3D Geological Modeling and Grade Estimation for a Gold Deposit in Shandong Province, China

This study focuses on the grade estimation for a hydrothermal altered underground gold deposit in Shandong Province, China. First, the 3D geological model of the deposit was constructed implicitly using the drillhole data and geological maps, while the orebody enveloping surface was built explicitly through the cross sections and vertical sections. Then, within the mineralized alteration domain, the grade estimation was performed using the Ordinary Kriging (OK) and Sequential Gaussian Simulation (SGS). The key steps consist of data exploratory analysis, variogram modeling, Ordinary Kriging estimation, Sequential Gaussian simulation and model validation. For the model validation, the cross-validation was used to assess the parameters of the variogram models and the neighborhood searching, while the global statistics and the variogram of the realizations were compared to those of the original data to check the reproduce. Compared to the explicit orebody model, the kriging estimates present a more precise spatial distribution of the mineralization, and the simulated realizations provide the probability of the ore occurrence. The both models are reliable and valuable to the mining industry.