Reconciling Estimates of Mantle Viscosity Across Scales: Case Study of the Basin and Range
Abstract
Viscosity models of the upper mantle are typically derived from observations of processes that span a wide range of spatial and temporal scales such as mantle convection, glacial isostatic adjustment (GIA), post seismic deformation, xenolith deformation, etc. Estimates of mantle viscosity made from these observations often conflict although they sample the same mantle. Our goal is to reconcile these estimates and understand how and why they are different (such as different starting assumptions) with a focus on the Basin and Range in the Western United States. This widely studied region has a rich tectonic history, where all time scales and length scales come into consideration -- from global geodynamic flow of the Farallon Slab [Moucha et al 2008] to the regional GIA of Lake Bonneville [Bills et al 2007]. Using observations and estimates from the literature (such as depth to the lithosphere-asthenosphere boundary, grain size, melt amount, water content, etc.), we forward model the viscosity of the Basin and Range to explore the range and variation in space. Concurrently, we also also forward model seiemic shear wave speed with the same parameters following Jackson and Faul (2010) and use the result to minimize against observations of seismic shear wave speed. We present and discuss the influence of various parameters on viscosity and their uncertainty in the Basin and Range region.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMDI31A2620L
- Keywords:
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- 1038 Mantle processes;
- GEOCHEMISTRYDE: 7215 Earthquake source observations;
- SEISMOLOGYDE: 7294 Seismic instruments and networks;
- SEISMOLOGYDE: 8124 Earth's interior: composition and state;
- TECTONOPHYSICS