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Crustal anatexis recorded by zircon grains from early Paleozoic granitic rocks in Southeast China
Lithos ( IF 3.5 ) Pub Date : 2020-10-01 , DOI: 10.1016/j.lithos.2020.105598
Ding-Ling Huang , Xiao-Lei Wang , Xiao-Ping Xia , Feng-Feng Zhang , Di Wang , Zi-Ming Sun , Jun-Yong Li , Qing Yang , De-Hong Du , Xin Chen

Abstract Episodic granitic magmatism occurred in Southeast China from the Paleoproterozoic to the Late Cretaceous, and some of the early Paleozoic granitic rocks in the region are inferred to have formed through crustal anatexis. However, the complex processes associated with upper amphibolite-facies metamorphism and anatexis remain unclear. We investigate the early Paleozoic anatexis by analyzing zircon grains from granitic rocks in the northern Wuyi Mountains of southern Jiangxi Province. By combining mineral assemblage, field relationship, and thermodynamic modeling data with observations of zircon internal structures, we infer that anatexis occurred via partial melting of Neoproterozoic metasedimentary rocks, immediately following amphibolite-facies regional metamorphism at ca. 442 Ma (recorded by rare metamorphic zircon overgrowths around inherited cores). We identify three types of zircon grains/domains in the analyzed samples, which are related to anatectic melt migration, extraction, and eventual crystallization. Large variations in zircon Hf isotopic compositions and homogenization trends indicate that melting was heterogeneous, and homogenization of the anatectic melt occurred later. Petrogenesis of the granitic rocks, including metamorphism, disequilibrium melting, and melt accumulation, occurred over a short period from ca. 447 ± 8 Ma to 437 ± 3 Ma. We demonstrate a strong relationship between Neoproterozoic metasediments and early Paleozoic granitic rocks in Southeast China and show that homogeneous granitic plutons can form through the ‘rehomogenization’ of continental crust.
更新日期:2020-10-01
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