Transcurrent reactivation of Australia's western passive margin: An example of intraplate deformation from the central Indo‐Australian plate

Abstract

Australia's northwestern passive margin intersects the eastern termination of the Java trench segment of the Sunda arc subduction zone and the western termination of Timor trough along the Banda arc tectonic collision zone. Differential relative motion between the Sunda arc subduction zone and the Banda arc collision zone has reactivated the former rifted margin of northwestern Australia evidenced by Pliocene to Quaternary age deformation along a 1400 km long offshore fault system. The fault system has higher rates of seismicity than the adjacent nonextended crustal terranes, has produced the largest historical earthquake in Australia (1941 M L 7.3 Meeberrie event), and is dominated by focal mechanism solutions consistent with dextral motion along northeast trending fault planes. The faults crosscut late Miocene unconformities that are eroded across middle Miocene inversion structures suggesting multiple phases of Neogene and younger fault reactivation. Onset of deformation is consistent with the timing of the collision of the Scott Plateau part of the passive continental margin with the former Banda trench between 3.0 Ma and present. The range of estimated maximum horizontal slip rates across the zone is~1.4 to 2.6 mm yr À1 , at the threshold of geodetically detectable motion, yet significant with respect to an intraplate tectonic setting. The folding and faulting along this part of the continental margin provides an example of intraplate deformation resulting from kinematic transitions along a distant plate boundary and demonstrates the presence of a youthful evolving intraplate fault system within the Indo-Australian plate.

Quantitative analysis of a footwall‐scarp degradation complex and syn‐rift stratigraphic architecture, Exmouth Plateau, NW Shelf, offshore Australia

“…This activity resulted in transpressional growth of pre‐existing normal faults (Bradshaw et al, 1988; Tindale et al, 1998). Subsequently, during the Neogene, collision between the Australian plate and the Java‐Banda arc (SE Asia) caused inversion and reactivation of faults across the northern Carnarvon Basin (Deng & McClay, 2019; Hengesh & Whitney, 2016; Keep, Powell, & Baillie, 1998; Figure 3).…”

Quantitative analysis of a footwall-scarp degradation complex and syn-rift stratigraphic architecture, Exmouth Plateau, NW Shelf, offshore Australia

“…This activity resulted in transpressional growth of pre-existing normal faults (Bradshaw et al, 1988;Tindale et al, 1998). Subsequently, during the Neogene, collision between the Australian plate and the Java-Banda arc (SE Asia) caused inversion and reactivation of faults across the northern Carnarvon Basin (Deng & McClay, 2019;Hengesh & Whitney, 2016;Keep, Powell, & Baillie, 1998;Figure 3).…”

Timor Collision Front Segmentation Reveals Potential for Great Earthquakes in the Western Outer Banda Arc, Eastern Indonesia

“…To constrain the nature and distribution of the deformation along this modern arc-continent collision example, the Outer Banda arc, some studies have been performed along three main transects located between Sumba and Savu islands (120-121°30′E) (e.g., Breen et al, 1986;Masson et al, 1991;Shulgin et al, 2009), and offshore West and East Timor Island (123-124°30′E and 127°30-128′E, respectively) (e.g., Karig et al, 1987;Charlton et al, 1991;Hugues et al, 1996) (Figure 1). Although varying in style and intensity, the consistent predominant modes of deformation along these transects appear to lie in: 1) frontal accretion processes at the foot of the huge Timor accretionary wedge, where recent trough fill, slope sediments, and/or part of the Australian continental-margin strata are folded and thrusted above a décollement (e.g., Breen et al, 1986;Karig et al, 1987;Charlton et al, 1991;Masson et al, 1991;Shulgin et al, 2009;Baillie and Milne, 2014), and 2) sets of deeply rooted normal faults dissecting the Ashmore and Sahul platform sedimentary sequences (e.g., Keep et al, 2002;Barber et al, 2003), locally active in the Quaternary (Hengesh and Whitney, 2016). Although these studies provide some local information along these transects, a detailed characterization of active deformation along the entire Timor Trough is lacking, which is essential for earthquakes and tsunami hazard assessment.…”