西藏玉龙斑岩铜钼矿辉钼矿铼-锇同位素定年及其成矿学意义
Re-Os Isotopic Dating of Molybdenite from the Yulong Porphyry Copper-Molybdenum Deposit in Tibet and Its Metallogenic Significance
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摘要: 玉龙铜钼矿床是金沙江—红河斑岩铜矿带北部的一个超大型铜钼矿，也是我国目前最大的几个铜矿之一。玉龙铜矿曾经作为我国新生代最典型的斑岩铜矿，在西南三江及冈底斯斑岩铜矿带的地质找矿工作中起到了典型示范作用；但与其成矿作用有关的科学问题还尚待进行深入研究，精确的成矿时代及其成矿演化历史就是其中主要课题之一。文章对采自矿区钻孔的5件辉钼矿样品进行铼-锇同位素定年，得到的等时线年龄为（41.6±1.4） Ma。5件样品的模式年龄表明，玉龙超大型铜钼矿床成矿作用的时间跨度约为1.5 Ma，说明成矿作用是在较短时期内完成，反映了独特的成矿背景和成矿机制；成矿时代也表明玉龙铜钼矿形成于早喜马拉雅阶段变形变质造山高峰期与中喜马拉雅阶段变形变质造山高峰期之间，反映了独特的成矿背景和成矿机制。Abstract: Located in the north of the JinshajiangHonghe porphyry copper metallogenic belt, the Yulong deposit is a giant porphyry copper-molybdenum deposit. This study provides the highprecision Re-Os dating of the mineralization age. The Re-Os model ages for 5 molybdenite samples are from 39.29 Ma to 41.29 Ma. According to the best-fit calculation for 5 samples, the Yulong deposit yield an isochron age of (41.6±1.4) Ma. These data indicate that the mineralization occurred in a very short period with mineralization age span of about 1.5 Ma. And it also implies the special metallogenic environment and metallogenic mechanism of the Yulong porphyry copper-molybdenum deposit.
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Key words:
- porphyry
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