Ashe Formation - Moneta Gneiss

Moderate-olive-brown to dusky yellowish- green to black-and-white-banded, medium- to fine-grained biotite-hornblende gneiss, with interlayers of light gray, fine-grained quartz-feldspar gneiss, amphibolite, and mica schist. Felsitic crystal tuff breccia, feldspathic conglomerate, and mafic and felsic dikes and sills are recognized within the Moneta, especially along the James River west of Lynchburg. Wang and Glover (1991) recognized two kinds of mafic metavolcanic rocks in this unit, lavas and tuffs. The lavas have well-preserved hyaloclastic textures; metatuffs commonly contain delicate mineral segregation lamination. Mineralogy: (1) quartz + plagioclase + microcline + biotite + muscovite + garnet + magnetite-ilmenite; (2) hornblende + plagioclase + biotite + quartz + magnetite-ilmenite + titanite; (3) hornblende + plagioclase + garnet + biotite + magnetiteilmenite. Geophysical signature: broad, elongate, positive magnetic anomaly. Numerous pegmatite dikes and sills concentrated within the hornblende biotite gneiss were mined for feldspar in the area between Moneta and Forest where the unit was first described by Pegau (1932). In the Lynchburg area the Moneta was mapped as Reusens Migmatite by Brown (1958). It was interpreted to be a Late Precambrian volcanic-sedimentary complex by Conley and Henika (1970) and Wang and Glover (1991). The Moneta is here assigned to the Lynchburg Group because it has an intertonguing re la tion ship with basal conglomeratic Lynchburg rocks and with similar rocks in the base of the Ashe Formation southwest of Lynchburg.
State Virginia
Name Ashe Formation - Moneta Gneiss
Geologic age Proterozoic Z
Lithologic constituents
Major
Metamorphic > Gneiss > Hornblende-gneissmafic gneiss
Comments Lynchburg Group; Blue Ridge Anticlinorium (Southwest)
References

Virginia Division of Mineral Resources, 1993, Geologic Map of Virginia: Virginia Division of Mineral Resources, scale 1:500,000.

Virginia Division of Mineral Resources, 2003, Digital Representation of the 1993 Geologic Map of Virginia, Publication 174, CD ROM (ISO-9660) contains image file, expanded explanation in pdf, and ESRI shapefiles, scale 1:500,000.

NGMDB product
Counties Amherst - Bedford - Franklin - Lynchburg