Robertson River Igneous Suite (VAZrw;0)

State	Virginia
Name	Robertson River Igneous Suite
Geologic age	Proterozoic Z
Original map label	Zrw
Comments	Blue Ridge Basement Complex, Late Proterozoic Igneous. From expanded explanation (ref. VA002): White Oak Alkali Feldspar Granite. Light-gray to gray, coarse-grained, inequigranular alkali feldspar granite composed of microcline microperthite, quartz, and plagioclase, with hastingsitic amphibole, allanite, fluorite, stilpnomelane, zircon, chlorite, and calcite. Unaltered surfaces display pronounced vitreous luster. Granite typically occurs intermixed with light-gray, fine-grained, mineralogically identical alkali feldspar granite that is locally younger. The unit has been dated at 725 +/- 8 Ma (U-Pb zircon; Tollo and Aleinikoff, in press).
Primary rock type	granite
Secondary rock type
Other rock types
Lithologic constituents	Major Igneous > Plutonic > Granitic > Granite
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	Albemarle - Greene - Madison