Subduction tectonics vs. Plume tectonics—Discussion on driving forces for plate motion

Abstract

Plate tectonics describes the horizontal motions of lithospheric plates, the Earth’s outer shell, and interactions among them across the Earth’s surface. Since the establishment of the theory of plate tectonics about half a century ago, considerable debates have remained regarding the driving forces for plate motion. The early “Bottom up” view, i.e., the convecting mantle-driven mechanism, states that mantle plumes originating from the core-mantle boundary act at the base of plates, accelerating continental breakup and driving plate motion. Toward the present, however, the “Top down” idea is more widely accepted, according to which the negative buoyancy of oceanic plates is the dominant driving force for plate motion, and the subducting slabs control surface tectonics and mantle convection. In this regard, plate tectonics is also known as subduction tectonics. “Top down” tectonics has received wide supports from numerous geological and geophysical observations. On the other hand, recent studies indicate that the acceleration/deceleration of individual plates over the million-year timescale may reflect the effects of mantle plumes. It is also suggested that surface uplift and subsidence within stable cratonic areas are correlated with plume-related magmatic activities over the hundred-million-year timescale. On the global scale, the cyclical supercontinent assembly and breakup seem to be coupled with superplume activities during the past two billion years. These correlations over various spatial and temporal scales indicate the close relationship and intensive interactions between plate tectonics and plume tectonics throughout the history of the Earth and the considerable influence of plumes on plate motion. Indeed, we can acquire a comprehensive understanding of the driving forces for plate motion and operation mechanism of the Earth’s dynamic system only through joint analyses and integrated studies on plate tectonics and plume tectonics.