TY - GEN A1 - Licht, Alexis A1 - Dupont-Nivet, Guillaume A1 - Pullen, Alex A1 - Kapp, Paul A1 - Abels, Hemmo A. A1 - Lai, Zulong A1 - Guo, ZhaoJie A1 - Abell, Jordan A1 - Giesler, Dominique T1 - Resilience of the Asian atmospheric circulation shown by paleogene dust provenance T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The onset of modern central Asian atmospheric circulation is traditionally linked to the interplay of surface uplift of the Mongolian and Tibetan-Himalayan orogens, retreat of the Paratethys sea from central Asia and Cenozoic global cooling. Although the role of these players has not yet been unravelled, the vast dust deposits of central China support the presence of arid conditions and modern atmospheric pathways for the last 25 million years (Myr). Here, we present provenance data from older (42-33 Myr) dust deposits, at a time when the Tibetan Plateau was less developed, the Paratethys sea still present in central Asia and atmospheric pCO(2) much higher. Our results show that dust sources and near-surface atmospheric circulation have changed little since at least 42 Myr. Our findings indicate that the locus of central Asian high pressures and concurrent aridity is a resilient feature only modulated by mountain building, global cooling and sea retreat. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1114 KW - Chinese Loess Plateau KW - last glacial maximum KW - Tibetan Plateau KW - Yellow-River KW - climate KW - basin KW - evolution KW - ardification KW - monsoons KW - desert Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-436381 SN - 1866-8372 IS - 1114 ER - TY - JOUR A1 - Rohrmann, Alexander A1 - Heermance, Richard A1 - Kapp, Paul A1 - Cai, Fulong T1 - Wind as the primary driver of erosion in the Qaidam Basin, China JF - Earth & planetary science letters N2 - Deserts are a major source of loess and may undergo substantial wind-erosion as evidenced by yardang fields, deflation pans, and wind-scoured bedrock landscapes. However, there are few quantitative estimates of bedrock removal by wind abrasion and deflation. Here, we report wind-erosion rates in the western Qaidam Basin in central China based on measurements of cosmogenic Be-10 in exhumed Miocene sedimentary bedrock. Sedimentary bedrock erosion rates range from 0.05 to 0.4 mm/yr, although the majority of measurements cluster at 0.125 +/- 0.05 mm/yr. These results, combined with previous work, indicate that strong winds, hyper-aridity, exposure of friable Neogene strata, and ongoing rock deformation and uplift in the western Qaidam Basin have created an environment where wind, instead of water, is the dominant agent of erosion and sediment transport. Its geographic location (upwind) combined with volumetric estimates suggest that the Qaidam Basin is a major source (up to 50%) of dust to the Chinese Loess Plateau to the east. The cosmogenically derived wind erosion rates are within the range of erosion rates determined from glacial and fluvial dominated landscapes worldwide, exemplifying the effectiveness of wind to erode and transport significant quantities of bedrock. KW - wind KW - cosmogenic nuclide-dating KW - earth surface processes KW - Chinese Loess Plateau KW - climate KW - Asia Y1 - 2013 U6 - https://doi.org/10.1016/j.epsl.2013.03.011 SN - 0012-821X VL - 374 SP - 1 EP - 10 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Rohrmann, Alexander A1 - Kapp, Paul A1 - Carrapa, Barbara A1 - Reiners, Peter W. A1 - Guynn, Jerome A1 - Ding, Lin A1 - Heizler, Matthew T1 - Thermochronologic evidence for plateau formation in central Tibet by 45 Ma JF - Geology N2 - The timing of Tibetan plateau development remains elusive, despite its importance for evaluating models of continental lithosphere deformation and associated changes in surface elevation and climate. We present new thermochronologic data [biotite and K-feldspar Ar-40/Ar-39, apatite fission track, and