Journal
EARTH AND PLANETARY SCIENCE LETTERS
Volume 462, Issue -, Pages 66-75Publisher
ELSEVIER
DOI: 10.1016/j.epsl.2017.01.009
Keywords
Appalachian Mountains; Appalachian Orogen; Central Atlantic Magmatic Province; topographic rejuvenation; magnetotellurics
Categories
Funding
- NSF [EAR1053628, 1314109-DGE]
- Division Of Earth Sciences
- Directorate For Geosciences [1053628] Funding Source: National Science Foundation
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We present the first three-dimensional view of the lithospheric electrical conductivity structure beneath southeastern North America. By inverting EarthScope long-period magnetotelluric (MT) data, we obtain an electrical conductivity image that provides new insights into both the architecture of the Appalachian Orogen and the cryptic post-rifting geodynamic history of the southeastern United States. Our inverse solutions reveal several elongate electrically conductive features that we interpret as major terrane sutures within the Appalachian Orogen. Most significantly, we resolve a highly electrically resistive layer that extends to mantle depths beneath the modern Piedmont and Coastal Plain physiographic provinces. As high resistivity values in mantle minerals require cold mantle temperatures, the MT data indicate that the sub-Piedmont thermal lithosphere must extend to greater than 200 km depth. This firm bound conflicts with conclusions from seismic results. The boundary between the anomalously thick, resistive sub-Piedmont lithosphere and the relatively thin, moderately conductive sub-Appalachian lithosphere corresponds within resolution to the modern Appalachian topographic escarpment. This newly recognized contrast in lithospheric properties likely has important implications for Appalachian topographic rejuvenation. (c) 2017 Elsevier B.V. All rights reserved.
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