Unit Name: Fermeuse Formation
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Currently in use
Age Interval: Proterozoic III (900 - 541 ma)
Age Justification: The age of the formation is inferred from its stratigraphic position. The Fermeuse contains some Vendian (late Proterozoic III) microfossils (Hofmann et al., 1979).
Province/Territory: Newfoundland & Labrador
Originator: Williams and King, 1979.
Type Locality:
Cliff section from about 200 m to 2 km west of Bear Cove Head, southeast Fermeuse Harbour, Trepassey area, southern Avalon Peninsula southeastern Newfoundland (NTS 1 K/15). A reference section occurs between Middle Cove and Outer Cove, north of St. John's.
Distribution:
The Formation is about 300 m thick at St. John's, gradually increasing to 1,400 m, south of Fermeuse Harbour (NTS 1 N/10). In the type locality of the St. John's Group, the Fermeuse Formation is incompletely exposed in the Rennie's and Virginia rivers (NTS 1 N/10), bounded by Prince Phillip Parkway to the west and Duckworth Street to the east in St. John's. It is the youngest exposed formation in the St. Shotts (NTS 1 K/12), Biscay Bay, and Cape Race (NTS 1 K/11) synclines of the Trepassey map-area. The lower unit of the Proterozoic III Carbonear Formation (Hutchinson, 1953), on the western side of Conception Bay (NTS 1 N/11), is lithologically comparable with the Fermeuse Formation (King, 1980).
Lithology:
At the base of the Formation are thinly bedded light grey shales that commonly display large-scale slump folds. Its upper part consists of dark grey shale with thin lenticular interbeds of buff weathering sandstones with some ripple lamination. Circular structures on bedding surfaces, from 1 to 10 cm diameter, include the trace fossil Aspidella terranovica (Billings, 1872). These occur toward the top of the formation with the best examples at Clear Cove on the north side of Fermeuse Harbour (NTS 1 K/15), Ferryland (NTS 1 N/2) and Prescott Street, St. John's (NTS 1 N/10). The Fer-meuse Formation forms the dominant lithology of the St. John's Group.
Relationship:
The Fermeuse Formation conformably and gradationally (50 m thick zone) overlies the Proterozoic III Trepassey Formation. It is conformably overlain by the Proterozoic III Renews Head Formation, the gradational zone being about 100 m thick. King (1980) showed that the Carbonear Formation of the Hodgewater Group is divisible into three units, which can be correlated with those in the St. John's Group of Williams and King (1979). The St. John's Group includes, in ascending order, the Trepassey, Fermeuse, and Renews Head formations.
History:
Rocks of the Fermeuse Formation formed the major lithic component of the 'St. John's Slate' (Jukes, 1843), 'Aspidella Slates' (Murray and Howley, 1881a, 1881b), 'Momable Slate' (Walcott, 1899), and the St. John's Formation (Rose, 1952). The Carbonear Formation (Hutchinson, 1953) was originally described as 'St. John's Slate' (Jukes, 1843) and the 'Aspidella Slates', (Murray and Howley, 1881a, 1881b). King (1980, 1982, 1984) correlated the Fermeuse Formation with the lower unnamed division of the Carbonear Formation. King (pers. comm.) recommended that the name Fermeuse Formation be applied to the lower division and that the name, 'St. John's Group' replace 'Carbonear Formation.'
Other Citations:
Billings, 1872; Hofmann et al., 1979; Hutchinson, 1953; Jukes, 1843; King A.F., 1980, 1982, 1984; Murray and Howley, 1881a, 1881b; Rose, 1952; Walcott, 1899; Williams and King, 1979.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 6, Atlantic Canada; G.L. Williams, L.R. Fyffe, R.J. Wardle, S.P. Colman-Sadd, Boehner, R.C. (editor)
Contributor: A.F. King
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 29 Apr 2003