Porcupine Volcanics (WIYpv;0)

State	Wisconsin
Name	Porcupine Volcanics
Geologic age	Middle Proterozoic
Lithologic constituents	Major Igneous > Volcanic > Mafic-volcanic > Andesite (Flow)Generally dark-gray basalt, andesite, and felsite flows and subordinate interflow sedimentary rocks Minor Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)Generally dark-gray basalt, andesite, and felsite flows and subordinate interflow sedimentary rocks Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow)rhyolite Incidental Sedimentary > Clastic > Mixed-clastic > Sandstone-mudstoneGenerally 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 This has been replaced by the naming the unit, the Porcupine Volcanics, and using the symbol "Ypv" (Cannon and others, 1997). Unit description here is from the unit description of "Yu" on Sims (1992)
References	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), scale 1:500,000. https://pubs.er.usgs.gov/publication/ofr97455 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. https://pubs.er.usgs.gov/publication/i2185
NGMDB product	NGMDB product page for 10177 NGMDB product page for 49339
Counties	Iron

State

Name

Porcupine Volcanics

Geologic age

Middle Proterozoic

Lithologic constituents

Major

Igneous > Volcanic > Mafic-volcanic > Andesite (Flow)Generally dark-gray basalt, andesite, and felsite flows and subordinate interflow sedimentary rocks

Minor

Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)Generally dark-gray basalt, andesite, and felsite flows and subordinate interflow sedimentary rocks

Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow)rhyolite

Incidental

Sedimentary > Clastic > Mixed-clastic > Sandstone-mudstoneGenerally 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" (Cannon and others, 1997). Unit description here is from the unit description of "Yu" on Sims (1992)

References

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), scale 1:500,000.

https://pubs.er.usgs.gov/publication/ofr97455

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.

https://pubs.er.usgs.gov/publication/i2185

NGMDB product

NGMDB product page for 10177

NGMDB product page for 49339

Counties

Iron