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Crustal Structure Beneath the Northern Appalachians and the Eastern Grenville Province
  • Omid Bagherpur Mojaver,
  • Fiona Ann Darbyshire
Omid Bagherpur Mojaver
Centre de recherche Geotop, Université du Québec à Montréal

Corresponding Author:omid.bagherpur@gmail.com

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Fiona Ann Darbyshire
Centre de recherche GEOTOP, Université du Québec à Montréal (UQAM), Canada
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Southeastern Canada and the northeastern USA include terranes that were tectonized since the Archean, making this region an excellent place to investigate the evolution of continental crust. Our study area covers the Archean southeastern Superior Province, the Proterozoic eastern Grenville, and the Phanerozoic northern Appalachians comprising terranes with either Peri-Laurentian or Peri-Gondwanan heritage. Adopting a Rayleigh wave ambient noise tomography method, we used noise data recorded between 2013 and 2015, and obtained high resolution anisotropic tomographic images of the crust enabling us to discuss tectonic implications. The azimuthal anisotropy orientations follow a dominant NE-SW trend across the study area, but some localized changes of anisotropy direction in the Bay of Fundy and across the Appalachian front are observed. The crust beneath the older Superior and Grenville provinces is generally fast, whereas the Appalachians include strong slow anomalies, especially at upper crustal depths, where they represent thick sedimentary basins beneath the St. Lawrence valley, the Gulf of St. Lawrence and the Bay of Fundy. We suggest that the boundary between the Peri-Laurentian and the Peri-Gondwanan terranes at depth is marked by a Moho-offset feature observable in our models. A generally similar crustal seismic signature for the youngest two easternmost tectonic domains suggest that they were never separated by a wide ocean basin. Our results provide important evidence for evolution of the continental crust during and after accretionary/collisional episodes in the study area.
Jan 2022Published in Journal of Geophysical Research: Solid Earth volume 127 issue 1. 10.1029/2021JB023246