Open File Report 2012-20

Open File Report 2012-20

OFR 2012-20

Outcrops of the La Loche, Contact Rapids, and Keg River Formations (Devonian) on the Clearwater River: Alberta (NTS 74D/9) and Saskatchewan (NTS 74C/12)

Author(s) Schneider, C.L. Grobe, M. Hein, F.J. Date 2013-04-10

The Middle Devonian Elk Point Group outcrops along the Clearwater River near the Alberta-Saskatchewan border. In this area, sedimentary rocks of the Elk Point Group rest directly on crystalline Precambrian basement rocks.

In this report, we describe outcrops of the La Loche, Contact Rapids, and Keg River formations visited during the 2010 field season. At a previously undescribed outcrop at Contact Rapids located on the Clearwater River in Saskatchewan, we observed the nonconformable contact between a paleotopographic high in the Precambrian basement and the La Loche Formation. In addition, we describe in this report the conformable contact between the Contact Rapids and Keg River formations, which had previously been unobserved at the described locality. At Whitemud Falls on the Clearwater River in Alberta, we observed the contact between the La Loche and Keg River formations where the intervening Contact Rapids Formation is absent. This contact is evidence that the outcrop is close to an unexposed paleotopographic basement high that remained exposed during the early stages of Keg River Formation carbonate deposition.