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101. Late Pleistocene / Holocene slip rate of the Zhangye thrust (Qilian Shan, China) and implications for the active growth of the northeastern Tibetan Plateau

Author

Hetzel, Ralf, Tao, M. X., Stokes, S., Niedermann, Samuel, Ivy-Ochs, Susan, Gao, B., Strecker, Manfred Reinhard, and Kubik, Peter W.

Subjects
Institut für Geowissenschaften
Abstract

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)

Published
2004

104. Strong rocks sustain ancient postorogenic topography in southern Africa

Author

Scharf, Taryn E., Codilean, Alexandru T., de Wit, Maarten, Jansen, John D., Kubik, Peter W., Scharf, Taryn E., Codilean, Alexandru T., de Wit, Maarten, Jansen, John D., and Kubik, Peter W.

Abstract

The Cape Mountains of southern Africa exhibit an alpine-like topography in conjunction with some of the lowest denudation rates in the world. This presents an exception to the often-cited coupling of topography and denudation rates and suggests that steep slopes alone are not sufficient to incite the high denudation rates with which they are commonly associated. Within the Cape Mountains, slope angles are often in excess of 30 degrees and relief frequently exceeds 1 km, yet Be-10-based catchment-averaged denudation rates vary between 2.32 +/- 0.29 m/m.y. and 7.95 +/- 0.90 m/m.y. We attribute the maintenance of rugged topography and suppression of denudation rates primarily to the presence of physically robust and chemically inert quartzites that constitute the backbone of the mountains. Be-10-based bedrock denudation rates on the interfluves of the mountains vary between 1.98 +/- 0.23 m/m.y. and 4.61 +/- 0.53 m/m.y. The close agreement between the rates of catchment-averaged and interfluve denudation indicates topography in steady state. These low denudation rates, in conjunction with the suggestion of geomorphic stability, are in agreement with the low denudation rates (<20 m/m.y.) estimated for southern Africa during the late Cenozoic by means of cosmogenic nuclide, thermochronology, and offshore sedimentation analyses. Accumulatively, these data suggest that the coastal hinterland of the subcontinent may have experienced relative tectonic stability throughout the Cenozoic., AuthorCount:5

Published
2013
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105. Strong rocks sustain ancient postorogenic topography in southern Africa

Author

Scharf, Taryn E, Codilean, Alexandru T, De Wit, Maarten, Jansen, John D, Kubik, Peter W, Scharf, Taryn E, Codilean, Alexandru T, De Wit, Maarten, Jansen, John D, and Kubik, Peter W

Abstract

The Cape Mountains of southern Africa exhibit an alpine-like topography in conjunction with some of the lowest denudation rates in the world. This presents an exception to the often-cited coupling of topography and denudation rates and suggests that steep slopes alone are not sufficient to incite the high denudation rates with which they are commonly associated. Within the Cape Mountains, slope angles are often in excess of 30° and relief frequently exceeds 1 km, yet 10Be-based catchment-averaged denudation rates vary between 2.32 ± 0.29 m/m.y. and 7.95 ± 0.90 m/m.y. We attribute the maintenance of rugged topography and suppression of denudation rates primarily to the presence of physically robust and chemically inert quartzites that constitute the backbone of the mountains. 10Be-based bedrock denudation rates on the interfluves of the mountains vary between 1.98 ± 0.23 m/m.y. and 4.61 ± 0.53 m/m.y. The close agreement between the rates of catchment-averaged and interfluve denudation indicates topography in steady state. These low denudation rates, in conjunction with the suggestion of geomorphic stability, are in agreement with the low denudation rates (/m.y.) estimated for southern Africa during the late Cenozoic by means of cosmogenic nuclide, thermochronology, and offshore sedimentation analyses. Accumulatively, these data suggest that the coastal hinterland of the subcontinent may have experienced relative tectonic stability throughout the Cenozoic.

Published
2013

108. Reconstruction of a complex late Quaternary glacial landscape in the Cordillera de Cochabamba (Bolivia) based on a morphostratigraphic and multiple dating approach.

Author

May, Jan-Henrik, Zech, Jana, Zech, Roland, Preusser, Frank, Angollo, Jaime, Kubik, Peter W., Veit, Heinz, May, Jan-Henrik, Zech, Jana, Zech, Roland, Preusser, Frank, Angollo, Jaime, Kubik, Peter W., and Veit, Heinz

Abstract

Although glacial landscapes have previously been used for the reconstruction of late Quaternary glaciations inthe Central Andes, only few data exist for the Eastern Cordillera in Bolivia. Here, we present results fromdetailed morphostratigraphic mapping and new data of surface exposure dating (SED), optically stimulatedluminescence (OSL), and radiocarbon dating (14C) from the Huara Loma Valley, Cordillera de Cochabamba(Bolivia). Discrepancies between individual dating methods could be addressed within the context of a solidgeomorphic framework. We identified two major glaciations. The older is not well constrained by theavailable data, whereas the younger glaciation is subdivided into at least four major glacial stages. Regardingthe latter, a first advance dated to ~29–25 ka occurred roughly contemporaneous with the onset of the globallast glacial maximum (LGM) and was followed by a less extensive (re-)advance around 20–18 ka. The locallast glacial maximum (LLGM) in the Huara Loma Valley took place during the humid lateglacial ~17–16 ka,followed by several smaller readvances until ~10–11 ka, and complete deglaciation at the end of the EarlyHolocene.

Published
2011

118. Synchronous Last Glacial Maximum across the Anatolian peninsula

Author

Akcar, Naki, Yavuz, Vural, Yesilyurt, Serdar, Ivy-Ochs, Susan, Reber, Regina, Bayrakdar, Cihan, Kubik, Peter W., Zahno, Conradin, Schlunegger, Fritz, and Schluchter, Christian

Abstract

Uludağ is a prominent mountain in northwestern Turkey where glacial deposits have been documented in the Kovuk Valley and the glacial history has been reconstructed based on 31 cosmogenic 10Be exposure ages from glacially transported boulders and bedrock. The results suggest that the Kovuk Glacier began advancing before 26.5±1.6 ka. It reached its maximum extent at 20.3±1.3 ka, followed by a re-advance at 19.3±1.2 ka, both during the global Last Glacial Maximum (LGM) within Marine Isotope Stage 2. The timing of the LGM glaciations in the Kovuk Valley is consistent with the investigated LGM glaciations in other mountains of Anatolia, the Mediterranean and the Alps. Based on the geomorphological ice margin reconstruction and using the accumulation/ablation area ratio (AAR) approach, the equilibrium line altitude (ELA) of the Kovuk LGM glacier was c.2000 m above sea level for an estimated AAR of 0.67. This indicates a c.1000 m lowering of the ELA for the LGM compared with the modern ELA estimate. These lines of evidence are consistent with the LGM glaciers that have been documented elsewhere in the Anatolian Mountains.Supplementary material:An input file for exposure age calculation in the CRONUS-Earth online calculator and an KML file for sample locations are available at http://www.geolsoc.org.uk/SUP18878

Published
2017
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133. Combination of Numerical Dating Techniques Using 10Be in Rock Boulders and 14C of Resilient Soil Organic Matter for Reconstructing the Chronology of Glacial and Periglacial Processes in a High Alpine Catchment during the Late Pleistocene and Early Holocene

Author

Favilli, Filippo, primary, Egli, Markus, additional, Brandova, Dagmar, additional, Ivy-Ochs, Susan, additional, Kubik, Peter W, additional, Maisch, Max, additional, Cherubini, Paolo, additional, and Haeberli, Wilfried, additional

Published
2009
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