塔里木盆地早古生代桑塔木组辉绿岩SHRIMP锆石U-Pb年龄及成因讨论

摘要

In addition to the main Permian magmatic activities and a few Precambrian magmatic activities occurred in Tarim Basin,there is still lack of conclusive evidence that any magmatic activities happened in other times.This paper reports SHRIMP zircon U-Pb ages of diabase from the well shunbei-1 in Upper Ordovician Sangtamu Formation of Tarim Basin.The zircon U-Pb dating show that these diabases have age of (444± 3) Ma,belonging to Upper Ordovician.In combination with seismic profiles and previous geochronology,this intrusion was considered to be the product of the mantle-derived basaltic magma intruded into the shallow level,which was resulted from the subduction and collision between West Kunlun-Altyn oceanic basin and the southern margin of Tarim plate.%在塔里木盆地除主要反映出二叠纪岩浆活动及少量前寒武纪岩浆活动之外,有无其他时代的岩浆活动仍缺乏确凿证据.笔者报道了塔里木盆地顺北1井上奥陶统桑塔木组内辉绿岩侵入体的SHRIMP锆石U-Pb定年结果,确定这套岩石的侵入年龄为(444±3)Ma,为晚奥陶世.综合地震剖面及前人年代学研究成果,认为该期侵入体的形成是晚奥陶世西昆仑-阿尔金洋盆与塔里木板块南缘俯冲碰撞触发了幔源玄武质岩浆向浅部侵入结晶形成所致.