| 福建邵武金坑金多金属矿床成矿时代 |
| Received:August 24, 2020 Revised:November 07, 2020 点此下载全文 |
| 引用本文：WU ZiLong.2021.Metallogenic age of Jinkeng gold polymetallic deposit in Shaowu City, Fujian Province[J].Mineral Deposits,40(1):19~33 |
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| 基金项目:本文得到福建省地矿局科研项目“福建省邵武市金坑地区金多金属矿成矿规律及找矿方向”（编号：2016-41）资助 |
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| 中文摘要:邵武金坑金多金属矿床为福建省近年来发现的中型金多金属矿床，位于武夷山成矿带西北部，矿体主要赋存于寒武系林田组层间破碎带中，呈似层状产出，与区内闪长玢岩脉的产状一致。为了查明邵武金坑金多金属矿床的成矿时代，运用LA-ICP-MS方法对侵位于林田组的闪长玢岩进行了锆石U-Pb定年，样品共测试12个数据点，这些206Pb/238U和207Pb/235U投点均落在谐和线上及其附近，谐和年龄为（223.4±0.7）Ma (MSWD=2.1)，判断其为矿区金多金属矿成矿年龄下限。通过对矿石中闪锌矿开展Rb-Sr法年龄测定，共测试8件符合要求的同期同源样品，获得闪锌矿Rb-Sr等时线年龄(222.7±3.4) Ma。闪锌矿成矿年龄略晚于闪长玢岩成岩年龄，二者十分接近，表明矿体可能为岩浆期后热液作用形成，成矿时间为晚三叠世，约223 Ma。武夷山成矿带西北部各矿区成矿年龄显示出分期的成矿特征：即晚三叠世—侏罗纪时期靠近福建地区，成矿年龄越老；白垩纪时期则反之，越靠近江西地区，成矿年龄越老。晚三叠世成矿一直缺少较直接的证据，本次在福建邵武金坑矿区获取的成矿年龄，是首次在武夷山成矿带西北部获得的晚三叠世成矿年龄，表明该区存在晚三叠世成矿事件。在邵武金坑及周缘地区，晚三叠世形成一个岩浆热液活动和成矿高峰期，伴随区域岩浆活动，成矿热液沿北东向断裂上升，在构造有利部位沉淀富集而成矿。 |
| 中文关键词:地球化学 金多金属矿床 成矿时代 锆石U-Pb测年 闪锌矿Rb-Sr测年 金坑 |
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| Metallogenic age of Jinkeng gold polymetallic deposit in Shaowu City, Fujian Province |
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| Abstract:The Jinkeng gold polymetallic deposit in Shaowu of Fujian Province is a medium-sized deposit discovered in recent years. It is located in the northwestern Wuyi metallogenic belt. The orebodies mainly occur in the interbedded fracture zone of Cambrian Lintian Formation and appear in bedded form, consistent with the occurrence state of diorite porphyrite veins in this area. In order to find out the metallogenic epoch of the Jinkeng gold polymetallic deposit in Shaowu, the author carried out zircon U-Pb dating of diorite porphyrite emplaced in the Lintian Formation by the LA-ICP-MS method. Samples from 12 data points were tested, with 206Pb/238U and 207Pb/235U falling on and near the concordia line. The concordia age is (223.4±0.71) Ma (MSWD=2.1), which is the lower limit of metallogenic age of gold polymetallic ore deposits. Rb-Sr method was used to get the age determination for sphalerite, and a total of 8 samples were tested, which was corresponding homologous samples. The Rb-Sr isochronal age of sphalerite is (222.7±3.4) Ma. The age of sphalerite mineralization is slightly later than but very close to that of diorite porphyrite, suggesting that the orebody was probably formed by post-magmatic hydrothermal process, which occurred in the late Triassic, about 223 Ma. The ore-forming age of each mi-ning area in the northwestern Wuyishan metallogenic belt shows the stage metallogenic characteristics:During the late Triassic-Jurassic period, the mineralization took place earlier near Fujian Province; in Cretaceous period, the mineralization took place earlier near Jiangxi Province. There has been a lack of direct evidence for late Triassic mineralization. The metallogenic age obtained this time in the Jinkeng mining area of Shaowu in Fujian is the first reliable late Triassic metallogenic age obtained in the northwest of the Wuyi Mountain metallogenic belt, which shows that there existed late Triassic metallogenic events in this area. In the Jinkeng deposit and its surrounding areas, a magmatic hydrothermal activity and the ore-forming peak took place in the late Triassic. With the regional magmatic activity, the ore-forming hydrothermal fluid migrated upward along the NE-trending faults and formed ore deposit through precipitation and enrichment at the favorable structural position. |
| keywords:geochemistry gold polymetallic ore metallogenic age zircon U-Pb dating sphalerite Rb-Sr dating Jinkeng |
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