Publication Name: Eastern Australian Basins Symposium 2001
Authors: M.R. Power, K.C. Hill, N. Hoffman, T. Bernecker and M. Norvick
Date Published: November 2001
Number of Pages: 35
Reference Type: Magazine Article
Abstract:
The Gippsland Basin has been Australia's main hydrocarbon producing province since the mid- 1960's, yet many questions remain concerning the basin's evolution. Interpretation and depth conversion of more than 4,000 km of 2D regional seismic, inclnding generation of 15 regional horizon maps from Palaeozoic to Late Tertiary has allowed development of a 3D structural model for the offshore Gippsland Basin and the deep-water Bass Canyon region. To quantify extension, regional 2D depth sections were generated from the model then back-stripped,balanced and restored. The main results are:
? The first rift phase resulted in at least 30% crustal extension and formed an extensive system of grabens and half-grabens comprising the Central Deep, connected to branching rifts across the present-day Northern Strzelecki Terrace, and eastwards towards the Gippsland Rise.
? The second rift phase was focused in the eastern Central Deep, Eastern Graben and Southern Graben resulting in at least 5% extension, which obliquely reactivated the earlier fault networks of the first rift phase.
? Continued post-rift subsidence from the Campanian to Recent has been focused over the reactivated depocentres of the second rift phase. The interplay between ongoing subsidence, carbonate deposition and strong erosional events resulted in the present-day configuration of the Gippsland Amphitheatre and Bass Canyon.
? The complex evolution of the basin, characterised by reactivation and repeated post-rift subsidence has overprinted any remnant deep-basin forming detachment.
? Based on the structural style of the modelled Strzelecki rift, in areas that are better resolved by seismic, the deep basin structure beneath the Central Deep is anticipated to comprise a similar ENE-WSW trending network of basement highs and tilted half-grabens