Cretaceous–Tertiary inversion history of the Dampier Sub-basin, northwest Australia: Insights from quantitative basin modelling

2015

Geomorphology

A late Pleistocene (Marine Isotope Stage 5e) emergent marine sequence fringes the coastline of the Cape Region of coastal west central Australia and provides elevation and age control to characterize the locations and rates of crustal deformation. There is a systematic measurable change in relative paleo sea-level elevations across the Cape Region. High-precision leveling of modern and Pleistocene shoreline features indicates the minimum elevation range of MIS 5e shoreline features along the coast is 10.4 m. This compares with the 2.5 m elevation range for observed modern shoreline analogs. The lack of continuity of MIS 5e shoreline elevations along 300 km of coastline demonstrates continuing tectonic deformation along coastal anticlines in the Cape Region. Topographic expression of MIS 5e features indicates tectonic uplift consistent with late Neogene to Quaternary deformation on the Cape Cuvier and Cape Range anticlines. Post-MIS 5e tectonic uplift rates are up to 0.054 ± 0.035 mm/yr at fold axial locations. Estimated subsidence rates are − 0.013 ± 0.034 mm/yr on fold limbs. While the estimated vertical tectonic deformation is small and the rates are low, the geomorphological data also demonstrate tectonic activity, not stability.

Section: Geologic and Tectonic Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

2015

Geomorphology

“…Reactivation of Gondwana era rift-related structures is well documented in the Carnarvon basin (cf, Clark et al, 2012). The most recent structural reactivation is widely attributed to the reorganization of the northern Australian plate boundary that initiated during the Neogene (Densley et al, 2000;Kaiko and Tait, 2001;Audley-Charles, 2004, 2011Cathro and Karner, 2006;Keep et al, 2007;Hengesh et al, 2011) when the horizontal stress field in the Carnarvon basin realigned to east-west compression Reynolds, 2000, 2003;Hillis et al, 2008;Müller et al, 2012).…”

Section: Tectonicsmentioning

confidence: 99%

“…Old rift-related normal structures act as zones of weakness and are being preferentially exploited to accommodate crustal shortening (Sykes, 1978;Crone et al, 1997;Cathro and Karner, 2006;Revets et al, 2009;Keep et al, 2012;Müller et al, 2012;McPherson et al, 2013). Former rift-related extensional structures have undergone transform and contractional reactivation leading to structural inversion of basin sequences (Densley et al, 2000;King et al, 2010).…”

Section: Tectonicsmentioning

confidence: 99%

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Geomorphological evidence of neotectonic deformation in the Carnarvon Basin, Western Australia

2015

Geomorphology

This study examines channel-scale morphodynamics of ephemeral streams in the onshore Carnarvon basin in arid west-central Western Australia. The rivers in this region have low gradients, the landscape has low relief, and the rates of climatically and tectonically driven geomorphic processes also are low. As a result, the rivers in the Carnarvon alluvial plain are highly sensitive to minor perturbations in base level, channel slope, and fluvial energy. We use channel planform adjustments, stream gradient changes, and floodplain profiles across multiple ephemeral streams within a variety of catchments and flow regimes to determine if tectonically driven land level changes are affecting channel form and fluvial processes. Growth of individual fold segments is shown to have altered stream and floodplain gradients and triggered repeated avulsions at structurally controlled nodes. Aligned perturbations in channel form across multiple channel-fold intersections provide systematic geomorphic evidence for the location and orientation of neotectonic structures in the region. These features occur as a belt of low relief anticlines in the Carnarvon alluvial plain.

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

2016

Tectonics

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.