江西广昌新安钼矿床地质特征及其铼-锇同位素测年
Geological Characteristics and Re-Os Dating of the Xin'an Molybdenum Deposit in Jiangxi Province
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摘要: 广昌新安钼矿是武夷山西坡中段新发现的斑岩型钼矿床。文章概要地介绍了该矿床的地质特征,并利用Re-Os同位素定年方法对新安钼矿体中的辉钼矿进行了成矿年代的测定,获得辉钼矿同位素的模式年龄为(166.7±2.3) Ma~(169.5±2.4) Ma,计算出等时线年龄为(168.3±1.7) Ma,表明其钼矿成矿作用发生于燕山早期,属于华南中生代大规模成矿作用第一阶段的产物。矿床成矿时代的精确厘定,说明该区在燕山期大规模钨锡成矿作用之前(165~150 Ma),可能存在一期独立的钼成矿作用。区域钼矿床年龄数据统计表明,本区至少存在三期独立的钼成矿作用,分别集中在130~140 Ma、150~160 Ma和165~170 Ma,意味着本区钼成矿作用经历了漫长的演化过程,这对区域岩浆岩活动及其成矿作用研究和找矿工作具有指导意义。Abstract: The Xin'an molybdenum deposit, located in the middle of Wuyi Mountain's western slope, is a newly discovered porphyry Mo deposit. The geological characteristics of the deposit is presented in this paper. The Re-Os model ages of the molybdenites are between (166.7±2.3) Ma and (169.5±2.4) Ma, with a calculated isochronic age of (168.3±1.7) Ma indicating that molybdenum mineralization occurred in the early Yanshanian period, belonging to the Mesozoic first large-scale mineralization. The age of this deposit indicates that a dependent Mo mineralization may have existed in this area before large-scale tungsten/tin mineralization. According to collected molybdenite Re-Os dating results, molybdenum mineralization times are mainly concentrated in Yanshanian which includes three stages of 130-140 Ma, 150-160 Ma and 165-170 Ma, meaning molybdenum mineralization is a long-term evolutionary process. This result is not only important for studying the regional magmatic activity and mineralization, but it can also guide further exploration work.
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Key words:
- Re-Os /
- isochronal /
- ages
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