TY - JOUR A1 - Hetzel, Ralf A1 - Niedermann, Samuel A1 - Tao, Mingxin A1 - Kubik, Peter W. A1 - Strecker, Manfred T1 - Climatic versus tectonic control on river incision at the margin of NE Tibet: Be-10 exposure dating of river terraces at the mountain front of the Qilian Shan JF - Journal of geophysical research : Earth surface N2 - [1] We document late Pleistocene - Holocene aggradation and incision processes at the mountain front of the Qilian Shan, an active intracontinental fold-and-thrust belt accommodating a significant portion of the India-Asia convergence. The Shiyou River cuts through a NNE vergent fault propagation fold with Miocene red beds in the core and Pliocene - Quaternary growth strata on the northern forelimb. South of the anticline, Miocene strata dip 20 degrees SSW, suggesting a similar orientation for the basal decollement. After aggradation of an similar to 150-m-thick, late Pleistocene valley fill, the Shiyou River formed three terraces. The highest terrace, located 170 m above the river, constitutes the top of the fill. The other terraces are fill cut terraces: their treads are located 130 - 105 m and 37 m above the river, respectively. The 10 Be exposure dating of the terraces suggests that river incision accelerated from 0.8 +/- 0.2 mm yr(-1) to similar to 10 mm yr(-1) at 10 - 15 kyr. We interpret fast Holocene river incision as largely unrelated to tectonic forcing. The late Pleistocene incision rate of 0.8 +/- 0.2 mm yr(-1) places an upper limit of 2.2 +/- 0.5 mm yr(-1) on the horizontal shortening rate, assuming that incision is solely caused by rock uplift above a decollement dipping 20 degrees. However, the actual shortening rate may lie between similar to 2.2 mm yr(-1) and zero because deformation of the terraces and the valley fill cannot be unequivocally demonstrated. Our estimate is consistent with the bulk shortening rate of similar to 5 - 10 mm yr(-1) across several faults in NE Tibet derived from neotectonic and GPS data, although in case of the Shiyou River, Holocene deformation is barely discernible owing to intense climate-induced river incision. Y1 - 2006 U6 - https://doi.org/10.1029/2005JF000352 SN - 2169-9003 SN - 2169-9011 VL - 111 PB - Union CY - Washington ER - TY - JOUR A1 - Schildgen, Taylor F. A1 - Robinson, Ruth A. J. A1 - Savi, Sara A1 - Phillips, William M. A1 - Spencer, Joel Q. G. A1 - Bookhagen, Bodo A1 - Scherler, Dirk A1 - Tofelde, Stefanie A1 - Alonso, Ricardo N. A1 - Kubik, Peter W. A1 - Binnie, Steven A. A1 - Strecker, Manfred T1 - Landscape response to late Pleistocene climate change in NW Argentina: Sediment flux modulated by basin geometry and connectivity JF - Journal of geophysical research : Earth surface N2 - Fluvial fill terraces preserve sedimentary archives of landscape responses to climate change, typically over millennial timescales. In the Humahuaca Basin of NW Argentina (Eastern Cordillera, southern Central Andes), our 29 new optically stimulated luminescence ages of late Pleistocene fill terrace sediments demonstrate that the timing of past river aggradation occurred over different intervals on the western and eastern sides of the valley, despite their similar bedrock lithology, mean slopes, and precipitation. In the west, aggradation coincided with periods of increasing precipitation, while in the east, aggradation coincided with decreasing precipitation or more variable conditions. Erosion rates and grain size dependencies in our cosmogenic Be-10 analyses of modern and fill terrace sediments reveal an increased importance of landsliding compared to today on the west side during aggradation, but of similar importance during aggradation on the east side. Differences in the timing of aggradation and the Be-10 data likely result from differences in valley geometry, which causes sediment to be temporarily stored in perched basins on the east side. It appears as if periods of increasing precipitation triggered landslides throughout the region, which induced aggradation in the west, but blockage of the narrow bedrock gorges downstream from the perched basins in the east. As such, basin geometry and fluvial connectivity appear to strongly influence the timing of sediment movement through the system. For larger basins that integrate subbasins with differing geometries or degrees of connectivity (like Humahuaca), sedimentary responses to climate forcing are likely attenuated. KW - berylium-10 KW - optically stimulated luminescence KW - Humahuaca Basin KW - South American Monsoon System KW - fluvial terraces KW - landscape connectivity Y1 - 2016 U6 - https://doi.org/10.1002/2015JF003607 SN - 2169-9003 SN - 2169-9011 VL - 121 SP - 392 EP - 414 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Kober, Florian A1 - Zeilinger, Gerold A1 - Hippe, Kristina A1 - Marc, Odin A1 - Lendzioch, Theodora A1 - Grischott, Reto A1 - Christl, Marcus A1 - Kubik, Peter W. A1 - Zola, Ramiro T1 - Tectonic and lithological controls on denudation rates in the central Bolivian Andes JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - The topographic signature of a mountain belt depends on the interplay of tectonic, climatic and erosional processes, whose relative importance changes over times, while quantifying these processes and their rates at specific times remains a challenge. The eastern Andes of central Bolivia offer a natural laboratory in which such interplay has been debated. Here, we investigate the Rio Grande catchment which crosses orthogonally the eastern Andes orogen from the Eastern Cordillera into the Subandean Zone, exhibiting a catchment relief of up to 5000 m. Despite an enhanced tectonic activity in the Subandes, local relief, mean and modal slopes and channel steepness indices are largely similar compared to the Eastern Cordillera and the intervening Interandean Zone. Nevertheless, a dataset of 57 new cosmogenic 10Be and 26AI catchment wide denudation rates from the Rio Grande catchment reveals up to one order of magnitude higher denudation rates in the Subandean Zone (mean 0.8 mm/yr) compared to the upstream physiographic regions. We infer that tectonic activity in the thrusting dominated Subandean belt causes higher denudation rates based on cumulative rock uplift investigations and due to the absence of a pronounced climate gradient. Furthermore, the lower rock strength of the Subandean sedimentary units correlates with mean slopes similar to the ones of the Eastern Cordillera and Interandean Zone, highlighting the fact, that lithology and rock strength can control high denudation rates at low slopes. Low denudation rates measured at the outlet of the Rio Grande catchment (Abapo) are interpreted to be a result of a biased cosmogenic nuclide mixing that is dominated by headwater signals from the Eastern Cordillera and the Interandean zone and limited catchment sediment connectivity in the lower river reaches. Therefore, comparisons of short- (i.e., sediment yield) and millennial denudation rates require caution when postulating tectonic and/or climatic forcing without detailed studies. (C) 2015 The Authors. Published by Elsevier B.V. KW - Rio Grande KW - seismicity KW - uplift KW - rock strength KW - cosmogenic nuclides KW - denudation Y1 - 2015 U6 - https://doi.org/10.1016/j.tecto.2015.06.037 SN - 0040-1951 SN - 1879-3266 VL - 657 SP - 230 EP - 244 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bloethe, Jan H. A1 - Munack, Henry A1 - Korup, Oliver A1 - Fuelling, Alexander A1 - Garzanti, Eduardo A1 - Resentini, Alberto A1 - Kubik, Peter W. T1 - Late Quaternary valley infill and dissection in the Indus River, western Tibetan Plateau margin JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - The Indus, one of Earth's major rivers, drains large parts of the NW Himalaya and the Transhimalayan ranges that form part of the western Tibetan Plateau margin. In the western Himalayan syntaxis, where local topographic relief exceeds 7 km, the Indus has incised a steep bedrock gorge at rates of several mm yr(-1). Upstream, however, the upper Indus and its tributaries alternate between bedrock gorges and broad alluvial flats flanked by the Ladakh and Zanskar ranges. We review the late Quaternary valley history in this region with a focus on the confluence of the Indus and Zanskar Rivers, where vast alluvial terrace staircases and lake sediments record major episodes of aggradation and incision. New absolute dating of high-level fluvial terrace remnants using cosmogenic Be-10, optically and infrared stimulated luminescence (OSL, IRSL) indicates at least two phases of late Quaternary valley infilling. These phases commenced before similar to 200 ka and similar to 50-20 ka, judging from terrace treads stranded >150 m and similar to 30-40 m above modern river levels, respectively. Numerous stacks of lacustrine sediments that straddle the Indus River >200 km between the city of Leh and the confluence with the Shyok River share a distinct horizontal alignment. Constraints from IRSL samples of lacustrine sequences from the Leh-Spituk area reveal a protracted lake phase from >177 ka to 72 ka, locally accumulating >50-m thick deposits. In the absence of tectonic faulting, major lithological differences, and stream capture, we attribute the formation of this and other large lakes in the region to natural damming by large landslides, glaciers, and alluvial fans. The overall patchy landform age constraints from earlier studies can be reconciled by postulating a major deglacial control on sediment