Purcell Branch Formation

Purcell Branch Formation (Pavlides, 1989; 1990). Metadiamictite, characterized by a dark-gray, micaceous quartzofeldspathic matrix with a pervasive, anastomosing foliation. Mineralogy: quartz + plagioclase + muscovite + biotite (commonly retrograded to chlorite) + epidote + magnetite. Lumps of milky quartz, sparsely distributed, have undergone tectonic flattening and recrystallization; phyllitic rock chips are sparse. Exotic blocks on the order of several meters to several hundreds of meters in length include felsite, greenstone and greenschist, mafic rocks, and amphibolite; these are interpreted as derived from the Chopawamsic Formation (Pavlides, 1989).
State Virginia
Name Purcell Branch Formation
Geologic age Cambrian
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > Metasandstonemetadiamictite
Minor
Metamorphic > Metasedimentary > Metaclastic > Metaconglomerate
Comments Western Piedmont (Northern)
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 Fauquier - Prince William