Seismic Imaging of Thickened Lithosphere Resulting From Plume Pulsing Beneath Iceland

Catherine Rychert (1) , Nicholas Harmon (1) , John Armitage (2)

1 NOC - National Oceanography Centre [Southampton]
2 IPGP - Institut de Physique du Globe de Paris

Ocean plates conductively cool and subside with seafloor age. Plate thickening with age is also predicted, and hot spots may cause thinning. However, both are debated and depend on the way the plate is defined. Determining the thickness of the plates along with the process that governs it has proven challenging. We use S-to-P (Sp) receiver functions to image a strong, persistent LAB beneath Iceland where the mid-Atlantic Ridge interacts with a plume with hypothesized pulsating thermal anomaly. The plate is thickest, up to 8466 km, beneath lithosphere formed during times of hypothesized hotter plume temperatures and as thin as 6166 km beneath regions formed during colder intervals. We performed geodynamic modeling to show that these plate thicknesses are inconsistent with a thermal lithosphere. Instead, periods of increased plume temperatures likely increased the melting depth, causing deeper depletion and dehydration, and creating a thicker plate. This suggests plate thickness is dictated by the conditions of plate formation.

Keywords: RAYLEIGH-WAVE TOMOGRAPHY; UPPER CRUSTAL STRUCTURE; V-SHAPED RIDGES; UPPER-MANTLE; ASTHENOSPHERE BOUNDARY; HAWAIIAN PLUME; RECEIVER FUNCTIONS; REYKJANES RIDGE; MELT EXTRACTION; OLIVINE

Domains: Geophysics [physics.geo-ph]

Catherine Rychert, Nicholas Harmon, John Armitage. Seismic Imaging of Thickened Lithosphere Resulting From Plume Pulsing Beneath Iceland. Geochemistry, Geophysics, Geosystems, 2018, 19 (6), pp.1789-1799. ⟨10.1029/2018GC007501⟩. ⟨insu-02919988⟩