河南罗山金城金矿床成矿条件与深部找矿前景分析

Metallogenic Conditions and Ore-Searching Prospect at Depth of the Jincheng Gold Ore Deposit in Luoshan County,Henan Province

河南省罗山县金城金矿床位于桐柏-大别造山带中部大别山西北侧,北邻桐柏-商城韧性剪切带,西邻燕山晚期灵山花岗岩体。矿体受近东西向的断裂构造控制,呈脉状、透镜状产于中元古界浒湾(岩)组变质岩中,为一受韧脆性剪切带控制的中低温热液金矿床。赋矿岩石为蚀变斜长角闪岩、蚀变二云母片岩以及薄层大理岩互层带。金城金矿矿石构造以浸染状、细脉状和角砾状为主,主要载金矿物为黄铁矿,早世代的自然金以裂隙金的形式赋存于第一世代自形粗粒黄铁矿裂隙中,晚世代的自然金以包裹体金的形式赋存于第二世代稠密他形细粒黄铁矿颗粒中。结合地质、构造叠加晕、CSAMT资料,笔者认为Ⅰ号矿体和Ⅳ号矿体在0线东北部向深部有延伸趋势,该地段标高-300m以下具有较好的找矿前景。

The Jincheng gold deposit in Luoshan county, Henan Province is located in the middle of the Tongbai - Dabie orogenic belt, northwest of the Dabie Shan. It abuts the Tongbai - Shangcheng ductile zone in the north, and the late Yanshian Lingsban granitic bodies in the west. This deposit is con-trolled by nearly EW - trending faults, and occurs in the Huwan Fm. metamorphic rocks as veins or lenses, belonging to a low to intermediate temperature hydrothermal gold deposit. The host rocks include altered amphibolite, altered schist and thin marble. The ores are dominated by disseminated, veinlet, and brecciated textures. Pyrite is the main gold - hearing mineral, and the native gold in the early stage occurs in the boundary of pyrite grains, and the n- ative gold in the later stage as inclusions in pyrites. Geological features, geophysical and geochemical data suggest that ore bodies No. Ⅰ and o Ⅳ northeast of the line No. 0 extend downward,indicative of a good prospect of ore - search below the depth of 300m in this section.