对小秦岭小河岩体南缘董家埝银矿地质特征及成因的初步认识

Dongjianian Silver Deposit in the Southern Margin ofXiaohe Rock Mass,Xiaoqinling Mountains

董家埝银矿是近年来在豫西小秦岭地区小河岩体南缘发现的一个银矿床。矿(化)体产出于太古代太华群或中元古代管道口群与中元古代小河花岗岩体接触带,矿体呈陡倾斜较规则脉状产出,具分枝复合现象。综合其地质背景、矿床地质特征以及区域典型矿床类比研究表明:其矿床类型为热液脉状银矿床,对比相似矿床推测其矿床成因与中生代岩浆活动密切相关,成矿年代为晚中生代。矿石中Ag、Pb、Zn多金属共生,Ag/Au比值很高,不出现Au的富集,Pb/Zn比值>1,是一个以银为主,伴生铅、锌的矿点。构造破碎带、铅锌矿化、烟灰色硅化、绢云母化等矿化蚀变、民采坑以及银铅锌元素异常组合是其重要的找矿标志。为矿区及其小河岩体南缘进一步找矿提供了指导方向。

Dongjianian silver deposit is a silver deposit discovered in recent years in the southern margin of Xiaohe rock mass in Xiaoqinling area,western Henan Province.Ore bodies occur in the contact zone between Archaean Taihua Group or Mesoproterozoic Pipeline Mouth Group and Mesoproterozoic Xiaohe granite body.Ore bodies are steeply inclined and regularly veined with branching and composite phenomena.Based on the geological background,geological characteristics of the deposit and the analogy of typical regional deposits,it is concluded that the deposit type is hydrothermal vein silver deposit,and the genesis of the deposit is closely related to Mesozoic magmatic activity,and the metallogenic age is Late Mesozoic.The Ag,Pb and Zn polymetals coexist in the ore.The Ag/Au ratio is very high,and there is no Au enrichment.The Pb/Zn ratio is more than 1.It is a silver-dominated ore spot with lead and zinc.Mineralization alteration such as tectonic fracture zone,lead-zinc mineralization,smoke-gray silicification,sericite mineralization,mining pits and anomalous combination of silver,lead and zinc elements are important prospecting indicators.This paper provides guidance for further prospecting in the mining area and the southern margin of Xiaohe rock mass.