flux, valley infilling, and subsequent incision that has been modulated locally by backwater effects of natural damming. While comparison with Pleistocene monsoon proxies reveals no obvious correlation, a lateor post-glacial sediment pulse seems a more likely source of this widespread sedimentation that has partly buried the dissected bedrock topography. Overall, the long residence times of fluvial, alluvial and lacustrine deposits in the region (>500 ka) support previous studies, but remain striking given the dominantly steep slopes and deeply carved valleys that characterise this high-altitude mountain desert. Recalculated late Quaternary rates of fluvial bedrock incision in the Indus and Zanskar of 1.5 +/- 0.2 mm yr(-1) are at odds with the longevity of juxtaposed valley-fill deposits, unless a lack of decisive lateral fluvial erosion helps to preserve these late Pleistocene sedimentary archives. We conclude that alternating, similar to 10(4)-yr long, phases of massive infilling and incision have dominated the late Quaternary history of the Indus valley below the western Tibetan Plateau margin. (C) 2014 Elsevier Ltd. All rights reserved. KW - Himalaya KW - Indus KW - Valley fills KW - Glaciation KW - Erosion KW - Lake sediment Y1 - 2014 U6 - https://doi.org/10.1016/j.quascirev.2014.04.011 SN - 0277-3791 VL - 94 SP - 102 EP - 119 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Munack, Henry A1 - Korup, Oliver A1 - Resentini, Alberto A1 - Limonta, Mara A1 - Garzanti, Eduardo A1 - Bloethe, Jan H. A1 - Scherler, Dirk A1 - Wittmann, Hella A1 - Kubik, Peter W. T1 - Postglacial denudation of western Tibetan Plateau margin outpaced by long-term exhumation JF - Geological Society of America bulletin N2 - The Indus River, one of Asia's premier rivers, drains the western Tibetan Plateau and the Nanga Parbat syntaxis. These two areas juxtapose some of the lowest and highest topographic relief and commensurate denudation rates in the Himalaya-Tibet orogen, respectively, yet the spatial pattern of denudation rates upstream of the syntaxis remains largely unclear, as does the way in which major rivers drive headward incision into the Tibetan Plateau. We report a new inventory of Be-10-based basinwide denudation rates from 33 tributaries flanking the Indus River along a 320 km reach across the western Tibetan Plateau margin. We find that denudation rates of up to 110 mm k.y.(-1) in the Ladakh and Zanskar Ranges systematically decrease eastward to 10 mm k.y.(-1) toward the Tibetan Plateau. Independent results from bulk petrographic and heavy mineral analyses support this denudation gradient. Assuming that incision along the Indus exerts the base-level control on tributary denudation rates, our data show a systematic eastward decrease of landscape downwearing, reaching its minimum on the Tibetan Plateau. In contrast, denudation rates increase rapidly 150-200 km downstream of a distinct knick-point that marks the Tibetan Plateau margin in the Indus River longitudinal profile. We infer that any vigorous headward incision and any accompanying erosional waves into the interior of the plateau mostly concerned reaches well below this plateau margin. Moreover, reported long-term (>10(6) yr) exhumation rates from low-temperature chronometry of 0.1-0.75 mm yr(-1) consistently exceed our Be-10-derived denudation rates. With averaging time scales of 10(3)-10(4) yr for our denudation data, we report postglacial rates of downwearing in a tectonically idle landscape. To counterbalance this apparent mismatch, denudation rates must have been higher in the Quaternary during glacial-interglacial intervals. Y1 - 2014 U6 - https://doi.org/10.1130/B30979.1 SN - 0016-7606 SN - 1943-2674 VL - 126 IS - 11-12 SP - 1580 EP - 1594 PB - American Institute of Physics CY - Boulder ER - TY - JOUR A1 - Hippe, Kristina A1 - Kober, Florian A1 - Zeilinger, Gerold A1 - Ivy-Ochs, Susan A1 - Maden, Colin A1 - Wacker, Lukas A1 - Kubik, Peter W. A1 - Wieler, Rainer T1 - Quantifying denudation rates and sediment storage on the eastern Altiplano, Bolivia, using cosmogenic Be-10, Al-26, and in situ C-14 JF - Geomorphology : an international journal on pure and applied geomorphology N2 - Denudation processes and sediment transfer are investigated in a high-elevation, low-relief environment (eastern Altiplano, Bolivia) using Be-10, Al-26, and in situ C-14 analysis in fluvial sediments. Concentrations of the long-lived nuclides Be-10 and Al-26 yield consistently low catchment-wide denudation rates of similar to 3-29 mm ky(-1) (integrating over 21-194 ky), which reflect the low geomorphic gradients and the discontinuity of fluvial transport along the eastern Altiplano margin. No significant correlation is recorded between denudation rates