Improved Tomography of the Columbia River Flood Basalts and Central Idaho Regions Reveals New Geometries for the Fast Anomalies in the Upper Mantle
Abstract
We present new high-resolution P and S tomography models of the upper mantle beneath the Columbia River flood basalts and central Idaho. Our models incorporate data from the USArray-TA stations, regional deployments, and the newly completed Wallowa experiment. Travel times are corrected for crust, and modeling incorporates iterative 3-D ray-tracing and finite-frequency effects. We observe the Wallowa (NE Oregon) and Siletzia (central Idaho) mantle anomalies extending down to 350 km, with no clear connection between them. These anomalies are also separate from a fast anomaly located in the top 100 km beneath the Atlanta lobe of the Idaho batholith. We relate these fast anomalies to slab rollback and delamination. The Siletzia anomaly is interpreted as Farallon lithosphere, perhaps including some delaminated North American lithosphere. The fast Wallowa anomaly probably is Farrallon lithosphere that delaminated from south to north in the last 17 Ma, initiated by Yellowstone plume arrival to SE Oregon. Our preferred interpretation for the shallow Atlanta-lobe anomaly is a fragment of North American lithosphere isolated during passage of the Yellowstone hotspot.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.T43F0476S
- Keywords:
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- 7208 Mantle;
- SEISMOLOGYDE: 8120 Dynamics of lithosphere and mantle: general;
- TECTONOPHYSICSDE: 8125 Evolution of the Earth;
- TECTONOPHYSICSDE: 8159 Rheology: crust and lithosphere;
- TECTONOPHYSICS