博格达裂谷闭合和区域隆起的同位素年代学证据及地质意义  

Isotopic Chronologic Evidence of Bogda Rift Closure and Regional Uplift and Its Geological Significance

作　　者：王银喜[1,2] 顾连兴[2,3] 张遵忠[2,3] 张开均[2,4] 李惠民[1,2] 吴昌志[2,3] 杨杰东[1,2] 

机构地区：[1]南京大学现代分析中心,江苏南京210093 [2]南京大学内生金属矿床成矿作用国家重点实验室,江苏南京210093 [3]南京大学地球科学系,江苏南京210093 [4]中国科学院广州地球化学研究所,广东广州510640

出　　处：《地球学报》2005年第B09期102-104,共3页Acta Geoscientica Sinica

基　　金：本文为国家自然科学基金项目（编号：40472042,40072075）;国家重点基础研究发展规划项目（编号：2001CB409802）;国家“九五”攻关305项目（编号：96-915-05-03-01）和中国百人人才计划（CAS Hundred TalentsProject）合作研究成果,并得到南京大学开放测试基金（编号：0303Y302-2004）资助.

摘　　要：博格达造山带位于准噶尔和吐鲁番-哈密两个前寒武纪地块之间，是晚古生代的大陆裂谷。经研究，博格达大石头-色皮口地区的流纹岩Rb-Sr同位素年龄为307．1±1．3Ma，表明博格达地区火山活动由早石炭世持续到晚石炭世。该年龄可视为博格达裂谷闭合和区域隆什之后造山阶段产物的形成年龄。该区流纹岩其源区物质主要来自于亏损地幔或是由玄武岩浆演化经分离结晶作用形成的流纹岩这一特征是十分罕见的。The Bogda Mountain, with Junggar basin on the north and Turpan-Hami basin on the south, is a part of the East Tianshan Mountains. The Rb-Sr isotope age and the ^86Sr/^88Sr ratio of ten rhyolite samples from the Dashitou-Sepigou belt are 307.1 ± 1.3 Ma and 0. 703296 ± 32, respectively. The age data indicate that the volcanic activities of Bogda area lasted from Early and Middle Carboniferous to Late Carboniferous, and also imply that the age can be regarded as the age of Bogda rift closure and regional uplift. Sr isotopes of the rhyolites suggest that the volcanic rocks were chiefly derived from the depleted mantle source. Such a characteristic of rhyolites is very rarely seen.

关 键 词：大石头-色皮口流纹岩 Rb-Sr地质年代学 Sr同位素地球化学 裂谷闭合和区域隆什 大陆裂谷 同位素年代学 地质意义 闭合 同位素年龄 证据 

分 类 号：P542.3[天文地球—构造地质学] P597[天文地球—地质学]