Porcupine Volcanics (MIYpv;0)

State	Michigan
Name	Porcupine Volcanics
Geologic age	Middle Proterozoic
Lithologic constituents	Major 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 Minor Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow) Incidental 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 This has been replaced by the naming the unit, the Porcupine Volcanics, and using the symbol "Ypv" as was done in the digital map of Cannon et al.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)
References	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 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). https://pubs.er.usgs.gov/publication/ofr97455
NGMDB product	NGMDB product page for 10177 NGMDB product page for 71888 NGMDB product page for 71887
Counties	Gogebic - Ontonagon

State

Name

Porcupine Volcanics

Geologic age

Middle Proterozoic

Lithologic constituents

Major

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

Minor

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

Incidental

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)

References

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

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).

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

NGMDB product

NGMDB product page for 10177

NGMDB product page for 71888

NGMDB product page for 71887

Counties

Gogebic - Ontonagon