中文摘要：

摘要夕卡岩是滇东南老君山成矿区众多锡多金属矿床的主要赋矿围岩。本文在系统分析了夕卡岩的产状特征和矿物组成特征的基础上，采用岩石化学和微观结构、构造相结合的方法，进行了原岩恢复。认为该类夕卡岩的原岩中含有大量中．基性火山岩，其形成过程与海相火山活动有关。滇东南地区寒武纪为大陆边缘拗陷盆地构造环境，含矿夕卡岩微量元素组成特征与火山弧玄武岩类似，推测研究区在早加里东期区域拉张作用背景下，盆地地壳变薄导致地幔物质上涌，岩浆在上升过程中与地壳物质发生了混杂作用，最终在拗陷盆地中心形成海相中-基性火山喷发及成矿作用。研究区中、下寒武统均有火山喷流沉积岩分布，反映了该区海相火山活动的多期次性。该套含矿夕卡岩为火山喷流沉积岩与其它正常海相沉积物混杂后，经印支期区域变质作用形成。

英文摘要：

Skarn is one of the main ore bearing rocks in Laojunshan tin poly-metallic metallogenic region. This paper analysized occurrences and mineral compositions of the skarns systematically, combine with the study of microtexture, structure and petrochemistry, original rocks of the bearing skarns was discussed. Research has revealed that the original rocks of the skarns were intermediate-basic volcanic rocks, the rocks＇ forming processes were related to marine volcanic activities. Southeast Yunnan province was a continental margin depressed basin during Cambrian period, the trace elements characteristics of ore bearing skarns were the same as volcanic-exhalative-sedimentary-origin orcks. During the early Caledonian period as a regional tension background, the basin crust became thinner and mantle material upwelling, the magma melting and mixed with the crust, and intermediate-basic volcanic eruption in the central of the depressed basin. The submarine volcano-sedimentary rocks could be found in Lower and Middle Cambrian in the study area, this reflect there are many stages of volcanic eruptions in the area. The ore bearing skarns were formed by volcano-sedimentary rocks mixed with normal marine sedimentary rocks, and impacted by the regional metamorphism of Indo- Chinese epoch.