Seismic wave speed structure of the Ontong Java Plateau
Date of Original Version
The Ontong Java Plateau (OJP) represents the result of a significant event in the Earth's geologic history. Limited geophysical and geochemical data, as well as the plateau's relative isolation in the Pacific ocean, have made interpretation of the modern day geologic structure and its 120 Ma formation history difficult.Here we present the highest resolution image to date of the wave speed structure of the OJP region. We use a data set that combines Rayleigh waves extracted from both ambient noise and earthquake waveforms and an iterative finite-frequency tomography methodology. The combination of datasets allow us to best exploit the limited station distribution in the Pacific and image wave speed structures between 35 km and 300 km into the Earth.We image a region of fast shear wave speeds, greater than 4.75 km/s, that extends to greater than 100km beneath the plateau. The wave speeds are similar to as observed in cratonic environments and are consistent with a compositional anomaly that resulted from the residuum of eclogite entrainment during the plateau's formation.The combination of our imaged wave speed structure and previous geochemical work suggest that a surfacing plume head entrained eclogite from the deep mantle and accounts for the anomalous buoyancy characteristics of the plateau and observed fast wave speeds.
Publication Title, e.g., Journal
Earth and Planetary Science Letters
Covellone, Brian M., Brian Savage, and Yang Shen. "Seismic wave speed structure of the Ontong Java Plateau." Earth and Planetary Science Letters 420, (2015). doi: 10.1016/j.epsl.2015.03.033.