柴北缘地区的两类块状硫化物矿床——Ⅰ.锡铁山式SEDEX型铅锌矿床  

Two types of massive sulfide deposits on northern margin of Qaidam basin, Qinghai Province: Ⅰ. Xitieshan style SEDEX lead-zinc deposits

作　　者：张德全[1] 王富春[2] 李大新[1] 丰成友[1] 佘宏全[1] 李进文[1] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]青海省地质调查院,青海西宁810012

出　　处：《矿床地质》2005年第5期471-480,共10页Mineral Deposits

基　　金：国家科技攻关计划(2003BA612A_07);国家自然科学基金(40372051)的资助

摘　　要：作者以连续的两篇文章综述了柴北缘地区的加里东造山带中产出的两类不同的块状硫化物矿床,这就是喷流沉积(SEDEX)型Pb_Zn矿床和火山岩容矿的块状硫化物(VHMS)型Cu_S矿床。认为它们在成矿后的造山过程中受到过不同程度和不同成矿作用的改造,使之兼有后生矿床的特征。锡铁山Pb_Zn矿床的主体是属于以沉积岩为容矿岩石的喷流沉积(SEDEX)型矿床。它的含矿岩系形成于早奥陶世〔(486±13)Ma〕弧后盆地环境中,并在加里东期碰撞造山过程中发生了强烈的北东—南西向斜向挤压缩短,导致喷流沉积成矿作用形成的原始铅_锌_黄铁矿层,后期遭受了强烈的构造改造,从而在一定程度上使矿体的空间分布受到后期构造的控制。此外,该矿床也程度不大地受到过后期热液改造。为更加显示它的地区性特色和强烈的后期改造,作者建议将其称为“锡铁山式SEDEX型铅锌矿床”。在该式矿床的勘查过程中,既要注重研究同生成矿作用对矿体的控制,也要重视研究后期构造对含矿层和矿体的破坏和改造。Two types of massive sulfide deposits occur in the Caledonian orogenic belt along the northern margin ot Qaidam basin, i. e. sedimentary exhalative （SEDEX） Pb-Zn deposits such as the Xitieshan Pb-Zn deposit and volcanics-hosted sulfide （VHMS） Cu-S deposits like the Qinglongtan Cu-S deposit. They were reformed in different degrees by different ore-forming processes during the orogenic activity after the formation of massive sulfide orebodies, thus having both syngenetic and epigenetic characteristics. The main orebodies of the Xitieshan lead-zinc deposit occur in sedimentary rocks and belong to Sedex type. Their host rocks （with zircon U-Pb age of 486 ± 13 Ma） were formed in Early Ordovician backarc basin and underwent intense NE-SW trending compression-shortening deformation during the Late Caledonian collision, resulting in structural reformation and structural control of the original lead-zinc-pyrite horizon. In addition, the Xitieshan lead-zinc deposit was more or less reconstructed by epigenetic hydrothermal fluids. It is suggested that the deposit be termed Xitieshan-style leadzinc deposit so as to emphasize its local characteristics and distinguish it from classical SEDEX-type deposits. Importance should be attached to both the controlling role of syngenetic structures and the destruction and/or refor mation of epigenetic structures in the prospecting for orebodies of this type of deposits.

关 键 词：地质学 SEDEX型Pb-Zn矿床 锡铁山式Pb-Zn矿床 柴北缘 

分 类 号：P618.42[天文地球—矿床学] P618.43[天文地球—地质学]