Elk Park Plutonic Group - Biotite augen gneiss (VAYep;0)

State	Virginia
Name	Elk Park Plutonic Group - Biotite augen gneiss
Geologic age	Proterozoic Y
Original map label	Yep
Comments	Blue Ridge Basement Complex, Middle Proterozoic (Grenville-Age) Plutonic Rocks. From expanded explanation (ref. VA002): Elk Park Plutonic Group (Yep, Yec; Rankin and others, 1972; 1973) Includes augen gneiss and porphyritic gneiss (Yep), and equigranular quartz monzonite, quartz monzonite flaser gneiss, and quartz monzonite gneiss (Yec). Rocks range in composition from diorite to quartz monzonite; most are quartz monzonite in which the primary dark mineral is biotite, with or without hornblende; epidote and titanite are common accessory minerals. Porphyritic rocks contain microcline phenocrysts. Augen gneiss was probably derived from porphyritic plutonic rocks by shearing. This unit includes in part the Little River Gneiss of Dietrich (1959) and Cranberry Gneiss (Rankin and others, 1972; 1973). U-Pb zircon data from the Cranberry has been interpreted to signify ages of 1050 Ma (Davis and others, 1962) and 1080 Ma (Rankin and others, 1969).
Primary rock type	augen gneiss
Secondary rock type	quartz monzonite
Other rock types
Lithologic constituents	Major Metamorphic > Gneissaugen gneiss Minor Igneous > Plutonic > Syenitic > Quartz-monzonite
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	Carroll - Grayson - Pulaski - Smyth - Washington - Wythe