Inversion around the Bass Basin, SE Australia

Abstract

Regional seismic reflection and fission track thermochronological studies of the Bass Basin area illustrate two types of inversion, both confined to the Bass failed rift. The first type involved 1-2 km of uplift, denudation and cooling of basement over more than 200 km along both margins of a failed rift, with lesser erosion within the rift basin. This occurred during renewed extension that bypassed the Bass Basin area leaving it as a failed rift. The uplift resulted from breaking of the lithosphere and may have been due, in part, to rebound following several kilometres of rapid sediment loading in the preceding 20 Ma. The second type comprised repeated structural inversion involving 1-3km of uplift by compressional reactivation of extensional faults and along new reverse faults. These inversions occurred along the zone of maximum extension in a failed Mesozoic rift, such that Tasmania acted as a buttress to compression. The rifting and structural inversions are interpreted to have been controlled by a long-lived zone of weakness, perhaps overlying a Palaeozoic greenstone belt, with the maximum principal stress being roughly perpendicular to faults within the zone during inversion. Significantly, Miocene-Pliocene inversion resulted from the Australian craton being placed into compression following arc collision 3500km to the north, emphasizing the importance of long distance transmission of compressional stresses through the lithosphere.

Paleothermal and seismic constraints on late Miocene–Pliocene uplift and deformation in the Torquay sub-basin, southern Australian margin

“…The volcanogenic clastic rocks were largely derived from contemporaneous dacitic volcanism (Duddy 2003). A major stratigraphic break at the top of the Eumeralla Formation records a regional uplift and exhumation episode, constrained by AFTA studies as beginning between 100 and 95 Ma that affected large areas of southern and eastern Australia (Duddy 1994(Duddy , 2009Hill et al 1995).…”

“…One such passive margin that has witnessed appreciable post-rift intraplate deformation is the southeastern Australian continental margin (Hill et al 1995;Dickinson et al 2002;Hillis et al 2008a) (Célérier et al 2005). In southwest Victoria, the remnants of early Pliocene strandlines that developed when sea levels were ~65 m higher than present-day levels now occur at elevations of ~180 m ASL, indicating >100 m of post-early-mid Pliocene uplift (Sandiford et al 2004;Wallace et al 2005).…”

Impacts of Neogene-Recent compressional deformation and uplift on hydrocarbon prospectivity of the passive southern Australian margin

“…During the early Cretaceous, the Shipwreck Trough and Torquay-sub basin were both part of a major continental rift system that encompassed the Otway, Bass and Gippsland basins (Duddy, 2003). At the end of the early Cretaceous (~95 Ma), some parts of this rift system, including the Torquay sub-basin and the adjacent Otway Ranges experienced major uplift and erosion related to compressional deformation that reactivated earlier extensional faults (Hill et al, 1995;Duddy, 2003). AFTA and VR data from wells and outcrops in the Otway Basin suggest that heat flow at ~95 Ma was approximately double present-day levels, and then declined rapidly, reaching present-day levels at ~80 Ma (Duddy, 2003).…”

Relative timing of CAMP, rifting, continental breakup, and basin inversion: Tectonic significance

“…Specifically, an extensional phase followed by a contractional phase creates positive inversion structures. Basin inversion occurs on active margins [e.g., de Graciansky et al, 1989;Letouzey, 1990;Ginger et al, 1993] and passive margins [e.g., Malcolm et al, 1991;Hill et al, 1995;Doré and Lundin, 1996;Vågnes et al, 1998;Withjack and Eisenstadt, 1999]. The above field and seismic studies, combined with experimental analysis [e.g., Buchanan and McClay , 1991;Mitra and Islam, 1994;Eisenstadt and Withjack, 1995;Keller and McClay, 1995;Brun and Nalpas, 1996], show that typical inversion structures include normal faults reactivated as reverse faults, newly formed reverse and thrust faults, monoclines, anticlines, and synclines (Figure 4).…”

“…In addition to the central North Atlantic passive margin, inversion in a passive-margin setting has occurred along the Norwegian margin of the North Atlantic Ocean [e.g., Doré and Lundin, 1996;Vågnes et al, 1998], the southeastern Australian margin [e.g., Hill et al, 1995], and the Northwest Shelf of Australia [e.g., Malcolm et al, 1991;Withjack and Eisenstadt, 1999] (Figure 4b). Like the central North Atlantic margin, the Norwegian margin is a volcanic passive margin [e.g., Hinz, 1981;Hinz et al, 1993], and parts of the Northwest Shelf of Australia are volcanic [Hopper et al, 1992].…”