Chengwatana Volcanic Group (WIYcv;0)

State	Wisconsin
Name	Chengwatana Volcanic Group
Geologic age	Middle Proterozoic
Original map label	Ycv
Comments	This group has U-Pb zircon ages ranging from about 1094.6 +/- 2.1 Ma from a rhyolite near Lake Nelson, WI (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) to 1100-1102 +/- 5 Ma elsewhere in the unit (G. Garrels, Univ. of Arizona, unpublished data, 2000; M. Schmidt, MIT, unpublished data, 2000).
Primary rock type	basalt
Secondary rock type
Other rock types
Lithologic constituents	Major Igneous > Volcanic > Mafic-volcanic > Basalt (Flow) Minor Sedimentary > Clastic > Mixed-clastic (Bed) Igneous > Volcanic > Mafic-volcanic > Basalt (Pyroclastic, tuff)
Map references	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 [http://pubs.er.usgs.gov/publication/i2185]
Unit 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 G. Garrels, Univ. of Arizona, unpublished data, 2000 M. Schmidt, MIT, unpublished data, 2000
Geographic coverage	Bayfield - Burnett - Douglas - Polk - Sawyer - Washburn