Biotite schist

Metamorphosed graywacke in poorly exposed areas in northwestern Wisconsin. Sample at one locality (near Blockhouse Lake, 10 km northeast of Park Falls, T. 40 N., R. 1 E.) has a U-Pb zircon age of 1852 +/- 6 Ma (Sims and others, 1985b)
State Wisconsin
Name Biotite schist
Geologic age Early Proterozoic
Lithologic constituents
Major
Metamorphic > Schist > Mica-schist > Biotite-schistMetamorphosed graywacke in poorly exposed areas in northwestern Wisconsin.
Comments Continental margin assemblage (north of Niagara Fault). Sims and others, 1985b, Geology and geochronology of granitoid and metamorphic rocks of Late Archean age in northwestern Wisconsin: U.S. Geological Survey Professional Paper 1292-C, 17 p.
References
NGMDB product
Counties Ashland - Iron - Price - Sawyer - Vilas