Seismic structure of the central US crust and upper mantle: Uniqueness of the Reelfoot Rift

Earth and Planetary Science Letters
By:  and 

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Abstract

Using seismic surface waves recorded with Earthscope's Transportable Array, we apply surface wave imaging to determine 3D seismic velocity in the crust and uppermost mantle. Our images span several Proterozoic and early Cambrian rift zones (Mid-Continent Rift, Rough Creek Graben—Rome trough, Birmingham trough, Southern Oklahoma Aulacogen, and Reelfoot Rift). While ancient rifts are generally associated with low crustal velocity because of the presence of thick sedimentary sequences, the Reelfoot Rift is unique in its association with low mantle seismic velocity. Its mantle low-velocity zone (LVZ) is exceptionally pronounced and extends down to at least 200 km depth. This LVZ is of variable width, being relatively narrow (∼50km wide) within the northern Reelfoot Rift, which hosts the New Madrid Seismic Zone (NMSZ). We hypothesize that this mantle volume is weaker than its surroundings and that the Reelfoot Rift consequently has relatively low elastic plate thickness, which would tend to concentrate tectonic stress within this zone. No other intraplate ancient rift zone is known to be associated with such a deep mantle low-velocity anomaly, which suggests that the NMSZ is more susceptible to external stress perturbations than other ancient rift zones.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Seismic structure of the central US crust and upper mantle: Uniqueness of the Reelfoot Rift
Series title Earth and Planetary Science Letters
DOI 10.1016/j.epsl.2013.05.042
Volume 402
Year Published 2014
Language English
Publisher Elsevier
Contributing office(s) Earthquake Science Center
Description 10 p.
First page 157
Last page 166
Country United States
Other Geospatial Reelfoot Rift