坦桑尼亚盖塔地区Nyankanga金矿床地质特征及成矿模式

Geological characteristics and metallogenic model of the Nyankanga gold deposit in Geita aera,Tanzania

Nyankanga金矿床是坦桑尼亚盖塔绿岩带规模最大的金矿床,位于坦桑尼亚克拉通北部。金矿床赋存在太古代火山—沉积序列中,围岩主要为条带状铁建造单元,被大型闪长岩体侵入。断裂构造发育,一系列NE-SW走向、NW倾向的断裂带穿切条带状铁建造单元和闪长岩体,Nyankanga断裂带是主要的变形区域,金矿化沿着条带状铁建造单元和闪长岩体接触带分布,金矿体赋存在断裂带中的角砾岩带中,闪长岩和条带状铁建造单元均有金矿化,但条带状铁建造单元中金品位更高。本文通过对Nyankanga金矿床区域成矿地质背景、矿床地质特征和控矿因素进行研究,建立Nyankanga金矿床成矿模式,认为:多期次岩浆侵入活动为成矿作用提供了丰富的成矿流体、成矿物质和能量;NE向的Nyankanga构造带是本区主要控矿构造,为金矿体的形成提供了有利空间。该成果可对该地区寻找同类型矿床提供参考。

Nankanga is the largest gold deposit in the Geita Greenstone Belt of the northern Tanzanina craton.The deposit is hosted within an Archean volcano-sedimentary package dominated by Banded Iron Formation and intruded by a large diorite complex.Banded Iron Formation and diorite intrusive complex are cut by a series of NE-SW trending,NW dipping fault zones,and the Nyankanga fault zone is a major deformation zone developed mainly along the ironstone-diorite contacts that is mineralization over its entire length.The gold ore bodies are hosted within the brecciation zone with Nyankanga fault zone by both diorite and Banded Iron Formation with higher gold grades.The area geology background,metallogenic geological characteristics and control factors were studied,and the metallogenic was established in this paper.The results shows that multi-phase magmatic activities provide a large number of ore-forming fluid,material and energy;The NE Nyankanga fault zone is the main ore-bearing structure in this area,and provides the favorable place for the gold ore bodies.