西南三江新生代矿集区的分布格局及找矿前景

Cenozoic Ore Concentration Areas in the Sanjiang Region, SW China: Tectonic Setting and Exploration

西南三江地区是我国最重要的新生代成矿区 (带 ) ,其中分布着一系列各具特色的矿集区 ,如以铜多金属为主 (玉龙 ) ,以铅锌为主 (金顶 ) ,以稀土为主 (牦牛坪 ) ,以金为主 (哀牢山 )等等。研究中在对这些矿集区的基本特点进行归纳的基础上 ,探讨了矿集区分布的基本格局 (即两横两纵两斜加一点 )及其构造背景 ,认为进入新生代以来 ,中国经历了“东降西隆”的构造大反转 ,而三江正好位于枢纽部位 ,地壳块体水平方向强烈的挤压和垂直方向活跃的运动可能是制约三江地区地质构造和成矿格局的主要原因。在此基础上 ,提出了 3个可以扩大远景的矿集区和 3个潜在的矿集区 。

The Sanjiang (Nujiang River, Lanchangjiang River and Jinshajiang River ) region in SW China is the most important Cenozoic metallogenetic belt in China, where ore concentration areas are widely distributed. For example, the largest Cu deposit in China is located in the Yulong ore concentration area, the largest Pb-Zn deposit in China occurs in Jinding area, the second largest REE deposit in China is situated in Maoniuping area, the largest blue asbestos deposit in China lies in the Dali-Yao'an area, and the largest coal deposit in South China rests in the Zaotong area. Generally, all of these areas show a distribution pattern of 'two horizontal, two vertical, two diagonal and one spot' model. Such a distribution model is consistent with the regional tectonic setting. During Cenozoic, the Chinese earth crust changed greatly, characterized topographically by thickening in the southwest and thinning in the east or uplifting in the west and depressing in the east. Located in the central part of South China, the Sanjiang region was subjected to strong horizontal squeeze from different directions and was attacked by mantle materials and affected by heat and fluids from mantle source, resulting in the formation of complex tectonic setting and a lot of ore concentration areas. Among the nine mature ore concentration areas, three developing areas and three potential areas are delineated. Besides, this paper has put forward some views for further prospecting work in the Sanjiang region, for example, Pre-Cenozoic deposits, especially massive sulfide deposits, could be exposed to surface by large scale slip, shear or thrust structures, and geological fluids could precipitate mantle-source metals in Cenozoic basins along marginal deep faults.