Imaging the meso-scale structure and dynamics of the upper mantle beneath the Atlantic ocean
Abstract
Over the last decades, seismic tomography has provided important constraints on the long-wavelength structure of the mantle and its planform of convection. However, much is yet not well understood about the dynamic interaction of tectonic plates and deep mantle circulation at intermediate wavelengths (below plate-scale). In particular, a better understanding of the oceanic upper mantle could potentially help unraveling the relationships between different scales of mantle convection, hotspot volcanism, and surface observables (e.g., MORB geochemistry and bathymetry). In this context, we here present a new tomographic model of the shear-wave velocity and radial anisotropy structure underneath the southern Atlantic ocean constructed from the inversion of surface and body waves waveforms down to 30s period. Preliminary results suggest the existence of quasi-periodically distributed low-velocity regions in the upper mantle (200-350 km depth) organized in horizontally elongated bands parallel to the direction of absolute plate motion. These structures are believed to indicate the influx of material from deep mantle sources (i.e. plumes) which is deflected horizontally beneath oceanic plates (French et al, 2013). In addition, we explore the relationship between these low-velocity regions to features observed in geodynamic simulations, as well as different surface observables (e.g., subsidence rates, dynamic topography, gravity, and geochemical signals along mid-ocean ridges) to investigate links between seismic velocities, mantle temperature, composition, and mantle flow beneath mid-ocean ridges and ocean basins.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMDI0160009M
- Keywords:
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- 1025 Composition of the mantle;
- GEOCHEMISTRY;
- 3999 General or miscellaneous;
- MINERAL PHYSICS;
- 3621 Mantle processes;
- MINERALOGY AND PETROLOGY;
- 7208 Mantle;
- SEISMOLOGY