A comparative study of contrasting structural styles in the range-front region of the northeastern Arctic National Wildlife Refuge, northeastern Brooks Range, Alaska

• Main Author: Hanks, Catherine Leigh
• Other Authors: Stone, David B., Crowder, R. Keith, Keskinen, Mary J., Watts, Keith W., Ave Lallemant, Hans G., Mull, C. G.
• Format: Doctoral or Postdoctoral Thesis
• Language: unknown
• Published: 1991
• Subjects: Geology; Arctic; Fairbanks; Kayak; Brooks Range; Alaska
• Online Access: http://hdl.handle.net/11122/9376

Dissertation (Ph.D.) University of Alaska Fairbanks, 1991 The range front of the northeastern Brooks Range in the Arctic National Wildlife Refuge (ANWR) is defined by anticlinoria cored by a 'basement' complex of weakly metamorphosed sedimentary, volcanic and intrusive rocks. These anticlinoria are interpreted to reflect horses in a northward-propagating regional duplex between a floor thrust at depth in the 'basement' complex and a roof thrust near the base of the cover sequence. Lateral variations in the geometry of these range-front anticlinoria reflect changes in lithology and deformational style of both the 'basement' and its cover. Two distinct structural geometries are displayed along the range front of northeastern ANWR. To the east, the large range-front anticlinorium is interpreted to reflect multiple horses of Cenozoic age within the stratified, slightly metamorphosed sedimentary and volcanic rocks of the pre-Mississippian 'basement'. During Cenozoic thrusting, these mechanically heterogeneous rocks deformed primarily via thrusting and related folding with minor penetrative strain. The Mississippian and younger cover sequence shortened via both thrust duplication and detachment folding above a detachment in the Mississippian Kayak Shale. In contrast, to the west the pre-Mississippian rocks consist primarily of the mechanically homogeneous Devonian Okpilak batholith. The batholith was transported northward during Cenozoic thrusting and now forms a major topographic and structural high near the range front. The batholith probably shortened during thrusting as a homogeneous mass via penetrative strain. Because the Kayak Shale is thin to absent in the vicinity of the batholith, Mississippian and younger rocks remained attached to the batholith and shortened via penetrative strain and minor imbrication. These two range-front areas form the central portion of two regional transects through northeastern ANWR. General area-balanced models for both transects suggest that the amount of total shortening is ...