Laura M. Wallace, Robert McCaffrey, John Beavan, Susan Ellis; Rapid microplate rotations and backarc rifting at the transition between collision and subduction. Geology 2005; 33 (11): 857-860. doi: 10.1130/G21834.1
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Using global positioning system velocities from convergent plate boundaries in Papua New Guinea, New Zealand, Tonga, Vanuatu, and the Marianas, we note a spatial correlation between rapid tectonic block rotations and the transition from subduction to collision. We present a mechanism for the block rotations, in which the change from collision of a buoyant indentor to normal subduction exerts a torque on the upper-plate microplate. This work improves our understanding of the causes of rapid vertical axis rotations, often observed in paleomagnetic studies. We also show how collision-induced rotations may lead to backarc rifting.