T137 Lacustrine Basin Analysis and Petroleum Systems: Ancient Case Studies, Modern Analogs, New Frontiers (Posters)
Monday, 28 October 2013
9:00 AM - 6:30 PM
Hall D
DEPOSITIONAL ENVIRONMENT OF THE WANAKAH FORMATION IN THE WESTERN COLORADO REGION: AN ANALOG STUDY FOR LACUSTRINE PETROLEUM SYSTEMS
Paper number: T137-7
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM
Authors
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Sally Potter-McIntyreSouthern Illinois University, Carbondale, IL
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Marisa BoraasColorado State University, Fort Collins, CO
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Andres AslanColorado Mesa University, Grand Junction, CO
Abstract
The Jurassic Wanakah Formation is exposed in western Colorado and functions as a seal that overlies the permeable Entrada Sandstone. Previous studies assign either a marine or lacustrine depositional environment to the unit; this study tests the hypothesis of a hypersaline lake origin. Petrography, QEMSCAN, XRD, whole rock analysis and stable isotopes are used to evaluate the petrography, mineralogy, and geochemistry to document lateral lithofacies variability and construct a regional stratigraphic cross-section. Sedimentary and petrophysical properties within the Wanakah Formation in western Colorado suggest a hypersaline lake system that records subaqueous deposition, meters-thick horizons of gypsum precipitation, saturated and exposed paleosol development and fluvial and shoreline sandstones. Lateral variability on an outcrop-scale within the Wanakah Formation suggests that any petroleum system that includes lacustrine units must be evaluated on a fine scale to ensure a comprehensive picture of the system.