兰坪盆地三类主要铜银多金属矿床的稳定同位素地球化学

通过对兰坪盆地内三种主要成因类型（沉积-热液改造型、热水沉积-热液改造型和热液脉型）的铜银多金属矿床硫、碳、氢、氧同位素的研究,揭示了成矿作用过程的某些重要信息：矿石中的硫主要来自细菌还原的海水硫酸盐,但在沉积-热液改造型矿床中可能还有部分有机生物硫和深源火山硫的贡献;碳主要来自不同比值水/岩反应体系中碳酸盐岩地层的溶解结果,但在沉积-热液改造型矿床中还可能有深部地幔去气作用带来的CO2.成矿流体系以大气降水为主要补给源的盆地建造水,盆地建造水的运移成矿过程中可能伴有较为明显的蒸发作用.

Stable Isotopic Geochemistry of Three Major Types of Cu-Ag Polymetallic Deposits in the Lanping Basin, Yunnan

Study on sulfur, carbon, hydrogen, and oxygen isotopic geochemistry of three major genetic types (e. g., sedimentary-hydrothermal reworked, sedimentary exhalative-hydrothermal reworked, and hydrothermal veins) of Cu-Ag polymetallic deposits in the Lanping basin has provided some useful genetic information for the ore mineralization. It is indicated that sulfur in the ores was mainly derived from bacterial reduced marine sulfates, although partial contribution of organic biogenic sulfur and volcanic sulfur may be also included in the sedimentary-hydrothermal reworked deposits. Carbon in the ores was mainly from the dissolution of carbonate rocks in hydrothermal systems with different water/rock ratios, though partial CO_2 in the fluids may be contributed by deep mantle degassing. The ore-forming fluids are mainly basinal formation water recharged by meteoric water. It is implied by the positive correlation between hydrogen and oxygen isotope compositions that evaporation may have occurred during the transportation of the basinal formation water.