Publication Name: Eastern Australian Basins Symposium 2001
Authors: M.S. Norvick, M.A. Smith and M.R. Power
Date Published: November 2001
Number of Pages: 32
Reference Type: Magazine Article
Abstract:
Stratigraphic changes in eastern Australasia illustrate north to south variations in tectonic evolution. Common themes include TriassicJurassic subduction from the Papuan Fold Belt to New Zealand. Also, Late Barremian-Albian volcanogenic sedimentation caused by back-arc volcanism occurred along the whole margin. Local developments include Lower Cretaceous rift basins in the Bass Strait area, related to north-south extension between Australia and Antarctica. Turonian-Santonian rift basins, associated with east-west Tasman Sea opening, occur from New Zealand to the Lord Howe Rise but not in PNG. Rift basins under the Queensland Plateau may be slightly younger.Tasman Sea seafloor spreading started in the south in the mid-Santonian (c. 85 Ma) and tore irregularly northwards until it stopped in the Early Eocene (c. 54 Ma). A later spreading event opened the Coral Sea starting in the Paleocene (c. 62 Ma), which was associated with a widespread disconformity in PNG, but not in southern basins.
Subduction prisms began approaching northeastern Australasia in the Early Eocene. Collision emplaced ultra-mafic belts in the Papuan peninsula, New Guinea highlands and New Caledonia.
The Antarctic and New Zealand margins evolved by Late Cretaceous-Tertiary rifting and back-arc spreading over slightly different time intervals than further north. Mid-Cretaceous rift basins began forming in the Ross Sea and Great South Basin, changing to post-rift sags by the Campanian (c. 80 Ma). Pakawau rift basins were initiated in
western New Zealand in the Campanian. A distinct set of Challenger rifts developed separately in the Ross Sea and western New Zealand in the Eocene. Eventually extension led to opening of the Emerald oceanic basin in the later Tertiary.
Neogene to Recent history is characterised by divergence of local stratigraphy and tectonics, reflecting increasing complication of the eastern Australasian margin by back-arc spreading, arc collision and compression in the north, and transpressional faulting in New Zealand.