Layered Porphyrobliastic Pyroxene Granulite (VAYpp;0)

State	Virginia
Name	Layered Porphyrobliastic Pyroxene Granulite
Geologic age	Proterozoic Y
Original map label	Ypp
Comments	Blue Ridge Basement Complex, Middle Proterozoic (Early or Pre-Grenville-Age) Gneisses. From expanded explanation (ref. VA002): Layered porphyroblastic pyroxene granulite. Leucocratic to mesocratic, segregation-layered quartzofeld-spathic granulite contains prominent potassium feldspar porphyroblasts; major mineralogy, quartz, plagioclase, K- feldspar, orthopyroxene or clinopyroxene, and magnetite-ilmenite; hornblende, reddish-brown biotite, and garnet are widespread minor constituents. Accessory minerals include apatite and zircon. Segregation layering is defined by millimeter- to centimeter scale quartz-feldspar- and pyoxene-rich domains; migmatitic leucosomes of alkali feldspar and blue quartz are common. This rock-type is considered to be pre-Grenville-age country rock, although no radiometric data is available.
Primary rock type	granulite
Secondary rock type
Other rock types
Lithologic constituents	Major Metamorphic > Granulite
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	Amherst - Bedford - Botetourt - Floyd - Montgomery - Roanoke - Rockbridge - Roanoke