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Regional Syntheses |
British Antarctic Survey, High Cross, Madingley Rd, Cambridge CB3 0ET, UK
(e-mail: a.vaughan{at}bas.ac.uk)
A review of evidence for deformation and terrane accretion on the Late Triassic-Early Jurassic margins of Pangaea and the mid-Cretaceous margins of the palaeo-Pacific ocean shows that deformation was global and synchronous with probable superplume events. Late Triassic-Early Jurassic deformation appears to be concentrated in the period 202–197 Ma and was coeval with eruption of the Central Atlantic Magmatic Province, onset of Pangaea break-up, a period of extended normal magnetic polarity and a major mass extinction event, all possible expressions of a superplume event. Mid-Cretaceous deformation occurred in two brief periods, the first from approximately 116 Ma to 110 Ma in the west palaeo-Pacific and the second from roughly 105 Ma to 99 Ma in the east palaeo-Pacific, with both events possibly represented in northeast Siberia. This deformation was coeval with eruption of major oceanic plateaux, core-complex formation and rifting of New Zealand from Gondwana, the Cretaceous normal polarity epoch, and a major radiation of flowering plants and several animal groups, all linked with the mid-Cretaceous superplume event. A simple unifying mechanism is presented suggesting that large continental or oceanic plates, when impacted by a superplume, tend to break-up/reorganize, associated with gravitational spreading away from a broad, thermally generated topographic high and with a resulting short-lived pulse of plate-marginal deformation and terrane accretion.
