The molybdenite Re-Os dating and genesis of the Kaladawan iron deposit, Ruoqiang, Xinjiang
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摘要:
喀腊大湾铁矿是近年来在阿尔金地区发现的超大型铁矿,目前控制储量近亿吨,且该铁矿具有品位高,低硫低磷等特点。由于矿床围岩的特殊性,该矿床的成因一直存在较大争议。利用Re-Os同位素定年方法,对喀腊大湾矿体中的5件辉钼矿样品进行了成矿时代测定,获得辉钼矿Re-Os同位素模式年龄为490±11Ma,等时线年龄为481.9 ±7.6Ma。二者在误差范围内基本一致。该年龄与成矿相关岩体的SHRIMP锆石U-Pb年龄488±5Ma及479±4Ma吻合,且发现的矿体附近都有闪长岩体出露,表明成岩和成矿关系密切。结合岩石学、矿物学及年代学特征,认为喀腊大湾铁矿为矽卡岩矿床。
Abstract:The Kaladawan iron deposit was discovered in the Arkin area in recent years. It is a superlarge iron deposit with controlled reserves of nearly 100 million tons, and characterized by high grade, low sulfur and low phosphorus. Due to the particularity of the surrounding rocks of the deposit, there has been a big controversy on the genesis of the deposit. In this paper, the Re-Os isotopic dating method was used to determine the metallogenic epoch of the five molybdenite samples from the Kaladawan orebody, and the molybdenite Re-Os isotopic model age is 490±11Ma, isochron age is 481.9±7.6Ma. Both are basically consistent within the error range. The ages coincide with the SHRIMP U-Pb ages of the mineralization-related rock of 488±5Ma and 479±4Ma, and there is also diorite exposed near the orebody, which shows close relationship between petrogenesis and mineralization. Combined with petrology, mineralogy and chronological characteristics, the authors hold that the Kaladawan iron deposit is a skarn deposit.
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Key words:
- Kaladawan /
- iron deposit /
- Re-Os dating /
- deposit genesis
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图 1 喀腊大湾铁矿区域地质及矿产分布(据参考文献[21]修改)
Figure 1.
图 2 喀腊大湾铁矿矿区地质图[16]
Figure 2.
表 1 喀腊大湾矽卡岩型铁矿中辉钼矿Re-Os同位素数据
Table 1. Re-Os isotopic data of molybdenite from the Kaladawan iron deposit
编号 原样名 样重/g Re/10-6 普通Os/10-9 187Re/10-6 187Os/10-9 模式年龄/Ma 测定值 不确定度 测定值 不确定度 测定值 不确定度 测定值 不确定度 测定值 不确定度 141226-15 2601-1 0.00527 2.847 0.034 1.61 0.082 1.789 0.021 15.22 0.1 508.5 8.6 150104-6 2601-1(RE) 0.05023 2.728 0.018 1.606 0.014 1.714 0.011 14.55 0.09 507.3 6.7 150104-7 2601-2 0.05046 9.953 0.109 0.3254 0.0287 6.256 0.068 50.31 0.31 480.8 7.7 150127-20 2601-2(RE) 0.01552 9.718 0.079 0.3759 0.0219 6.108 0.05 49.19 0.31 481.5 6.8 150127-21 2601-3 0.00554 24.68 0.17 0.5867 0.0653 15.51 0.11 126.5 0.7 487.5 6.5 150327-1 2601-4 0.02025 18.65 0.13 0.3873 0.036 11.72 0.08 94.37 0.56 481.3 6.5 150104-10 2601-5 0.05022 3.943 0.031 0.2232 0.0127 2.478 0.02 20.36 0.12 491 6.8 -
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