Peat-forming history of the ancestral Souris mire (Palaeocene), Ravenscrag Formation, southern Saskatchewan, Canada

Abstract

Analysis of the Palaeocene Souris Lignite (northern Williston Basin) using coal petrology and palynology reveals the existence of seven different mire types forming six cycles of varying thickness and composition. The order of mire types within the individual cycles allows an idealized mire type succession to be defined. The principle factor driving the idealized mire type succession is decreasing water depth within the peat-forming environment (terrestrialization), which leads to an increase in species diversity and a change in floral character from ferns→ angiosperms→ gymnosperms. Increases in water depth are the primary agent responsible for the termination of individual cycles in the ancestral Souris mire. Changes in nutrient status of the mire may also promote major changes in the floral assemblage, contributing to cycle termination. Comparison of densinite:ulminite ratios for the central part of the Souris seam shows an overall decrease in the degree of humification south-westward, indicating increased subsidence towards the Williston Basin centre, where seam partings are more common. Fern-rich mire types dominate throughout most of the sampled part of the Souris seam and such mires have been interpreted as representing transitional stages in both modern and Tertiary peat-forming environments. Previous analysis of other parts of the Souris seam has revealed areas dominated by Taxodium forest mires, representing more stable environments. The co-existence of transitional and stable environments suggests that the ancestral Souris mire may have been deposited during the onset of the closing stages of Palaeocene peat formation in the northern part of the Williston Basin.

A multi-proxy study of changing environmental conditions in a Younger Dryas sequence in southwestern Manitoba, Canada, and evidence for an extraterrestrial event

“…2). Pollen and spores from these deposits are described in Frank (1999) and Frank and Bend (2004), and our reworked assemblage in the lower Lake Hind sediments corresponds closely to those from the top of the Souris Lignite (Ravenscrag Fm). This can be seen in the dominance of Taxodiaceaepollenites , triporate angiosperm pollen (e.g., our “cf.…”

“…Corylus ” type) and various conifer and fern pollen types (fig. 4 in Frank and Bend, 2004). The high percentage of Paleocene palynomorphs below −33 cm coincides with a high rate of sedimentation and a greater abundance of charcoal and coal particles in the lower part of the section (Fig.…”

Insights into the rare earth element potential of coal combustion by-products from western Canada

“…These power stations burn lignite coal from the Paleocene Ravenscrag Formation of the Williston sub-basin which is stratigraphically equivalent to the Fort Union Formation of the Powder River Basin. 35 Samples from Alberta were provided for a single generating station with two generators, a lower temperature boiler (AB12) and a higher temperature boiler (AB3) which burn sub-bituminous coal from the upper Cretaceous-Paleocene Scollard Formation of the Alberta sub-basin. In total, five sets of CCBs were analyzed in this study.…”

A paleoclimatic and paleoatmospheric record from peatlands accumulating during the Cretaceous-Paleogene boundary event, Western Interior Basin, Canada

“…Published petrological studies of Cretaceous-Paleogene boundary coals (i.e., Sweet and Cameron, 1991;Belcher et al, 2003) do not tabulate coal composition, but on a mineralfree basis, the bulk composition of the Cretaceous-Paleogene boundary coals in this study is enriched in inertinite and liptinite relative to slightly younger Paleocene coals from the Frenchman Formation in the same study area Potter et al, 1991;Frank and Bend, 2004) as well as relative to Mesozoic to Cenozoic coals and Quaternary peats more generally (Diessel, 2010;Glasspool and Scott, 2010). This suggests that the frequency of wildfires in the interval bracketing the CretaceousPaleogene boundary was relatively high, superficially supporting the hypothesis that bolide impact at the Cretaceous-Paleogene boundary would have ignited regional-to-global-scale wildfires (Melosh et al, 1990;Woolbach et al, 1990;Morgan et al, 2013).…”