基于MRAS证据权重法的辽西锦州—阜新金矿化带金矿潜力评价

Potential gold evaluation with weighting of evidence based on MRAS in Jinzhou——Fuxin gold metallogenic belt, western Liaoning Province, China

利用已有的地质、矿产、物探及化探等资料,建立锦州—阜新金矿化带基于GIS的空间数据库。在此基础上重新建立研究区金矿区域找矿模型,其中主要找矿标志包括太古宙变质岩系、北东向及东西向韧性剪切带、北东—北北东及北西向断裂、Au-Ag-Cu-Zn化探异常、金重砂异常、航磁磁感应强度-T异常在50 nT至150 nT区间内、已发现金矿床(点)。以上述找矿标志构置预测变量(证据因子),采用MRAS(矿产资源评价系统)中的证据权重模型,对研究区首次进行基于GIS下的金矿产资源评价工作。以2 km×2 km网格为单元计算得到后验概率(P),根据P将研究区成矿远景分级并确定A,B和C 3个级别预测远景区。根据远景区分布特征,将其最终划分为19个找矿靶区,其中,A级找矿靶区3处,B级找矿靶区6处,C级找矿靶区10处。

Firstly,the spatial database of Jinzhou-Fuxin gold metallogenic belt was set on the basis of the previous geological,mineral,geophysical and geochemical materials.Then,the regional gold prospecting model of the study area was built.The main prospecting criteria include Archean metamorphic formation,the NE-EW-trending ductile shear belt,the NE—NNE—NW-trending fracture,the Au-Ag-Cu-Zn geochemical anomaly,the gold heavy sand anomaly,the aeromagnetic（-T） anomaly zone from 50 nT to 150 nT and the discovered gold deposit.According to the criteria,the predictive variables（evidence factors） were established and the gold potential of the study area with weighting of evidence based on MRAS was evaluated.Finally,the posterior probability（P） of every 2 km×2 km grid unit was calculated and the study area was classified into A,B or C level prospecting areas.The results show that there are 19 prospecting targets circled according to the distribution characteristics of prospecting areas,including 3 A-level targets,6 B-level targets and 10 C-level targets.