Volcanic rifted margins

Abstract

Active rifting (plume-driven) models are the traditional explanation for the formation of volcanic rifted margins with significant surface uplift occurring prior to flood volcanism and break-up extension. However, recent research on volcanic rifted margins indicates that their evolution is more complex than that defined by earlier models, and several hybrid models have been proposed. At the Penrose 2000 Volcanic Rifted Margin Conference held at Royal Holloway, University of London, discussion centered on the margins of the north, central, and south Atlantic Ocean, the western and eastern coasts of Australia, the southern Red Sea, the west coast of India and its conjugate margins in Madagascar and the Seychelles. The characteristic features of volcanic rifted margins were summarized and it was agreed that formation of a volcanic rifted margin required complete rifting of a continent to form an ocean above an upper mantle with a temperature 100–200 °C above "normal" asthenosphere. This should be contrasted with rifting without additional thermal perturbation which leads to nonvolcanic rifted margins (e.g., Newfoundland, Iberia) and thermal perturbations in the absence of rifting which lead to formation of intraplate large igneous provinces in ocean basins (e.g., Ontong-Java oceanic plateau) and on continents (e.g., Siberian flood basalts).