yr in age of the allier and dore rivers france and the meuse maas river the netherlands erosion rates determined from cosmogenic nuclides on terraces from the allier river are consistent with rates derived from the sedimentary fill of a lake in the allier catchment a strong decrease in cosmogenic nuclide derived erosion rates from terraces of the meuse river with late pleistocene to holocene age is observed the paleo erosion signal from cosmogenic nuclides records projection of the elevated late pleistocene erosion rate into the time integrated rates derived from middle european rivers

dating soils and alluvium with cosmogenic 21ne depth profiles case studies from the pajarito plateau new mexico usa abstract 21 ne depth profiles measured from amalgamated samples of sand sized quartz from the quaternary bandelier tuff were used to estimate inheritance corrected exposure ages in stream terraces and an alluvial fan on the pajarito plateau stable alluvium and associated soils display a downward decreasing type i nuclide profile pattern bioturbated colluvium with uniform type iii nuclide concentrations has buried these alluvial surfaces another possible profile type with downward increasing nuclide concentrations type ii is described but was not found on the pajarito plateau we present mathematical models for each of the profile patterns relating nuclide concentration to inheritance time averaged bulk density and either exposure time or burial rate curve fits of type i profiles are used to estimate the age of alluvial landforms a burial correction technique for deposits buried by younger colluvium is also presented inheritance and burial corrected 21 ne surface exposure ages of 144 17 ka and 63 8 ka for two pajarito plateau stream terraces agree within error with independent soil profile development index dates of 160 ka and 68 78 ka a soil overlying the 50 60 ka el cajete pumice yields an inheritance corrected 21 ne exposure age of 44 11 ka that also agrees closely with a 14 c age on soil charcoal of 41 ka these results demonstrate that reliable cosmogenic 21 ne exposure ages can be obtained for fine grained alluvial surfaces with the depth profile technique

dynamic equilibrium among erosion river incision and coastal uplift in the northern and central apennines italy erosion river incision and uplift rates in the northern and central apennines italy since 0 9 ma are determined from new cosmogenic nuclide data beryllium 10 concentrations in modern and middle pleistocene sediments indicate erosion rates from 0 20 to 0 58 mm yr these rates are similar to estimates of sediment yield 0 12 0 44 mm yr river incision 0 35 mm yr and uplift 0 01 1 0 mm yr rates inferred from other methods that integrate landscape process rates since the early pleistocene these rates of landscape change are significantly lower than long term exhumation rates of 1 2 mm yr since ca 4 5 ma inferred from thermochronometry collectively these data suggest that hillslope erosion and river incision rates in the northern and central apennines have balanced local uplift rates for 1 my but that exhumation rates have slowed significantly since emergence of the mountain chain in the pliocene this condition of dynamic equilibrium was potentially achieved within ca 3 ma similar to some model predictions of hillslope and fluvial system adjustment

