Copper Harbor Conglomerate; Volcanic member

Basaltic to andesitic volcanic flows interbedded within the conglomerate and sandstone
State Michigan
Name Copper Harbor Conglomerate; Volcanic member
Geologic age Early Proterozoic
Lithologic constituents
Major
Igneous > Volcanic > Mafic-volcanic > Basaltic-andesite (Flow)Basaltic to andesitic volcanic flows
Comments Local usage calls these interbedded volcanic (andesitic) flows "Lake shore traps". A U-Pb zircon age for this unit in Michigan yields a date of 1087.2 +/- 1.6 Ma (Davis, D.W., and Paces, J.B., 1990, Time resolution of geologic events on the Keweenaw Peninsula and implications for development of the Midcontinent rift system: Earth and Planetary Science Letters, v. 97, p. 54-64.)
References

Davis, D.W., and Paces, J.B., 1990, Time resolution of geologic events on the Keweenaw Peninsula and implications for development of the Midcontinent rift system: Earth and Planetary Science Letters, v. 97, p. 54-64.

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
Counties Gogebic - Houghton - Keweenaw - Ontonagon