摘要
东准噶尔带阿尔曼太蛇绿岩是中亚造山带南部的重要构造单元,记录了古亚洲洋的演化,但其时代一直是学术界争论的焦点问题之一。本文报道阿尔曼太蛇绿岩中斜长花岗岩锆石SHRIMPU-Pb年龄。9组测试数据给出了较好的206Pb/238U年龄503±7Ma(MSWD=1.2)。结合相关大地构造解剖与前人的年龄数据,本文认为阿尔曼太蛇绿岩是古亚洲洋在晚寒武世-早奥陶世的残余,与岛弧火山岩组成洋内弧。该洋内弧向北拼贴到阿尔泰地体南缘,形成科迪勒拉型俯冲边缘。东准噶尔带是阿尔泰南缘在古生代向南增生的弧碰撞-增生造山带,对大陆侧向增生具有重要意义。
We present a new analysis and interpretation of the geological and tectonic history of the Chinese East Junggar orogenic belt together with new, structural observations, geochronological and geochemical data. The northerly-distributed Armantai ophiolite shows mainly E-MORB and island arc-basah geochemistry, and a plagiogranite from the ophiolite yields a new SHRIMP zircon age of 503 -＋ 7 Ma. These juxtaposed tectonic units indicate multiple subduction-accretion systems amalgamated by subsequent oblique convergence, including remnants of island arc, subduction complexes, seamount and ophiolites, forming an enlarged Cordilleran-type margin by Mid-Carboniferous time. This scenario has wide implications for the architecture and crustal growth of Central Asia.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2006年第1期32-37,共6页
Acta Geologica Sinica
基金
国家重点基础研究发展规划项目(编号2001CB409801)
国家重点攻关项目(编号96-915-07)
香港研究基金项目(编号HKU7040/04P)资助成果
