矿物尺度下烃类气体的赋存特点与地质意义

Occurrence characteristics and their geological significances of the hydrocarbon gas at mineral scale

以山东焦家金矿I号主矿体为研究对象,选取128线金矿体周围不同地质体岩石样品,对样品中疑似碳酸盐矿物,通过岩矿鉴定、激光拉曼、电子探针等方法进行分析,从矿物尺度对烃类气体的赋存特点进行研究,以期获取烃类气体参与成矿的直接证据。研究发现,样品中的疑似碳酸盐矿物电子探针测定成分与纯净的方解石成分吻合,在金矿体周围不同地质体中均可见方解石以极细小的颗粒充填于矿物裂隙或矿物颗粒之间形成细脉,具有后期形成的特点;其次,电子探针数据与酸解烃法得出的烃类气体含量整体呈现出一致的变化关系,具向外渗滤扩散的特点。研究证实了疑似碳酸盐矿物确实为碳酸盐矿物,且其为烃类气体的赋存提供了载体,找到了烃类气体参与成矿在矿物尺度上的直接的证据,同时证明了酸解烃法能够有效提取与成矿有关的烃气信息,对寻找金属矿床具有一定的指导作用。

The No.I ore body of the Jiaojia Gold Mine in Shandong Province is taken as the research object in this paper.Rock samples of different geological bodies around gold ore body on the Line 128 are selected for analyzing the suspected carbonate minerals in samples using methods of rock and mineral identification,laser Raman analysis and electron probe analysis,to study the occurrence characteristics of hydrocarbon gases at mineral scale in order to obtain direct evidence of the hydrocarbon gas involvement in mineralization.It has been found that compositions of suspected carbonate minerals in samples analyzed using EPMA are coincided with that of pure calcite.In different geological bodies around the gold ore body,calcite occurred as very fine particles filling in mineral fissures or as veinlets filling in pores between mineral particles,indicating characteristics of later stage formation.In addition,contents of the hydrocarbon gas obtained by using EPMA analysis are generally consistent with those obtained by using the acid-hydrolyzed hydrocarbon method.The hydrocarbon gas has characteristics of outward infiltration and diffusion.This study has confirmed that the suspected carbonate minerals in samples are indeed carbonate minerals which had provided carriers for hosting hydrocarbon gases.The direct evidence for the involvement of hydrocarbon gases in the gold mineralization at mineral scale has been found.At the same time,it is proved that the acid-hydrolyzed hydrocarbon method can be used to effectively extract hydrocarbon gas information related to the gold mineralization and can be certainly used for guiding the exploration of metal deposits.