apatite (U-Th)/He] from the central Tibetan plateau (Lhasa and Qiangtang terranes). The data indicate that over large regions, rocks underwent rapid to moderate cooling and exhumation during Cretaceous to Eocene time. This was coeval with >50% upper crustal shortening, suggesting substantial crustal thickening and surface elevation gain. Thermal modeling of combined thermochronometers requires exhumation of most samples to depths of <3 km between 85 and 45 Ma, followed by a decrease in erosional exhumation rate to low values of <0.05 mm/yr. The thermochronological results, when interpreted in the context of the deformation and paleoaltimetric history, are best explained by a scenario of plateau growth that began locally in central Tibet during the Late Cretaceous and expanded to encompass most of central Tibet by 45 Ma. Y1 - 2012 U6 - https://doi.org/10.1130/G32530.1 SN - 0091-7613 VL - 40 IS - 2 SP - 187 EP - 190 PB - American Institute of Physics CY - Boulder ER - TY - GEN A1 - Rohrmann, Alexander A1 - Heermance, Richard A1 - Kapp, Paul A1 - Cai, Fulong T1 - Wind as the primary driver of erosion in the Qaidam Basin, China (vol 374, pg 1, 2013) T2 - Earth & planetary science letters Y1 - 2015 U6 - https://doi.org/10.1016/j.epsl.2015.10.011 SN - 0012-821X SN - 1385-013X VL - 432 SP - 501 EP - 501 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Huang, Wentao A1 - van Hinsbergen, Douwe J. J. A1 - Maffione, Marco A1 - Orme, Devon A. A1 - Dupont-Nivet, Guillaume A1 - Guilmette, Carl A1 - Ding, Lin A1 - Guo, Zhaojie A1 - Kapp, Paul T1 - Lower Cretaceous Xigaze ophiolites formed in the Gangdese forearc: Evidence from paleomagnetism, sediment provenance, and stratigraphy JF - Earth & planetary science letters N2 - The India-Asia suture zone of southern Tibet exposes Lower Cretaceous Xigaze ophiolites and radiolarian cherts, and time-equivalent Asian-derived clastic forearc sedimentary rocks (Xigaze Group). These ophiolites have been interpreted to have formed in the forearc of the north-dipping subduction zone below Tibet that produced the Gangdese magmatic arc around 15-20 degrees N, or in the forearc of a subequatorial intra-oceanic subduction zone. To better constrain the latitude of the ophiolites, we carried out an integrated paleomagnetic, geochronologic and stratigraphical study on epi-ophiolitic radiolarites (Chongdui and Bainang sections), and Xigaze Group turbiditic sandstones unconformably overlying the ophiolite's mantle units (Sangsang section). Detrital zircon U-Pb geochronology of tuffaceous layers from the Chongdui section and sandstones of the Xigaze Group at the Sangsang section provides maximum depositional ages of 116.5 +/- 3.1 Ma and 128.8 +/- 3.4 Ma, respectively, for the Chongdui section and an Asian provenance signature for the Xigaze Group. Paleomagnetic analyses, integrated with rock magnetic experiments, indicate significant compaction-related inclination 'shallowing' of the remanence within the studied rocks. Two independent methods are applied for the inclination shallowing correction of the paleomagnetic directions from the Sangsang section, yielding consistent mean paleolatitudes of 16.2 degrees N 113 degrees N, 20.9 degrees N] and 16.8 degrees N [11.1 degrees N, 23.3 degrees N], respectively. These results are indistinguishable from recent paleolatitude estimates for the Gangdese arc in southern Tibet. Radiolarites from the Chongdui and Bainang sections yield low paleomagnetic inclinations that would suggest a sub-equatorial paleolatitude, but the distribution of the paleomagnetic directions in these rocks strongly suggests a low inclination bias by compaction. Our data indicate that spreading of the Xigaze ophiolite occurred in the Gangdese forearc, and formed the basement of the forearc strata. (C) 2015 Elsevier B.V. All rights reserved. KW - Xigaze ophiolite KW - sedimentary contact KW - paleomagnetism and rock magnetism