Jumps of Subduction Zones, Subduction Reversal, and Closing of Back Arc Basins

Abstract

In Section 4.11 we discussed the mechanisms for increasing compression of the lithosphere in a subduction zone. These mechanisms are; subduction of young lithosphere, an increase in subduction rate, subduction of different asperities (seamounts, ridges) and plateaux. The most intensive compression occurs during subduction of the continental margin, that is during collision of the subduction zone with a continent. High compressive stresses can produce failure of the lithosphere in a new place resulting in the initiation of a new subduction zone at this place. Such a phenomenon is recognised in many fold belts[Dewey and Bird1970;Kovalev1985;Koltypin1991] and can be designated as a jump of subduction zone (similar to the jumps of spreading axis in fast[Shemenda and Grocholsky1991], slow[Shemenda and Grocholsky1994] ridges and the jumps of continental rifts[Malkin and Shemenda1991]). With jumps of subduction zones are related such processes as reorganization of the plate boundaries, evolution of the inner trench slopes, reversal subduction[Dickinson and Seely1979;Mitchell1984], as well as closing of back arc basins. This chapter is devoted to these problems.