Collaborative Research: Quantifying melt in the mantle and controls on lithosphere-asthenosphere dynamics and intraplate magmatism: a joint seismic and EM survey of the Cocos plate

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

The Earth’s surface is covered by tectonic plates that slowly move over a weaker layer called the asthenosphere. This project seeks to understand how much of the weakness in this layer is from melt droplets. The study area is the Cocos Plate in the eastern Pacific Ocean. A field project will use seafloor instruments to measure the seismic and electric structure of the mantle. The new observations will be used to measure the amount of melt in the asthenosphere and the relationship with abundant volcanism in the region. The results are important for better understanding plate tectonics, volcanism, and earthquakes, contributing to broader knowledge of dynamic Earth systems and natural hazards. The project will support the research activities of graduate and undergraduate students and international collaborations. This project will utilize passive-source seismic and magnetotelluric imaging to quantify the seismic velocity and electrical resistivity structure of the Cocos Plate lithosphere and asthenosphere. A co-located array of ocean-bottom seismic and electromagnetic receivers will be deployed over a section of the Cocos Plate on both sides of the Nicaragua Fracture Zone. The seafloor in the survey area shows abundant evidence of past intraplate magmatism, including elevated seafloor bathymetry, numerous seamounts significantly younger than the plate age, and prominent volcanic sills within the sediment column. Observations from this study will provide new insights on the dominant controls on asthenosphere rheology and the mechanisms that produce intraplate magmatism by addressing the following key questions: (1) What is the spatial and depth extent of the high-melt region? (2) Are seismic observations consistent with magnetotelluric results, can they be calibrated to each other, and what does it imply for the weakening mechanisms in the asthenosphere? (3) Does the mantle fabric change across the fracture zone and does the implied flow field suggest a plume influence? This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.