ABSTRACT: Enhancing aeromagnetic data from sedimentary basins using texture-based filtering

Dentith, Mike¹, and Duncan Cowan²
(1) University of Western Australia, Perth, Australia 
(2) Cowan Geodata Services, Perth, Australia

In the last 10 years the major advance in geophysical exploration for minerals has been in the use of aeromagnetic data. Improvements in instrumentation and the presentation of the data have allowed higher and higher resolution datasets to be collected. The resulting data are presented as various images that appear very like large-scale geological maps. The result has been that such datasets are now routinely collected in mineral exploration and every geologist must be able to interpret such data.

Magnetic surveys are most effective when there are significant contrasts in magnetisation between the various rock types in the survey area. The surveys were initially applied to Archaean greenstone belts, where this is the norm, mainly for stratigraphic and structural mapping for gold exploration. However, the success in this environment has led to surveys in other mineralised environments, including sediment-hosted mineralisation such stratiform copper deposits and Mississippi Valley-type base metal deposits. The lower levels of magnetisation within the sedimentary host rocks for such deposits has required specific data processing/enhancement techniques to be developed for highlighting very subtle changes in rock magnetism. The authors have had much such success using a texture-based filtering methodology based on "grey-level co-occurrence matrices". These same methods are now being applied to high-resolution aeromagnetic surveys collected during exploration for hydrocarbons. The techniques have been found to work well, highlighting far more structural and stratigraphic information in the datasets than conventional image enhancement techniques such as the calculation of derivatives. The methodology will be demonstrated using a dataset from the Perth Basin, offshore Western Australia.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia