云南普朗斑岩铜矿晚三叠世构造控矿条件

LATE TRIASSIC ORE-CONTROLLING STRUCTURES OF PULANG PORPHYRY COPPER DEPOSIT IN YUNNAN PROVINCE

普朗铜矿是义敦岛弧东多金属矿带的超大型斑岩型铜矿床.成矿带内岩浆构造活动频繁,裂隙构造叠加成矿-控矿作用显著,但研究程度薄弱.在对普朗铜矿区巷道进行构造岩相学综合调查研究的基础上,结合区域成矿构造背景,厘定矿区褶皱、断裂宏观特征,对典型中段进行节理(裂隙)测量分析.研究表明:1)古特提斯洋闭合过程斑岩铜矿成矿作用与晚三叠世构造演化、岩浆活动关系密切,普朗铜矿形成于俯冲造山阶段;2)区域深大断裂控制着矿区沉积建造和岩浆岩分布,矿床总体产于普朗背形核部,次级NEE及NE向断裂控制着含矿斑岩体和节理(裂隙)的发育,矿(化)体赋存于两组断裂交汇部位;3)矿区以张节理为主的复合型节理系统,为含矿热液的运移、扩散和富集提供导矿、储矿空间,裂隙发育程度与铜矿化呈正相关.通过对矿区岩浆侵入-构造裂隙系统特征与控矿规律的研究,认为热液脉状矿(化)体严格受控于构造-裂隙系统改造富集作用,裂隙构造发育部位是探寻富“脉状矿”的有利靶区.

Pulang copper deposit is of a super-large porphyry type in the eastern Yidun island arc polymetallic ore belt with frequent tectonic magmatic activities and significant superposition of fissure structure and ore forming-ore controlling conditions.However,the research degree is weak.Based on the comprehensive study of tectonic petrography of tunnels in Pulang copper orefield,combined with the regional metallogenic tectonic setting,the paper determines the macroscopic characteristics of folds and faults,and analyzes the joints/fissures in the typical levels.The results show that the mineralization of porphyry copper deposit during the closure of Paleo-Tethys Ocean is closely related to the Late Triassic tectonic evolution and magmatic activity,with Pulang copper deposit formed in subduction orogeny stage.The regional deep faults control the sedimentary formation and magmatite distribution in the orefield.The depositis is generally occurred in the core of Pulang antiform.The secondary NEE-and NE-trending faults control the development of ore-bearing porphyry and joints/fissures,while the ore/mineralized bodies occur at the junction of two groups of faults.The tension joint-dominated compound joint system provides passage and storage space for ore-bearing hydrothermal fluid migration,diffusion and enrichment.The development degree of fissures is positively correlated with copper mineralization.By studying the characteristics of magmatic intrusion-tectonic fissure system and ore-controlling rule in the orefield,it is considered that the hydrothermal vein ore/mineralized bodies are strictly controlled by the reformation and enrichment of tectonic and fissure system,and the site where fissure structure is well-developed is favorable target for vein ore prospecting.