黔西南卡林型金矿床中固体有机物质的有机岩石学研究

固体有机物质保留了金属矿床成矿过程的重要信息。本文以黔西南烂泥沟和戈塘两个典型金矿床为例,系统研究了其中的固体有机物质的有机岩石学特征,并探讨了固体有机质与金矿化的关系。烂泥沟金矿固体有机质由原生煤系有机质和异源焦沥青组成。煤系有机质为原生有机质,与成岩黄铁矿关系密切,没有直接参与热液成矿作用。焦沥青沿石英脉壁粘附或在细脉和纹层中呈带状分布,是热液成矿期原油热液蚀变的产物,原油搬运Au,遭受热液蚀变并参与热化学还原,导致Au 的释放和沉淀。戈塘金矿床中有机质主要是煤系有机质碎屑,与上覆的含煤层有成因联系。这些有机质在热液过程中遭受热液蚀变,还原硫酸盐,为硫化物的沉淀提供还原硫。

ORGANIC PETROLOGICAL STUDY ON SOLID ORGANIC MATTER IN TWO CARLIN - TYPE GOLD DEPOSITS IN SOUTHWEST GUIZHOU, CHINA

Solid organic matter remained in metalliferous ore recorded important information of ore-forming processes. In this paper the Lannigou and Getang gold deposits were considered as typical Carlin-type gold deposits in Southwest Guizhou, China, with the aim to state the relationship between organic matter and mineralization based on the organic petrological study of solid organic matter (SOM) in the two deposits. SOM in Lannigou deposit consisted of coaly organic matter (maceral) and pyrobitumen. Maceral was of sedimentational-diagenetic origin and had not been involved directly in gold mineralization. Pyrobitumen was related specially to hydrothermal quartz veins and occurred as discontinuous thin membrane adhered to wall rocks or as bonded layer in veinlet. Pyrobitumen was the product of strong hydrothermal alternation of crude oil. The crude oil carried Au and consequently underwent hydrothermal alternation and participated in thermochemical reduction which leds to releasing and precipitation of Au from crude oil. SOM in Getang deposit consisted mainly of fragmental coaly inertinite which was related genetically to overlying coal-bearing formation. The SOM then suffered from strong thermal alternation and reduced sulfate to supply H 2S for precipitation of sulfides.