Buffards Formation (VAObf;0)

State	Virginia
Name	Buffards Formation
Geologic age	Ordovician
Original map label	Obf
Comments	Central Virginia Volcanic-Plutonic Belt. From expanded explanation (ref. VA002): Buffards Formation (Brown, 1969). Includes greenish-gray conglomeratic quartzose muscovite schist containing ellipsoidal clasts of milky quartz, dusky-red quartzite, dark gray aphanitic rock, and greenish-gray phyllite; greenish-gray chlorite-muscovite schist with medium to fine, grayish-blue quartz grains; grayish-green chlorite-muscovite phyllite; biotite-muscovite-quartz schist. Mineral assemblages are those found in Arvonia slates and porphyroblastic schists. Conglomeratic schist occurs along the western margin of the principal Buffards outcrop belt, and as discontinuous lenses too small to show at 1:500,000 scale, at or near the western margin (stratigraphic base) of the Arvonia slate outcrop belt (Oa) (Evans and Marr, 1988). Although Brown (1969) in defining the Buffards Formation considered these rocks to be a pyroclastic deposit stratigraphically above the Arvonia Formation, other workers have interpreted Buffards rocks to be at a lower stratigraphic position relative to the Arvonia. Conley and Marr (1980) considered the Buffards part of the Chopawamsic Formation, unconformably below the Arvonia. Stose and Stose (1948) and Evans and Marr (1988) considered the Buffards to be stratigraphically at or near the base of the Arvonia Formation. Buffards conglomeratic schists contain tuffaceous and ferruginous-quartzite clasts similar to rocks that occur in the Chopawamsic Formation; this is consistent with the Buffards being derived in part from, and deposited unconformably on, the Chopawamsic. The chaotic, locally graded nature of the deposits is suggestive of a submarine fan channel deposit.
Primary rock type	conglomerate
Secondary rock type	schist
Other rock types	phyllite
Lithologic constituents	Major Metamorphic > Schist Sedimentary > Clastic > Conglomeratemicaceous conglomerate Minor Metamorphic > Metasedimentary > Metaclastic > Phyllite
Map references	Digital Representation of the 1993 Geologic Map of Virginia", 2003, CD ROM (ISO-9660) contains image file, expanded explanation in pdf, and ESRI shapefiles, viewing software not included. This is a digital version of "Geologic Map of Virginia" published in 1993. Available from: https://www.dmme.virginia.gov/commerce/ [https://www.dmme.virginia.gov/commerce/]
Unit references	Virginia Division of Mineral Resources, 1993, Geologic Map of Virginia: Virginia Division of Mineral Resources, scale 1:500,000 Digital Representation of the 1993 Geologic Map of Virginia - expanded explanation: 2003, Commonwealth of Virginia, Department of Mines, Minerals, and Energy, Divsion of Mineral Resources, Publication 147, 85 pp Digital Representation of the 1993 Geologic Map of Virginia", 2003, CD ROM (ISO-9660) contains image file, expanded explanation in pdf, and ESRI shapefiles, viewing software not included. This is a digital version of "Geologic Map of Virginia" published in 1993. Available from: https://www.dmme.virginia.gov/commerce/ [https://www.dmme.virginia.gov/commerce/]
Geographic coverage	Buckingham