辽东裂谷白云金矿载金黄铁矿Re-Os定年及其地质意义

摘要

The Baiyun gold deposit is one of the most important large gold deposits in the Liaodong rift. However, no directly chronological dating result has been reported for it yet. On purpose of dating the mineralization of the deposit, rhenium and osmium isotopes in eight gold bearing pyrite separates from different types of ores in the deposit have been analyzed. The results yielded Re-Os isochronal age of 225.3±7.0 Ma (MSWD=5.8), with an initial187Os/188Os rate of 2.1±2.8. Combined with the previous researches, it is concluded that the Baiyun gold deposit is a magmatic hydrothermal deposit, which was formed in the Indo-Sinian period and the ore-forming materials were mainly originated from the crust. It is also suggested that the deposit was formed in the intracontinental post-collisional setting subsequent to the subduction of the Mongolia-Okhtsk seas. This study may shed light on the future exploration of similar ore deposit (relate to the Indo-Sinian magmatism) in the Liaodong rift.%白云金矿是辽东裂谷区内重要的大型金矿之一,长期以来缺少直接的年代学数据。本次对白云金矿不同矿石类型中的8件载金黄铁矿进行了Re-Os同位素定年,获得其等时线年龄为225.3±7.0 Ma(MSWD=5.8),187Os/188Os初始值为2.1±2.8。结合前人的研究成果及本次年代学研究得出：白云金矿形成于印支期,其成矿物质主要为壳源,白云金矿是与印支期岩浆活动有关的热液矿床；其形成构造背景可能为受蒙古–鄂霍次克大洋向南北两侧俯冲之后的陆内后碰撞造山环境。本次研究也为今后在辽东裂谷区寻找与印支期岩浆活动有关的矿床提供了依据。