Phys.org September 28, 2024
The Pacific large low-shear-velocity province (LLSVP) hosts multiple internal anomalies, including a notable gap between the central and eastern Pacific. The cause of the structural gap remains unconstrained. An international team of researchers (USA – University of Maryland, Canada) used a dense set of SS precursors (seismic waves) identify an anomalously thick mantle transition zone east of the East Pacific Rise directly above this structural gap. The area of the thickened transition zone exhibited faster-than-average velocities according to recent tomographic images, suggesting perturbed post olivine phase boundaries shifting in response to lowered temperatures. The researchers attributed this observation to episodes of Mesozoic-aged (250 to 120 million years ago) intraoceanic subduction beneath the present-day Nazca Plate. The eastern portion of the Pacific LLSVP was separated by downwelling because of this ancient oceanic slab. According to the researchers their discovery provides a unique perspective on linking deep Earth structures with surface subduction… read more. Open Access TECHNICAL ARTICLEÂ
Topography and tectonics of the SEPR and its surrounding oceans. Credit: Science Advances, 27 Sep 2024, Vol 10, Issue 39