编号：CDUT-2023-17

标题：Origin and tectonic implications of the early Middle Triassic tuffs in the western Yangtze Craton: Insight into whole-rock geochemical and zircon U-Pb and Hf isotopic signatures

入藏号：WOS:000634530100004

中国科学院文献情报中心期刊分区：地球科学1区/TOP（2021年升级版）

本校作者：李文杰；施泽进^*；尹观；田亚铭；王勇；张瑾

来源出版物：GONDWANA RESEARCH  卷: 93  页: 142-161 

出版年：2021

第一地址：成都理工大学

关键词：Tuff；Tectonomagmatic event；Eastern Paleo-Tethys；Middle Triassic；Yangtze Craton

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摘要：The tuff layer steadily distributed in the western Yangtze Craton is a regional marker for the Early–Middle Triassic(Olenekian–Anisian) boundary. Integrated studies of whole-rock geochemistry and zircon geochronology revealthat the parental magma of the tuff is of felsic composition, generated via volcanic eruptions in the continental arcsetting along the southwestern margin of the Yangtze Craton at ~247 Ma. The syn-depositional zircons in the tufflayers and in the coeval igneous rocks exhibit uniform negative εHf(t) values of approximately −20 to −6, indicating the significant input of crustal materials. Massive crustal assimilation implies a large-scale remelting of thepre-existing continental crust, triggered by the intensive arc–continental collision during that time. This intensivecollisional tectonomagmatic event is an important signal for the closing of the eastern Paleo-Tethys branch andpoints to the initial collision of the Indochina Block and the Yangtze Craton. Xenocrystic zircons in thePrecambrian-age offer insight into the early evolution of the southwestern Yangtze Craton, which shows episodiccrustal growth and reworking of ~2.9–2.2 Ga, crustal reworking of ~1.9–1.7 Ga, rifting-related tectonomagmatismof ~1.6–1.4 Ga, and crustal growth of ~1.1–0.8 Ga. The older crystallization ages (3.4–2.5 Ga), lower initial 176Hf/177Hf values (0.2805–0.2813), negative εHf(t) values (−15.7 to −1.6), and two-stage Hf model ages(3.9–2.8 Ga) of zircons further suggest that an unexposed Archean basement exists beneath the southwesternYangtze Craton. Significant contributions of mantle-derived materials occur at ~1.3–1.0 Ga, implying that thesouthwestern Yangtze Craton may not be involved in the Grenvillian-aged continental–continental collisionorogeny. Comparable age spectrums and Hf isotopic data suggest that the Paleoproterozoic igneous rocks are anon-negligible provenance for Proterozoic metasedimentary in the Kangdian region

文章链接地址: https://www.sciencedirect.com/science/article/pii/S1342937X21000502