6 Geologic Maps, Geophysical Maps, 3-D Geologic Models, Digital Mapping Techniques, Map Derivatives, and Digital Map Preparation (Posters)

Thursday, 20 March 2025
8:00 AM - 12:00 PM
Shenandoah ABC

PRELIMINARY COMPILED BEDROCK GEOLOGIC MAP OF THE SOUTHERN PINES 100K, NORTH CAROLINA

Paper number: 6-9
Program: Theme Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

The N.C. Geological Survey is currently in year one of a two-year project to compile the bedrock geologic map of the Southern Pines 100K Quadrangle in the North Carolina Piedmont. The goal of year one is a complete compilation of the northern portion of the 100K. The project is partially funded by the U.S. Geological Survey, National Cooperative Geologic Mapping Program under STATEMAP. Line work from multiple legacy sources is being utilized and modified according to new field observations and edge-matched with adjacent quadrangles. Legacy geologic data sources include NCGS reconnaissance-scale data, a USGS published map, multiple master’s theses, and dissertations.

The northwest portion of the map area is underlain by the Neoproterozoic to Cambrian greenschist facies Carolina terrane, which includes the Hyco and Albemarle volcanic island arcs. The Hyco arc includes multiple subunits of the Hyco Formation. From oldest to youngest, the Albemarle arc consists of the Uwharrie, Tillery, and Cid Formations, and the newly proposed Seagrove formation (informal). The Sanford and Wadesboro sub-basins of the Deep River Triassic basin occupy much of the central to southwestern portions of the map. The eastern side of the map area is underlain by the Easternmost Carolina terrane and is separated from the rest of the Carolina terrane by the Jonesboro fault. Much of the map is overlain by Coastal Plain sediments. Bedrock beneath the Coastal Plain will be compiled using legacy boring and geophysical data and enhanced with new USGS Earth MRI funded airborne magnetic and radiometric surveys.

Recent age dates from rocks previously mapped as the Uwharrie Formation suggest that parts of the Uwharrie and the younger Tillery and Cid Formations overlap in age, thus bringing the established stratigraphy of the Albemarle arc into question. Additionally, recent detrital zircon dates indicate that large portions of the map area previously interpreted as Aaron Formation are linked to sedimentation related to the Albemarle arc. This compilation work, with additional age data collection, will hopefully bring a better understanding of a re-defined Aaron Formation and the relationship of the Uwharrie Formation with the younger units in the Albemarle arc.

Geological Society of America Abstracts with Programs. Vol. 57, No. 2

doi: 10.1130/abs/2025SE-407544

© Copyright 2025 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.