Cenozoic Vertical-Axis Rotations of the Hoh Xil Basin, Central-Northern Tibet

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• 作者：RAN Bo ; ZHAO Xixi ; LIU Zhifei ; WANG Chengshan ; ZHU Lidong ; JIN Wei and LI Yalin
• 刊名：Acta Geologica Sinica - English Edition
• 出版年：2016
• 出版时间：June 2016
• 年：2016
• 卷：90
• 期：3
• 页码：858-869
• 全文大小：8159K
• ISSN：1755-6724

文摘

Understanding the Cenozoic vertical-axis rotation in the Tibetan Plateau is crucial for continental dynamic evolution. Paleomagnetic and rock magnetic investigations were carried out for the Oligocene and Miocene continental rocks of the Hoh Xil basin in order to better understand the tectonic rotations of central Tibet. The study area was located in the Tongtianhe area located in the southern part of the Hoh Xil basin and northern margin of the Tanggula thrust system in central-northern Tibet A total of 160 independently oriented paleomagnetic samples were drilled from the Tongtianhe section for this study. The magnetic properties of magnetite and hematite have been recognized by measurements of magnetic susceptibility vs. temperature curves and unblocking temperatures. The mean directions of the Oligocene Yaxicuo Group in stratigraphic coordinates (Declination/Inclination = 354.9°/29.3°, k = 33.0, α₉₅ = 13.5°, N =5 Sites) and of the Miocene Wudaoliang Group in stratigraphic coordinates (Declination/Inclination = 3.6°/36.4°, k = 161.0, α₉₅ = 9.7°, N = 3 Sites) pass reversal tests, indicating the primary nature of the characteristic magnetizations. Our results suggested that the sampled areas in the Tuotuohe depression of the Hoh Xil basin have undergone no paleomagnetically detectable rotations under single thrusting from the Tanggula thrust system. Our findings, together with constraints from other tectonic characteristics reported by previous paleomagnetic studies, suggest tectonic rotations in the Cuoredejia and Wudaoliang depressions of the Hoh Xil basin were affected by strike-slip faulting of the Fenghuo Shan-Nangqian thrust systems. A closer examination of geological data and different vertical-axis rotation magnitudes suggest the tectonic history of the Hoh Xil basin may be controlled by thrust and strike-slip faulting since the Eocene.