滇东南底圩金矿地质特征及找矿预测

底圩金矿是滇东南地区目前发现的少有的中大型金矿,矿石元素组合为砷金型,成因上属浅成(中)低温热液(超)微细浸染型金矿。从矿床地质特征出发,结合邻区资料探讨了矿床的控制因素:(1)底圩金矿与沿向北突出的文山富宁弧形逆冲推覆构造带圈层状产出的多个金矿带应是统一的有机体,逆冲推覆构造是控制矿床成带产出的主要因素,较为完整的短轴破背斜是矿床定位的极好场所,破背斜轴部不同方向断裂交汇区、背斜转折端、倾伏端以及古喀斯特溶洞发育之处是极好的容矿空间;(2)节理、裂隙、孔隙发育的峨眉山玄武岩是最主要的赋矿岩石,主成矿期应为燕山晚期;(3)低温相对封闭、稳定的环境是形成(中)低温元素组合微细浸染金矿所必须的物理环境。矿区深边部及外围找矿预测应紧紧围绕底圩破背斜轴部不同方向断裂交汇区、背斜转折端、倾伏端以及古喀斯特溶洞发育地段开展工作,除考虑玄武岩赋金外,还应考虑P2β与P1m的下伏不整合面和上覆三叠系地层。并探讨了矿区深边部及外围找矿预测应注意的地质物化探标志问题。

Geological Features and Ore Prediction of Dixu Gold Deposit in Southeast Yunnan Province, China

Dixu gold deposit is one of the unusual medium-large-scaled gold deposits discovered in Southeast Yunnan Province,in which As and Au are closely associated.Genetically,the deposit belongs to epithermal(mesothermal) super fine-grained contaminated gold deposit.Based on the geological features,the genesis and the controlling factors of the deposit are discussed:(1)Dixu gold deposit is one of the gold deposits occurring as belts along Wenshan-Funing thrust nappe structure,which is the key controlling factor for gold deposits while short-axial anticline is one of the best locations for gold mineralization and short-axial anticlines are the favorite location for ore bodies;(2)Ermeishan basalt with joints,cracks,and pores are the most important ore-hosting rocks;(3)Rather trapped environment with low temperature is the necessary physical environment for the formation of epithermal(mesothermal) fine-grained disseminated gold deposits.The direction of exploration has been discussed and forecast in outer and deeper areas of this deposit.