30 New advances in geological and geophysical research on the Appalachian orogen. (Posters)

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.

Monday, 23 March 2026
1:30 PM - 5:30 PM
CCC, Ballroom C

Southern Appalachian Orogen Basement Mapping Using High Resolution USGS Aeromagnetic Data, Gravity, and Seismic Profiles - South Carolina - Major Terrane Boundaries and Intrusive Plutons

Paper number: 30-1
Program: Technical Sessions
Time: 1:30 PM – 1:30 PM

Authors

Abstract

Where seismic coverage and well data are sparse, the Appalachian basement structure can be revealed with densely sampled potential field data, which correlates well with Paleozoic structural trends, folds, shear zones, and intrusive rocks. This is especially true where basement is covered by Coastal Plain sediments. This project is a collaborative effort to update the Structural Features map of South Carolina, using new aeromagnetic surveys as well as legacy gravity, seismic surveys, and well logs. These basement 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. Aeromagnetic data included new USGS high-resolution aeromagnetic data as well as legacy data. Gravity data were from the USGS state database for South Carolina and Georgia. Oasis Montaj potential field images were transferred to ArcGIS and georeferenced. Maps were created in ArcGIS. The resulting shapefile database utilizes the GeMS schema for data input – fault name, type (normal, reverse, strike-slip), age (Paleozoic, Mesozoic, Tertiary), method (mapped or geophysically inferred), shape length, and references. The methodology involved modern frequency filtering and spectral analysis methods, directional filtering, edge detection (tilt and 1st vertical derivative), and forward modeling.

Results include maps and profiles of the Central Piedmont Shear Zone, the boundary between the the Peri-Laurentia Inner Piedmont and the Peri-Gondwana Carolina superterrane, and the Modoc shear zone and Eastern Piedmont fault system, co-linear with a major ductile Paleozoic fault zone extending from Alabama to Virginia, and characterized by a zone of recent micro-earthquakes. The mapping also corrects the location of the Appalachian (Suwannee) suture (Carolina Peri-Gondwana-African Gondwana) boundary.

The new Structural Features Map and basement tectonic map of South Carolina show locations of 50 hidden (geophysically inferred) faults in the Coastal Plain and Piedmont, and igneous intrusives (several previously unknown), including 12 Granite plutons, 15 Mafic plutons, and more than 80 Diabase dikes. The faults locate potential geologic hazards, the basement maps provide settings for economic resources, and newly mapped intrusive plutons offer opportunities for CO2 sequestration and low temperature geothermal energy. Regional 2D cross sections of the Appalachian Orogen from the foreland to the Suwannee suture show that Grenville-age basement rocks extend southeastward beneath the Coastal Plain.

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

doi: 10.1130/abs/2026NE-411397

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