滇西北衙金多金属矿床成矿构造特征及地质勘查意义

通过对北衙矿区构造地质特征和侵入体构造特征的野外详细调查,并结合前人的科研成果,系统总结了北衙金多金属矿床成矿构造和成矿结构面的特征,构建了矿区成矿构造的空间格架,建立了成岩成矿构造有序、配套的矿床成矿构造系统。研究认为燕山期?喜马拉雅早期形成的SN向北衙向斜和断裂、EW向隐伏断裂、层间破碎带、富碱斑岩侵位形成的接触带构造是矿区主要的成矿构造。以SN向断裂构造为主体,相配套的EW、NE、NW向断裂构造,深部与马鞍山断裂带及金沙江?红河深大断裂连接,构成了矿区构造?岩浆活动?成矿的网络构造系统,控制了斑岩?矽卡岩?热液脉型矿床成矿系统的发育和空间分布。山间盆地构造和不整合面构造是表生作用形成的风化?堆积型铁金矿床的重要成矿构造。山间盆地构造及其中发育的上新统三营组和成矿后的SN向逆掩?推覆构造,对斑岩?矽卡岩型矿床和风化?堆积型矿床的变化与保存具有重要的控制作用。矿区构造演化经历了燕山期?喜马拉雅早期EW向主压应力作用→喜马拉雅中期主压应力从EW向转为SN向→喜马拉雅晚期主压应力方向转变为近EW向的三期构造作用过程。成矿构造研究成果对提高控岩控矿规律认识和指导勘查工作部署具有重要的理论和实际意义。

Characteristics of Metallogenic Structures in the Beiya Gold-poly-metallic Deposit in Northwestern Yunnan Province and Geological and Exploration Applications

Based on detailed field investigation of the tectonic geological characteristics and intrusive structural characteristics of the Beiya deposit,combining previous research results,this paper summarized the features of the metallogenic structures and structural surfaces in the Beiya Au-polymetallic deposit,constructed a space lattice frame of the ore-forming structures,and established a ore-forming structure system matching the magma,mineralization and structure.It is considered that the SN-trending Beiya syncline and fault,the EW-trending buried fault,the interlayer fracture zone and the contact structure of the alkaline porphyry formed in the Yanshanian-early Hemalayan periods are the main metallogenic structures of the deposit.The SN-trending faults,and the subordinated EW,NE and NW-trending faults,are connected with the Maanshan fault zone and the Jinshajiang-Honghe deep fault.These faults constitute a network structure system of tectonic-magmatic activity and mineralization,and control the development and spatial distribution of the porphyry-skarn-epithermal metallogenic system.The intermountain basin tectonics and unconformities are important ore-forming structures of the supergene weathering-accumulating iron-gold orebodies.The intermountain basin tectonics and the Pliocene Sanying Formation(N2s)deposited in the basin,together with the post-mineralization SN-trending reverse cover tectonics control the change and preservation of porphyry-skarn orebodies and weathering-accumulating orebodies.The area experienced three stages of tectonic evolution,i.e.,the EW-trending principal compressive stress in the Yanshanian-early Hemalayan periods,the EW to SN-trending principal compressive stress in the Middle Himalayan period,and the near EW-trending principal compressive stress in the Late Himalayan period.The results of metallogenic structure research are of great theoretical and practical significance for improving the understanding of the ore control mechanisms and guiding the layout of exploration.