Imaging the Crust and Upper Mantle Beneath Columbia River Flood Basalts With Ambient Seismic Noise, Regional and Teleseismic Events and Converted Phases

Date: 4/26/2019

Time: 04:30 PM

Room: Puget Sound

The dynamics of flood basalt events are not well understood. The latest flood basalt eruption is the Columbia River Basalts (CRB), which initiates of the Yellowstone hotspot track. This event initiated near the southern Oregon state line and propagated north, possibly due to the foundering and sinking of large portions of the lithosphere into the asthenosphere. In the process, geochemical evidence suggest a large crustal magma chamber was established in east-central Oregon.To investigate the link between the CRB and the lithospheric foundering, we use data of from 380 stations, including the newly completed Wallowa experiment, to generate a detailed 3D shear-wave velocity model of the region by inverting waveform data of regional and teleseismic events and surface wave data extracted from the ambient seismic noise. In addition, we use the discrepancy between horizontally and vertically polarized shear wave velocities in the crust to quantify radial anisotropy and illuminate any structural fabric that might be related with the areal extent of the magma chamber and the existence of a descending pluton beneath it. To further refine our model, we use an array-based receiver function (RF) deconvolution method to generate a sharp and coherent image of the structure beneath the CRBs. Our study provides new insights into the role of lithospheric foundering on flood basalt magmatism.

Presenting Author: Jorge C. Castellanos

Authors