MARGIN-SCALE, BASEMENT-INVOLVED COMPARTMENTALISATION OF AUSTRALIA'S NORTH WEST SHELF: A PRIMARY CONTROL ON BASIN-SCALE RIFT, DEPOSITION AL AND REACTIVATION HISTORIES

Abstract

Australia's North West Shelf is segmented into four discrete margin-scale compartments which have distinct rift and reactivation histories. Two of the margin segments, the Carnarvon and Bonaparte compartments, are very wide (500–600 km), marginal plateau systems, whereas the other two segments, the Canning and Browse compartments, are narrower and steeper. The boundaries between individual rift compartments appear to be controlled by Proterozoic fracture systems.The Browse-Bonaparte transition zone is a major, northwest-trending Proterozoic fracture system which has a series of igneous intrusions along its length. These intrusions are located where the fracture system is cut by younger, northeast-trending extensional faults. This transition zone is a margin-scale fault relay zone, with intense fault overlap along the transition resulting in the zone being a long-lived, syn-rift high. Moreover, the transition zones between adjacent wide and narrow margins are prime locations for the entry point of siliciclastics into the rift or post-rift margin system. As a result, well-developed channel systems often cut through these boundaries and high quality reservoirs (particularly low-stand fans) are developed.Neogene fault reactivation, associated with convergence of the Australasian and Eurasian plates, is evident along the North West Shelf. The style of this reactivation is, however, closely controlled by the margin- scale architecture. In the Browse and Carnarvon basins, Neogene inversion is common, but at the leading edge of the collisional system, the Bonaparte compartment, the fault style is exclusively extensional. It appears that lithospheric flexure, associated with localised foreland development (i.e. the Timor Trough), has been the driving mechanism for the extensional faulting within the Bonaparte compartment. Crustal convergence seems to have been accommodated completely by thrusting on the northwestern margin of Timor and by foreland formation. In contrast, the Browse and Carnarvon compartments lacked a 'buffering' foreland system and, being adjacent to rigid and thin oceanic crust which transmits stress well over long distances, the inversional stresses were transmitted directly into these compartments.As a result of these margin-scale processes, the Bonaparte compartment is characterised by a thin regional seal (often 100 ms) on Neogene extensional faults—a combination which strongly favours fault seal failure and trap breach. In contrast, the Browse compartment is characterised by thick seals and small displacement Neogene faults, and thus the probability of fault seal failure is much less.

Yampi Shelf, Browse Basin, North-West Shelf, Australia: a test-bed for constraining hydrocarbon migration and seepage rates using combinations of 2D and 3D seismic data and multiple, independent remote sensing technologies

“…2): the Timor and the Browse compartments (O'Brien et al, 1996b(O'Brien et al, , 1999. The boundary zone between these two compartments is a fundamental, north-west trending Proterozoic lineament or fracture system, which has acted as a long-lived fault relay zone.…”

Geomorphological evidence for late Quaternary tectonic deformation of the Cape Region, coastal west central Australia

“…Table 1 Literature that present data for Quaternary tectonic deformation the Carnarvon Basin. Raggatt (1936), Clarke (1938), Teichert (1948), Condon et al (1955), Condon et al (1956), McWhae et al (1956), Boutakoff (1963), Raynor and Condon (1964), Baxter (1967), Wyatt (1967), Hancock (1969), Allen (1972b), van de Graaff et al (1976), Denman and van de Graaff (1977), Veeh et al (1979), Megallaa (1980), Hocking (1985), Hocking et al (1987), Hocking (1988), Malcolm et al (1991), Kendrick et al (1991), Wyrwoll et al (1993), Baillie and Jacobson (1995), Crostella (1995), Logan (1987), Crostella and Iasky (1997), Keep et al (1998), O'Brien et al (1999, Keep et al (2000), Ellis and Jonasson (2001), Hearty et al (2002), Keep et al (2002), Longley et al (2002), Cathro and Karner (2006), Clark (2006), Keep et al (2007), Hillis et al (2008), Revets et al (2009) Although there are two contrasting views presented in the literature, it is misleading to characterize the opposing views as comparable in terms of their breadth and volume of research. We have found only two published papers that specifically interpret data from the Cape Region as indicating tectonic stab...…”

Deformation of the Cablac Mountain Range, East Timor: An overthrust stack derived from an Australian continental terrace

“…1) reflects the pre-collisional geometry of the Bonaparte Basin has also been proposed (O'Brien et al, 1999;Keep et al, 2003;Fig. 10;Harrowfield and Keep, 2005), and is generally accepted from both stress and strain data (O'Brien et al, 1999;Hillis et al, 1997;Hillis and Reynolds, 2000;Harrowfield et al, 2003;Harrowfield and Keep, 2005). Furthermore, various workers have previously suggested that an outlier of Australian continental crust collided with the subduction zone at some point prior to the main collision (e.g., Richardson and Blundell, 1996;Keep et al, 2003;.…”

“…15), and became incorporated into the orogenic wedge generated by the collision. Similarities between the inherited rift architecture of the Carnarvon and Bonaparte basins have been previously recognised (O'Brien et al, 1999;Harrowfield et al, 2003;Harrowfield and Keep, 2005), especially in terms of their upper-plate/lower-plate extensional geometries (Lister et al, 1986;O'Brien et al, 1999). That the Carnarvon Basin (Fig.…”

“…That the Carnarvon Basin (Fig. 1) reflects the pre-collisional geometry of the Bonaparte Basin has also been proposed (O'Brien et al, 1999;Keep et al, 2003;Fig. 10;Harrowfield and Keep, 2005), and is generally accepted from both stress and strain data (O'Brien et al, 1999;Hillis et al, 1997;Hillis and Reynolds, 2000;Harrowfield et al, 2003;Harrowfield and Keep, 2005).…”