Tonnage Uncertainty Assessment of Vein-Type Deposits Using Distance Functions and Location-Dependent Correlograms

APCOM 2009
Michael J. Munroe, Clayton V. Deutsch ,
Abstract Modelling the geometry of a vein is a crucial step in resources estimation. The resulting models are used as mineralization domain boundaries and have a direct impact on the tonnage of estimated resources. Deterministic models are often built using time consuming wireframing techniques usually based on hand interpretation of the drillhole intercepts. Another approach consists in coding the drillhole samples by a function of their distance to the veins contacts. The coding is subsequently used for modelling the vein contacts away from drillholes. This is a more efficient approach and is able to provide a measure of tonnage uncertainty. The use of location-dependent variograms improves the modelling by incorporating local changes in the anisotropy of the vein structure. This combined approach results in more realistic vein models, particularly when the geometry of the vein has been are altered by folding, shearing and other structural processes. This numerical approach is explained in detail with illustrative examples. Then, the proposed approach is applied to a realistic case study.
Keywords: Geostatistics, Distance Functions, Uncertainty, Resources Estimation, Geological modelling, Variograms, Vein deposits
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