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

Saturday, 18 March 2023
1:30 PM - 5:30 PM
Grand Ballroom A–D

COMPILED STRUCTURAL DATA FOR CHATHAM COUNTY, NORTH CAROLINA - UTILIZING GIS TO UNRAVEL STRUCTURAL GEOLOGY PROBLEMS

Paper number: 36-14
Program: Theme Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

The NC Geological Survey (NCGS) recently concluded detailed geologic mapping in Chatham County, NC with partial support from STATEMAP. We have collected structural data from parts of 14 quadrangles by 9 geologists over a 25-year period. This data has been compiled into one GIS database currently consisting of 25,120 attributes. This dataset includes over 837 primary features, 3,843 foliation and cleavage measurements, and 5,343 joints. This data, used in conjunction with the detailed geology polygons, appears to have great potential for various structural analyses over larger areas and provides the ability to easily share the dataset with collaborators.

Geologically, the majority of Chatham County is underlain by the Neoproterozoic to Cambrian Carolina terrane and its three lithotectonic assemblages, the Hyco arc, the Aaron Formation of the Virgilina Sequence, and the Albemarle arc, which consists of various metamorphosed intrusive, extrusive, and volcanogenic sedimentary rocks. The eastern portion of the county is underlain by Triassic sediments of the Deep River basin. Abundant evidence of brittle faulting at the outcrop scale and large-scale lineaments are present in the map area. The brittle faulting and lineaments are interpreted to be associated with Mesozoic extension. Diabase dikes of Jurassic age intrude the crystalline rocks of the map area.

Preliminary observations utilizing this dataset in GIS include: 1) primary bedding within the Carolina terrane rocks are concentrated along the flanks of volcanic centers probably representing distal sedimentation. 2) local foliation trends show significant variation from the regional trend. This may be due to overprinting relationships of multiple deformation events and/or rotation of foliation by brittle faulting. 3) symbolization of dip inclinations with varying color schemes and sizes highlight areas of structural complexity that could use further investigation.

Geological Society of America Abstracts with Programs. Vol. 55, No. 2

doi: 10.1130/abs/2023SE-385463

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