区域构造体制对湘东南印支期与燕山早期花岗岩成矿能力的重要意义——以千里山岩体和王仙岭岩体为例  

Important significance of regional tectonic regime to metallogenic capacity of Indosinian and Early Yanshanian granites in southeastern Hunan:A case study of Qianlishan and Wangxianling plutons

作　　者：柏道远[1] 贾宝华[2] 李金冬[2] 王先辉 马铁球 张晓阳 陈必河 

机构地区：[1]中国地质大学,湖北武汉430074 [2]湖南省地质矿产勘查开发局,湖南长沙410011 [3]湖南省地质调查院,湖南湘潭411100

出　　处：《矿床地质》2007年第5期487-500,共14页Mineral Deposits

基　　金：中国地质调查局区域地质调查项目(200213000035);湖南省"湘东南中生代构造演化与成矿"项目(2003-3)的联合资助

摘　　要：湘东南是华南重要的中生代有色金属矿集区。区内,印支期王仙岭岩体与燕山早期千里山岩体紧密相邻,前者成矿差,后者则发育多个大型、超大型矿床。两岩体的地层及构造地质条件相近,都具有W、Sn多金属成矿花岗岩的岩石地球化学特征。王仙岭岩体内蚀变作用明显比千里山岩体普遍且强烈,W、Sn含量总体上明显高于千里山岩体。千里山岩体边缘有较多岩脉发育,岩体与碳酸盐岩围岩接触带矽卡岩化强烈;而王仙岭岩体边缘岩脉缺乏,岩体与碳酸盐岩围岩接触带以大理岩化为主。基于以上地质、地球化学表现,以及地球化学图解和区域构造演化背景分析,确定千里山岩体与王仙岭岩体的成矿差异,主要是由于两者侵位时的构造体制(应力场特征)不同所致:千里山岩体形成于后造山环境下的伸展构造体制,岩浆或岩体中的成矿物质能随流体沿断裂裂隙向周围有效扩散并于局部聚集、沉定而成矿;王仙岭岩体则形成于后碰撞环境下的弱挤压构造体制,侵位时断裂裂隙构造不发育,流体与成矿物质被封闭在岩体内部,因此未发生有效的成矿作用。据此推断,构造体制差异可能是造成湘东南印支期与燕山早期花岗岩成矿能力悬殊的关键原因之一。文章最后简单阐述了上述认识对区域找矿工作的启示意义。Southeastern Hunan is a nonferrous metal mineralized concentration area in South China. All the chief deposits are related to Early Yanshanian granites, whereas only very few Indosinian granites have formed largesized ore deposits. The Indosinian Wangxianling pluton is close to the Early Yanshanian Qianlishan pluton, and the geochemical diagrams and regional tectonic evolutional settings suggest that Wangxianling granites were formed in a post-collisional tectonic setting while Qianlishan granites were formed in a post-orogenic tectonic setting. Wangxianling granites have poor mineralization, while Qianlishan granites have formed several large or superlarge deposits. These two plutons have similar stratigraphic and structural conditions, and show characteristics of W-Sn-polymetallic granites. Wangxianling granites evidently have more widespread and strong alteration and higher contents of W and Sn than Qianlishan granites. Lots of rock veins occur on the margin of Qianlishan pluton, and skarnization is very intensive at the contact zone between the rock body and the carbonate wall rock. By contrast, there are only very few rock veins on the margin of Wangxianling pluton, and marbleization is the dominant alteration at the contact zone between the rock body and the carbonate wall rock. Based on the above geological and geochemical characteristics, the authors consider that the metallogenic differences between Qianlishan and Wangxianling granites are mainly attributed to the differences in tectonic setting and tectonic regime. Qianlishan granites were formed in an extensional post-orogenic setting, and the ore-forming elements in the magma and rocks spread effectively with the liquids along faults and fractures, resulting in precipitation and mineralization. Wangxianling granites were formed in a weakly compressional post-collisional setting with poorlydeveloped faults and fractures, and the liquids and ore-forming elements were confined in the pluton with no effective mineralization. Therefore, the difference of t

关 键 词：地质学 印支期 燕山早期 花岗岩成矿能力 构造体制 王仙岭岩体 千里山岩体 湘东南 

分 类 号：P611[天文地球—矿床学]