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CET Grid Analysis Extension

Western Australia

CET Grid Analysis Extension: Potential fluid pathways such as shear zones and faults are often associated with magnetite-destructive alteration resulting in linear negative anomalies in magnetic data.

We have developed a new image analysis method for magnetic data that automatically maps lineaments and identifies geological structural complexity. This quantitative analysis is efficient and self consistent in dealing with large volumes of data, and is suitable as a first-pass ground selection tool for orogenic gold exploration in greenfield terrains. This software provides tools for texture analysis, contrast invariant ridge detection and edge detection algorithms, lineament vectorisation, and two scenarios of structural complexity detection, namely, contact occurrence density and orientation entropy.

An example workflow is to identify lineaments as a reliable indicator of geological structures, exploiting a combination of texture analysis and contrast invariant ridge detection to find laterally continuous textural ridges. Using the detected lineaments, two scenarios of local structural complexity are explored: contact occurrence density based on the number of faults intersections and splays; and orientation entropy representing deviations of strike of lower order faults and ductile shear zones. The local structural complexity is visualised using heat maps that highlight the regions of structural complexity. This work flow is designed to exploit the known association of Archean gold deposits with zone of complex structure adjacent to major shear zones.

Research Outcomes:
CET Grid Analysis Extension for Geosoft Oasis Montaj – commercialised software product marketed by Geosoft.

Holden, E. J., Wong, J.C., Kovesi, P., Wedge, D., Dentith, M., Bagas, L., 2012, Identifying Regions of Structural Complexity in Regional Aeromagnetic Data for Gold Exploration: An Image Analysis Approach, Ore Geology Reviews, Vol. 46, pp. 47-59.