Baseline stratigraphy of the Lisburne Group

Michelle M. McGee amd Michael T. Whalen, Geophysical Institute and Department
of Geology and Geophysics, University of Alaska, Fairbanks, Alaska 99775-5780

Significant progress has been made on establishing the baseline stratigraphy of the Lisburne Group, Porcupine Lake area, Philip Smith Mountains. Six partial sections in the Wachsmuth and Alapah Limestone were the focus of the 2000 field season. The
Wachsmuth is poorly exposed and appears to be gradational with the underlying Kayak Shale and overlying lower Alapah Limestone. The lower Alapah is resistant and displays dark (chert) and light (limestone) banding. The middle Alapah is recessive and the upper Alapah is resistant and lithologically similar to the Wahoo Limestone in the north. Cycles in the Alapah, overall, shallow up from mudstones or wackestones to packstones, grainstones, or rudstones. Several parasequences were identified in the upper middle Alapah and upper Alapah. These packages are based on weathering profiles and may have an impact on the mechanical stratigraphy. Very little to no Wahoo was identified in the field areas. The thinness of the Wahoo maybe due to non-deposition or removal by erosion or tectonics.

The data collected will be used to identify depositional cycles and parasequences and provide criteria for correlations between Prudhoe Bay cores and Brooks Range outcrops. Subsurface and surface data will delineate package geometries, lateral changes of lithology and reservoir characteristics, and paleogeography across the broad carbonate platform. Seismic scale cross sections will eventually be constructed that will aid in sequence stratigraphic interpretations and delineation of major reservoir units.