1 New advances in geological and geophysical research on the Appalachian orogen.

We invite contributions that discuss new research on the Appalachian orogen. Submissions should include, but are not limited to, geological or geophysical studies or works comprising a combination of both methods.

Sunday, 22 March 2026
8:00 AM - 12:00 PM
CCC, Room 22/23

Subsurface Appalachian Orogen Basement Mapping Using New High Resolution USGS Aeromagnetic Data, Gravity, and Seismic Profiles - South Carolina - Corrected Location of African Suture

Paper number: 1-2
Program: Technical Sessions
Time: 8:25 AM – 8:45 AM

Authors

Abstract

New USGS aeromagnetic surveys illuminate the structural geology of the basement rocks buried under thick Coastal Plain sediments in South Carolina. These rocks record the final Pangaea supercontinent collision of the Appalachian Orogen, as well as Mesozoic rifting, massive igneous intrusions, and the formation of the Atlantic rifted margin. Potential field data correlates well with pre-Cenozoic structural trends, folds, shear zones, and intrusive rocks. This project was a collaborative effort to update the Structural Features map of South Carolina, using the new aeromagnetic surveys as well as legacy gravity, seismic surveys, and well logs. Important new results were obtained using modern frequency filtering and spectral analysis methods, directional filtering, edge detection (tilt and 1st vertical derivative), and forward modeling.

One important new result is the corrected location of the Appalachian (Suwannee) suture (Carolina Peri-Gondwana-African Gondwana) boundary. Most previous attempts to define the Suture were misplaced, based only on Total Magnetic Intensity maps. When the magnetic data is frequency filtered, however, deformed NE-trending Peri-Gondwana Carolina superterrane rocks can be mapped southeastward to the boundary with undeformed or mildly deformed Suwannee African rocks from North Carolina to Georgia. One implication of this result is that the 1886 Charleston earthquake occurred in African (Suwannee terrane) basement, not in Peri-Gondwana basement as commonly assumed.

There is much public interest in a zone of recent micro-earthquake activity near Elgin South Carolina, associated with the Eastern Piedmont fault system. Filtered magnetic data indicates that the micro-earthquake zone is adjacent to either a left-stepping fault or a p-ramp structure  south of the late Paleozoic dextral Modoc shear zone.

The new Structural Features Map and basement tectonic map of South Carolina have socio-economic value by expanding the knowledge of the geologic framework of the area, informing about potential geologic hazards, and expanding current understanding of economic resources. Newly mapped intrusive plutons offer opportunities for CO2 sequestration and low temperature geothermal energy. 2D cross sections of the Appalachian Orogen from the foreland to the Suwannee suture show the orogeny profile pre- and post- collision.

 

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411206

© Copyright 2026 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.