滇西兰坪盆地西缘铜矿床矿物流体包裹体研究

滇西兰坪中新生代盆地西缘发育众多的铜多金属矿床，主要以脉状或透镜状赋存于由砂岩、粉砂岩和页岩组成的含盐红色碎屑岩建造中，或产于火山岩中。本文在前人工作基础上，对区域3个代表性矿床进行了系统的矿物流体包裹体地球化学研究，结果表明：区域铜矿床矿物流体包裹体类型简单，以气液两相包裹体和液相包裹体为主；均一温度不高，显示成矿为中低温度；流体包裹体成分显示为a^＋（K^＋）＋Ca^2＋Cl^-＋SO^2-4型，表明成矿流体主要是以大气降水补给的热卤水；成矿流体气相组成主要为H2O和CO2，还原性烃类气体的存在并与氧化性气体的反相关关系显示其与盆地有机质的密切关系及在成矿过程中的重要性。结合成矿地质背景及矿物氢氧同位素的分析，认为该带中的矿床地幔物质参与成矿是次要的，成因上应为受深断裂控制的、大气降水补给的热卤水型矿床。

FLUID INCLUSION CHARACTERISTICS OF COPPER DEPOSITS ON THE WESTERN BORDER OF LANPING BASIN, YUNNAN PROVINCE

The copper deposits on the western border of Mesozoic and Cenozoic Lanping basin in western Yunnan are controlled by the Lancangjiang fault zone. The copper deposits occur not only in the clastic formations composed of sandstone, siltstone and shale,but also in intermediate-basic volcanic rocks. Vein- and lens-like copper ore-bodies mostly occur in the host rocks.The ores have very simply mineral assemblages. The copper deposits are different from the typical continental sandstone- and/of shale- type copper deposits in the world. This paper deals with fluid inclusions from the three representative copper deposits in this area based on previous studies. It is concluded that fluid inclusions are simple in type,mainly gas and liquid two-phase inclusions; the fluid inclusion homogenization temperatures are low,showing the deposits were formed at moderate-low temperatures; the fluid inclusion liquids are mainly composed of Na~(+), (K~(+)), Ca~(2+), Cl~(- )and SO~(2-)_4 suggesting that the ore-forming fluids were mainly hot brines derived from ancient meteoric waters; the gaseous fluid inclusions are mainly composed of H_2O and CO_(2), and the presence of reduction hydrocarbon gases and the negative correlations between reduction hydrocarbon gases and oxidation gases showed that the reduction hydrocarbon gases are important in the ore-forming process and related to organic matter in the basin. Considering the ore-forming geological background and the stable hydrogen and oxygen isotopic compositions, it is thought that the regional copper deposits are of meteoric hydrothermal origin,controlled by the Lancangjiang fault zone, and the ore-forming fluids are mainly hot brines derived from mete oric waters. In comparison with the deposits in the middle axis fault belts of the Lanping basin, the deposits in this district are small in scale, and the mantle liquid or magmatic liquid is not important in ore-forming processes.