二密铜矿区松顶山次火山岩成矿作用及找矿方向

Metallogenesis of Songdingshan sub-volcanic rocks and prospecting direction in Ermi Copper District

二密铜矿床受控于早白垩世松顶山火山机构。为实现找矿突破,指导找矿工作,以成矿地质条件为基础,分析了火山机构内次火山岩成岩成矿作用,并对找矿方向提出了新的认识。研究表明,松顶山火山机构主要有闪长岩、石英闪长岩、石英二长闪长岩、花岗斑岩4次岩浆侵入活动,前3次均发育有主火山口相、寄生火山口相,而与铜成矿作用关系密切的花岗斑岩仅发现有寄生火山口相。结合同期次流纹岩等喷发物分布范围等实际地质资料,认为松顶山火山机构内部很有可能发育隐伏的主火山口相花岗斑岩体,应作为主要找矿方向之一。

Ermi Copper Deposit is controlled by Early Cretaceous Songdingshan volcanic organization. In order to achieve prospecting breakthroughs and instruct prospecting work,the paper analyzed the diagenesis and metallogenesis of the volcanic rocks inside the volcanic organization based on ore-forming geologic conditions,and came up with new understanding of prospecting direction. The study shows that the Songdingshan volcanic organization mainly includes 4 magmatic intrusions: diorite,quartz diorite,quartz monzodiorite and granite porphyry. The former 3 all develop main crater phase and parasitic crater phase while the granite porphyry closely related to copper mineralization only is detected with parasitic crater phase. Judging from the practical geologic data including the distribution range of the erupted materials in the same phase such as rhyolite,it is considered that it is likely that there develop concealed main crater phase granite porphyry rock mass inside the Songdingshan volcanic organization and the area should be considered as one of the major prospecting directions.