25-1 PRELIMINARY REVIEW OF GEOCHEMICAL, PETROLOGICAL, AND STRUCTURAL PROFILE OF GNEISSIC OUTCROP WITHIN ASHE METAMORPHIC SUITE IN THE SOUTHERN BLUE RIDGE MOUNTAINS

Session: New Research in the Appalachian-Ouachita Orogen: Integrated studies from the Foreland to the Hinterland (Posters)

Presenting Author:

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Abstract:

The Ashe Metamorphic Suite spans a large region of Western North Carolina and continues into Virginia. The suite is known for its complicated formation history and is composed predominantly of mica and biotite schists, amphibolite, and hornblende gneiss. We focused our study on a small roadcut outcrop near Tuckasegee, NC in the southwestern part of the formation. Our preliminary study aims to contribute to better understanding evidence for metamorphism and deformation of the Suite using various petrographic and geochemical methods.

We focused petrographic investigation on a biotite schist and two sets of felsic material from the same outcrop. Photomicrographs show that the felsic samples are composed of small-medium sized quartz, plagioclase, microcline, and muscovite grains, whereas the schist is dominated by biotite; one felsic sample contained abundant opaques along grain boundaries and larger fractures in the rock. A Thermo Fisher Apreo scanning electron microscope (SEM) was used to identify the chemical composition of specific minerals and oxides within each sample along with backscattered electron images. Orientation and shape data was derived from the schist using an outlining process and input into ShapeCalc and CSDCorrections software. In addition, eight hand-samples were powdered for geochemical analysis with hand-held X-Ray Fluorescence (XRF) to obtain major, minor, and trace elements as well as X-Ray Diffraction (XRD) to identify possible mineral profiles.

Our preliminary work suggests, in addition to the dominant mineralogy, the presence of hexagonal apatite and euhedral zircons with pleochroic halos, myrmekites, and oriented muscovite inclusions within plagioclase. Additional deformation microstructures found in the felsic thin-sections include chessboard sub-grain boundaries in quartz, deformation twinning in plagioclase, sutured and bulging grain boundaries in quartz; the biotite schist displays a preferred orientation within a lepidoblastic texture. Work continues to identify the opaques, but the XRF data and SEM X-ray maps indicate a higher presence of sulfur, cobalt, and iron in the opaque-bearing sample compared to the other splits. These results reflect the multi-stage deformation and potential metasomatism events of this outcrop and further contribute to the understanding of the Suite.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1, 2026

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