Slab avalanche-induced tectonics in self-consistent dynamic models

Abstract

Subducted slabs often temporarily stagnate within the transition zone and then periodically penetrate into the lower mantle in the form of a slab avalanche. We investigate the influence of such slab avalanches on tectonics with dynamically consistent numerical models. We suggest that slab avalanches can induce substantial changes in surface tectonics, including synchronous broad-scale basin inversion and dynamic subsidence in regions above the avalanched slab, and reducing (or even reversing) trench retreat. However, basins distal from the trench and avalanched slab continue extension following avalanche onset. We suggest that a slab avalanche event beneath the Sundaland continental promontory began in the early Miocene to trigger a wide range of tectonic responses within Southeast Asia, including (1) a reduction of the Sunda-Java Trench retreat velocity (that may have transitioned to advance regionally) since the early Miocene; (2) synchronous basin compression and subsidence within southern Sundaland since the early Miocene; and (3) continuous basin extension, with some developing to ultra-deep rifted basins, in the northern part of Sundaland. We also discuss the implication of the slab avalanche model in the context of the history of the Taranaki Basin offshore New Zealand.