Buckingham Complex - Metamorphosed mafic and ultramafic rocks

Dark greenish-gray, massive to layered, coarse-grained metagabbro, with metapyroxenite and metaperidotite layers. Early layered units are cut by late-stage aplitic granodiorite veins and dikes. Screens of metasedimentary country rocks separate differentiated metaperidotite-metagabbro sills. Younger quartz diorite pluton (PzZbq) partially brecciates older mafic rocks. Mineralogy (secondary minerals in parentheses): metaperidotite, orthopyroxene + clinopyroxene + olivine + magnetite (+ tremolite-actinolite + chlorite + serpentine + talc + epidote + magnetite + calcite); metapyroxenite, orthopyroxene + clinopyroxene + hornblende + magnetite (+ chlorite + talc + plagioclase + epidote + quartz + magnetite); metagabbro, hornblende + clinopyroxene + orthopyroxene + biotite + plagioclase + magnetite (+ biotite + chlorite + epidote + muscovite+ quartz + garnet). Geophysical signature: Positive magnetic anomalies are associated with mafic and ultramafic sills.
State Virginia
Name Buckingham Complex - Metamorphosed mafic and ultramafic rocks
Geologic age Proterozoic Z-Pennsylvanian
Lithologic constituents
Major
Metamorphic > Metaigneous > Metaintrusive > Metagabbro
Minor
Metamorphic > Metaigneous > Metaintrusive > Metaultramafic > Metapyroxenite
Metamorphic > Metaigneous > Metaintrusive > Metaultramafic > Metaperidotite
Comments Western Piedmont (Southwest and Central)
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 Buckingham