Episodic Precambrian subduction

Abstract

Abstract: The Precambrian geological record shows peak of activity at 1.1, 1.9-2.1, 2.7 and 3.5 Ga, often associated with massive crustal production, orogenesis and supercontinent cycles. It has been suggested that these bursts of tectonic activity are due to mantle avalanche events, where accumulating subducted slabs periodically penetrate the 670 km discontinuity, and subsequent upwelling counterflow and plume activity results in massive volcanism. Here we present paleomagnetic evidence for periods of rapid plate motions coinciding with the observed peaks in crustal age distribution. We present a new model for plate-driven episodic tectonics in the Precambrian, where higher mantle temperatures result in lower lithospheric stresses, causing rapid pulses of subduction interspersed with periods of relative quiescence. Plate-driven episodicity will naturally arise for hotter mantle temperatures of the early Earth and can explain rapid pulses of plate motion and crustal production without the need to invoke mantle avalanche events.