LA-ICP-MS Zircon U-Pb Age and Geochemical Characteristics of Amphibolite at Qikeshan in South Altyn Tagh

被引：0

作者：

Wang L. ^{[1
]}

Zhang Y. ^{[2
]}

Yang P. ^{[1
]}

机构：

[1] MLR Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, Xi'an Center of Geological Survey, CGS, Xi'an, 710054, Shaanxi

[2] Geological Exploration Fund Project Management Center, Urumqi, 830001, Xinjiang

来源：

Geotectonica et Metallogenia | 2017年 / 41卷 / 04期

关键词：

Altyn Tagh; Amphibolite; Genesis; Geochemistry; Isotopic age;

D O I：

10.16539/j.ddgzyckx.2017.04.012

中图分类号：

学科分类号：

摘要：

The amphibolite distributes in the northwestern part of the Qikeshan hill in Altyn Tagh. Field geological investigation reveals that the amphibolite is a magmatic intrusion rather than part of an ophiolite suite. The rock have high SiO2 and Al2O3 contents of 49.29%-51.03% and 12.27%-14.49%, low Na2O+K2O content of 2.35%-4.37%, MgO and Mg# values of 6.48%-10.12% and 48.7-59.6. The rocks are enriched in LREE with negative Eu anomalies, and show linear trends on diagrams of MgO-SiO2, MgO-Al2O3, MgO-TiO2 and Rb-Cr and Rb/Zr-Rb/Nb. These show amphibolite rocks are formed by the differentiation and evolution of mantle magma. Trace elements are characterized by Rb, Th and U enrichments and Nb, Sr, P depletion. The Th/Ta (1.05-2.77) and Nb/La (0.88-1.02) values demonstrate that continental contamination is minor. Geochemical characteristics of the rocks suggest an intraplate extensional environment. LA-ICP-MS U-Pb isotopic dating of zircons yielded 206Pb/238U-207Pb/235U concordia age and 206Pb/238U weighted mean age of 503±5 Ma and 479±6 Ma, respectively. According to the Th/U ratio of zircons, we believe these ages belong to the peak metamorphic stage. In other word, it may indicate that the rocks formed before 479 Ma. © 2017, Science Press. All right reserved.

引用

页码：790 / 799

页数：9

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