Unit Name: Mason River Formation
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Currently in use
Age Interval: Late Cretaceous (99.6 - 65.5 ma)
Age Justification: Radiolarians, sponge spicules, palynomorphs and vertebrates.
Province/Territory: Northwest Territories
Originator: Yorath et al., 1975.
Type Locality:
The composite type section is along the lower Horton River at 69 deg 28'N, 126 deg 59'W and 69 deg 58'N, 127 deg 04'W.
Distribution:
About 183 m (600 ft). The Mason River Fm is well exposed in the Franklin Bay area and the southernmost part of the Malloch Hill area.
Lithology:
It consists of three informal members here listed in ascending order: lower member, 117.3 m (385 ft) of pale grey weathering soft, blocky, to moderately fissile shale with thin beds of jarosite in the lower 18 m (60 ft) and in the upper 15 m (50 ft) dark ferruginous carbonate concretions occur in the middle part of the member; middle member, about 30 m (100 ft) of medium to dark grey, and pale grey shale with minor interbeds of jarosite; and the upper member, 32 m (105 ft) medium to dark grey brown ferruginous shale that grades upwards into pale grey sandy shale.
Relationship:
The Mason River Fm gradationally overlies the Smoking Hills Fm and is disconformably overlain by the Beaufort? Fm. This formation probably correlates with the "Shale member" of the Kanguk Fm (Plauchut and Jutard, 1976). Southwestward, it grades into the Mason River Fm.
Other Citations:
Doerenkamp et al., 1976; Plauchut and Jutard, 1976; Yorath and Balkwill, 1970; Yorath et al., 1975.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 2, Yukon Territory and District of Mackenzie; L.V. Hills, E.V. Sangster and L.B. Suneby (editor)
Contributor: L.V. Hills; C.J. Yorath
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 29 Apr 2003