Type Locality:

The type measured traverse of the Elmer Creek Formation is Section 18 (Fig. 11, 23-25; Cecile, 1997a) which was measured in a creek bottom northwest of Algae Lake, in NTS 105-O/15. The traverse starts at UTM co-ordinates 405950 E, 7075750 N, and ends at 404600 E, 7075100 N, Zone 9. Without attempting to accommodate thinning or thickening due to strain, the total thickness of composite type section is 110 m. Because the traverse mostly crosses fold limbs, this thickness is considered a minimum, and true thickness may be 20 per cent to 100 per cent greater (Cecile, 2000).

Distribution:

Palinspastic restoration of the Elmer Creek unit extends its distribution much farther west, beyond the Niddery map area and across the width of the Selwyn Basin. This puts the western limits of this unit well into the realm of transitional to, and/or, possibly true, oceanic crust. (Cecile, 2000).

Locality Data:

Thickness(m): Minimum 110.

Lithology:

The Elmer Creek Formation can be divided into mappable upper and lower members in the study area. The lower member consists of a lower succession of pale green and drab grey siliceous argillite and argillaceous chert, with minor thin beds of brown dolostone. In the measured traverse dolostones in this position were observed as either a single bed or multiple beds. The association of the dolostone(s) with siliceous argillite, and the rare repetition of dolostone in the traverse, suggests that they are likely from a single or a similar stratigraphic position, and so one zone of dolostone is assumed. The upper part of the lower member is a 30 m thick, resistant, drab grey weathering succession of bioturbated chert (Cecile, 2000, Fig. 26) and massive chert. The upper member of the Elmer Creek Formation is a very distinctive succession of whitish weathering, dark black, siliceous shale and chert, usually containing biserial graptolites of Middle and Late Ordovician age. In the type composite section it is 17 m thick.

Fossils:

Graptolites and conodonts

Paleo Environment:

marine, offshore

Relationship:

Parent: Road River Group. The Elmer Creek Formation is in distinct conformable contact with the Gull Lake Formation. The contact is defined where very siliceous argillite or chert dominate the succession and can usually be placed to within a few metres. The contact between the upper and lower members is sharp and distinct and is marked as a change from drab grey siliceous argillite on top of massive chert, to black weathering siliceous shale or chert. The Elmer Creek Formation is correlative with the Duo Lake Formation, and is likely a widespread unit in the Selwyn Basin to the west and southwest. Outcrops of chert typical of the lower Elmer Creek member have been observed in the parts of the Sheldon, Tay and Lansing map areas that adjoin the Niddery Lake map area. In these three map areas, cherts of this description are included in the map unit OSr of Gordey and Irwin (1987), and OEC of Roots et al. (1995a, b). Similar strata are reported from the southern Ogilvie Mountains (map units OSDR3,4 of Abbott and Roots, 1993) and from the Barn and British Mountains (Oc unit of Cecile, 1988; Cecile and Lane, 1991; and Oac unit of Lane and Cecile, 1989).

Remark:

This unit is interpreted as a very deep-water deposit. The dominance of chert over shale and low carbonate content indicates slow deposition, mostly below the carbonate compensation depth. Carbonate, present in part of the unit, may reflect a relative drop in the level of carbonate compensation depth, or the carbonate may be of detrital origin (Cecile, 2000).

References:

Abbott, J.G. and Roots, C.F., 1993. Geological map of Two Beaver Lake map area, Ogilvie Mountains, Yukon (116 A/11); Indian and Northern Affairs Canada, Exploration and Geological Services Division, Yukon Region, Open File 1993-8 (G).

Cecile, M.P. and Lane, L.S., 1991. Geology of the Barn Uplift; Geological Survey of Canada, Open File 2342.

Cecile, M.P., 1984c. Geology of southwestern and central Niddery Lake map area (115-O/4,5,6,11); Geological Survey of Canada, Open File 1118.

Cecile, M.P., 1988. Corridor traverse through Barn Mountains, northernmost Yukon; in, Current Research, Part D; Geological Survey of Canada, Paper 88-1D, pp. 99-103.

Cecile, M.P., 1997a. Geology of the Thor Hills map area (NTS 105-O/15); Geological Survey of Canada, Map 1899A, Scale: 1:50 000.

Cecile, M.P., 2000. Geology of the northeastern Niddery Lake map area, east-central Yukon and adjacent Northwest Territories; Geological Survey of Canada, Bulletin 553, 120 p.

Gordey, S.P. and Irwin, S.E.B., 1987. Geology, Sheldon Lake and Tay River map areas, Yukon Territory; Geological Survey of Canada, Map 19-1987 (3 sheets), Scale 1:250 000.

Lane, L.S. and Cecile, M.P., 1989. Stratigraphy and structure of the Neruokpuk Formation, northern Yukon; in, Current Research, Part G; Geological Survey of Canada, Paper 89-1G, pp. 57-62.

Roots, C.F., Abbott, J.G., Cecile, M.P., Gordey, S.P., and Orchard, M.J., 1995b. New stratigraphy and structures in eastern Lansing map area, central Yukon Territory; in, Current Reseach, Part A; Geological Survey of Canada, Paper 1995A, p. 141-148.

Roots, C.F., Abbott, J.G., Cecile, M.P., and Gordey, S.P., 1995a. Bedrock geology of Lansing Range map area (105N) east half, Hess Mountains, Yukon; Indian and Northern Affairs Canada, Exploration and Geological Services Division, Yukon Region, Open File 1995-7 (G).