|Geologic age||Middle Proterozoic|
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)Generally dark-gray basalt, andesite, and felsite flows and subordinate interflow sedimentary rocks
Igneous > Volcanic > Mafic-volcanic > Andesite (Flow)Generally dark-gray basalt, andesite, and felsite flows and subordinate interflow sedimentary rocks
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow)
Sedimentary > Clastic > Mixed-clasticGenerally dark-gray basalt, andesite, and felsite flows and subordinate interflow sedimentary rocks
|Comments||Previously called the "unnamed formation", including on paper map of Sims (1992). The unit symbol on that map is "Yu". This has been replaced by the naming the unit, the Porcupine Volcanics, and using the symbol "Ypv" as was done in the digital map of Cannon et al. (1997). Unit description here is from the unit description of "Yu" on Sims (1992)|
Zartman and others, 1997, U-Th-Pb zircon ages of some Keweenawan Supergroup rocks from the south shore of Lake Superior: Canadian Journal of Earth Sciences, v. 34, p. 549-561.
Sims, P.K., 1992, Geologic map of Precambrian rocks, southern Lake Superior region, Wisconsin and northern Michigan: U.S. Geological Survey Miscellaneous Investigations Map I-2185, scale 1:500,000.
Cannon, W.F., Kress, T.H., Sutphin, D.M., Morey, G.B., Meints, Joyce, and Barber-Delach, Robert, 1997, Digital Geologic Map and mineral deposits of the Lake Superior Region, Minnesota, Wisconsin, Michigan: USGS Open-File Report 97-455 (version 3, Nov. 1999).
|Counties||Gogebic - Ontonagon|