【作者】 王祖伟；

【导师】 涂光炽； 周永章；

【作者基本信息】 中国科学院研究生院（广州地球化学研究所） ， 地球化学， 1998， 博士

【摘要】 粤西庞西垌—桂东南金山银金成矿带地处广东廉江市和广西博白县的交界，大地构造位置属华南云开加里东变质地体的西南端，西侧是云开地块西部围限大断裂岑溪—博白断裂带。云开地块基底主体是加里东构造层，是一套原岩以泥沙质为主夹火山岩的沉积变质建造，整体上具有Au、Ag富集的地球化学背景。 庞西垌—金山矿带内有庞西垌、金山、中苏、大沙等规模不等的银矿床(点)产出。带内广泛分布的前寒武系-寒武系变质地层建造，具有富Ag、高Ag/Au比值的特点，与云开地块东部高Au/Ag比成反差，这是该区形成以银为特色的贵金属矿床成矿带的重要因素之一。 银金矿床赋存在呈NE向展布的庞西垌—金山断裂带内，以银为主，伴生Au、Pb和Zn等矿化，是典型蚀变构造岩型矿床。矿床在中生代形成，经历了硅化—石英阶段、黄铁矿—石英阶段、多金属硫化物阶段、石英—碳酸盐阶段等演化阶段。其中，贵金属矿化与硅化和黄铁矿-多金属硫化物化关系最为密切。矿体主要是硅化、多金属硫化物化的蚀变岩和部分石英脉。 庞西垌—金山银金矿床是一构造变形—热液蚀变—矿化扭结体系。通过提取数学不变量，并以此为基础进行质量平衡定量估计表明，热液围岩蚀变作用导致围岩的质量总体增加。在热液围岩蚀变过程中，贵金属元素(Ag、Au)和矿化指示元素(As、Bi、Sb、Cu、Pb、Zn、Se、Te)等属于不断被带入元素，而亲铁元素(Ni、Co)和多数亲石元素(Nb、Ta、Zr、Hf等)基本保持不变或有弱的亏损或富集。 庞西垌—金山银金矿床是多期多阶段地质地球化学演化的产物。在前寒武纪-寒武纪矿源层形成期间，成矿元素发生了初步的富集。前寒武纪-寒武纪沉积变质建造是成矿物质的主要来源；在加里东区域变质作用过程中，矿源层中的元素经历了活化、迁移，伴随重新分配；在中生代期间，断裂构造、岩浆活动伴随岩石变形和热液蚀变作用，使矿床得以最终定位。 花岗岩不是成矿物质的主要来源，但晚燕山期英桥同熔型花岗岩浆活动对成矿作用扮演了非常重要的作用。它为以大气降水为主混有岩浆热液的成矿流体的形成和循环提供了驱动力——热能。 应用区域丰度法和分形—储量模型，对研究区及所在市县的资源远景进行了估计，结果表明Ag具有良好的资源前景。更多还原

【Abstract】 The Pangxidong-Jinshan Ag-Au mineralization belt is located along the boundary zone of Guangdong and Guangxi,southern Chnia,It is part of the famous Yunkai metamorphic block in term of tectonics. The latter has a Au-Ag-rich basement,and the studied Lianjiang - Bobai region is specially high in the ratio of Ag/Au in contrast with other areas of the Yunkai block.The Ag-Au deposits are distributed along the Pangxidong-Jinshan fault system,and compsed mainly of hydrothermally altered deformed-rocks and quartz veins. There are four mineralization phases,including the silicification - quartz phase (I),the quartz - pyrite phase (II),the multiple metallic sulfide phase (III) and the quartz-calcite phase (IV). Si and Ag,Au and the like are included among the introduced elements during hydrothermal wall-rock alteration .The deposits resulted from multiple phases of geological and geochemical evolution. A source formation rich in noble metals was formed during the Precambrian-Cambrian period,and the mineralization elements were redistributed with the source rocks during the Jinning and Caledonia regional metamorphic period. Magmatism and deformatiom were developed during the Yanshan stage,followed by hydrothermal alteration,of which final mineralization is an integral part.The regional abundance method and the fractal model are used to estimate the resource potentiality of noble metals in the studied region,and the result indicates that the region has a sound prospect in reserve of Ag and Au.更多还原