Rifted Margins: Building Blocks of Later Collision

Abstract

AbstractRifted margins develop by the splitting apart of continents and form the trailing edges of ocean basins, to be incorporated into collision zones when those basins eventually close. Magma-poor margins are dominated by tectonic processes, including crustal extension and thinning, mantle serpentinization and the unroofing of broad expanses of lithospheric mantle. Magma rich margins may follow a similar history until breakup, when magmatic processes dominate, producing thick piles of basaltic/gabbroic rocks. The presence or absence of thick mafic igneous sequences on the one hand and mantle serpentinites on the other may play a crucial role in the way rifted margins respond to convergence: magma-poor rifted margins are likely to form the upper plate to incipient subduction and thus be incorporated into orogens such as the Ligurian margins in the Alps and the Dalradian margin in the Grampian. The paucity of clear examples of magma rich margins incorporated into orogens implies that these may be more likely to be successfully subducted as the thick mafic sequences are converted to eclogites.KeywordsLower CrustDetachment FaultRift MarginContinental BreakupRockall TroughThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.