Using a 3D geological mapping framework to integrate AEM, gravity and magnetic modelling - San Nicolas case history

Abstract

We present an example of the use of a software framework that combines 3D geological mapping and geophysical modelling. This approach would be relevant in a wide range of applications, from regional geological mapping, groundwater studies, through to mineral or geothermal prospecting. In this instance, we illustrate a typical workflow with a case study involving the San Nicolas VMS deposit and surrounding region. An initial 3D geological map, based on sparse surface geological observations, is progressively refined using AEM and potential field modelling results. At each stage, the geological map is used to capture and communicate the inferred distribution of map units. During the latter stages of interpretation, the geological map is also used to provide constraints for potential field modelling. In addition to the opportunity for direct detection of highly conductive basement-hosted sulphide mineralisation, the availability of AEM data proved crucial in the San Nicolas example in that we were able to use these data to determine the thickness of a moderately conductive transported cover unit. This significantly reduced the ambiguity of subsequent potential field interpretations.