Age Relationships and Stratigraphic Architecture of the Lea Park Formation and Equivalents, Southern Alberta and Saskatchewan, Western Canada Sedimentary Basin

Andrew J. Mumpy and Octavian Catuneanu
Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, Canada

The Campanian Lea Park Formation of the Western Canada Sedimentary Basin (WCSB) is a widespread marine shale unit present beneath the plains of Alberta and Saskatchewan. The upper Lea Park constitutes a previously unstudied potential shale gas play, and the lower Lea Park is comprised of the sandy Alderson Member, a prolific gas producer in the southern Alberta-Saskatchewan border region. Despite these facts, the internal stratigraphy of the interval is poorly understood and remains enigmatic for several reasons: 1) The detailed time relationships within Santonian-Campanian strata in the WCSB remain uncertain; 2) Previously documented regional unconformities in the interval remain unexplained; 3) A comprehensive sequence stratigraphic framework has not been developed for the interval in southern Alberta or Saskatchewan. Construction of a high-resolution time framework is feasible by integrating previously published micropaleontological and palynological data with new paleomagnetic data obtained from cores penetrating the Lea Park/Alderson interval. Bio- and magnetostratigraphic methodologies will help clarify age relationships and constrain the duration of stratigraphic hiatuses both within Canada and also within coeval stratigraphic units in Montana (Eagle and Claggett Formations), thereby facilitating regional correlations. Additionally, an extensive well log database allows for high resolution subsurface mapping of these units in 3-D across much of the study area, facilitating the development of a sequence stratigraphic framework. Correlations across flexural provinces of the WCSB may elucidate the relative contributions of tectonic subsidence mechanisms (i.e., flexural, dynamic, and basement components), which were the driving forces behind relative sea level fluctuations in the WCSB during Campanian time.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas