内蒙古夏尔楚鲁金矿床辉钼矿铼-锇同位素年龄及成矿事件

Re-Os Isotopic Dating of Molybdenite Separated from the Xiaerchulu Au Deposit,Inner Mongolia and the Mineralization

本文为查明内蒙古四子王旗夏尔楚鲁金矿床的形成时间,对金矿体中发育辉钼矿的5件辉钼矿样品进行了铼-锇同位素分析,所获同位素等时线年龄为263.8±4.4Ma,其MSWD值为1.3.即矿体的形成时间为早二叠世,属海西期构造—岩浆作用及相关流体活动的产物.辉钼矿样品中的铼含量较低,为1.153×10^-6～2.740× 10^-6,平均为1.622×10^-6,这说明成矿过程可能与地壳重熔的S型花岗岩岩浆活动或地壳流体有关.鉴于辉钼矿呈浸染状和团块状分布于黑云母花岗岩中,并且与石英和钾长石呈共生结构关系,可以推测夏尔楚鲁金矿床和黑云母花岗岩的形成时间均为早二叠世,属海西期构造—岩浆活动的产物.

The Xiaerchulu gold deposit of Inner Mongolia located in the Ondor Sum Caledonian accretion zone in Xing＇an-Mongolia orogenic belt.The present paper is the first time to report accurate Re-Os isotopic data acquired from 5 crystals of molybdenite separated from this deposit.The Re-Os isotopic model age ranges from （260.1±3.6） Ma to （263.7±3.7） Ma and weighted mean is （261.5±1.6） Ma.The Re-Os isotopic analysis also gives an isochronal age of （263.8 ± 4.4） Ma and the MSWD is 1.3.Combined with the geological features of the deposit,the metallogenic time is Early Permian Epoch.The genesis is related closely to Hercynian tectonic-magmatic activity.