--> Distribution of Mesozoic Strata Under Lower Cretaceous Unconformity in Sadlerochit Mountains and Adjacent Coastal Plain, Northeastern Alaska, by J. S. Kelley and R. L. Detterman; #91024 (1989)

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Distribution of Mesozoic Strata Under Lower Cretaceous Unconformity in Sadlerochit Mountains and Adjacent Coastal Plain, Northeastern Alaska

J. S. Kelley, R. L. Detterman

New field data from the Sadlerochit Mountains in combination with published data from U.S. Geological Survey Bulletin 1778 provide a more detailed distribution of potential reservoirs and source beds and reveal evidence of structure under the Lower Cretaceous unconformity (LCU) in the Arctic National Wildlife Refuge (ANWR). Stratigraphic relations below the Marsh Creek, West Fork, and equivalent thrust sheets further define the distribution of Triassic and younger strata under the LCU. Defining data are from (1) reconstructions of the Weller and Itkilyariak thrust faults zones, (2) exposures on the south flank of the Sadlerochit Mountains, (3) outcrops and seismic data in the Niguanak Ridge area, and (4) wells west of ANWR.

Structural restoration with 30% maximum shortening reveals the possible limb and crest of a south-southeast-plunging anticline beneath the LCU. Although a north limb is not evident in ANWR, Bushnell, in 1981, suggested that Ellesmerian strata underlie the Beaufort Sea shelf. Our proposed truncation pattern suggests that a complete Ellesmerian section probably underlies the eastern part and that a truncated Ellesmerian section probably underlies the central part of the coastal plain of ANWR.

Our conclusions in conjunction with Bushnell's suggestion raises the possibility that a very broad anticline, formed during the earliest Cretaceous and not clearly related to either extensional faulting along the Barrow arch or Brooks Range thrusting, underlies the LCU in northeasternmost Alaska.

AAPG Search and Discovery Article #91024©1989 AAPG Pacific Section, May 10-12, 1989, Palm Springs, California.