Slab Stagnation in Australasia, and Why Convecting Material Becomes Trapped in the Mid Mantle
Abstract
A recent global study of mid-mantle discontinuities showed multiple regional reflectors at depths ranging from 800 km to 1300 km. These reflectors display a strong correlation to up and downwelling material, but the relationship to both composition and deflection of flow remains an unanswered problem. Here, we use precursors to ScSScS at short epicentral distance to explore the MTZ and mid-mantle features beneath the Australasian tectonic plate. The location allows comparison between regions with diverse subduction styles, and continental areas with no active up or downwelling. To search for ScSScS precursors and account for heterogeneous data coverage and noise, we use a new adaptive stacking technique based on a Voronoi cell parameterization. We investigate the correlation of the major MTZ discontinuities to mid-mantle reflectors in the different geodynamical contexts. We test the relationship between slab dynamics and the presence and properties of the discontinuities using synthetic seismograms built from mineral physics-based thermochemical models with different mantle compositions.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.S13C0441B
- Keywords:
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- 3613 Subduction zone processes;
- MINERALOGY AND PETROLOGY;
- 7209 Earthquake dynamics;
- SEISMOLOGY;
- 7215 Earthquake source observations;
- SEISMOLOGY;
- 8170 Subduction zone processes;
- TECTONOPHYSICS