赣南银坑矿田高山角花岗闪长岩SHRIMP U-Pb定年及其与成矿的关系

高山角花岗闪长岩体位于南岭成矿带东段之北部,南岭东西向构造与滨太平洋北北东向构造带的交汇复合部位。岩体产出于银坑贵多金属矿田内部,与区内金银铅锌铜的成矿作用密切相关。在矿田地质和岩体地质工作基础上,采用SHRIMP锆石U-Pb法对高山角花岗闪长岩进行了精确定年,获得岩体锆石年龄为(160±1)Ma,并存在(422±4)Ma的捕获岩浆锆石年龄,指示岩体形成于燕山早期,而并不是以往认为的早白垩纪。结合矿床地质资料,判断矿田内的贵多金属成矿作用与高山角岩浆活动同期,与赣南地区中生代(165～150 Ma)大规模钨锡成矿作用产于同一时期、同一构造背景,同属一个成矿系列。

SHRIMP U-Pb Dating of the Gaoshanjiao Granodiorite in the Yinkeng Ore-field of the South Jiangxi Region and Its Relations to Mineralization

The Gaoshanjiao granodiorite intrusion is located in the east section of the Nanling region at the conjunction of the Nanling W-E striking structure and the Pacific Ocean rim NNE structure belt. The Gaoshanjiao granodiorite occurs within the Yinkeng Au-Ag-Zn-Pb-Cu ore-field and the magmatism is genetically related with the mineralization. This paper is based on the studies of regional geology and deposit geology, by using the SHRIMP zircon U-Pb dating method, to accurately date the Gaoshanjiao intrusion. Determination results show that the formation age of Gaoshanjiao granodiorite is (161±1) Ma, with the captured zircon age of (422±4) Ma. The Gaoshanjiao intrusion occurred in the early Yanshanian period and not the early Cretaceous period as previously reported elsewhere. According to the ore deposit geology data, it is considered that the polymetallic mineralization is simultaneous with the magmatic activity and granodiaorite forming. The magmatism and mineralization occurs in the transitioning period from the Middle Jurassic epoch to the late Jurassic epoch (J₂/J₃ transition period is 160 Ma), and may be associated with the structural dynamic mechanical background of the lithosphere large extension. The Yinkeng Au-polymetallic deposit and the same metallogenic-series with famous W deposit in southern Jiangxi Province and the metallogenic age of Au are basically concordant with that of W/Sn where the ore-forming processes are mainly concentrated in the period of 150-165 Ma.