The role of subduction in the formation of Pangean oceanic large igneous provinces

Abstract

Large igneous provinces (LIPs) have been linked to both surface and deep mantle processes related to supercontinent formation. During the formation, tenure, and breakup of Pangea, the most recent supercontinent, there is a noted contemporaneous increase in the number of emplacement events of both continental and oceanic LIPs. There is currently no clear consensus on the origin of LIPs, but the most widely recognized hypothesis relates their formation to crustal emplacement of hot plume material originating in the deep mantle. The interaction of subducted slabs with the lowermost mantle thermal boundary and subsequent return-flow is a key control on plume generation. This mechanism has been explored for LIPs below the interior of a supercontinent (e.g., continental LIPs). However, a number of LIPs related to Pangea formed at the supercontinent’s exterior (e.g., Ontong Java Plateau in the Pacific Ocean), with no consensus on their formation mechanism. In this research, we consider the dynamics of global-scale supercontinent processes resultant from numerical models of mantle convection, and analyse whether circum-supercontinent subduction could generate both interior (continental) and exterior (oceanic) deep-mantle plumes. Our 2-D and 3-D numerical models show that subduction related to the supercontinent cycle can reproduce the location and timing of the Ontong Java Plateau, Caribbean LIP, and potentially the Shatsky Rise, when relating these LIPs to a deep mantle exterior plume. The findings here highlight the importance of taking into consideration mantle dynamics in every stage of the supercontinent cycle.