黑龙江金厂铜金矿床地质特征及成因探讨

Geological Features and Genesis of the Jinchang Cu-Au Deposits in Heilongjiang Province

金厂铜金矿床是中国东北的一个特大型矿床,大地构造位置处于兴蒙造山带东缘,成矿时代集中于110～130Ma。金厂铜金矿床矿体类型主要为角砾岩型和裂控型。角砾岩型矿(化)体以J-1矿体为代表,产于穷棒子沟Ⅰ号角砾岩筒内,为典型的隐爆角砾岩筒,全筒矿化,与围岩界限清楚。矿区内角砾岩型矿体常成群成串出现,东西走向具等间距分布特征。裂控型矿体包括环形和放射状矿体,环形矿体以Ⅱ和18号脉群为代表,放射状矿体以Ⅲ脉群为代表。Ⅱ脉群处于裂控型矿体的上部,18号脉群处于Ⅱ脉群的下部,矿体呈层状或脉状分布,在剖面上具"背形"分布特征,环形矿体由内向外存在矿化分带现象。金厂铜金矿床产于太平洋板块俯冲产生的陆缘弧环境,其流体性质及成矿物质来源均与深部岩浆岩有关,角砾岩型矿体和裂控型矿体均具有斑岩型矿床的成矿特征。

The Jinchang Cu-Au deposit, geographically located in Northeast China and tectonically in the easternmost part of the Xingmeng orogenetic belt, is a super-large gold deposit with a mineralization age between 110 - 130Ma. Its gold ore types are mainly breccia and vein types. The typical brec- cia-type ore body No. J-1 occurs in the breccia pipe No. I in Qiongbangzigou, which displays as a cryptoexplosion breccia pipe with entire pipe minerali-zation and clear boundaries with wall rocks. The breccia-type ore bodies often appear in clusters and groups, and are equally spaced in an east-west trend. The vein-type ore bodies include ring-like and radiated ore bodies; the vein groups of II and I8 are typical ring-like orebodies; and the vein group II1 is of a typical radiation pattern. As a whole ring-like ore bodies are distributed as a layered or vein type on the surface and an arc shape on profile, the vein group II is located in the upper part of the magma dome, and the vein group I8 in the lower part. These ring-like orebodies exhibit mineralization zoning outward. The Jinchang goht deposit is situated in the margin of the continental arc setting produced by Pacific plate subduction, and its fluids and ore- forming materials result from the deep source magma. All breccia type and magma-dome type ore bodies show mineralization characteristics of porphyry de- posits.