桂西北高龙式金矿的成矿机理研究

THE STUDY ON METALLOGENY OF GAOLONG GOLD DEPOSIT, NORTH WEST GUANGXI

本文对桂西北典型的微细浸染型金矿床的代表之一——高龙金矿床产出的地质背景作了说明,对该金矿床的矿区地质、矿体形态与规模、矿石类型及矿物共生组合特征等进行了较为详细的描述,对高龙式金矿床氧化机理的室内研究及其实验测试结果从矿区矿体的地球化学特征角度进行了分析,提出了高龙式金矿床氧化矿体的成因模式,认为:在中三叠时期形成的桂西北微细浸染型金矿床,系由水下岩浆的大量喷出沉积的火山物质,经成岩作用和地下热液不断淋滤淬取围岩物质而形成的矿床。金主要以徽细浸染的形式赋存于各种硫化物中。由内生成矿作用形成的原生矿体,由于构造运动的影响而暴露地表后,受温度、水,CO_2、pH、Eh值、氧化铁疏杆菌等的影响,含金硫化物的结构遭到严重破坏,形成地表条件下可稳定存在的氧化物类及氧化矿体。桂西北中三叠系氧化带中的高龙金矿属—成矿循环周期中晚期阶段的产物。

In northeast district of Guangxi,China,the micro-fine grain dissiminated type gold deposit is commonly distributed. Gaolong is one large scale gold deposit,which lies in the oxidization zone. The area lies in the south-eastern dectivity zone of Yun-Gui plateau. According to the deposit's geological characters, mineral's combination type and forming characters,the micro-fine grain dissiminate type gold deposits can be divided into two types as Gaolong and Jinya.Gaolong type gold deposit is mainly distributed in oxidized zone (weathering belt). In the area,only oxidized ores are found, noevidence of primery sulfide ores. All bodies were yielded in oxidized zone. At the lower part of the orebody, only nonoxidized structured quartzite ore bodies be found. According to ore type,three types of ore bodies can be divided as follow:a Texture quartzite type ore(keatite rock);b siliceous texture brecciated ore;c siliceous crushed crag ore.Two experiment were done to know how oxidation effect original minerals under the dif-firent pH,teperature and bacterium.Two types of the minerals can be devided into oxidized minerals and primary mineral (including pyritoides mineral, pyrite-arsenical type mineral, arsenical pyrite type mineral) According to the characteristics of the mineral's genesis and the mineral's paragenesis,we consider that Gaolong gold deposit is post-product in a cycle of metallogenetic epoch.