青海祁漫塔格地区野马泉花岗闪长岩LA-ICP-MS锆石U-Pb年龄及其地质意义

LA-ICPMS zircon U-Pb age of the Yemaquan granodiorite in the Qimantag area, Qinghai Province and its geological implications

摘要: 青海东昆仑复合造山带西段的祁漫塔格地区是一个特征显著的侵入岩浆构造带，同时也是重要的多金属成矿带。野马泉铁铜多金属矿是该区较为典型的接触交代矽卡岩型矿床。利用LA-ICP-MS 锆石U-Pb 定年方法，获得该矿区与野马泉铁铜矿床有关的花岗闪长岩体的成岩年龄为226±2Ma；该结果与前人利用辉钼矿Re-Os 法获得的矽卡岩型铜钼多金属矿石和矽卡岩型钼矿石的等时线年龄一致，因此本文厘定野马泉矿区成岩成矿时代为中—晚三叠世。

Abstract: Qimantag area in the western part of the East Kunlun orogenic belt is a characteristic intrusive magmatic structural belt, and is also an important polymetallic metallogenic belt. The Yemaquan Fe-Cu polymetallic ore district is a typical contact metasomatism skarn deposit. In this study, the authors obtained the petrogenetic age of the granodiorite (226±2Ma) by using LA-ICP-MS zircon U-Pb dating. The result is in agreement with previous isochron age of 225.0±4.0Ma for skarn copper molybdenum polymetallic ore and 230.1±4.7Ma for skarn type molybdenum ore obtained by molybdenite Re-Os method. It is thus held that the petrogenetic and ore-forming epoch is Middle-Late Triassic.