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

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

measured rates of sedimentation what exactly are we estimating and why abstract data on rates of sedimentation are essential in studies of sedimentation systems these data are obtained in three main study contexts 1 the study of sedimentation systems that are active today 2 the source to sink study of sedimentation systems that no longer are active and 3 the study of the relationship between accumulation rate and measurement timespan the aim of this paper is to question the meaning of measured rates of sedimentation and their interpretability particularly in these three contexts individual measurements of rate of sedimentation must always be interpreted with care firstly there are different definitions for instance with different statistical support or measurement dimension values that are defined differently cannot be compared directly secondly appropriate sampling schemes must have been used for the measurement this minimises sampling bias thirdly the inherent limitations of the data sources must be taken into account rates of sedimentation can usually be measured successfully in active sedimentation systems the same is not true for systems that are no longer active these can only be studied using the stratigraphic successions left behind rates of erosion can never be measured successfully in stratigraphic successions rate of sedimentation is essentially a ratio an amount of sedimentation per length of time therefore the obvious strategy to use in determining it is first to measure the amount and the time independently then to combine the values the amount can be measured in terms of thickness or volume or mass per unit area the duration of the time interval can be preset using quasi continuous measurement techniques or site reoccupation or it can be identified from interval specific sedimentary structures or it can be measured using dated horizons an alternative strategy is to use a surrogate measurement variable rates of erosion in ancient systems are usually measured in this way using cosmogenic radionuclide concentrations these two strategies are reviewed in this paper sets of measurements made in systems that are active today can certainly be used to estimate the rate of sedimentation for the system as a whole this estimation is best carried out using geostatistical estimation techniques the alternative is simply to average the measured rate values this latter approach should not be used however because the mean sedimentation rate in a system gives information only about the net sediment movement at the system boundaries it says nothing at all about how the system is operating or about its spatial and temporal variability measurements of rates of sedimentation made for source to sink studies are necessarily made in stratigraphic successions the measurements are used to estimate quantities in the sediment mass budget equation the amount of decumulation is inherently incapable of being measured in stratigraphic successions therefore there are always unknowns in the mass budget equation whenever the lithic surface at the start of the time interval considered cannot be recognised everywhere this means that the mass budget equation is applicable in practice only when all the systems involved in the study are entirely non erosional for that entire time interval a highly unrealistic situation the consistently inverse relationship documented between accumulation rates and measurement timespan is taken usually to indicate that this relationship is substantially scale invariant this in turn is often taken as indicating that the stratigraphic record is fractal in nature there are nevertheless grounds for doubt all of which relate to the ways that the data are collected and used for estimation the relationship is in fact the natural mathematical result of last in first out lifo operation and is produced in any type of system in which addition and removal processes both operate it says nothing particular about sedimentation processes the future analysis of accumulation rate data collected from stratigraphic successions will sensibly be framed in the context of estimating the parameters of a lifo model

spatially averaged long term erosion rates measured from in situ produced cosmogenic nuclides in alluvial sediment spatially averaged erosion rates of small catchments can be accurately inferred from the concentrations of cosmogenic nuclides in stream sediment here we test this technique at two catchments by comparing erosion rates inferred from cosmogenic nuclides with rates of alluvial fan deposition over the past 16 000 years these two independent estimates agree within one standard error demonstrating that cosmogenic nuclide signatures of stream sediment can be used to measure spatially averaged long term erosion rates using this technique we show that long term erosion rates are an exponential function of average hillslope gradient at these sites

apparent late quaternary fault slip rate increase in the southern lower rhine graben central europe in regions of low strain long earthquake recurrence intervals 104 106 yrs and erosive processes limit preservation of quaternary markers suitable for distinguishing whether faults slip at uniform or secularly varying rates the lower rhine graben in the border region of germany the netherlands and belgium provides a unique opportunity to explore quaternary slip rate variations in a region of low strain using the basal 2 29 0 29 ma and surface 700 80 ka contacts of the regionally extensive main terrace hauptterrasse deposited by the rhine and maas rivers these surfaces are vertically offset 3 140 m and 0 68 m respectively across individual fault strands within a distributed network of northwest trending slow slipping 80 of the sites record an apparent increase in slip rate for the more recent interval from 700 ka to present which corresponds to a period of increased uplift of the nearby rhenish massif and regional volcanism however the apparent increase in slip rate could result in part from erosion of the footwall surface below the main terrace leading to an apparent displacement that is smaller than the total vertical offset since the start of the quaternary prior work focused on characterization of these faults as seismic sources in the lower rhine graben has preferentially relied on the average fault slip rate constrained using the base of the main terrace we suggest that average fault slip rates calculated using the 700 ka main terrace surface are subjected to fewer uncertainties and sample a time interval that is more relevant for seismic hazard analysis electronic supplement 1 table of main terrace surface and basal contact offset measurements figure describing an unrealistic faulting scenario and a kml file with the fault trace mapping spanning the lower rhine graben 1 http www bssaonline org lookup suppl doi 10 1785 0120160197 dc1

