Type Locality:

The type section for the Tsichu Group and most of its formations is on the southwest limb of the Stew Syncline, and consists of three parts. The first part, for the Hawthorne Creek and Hertiage Trail formations, has the following UTM co-ordinates: base at 449100 E, 7057450 N, top at 449400 E, 7057800 N (2093 peak of map; NTS 105-O/09) (Cecile, 2000).

Distribution:

The Hawthorne Creek Formation outcrops in the southeast hinge zone of the Stew Syncline (see maps of Cecile, 1997b) and continues into the adjacent Sekwi map area to the southeast (Cecile, 2000).

Lithology:

The type Hawthorne Creek Formation consists of two units: a lower, 200 m thick succession of black shale with minor quartzite and siltstone, and an upper, 130 m thick succession of black calcareous shale with medium to thick beds of yellow weathering limestone (Cecile, 2000).

Relationship:

The Hawthorne Creek Formation is part of the Tsichu Group. The type Hawthorne Creek Formation rests conformably on the Thor Hills Formation (Earn Group). The two units are distinguished on the basis of their associated sandstone composition. The Thor Hills Formation contains chert lithic sandstone and chert pebble conglomerate, and units of siliceous shale, and the Hawthorne Creek Formation contains quartz sandstones in its basal unit and limestones in its upper unit. The Thor Hills formation is not well exposed at this section. The type Heritage Trail Formation (Tsichu Group) has a sharp but apparently conformable contact with the underlying Hawthorne Creek Formation. In the North Macmillian Fold Belt, along the southern part of the Niddery Lake map area the Hawthorne Creek Formation is considered to be correlative with map unit DMsh2a of Cecile and Abbott (1992). This map unit and the Hawthorne Creek Formation are apparently homotaxial. The DMsh2a map unit is 200 to 400 m thick and is characterized by the presence of 30 to 50 per cent thin beds of laminated to crosslaminated quartzite. At the type section (North Macmillan Fold Belt) of the Caribou Pass Formation (Tsichu Group), the Hawthorne Creek Formation is missing, either through facies transition or erosion. In the adjoining Sekwi map area it is directly correlative with the top of Unit 26 of Blusson (1971). Gordey and Anderson (1993) recognized Prevost Formation in southeastern Niddery Lake map area. However the unit they designated as Prevost? is identical to the Hawthorne Creek Formation, and included with the Tsichu Group because it contains quartzite and limestone (Cecile, 2000).

History:

The Hawthorne Creek Formation is named after Hawthorne Creek north of the type section (Cecile, 2000).

Remark:

The Hawthorne and the Keele Creek formations are interpreted as deeper water deposits that accumulated on the peripheries of shallow-water units (Cecile, 2000).

References:

Blusson, S.L., 1971. Sekwi Mountain map-area, Yukon Territory and District of Mackenzie (105 P); Geological Survey of Canada, Paper 71-22, 17 p. + "A" Series Map 1333A, Geology, Sekwi Mountain, Northwest Territories - Yukon Territories; Scale: 1:250 000.

Cecile, M.P., 1997b. Geology of NTS 105-O/09 and northern part of Keele Peak map area (NTS 105-O/08); Geological Survey of Canada, Map 1902A. 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.

Cecile, M.P., and Abbott, J.G., 1992. Geology of the Niddery Lake map area (NTS 105-O) at 1:250 000; Geological Survey of Canada, Open File 2465, 1 geological map (Scale 1:250 000) + 1 geological legend.

Gordey, S.P. and Anderson, R.G., 1993. Evolution of the northern Cordilleran miogeocline, Nahanni map area (105I), Yukon Territory and District of Mackenzie; Geological Survey of Canada, Memoir 428, 214 p.