Interaction Between Faults and Igneous Intrusions in Sedimentary Basins: Insights from 3D Seismic Reflection Data

Magee, Craig¹; Jackson, Christopher A.¹; Schofield, Nick²
¹Department of Earth Sciences and Engineering, Imperial College London, London, United Kingdom.
²School of Geography, Earth and Environmental Science, University of Birmingham, Birmingham, United Kingdom.

Normal faults and igneous intrusion complexes can individually influence sedimentary basin evolution and petroleum system development through compartmentalisation, trap formation and the generation of hydrocarbon migration pathways. Whilst our understanding of fault and intrusive systems continues to improve separately, few studies have considered the interaction of the two and the potential impacts on petroleum system development. Here, we present 3D seismic reflection interpretations detailing the relationship between saucer-shaped sills and faults within the Exmouth sub-basin located offshore NW Australia. Transgressive sill segments are frequently observed to preferentially exploit specific pre-existing faults, potentially forming localised seals. Furthermore, mound-shaped structures, interpreted to represent hydrothermal vents, are often developed above the upper tips of the faults that are intruded by the sills. We consider how the fault seal potential, which is related to fault throw and the physical properties of the faulted lithologies, controls the styles of both intrusive magmatic and extrusive hydrothermal products. This study demonstrates the complex interactions that may occur between normal fault arrays and igneous systems, and highlights how fluid migration pathways and hydrocarbon traps may be modified in petroliferous basins.

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012