三维地质模型不确定性分析及对三维成矿预测结果的影响解析

Uncertainty of 3D Geological Modeling and its Influence on 3D Mineral Prospectivity

三维地质模型是三维成矿预测最重要的数据基础之一,其准确性对于深部预测靶区的圈定具有十分重要的意义。然而,三维地质模型存在一定程度的不确定性,其不确定性主要是受到地质体与地质结构自身的复杂性,数据密度、误差和建模方法等多方面影响。本文以长江中下游成矿带钟姑矿田为例,基于隐式三维地质建模及蒙特卡洛模拟方法,对控制剖面中地质界线产状引起的三维地质模型的不确定性开展定量分析,并度量和评价其对三维成矿预测结果的影响。研究结果显示,深部地质界线的产状倾角及倾向变化会导致三维地质模型产生不同程度的不确定性。通过扰动策略,能够有效开展相关的不确定性分析和度量工作;三维地质模型的不确定性会在一定程度上影响三维成矿预测结果,但三维成矿预测方法具有一定的鲁棒性,基于预测结果圈定的找矿靶区位置相对稳定。对于具有较高不确定性的深部预测靶区,进一步工作可通过降低三维地质模型的不确定性或增加其他预测信息等方式,提高预测结果的确定性,以降低找矿勘探风险。

Three-dimensional(3D)mineral prospectivity delineates the target mining area based on 3D geological model.The 3D geological model is the foundation of 3D mineral prospectivity.Due to the complexity and diversity of geology itself,data errors,modeling methods,and other factors,3D geological model is bound to have uncertainty that will directly affect the target area of 3D mineral prospectivity.The Zhonggu iron orefield located in the middle and lower Yangtze metallogenic belt of Eastern China is taken as an example to research the influence of the uncertainty of the 3D geological model on 3D mineral prospectivity.Based on the implicit modeling method and Monte Carlo simulation method,a set of geological models are generated by randomly disturbing the strike and dip direction of the geological boundary.By using the 3D spatial analysis method and logistic regression method,the prospecting target area is prospected through the relevant ore-controlling and indicator elements,and analyzing the influence of the uncertainty of the 3D geological model.Research shows that the change of the strike and dip direction will influence 3D geological model and the results of 3D mineral prospectivity.The disturbance strategy described in this paper can effectively analyze and measure the uncertainty.The uncertainty of 3D geological model will affect the results of 3D mineral prospectivity.At the same time,the 3D mineral prospectivity method has certain robustness,and the 3D prediction results are relatively stable in delineating the prospecting target area.To reduce the uncertainty of the 3D mineral prospectivity and reduce the risk of prospecting and exploration,further work should be done to reduce the uncertainty of the 3D geological model or increase the ore-controlling and indicator elements in the 3D spatial analysis.