A Revision of Stratigraphic Nomenclature for Middle Precambrian Rocks in Northern Michigan

Abstract

The name Marquette Range Supergroup is proposed to supplant the term Animikie Series for middle Precambrian strata of the Northern Peninsula of Michigan and adjacent areas of Wisconsin. The Marquette Range Supergroup consists of the Chocolay, Menominee, Baraga, and Paint River Groups, as defined in previous literature. We feel that this new name to apply to Northern Peninsula rock units is appropriate, as continued investigations have failed to show unequivocal correlation between middle Precambrian rocks of Michigan and the Huronian Supergroup of Ontario. Although the equivalence of the Animikie Group in Ontario and Minnesota with parts of the Michigan rocks is likely, the Stratigraphic complexity of the Michigan sequence requires supergroup rank. The inherent confusion of an Animikie Group in Ontario and Minnesota, and an Animikie Supergroup in Michigan, makes a local name such as Marquette Range Supergroup preferable to Animikie for the middle Precambrian rocks of Michigan.