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Modification of Crust and Mantle Lithosphere Beneath the Southern Part of the Eastern North American Passive Margin
Author(s) -
Li Cong,
Gao Haiying
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl090555
Subject(s) - geology , lithosphere , crust , mantle (geology) , rift , passive margin , seismology , oceanic crust , seismic tomography , asthenosphere , geophysics , subduction , tectonics
The eastern North American passive margin was modified by Mesozoic rifting. Seismic data from recent deployment of onshore and offshore stations offer a unique opportunity for studying the signature of syn‐rifting and postrifting in lithospheric structures. Using full‐wave ambient noise tomography, we construct a new seismic velocity model for the lithosphere of the southeastern United States. Our model confirms an oceanic‐continental transitional crust over a ∼70 km wide zone across the coastline. Our model reveals (a) a patch of lower‐than‐average mantle lithospheric velocities underlying this transitional crust and (b) a low‐velocity column in the mantle lithosphere beneath the Virginia volcanoes. We propose that anomaly 1 represents cooled enriched mantle that underplated the thinning crust during the initial stages of rifting around 230 Ma. Anomaly 2 likely has a more recent origin in the Eocene and may result from an asthenospheric upwelling induced by a localized lithospheric delamination.