从赋矿岩系岩石类型的多样性论羊拉铜矿的成因  

A Discussion on Origin of Yangla Copper Deposit in Light of Diversity of Ore-hosting Rock Types

作　　者：曲晓明[1] 杨岳清[1] 李佑国[2] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]成都理工大学,四川成都610059

出　　处：《矿床地质》2004年第4期431-442,共12页Mineral Deposits

基　　金：国家"十五"科技攻关项目(课题号:2001BA609A-5)的阶段性成果

摘　　要：通过野外调查和室内工作,将羊拉铜矿床按矿石的矿物成分和组构分出9种类型,包括矽卡岩型、大理岩型、砂板岩型、角岩型、凝灰质流纹岩型、玄武岩_辉绿岩型、花岗质碎裂岩_花岗斑岩型、安山岩型和绢英岩型。矽卡岩型矿石是构成矿体的最主要矿石类型,但在不同矿段可由碳酸盐岩(里农)和凝灰质火山岩(贝吾)两种原岩形成。矿体在赋矿岩系中有3种产出形态顺层呈层状_似层状;沿花岗岩与沉积岩接触面呈透镜状;贯穿岩体和沉积岩呈大脉状。它们均与后期构造密切相关,矿体无确定的顶、底板岩石,围岩蚀变以矿体为中心呈环带状分布。研究表明,矿床相对赋矿岩系显示出明显的后成性,属于印支期花岗岩_花岗斑岩与古生代混杂岩通过强烈的接触交代作用形成的矽卡岩型铜矿床。The Yangla copper deposit is located in Jinshajiang suture belt on the eastern margin of Tibetan plateau. In Triassic, subduction and closure of the Jinshajiang oceanic basin and the associated continent_continent collision led to the formation of ophiolitic mélange composed of blocks of different ages and various lithologic characters to the west of Zhongza terrane. The Indosinian large_scale magmatic intrusion caused mobilization and concentration of ore_forming materials contained in the mélanges. Based on field geological investigations and geochemical ore studies, the authors found that almost all of the rock types occurring in the ore district were involved in the copper mineralization. According to mineral compositions and ore fabrics, 9 ore types have been recognized, namely, skarn, carbonate, slate_hornfels, tuffaceous rhyolite, basalt, gabbro_diabase, granite porphyry, breccia, and phyllic type. The skarn ore is the most important type and was formed from two kinds of original rocks of carbonate and tuffaceous volcanite respectively in the Linong and the Beiwu mine segment. The orebodies generally assume 3 modes of occurrence: stratified_stratoid forms along the bedding of wall rocks, lenses in the contact zones of granite with sedimentary rocks, and large veins penetrating granite and sedimentary rocks. The orebodies have no definite top and bottom rocks. Wall alteration shows zonation around the central ore. The mineralization shows obvious epigenetic characteristics and genetically belongs to skarn_type copper deposit formed from strong contact metamorphism of Indosinian granites with Paleozoic mélange of Gajinxueshan Group.

关 键 词：地质学 金沙江缝合带 赋矿岩系 矽卡岩 铜矿床 羊拉 云南 

分 类 号：P618.41[天文地球—矿床学]