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Geoelectric constraints on the Precambrian assembly and architecture of southern Laurentia

August 27, 2022

Using images from an updated and expanded three-dimensional electrical conductivity synthesis model for the contiguous United States (CONUS), we highlight the key continent-scale geoelectric structures that are associated with the Precambrian assembly of southern Laurentia. Conductivity anomalies are associated with the Trans-Hudson orogen, the Penokean suture, the ca. 1.8–1.7 Ga Cheyenne belt and Spirit Lake tectonic zone, and the Grenville suture zone; the geophysical characteristics of these structures indicate that the associated accretionary events involved the closure of ancient ocean basins along discrete, large-scale structures. In contrast, we observe no large-scale conductivity anomalies through the portion of southern Laurentia that is generally viewed as composed of late Paleoproterozoic–early Mesoproterozoic accretionary crust. The lack of through-going conductors places constraints on the structure, petrology, and geodynamic history of crustal growth in southern Laurentia during that time period. Overall, our model highlights the enigmatic nature of the concealed Precambrian basement of much of southern Laurentia, as it in some places supports and in other places challenges prevailing models of Laurentian assembly. The revised CONUS electrical conductivity model thus provides important constraints for testing new models of Precambrian tectonism in this region.

Citation Information

Publication Year 2022
Title Geoelectric constraints on the Precambrian assembly and architecture of southern Laurentia
DOI 10.1130/2022.1220(13)
Authors Benjamin Scott Murphy, Paul A. Bedrosian, Anna Kelbert
Publication Type Book Chapter
Publication Subtype Book Chapter
Index ID 70236495
Record Source USGS Publications Warehouse
USGS Organization Geologic Hazards Science Center, Geology, Geophysics, and Geochemistry Science Center