paleoerosion rates from cosmogenic 10be in a 1 3 ma terrace sequence response of the river meuse to changes in climate and rock uplift abstract river borne quartz carries a cosmogenic nuclide memory that is a function of the catchment wide erosion rate this record may be preserved in fluvial deposits such as river terraces if the age of a terrace is independently known and transport time in the river system is relatively short then the upstream erosion rate at the time of terrace deposition can be determined we have used cosmogenic nuclides to date river terraces in the lower meuse catchment the netherlands and to obtain a 1 3 ma record of paleoerosion rates in a 104 km2 drainage basin comprising the ardennes mountains paleoerosion rates were uniform within the range of 25 35 mm ka from 1 3 to 0 7 ma after 0 7 ma erosion rates have increased progressively to late pleistocene values of around 80 mm ka around 0 7 ma both climatic and tectonic boundary conditions changed the amplitude and duration of climate cycles increased significantly resulting in long periods of sustained low temperatures in the meuse catchment in additio

estimating rates of denudation using cosmogenic isotope abundances in sediment we propose as a testable hypothesis a basin scale approach for interpreting the abundance of in situ produced cosmogenic isotopes an approach which considers explicitly both the isotope and sediment flux through a drainage basin unlike most existing models which are appropriate for evaluating in situ produced cosmogenic isotope abundance at discrete points on earth s surface our model is designed for interpreting isotope abundance in sediment because sediment is a mixture of materials in favourable cases derived from throughout a drainage basin we suggest that measured isotope abundances may reflect spatially averaged rates of erosion we investigate the assumptions and behaviour of our model and conclude that it could provide geomorphologists with a relatively simple means by which to constrain the rate of landscape evolution if a basin is in isotopic steady state and if sampled sediments are well mixed

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

correlation of fluvial terraces and temporal steady state incision on the onshore makran accretionary wedge in southeastern iran insight from channel profiles and 10be exposure dating of strath terraces we describe and summarize the geomorphology of fluvial terraces along the four major rivers draining the central onshore makran accretionary wedge in iran and describe uplifted marine terraces on the coast of this region thirty five strath terraces at different sites were dated using in situ produced cosmogenic 10 be concentrations from surfaces and depth profiles these new measurements reveal abandonment ages between ca 15 and 380 ka the age distribution allows determining the chronology of terrace levels and establishing regional correlations between two major regional levels the geographically widespread correspondence suggests that these two levels result from a regional climatically driven force systematic dating also provides evidence for time and spatial variations in incision rate which enables distinguishing between a regionally uniform incision rate of 0 3 0 4 mm a and higher local incision and or uplift 0 8 mm a rates these spatial changes are consistent with where localized tectonic activity is recognized in the field we also dated using 14 c in shells four uplifted marine terraces on the coast of the study area comparing incision rates derived from strath terraces 0 3 mm a with published uplift estimates from marine terraces 0 2 mm a reveals that fluvial rivers responded to a regional long term incision and surface uplift pattern this rate reflects the tectonically steady state of the wedge on a regional scale locally high incision rates delineate active faults and folds indicating that perfect steady state is unlikely on short length scales

co occurrence of northern and southern hemisphere blocks as partially synchronized chaos abstract teleconnections between the midlatitudes of the northern and southern hemispheres are diagnosed in national centers for environmental prediction national center for atmospheric research reanalysis data and separately in european centre for medium range weather forecasts reanalysis data the teleconnections are manifested as a small but significant tendency for blocking to occur simultaneously in the two hemispheres though at different longitudes and different relative latitudes during boreal winters over the period 1979 94 in both datasets one way to explain the correlations between blocking events is as an instance of synchronized chaos the tendency of some coupled chaotic systems to synchronize permanently or intermittently regardless of initial conditions as the coupling is weakened the systems no longer synchronize completely but small correlations between the states of the coupled systems are observed instead in previous work such behavior was observed in an idealized coupled hemi

dating sediment burial with in situ produced cosmogenic nuclides theory techniques and limitations abstract dating sediment burial over million year time scales is crucial in many areas of the earth sciences and archeology but is often difficult using traditional techniques sediment burial can be dated by the radioactive decay of cosmogenic nuclides provided that the sediment was exposed to cosmic rays prior to burial dating calculations are straightforward if sediment is buried deeply and rapidly enough to prevent cosmogenic nuclide production after burial however the analysis can be complicated by postburial production if sediment is insufficiently shielded from secondary cosmic ray nucleons and muons this paper discusses how buried sediments can be dated over timescales up to 5 myr using 26 al and 10 be in quartz

