Field notes on the Upper Devonian Imperial Formation (NTS map sheet 106L), Tetlit Creek, east Richardson Mountains, Yukon
Description
Although the Upper Devonian Imperial Formation is widespread across northern Yukon and Northwest Territories, its geology is poorly understood in northern Yukon. The Imperial Formation is well exposed in outcrop along the eastern flank of the Richardson Mountains, notably on Tetlit Creek and Trail River (NTS map sheet 106L). During the summer of 2008, detailed partial stratigraphic sections were measured on Tetlit Creek to record lithologic variation within the formation. In addition, samples were collected to establish the age of the strata and its source rock potential by means of palynological, geochemical and vitrinite reflectance analyses.
In the east Richardson Mountains, Imperial Formation strata can be informally subdivided into two parts. The lower is predominantly mudstone and siltstone while the upper part comprises sandstone and fine-grained siliciclastic rocks. Palynological analyses for this region have established that the Imperial Formation is late Frasnian to Famennian in age. Accompanying thermal alteration indices (T.A.I.), as well as vitrinite reflectance data, suggest that the strata are overmature with respect to hydrocarbon generation. Based on Rock Eval/TOC results from surface, most of the organic matter present within the strata are not favourable for source rock potential.