Plate tectonic chain reaction revealed by noise in the Cretaceous quiet zone

Abstract

Global reorganizations of tectonic plates may be caused by a trigger such as a continental collision or a rising mantle plume. However, whether and how such a trigger propagates through a plate circuit remains unclear. Here we use a plate kinematic model to quantify relative motions between the African and Eurasian plates following a plume-induced plate motion change that triggered formation of a new subduction zone within the Neotethys Ocean at 105 Ma. We constrain the plate kinematic model by geomagnetic intensity variations recorded in Atlantic quiet zone crust that formed during the Cretaceous Normal Superchron (126–83 Ma), during which magnetic reversals were absent. We find that convergence rate changes between Africa and Eurasia are well explained by the initiation and arrest of the plume-induced subduction zone. Our plate kinematic model also reveals that the plate acceleration that followed upon subduction initiation changed the Africa–Eurasia convergence direction, which in turn was accommodated by subsequent subduction initiation about 85 Ma in the Alpine region that then triggered a cascade of regional tectonic events. This plate tectonic chain reaction illustrates how changes in plate motion, underpinned by mantle dynamics, may self-perpetuate through a plate circuit.