The separation of Australia from other continents

J. J. Veevers*, M. W. McElhinny

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    52 Citations (Scopus)

    Abstract

    Palaeomagnetism provides the chief constraints on models of the separation of Australia from other continents. Palaeomagnetic studies suggest that the various cratons that comprise the main Australian platform have maintained the same relative position from 1800 m.y. to 750 m.y. ago, and, in greater detail, that the Australian platform, excluding the Tasman Fold Belt, has maintained its physical integrity from 750 m.y. to 450 m.y. ago. Furthermore, palaeomagnetic studies in Australia and the other Gondwanaland fragments indicate that Gondwanaland must have existed at least 750 m.y. ago until its disintegration about 150 m.y. ago. Geological studies suggest that the first clearly recorded separation of other continents from Australia occurred at the end of the Precambrian with the inception of the eastern (Pacific) and northwestern (Tethyan) margins by plate divergence between Australia and unknown continents. Thereafter, the active Pacific margin migrated eastward by the accretion of island-arc material, and the passive Tethyan margin, after its complete development in the Early Ordovician, was static until the Mesozoic. In contrast with this early phase of continental separation, the modern (Mesozoic-Palaeocene) separation of Australia from its Gondwanaland neighbours is traceable by information preserved on the existing ocean floor as well as on the formerly contiguous continents. In detail, the only obscurity remains on the Pacific margin due to a complex pattern of divergence. Greater India separated from Antarctica/Australia early in the Cretaceous (130 m.y. ago) and Antarctica separated from Australia at the end of the Palaeocene (53 m.y. ago). Each of these events was preceded by a period, 170 m.y. long between India and Australia and 110 m.y. long between Antarctica and Australia, of uplift, erosion, and thick terrigenous deposition in rift valleys. It is the subsequent deposition along the western and southern continental margins of fine marine sediments on porous coarse non-marine rift valley sediments that has led to the accumulation of Australia's main known oil and gas resources. The Lord Howe Rise and the New Zealand Plateau separated from Australia in the Late Cretaceous and Palaeocene, as denoted by the generation of the floor of the Tasman Sea, and southeast Papua separated from Australia in the early Eocene, as denoted by the generation of the floor of the Coral Sea. In separating from Antarctica, Australia moved northward and, as shown by palaeomagnetic studies, collided with Southeast Asia no earlier than the Late Cenozoic.

    Original languageEnglish
    Pages (from-to)139-143
    Number of pages5
    JournalEarth Science Reviews
    Volume12
    Issue number2-3
    DOIs
    Publication statusPublished - Jul 1976

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