"The Appalachians and how they got that way: New insights into the structure and dynamics of eastern North America from the EarthScope project"
Speaker: Maureen Long (Yale)
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. It is poorly known, however, 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 has opened 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, with a focus on the central Appalachians and on New England. I will present new results from the MAGIC project, a multidisciplinary collaboration that includes a USArray Flexible Array deployment across the central Appalachians in Virginia, West Virginia, and Ohio. We find evidence for lithospheric loss beneath the MAGIC study region, along with evidence for lithospheric deformation associated with orogenesis and rifting. We have also identified a prominent eastward-dipping intracrustal feature beneath Ohio and West Virginia, which may represent the relict Grenville deformation front at depth. Beneath New England, USArray data are shedding light on the characteristics and origin of a low-velocity anomaly in the upper mantle, which may correspond to an edge-driven convection cell.
About this Series
Weekly talks given by leading thinkers in the areas of geology, geophysics, geobiology, geochemistry, atmospheric science, oceanography, climatology, and planetary science. Lectures take place on Wednesdays from 3:45pm in MIT Building 54 room 915, unless otherwise noted.
