| 云南兰坪北部铜多金属矿化区成矿流体流动与矿化分带 |
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| 引用本文： | 徐启东,周 炼.云南兰坪北部铜多金属矿化区成矿流体流动与矿化分带[J].矿床地质,2004,23(4):452-463. |
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| 作者姓名： | 徐启东 周 炼 |
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| 作者单位： | 中国地质大学资源学院,湖北,武汉,430074 |
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| 基金项目： | 本文受国家自然科学基金项目(编号:40073014)资助 |
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| 摘 要： | 通过研究白秧坪、富隆厂、吴底厂、麻栗坪、金满、科登涧等矿床和矿点的矿化脉体中黝铜矿等矿物的铅同位素组成及黝铜矿和白云石的特征元素组成，进一步探讨了成矿流体与矿化分带的关系。结果表明，黝铜矿中Cu分别与As、Sb之间的正、负相关性，白云石中Sr含量与矿床之间相对距离间正相关关系，指示成矿流体由西向东流动；矿石与盆地的中新生界沉积岩系的铅同位素组成相似。不同矿化部位矿石的铅同位素组成与逆冲推覆构造断裂主要围岩铅同位素组成之间的对应关系指示，金属组分可能主要源自盆地中的中新生界沉积岩系，成矿流体与不同围岩之间的相互作用是造成不同部位矿石铅同位素组成不同的主要原因之一。成矿流体的形成、流动和沉淀源自和发生在该区地壳浅部范围。喜马拉雅期青藏高原的隆升，造成了盆地地形西高东低，有利于形成水力梯度，驱动流体由西向东流动。流体以逆冲推覆构造断裂系统作为通道流动，有效地在更大范围内、长期或周期性地从所流经的各种岩石中萃取和迁移金属组分到合适部位富集。
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| 关 键 词： | 地球化学 流体流动 矿化分带 黝铜矿 铅同位素 矿物化学 兰坪 |
| 文章编号： | 0258-7106(2004)04-0452-12 |
Ore-forming Fluid Migration in Relation to Mineralization Zoning in Cu-Polymetallic Mineralization District of Northern Lanping, Yunnan:Evidence from Lead Isotope and Mineral Chemistry of Ores |
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| Xu Qidong and Zhou Lian.Ore-forming Fluid Migration in Relation to Mineralization Zoning in Cu-Polymetallic Mineralization District of Northern Lanping, Yunnan:Evidence from Lead Isotope and Mineral Chemistry of Ores[J].Mineral Deposits,2004,23(4):452-463. |
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| Authors: | Xu Qidong and Zhou Lian |
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| Abstract: | Controlled by thrust_nappe structures, a series of epithermal Cu_Ag_Pb_Zn mineralizations occur in northern Lanping basin, western Yunnan, forming a large number of polymetallic deposits, such as Baiyangping, Fulongchang, Wudichang, Maliping, Jinman and Kedengjian, which assume regional mineralization zoning. Pb isotope data of tetrahedrite and galena as well as chemical composition of tetrahedrite and dolemite from 21 ore veins were used to study the relationship between the ore_forming fluids and the mineralization zoning. Tetrahedrite in this area belongs to tennantite and tetrahedrite species, and a part of dolomite is of ankerite species. There exists a positive correlation between Cu and As and a negative correlation between Cu and Sb in tetrahedrites, and a positive correlation of Sr with the relative distance in dolomites, implying the migration of ore_forming fluids from the west to the east in this area. The Pb isotopic composition of the ore is similar to that of Mesozoic_Cenozoic sedimentary rocks in this basin. Pb isotopic composition variations of the ores in the west, in the middle and in the east of the orefield are somewhat similar to Pb isotopic composition variations of the wall rocks in the root zone, in the median zone and in the frontal zone of the thrust_nappe respectively. Such a consistency suggests that the metals in the ore_forming fluids mainly came from Mesozoic_Cenozoic sedimentary rocks in this basin and the heterogeneous Pb isotopic composition of the ores in different parts of the orefield was caused by the interaction between the fluids and the wall rocks. This paper discusses the sources of ore_forming fluids, the driving forces for fluid migration and the migration pathway, and also deals with the formation, migration and precipitation of the ore_forming fluids in the shallow crust of this region. Tectonic uplift of the Himalayas during the Himalayan movement caused the relief form of this basin characterized by high in the west and low in the east, which helped form the hydraulic gradient needed to drive fluid migration from west to east. The fluids moved through the fault system of thrust_nappe structures, effectively extracted metals from wall rocks, and continuously or periodically transported metals to suitable places to form ore deposits. All these factors may constitute the key steps for the metallic enrichment in this area. |
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| Keywords: | geochemistry fluid migration mineralization zoning tetrahedrite lead isotope mineral chemistry Lanping |
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