Insights into the petroleum potential of the Australian North West Shelf and Arafura Sea revealed by regional 2D seismic data.

Abstract

TX 75083-3836, U.S.A., fax +1-972-952-9435

Reconciling regional continuity with local variability in structure, uplift and exhumation of the Timor orogen

“…Unit thicknesses match those that we map at the surface of Timor: 1 km each for the Permian and Triassic stratigraphy and 800 m for the Kolbano Sequence. It is possible that there is undocumented thickness variation of Gondwana Sequence strata deformed below Timor, as thickness variations and normal faulting are found on the present Australian shelf (Tripathi et al, 2012;Baillie and Milne, 2014;Saqab et al, 2017). We do not incorporate such thickness variations in this cross section, however, as a) thickness variation is not seen in the units mapped on land, so any schematic thickness variation in the subsurface would be highly conjectural, and b) similar unit thicknesses in Timor-Leste (Tate et al, 2015) and in some places on the Australian shelf (Karig et al, 1987;Snyder et al, 1996) suggest generally consistent thicknesses at a broad scale despite local thickness variations.…”

“…We therefore interpret thin-skinned deformation in the subsurface, as we consider it the most kinematically feasible and the most consistent with the surface geology. Seismic data offshore Timor (Tripathi et al, 2012;Baillie and Milne, 2014;Saqab et al, 2017) clearly demonstrate the plausibility of deforming strata that are cut by normal faults into thin-skinned thrust stacks, as the youngest Australian margin strata are observed to contain normal faults south of the Timor Trough and form a thin-skinned thrust stack north of the Timor Trough. Also, thin-skinned deformation similar to what we have interpreted in Timor is evident in shortened continental margin strata of Taiwan (Suppe, 1981), another prominent setting of active arc-continent accretion.…”

“…Seismic reflection data indicate that the modern Australian margin south of the Timor Trough contains numerous normal faults cutting stratigraphy correlative to the Gondwana Sequence (Tripathi et al, 2012;Baillie and Milne, 2014;Saqab et al, 2017). With the notable exception of large extensional basins such as the Vulcan Graben, the majority of these normal faults appear to have offset less than the ap-proximately1 km stratigraphic thicknesses of each of the Gondwana Sequence units.…”