东昆仑东段原特提斯洋的俯冲时限:来自瓦勒尕花岗质岩石锆石U-Pb年代学及地球化学的约束  

Subduction of the proto-Tethys ocean in the eastern segment of East Kunlun:A response to zircon U-Pb geochronology and geochemistry of Walega granitic rocks

作　　者：郭香敏 丁枫[1] 凡韬 孙瑶 黄仕宗 蔺吉庆 霍艳[1] GUO Xiangmin;DING Feng;FAN Tao;SUN Yao;HUANG Shizong;LIN Jiqing;HUO Yan(College of Earth and Planetary Sciences,Chengdu University of Technology,Chengdu 610059,China;403 Geological Team,Sichuan Bureau of Geology and Mineral Exploration and Development,Emeishan 614200,China;Sichuan Ruitu Engineering Management Consulting Co.,Ltd.,Chengdu 610051,China)

机构地区：[1]成都理工大学地球与行星科学学院,成都610059 [2]四川地质矿产勘查开发局四〇三地质队,四川峨眉山614200 [3]四川睿途工程管理咨询有限公司,成都610051

出　　处：《成都理工大学学报（自然科学版）》2024年第2期222-246,共25页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：中国地质调查局地质调查项目(DD20160015-06,DD20160026)。

摘　　要：为探讨东昆仑东段早泥盆世原特提斯洋构造演化,本文对沟里地区瓦勒尕花岗质岩石进行了岩石学、锆石U-Pb年代学、地球化学等方面的研究。研究区花岗质岩石主要为二长花岗岩和花岗闪长岩,二长花岗岩锆石U-Pb年龄为414.2±2.3 Ma,花岗闪长岩的锆石U-Pb年龄为416.9±5.3 Ma。二长花岗岩和花岗闪长岩具富硅、富碱、富铝和弱过铝质特征,二者相对富集轻稀土元素,亏损重稀土元素,普遍具弱负铕异常,成因类型为I型花岗岩。研究认为,瓦勒尕二长花岗岩和花岗闪长岩为下地壳基性岩石部分熔融的产物,综合区域地质背景认为二者形成于原特提斯洋俯冲消减阶段,东昆仑地区原特提斯洋在414 Ma时尚未完全关闭。In this study,we investigated the petrology,zircon U-Pb chronology,and geochemistry of Walega granitic rocks in the Gouli area to examine the tectonic evolution of the eastern section of the East Kunlun Mountains in the proto-Tethys ocean in the early Devonian.Monzogranite and granodiorite were the primary granitic rocks in the study area,with zircon U-Pb ages of 414.2±2.3 Ma and 416.9±5.3 Ma,respectively.Both were rich in silicon,alkalis,and aluminum,and were weakly peraluminous.They were also relatively rich in light rare earth elements and depleted in heavy rare earth elements.They generally had weakly negative europium anomalies,and were classified asⅠ-type granite.The results showed that the monzogranite and granodiorite from Walega were products of the partial melting of basic rocks in the lower crust.The comprehensive geological background of the region suggested that they were formed during the subduction of the proto-Tethys ocean,which had not completely closed in the East Kunlun region in 414 Ma.

关 键 词：东昆仑造山带 原特提斯洋 花岗质岩石 岩石成因 构造背景 

分 类 号：P597[天文地球—地球化学]