Rapid assessment of structural geometries for brownfield targeting, Burkina Faso

An understanding of the structural controls on zones of mineralisation is of fundamental importance for brownfield exploration efforts. The combination of field geology observational skills with new, rapid, computerised modelling tools enhances SRK’s ability to provide rapid three-dimensional answers to clients. SRK’s Vancouver office has been fairly active in gold projects in Burkina Faso, including the Tanlouka project on the Markoye shear zone in the central-east of the country, the Youga deposits in the southeast and the Nami gold zone of the Karma deposit in the Goyen greenstone belt in the western part of the country.

In Burkina Faso, SRK is typically tasked to explain the timing of the possible gold mineralising events relative to the Paleoproterozoic Eburnean deformational history, and to define the controlling structural geometries on the mineralisation. Mineralisation often occurs early relative to deformation, and gold may be deposited or mobilised more than once. Fundamental structural observations of deformation timing is key to determining the possible large- and small-scale geometries of mineralisation. Available data varies between projects, but may be derived from mapping and/or drill core. Rapid visualisation of zones of mineralisation and rapid modelling is very valuable before, during and after the site visit, during the post-visit interpretation (see figure above).  

We typically use software to evaluate the distribution of mineralisation intersected in existing drill holes before the site visit, in order to select the key drill holes that require observation, based on preliminary interpretation. During the site visit, drill core observations of structural deformation textures, cross-cutting relationships, as well as orientated core measurements of structural geometries are used to test and continue the interpretation of the mineralisation timing and geometry. The observations are immediately integrated back into 3D to continuously develop and test the 3D models. Leapfrog’s AranzTM (ARANZ Geo Limited) accelerated wireframing capability allows geologists to demonstrate to the client a 3D structural interpretation and a tangible product even before the site visit ends. Preliminary ideas on further drill targeting can be presented and debated with the project geologists.

The integration of structural observational skills and new advanced 3D modelling tools is a successful combination that improves SRK’s ability to add value to our clients in brownfields exploration.

Wayne Barnett: wbarnett@srk.com

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