LA-ICP-MS U-Pb Geochronology, Geochemistry and Petrography of Akebulake Pluton in Southern Altay Orogenic Belt: An Example for Magma Mixing

被引：1
|
作者：
Lin X. [1 ]
Zhang Y. [1 ]
Chen G. [2 ,3 ]
Guo Q. [1 ]
Wang X. [1 ]
Zhao D. [1 ]
机构：
[1] Shaanxi Mineral Resources and Geological Survey, Xi’an
[2] School of Civil Engineering, Nanyang Institute of Technology, Nanyang
[3] Key Laboratory of Western China’s Mineral Resources and Geological Engineering, Ministry of Education, Chang’an University, Xi’an
来源：
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | 2023年 / 48卷 / 10期
关键词：
Akebulake pluton; altay; geochemistry; LA-ICP-MS zircon U-Pb age; mafic microgranular enclave; magma mixing; petrology;
D O I：
10.3799/dqkx.2021.215
中图分类号：
学科分类号：
摘要：
The Akebulake pluton in the southern margin of the Altay orogenic belt is composed of tonalite, dioritic microgranular enclaves and mafic dikes. The pluton exhibits excellent evidence for magma mixing and mingling, such as the feldspathic phenocryst, long prisms of apatite in enclaves and quartz, plagioclase wrapped in biotite in the host rock. Host rocks, dioritic microgranular enclaves and mafic dikes of the Akebulake pluton are products of mixing with different end element ratios in the process of magma mixing evolution. LA-ICP-MS zircon U-Pb dating from three samples yielded weighted mean 206Pb/238U ages of 396.3±3.3 Ma, 392.2±3.7 Ma and 402.3±3.3 Ma, respectively. It indicates that they were formed in the same magmatic event, which provides important chronological evidence for the genesis of magma mixing of Akebulake pluton. Geochemically, the major oxide content of the mafic dikes, dioritic enclaves and their host rocks all have a good linear relationship in the plot, and the patterns of REE, spidergrams of trace elements of the dioritic enclaves and mafic dikes are similar to those of the host granites, suggesting that component exchange and homogenization occurred between the enclaves and the host rocks in the process of rock formation. Hf isotopic composition of zircon is not uniform. The host rocks, enclaves and mafic dikes εHf(t) vary from 1.22 to 4.70, -3.49 to 7.41 and 3.65 to 9.02, respectively. The Hf isotopic model ages (tDM2) range from 962 to 1 131 Ma, 816 to 1 375 Ma and 740 to 1 015 Ma, respectively. Based on a comprehensive analysis with the data of southern margin of Altay, the authors hold that the dioritic enclaves in the Akebulake pluton were generated by mixing of mantle-derived mafic magma and its induced crustal felsic magma in an island-arc setting of active continental margin. The formation of magma mixing of the Akebulake pluton further confirms that strong crust-mantle magmatic mixing occurred in the deep crust of the southern margin of the Altay orogenic belt during the Early Devonian, which resulted in an important event of lateral continental crust growth at the syn-accretionary stage in Altay. © 2023 China University of Geosciences. All rights reserved.
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页码：3597 / 3612
页数：15
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