Early Permian Climate Change in the Sverdrup Basin, Canadian Arctic: Characterizing Climatic Cooling Through Carbonate Facies Analysis and Conodont Biostratigraphy
Michael L. Wamsteeker
Department of Geosciences, University of Calgary Calgary, Alberta, Canada; [email protected]
The Sverdrup Basin of Nunavut, Arctic Canada is one of the few North American basins with significant frontier exploration potential. Drilling during the 1960’s to 1980’s resulted in the discovery of 14 TCF of gas and a significant quantity of oil. However, creaming curve analysis has revealed that the popular Mesozoic-anticlinal structure play may have matured, with possibly little future upside. Several prospective play concepts lie in Late Paleozoic (Mississipian-Permian) carbonate strata of the Sverdrup Basin. However, reservoir quality of these carbonates show wide variation. Best porosity and permeability is developed in Early Permian (Sakmarian) or older nearshore facies, and is mostly created by warm-water, early diagenetic processes (eg. dolomitization, dissolution associated with subaerial exposure).
Ocean temperature and ambient climate of the Sverdrup Basin cooled during the Early Permian, transitioning from warm-water or tropical-like conditions to subtropical sometime during the Sakmarian. Cooling is recognized through monitoring changes in fossils, lithology and sedimentary textures within shallow marine strata, which shift from a photozoan to heterozoan allochem association. This cooling coincides with a significant reduction of early diagenetic porosity and permeability within aforementioned prospective reservoir facies.
This study aims to characterize cooling through time and water depth within the Asselian-Sakmarian carbonates near Elmerson Peninsula, Ellesmere Island. Conodont biostratigraphy coupled with carbonate facies analysis will be used to reconstruct the Asselian-Sakmarian depositional environment, tracking the progress of oceanic cooling in paleo-water depth and time. Characterization of cooling will more precisely determine the age and stratigraphic position at which prospective warm-water, diagenetic reservoir disappears.
AAPG Search and Discovery Article #90083 © 2008 AAPG Foundation Grants in Aid