KW - inclination shallowing Y1 - 2015 U6 - https://doi.org/10.1016/j.epsl.2015.01.032 SN - 0012-821X SN - 1385-013X VL - 415 SP - 142 EP - 153 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Huang, Wentao A1 - Dupont-Nivet, Guillaume A1 - Lippert, Peter C. A1 - van Hinsbergen, Douwe J. J. A1 - Dekkers, Mark J. A1 - Waldrip, Ross A1 - Ganerod, Morgan A1 - Li, Xiaochun A1 - Guo, Zhaojie A1 - Kapp, Paul T1 - What was the Paleogene latitude of the Lhasa terrane? A reassessment of the geochronology and paleomagnetism of Linzizong volcanic rocks (Linzhou basin, Tibet) JF - Tectonics N2 - The Paleogene latitude of the Lhasa terrane (southern Tibet) can constrain the age of the onset of the India-Asia collision. Estimates for this latitude, however, vary from 5 degrees N to 30 degrees N, and thus, here, we reassess the geochronology and paleomagnetism of Paleogene volcanic rocks from the Linzizong Group in the Linzhou basin. The lower and upper parts of the section previously yielded particularly conflicting ages and paleolatitudes. We report consistent Ar-40/Ar-39 and U-Pb zircon dates of similar to 52Ma for the upper Linzizong, and Ar-40/Ar-39 dates (similar to 51Ma) from the lower Linzizong are significantly younger than U-Pb zircon dates (64-63Ma), suggesting that the lower Linzizong was thermally and/or chemically reset. Paleomagnetic results from 24 sites in lower Linzizong confirm a low apparent paleolatitude of similar to 5 degrees N, compared to the upper part (similar to 20 degrees N) and to underlying Cretaceous strata (similar to 20 degrees N). Detailed rock magnetic analyses, end-member modeling of magnetic components, and petrography from the lower and upper Linzizong indicate widespread secondary hematite in the lower Linzizong, whereas hematite is rare in upper Linzizong. Volcanic rocks of the lower Linzizong have been hydrothermally chemically remagnetized, whereas the upper Linzizong retains a primary remanence. We suggest that remagnetization was induced by acquisition of chemical and thermoviscous remanent magnetizations such that the shallow inclinations are an artifact of a tilt correction applied to a secondary remanence in lower Linzizong. We estimate that the Paleogene latitude of Lhasa terrane was 204 degrees N, consistent with previous results suggesting that India-Asia collision likely took place by similar to 52Ma at similar to 20 degrees N. KW - remagnetization KW - rock magnetism KW - geochronology KW - India-Asia collision Y1 - 2015 U6 - https://doi.org/10.1002/2014TC003787 SN - 0278-7407 SN - 1944-9194 VL - 34 IS - 3 SP - 594 EP - 622 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Huang, Wentao A1 - van Hinsbergen, Douwe J. J. A1 - Dekkers, Mark J. A1 - Garzanti, Eduardo A1 - Dupont-Nivet, Guillaume A1 - Lippert, Peter C. A1 - Li, Xiaochun A1 - Maffione, Marco A1 - Langereis, Cor G. A1 - Hu, Xiumian A1 - Guo, Zhaojie A1 - Kapp, Paul T1 - Paleolatitudes of the Tibetan Himalaya from primary and secondary magnetizations of Jurassic to Lower Cretaceous sedimentary rocks JF - Geochemistry, geophysics, geosystems N2 - The Tibetan Himalaya represents the northernmost continental unit of the Indian plate that collided with Asia in the Cenozoic. Paleomagnetic studies on the Tibetan Himalaya can help constrain the dimension and paleogeography of "Greater India,' the Indian plate lithosphere that subducted and underthrusted below Asia after initial collision. Here we present a paleomagnetic investigation of a Jurassic (limestones) and Lower Cretaceous (volcaniclastic sandstones) section of the Tibetan Himalaya. The limestones yielded positive fold test, showing a prefolding origin of the isolated remanent magnetizations. Detailed paleomagnetic analyses, rock magnetic tests, end-member modeling of acquisition curves of isothermal remanent magnetization, and petrographic investigation reveal that the magnetic carrier of the Jurassic