Preliminary
Investigation of the Carboniferous Lisburne Group, Nanushuk
River Region, Central
Brooks Range
Jesse Garnett White, University of Alaska Fairbanks, Department
of Geology and Geophysics, Natural Sciences Building, 900 Yukon
Drive
, P.O. Box
755780, Fairbanks, AK 99775-5780, [email protected]
The Carboniferous Lisburne Group, a
succession of carbonate rocks, has been identified in the Brooks
Range Endicott Mountains allochthon, parautochthonous rocks in the
northeastern Brooks Range, and in the North Slope
subsurface. The Lisburne Group was the
original
reservoir
exploration target in the Lisburne field at Prudhoe Bay. Its
importance as both a potential subsurface source and
reservoir
rock warrants
further investigation into the carbonate facies, lithologies, and conodont
microfacies for continued correlation with other stratigraphic sections and
well data across the Brooks Range and North
Slope of Alaska. The Lisburne Group is a
potential
reservoir
target in the National Petroleum Reserve, Alaska and in the Arctic National Wildlife
Refuge (ANWR) 1002 Area. The variation
in carbonate depositional environments, stratigraphy, facies, and long distances
between the western and eastern Brooks Range
make correlation of units within the Lisburne difficult.
A total of 1271 meters of Kayak Shale and Lisburne Group
outcrop were measured, sampled, and described in the central Brooks Range near
the headwaters of the Nanushuk
River to gather high
resolution stratigraphic data to better interpret depositional environments and
improve stratigraphic correlations with application of conodont
biostratigraphy. The Nanushuk River
section (Alapah Mountain Section of Armstrong and Mamet, 1978) records marginal
marine depositional environments in the uppermost Kayak shale. Carbonate ramp sedimentation began on a
marginal marine platform, followed by gradational slope and deep water starved
basin-euxinic sediments, followed by continued open marine sedimentation
(Armstrong and Mamet, 1978). The section
is overlain by the Permian Etivluk Group, Siksikpuk Formation.