Solitary waves forming pulsating thermal plumes and their implications for multiple eruption events in large igneous provinces

Abstract

In Earth's mantle, gravity instabilities initiated by density inversion lead to upwelling of hot materials as plumes. This study focuses upon the ascent dynamics of plumes to provide an explanation of the periodic multiple eruption events in large igneous provinces (LIP) and hotspots. We demonstrate that depending on physical conditions, plumes can either ascend in a continuous process with a single, large head trailing into a long slender tail, or alternatively, they ascend in a pulsating fashion producing multiple inaxis heads. Based on the Volume of Fluid (VOF) method, we performed computational fluid dynamics (CFD) simulations to constrain the thermo-mechanical conditions that decide the continuous versus pulsating dynamics. The simulations suggest the density (ρ*) and the viscosity (R) ratios of the ambient to the plume and the influx rates (Re) are the prime factors in controlling the ascent dynamics. The simulations could also predict thermal events near the surface causing eruption periodically as pulses. The pulsating plume model explains the multiple eruption events in different LIPs and our simulation results predict that variation in the temperature of the source layer can cause a range of timescale for this periodicity.