limestones is authigenic magnetite, whereas the dominant magnetic carrier of the Lower Cretaceous volcaniclastic sandstones is detrital magnetite. Our observations lead us to conclude that the Jurassic limestones record a prefolding remagnetization, whereas the Lower Cretaceous volcaniclastic sandstones retain a primary remanence. The volcaniclastic sandstones yield an Early Cretaceous paleolatitude of 55.5 degrees S [52.5 degrees S, 58.6 degrees S] for the Tibetan Himalaya, suggesting it was part of the Indian continent at that time. The size of "Greater India' during Jurassic time cannot be estimated from these limestones. Instead, a paleolatitude of the Tibetan Himalaya of 23.8 degrees S [21.8 degrees S, 26.1 degrees S] during the remagnetization process is suggested. It is likely that the remagnetization, caused by the oxidation of early diagenetic pyrite to magnetite, was induced during 103-83 or 77-67 Ma. The inferred paleolatitudes at these two time intervals imply very different tectonic consequences for the Tibetan Himalaya. Y1 - 2015 U6 - https://doi.org/10.1002/2014GC005624 SN - 1525-2027 VL - 16 IS - 1 SP - 77 EP - 100 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Huang, Wentao A1 - Dupont-Nivet, Guillaume A1 - Lippert, Peter C. A1 - van Hinsbergen, Douwe J. J. A1 - Dekkers, Mark J. A1 - Guo, Zhaojie A1 - Waldrip, Ross A1 - Li, Xiaochun A1 - Zhang, Xiaoran A1 - Liu, Dongdong A1 - Kapp, Paul T1 - Can a primary remanence be retrieved from partially remagnetized Eocence volcanic rocks in the Nanmulin Basin (southern Tibet) to date the India-Asia collision? JF - Journal of geophysical research : Solid earth N2 - Paleomagnetic dating of the India-Asia collision hinges on determining the Paleogene latitude of the Lhasa terrane (southern Tibet). Reported latitudes range from 5 degrees N to 30 degrees N, however, leading to contrasting paleogeographic interpretations. Here we report new data from the Eocene Linzizong volcanic rocks in the Nanmulin Basin, which previously yielded data suggesting a low paleolatitude (similar to 10 degrees N). New zircon U-Pb dates indicate an age of similar to 52Ma. Negative fold tests, however, demonstrate that the isolated characteristic remanent magnetizations, with notably varying inclinations, are not primary. Rock magnetic analyses, end-member modeling of isothermal remanent magnetization acquisition curves, and petrographic observations are consistent with variable degrees of posttilting remagnetization due to low-temperature alteration of primary magmatic titanomagnetite and the formation of secondary pigmentary hematite that unblock simultaneously. Previously reported paleomagnetic data from the Nanmulin Basin implying low paleolatitude should thus not be used to estimate the time and latitude of the India-Asia collision. We show that the paleomagnetic inclinations vary linearly with the contribution of secondary hematite to saturation isothermal remanent magnetization. We tentatively propose a new method to recover a primary remanence with inclination of 38.1 degrees (35.7 degrees, 40.5 degrees) (95% significance) and a secondary remanence with inclination of 42.9 degrees (41.5 degrees,44.4 degrees) (95% significance). The paleolatitude defined by the modeled primary remanence21 degrees N (19.8 degrees N, 23.1 degrees N)is consistent with the regional compilation of published results from pristine volcanic rocks and sedimentary rocks of the upper Linzizong Group corrected for inclination shallowing. The start of the Tibetan Himalaya-Asia collision was situated at similar to 20 degrees N and took place by similar to 50Ma. KW - remagnetization KW - paleomagnetism applied to tectonics KW - rock and mineral magnetism KW - India-Asia collision Y1 - 2015 U6 - https://doi.org/10.1002/2014JB011599 SN - 2169-9313 SN - 2169-9356 VL - 120 IS - 1 SP - 42 EP - 66 PB - American Geophysical Union CY - Washington ER -