ABSTRACT: Arafura Sea Aeromagnetic Interpretation, Reconciliation with Subsequent Seismic Data

WHITING, THOMAS H., BHP Minerals Exploration, Hampton, Victoria, Australia

During 1988 a high resolution aeromagnetic survey was flown covering 65,000 sq km of the Arafura Sea. The prime purpose of the survey was to define the regional tectonic structure and estimate the thickness of sediments allowing prospective basins and subbasins to be outlined, aiding planning of subsequent seismic reflection surveys.

Aeromagnetic interpretation shows the eastern part of the region is dominated by a major northwest trending graben which has been subsequently displaced by extensive northeast trending dextral strike-slip fault systems. Seismic data indicates this graben formed mainly during the Paleozoic and confirms that the strike-slip faulting caused major offset of the graben and folding and fault disruption of the Paleozoic sediments.

The central part of the survey area forms a stable basement shelf while the western region is dominated by a complex NS trending fault system, and a number of east-west trending normal faults. The former structure is the extension of the Tom Turners Fault system

which is part of the Halls Creek Mobile belt. Good correlations are found between depth to magnetic basement and interpreted seismic depth to Precambrian crystalline basement throughout the area. However structures outlined from aeromagnetic interpretation have dominantly influenced the pre-Mesozoic sedimentary section with less influence on Mesozoic sedimentation.

Four spatially separate magnetic provinces form the magnetic basement to overlying nonmagnetic sediments. Each appears to be associated with a different character on seismic reflection sections.

The structural setting and sediment thickness obtained from aeromagnetic data was useful in planning subsequent seismic surveys and shows a good correspondence with that obtained from subsequent seismic data. However detailed comparisons indicate that the aeromagnetic data has been underutilized, as unique insights can be obtained concerning the orientation and nature of regional structures not easily obtained from the seismic data.

AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)