敖汉旗金厂沟梁金矿床地质特征及成矿时代

Geological Features and Metallogenic Time of Jinchanggouliang Gold Deposit,Aohan Banner,Inner Mongolia

金厂沟梁金矿床是华北克拉通北缘中段的一个重要的大型金矿床.本文分别对与58号脉相互穿插的黑云粗安岩和与成矿具有密切关系的对面沟花岗闪长岩复式岩株进行了定年工作.锆石LA-ICP-MS U-Pb测年结果表明,黑云粗安岩的结晶年龄为131.7±1.1Ma,对面沟花岗闪长岩复式岩株的成岩年龄为142.65±0.44～138.7±1.2Ma,由此限定金厂沟梁金矿床的主成矿期在142.7～131.7Ma之间.金矿化作用与岩浆作用同期或稍晚,由含矿热液运移富集成矿元素而成矿.该矿床为岩浆热液型金矿床,成岩成矿作用与燕山晚期中国东部发生的岩石圈减薄作用密切相关.

The Jinchanggouliang gold deposit is an important large gold deposit in the northern margin of the North China Craton （NCC）.This paper gave detailed studies on the chronology of biotite-trachyandesite veins cutting mutually with No.58 gold-ore vein and Duimiangou granodiorites,which are related to the mineralization in Jinchanggouliang gold deposit.In-situ zircon U-Pb dating was performed with LA-ICP-MS and reliable n（206pb）/n （238U） age data in fine-grained zircon were obtained.The results yield two concorde ages of 131.7 ± 1.1Ma for biotite-trachyandesite and 138.7 ± 1.2Ma ～ 142.65 ± 0.44Ma for Duimiangou granodiorites.The ages data defined the main mineralization period in 142.7 ～ 131.7Ma.Gold mineralization with the same period of magmatism or a little later,ore-forming elements enriched and mineralization by the migration of hydrothermal.Jinchanggouliang deposit is a magmatic hydrothermal gold deposit,diagenetic and mineralization in this area were related to the lithospheric thinning in Eastern China in the Late Yanshanian.