岩屑地球化学测量在甘肃北山干旱戈壁荒漠区的找矿效果--以三白墩地区金砷矿的发现为例

Application of geochemical survey of lithic fragments in ore prospecting in arid Gobi desert of the Beishan area,Gansu Province:A case study of the discovery of the gold-arsenic deposit in Sanbaidun area

在甘肃北山干旱戈壁荒漠景观特征研究的基础上,对三白墩地区进行1∶5万水系沉积物测量,圈定水系综合异常10处。优选AS-3异常,采用100 m×20 m的网度,在1/3线距范围内多点采取2~20 mm粒级岩石碎屑的方法进行详细检查。圈定岩屑综合异常3处,对异常特征进行研究,确定主成矿元素为As、Au,并优选综合异常2个。利用地球化学剖面、槽探等方法进行详细检查,发现Au矿体4条,As矿体2条,Au、As矿化体各1条,显示出该方法在甘肃北山干旱戈壁荒漠景观区找矿中具有较好的找矿效果,同时也说明可以运用1∶1万岩屑测量对1∶5万水系沉积物测量的异常进行查证。

Based on the landscape characteristics of the arid Gobi desert in the Beishan area,Gansu Province,this study carried out a 1∶50,000 stream sediment survey in the Sanbaidun area and delineated 10 integrated anomalies.Then,the As-3 anomaly was preferentially selected for detail inspection by taking lithic fragments with grain sizes of 2~20 mm at multiple locations within 1/3 line spacing using a grid density of 100 m×20 m.As a result,three integrated anomalies of lithic fragments were delineated and their characteristics were investigated.The dominant ore-forming elements were identified as As and Au,and two integrated anomalies were preferentially selected for detailed inspection using methods such as geochemical profile and trenching.Consequently,four Au orebodies,two As orebodies,one Au mineralized body,and one As mineralized body were found.The prospecting results indicate that the geochemical survey of lithic fragments can achieve ideal prospecting effects in the arid Gobi desert landscape area of Beishan and that 1∶10,000 surveys of lithic fragments can be used to verify the anomalies of 1∶50,000 stream sediment surveys.