湖南水口山矿区花岗闪长岩中的锆石SHRIMPU-Pb定年及其地质意义  

Zircon SHRIMP U-Pb dating of granodiorite from Shuikoushan ore-field,Hunan province and its geological significance.

作　　者：马丽艳[1] 路远发[1] 梅玉萍[1] 陈希清[1] 

机构地区：[1]中国地质调查局宜昌地质矿产研究所,宜昌443003

出　　处：《岩石学报》2006年第10期2475-2482,共8页Acta Petrologica Sinica

基　　金：中国地质调查局地质调查项目(1212010560901);国家重点基础发展规划项目(G1999043201)的部分成果

摘　　要：前人曾对与水口山矿田成矿关系密切的花岗闪长岩、花岗闪长斑岩、花岗斑岩、英安玢岩等进行了黑云母、全岩K-Ar 法和颗粒锆 U-Pb 稀释法同位素年龄测定,年龄结果介于120～172Via 之间,不同的研究者和不同的方法所测定的结果大不相同。本文对水口山矿区花岗闪长岩中的锆石进行了 SHRIMP U-Pb 年龄的精确测定,结果为163±2Ma(95%可信度,MSWD=1.2)。因此,本文认为:(J)该矿床形成于燕山早期,与华南中生代大规模的成矿作用时间一致,而且与花岗闪长岩有密切的成因联系,成岩与成矿是同时的;(2)结合岩石的微量元素地球化学特征认为,矿床是在中晚侏罗世时地壳处于拉张-减薄构造环境下形成的。Biotite and whole rock K-Ar dating and the single-grained zircon U-Pb dating for granodiorite, granodioritie porphyry, granite porphyry and dacite porphyry related to Shuikoushan ore-field have been previously reported, but different researchers and different methods give results with great difference from 120Ma to 172Ma. In this paper, we report a precise zircon SHRIMP U-Pb dating for the granodiorite in Shuikoushan ore-field of 163 ± 2Ma （95% confidence, MSWD = 1.2）. According to this new age, we suggest that： （1） this deposit formed during the early Yanshanian period, which was correspond to the large scale Mesozoic ore-forming time in South China and show a close genetic relation to the granodiorite. The rock-forming time was simultaneous to the ore formation time; （2） combined with the trace element geochemistry characteristics of the rocks, the results indicate that the deposit formed in Middle and Late Jurassic when the crust was in an extension-thinning structural setting.

关 键 词：水口山矿区 花岗闪长岩 锆石SHRIMP U-PB年龄 地质意义 

分 类 号：P597.3[天文地球—地球化学] P588.121[天文地球—地质学]