山东三甲金矿床控矿构造特征及深部预测

Features of Ore-Controlling Structure and Prediction of Mineralization at Depth in the Sanjia Gold Deposit,Shandong Province

三甲金矿床位于胶东半岛东部的牟乳金矿带内岔河—三甲断裂的南端,其围岩主要为古老变质岩和昆嵛山花岗岩,为含金石英脉型金矿。本文通过对矿床控矿构造空间形态、活动期次、力学性质以及围岩蚀变等方面的研究,认为三甲金矿主要受控于主断裂,其内不同期次的次级断裂控制了矿体的空间产出位置;控矿断裂至少经历了三期应力改造,早期为压扭兼张扭性的右行剪切变形,中、晚期以张性裂隙为主-形成多金属硫化物石英脉,后期为压扭性裂隙内部充填形成石英+碳酸盐+多金属硫化物。进而总结了矿体在断裂带中分布的规律性。深部地球化学研究表明,三甲金矿的矿石类型、矿石矿物组合具有垂向分带的特征,矿物组合逆向分带与地球化学原生晕所指示的深部成矿叠加相一致。结合矿体在断裂中分布的规律以及原生晕特点,推断三甲金矿在-506m标高以下尚有成矿富集段的存在,此次研究为深部找矿提供了重要的依据。

The Sanjia gold deposit,of the quartz vein gold type,lies at the southern end of the Chahe-Sanjia fault in the Mouping-Rushan gold ore belt in eastern Shandong,Its country rock is mainly composed of ancient metamorphic rocks and Kunyushan granite. This work has studied the spatial form,activity periods,dynamic characteristics and wall rock alteration of the Sanjia gold deposit. It was pointed out that this gold deposit was controlled by the major fault （Chahe-Sanjia） and its secondary faults which determine distribution of ore bodies. The ore-controlling fault zone had undergone three periods of deformation by stress：dextral compressive shear with tensile component in early time,dominating tensile deformation in middle and later periods when polymetallic sulfide quartz vein formed,and compressive shear of fractures filled with quartz,carbonate and polymetallic sulfide in later. Furthermore,this study summed up the distribution regularities of the ore bodies in the fault belt. The result of deep geochemistry shows that ore types and ore mineral assemblage are characterized by zone subdivision in vertical direction. Reverse zone subdivision of mineral assemblages is consistent with deep mineralization superposition indicated by geochemical primary halos. It is inferred that the potential ore bodies exist below -506m in the deposit based on the distribution law of ore bodies in the faults and the primary halo characteristics. This study provides a line of important evidence for exploration of deep-seated ores.