The Mississippian Souris Valley Beds of South-Central Saskatchewan (Northern Williston Basin): Potential New Exploration Targets in a Mature Basin

Erik H. Nickel
Saskatchewan Industry and Resources, Regina, SK

The Saskatchewan Geological Survey has completed mapping of Devonian and Mississippian strata of a large portion of south central Saskatchewan, in part to industry requests to have more research undertaken on the area. This study has produced a full suite of updated structure, isopach and subcrop maps of the main Devonian and Mississippian units, as well as more detailed investigations into some of the Mississippian units in the area. These investigations have provided new insights into depositional characteristics of the lower Mississipian units which have lead to some potential new exploration targets in this mature basin.

The Mississippian (Kinderhookian) Souris Valley Beds (Lodgepole Formation) are a thick package of platform and basinal carbonates that overlie the deeper-water clastics of the Bakken Formation. Significant in the Souris Valley Beds is the presence of Waulsortian-type mounds. These “mud mounds” are oil bearing elsewhere in the Williston Basin, however very few have been drilled or tested in the south-central project area. Depositional facies and paleogeographical position of these mud mounds were interpreted from a detailed stratigraphic analysis of the Souris Valley Beds. Paleogeography related to uplift of the Roncott Platform may have controlled the distribution of facies in the Souris Valley. The movement of the Roncott platform may have been influenced by tectonism related both to basement movements, and the variable dissolution of the underlying Devonian Prairie Evaporite. Using these findings, it is then possible to develop criteria that can lead to the discovery of more Waulsortian-type bioherms.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005