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Interactions between continental breakup dynamics and large‐scale delta system evolution: Insights from the Cretaceous Ceduna delta system, Bight Basin, Southern Australian margin
Author(s) -
Espurt Nicolas,
Callot JeanPaul,
Totterdell Jennifer,
Struckmeyer Heike,
Vially Roland
Publication year - 2009
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2009tc002447
Subject(s) - geology , paleontology , tectonics , denudation , cretaceous , structural basin , lithosphere , geomorphology , delta , seismology , continental margin , aerospace engineering , engineering
The interpretation of two regional seismic reflection profiles and the construction of a balanced cross section through the southern Australian margin (Bight Basin) are designed to analyze the influence of the Australia‐Antarctica continental breakup process on the kinematic evolution of the Cretaceous Ceduna delta system. The data show that the structural architecture of this delta system consists of two stacked delta systems. The lower White Pointer delta system (Late Albian‐Santonian) is an unstable tectonic wedge, regionally detached seaward above Late Albian ductile shales. Sequential restoration suggests that the overall gravitational sliding behavior of the White Pointer delta wedge (∼45 km of seaward extension, i.e., ∼27%) is partially balanced by the tectonic denudation of the subcontinental mantle. We are able to estimate the horizontal stretching rate of the mantle exhumation between ∼2 and 5 km Ma −1 . The associated uplift of the distal part of the margin and associated flexural subsidence in the proximal part of the basin are partially responsible for the decrease of the gravitational sliding of the White Pointer delta system. Lithospheric failure occurs at ∼84 Ma through the rapid exhumation of the mantle. The upper Hammerhead delta system (Late Santonian‐Maastrichtian) forms a stable tectonic wedge developed during initial, slow seafloor spreading and sag basin evolution of the Australian side margin. Lateral variation of basin slope (related to the geometry of the underlying White Pointer delta wedge) is associated with distal raft tectonic structures sustained by high sedimentation rates. Finally, we propose a conceptual low‐angle detachment fault model for the evolution of the Australian‐Antarctic conjugate margins, in which the Antarctic margin corresponds to the upper plate and the Australian margin to the lower plate.