吉林福安堡钼矿中辉钼矿铼-锇同位素定年及成矿作用探讨
Re-Os Isotopic Dating of Molybdenite from the Fu′anpu Molybdenum Deposit of Jilin Province and Discussion on Its Metallogenesis
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摘要: 福安堡钼矿是吉林中部地区近年来新发现的一个中型规模斑岩型钼矿，成矿地质特征与同一成矿带内的大黑山超大型钼矿相似，其深部找矿前景良好。文章首次对福安堡钼矿中5件辉钼矿样品进行铼-锇同位素测定，分析结果表明，辉钼矿中铼含量为9.94～15.12 μg/g，模式年龄为(165.3±2.4) Ma～(167.0±2.3) Ma，平均模式年龄为（166±1） Ma；等时线年龄为（166.9±6.7） Ma，其加权平均方差（MSWD）为0.60，属燕山早期成矿。成矿物质主要为壳源，但混有少量的幔源组分。燕山早期由于古太平洋板块的俯冲作用，含矿似斑状二长花岗岩侵位于北东向和北西向断裂的交汇部位，成矿物质在岩浆期后聚集形成了福安堡钼矿。燕山早期为吉黑成矿省吉中—延边（活动陆缘）成矿带钼矿的主要成矿期。加强对该地区燕山早期岩浆作用的研究，有助于地质找矿取得新的突破。Abstract: The Fu′anpu molybdenum deposit is a newly discovered medium-scale porphyry molybdenum deposit in central Jilin Province and has great potential in deep prospecting. A precise Re-Os isotopic dating for five molybdenite samples from the Fu′anpu molybdenum deposit was carried out. The Re content in the samples varied from 9.94 μg/g to 15.12 μg/gand the model age of the molybdenite from (165.3±2.4) Ma to (167.0±2.3) Ma with the average model age of （166±1） Ma and the isochron age of (166.9±6.7) Ma, MSWD=0.60. The results indicate that the mineralization in the Fu′anpu molybdenum deposit took place at the Early Yanshanian period. The comparatively low Re content shows that ore-forming materials mainly came from a crustal source. Because of the movement of Palaeo-Pacfic Plate in the Early Yanshanian period, ore-bearing granites invaded in the intersection regions of the NE and NW direction faults， and the ore formed at post magmatic stage. The Early Yanshanian period is the major metallogenic epoch of the Jizhong-Yanbian metallogenic belt of the Jilin-Heilongjiang metallogenic province. Study on the magma intrusion at Early Yanshanian period in this region is of important significance for further prospecting of molybdenum ore.
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Key words:
- the /
- Fu′anpu /
- molybdenum /
- deposit /
- porphyry
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