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Plate Tectonic Evolution of Circum-Antarctic Passive Margins

Christopher R. Scotese, Lawrence A. Lawver, John G. Sclater, Catherine L. Mayes, Ian Norton, Jean-Yves Royer

Passive margins that formed during the Late Jurassic and Cretaceous account for approximately 80% of the 15,000-km circumference of Antarctica. There are no passive margins younger than Late Cretaceous. Approximately 28% of these margins are Late Jurassic in age, 24% are Early Cretaceous in age, and the remaining 48% formed during the Late Cretaceous. The tectonic style of the rifting events that formed these margins varies considerably along the perimeter of Antarctica. In several areas the initiation of sea-floor spreading was preceded by a long period of extension and predrift stretching (Wilkes Land). Along other portions of the margin, rifting proceeded rapidly with little evidence for a lengthy phase of pre-drift extension (Queen Maud Land). Though extension is the ominant tectonic style, there is evidence for large-scale strike-slip movement associated with the early phases of continental breakup along the coasts of Crown Princess Martha Land and Victoria Land. Except for a short segment of the margin between the West Antarctic peninsula and Marie Byrdland, the Antarctic passive margins have not been affected by subsequent subduction-related compressive deformation.

This presentation will review the plate tectonic evolution of the Circum-Antarctic passive margins during five time intervals: Early Jurassic, Late Jurassic, Early Cretaceous, mid-Cretaceous, and latest Cretaceous. A map illustrating the relative amounts of extension along the margin of Antarctica will be presented, and a computer animation illustrating the breakup of Gondwana from an Antarctic perspective will be shown.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.