The terrestrial trace fossil Taenidium in the McMurray-Wabiskaw transition of north-central Alberta and its application to sequence stratigraphy

Abstract

During the growth of the Rocky Mountains in the Cretaceous, there was a major sea level rise event that flooded valleys and land that had been continental for millions of years prior. The Albian Wabiskaw Member of the Clearwater Formation represents the initial flooding of the Boreal Sea across Alberta. Examination of trace fossil assemblages, and sedimentology, in three subsurface core samples from the McMurray-Wabiskaw transition in north-central Alberta has shown that terrestrial trace fossils (Taenidium) are present. A north-south cross-section was constructed showing fully marine trace fossil assemblages to the north and terrestrial trace fossils to the south. The cross-cutting nature, lack of marine trace fossils, and associated presence of rootlets, coal, and synaeresis cracks are the major lines of evidence to support the terrestrial trace fossil interpretation. Other examples in the Cretaceous of Alberta (e.g, Cardium Formation; Belly River Group) seem to suggest that terrestrial trace fossils are associated with sequence boundaries before lowstand, or after forced regressive conditions. The recognition of terrestrial trace fossils could serve as a potential sequence stratigraphic tool for other rock units that contain terrestrial traces, including those as old as the latest Silurian (more than 400 million years ago).

* Indicates faculty mentor.