Jurassic Paleomagnetism of the Lhasa Terrane—Implications for Tethys Evolution and True Polar Wander
Ma, Yiming; Wang, Qiang; Wang, Huapei; Wan, Bo; Zhang, Shihong; Deng, Chenglong; Zheng, Dongyu; Ren, Qiang; Yang, Tianshui; Wu, Dan; Zou, Di; Wang, Jun; Liu, Xiao; Kang, Zhiqiang; Dan, Wei; Han, Fei; Dekkers, Mark J.
(2022) Journal of Geophysical Research: Solid Earth, volume 127, issue 12, pp. 1 - 23
(Article)
Abstract
The drift history of the Lhasa terrane from Gondwana to Asia plays a crucial role in understanding the Tethys evolution and true polar wander (TPW). However, few reliable paleomagnetic results from Jurassic strata are currently available for reconstructing its northward journey. We performed a combined paleomagnetic and geochronological study on
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Bima Formation strata in the Xigaze area. Combined with previous results from the Sangri area, our results reveal a paleolatitude of 8 ± 4°S at ∼180 Ma for the reference point (29.3°N, 90.3°E). Along with other paleomagnetic results from the Triassic to Cretaceous, our new results suggest that the Lhasa terrane motion accelerated from ∼2 cm/yr during ∼220–180 Ma to ∼17 cm/yr during ∼180–170 Ma. Paleolatitude information of the North Qiangtang terrane and Tethyan Himalaya is calculated from paleopoles that meet five criteria, which include (a) structural control, (b) well-determined rock age, (c) stepwise demagnetizations, (d) a minimum of 25 specimens or 8 sites are contained, and (e) robust field or reversal tests are provided. Both terranes also show significant acceleration during their northward motion, which may be related to oceanic slab subduction. Thus, all Gondwana-derived microcontinents seem to share a significant acceleration during their northward motion. In addition, recent paleomagnetic results from volcanic rocks dated at ∼155 Ma subdivide the overall northward motion during ∼170–130 Ma into two stages, which include a southward drift during ∼170–155 Ma followed by northward motion during ∼155–130 Ma. These results support the fast Late Jurassic TPW during a ∼10 Myr time span.
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Keywords: northward drift, paleomagnetism, subduction, Tibetan Plateau, true polar wander, Taverne, Geophysics, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Space and Planetary Science
ISSN: 2169-9313
Note: Funding Information: We are grateful to four anonymous reviewers and associate editor Adrian Muxworthy for their constructive comments. We also thank Yongtao Li, Haiyan Li, Yingchao Xu, Zongmin Zhu, Qiang Liu, and Haijun Xu for providing laboratory instruments and Weimin Ruan, Chao Niu, Chang Xu and Peng Han for their help in the laboratory. This work is supported by the Second Tibetan Plateau Scientific Expedition and Research (STEP) (2019QZKK0702), the National Natural Science Foundation of China (41802242, 42174089, 91855215, 42021002, 41874079, and 42030205), and the Strategic Priority Research Program of Chinese Academy of Sciences (XDA2007030402, XDA17010403, and XDB41010304). Funding Information: We are grateful to four anonymous reviewers and associate editor Adrian Muxworthy for their constructive comments. We also thank Yongtao Li, Haiyan Li, Yingchao Xu, Zongmin Zhu, Qiang Liu, and Haijun Xu for providing laboratory instruments and Weimin Ruan, Chao Niu, Chang Xu and Peng Han for their help in the laboratory. This work is supported by the Second Tibetan Plateau Scientific Expedition and Research (STEP) (2019QZKK0702), the National Natural Science Foundation of China (41802242, 42174089, 91855215, 42021002, 41874079, and 42030205), and the Strategic Priority Research Program of Chinese Academy of Sciences (XDA2007030402, XDA17010403, and XDB41010304). Publisher Copyright: © 2022. American Geophysical Union. All Rights Reserved.
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