欢迎访问现代地质!

现代地质 ›› 2023, Vol. 37 ›› Issue (03): 586-598.DOI: 10.19657/j.geoscience.1000-8527.2021.149

• 岩石学与岩石地球化学 • 上一篇    下一篇

青海省海晏县团宝山一带变质岩年代学、地球化学及其地质意义

王向伟1,2(), 张保涛3(), 杨浩强3, 韩进国3   

  1. 1.山东正元地质资源勘查有限责任公司, 山东 济南 250101
    2.中国冶金地质总局矿产资源研究院, 北京 100131
    3.中国冶金地质总局山东正元地质勘查院, 山东 济南 250013
  • 收稿日期:2021-03-06 修回日期:2023-03-29 出版日期:2023-06-10 发布日期:2023-07-20
  • 通讯作者: 张保涛,男,高级工程师, 1987年出生,矿物学、岩石学、矿床学专业,主要从事矿物学、岩石学、矿床学研究。Email: zhbaotao@163.com
  • 作者简介:王向伟,男, 工程师, 1986年出生,矿物学、岩石学、矿床学专业,主要从事矿物学、岩石学、矿床学研究。Email: 476479973@qq.com
  • 基金资助:
    中国地质调查局地质调查项目(12120113033011)

Geochronology, Geochemistry and Geological Significance of Tuanbaoshan Metamorphic Rocks in Haiyan, Qinghai Province

WANG Xiangwei1,2(), ZHANG Baotao3(), YANG Haoqiang3, HAN Jinguo3   

  1. 1. Shandong Zhengyuan Geological Resources Exploration Co.,Ltd., Jinan,Shandong 250101, China
    2. Institute of mineral resources, China Metallurgical Geology Bureau, Beijing 100131, China
    3. Geological Exploration Institute of Shandong Zhengyuan, China Metallurgical Geology Bureau, Jinan, Shandong 250013, China
  • Received:2021-03-06 Revised:2023-03-29 Online:2023-06-10 Published:2023-07-20

摘要:

团宝山位于青海省海晏县,处于南祁连东段,化隆岩群发育广泛。为加深对区内变质岩及其地质意义的认识,选取变质岩新鲜样品开展年代学和地球化学研究。样品LA-ICP-MS锆石U-Pb加权平均年龄为(2047±30) Ma和(755±13) Ma,推断其成岩年龄为元古宙晚期。岩石SiO2含量平均为62%,FeO含量平均为4.79%,Fe2O3含量平均为6.44%,MgO含量平均为3.46%,稀土元素总量平均为476×10-6。稀土元素球粒陨石标准化配分曲线表现为向右倾斜,重稀土配分曲线趋于平缓,具有弱铕亏损和轻稀土富集的特征;微量元素富集Th、U、Ce、Zr、Hf等高场强元素,亏损Ba、P、Ti等亲石元素。综合年代学和地球化学特征,经原岩恢复,认为区内变质岩原岩主要为长英质砂泥岩,原岩构造环境趋向于大陆岛弧,推断该套变质岩是Rodina超大陆裂解记录的组成部分。

关键词: 年代学, 地球化学, 原岩特征, 变质岩, 团宝山

Abstract:

The Tuanbaoshan metamorphic rocks (Hualong Group) are widely distributed in eastern South Qilian (Haiyan County, Qinghai Province). To deepen our understanding on the local metamorphic rocks and their geological significance, analyses of petrography, geochronology and geochemistry were conducted on the least-altered samples. The obtained weighted average ages ((2,047±30) Ma and (755±13) Ma) indicate that the formation age is Late Proterozoic. The average chemical content of the rock: SiO2 accounts for 62%, FeO accounts for 4.79%, Fe2O3 accounts for 6.44%, MgO accounts for 3.46%, and the average total amount of rare earth elements is 476×10-6. The rocks right-inclining chondrite-normalized REE and flat HREE patterns, weak Eu anomalies and LREE enrichment. The metamorphic rocks are rich in high field strength elements (HFSEs, e.g., Th, U, Ce, Zr, and Hf), but depleted in lithophile elements (e.g., Ba, P, and Ti). Comprehensive geochronological and geochemical characteristics suggest that protoliths of the local metamorphic rocks are mainly felsic sandy mudstone, and the protolithic formation environment may have been continental arc associated with the Rodina supercontinent breakup.

Key words: geochronology, geochemistry, protolith characteristic, metamorphic rock, Tuanbaoshan

中图分类号: