Publication Name: Eastern Australian Basins Symposium III (EABS 2008)
Authors: K.L. Hoffmann, N.F. Exon, P.G. Quilty and C.S. Findlay
Date Published: September 2008
Number of Pages: 8
Abstract:
The east coast of Australia was dominated by prolonged periods of subduction and accretion during the Palaeozoic–Mesozoic (Scheibner & Veevers 2000). Widespread rifting and seafloor spreading replaced the compressional regime from around 120 Ma (Early Cretaceous) off southeast Australia (Crawford et al. 2003). As recorded by the magnetic anomalies in the newly formed oceanic crust, spreading commenced in the south and migrated progressively northwards, carving off two large ribbon-like microcontinents (Hayes & Ringis 1973; Shaw 1990; Langford et al. 1995; Gaina et al. 1998; Mueller et al. 2000; Brown et al. 2003; Crawford et al. 2003). These northwest-oriented features are known as the New Caledonia–Norfolk Ridge and the Lord Howe Rise and extend along strike for a distance of approximately 2,000 km. A phase of Cretaceous extension and associated volcanism dissected and weakened the Queensland margin, producing intracontinental rift basins and heralding the imminent continental drifting (Willcox 1981; Symonds et al. 1996; Exon et al. 2005). Seismic interpretation of synrift packages along the northern Kenn Plateau by Exon et al. (2005, 2006b) identified 2.5–4.0 km thick sequences of presumed Late Cretaceous–Early Eocene age. Seafloor spreading reached the northern Tasman, Cato, and Coral Sea basins around 65 Ma, commencing the break-up of the northeast Australian margin (Figure 1; Exon et al. 2005). We support the idea by Shaw (1990), Hill (1994), and Exon et al. (2005) that the Capricorn Basin represents a failed arm (aulacogen) of a triple junction at the northern end of the Tasman Basin. However, terrestrial and marine sediments continued to accumulate in the Capricorn depocentre until the Holocene (Ericson 1976; Day et al. 1983).