Applying conceptual geometrical models in evaluating mineral prospects

Continuity of geology and grade are key traits that must be demonstrable during the process of estimating a reportable Mineral Resource. Too often, however, assay grade takes precedence in interpreting the so-called geological model, while the geology – lithology, structure and alteration – are vastly underused or even ignored during the modelling process. This can lead to a follow-the-dots (grade) geological model in which little or no thought has been devoted to the actual likelihood of the grades being linked according to the model.

Over the years, SRK has encountered numerous projects where seemingly simple geological models, based on grade alone, have become unstuck at a later phase of exploration, evaluation or production. By paying careful attention to the geological structures in drillholes and by applying a relevant empirical geometrical relationship or conceptual geometrical model to the geology of the deposit, the geologist can produce a more accurate reflection of the geology in the 3D models used in Mineral Resource Estimates.

Because SRK’s Structural Geologists are highly qualified and have conducted technical evaluations on many deposit types, their experience allows them to draw on conceptual models of the geometry or controls on mineral deposits and a case book of real-world examples. This breadth of experience is particularly useful in the exploration stage, where geometrical information is scarce.

Knowledge and project experience bring a sound footing for the accurate interpretation of geological data and the means to interpret the continuity of mineralised veins and dykes, folded geological bodies and stratiform deposits with increased confidence, lowering the overall project risk.

Recent examples have included:
• the interpretation of complex vein-fault relationships in an epithermal Au-Ag deposit to explain the variable exploration intercepts, and to assist in defining geological domains for the Mineral Resource Estimate.
• using conceptual models of vein geometry and growth to assist in the characterisation and likely impacts on mining of a significant gemstone deposit.
• identifying pre-lithification deformation in sediments from drillholes and reinterpreting drill sections in a large, early-stage bulk commodity exploration.

Chris Bonson: cbonson@srk.co.uk


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