大兴安岭中段火山岩型铀矿多源信息分析与成矿预测

Study on Multifactorial Analysis and Metallogenic Prediction of Volcanic-type Uranium Deposits in the Middle Section of Great Hinggan Mountains

大兴安岭中段构造-岩浆活动强烈,火山岩分布广泛,铀矿(化)点、铀异常点达108处,成矿地质条件较好。受自然地理、植被覆盖等因素影响,铀矿工作程度总体较低,并未取得实质性突破。为进一步挖掘大兴安岭中段铀成矿信息开展定量化铀成矿预测,在综合分析大兴安岭中段铀成矿地质背景、典型铀矿点特征的基础上,总结了区域铀成矿控制因素;利用最新的航空放射性数据,结合地质、矿产、航磁、遥感等资料,开展铀成矿多源信息分析;选取了与铀成矿相关的地层、构造、潜火山岩、热液蚀变、航放异常信息、遥感蚀变异常、遥感解译构造等17个指标因子,基于层次分析法,建立“目标层-准则层-指标层”层次分析模型,通过构建判断矩阵,确定各评价因子的综合权重;利用GIS平台,开展了铀成矿预测,井预测铀成矿远景区13处,其中Ⅰ级铀成矿远景区1处、Ⅱ级铀成矿远景区7处、Ⅲ级铀成矿远景区5处,预测远景区覆盖了区内绝大部分已知铀矿(化)点、铀异常点。虽然预测的多个Ⅲ级远景区尚未发现铀矿(化)点,但其找矿线索较多,具有较好找矿潜力。预测结果表明,利用层次分析法开展铀成矿预测,能快速综合多源信息、提高预测精度,预测结果能为进一步铀矿工作部署提供参考。

In the middle section of the Great Hinggan Mountains,the intense structural-magmatic activity is represented by the widespread volcanic rocks,favorable uranium metallogenic condition is indicated by the 108 uranium occurrences and anomalies points.However,substantial breakthrough of uranium exploration has not been achieved by the constrain factors such as desne vegetation coverage,low exploration level in geology and geophysics.In order to further excavate the uranium mineralization information for quantitative uranium mineralization prediction,the author summarized ore-controlling factors of uranium based on geological background and characteristics of typical uranium occurrences;then combined the information in geology,minerals,airborne magnetism as well remote sensing and carried out multifactorial analyze of uranium mineralization;furthermore,the author picked out 17 evaluation factors,such as the strata,structures,subvolcanic rocks,hydrothermal alterations,airborne radioactive anomaly,remote sensing alteration anomaly.Based on analytic hierarchy process of GIS,the author established a hierarchical analysis structure model of"target layer-principle layer-index layer"to construct judgment matrix to determine the comprehensive weight of each evaluation factor.Finally 13 uranium mineralization prospects were predicted,including,one gradeⅠ,seven gradeⅡ,five gradeⅢ.All these results showed that the analytic hierarchy process can quickly synthesize multifactorial information and improve the prediction accuracy as well as provides reference for the further work plan on uranium exploration.