Ambient Noise Tomography in Northeastern United States

Date: 4/25/2019

Time: 06:00 PM

Room: Grand Ballroom

The tectonic structure of the crust in the northeast region of the U.S. is both compositionally complex and tectonically stable relative to lithospheric structures that formed during earlier geological periods. Data from the EarthScope Transportable Array collected in 2014 are used to calculate a three-dimensional shear velocity model of the crust and upper mantle in the northeastern United States. We apply ambient noise tomography and receiver function techniques to determine the Rayleigh wave phase velocities and the 3D inversion using crustal thicknesses determined by Lin 2014. The spatial distribution of the structures determined by this model is well-correlated to the observed geology at the surface, including the sedimentary coastal regions, the Appalachian orogeny, and the New England area.

The lateral distribution and depth of several slow anomalies, determined by the tomographic inversion, within the crust of the middle Appalachians correlate to Eocene volcanism. This is consistent with tomographic models presented by Porter 2016 and Wagner 2017. Since the model is highly sensitive to the crustal thickness, higher-resolved Moho depths used in this research provide a better explanation for the material below these volcanic structures. The tomography shows groups of fast velocities in the upper mantle in these regions, indicating the presence of denser materials that have been supporting the gradual volcanism since the Eocene.

A fast anomaly detected in the inversion, close to the surface of the New England crust, correlates with the igneous intrusions generated by the Great Meteor Hotspot, which formed approximately 100-130Ma. Since the initial penetration of this hotspot through the New England crust, the upper layers have cooled, while the base of the upper mantle consists of higher temperatures.

Presenting Author: Tianqi Wang

Authors