摘要
西昆仑—喀喇昆仑位于西藏高原西北,西构造结(Western Syntaxis)的东侧,是当前国际地学界关注的热点地区之一。本文不准备对该地区岩石圈结构、演化及其多重效应作全面论述,仅以近年青藏高原项目实施中涉及的几个较重要问题作探讨;经过对已获得的地震深探测和地质、地球化学资料的分析研究,提出青藏高原西北缘不存在塔里木向西昆仑山作长距离的“A 型俯冲”,晚新生代以来岩石圈“面对面水平挤压—拆沉作用”是形成西昆仑陆—陆碰撞造山带的主要原因。对众所关注的库地蛇绿岩形成时代,提出了新的 SHRIMP-Ⅱ,U-Ph 锆石测年年龄,上限为510±4Ma;对原特提斯大洋、康西瓦大型走滑断裂带的形成、演化作了探讨。
The West Kunlun and Karakorum Mountains are located on the northwestern side of the Tibet plateau, the eastern flank of the 'Western Syntaxis' of the Tibet plateau, which are the study hot-point for the geoscientists in the world. No evidence from the recent deep seismic experiments as well as geochemical and surface geological data support a long distance 'A type' southward subduction of the Tarim block beneath the west Kunlun Mountains. The tectonic interaction between the Tarim block and the west Kunlun block was chiefly affected by a 'horizontal compression in opposite directions ', which brought about 'face-to-face contact' between these two lithospheric blocks and led to the thickening, shortening and densifying of the lithosphere since the late Cenozoic, Hence a 'delamination' was formed due to the gravitational instability created by the thickening and densifying. The discussions about the Kudi ophiolite mainly focus on the judgment of its timing and genetic environment, this paper reports the recent ziron SHRIMP-II dating of quartz gabbro in the Kudi ophiolite (which yields an age of 510±4Ma) and its tectonic significance. A brief approach to the formation and the tectonic evolution of the Protero-Tethy and Kanxinwar strike-slip also discussed.
出处
《地质论评》
CAS
CSCD
北大核心
2004年第3期285-294,共10页
Geological Review
基金
国土资源部中国地质调查局项目(编号2003300059)
国际合作与科技司项目(编号2001010255
2001010201)以及新疆"三○五"项目
国家自然科学基金(编号96-915-01-01)
关键词
岩石圈结构
演化
青藏高原
新疆
走滑断裂带
tectonic evolution
West Kunlun Mountains
Karakkunlun Mountains
Xinjiang
