滇西南翁孔坝铜多金属矿床构造控矿模式

Tectonic Ore Control Model of Wengkongba Copper Polymetallic Deposit in Southwest Yunnan

滇西南翁孔坝矿床位于南澜沧江火山弧成矿带北段,是该成矿带内与中晚三叠世火山岩密切相关的铜多金属矿床的典型代表之一.前人研究显示,构造是控制该类型铜多金属矿床形成和分布的重要因素,但其构造控矿方面的研究却十分薄弱.本文运用矿田地质力学理论与方法,通过该矿床不同类型构造的精细解析,阐明该矿床的成矿构造体系与构造控矿规律.结果表明,该矿床自印支期以来主要经历了四期构造活动,主压应力方向也经历了近SN向→近EW向→NE向→NW向的转化,依次形成东西构造带、南北构造带、北西构造带和北东构造带.其中,东西构造带控制了印支中晚期火山沉积成岩作用和矿化初始富集,南北构造带对火山沉积岩系进行了构造改造,控制着工业矿体的形成和分布.研究成果对深化区域铜多金属矿床构造控矿模式具有借鉴意义,而且对其深部找矿具有指导作用.

The Wengkongba deposit in Southwest Yunnan is located in the northern section of the Nan-Lancangjiang volcanic arc metallogenic belt and is a typical representative of copper polymetallic deposits closely related to volcanic rocks of the Middle and Late Triassic within this metallogenic belt.Previous studies have shown that tectonics play a crucial role in controlling the formation and distribution of this type of copper polymetallic deposit,but research on the tectonic control of ore deposits has been limited.In this study,using theories and methods of field geological mechanics,we conducted a detailed analysis of the different types of structures in the deposit to elucidate the ore-forming structural system and tectonic control patterns of the deposit.The results indicate that the deposit has experienced four stages of tectonic activity since the Indosinian period,and the main stress direction has shifted successively from near-SN to near-EW to NE to NW.These stages formed the East-West structural zone,North-South structural zone,Northwest structural zone,and Northeast structural zone,respectively.Among these,the East-West structural zone controlled the volcanic-sedimentary diagenesis and initial mineralization during the Middle-Late Indosinian period,while the North-South structural zone led to structural modifications in the volcanic-sedimentary rock series and controlled the formation and distribution of industrial ore bodies.The findings of this study have significant implications for deepening the exploration in the area.