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The AAPG/Datapages Combined Publications Database

AAPG Special Volumes

Abstract

R. Swennen, F. Roure, and J. W. Granath, eds., Deformation, fluid flow, and reservoir appraisal in foreland fold and thrust belts: AAPG Hedberg Series, no. 1, p. 187-214.

Copyright © 2004 by The American Association of Petroleum Geologists.

DOI:10.1306/1025691H13117

Tertiary Thrust Systems and Fluid Flow beneath the Beaufort Coastal Plain (1002 Area), Arctic National Wildlife Refuge, Alaska, U.S.A.

Christopher J. Potter,1 John A. Grow,2 William J. Perry,3 Thomas E. Moore,4 Paul B. O'Sullivan,5 Jeffrey D. Phillips,6 Richard W. Saltus7

1U.S. Geological Survey, Denver, Colorado, U.S.A.
2U.S. Geological Survey, Denver, Colorado, U.S.A.
3U.S. Geological Survey, Denver, Colorado, U.S.A.
4U.S. Geological Survey, Menlo Park, California, U.S.A.
5Apatite to Zircon, Inc., Viola, Idaho, U.S.A.
6U.S. Geological Survey, Denver, Colorado, U.S.A.
7U.S. Geological Survey, Denver, Colorado, U.S.A.

ABSTRACT

Beneath the Arctic coastal plain (commonly referred to as ldquothe 1002 areardquo) in the Arctic National Wildlife Refuge, northeastern Alaska, United States, seismic reflection data show that the northernmost and youngest part of the Brookian orogen is preserved as a Paleogene to Neogene system of blind and buried thrust-related structures. These structures involve Proterozoic to Miocene (and younger?) rocks that contain several potential petroleum reservoir facies. Thermal maturity data indicate that the deformed rocks are mature to overmature with respect to hydrocarbon generation. Oil seeps and stains in outcrops and shows in nearby wells indicate that oil has migrated through the region; geochemical studies have identified three potential petroleum systems. Hydrocarbons that were generated from Mesozoic source rocks in the deformed belt were apparently expelled and migrated northward in the Paleogene, before much of the deformation in this part of the orogen. It is also possible that Neogene petroleum, which was generated in Tertiary rocks offshore in the Arctic Ocean, migrated southward into Neogene structural traps at the thrust front. However, the hydrocarbon resource potential of this largely unexplored region of Alaska's North Slope remains poorly known.

In the western part of the 1002 area, the dominant style of thin-skinned thrusting is that of a passive-roof duplex, bounded below by a detachment (floor thrust) near the base of Lower Cretaceous and younger foreland basin deposits and bounded above by a north-dipping roof thrust near the base of the Eocene. East–west-trending, basement-involved thrusts produced the Sadlerochit Mountains to the south, and buried, basement-involved thrusts are also present north of the Sadlerochit Mountains, where they appear to feed displacement into the thin-skinned system. Locally, late basement-involved thrusts postdate the thin-skinned thrusting. Both the basement-involved thrusts and the thin-skinned passive-roof duplex were principally active in the Miocene.

In the eastern part of the 1002 area, a northward-younging pattern of thin-skinned deformation is apparent. Converging patterns of Paleocene reflectors on the north flank of the Sabbath syncline indicate that the Aichilik high and the Sabbath syncline formed as a passive-roof duplex and piggyback basin, respectively, just behind the Paleocene deformation front. During the Eocene and possibly the Oligocene, thin-skinned thrusting advanced northward over the present location of the Niguanak high. A passive-roof duplex occupied the frontal part of this system. The Kingak and Hue shales exposed above the Niguanak high were transported into their present structural position during the Eocene to Oligocene motion on the long thrust ramps above the present south flank of the Niguanak high. Broad, basement-cored subsurface domes (Niguanak high and Aurora dome) formed near the deformation front in the Oligocene, deforming the overlying thin-skinned structures and feeding a new increment of displacement into thin-skinned structures directly to the north. Deformation continued through the Miocene above a detachment in the basement. Offshore seismicity and Holocene shortening documented by previous workers may indicate that contractional deformation continues to the present day.

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