标题：Ca. 815 Ma intra-plate granitoids and mafic dykes from Emeishan pluton in the western Yangtze Block, SW China: A record of rifting during the breakup of Rodinia

入藏号：WOS:000796581800001

中国科学院文献情报中心期刊分区：地球科学2区/TOP（2022）

本校作者：邹灏，李阳，黄长成，蒋修未，刘行，李敏，陈海锋，刘春梅

来源出版物：PRECAMBRIAN RESEARCH  卷: 371  文献号: 106569 

出版年：2022

第一地址：成都理工大学

关键词：罗迪尼亚超大陆，峨眉山杂岩，裂解，U-Pb锆石年龄，Hf-O同位素

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摘要：The western Yangtze Block, South China is characterized by voluminous Neoproterozoic extension-related volcano-sedimentarysequences and intrusions (e.g. Emeishan granitoid intrusion) and spatially associated mafic dykes. The origin and tectonic setting of Emeishan granitoid intrusion and mafic dykes in the Yangtze Block is poorly study. Understanding the origin and geodynamic setting of dykes and granitoid intrusion are significant in deciphering thermal structure and composition of mantle, tectonic evolution as well as crustal growth processes in the Yangtze Block. SIMS Zircon U–Pb dating of Emeishan granitoid intrusion and mafic dykes suggests that the granitoids (ca. 818 Ma) and mafic dykes (ca. 814 Ma) are contemporaneous. Compositionally, the Emeishan granitoids are restricted and characterized by high SiO2 (69.11–70.50 wt%), Na2O + K2O (3.52–4.13%) and Al2O3 (14.16–14.47%), but low CaO (1.78–2.03%), MgO (0.72–0.91%) contents. They feature strong LREEenrichment(La/YbN = 7.2–12.3) in conjunction with negative Eu anomalies. The mafic dykes have low SiO2 (48.09–48.65 wt%), K2O (1.94–2.12 wt%) and Na2O (1.64–1.75 wt%) contents, and high Mg# (61.67–62.26). On primitive mantle-normalized trace element plot, they are characterized by enrichment of LILEs and depletion of HFSEs. Both the mafic dykes and granitoids record similar zircon εHf(t) values (+2.2 to +12.1, +1.4 to +6.8), and zircon δ18O values (4.47‰ and 10.41‰, 4.49‰ and 12.05‰, respectively). The rifting-related geochemical signature of the Emeishan pluton and contemporaneous margin and intra-plate plume-related magmatism suggest that they were derived from mantle melting in extensional tectonic setting during mid-Neoproterozoic.

文章链接地址:https://doi.org/10.1016/j.precamres.2022.106569