of individual catchments and morphological basin parameters (slope, area, elevation). This is attributed to the overall little variability in morphology. The agreement between the denudation rates and published modern sediment discharge data suggests steady landscape evolution of the eastern Altiplano from the latest Pleistocene until today. While Be-10 and Al-26 provide long-term estimates on sediment production, in situ cosmogenic C-14 is used to trace short-term sediment storage. In situ C-14 concentrations are comparatively low indicating that C-14 decayed during alluvial storage over at least the past similar to 11-20 ky. We assume storage at shallow depth (2 m) and consider the influence of soil-mantled hillslopes on the in situ C-14 concentration. Our results illustrate the importance of sediment storage even over short distances and demonstrate the potential of in situ C-14 to study sediment routing and transfer times within drainage systems. However, this study also demonstrates that the long-lived Be-10 and Al-26 nuclides can provide adequate estimates on long-term denudation rates even if sediment transport is not fast but interrupted by several thousands of years of storage. KW - Cosmogenic nuclides KW - Denudation KW - Sediment storage KW - In situ C-14 KW - Altiplano Y1 - 2012 U6 - https://doi.org/10.1016/j.geomorph.2012.07.031 SN - 0169-555X VL - 179 IS - 22 SP - 58 EP - 70 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kober, Florian A1 - Zeilinger, Gerald A1 - Ivy-Ochs, Susan A1 - Dolati, A. A1 - Smit, J. A1 - Kubik, Peter W. T1 - Climatic and tectonic control on fluvial and alluvial fan sequence formation in the Central Makran Range, SE-Iran JF - Global and planetary change N2 - The geomorphic evolution of the Makran Range of SE-Iran and SW-Pakistan has been controlled by the prevailing SW-Asian monsoon and Mediterranean winter rainfall climate and the surface uplift processes resulting from the Arabia-Eurasia collision. The impact of climate on Quaternary fluvial and alluvial sequence formation and their regional correlation has been little investigated due to limited age control of these sequences. Using Be-10 cosmogenic nuclide exposure ages we established a Middle to Late Pleistocene terrace chronology. Our record tentatively indicates that terrace levels were abandoned towards the transition to or during warmer/pluvial periods (interglacials and/or interstadials) back to Marine Isotope Stage (MIS) 7, but abandoned ages show a large spread. It is hypothesized that pluvial phases correspond with times of enhanced SW-monsoons and a northward shift of the Intertropical Convergence Zone (ITCZ). Furthermore, orbital periodidties can be deduced on frequencies related to obliquity and precession cycles. Overall, caution has to be placed in sampling and interpreting alluvial deposits, which may have complex inheritance patterns and spatially and temporarily variable catchment erosion histories and terrace-channel dynamics. Beside the dominant climate control on terrace formation, elevated channel steepness indices around major thrusts and numerous knickpoints indicate an additionally tectonic influence on terrace formation. Local incision rates (mean similar to 0.6-0.8 min.a(-1)) are variable in space and time but are similar to uplift rates obtained from coastal terraces and thus suggest a regional surface uplift. (C) 2013 Elsevier B.V. All rights reserved. KW - Cosmogenic nuclides KW - Monsoon KW - Climate KW - Tectonics KW - Terraces KW - Makran Y1 - 2013 U6 - https://doi.org/10.1016/j.gloplacha.2013.09.003 SN - 0921-8181 SN - 1872-6364 VL - 111 SP - 133 EP - 149 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kober, Florian A1 - Ivy-Ochs, Susan A1 - Zeilinger, Gerald A1 - Schlunegger, Fritz A1 - Kubik, Peter W. A1 - Baur, Heinrich A1 - Wieler, Rainer T1 - Complex multiple cosmogenic nuclide concentration and histories in the arid Rio Lluta catchment, northern Chile N2 - Terrestrial cosmogenic nuclide (TCN) concentrations measured in river sediments can be used to estimate catchment-wide denudation rates. By investigating multiple TCN the steadiness of sediment generation, transport and depositional processes can be tested. Measurements of Be-10, Ne-21 and Al-26 from the hyper- to semi-arid Rio Lluta catchment, northern Chile, yield average single denudation rates ranging from 12 to 75 m Myr(-1) throughout the catchment. Paired nuclide analysis reveals complex exposure histories for most of the samples and thus the single nuclide estimates do not exclusively represent catchment-wide denudation rates. The lower range of single nuclide denudation rates (12-17 m Myr(-1)), established with the noble gas Ne-21, is in accordance with palaeodenudation rates