Kinematic reconstruction of the Jurassic intraplate rift deformation in the Northern Carnarvon Basin, Australia

Abstract

Intraplate rift basins, like the inboard sub-basins of the Northern Carnarvon Basin (NCB), host rich energy resources, but their complex geological histories complicate exploration efforts. The paleo-deformation that formed these intraplate rifts also controlled their resource systems distribution. Hence, understanding their complex kinematic and tectonostratigraphic histories can optimise exploration and targeting. However, without forming oceanic seafloor, these regions lack adjacent magnetic seafloor isochrons to constrain paleo-positions of rift margins, rendering kinematic reconstruction nearly impossible. We present a method that constrains the spatiotemporal paleo-distribution of intraplate rift-related deformation and precisely locates paleo-positions of rift margins using time-dependent backstripped subsidence rasters. This method correlates areas with high subsidence rates with rifted regions within extension settings, and we apply it to reconstruct the kinematic evolution of the NCB sub-basin rift.Reconstruction results indicate that the Late Triassic – Early Jurassic extension initiated rifting in the nearshore parts of the NCB, creating Exmouth and Barrow sub-basin grabens at 8 mm/yr maximum rift widening rates. Rifting shifted northeastwards into the Dampier and Beagle regions from Mid Jurassic to Early Cretaceous. Rifting rates in the nearshore regions slowed at ∼155 Ma, coinciding with the Argoland – Australia separation and seafloor spreading within the outboard Argo region. The rates increased again at ∼145 Ma during the Tithonian extension and then decreased significantly at ∼120 Ma during the seafloor spreading in the Cuvier and Gascoyne regions. The temporal correlation between Gondwana dispersal events and the nearshore sub-basin rift evolution suggests that the sub-basins were part of a broader deformation zone across the margin. However, strain localised and triggered breakup and seafloor spreading within the outboard Argo, Gascoyne, and Cuvier regions. Such breakups released extension forces and caused rift cessation in the nearshore NCB sub-basins.