Gneiss and amphibolite

Interlayered quartzofeldspathic gneiss and amphibolite in Marenisco, Mich., area and northwestern Wisconsin. Protoliths are bimodal intermediate and mafic volcanic rocks (Sims and others, 1984).
State Wisconsin
Name Gneiss and amphibolite
Geologic age Late Archean
Lithologic constituents
Major
Metamorphic > Amphibolite
Metamorphic > Gneiss
Comments Continental margin assemblage (north of Niagara Fault). Sims and others, 1984, Geology, geochemistry, and age of Archean and Early Proterozoic rocks in the Marenisco-Watersmeet area, northern Michigan: U.S. Geological Survey Professional Paper 1292-A,. p. A1-A41.
References
NGMDB product
Counties Ashland - Bayfield - Iron - Sawyer - Vilas