西部华夏地区深部可能存在与华北和扬子大陆相似的太古代基底

西部华夏地区深部可能存在与华北和扬子大陆相似的太古代基底

郑建平1, 2，Griffin WL2，汤华云1，张志海1，苏玉平1，刘观亮3

1. 中国地质大学地球科学学院，地质过程与矿产资源国家重点实验室，武汉 430074；2. GEMOC ARC National Key Centre, Macquarie University, NSW 2109, Australia；3. 宜昌地质矿产研究所，湖北宜昌 433003

收稿日期:2008-12-20 修回日期:2008-12-20 出版日期:2008-12-20 发布日期:2008-12-20

Archean Basement Similar to the North China and Yangtze Continents May Be Existed beneath the Western Cathaysia

ZHENG Jian-ping1, 2, WL Griffin2, TANG Hua-yun1, ZHANG Zhi-hai1, SU Yu-ping1, LIU Guan-liang3

1. Faculty of Earth Sciences, State Key Laboratory of Geological Processes and Minetal Resources,China University of Geoscinces, Wuhan 430047, China;2. GEMOC ARC National Key Centre, Macguarie University, NSW 2109, Austrralia;3. Yichang Institute of Geology and Mineral Resources, Yichang 443003, China

Received:2008-12-20 Revised:2008-12-20 Online:2008-12-20 Published:2008-12-20

摘要/Abstract

摘要： 华夏地区是否存在古陆是一个长期争论的问题。火山作用的天然超深钻取样，提供了探索大陆基底属性和形成演化过程的重要手段。西部华夏地区地表所出露的最古老岩石不老于中元古代，但对广西省东南部晚中生代—新生代火山岩中锆石捕虏晶的U-Pb年代学和Lu-Hf同位素研究则表明：与华北和扬子大陆相似，西部华夏地区有未暴露的太古代基底。该基底的主体年龄是2.9~2.5 Ga，也有3.85 Ga，3.55 Ga和3.3~3.2 Ga的年龄等。它们的亏损地幔模式年龄（t DM）为2.5 Ga至≥3.9 Ga。说明西部华夏地区的基底经历了复杂的改造过程，包括3.6~3.2 Ga，2.5 Ga，1.0 Ga和0.5 Ga时的地幔物质加入，以及2.0~1.8 Ga和1.6~1.5 Ga时的地壳再熔融事件等。对西部华夏地区强烈改造岩石圈的认识，将有助于从物质组分角度对华南成矿作用背景的思考。

Abstract: The oldest rocks exposed on the western Cathaysia Block in southeastern (SE) China are younger than Mesoproterozoic.However, the U-Pb and Hf-isotope systematics of xenocrystic zircons, brought to the surface by the Mesozoic-Cenozoic basaltic rocks in Guangxi Province, suggest the presence of unexposed Archean basement, with zircon populations of 3.85 Ga, 3.55 Ga,3.3~3.2 Ga and mainly 2.9~2.5 Ga and Hf model ages (t DM) of 2.5 Ga to ≥3.9 Ga, beneath the western Cathaysia Block. This basement experienced complex modification through time, including the addition of juvenile mantle material at ca 3.6~3.2 Ga, 2.5 Ga, 1.0 Ga and 0.5 Ga. The zircons also record thermal events that reworked (remelted) the older crust of the block at ca 2.0~1.8 Ga and 1.6~1.5 Ga.

郑建平, ，Griffin WL，汤华云，张志海，苏玉平，刘观亮. 西部华夏地区深部可能存在与华北和扬子大陆相似的太古代基底[J]. J4.

ZHENG Jian-ping1, 2, WL Griffin2, TANG Hua-yun1, ZHANG Zhi-hai1, SU Yu-ping1, LIU Guan-liang3. Archean Basement Similar to the North China and Yangtze Continents May Be Existed beneath the Western Cathaysia[J]. J4.