Mantle Plume – Spreading Ridge Interaction: A Comparative Study of the Red Sea and Reykjanes Ridges

Abstract

<p>As a young, mid ocean ridge, the Red Sea is a unique natural laboratory for studying the processes that drive continental rifting and breakup. The role of hot spots, frequently attributed to mantle plumes, in triggering or driving breakup and their impact on crustal structure and topography is not well understood. We have found that the Red Sea ridge bears a resemblance to the Reykjanes ridge in terms of bathymetry, morphology, geophysical properties, basalt chemistry, and modelled melting temperature and pressure of primary basalts. The results of modelling basalt melting temperature call into question the role of mantle temperature on generating excess melt beneath the Red Sea and Reykjanes ridges. Within 300 kilometers of a hotspot center, determined by seismic tomography, mantle excess temperatures are as high as 300 degrees relative to an ambient mantle temperature of about 1300 C. Outside of this radius excess temperatures are not significant (less than 50 C), and unlikely to cause significant melting anomalies. It is likely that the southern Red Sea and northern Reykjanes ridge are directly affected by hot, buoyant upwelling from the Afar and Iceland mantle plumes, and the central Red Sea and southern Reykjanes ridge may be affected by dynamic pressure related to actively upwelling mantle around the mantle plumes.</p>