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GEOREF RECORD

Structural provinces of the northeastern Brooks Range, Arctic National Wildlife Refuge, Alaska

Wesley K. Wallace and Catherine L. Hanks
Structural provinces of the northeastern Brooks Range, Arctic National Wildlife Refuge, Alaska
AAPG Bulletin (July 1990) 74 (7): 1100-1118

Abstract

The dominant Cenozoic structures of the northeastern Brooks Range are anticlinoria with cores of sub-Mississippian rocks, reflecting a regional north-vergent duplex with a floor thrust in the sub-Mississippian sequence and a roof thrust in the Mississippian Kayak Shale. The number of horses forming each anticlinorium and the structural style of the overlying Mississippian and younger cover sequence varies regionally, providing a basis for dividing the northeastern Brooks Range into structural provinces. In the western province, each anticlinorium contains a single horse, and shortening above the Kayak Shale was accommodated mainly by detachment folds. To the north in the Sadlerochit Mountains, the Kayak Shale is depositionally discontinuous and rocks elsewhere separated by this detachment deformed together. In the eastern province, each anticlinorium contains multiple horses, and shortening above the Kayak Shale was accommodated largely by thrust duplication of Mississippian through Triassic rocks. In the narrow central province, the Devonian Okpilak batholith was detached from its roots, internally shortened along shear zones and by penetrative strain, and transported northward. Because the Kayak Shale is locally absent, the Mississippian and younger cover sequence deformed in part penetratively along with the batholith. East-northeast trends formed where sub-Mississippian rocks were not involved in deformation, and probably are normal to the direction of Cenozoic tectonic transport. East trends formed where sub-Mississippian rocks were involved in deformation, and probably reflect a pre-Mississippian structural grain. At any given location, east trends generally post-date east-northeast trends, reflecting a drop over time of the basal detachment into sub-Mississippian rocks.


ISSN: 0149-1423
EISSN: 1558-9153
Coden: AABUD2
Serial Title: AAPG Bulletin
Serial Volume: 74
Serial Issue: 7
Title: Structural provinces of the northeastern Brooks Range, Arctic National Wildlife Refuge, Alaska
Affiliation: Univ. Alaska, Geophys. Inst., Fairbanks, AK, United States
Pages: 1100-1118
Published: 199007
Text Language: English
Publisher: American Association of Petroleum Geologists, Tulsa, OK, United States
References: 68
Accession Number: 1990-050223
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., chart, geol. sketch maps
N69°34'60" - N70°19'60", W147°00'00" - W142°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute.
Update Code: 1990
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