桂北地下热水溶滤金矿床地质特征及成因

GEOLOGICAL FEATURES AND GENESES OF GEOTHERMAL FLUID LEACHING TYPE GOLD DEPOSITS IN NORTHERN GUANGXI

桂北原生金矿由一系列贫—少硫化物石英脉型金矿组成。经矿床地质、地球化学特征和流体包裹体、同位素多方面研究，认为桂北金矿是产于碎屑岩中的地下热水溶滤型金矿。其矿源主要来源于上地壳围岩，水源为大气降水，硫源主要来自深部（下地壳），通过深大断裂被带到成矿热液中，并混染了大量海成硫酸盐或沉积硫化物，热源由地壳增温和断裂磨擦提供。成矿流体为Ｋ＋—Ｎａ＋—Ｃａ２＋—ＳＯ２－４—Ｈ２Ｏ的低盐度、低密度稀释溶液。成矿温度以１３０～２３０℃为主，压力２３０～７００Ｐａ。成矿模式年龄约为１６６．４Ｍａ。

The primary gold deposits in northern Guangxi consist of a series of gold quartz veins. By comprehensive study on the geology, geochemical chatacteristics, fluid inclusions and isotopes etc. of the ore deposits, gold deposits in northern Guangxi are considered as geothermal fluid leaching type occurring in precambrian clastic rocks series, whose metallogenetic material mainly originates from the wallrocks of upper crust, the water source is of atmospheric precipitation, and sulpher,being brought into the hydrothermal ore-forming solution through deep fractures and contaminated a lot of marine sulfates or sedimentary sulphides, mainly comes from the deep part (lower crust). The thermal source is supplied by crustal temperature growth and fractures' rub. Metallogenetic fluid is of low salinity and density dilute solution of K +—Na +—Ca 2+ —SO 4 2- —H 2O. Metallogenetic temperature ranges from 130℃ to 230℃, and pressure from 230 to 700Pa. The age of metallogenetic model is about 166.4ma.