scaling factors for production rates of in situ produced cosmogenic nuclides a critical reevaluation abstract new scaling factors are presented describing the altitude and latitudinal dependence of production rates for in situ produced cosmogenic nuclides the new factors incorporate the influence of the non dipole contributions to the geomagnetic field on the cosmic ray flux the currently used scaling factors of lal earth planet sci lett 104 1991 424 439 are based on the assumption of a dipole field the overall strategy used in deriving the new scaling factors is however very similar to that of lal and relies on the same and or similar nuclear data in this reevaluation data are only used if the effective geomagnetic parameters inclination horizontal field strength can be reconstructed for the time of measurement the absorption free pathlengths for cosmic rays selected for this study are based on observational data at altitudes relevant for exposure age dating sea level to 7000 m at sea level and latitudes between 20 and 40 the new factors are up to 18 lower and at high altitudes more than 30 higher than those of lal in addition to accounting for the influence of the effective geomagnetic field and providing more applicable estimates of the new factors also allow for correction for the significant deviations from the standard pressure altitude relationship that exist in the atmosphere 10

fluvial networks of the iberian peninsula a chronological framework abstract knowledge of the evolution of spanish fluvial networks has improved during recent years as more river systems have been studied and more geochronological data has become available however the chronological framework is a major issue as the range of applications is limited by methodological constraints and spatial coverage is sparse integration of absolute dating methods with biostratigraphy and palaeomagnetism permits the recent evolution of these river systems to be reviewed the timing of incision from the late neogene to the present varies between the major iberian fluvial systems depending on the substrata and tectonic settings early pleistocene and older fluvial sequences in the core areas of the iberian peninsula provide a more extensive record of fluvial evolution and are better preserved than the terrace flights in the coastal lowlands middle pleistocene sequences are well developed in most of the major river systems in iberia particularly those of the tajo guadalquivir and aguas river and frequently represent the principal climatic cycles of that period although tectonic and sea level effects can also be seen for late pleistocene to holocene times the scheme becomes more complex our review suggests that each river system has responded differently to local and regional climate control glacial and periglacial processes in headwaters in high mountain areas glacio eustatic sea level changes and local and regional tectonic patterns

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

pliocene pleistocene incision of the green river kentucky determined from radioactive decay of cosmogenic 26al and 10be in mammoth cave sediments cosmogenic 26al and 10be in sediments washed into mammoth cave kentucky record the history of 3 5 m y of water table position governed by incision and aggradation of the green river a tributary of the ohio river upper levels of the cave formed during a period of slow river incision and were later filled with sediment due to river aggradation at 2 3 2 4 ma a brief surge of river incision ca 2 ma was followed by river stability and cave passage formation at a lower level rapid incision through 15 m of bedrock ca 1 5 ma was prompted by repositioning of the ohio river to its present course along an ice sheet margin renewed incision ca 1 2 ma and aggradation at 0 7 0 8 ma correlate with major ice advances in the ohio river basin measurements of 26al and 10be also indicate that sandstone capped uplands have maintained slow erosion rates of 2 7 m m y for the past 3 5 m y despite accelerated pleistocene river incision rates of 30 m m y

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

the mid pleistocene climate transition onset of 100 ka cycle lags ice volume build up by 280 ka the mid pleistocene climate transition mpt is the complex climatic change which brought the late pleistocene ice ages we explore the mpt in the time and frequency domains by new methods of time series analysis high resolution oxygen isotope records reveal that the ice volume related increase in 18o mean amplitude 0 29 0 05 1 transition midpoint 922 12 ka duration 40 9 ka significantly preceded the abrupt increase in the amplitude of the 100 ka cycle at 641 9 ka this finding can be quantitatively simulated using a simple ice bedrock model in which due to the additional ice the calving threshold is exceeded the simulated calving events prior to 650 ka are separated by 77 ka whereas after 650 ka they occur pseudo periodically with a mean period of nearly 100 ka the cause for the delay of the 100 ka calving cycle was not a slow bedrock relaxation rather the coincidental combination of insolation existing ice mass and bedrock depression