云南格咱岛弧地苏嘎成矿岩体LA-ICP-MS锆石U-Pb年龄及地质意义

Zircon U-Pb age of Disuga metallogenic porphyries in Geza island arc, Yunnan Province, and its geological significance

利用锆石LA-ICP-MS U-Pb定年法对格咱岛弧中部的地苏嘎成矿岩体中不含矿和含矿2类石英闪长玢岩进行了年代学研究,获得不含矿石英闪长玢岩的形成年龄为203.03Ma±0.54Ma,含矿石英闪长玢岩的年龄分为2组217.25Ma±0.89Ma和208.5Ma±1.0Ma,限定了地苏嘎岩体的岩浆活动时限为217～203Ma,而与成矿作用相关的热液事件主要发生在208Ma。研究表明,地苏嘎成矿岩体的成岩成矿时代均发生在印支晚期,岩浆作用和成矿作用时代基本吻合,但岩浆作用的时限已接近燕山期,这对探讨格咱岛弧构造岩浆演化及成岩成矿作用的研究具有重要意义。

Using LA-ICP-MS zircon U-Pb dating method, the authors made geochronologic studies of the barren and ore-bearing quartz diorite porphyries in Disuga ore-forming intrusion of central Geza island arc. The age of barren quartz diorite porphyry is 203.03Ma_＋0.54Ma, whereas the ages of ore-bearing porphyries can be divided into two groups, i.e., 217.25Ma＋0.89Ma and 208.5Ma＋l.0Ma, which constrain the magrnatic intrusion time to 217~203Ma; nevertheless, the hydrothermal events associated with mineralization mainly occurred in 208Ma. Studies have shown that the rock-forming and metaUogenic events occurred in the late Triassic, magmatism and mineralization were basically consistent with each other,but the time of the magmatism was close to the Yan- shanian movement. All these data are of very important significance in investigating the island arc magmatic evolution and rock- forming and ore-forming activities.