Subduction-Related Volcanic Activity as a Proxy for Global Subduction Flux Over the Past Billion Years, and Its Correlation With Geomagnetic Superchrons

Abstract

We investigate the frequency of subduction-related volcanic events over the past billion years. Our analysis reveals distinct peaks and troughs interpreted as significant fluctuations in global subduction flux. This approach has the advantage of being independent of paleogeographic reconstructions. However, it does not provide information on the spatial distribution of thermal heterogeneities at the core-mantle boundary. This likely explains why the long-term evolution of global subduction flux does not correlate in any simple way with the frequency of geomagnetic polarity reversals throughout the Phanerozoic. As an additional parameter, we suggest focusing on how variations in the Earth's inertia, due to changing subduction configurations over time, influence the thermal conditions at the core-mantle boundary and, consequently, the magnetic reversal frequency.