3D geological modelling and uncertainty analysis for 3D targeting in Shanggong gold deposit (China)

Abstract

Three dimensional (3D) deposit-scale modelling was used to identify exploration targets at depth and evaluation of mineral resources including 3D geometry and attribute models. Constructing 3D deposit-scale model need to combine exploration boreholes, cross-sections, and geochemistry assays additional mining dataset. The Shanggong gold deposit is a magmatic hydrothermal deposit with an orogenic setting, and it is located in the south margin of North China Craton. On basis of the geological features of the Shanggong gold deposit, the 3D geology model and attribute modelling aims at potential targets identification and mineral resource estimation adopting different mining and exploration datasets and uncertainty analysis in 3D space. The methodology is summarized as follows: 1) the 3D geological bodies, such as stratum, fault, ore bodies model, constructed using GoCAD software, an initial range of 3D model is 15 × 13 × 3 km3; 2) Ordinary Kriging and discrete smooth interpolation (DSI) methods were used to analyze and identify the trend of the mineralization (Au) features in 3D space combined boreholes and the primary geochemical haloes dataset, and the Au/Pb ratio model is constructed using primary geochemical haloes data with DSI interpolation method; 3) the grade simulation modelling and assessing the uncertainty of the geometry and feature models using the geostatistical method. The results show as follows: 1) the high gold grade value zones are associated with intrusion and NE-trending and NNE-trending cross fault structures; 2) the high gold grade value blocks of Au/Pb ratio can be used to depict mineralization zones; 3) Ordinary Kriging and DSI methods can show the trend of the attribute model; 4) the simulation results can characterize the uncertainty of the 3D model through uncertainty analysis.