Unit Name: Portage Chute Formation
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Currently in use
Age Interval: Maysvillian - Richmondian (453 - 445.6 ma)
Age Justification: Biostratigraphy: Nelson (1963) assigned the parent Bad Cache Rapids Group to early Richmondian to Maysvillian.
Province/Territory: Manitoba; Nunavut
Originator: Nelson, 1963.
Type Locality:
The type section for the Portage Chute Formation is on the south side of Bad Cache Rapids (Nelson, 1963, locality 25272).
Distribution:
The formation is well exposed on the Nelson River from near Long Spruce Rapids to a short distance below Third Upper Limestone Rapids, a distance of almost 13 km (Nelson, 1963).
Locality Data:
Thickness(m): Typical 23.
Lithology:
The basal 1.2 m of the formation is a poorly fossiliferous calcareous quartz sandstone, which passes up conformably into 21.6 m of richly fosiliferous grey to buff weathering, light grey, microcrystalline, slightly dolomitic limestone (Nelson, 1963).
Fossils:
Corals, gastropods, cephalopods and brachiopods (Nelson, 1963).
Relationship:
The Portage Chute Formation of the Bad Cache Rapids Group rests unconformably on peneplaned Precambrian granitic rock, and is overlain by the Surprise Creek Formation (Nelson, 1963).
References:
Nelson, S.J., 1963. Ordovician paleontology of northern Hudson Bay Lowland; Geological Society of America, Memoir 90, 152 p.
Source: GSC file of geological names; T.E. Bolton and J. Dougherty (compiler)
Contributor: P.H. Davenport
Entry Reviewed: No
Name Set: Lithostratigraphic Lexicon
LastChange: 06 Nov 2007