derived from Ne-21/Be-10 and Al-26/Be-10 ratio analysis. Since this denudation rate range is measured throughout the system, it is suggested that a headwater signal is transported downstream but modulated by a complex admixture of sediment that has been stored and buried at proximal hillslope or terrace deposits, which are released during high discharge events. That is best evidenced by the stable nuclide Ne-21, which preserves the nuclide concentration even during storage intervals. The catchment-wide single Ne-21 denudation rates and the palaeodenuation rates contrast with previous TCN-derived erosion rates from bedrock exposures at hillslope interfluves by being at least one order of magnitude higher, especially in the lower river course. These results support earlier studies that identified a coupling of erosional processes in the Western Cordillera contrasting with decoupled processes in the Western Escarpment and in the Coastal Cordillera. Y1 - 2009 UR - http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291096-9837 U6 - https://doi.org/10.1002/Esp.1748 SN - 0197-9337 ER - TY - JOUR A1 - Hetzel, Ralf A1 - Tao, M. X. A1 - Stokes, S. A1 - Niedermann, Samuel A1 - Ivy-Ochs, Susan A1 - Gao, B. A1 - Strecker, Manfred A1 - Kubik, Peter W. T1 - Late Pleistocene / Holocene slip rate of the Zhangye thrust (Qilian Shan, China) and implications for the active growth of the northeastern Tibetan Plateau N2 - We derive a slip rate for a thrust at the central Qilian Shan mountain front by combining structural investigations, satellite imagery, topographic profiling, luminescence dating, and Be-10 exposure dating. The seismically active Zhangye thrust transects late Pleistocene alluvial fan deposits and forms a prominent north facing scarp. The fault consists of two segments that differ in orientation, scarp height, and age. A series of loess-covered terraces records the uplift history of the western thrust segment. Loess accumulation on all terraces started at 8.5 +/- 1.5 kyr and postdates terrace formation. Gravels from the highest terrace yielded a Be-10 exposure age of 90 +/- 11 kyr, which dates the onset of faulting. With a displacement of 55-60 m derived from fault scarp profiles, this yields a vertical slip rate of 0.64 +/- 0.08 mm yr(-1). Along the eastern thrust segment, three Be-10 ages from the uplifted alluvial fan constrain that faulting started at similar to31 +/- 5 kyr. Together with a displacement of 25-30 m this leads to a vertical faulting rate of 0.88 +/- 0.16 mm yr(-1). A dip estimate of 40degrees to 60degrees for the fault plane combined with lower and upper limits of similar to0.6 and similar to0.9 mm yr(-1) for the vertical slip rate gives minimum and maximum horizontal shortening rates of 0.4 and 1.1 mm yr(-1) across the Zhangye thrust. Our results are consistent with geologic and GPS constraints, which suggest that NNE directed shortening across the northeastern Tibetan Plateau is distributed on several active faults with a total shortening rate of 4 to 10 mm yr(-1) Y1 - 2004 SN - 0278-7407 ER - TY - JOUR A1 - Hetzel, Ralf A1 - Tao, MX A1 - Niedermann, Samuel A1 - Strecker, Manfred A1 - Ivy-Ochs, Susan A1 - Kubik, Peter W. A1 - Gao, B. T1 - Implications of the fault scaling law for the growth of topography : mountain ranges in the broken foreland of north-east Tibet N2 - A fault scaling law suggests that, over eight orders of magnitude, fault length L is linearly related to maximum displacement D. Individual faults may therefore retain a constant ratio of D/L as they grow. If erosion is minor compared with tectonic uplift, the length and along-strike relief of young mountain ranges should thus reflect fault growth. Topographic profiles along the crests of mountain ranges in the actively deforming foreland of north-east Tibet exhibit a characteristic shape with maximum height near their centre and decreasing elevation toward the tips. We interpret the along-strike relief of these ranges to reflect the slip distribution on high-angle reverse faults. A geometric model illustrates that the lateral propagation rate of such mountain ranges may be deciphered if their length- to-height ratio has remained constant. As an application of the model, we reconstruct the growth of the Heli Shan using a long-term uplift rate of similar to1.3 mm yr(-1) derived from Ne-21 and Be-10 exposure dating Y1 - 2004 SN - 0954-4879 ER - TY - JOUR A1 - Hippe, Kristina A1 - Kober, Florian A1 - Zeilinger, Gerald A1 - Ivy-Ochs, Susan A1 - Kubik, Peter W. A1 - Wieler, Rainer T1 - Short and long-term denudation rates at the Altiplano margin, La Paz region, Bolivia Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/00167037 U6 - https://doi.org/10.1016/j.gca.2009.05.006 SN - 0016-7037 ER -