Stratigraphic controls on lateral variations in the structural style of northeastern Brooks Range, Arctic National Wildlife Refuge, Alaska

Conference · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6084331

Wallace, W K; Hanks, C L

The structural style of the range-front region of the northeastern Brooks Range in Arctic National Wildlife Refuge (ANWR) is strongly controlled by (1) the existence of detachment horizons in both pre-Mississippian rocks and the unconformably overlying Mississippian to Lower Cretaceous cover sequence, and (2) lithology and structural competency of the pre-Mississippian rocks. These variables strongly influence lateral changes in structural style. The Brooks Range of northwestern ANWR is dominated by a series of narrow linear anticlinoria, whereas in northeastern ANWR the Brooks Range is characterized by only two broad and strongly arcuate anticlinoria. In both areas, the anticlinoria are controlled by the geometry of a duplex bounded by a floor thrust in pre-Mississippian rocks and a roof thrust in the Kayak Shale, near the base of the cover sequence. In the west, where the pre-Mississippian partially consists of structurally competent carbonates, each anticlinorium marks a single horse in the duplex. However, in the east, pre-Mississippian rocks are relatively incompetent and each anticlinorium is cored by multiple horses. In the west, shortening above the roof thrust is by detachment folding, except where the shale detachment horizon is depositionally absent. In contrast, in eastern ANWR shortening above the roof thrust is by major thrust duplication of the entire cover sequence, perhaps due to lithology and thickness changes within the detachment horizon.

• OSTI ID: 6084331
• Report Number(s): CONF-880301-
• Country of Publication: United States
• Language: English

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