湖南黄沙坪铅锌矿NNW向构造的识别及其找矿意义

Identification of the NNW Trending Ore-Controlling Structure in the Huangshaping Lead-Zinc Deposit,Hunan Province and Its Significance to Exploration

湖南黄沙坪铅锌矿床属岩浆期后热液型矿床,近年来由于危机矿山深部找矿项目取得重大找矿进展而引起各方关注。矿床经历了多期构造活动,包括NNE向、近NE向和NNW向,但以往一直将NNE向作为控岩控矿构造。系统的地质调查及岩体对比发现,NNE向断裂为成矿前逆冲构造,控制区内的褶皱与石英斑岩的侵入,并在成矿期继续活动。NNW向构造控制了矿区内花岗斑岩(301#、304#)的侵入以及矽卡岩及其相关的钨钼矿、铅锌矿的成矿。铅锌矿体受NNW与NNE向断裂的联合控制,常呈"S"型、或两组断裂交汇处的不规则脉状。矿化以NNW向花岗斑岩为中心形成分带,矽卡岩型钨钼矿化分布于花岗斑岩体边部,铅锌矿体分布于外侧。NNW向控矿构造的认识揭示出黄沙坪矿床301#花岗斑岩体及其东南部深部地区将是重要的找矿方向;同时,301#-304#岩体构成的NW构造线两侧,具有进一步寻找小型铅锌矿体的条件,这些矿体主要位于NNE与NNW向断裂的交汇部位。

The Huangshaping Pb-Zn deposit lies in the central part of the Nanling non-ferrous metallogenic zone, Hunan province. In recent years,it has been much concerned for important advances of the project to search minerals at depth in this area. Geological data suggests that this area has experi- enced many periods of tectonic activity associated with NNE and EW trending faults. Previously the NNE faults are considered to be the ore-controlling structure. But new geological investigation and rock comparison suggest that the NNE faults were the thrusts prior to mineralization ,which controlled folds and intrusion of quartz porphyry, and continued to be active during ore-formation time. While the NNW trending structure controlled the intrusion of granite phorphyry, skarn rock and related ore formation of W-Mo and Pb-Zn. Both NNW and NNE trending faults have major controlling effect on the ore bodies which look like S or irregular vein shapes at the intersection of the two sets of faults. Mineralization can be divided into zones around the center of granite porphyry,where the skarn-type W-Mo ore bodies occurred at the rim of the porphyry, and Pb-Zn at outside flank. This new perspective that the NNW trending controlling structure suggests that the porphyry No. 301 and its southeast will be an importation district for further exploration, and both sides of the NW line made up of rock boodles No. 301 and No. 304 have conditions for small Pb-Zn deposit exploration, since they are located at intersection between the NNE and NNW faults.