西藏甲玛矿区三维地质建模与层状矽卡岩靶区预测

    3D geological modeling and stratified skarn target prediction in the Jiama deposit, Tibet

    • 摘要: 西藏甲玛矿区是冈底斯成矿带非常典型的多金属矿床,理论预测研究认为,在矿集区深部发育隐伏的斑岩-矽卡岩矿体,而基于矿区钻孔覆盖的勘查模型对外围区潜在靶区预测程度较低。以甲玛矿区45口钻孔岩心的密度、磁性、电阻率、极化率等物性资料为基础,分析了覆盖甲玛矿集区及外围的大地电磁测深三维数据体,基于GOCAD软件平台,通过离散光滑插值法与随机模拟算法,构建了甲玛矿区的地层岩性-地球物理三维可视一体化模型;结合大地电磁测深11条剖面的二维地质解译成果,精细刻划了3000 m以浅的三维矽卡岩体发育特征,并通过使用未参与建模的甲玛科学深钻JMKZ-1进行验证,结果显示三维地质模型具有较好的一致性;基于构建的矽卡岩成矿模型,结合甲玛矿区及邻区岩(矿)石电性参数特征分析和三维矽卡岩的电性结构,预测了甲玛矿区的层状矽卡岩靶区,为深部资源潜力评价及矿集区增储目标提供三维建模技术示范。

       

      Abstract: The Jiama deposit in Tibet is a very typical polymetallic deposit in the Gangdise metallogenic belt.Through theoretical prediction and research, it is believed that concealed porphyry-skarn ore bodies are developed in the deep part of the ore-concentrated area.However, the exploration model based on the borehole coverage of the mining area has a low degree of prediction of the potential target in the peripheral area.Based on the density, magnetic properties, resistivity, and polarizability data of 45 borehole cores in the Jiama deposit, the three-dimensional magnetotelluric sounding data covering the Jiama deposit and its periphery were analyzed.Based on GOCAD software, the stratum lithology-geophysical three-dimensional visualization integrated model of the Jiama deposit was constructed through discrete smooth interpolation and stochastic simulation algorithms.Combined with the results of 2D geological interpretation of 11 magnetotelluric(MT) profiles, the development characteristics of 3D skarn bodies below 3000 m were finely depicted and verified with the Jiama Scientific Deep Drill JMKZ-1 which was not involved in the modeling.The results show a consistency agreement.Besides, based on the skarn metallogenic model, combined with the analysis of the electrical parameters of the Jiama deposit and adjacent areas, as well as the electrical characteristics of the three-dimensional skarn, the favorable target area of stratified skarn in Jiama deposit is predicted.The results can provide a demonstration of 3D modeling technology for the evaluation of deep resource potential and reserves increasing in the mining area.

       

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