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Mineral Resources > Online Spatial Data > Geology > by state > North Carolina Geology

Geologic units in Buncombe county, North Carolina

[Additional scientific data in this geographic area]

Biotite Granitic Gneiss (Middle Proterozoic) at surface, covers 5 % of this area

Biotite Granitic Gneiss - unconformity; pinkish gray to light gray, massive to well-foliated, granitic to quartz monzonitic; includes variably mylonitized orthogneiss and paragneiss, interlayered amphibolite, calc-silicate rock, and marble. Includes granites of the Bryson City area, Straight Fork window, and Elk Park Plutonic Suite.

Lithology: granitic gneiss; amphibolite; calc-silicate rock; marble

Biotite Gneiss and Schist (Cambrian/Late Proterozoic) at surface, covers 1 % of this area

Biotite Gneiss and Schist - inequigranular, locally abundant potassic feldspar and garnet; interlayered and gradational with calc-silicate rock, sillimanite-mica schist, mica schist, and amphibolite. Contains small masses of granitic rock.

Lithology: biotite gneiss; mica schist; amphibolite; calc-silicate rock; granite

Henderson Gneiss (Cambrian) at surface, covers 5 % of this area

Henderson Gneiss (524 my) - monzonitic to granodioritic; inequigranular.

Lithology: gneiss

Migmatitic Biotite-Hornblende Gneisses (Middle Proterozoic) at surface, covers 9 % of this area

Migmatitic Biotite-Hornblende Gneisses (1214 my) - unconformity; layered biotite-granite gneiss, biotite-hornblende gneiss, amphibolite, calc-silicate rock; locally contains relict granulite facies rock.

Lithology: gneiss; amphibolite; calc-silicate rock; granulite

Ashe Metamorphic Suite and Tallulah Falls Formation; Muscovite-biotite gneiss (Late Proterozoic) at surface, covers 51 % of this area

Muscovite-biotite gneiss - locally sulfidic; interlayered and gradational with mica schist, minor amphibolite, and hornblende gneiss.

Lithology: gneiss; mica schist; amphibolite

Meta-ultramafic Rock (Paleozoic/Late Proterozoic) at surface, covers 0.2 % of this area

Meta-ultramafic Rock - metamorphosed dunite and peridotite; serpentine, soapstone, and other altered ultramafic rock. Only larger bodies shown.

Lithology: metamorphic rock; serpentinite

Alligator Back Formation; Gneiss (Late Proterozoic) at surface, covers < 0.1 % of this area

Gneiss - finely laminated to thin layered; locally contains massive gneiss and micaceous granule conglomerate; includes schist, phyllite, and amphibolite.

Lithology: gneiss; conglomerate; schist; phyllite; amphibolite

Rocks of Brevard Fault Zone (Uncertain, possibly Permian or Devonian) at surface, covers 3 % of this area

Rocks of Brevard Fault Zone - "fish scale" schist and phyllonite, graphitic; interlayered with feldspathic metasandstone, marble lenses.

Lithology: schist; phyllonite; metasedimentary rock; marble

Granite Gneiss (Silurian/Ordovician) at surface, covers 1 % of this area

Granite Gneiss (438 my) - poorly foliated; interlayered with biotite augen gneiss.

Lithology: granitic gneiss; augen gneiss

Coweeta Group; Biotite Gneiss (Middle/Late Proterozoic) at surface, covers 4 % of this area

Biotite Gneiss - migmatitic; interlayered and gradational with biotite-garnet gneiss and amphibolite; locally abundant quartz and alumino-silicates. Stratigraphic position uncertain.

Lithology: biotite gneiss; amphibolite

Amphibolite (Middle Proterozoic) at surface, covers 2 % of this area

Amphibolite - unconformity; equigranular, massive to well foliated, interlayered, rarely discordant, metamorphosed intrusive to extrusive mafic rock; may include metasedimentary rock.

Lithology: amphibolite; metasedimentary rock

Ocoee Supergroup; Great Smokey Group, undivided (Late Proterozoic) at surface, covers 0.1 % of this area

Great Smokey Group, undivided - thick metasedimentary sequence of massive to graded beds of metagraywacke and metasiltstone with interbedded graphitic and sulfidic slate and schist.

Lithology: metasedimentary rock; slate; schist

Ashe Metamorphic Suite and Tallulah Falls Formation; Metagraywacke (Late Proterozoic) at surface, covers 19 % of this area

Metagraywacke - foliated to massive, locally conglomeratic; interlayered and gradational with mica schist, muscovite-biotite gneiss, and rare graphitic schist.

Lithology: metasedimentary rock; mica schist; biotite gneiss