Episodic tectonothermal events of the western North China Craton and North Qinling Orogenic Belt in central China: Constraints from detrital zircon U-Pb ages

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• 作者：Chunrong Diwu ; ^{diwuchunrong@163.com} ; Yong Sun ; Hong Zhang ; Qian Wang ; Anlin Guo ; Longgang Fan
• 关键词：North China Craton ; Ordos block ; North Qinling Orogenic Belt ; Detrital zircon ; Episodic events ; Grenville
• 刊名：Journal of Asian Earth Sciences
• 出版年：2012
• 出版时间：30 March, 2012
• 年：2012
• 卷：47
• 期：Complete
• 页码：107-122
• 全文大小：1675 K

文摘

Detrital zircon U-Pb geochronology serves as a proxy to study of crustal evolution and provenance discrimination. In order to unravel episodic tectonothermal events and their tectonic relationship between the North China Craton (NCC) and North Qinling Orogenic Belt (NQOB), detrital zircons from modern river sands and metasedimentary rocks were collected and dated by LA-ICPMS. Although the western NCC (Ordos block) is covered by Paleozoic-Cenozoic basin sediments, the U-Pb dating results show that the age populations of detrital zircons from the western NCC present prominent U-Pb age peaks at 2475 Ma and 1850 Ma, which indicates the western NCC (Ordos block) also has early Precambrian basement similar to the eastern and central craton. In addition, a significant number of early Paleozoic (520-400 Ma) zircons have been found in the western NCC, which is quite different from the eastern NCC and is considered to be related to the collision between the NQOB and the NCC.

The age spectra of detrital zircons from the NQOB presents a complex age pattern, which reveals four major age groups of Neoarchean (2.6-2.4 Ga), Neoproterozoic (1.0-0.85 Ga), early-middle Paleozoic (450-350 Ma) and early Mesozoic (250-170 Ma). As indicated by the U-Pb isotopic data that the NQOB could be an independent terrane at least prior to the Neoproterozoic and once a portion of the Grenville orogenic belt during the 1.2-0.8 Ga with a peak of ?.0 Ga. In other words, the NQOB has its unique geological evolution history obviously different from those of the NCC and the Yangtze Craton. The complete collision between the NQOB and the NCC perhaps took place at Paleozoic (450-400 Ma).