|Name||Kensington Quartz Diorite|
Metamorphic > Gneiss > Biotite-gneisscompositionally originally considered quartz diorite to granodiorite, now revised to tonalite. All igneous textures have been destroyed
|Comments||Name was revised according to ref MD004 as follows: Kensington Quartz Diorite as used by Hopson (1964) is here revised as Kensington Tonalite. Recent geochemical data revises its place within the IUGS rock classification scheme to a tonalite. An isotopic age of 460+/-4 Ma (Early Ordovician) for the Kensington Tonalite was determined from single crystal zircon dating (ref. MD005).|
Cleaves, E.T., Edwards, J., Jr., and Glaser, J.D., 1968, Geologic Map of Maryland: Maryland Geological Survey, Baltimore, Maryland, scale 1:250,000.
In 1995 the Water Resources Division of the U.S. Geological Survey digitized the geologic map of Maryland from the 1968 paper map (Reference MD001). Information about products from the Maryland Geological Survey can be found at http://www.mgs.md.gov/.
USGS Geologic Names lexicon found at: http://ngmdb.usgs.gov/Geolex/