Dr. Maureen Long : The Appalachians... (14-10-2016)

 

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Dr. Maureen Long (Yale University) - Earthscope Lecture Series

The Appalachians and how they got that way: Structure and dynamics of eastern North America

Vendredi 14 octobre 2016 à 15h30 / Friday, October 14, 2016, 3:30 pm

Redpath Museum Auditorium, Université McGill

Résumé/Abstract: 

The surface geology of eastern North America is extraordinary in its complexity. This complexity reflects a wide range of tectonic processes that have operated in the region over the past billion years, including episodes of subduction and rifting associated with two complete Wilson cycles of supercontinent assembly and breakup. However, it is unknown how the deep crust and mantle lithosphere have responded to these tectonic forces over time; furthermore, the persistence of Appalachian topography through time remains a major outstanding problem in the study of landscape evolution.
The deployment of the EarthScope USArray in eastern North America is opening up new frontiers in the study of the deep structure and dynamics of the crust, mantle lithosphere, and asthenospheric mantle beneath this passive continental margin. In this talk I will discuss recent results from the EarthScope project on the structure of the crust and upper mantle beneath eastern North America. These include new results from the MAGIC project, a multidisciplinary collaboration that includes a USArray Flexible Array deployment across the Appalachians in Virginia, West Virginia, and Ohio. In particular, new constraints on seismic anisotropy (that is, the directional dependence of seismic wavespeeds) beneath eastern North America are yielding new understanding of the deformation of the crust and mantle lithosphere during past tectonic episodes, as well as the pattern of mantle flow beneath the present-day passive margin and its possible effects on surface topography.