基于证据权重法的雪峰山中段金矿矿集区找矿远景预测

The gold metallogenic prognosis based on the weighting method of evidence in the middle Xuefeng mountain area

雪峰山中段是湖南省重要的金矿聚集区,具有较大的找矿潜力。为寻找新的找矿远景区,在系统总结研究区成矿规律的基础上,重新建立了金矿找矿模型。确定的11个证据因子包括青白口系、下南华统、韧性剪切带、断层缓冲区0.5 km、褶皱缓冲区1.0 km、岩体外接触缓冲区2 km^8 km、As、Sb、Au、Pb和W水系化探异常等。依据上述证据因子,这里首次采用MRAS中的证据权重模型对研究区金矿进行了成矿远景预测工作。 本次预测采用0.5 km×0.5 km的网格进行后验概率计算,确定3个级别的网格区块,分别为A、B和C。圈定4处找矿远景区,根据找矿远景区面积、后验概率平均值、赋矿地层及已发现矿床(点)数量对找矿远景区进行分级,确定I级找矿远景区2处,Ⅱ级找矿远景区1处和Ⅲ级找矿远景区1处。综合分析后认为,I级找矿远景区内部的A级网格区块具有较好的找金潜力,是本区今后找矿的重点突破的区域。

As an important gold accumulation area in Hunan province, the middle part of Xuefeng mountain has a great prospecting potential. In order to find new prospecting target area, the gold ore prospecting model was reestablished on the basis of systematically summarizing the metallogenic regularity of the study area. Eleven evidence factors, including Qingbaikou system, Lower Nanhua system, fault, ductile shear zone, fold, 2 km^8 km exocontact of the granite mass, and anomaly of stream sediment of Au, As, Sb、Pb and W are revealed. Based on the above evidence factors, the evidence weighting model in MRAS is used to predict the metallogenic prospect of gold deposits in the study area. This prediction uses 0.5 km×0.5 km grid for posterior probability calculation to determine 3 levels of prediction blocks, A, B and C, respectively. According to the area of the 4 prospecting targets, the average value of posterior probability, the number of ore bearing strata and the number of the discovered ore deposits, the prospecting targets were classified. We determined 2 I level prospecting target areas, 1 Ⅱ level prospecting target areas and 1 Ⅲ prospecting target areas. After comprehensive analysis, it is considered that the Class A prediction block within the Class I prospecting target has good potential for gold prospecting and is a key breakthrough area for future prospecting in this area.