Timing of Seafloor Spreading Cessation at the Macquarie Ridge Complex (SW Pacific) and Implications for Upper Mantle Heterogeneity

Abstract

Mid-ocean ridges are Earth's most important producers of igneous rocks and contribute ∼75% of Earth's present-day volcanism (Crisp, 1984). While much is known about the production of mid-ocean ridge basalts (MORBs) by mantle upwelling and decompression melting at active mid-ocean ridges, the magmatic processes during mid-ocean ridges' slowdown and eventual cessation in response to plate reorganization are less well understood. Despite, the wide distribution of extinct mid-ocean ridges on Earth (see review of Ma-cLeod et al., 2017), much of current knowledge of such processes comes from studies of the fossil Phoenix Ridge off the Antarctic Peninsula (