The Arafura Basin contains a sequence of Palaeozoic rocks lying north-east of Darwin, and which extends from onshore Australia, to perhaps as far as the Irian Jaya mainland. There are over 9 km of Palaeozoic rocks preserved along the southern bounding fault of a major graben (the Arafura Graben) located in the southern part of the basin. In the uplifted centre of the graben, there is less than 3 km of the Palaeozoic section preserved. The basin is underlain by a Middle to Late Proterozoic sequence which thickens to the east, and is probably equivalent to the onshore McArthur Basin. Overlying the Arafura Basin is the Mesozoic Money Shoal Basin, which is approximately 1 km thick over the central parts of the graben, thickening rapidly to the west and thinning to the east and north. The structural cross-section that has been drawn is located entirely offshore. It has been compiled using modern seismic and well control. It runs from south-east of Tasman 1 in a general north and north-east direction tying with Torres 1 and Arafura 1. It passes through the central and north-eastern parts of the graben, and the north-eastern part of the basin. Two-way time to depth conversions were based on the velocity surveys from the wells within the graben, but were modified locally outside the graben. The structural analysis presented is largely based on the evidence found along the line of the section. A more complete structural analysis would require a regional examination of the entire seismic network. Information from the recently published Petroleum Basin Study on the Arafura Basin (Northern Territory Geological Survey) has been incorporated into this report, although there are major differences between some of their findings and the interpretations presented here. To date the major risk in hydrocarbon exploration has been finding adequate reservoir conditions and seal. Contradictory interpretations are present between the maturation and structural modelling of the graben. Untested plays include possible Permian and Triassic sediments (up to 5 km thick) which exist along the flanks of the graben and which will probably contain good source potential and improved reservoir conditions. To the north outside the graben, there are poorly explored areas where it is speculated that there are thick Palaeozoic and Proterozoic sequences.

25% coverage to nth east corner 22-1/E51-16/7 Vertical scale: 100

22-1/H55-10/1 Contour interval: 2

22-1/F50-8/6 Vertical scale: 1200

< 5% missing sth west corner 22-1/G50-13/3

30% coverage nth east SD51-3 & 8% coverage nth west SD51-4 RMI = residual magnetic intensity 22-1/D51-4/2 Contour interval: 0

60% coverage east 22-1/G49-8/4

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