McGee, M.M., 2004, Carboniferous Lisburne Group carbonates of the Porcupine Lake Valley: Implications for surface to subsurface sequence stratigraphy, paleogeography, and paleoclimatology: University of Alaska Fairbanks, Ph.D. dissertation, 454 p., illust., maps.
This study utilizes high-resolution stratigraphy and sequence stratigraphy to document the response of the Carboniferous Lisburne Group carbonate platform during a change from greenhouse to icehouse conditions. The Lisburne Group in northern Alaska represents a laterally extensive carbonate ramp deposited on a passive continental margin during a greenhouse-to-icehouse transition. The Lisburne Group is subdivided into the Mississippian Wachsmuth and Alapah Limestones and Mississippian to Pennsylvanian Wahoo Limestone. I have identified six depositional sequences and corresponding systems tracts in the Lisburne Group based on bounding surfaces, cycle stacking patterns, and lateral lithofacies relationships. The Wachsmuth Limestone (Sequences I and II) comprises relatively thick cycles that have a 'layer cake' stacking pattern that records minor migration of facies. Cycles in the uppermost Wachsmuth Limestone and the Alapah Limestone (Sequences III and IV) are thick, less 'layer cake'-like, have deep-water tongues at the base, and record significant migration of facies. Cycles in the uppermost Alapah Limestone and the Wahoo Limestone (Sequences V and VI) are thin, juxtapose deep-water over shallow-water facies, and record significant migration of facies. An unconformity marked by paleosols and karst features has been documented near the Mississippian-Pennsylvanian boundary in the Wahoo Limestone. I interpret the distinct change in cycle stacking patterns between the Mississippian and Pennsylvanian Lisburne Group to be related to changes in Paleoclimate. I interpret Sequences I through IV to be deposited during a greenhouse and transitional climate, whereas, Sequences V and VI were deposited during an icehouse climate.
Theses and Dissertations
