滇东南麻栗坡一带中生代构造变形及其对钨多金属矿床的控制作用  

Mesozoic tectonic deformation and ore-controlling of tungsten polymetallic deposits in Malipo area,southeastern Yunnan

作　　者：毕珉烽[1] 张达[1] 吴淦国[1] 狄永军[1] 阙朝阳[1,2] 潘锦波 薛伟[1] 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]紫金矿业集团西北有限公司,新疆乌鲁木齐830026

出　　处：《地学前缘》2015年第4期223-238,共16页Earth Science Frontiers

基　　金：云南省麻栗坡县政府委托项目"云南省麻栗坡县老君山地区钨多金属矿床成因及成矿预测"

摘　　要：滇东南麻栗坡一带位于Song Chay穹窿的北部,华南板块的西南部,经历了多期强烈的构造活动。该区主要地质体野外构造变形解析表明,麻栗坡一带深部深变质岩到浅部浅变质沉积地层均受到SE-NW向挤压构造变形作用,并在不同地质体之间发育多条自SE向NW运动的低角度逆冲推覆构造。在穹窿内部,逆冲推覆构造形成了两套变质沉积岩地层(洒西岩组和南秧田岩组)以断片的形式夹在火成岩(团田+老城坡片麻状花岗岩和南捞构造片麻岩)之间的空间叠置关系。在穹窿外围,外来岩系(寒武系—泥盆系地层)逆冲推覆到原地岩系(二叠系—三叠系地层)之上。这期逆冲推覆运动沿构造带形成了飞来峰、断夹块、糜棱岩带、斜歪褶皱、矿物剪切变形等构造现象,强烈改造了该区早期构造格局。结合与推覆构造变形密切相关的主要地质体锆石U-Pb同位素年代学以及前人研究成果,认为上述推覆构造运动发生在中—晚三叠世到159 Ma,区域上与中生代古太平洋板块向NW挤压华南板块的构造事件一致。中生代构造变形在研究区不仅控制了区域钨多金属矿床赋矿层位的展布,同时也为晚期钨多金属矿化富集提供了储矿空间。Malipo in the southeast part of Yunnan Province, located in the north of the Song Chay dome and in the southwest of the Southern China plate, has undergone periods of intense tectonic activities. There is a thrust nappe structure in the SE-NW direction shown by tectonic deformation analysis from metamorphic rock to sedimentary layers. Inside the Song Chay dome, the extrusion caused the formation of two metamorphic sedimentary strata （Saxipetrofabric and Nanyangtian petrofabric）which presented as fault blocks in between the igneous rocks （Tuantianq-Laoehengpo gneissic granite and Nanlao tectonic gneiss）. In the outer area of Song Chay dome, the allochthonous sequences （Cambrian strata and Devonian strata） were thrusted onto the autochthonous sequences （Permian strata and Triassic strata）. The thrust nappe structure deformation is characterized by klippen, fault block, mylonite zone, inclined fold and mineral shear deformation~ It has changed the regional tectonic framework. According to both the age of Zircon U-Pb and previous research results, this extrusion began in the Middle-Late Triassic, and ended in 159 Ma. This extrusion was consistent with the large-scale compression of the NW Pacific and South China plates during the Mesozoic period. This Mesozoic tectonic event provided the space for the following tungsten polymetallic mineralization.

关 键 词：麻栗坡 SONG Chay穹窿 逆冲推覆构造 构造解析 锆石U-PB年龄 

分 类 号：P618.67[天文地球—矿床学]