坦桑尼亚西嘎山一带铁建造型金矿床航磁异常特征及找矿意义

Areomagnetic anomaly of the iron formation type gold deposit in Siga hills area,Tanzania and its prospecting significance

坦桑尼亚条带状铁建造(BIF)型金矿床是该国绿岩带型金矿床中的一个主要类型,主要分布于坦桑尼亚维多利亚湖的西南部区域,姆瓦莫拉(Mwamola)金矿为苏库马兰德绿岩带(Sukumaland greenstone belt)上比较典型的大型隐伏铁建造型金矿床,位于坦桑尼亚西北部西嘎山一带;该类型矿床在航磁异常上表现为弱-中等强度线性磁异常,在地面磁异常上表现为中-强线性磁异常,条带状铁建造BIF(磁铁石英岩)和金矿石具有中强磁性,两者是引起磁异常的主要因素,磁异常是寻找该类型金矿的直接标志之一.根据姆瓦莫拉金矿床上的航磁异常表现特征,对西嘎山一带航磁异常形态进行了分析研究,认为航磁异常反映了与金矿有关的条带状铁建造的聚集分布区,金矿脉与航磁异常、地磁异常走向基本一致,据此选择的找矿靶区找矿效果良好,表明该区域航磁异常对选择靶区、寻找铁建造型金矿床具有一定的指导意义,坦桑尼亚西嘎山一带分布的航磁异常具有寻找铁建造型金矿的较大潜力.该区域金矿勘查,除充分利用该国已有的高分辨率航磁异常成果筛选靶区外,还需配合地面1∶1万高精度磁法测量确定条带状铁建造位置和进行钻探工程布置,借鉴或复制姆瓦莫拉和PL9110金矿找矿经验和模式,才能取得良好的找矿效果.

The Banded Iron Formation（BIF） type gold deposit is a main gold deposit type in the greenstone belt type gold deposits,Tanzania,it mainly distributed in southwest area of Lake Victoria.Gold deposit of Mwamola is a concealed large iron formation type gold deposit in the Sukumaland greenstone belt,It is located in the Siga hills area NW-Tanzania. This type of ore deposits shows weakmedium magnetic line anomaly in the aeromagnetic anomaly map,and shows medium-strong magnetic line anomaly in the geomagnetic anomaly map. The banded iron formation BIF（magnetite quartzite）and gold ore has medium strong magnetism,they are the main factor causing the magnetic anomaly,magnetic anomalies are indirect sign to find this type of gold deposit. According to characteristics of aeromagnetic anomaly on the Mwamola gold deposit,Anomalous morphology of the aeromagnetic anomalies in the Siga hills area are analyzed and studied, It is concluded that the aeromagnetic anomalies reflect the distribution of the banded iron formation for gold deposits,Gold veins and aeromagnetic anomalies,geomagnetic anomalies are basically same,according to the choice of prospecting target mining effect is good. It shows aeromagnetic anomalies to to find iron formation type gold deposit has certain guiding significance,aeromagnetic anomaly in Siga hills area has large potential to find iron formation type gold deposit,Tanzania. The area of gold exploration,in addition to the full ure of the country has high-resolution aeromagnetic abnormalities screening target area,but also with the ground high-precision magnetic measurement to determine the location of the banded iron formation and drilling arrangements,reference or copy Mwamola and PL9110 gold deposit prospecting experience and model,in order to obtain a good prospecting effect.