基于GIS的证据权重法在成矿预测中的应用——以甘肃省岷县—礼县地区的金矿预测为例

APPLICATION OF GIS-BASED EVIDENCE WEIGHT METHOD FOR MINEROGENETIC PREDICTION:A CASE STUDY ON PREDICTION OF GOLD DEPOSIT IN MIN COUNTY AND LI COUNTY REGION,GANSU PROVINCE

在深入了解甘肃省岷县—礼县地区金矿成矿特征的基础上,以地理信息系统(GIS)为平台,对该区进行成矿分析后认为中泥盆统李坝群、中泥盆统西汉水组和中石炭统下加岭组为成矿的有利地层组合;金矿床(点)多出现于花岗岩体外接触带距岩体边缘0.5～5.0km范围内的黑云母化蚀变带中;半径为1.61km的断层影响带为最佳的有利成矿的断层影响范围;Au-As-Ag-Sb-Pb为成矿的有利地球化学元素异常组合。利用GIS的空间分析功能,分别提取了上述各成矿有利因素,进而建立了证据权重模型,选择了地层、岩体、断裂、化探等11个证据因子。在此基础上,根据该区成矿概率的分布进行了成矿远景区的预测,共圈出了7个成矿远景区: .中川岩体北侧; .中川岩体东侧以及中川岩体与碌碡坝岩体所夹区域; .闾井岩体南侧; .教场坝岩体南侧; .碌碡坝岩体西侧; .教场坝岩体东侧; .柏家庄岩体南侧。其中前4个远景区覆盖了几乎所有的已知金矿床(点),而后3个远景区目前还未发现金矿床(点),预测结果对于该区的进一步找矿具有一定的指导意义。

Based on the comprehensive analysis of gold mineralization in Min County and Li County region,Gansu Province,with GIS as the platform,we have come to the following conclusions:Liba Group and Xihanshui Formation of Middle Devonian and Xiajialing Formation of Middle Carboniferous are the combination of beneficial strata,with the gold deposits mostly located in biotite zone of outer contact aureole of terranes where the distance is about 0.5~5.0 km;the radius of beneficial belt of fault is 1.61 km;AuAsAgSbPb is beneficial anomaly of chemical element combination.Using the spatial analysis of GIS,we have built the evidence weight model and chosen 11 evidence factors,including strata,terrane,fault,geochemical anomalies of Au,As,Ag,Sb,Pb and so on.Finally,we have predicted favourable areas according to the ore formation probability values.The prediction shows 7 minerogenetic prospective areas.Ⅰ.North of Zhongchuan terrane;Ⅱ.East of Zhongchuan terrane and the interspace of Zhongchuan and Luzhouba terrane;Ⅲ.South of Lujing terrane;Ⅳ.South of Jiaochangba terrane;Ⅴ.West of Luzhouba terrane;Ⅵ.East of Jiaochangba terrane;Ⅶ.South of Baijiazhuang terrane.In these areas,Ⅰ,Ⅱ,Ⅲ and Ⅳ areas have covered all known gold deposits and Ⅴ,Ⅵ and Ⅶ have not yielded gold deposits,which should be specially emphasized.The conclusion of prediction has some indiction for further orefinding of this area.