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Paleolatitudes of the Tibetan Himalaya from primary and secondary magnetizations of Jurassic to Lower Cretaceous sedimentary rocks

  • 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 aThe 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.show moreshow less

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Author:Wentao Huang, Douwe J. J. van Hinsbergen, Mark J. Dekkers, Eduardo Garzanti, Guillaume Dupont-Nivet, Peter C. Lippert, Xiaochun Li, Marco Maffione, Cor G. Langereis, Xiumian Hu, Zhaojie Guo, Paul Kapp
DOI:https://doi.org/10.1002/2014GC005624
ISSN:1525-2027 (print)
Parent Title (English):Geochemistry, geophysics, geosystems
Publisher:American Geophysical Union
Place of publication:Washington
Document Type:Article
Language:English
Year of first Publication:2015
Year of Completion:2015
Release Date:2017/03/27
Volume:16
Issue:1
Pagenumber:24
First Page:77
Last Page:100
Funder:U.S. NSF Continental Dynamics [EAR-1008527]; Netherlands Organization for Scientific Research (NWO); ERC [306810]; Alexander von Humboldt foundation; Cai Yuanpei program of the French ministries of foreign affairs; Cai Yuanpei program of the French ministries of higher education and research; Chinese ministry of education
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Erd- und Umweltwissenschaften
Peer Review:Referiert