Exploration and Geology of the Arafura Sea

Abstract

Large scale systematic exploration of the Arafura Sea started in 1965. Following an aeromagnetic survey some 4,900 miles of seismic lines have been shot by Shell in their permits, which at present occupy almost 60 percent of the total acreage.The following results have been obtained:Possible Palaeozoic sediments and certain Mesozoic and Cenozoic sediments are present in the Arafura Basin, deposited on a strongly folded and faulted pre-Cambrian basement. The Mesozoic and Cenozoic overlies the pre-Mesozoic with regional unconformity.Sedimentary thicknesses gradually increase offshore to more than 20,000 feet.During Mesozoic and Cenozoic times the Arafura Basin was affected by more or less continuous subsidence, which resulted in very little deformation. Only one small closed structure, in the Money Shoal area, has been defined.Stronger pre-Mesozoic movements, which resulted locally in the formation of a westnorthwest-eastsoutheast trending graben, are evident. Structural leads in this graben might result in possible Palaeozoic fault traps. However, the presence of Palaeozoic sediments is speculative and the structures in the graben appear to have been strongly eroded prior to the deposition of the Mesozoic.In addition to structural traps, stratigraphic trapping possibilities show some promise.

Tectonics of the Indonesian region

“…Pre-Jurassic, high-velocity strata are very thick in the area of the offshore Arafura Basin, where crystalline basement rocks may be as deep as 10,000 m, and presumably most of this section is Proterozoic (Nicol, 1970). The pre-Jurassic strata continue thick northward across much of the Arafura Sea, thence thin markedly westward toward the Aru Islands near the edge of the present shelf.…”