Paleomagnetic results from Late Carboniferous to Early Permian rocks in the northern Qiangtang terrane, Tibet, China, and their tectonic implications

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• 作者：XingFeng Yang ; Xin Cheng ; YaNan Zhou ; Lun Ma…
• 关键词：Northern Qiangtang terrane ; Late Carboniferous ; Early Permian ; Rock magnetism ; Conglomerate test ; Paleomagnetic pole
• 刊名：Science China Earth Sciences
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：60
• 期：1
• 页码：124-134
• 全文大小：
• 刊物主题：Earth Sciences, general;
• 出版者：Science China Press
• ISSN：1869-1897
• 卷排序：60

文摘

Results of a systematic paleomagnetic study are reported based on Late Carboniferous to Early Permian sedimentary rocks on the north slope of the Tanggula Mountains, in the northern Qiangtang terrane (NQT), Tibet, China. Data revealed that magnetic minerals in limestone samples from the Zarigen Formation (CP^z)are primarily composed of magnetite, while those in sandstone samples from the Nuoribagaribao Formation (Pnr) are dominated by hematite alone, or hematite and magnetite in combination. Progressive thermal, or alternating field, demagnetization allowed us to isolate a stable high temperature component (HTC) in 127 specimens from 16 sites which successfully passed the conglomerate test, consistent with primary remnance. The tilt-corrected mean direction for Late Carboniferous to Early Permian rocks in the northern Qiangtang terrane is D_s=30.2°, I_s=- 40.9°, k_s=269.0, α₉₅=2.3°, N=16, which yields a corresponding paleomagnetic pole at 25.7°N, 241.5°E (dp/dm=2.8°/1.7°), and a paleolatitude of 23.4°S. Our results, together with previously reported paleomagnetic data, indicate that: (1) the NQT in Tibet, China, was located at a low latitude in the southern hemisphere, and may have belonged to the northern margin of Gondwana during the Late Carboniferous to Early Permian; (2) the Paleo-Tethys Ocean was large during the Late Carboniferous to Early Permian, and (3) the NQT subsequently moved rapidly northwards, perhaps related to the fact that the Paleo-Tethys Ocean was rapidly contracting from the Late Permian to Late Triassic while the Bangong Lake-Nujiang Ocean, the northern branch of the Neo-Tethys Ocean, expanded rapidly during this time.