The 1800–1100 Ma tectonic evolution of Australia

This paper presents a plate tectonic model for the evolution of the Australian continent between ca. 1800 and 1100 Ma. Between ca. 1800 and 1600 Ma episodic orogenesis occurred along the southern margin of the continent above a north-dipping subduction system. During this interval multiple orogenic events occurred. The West Australian Craton collided with the North Australian Craton (ca. 1790–1770 Ma), the Archaean nucleus of the Gawler Craton amalgamated with the North Australian Craton (ca. 1740–1690 Ma), and numerous smaller terranes accreted along the western Gawler Craton and the southern Arunta Inlier (ca. 1690–1640 Ma). The pattern of accretion suggests southward migration of the plate margin, which occurred due to a combination of slab rollback and back stepping of a subduction system behind the accreted continental blocks. Coeval with subduction a series of continental back-arc basins formed in the interior of the North Australian Craton and parts of the South Australian Craton, which were attached to the North Australian Craton prior to 1500 Ma. Extension of the North Australian Craton led to the opening of an oceanic basin along the eastern margin of the continent at ca. 1660 Ma. Continuing divergence was accommodated by oceanic spreading whereas the continental basins thermally subsided resulting in the development of sag-phase basins throughout the North Australian Craton. This oceanic basin was subsequently consumed during convergence, which ultimately led to development of a ca. 1600–1500 Ma orogenic belt along the eastern margin of Proterozoic Australia. Between ca. 1470 and 1100 Ma, the South Australian Craton, consisting of the Curnamona Province and the Gawler Craton rifted from the North Australian Craton and was re-attached in its present configuration during episodic ca. 1330–1100 Ma orogenesis, which is preserved in the Albany-Fraser Belt and the Musgrave Block.