Antislope scarps, gravitational spreading, and tectonic faulting in the western Yakutat microplate, south coastal Alaska
Mccalpin JP, Bruhn RL, Pavlis TL, Gutierrez F, Lucha P. 2011. Antislope scarps, gravitational spreading, and tectonic faulting in the western Yakutat microplate, south coastal Alaska. Geosphere. 7(5)
Mountain ridges in the western Yakutat microplate are riddled with swarms of antislope scarps and troughs. These landforms were previously interpreted as gravity failures, but if partly or wholly tectonic, they represent part of the strain budget from ongoing plate collision. To determine scarp origin, we mapped landforms, bedrock structure, and trenched scarps at Kushtaka Mountain and south of Martin Lake. The Kushtaka scarps paralleled west-dipping coal and sandstone beds in the Tertiary Kultieth Formation, and were spaced 35–60 m apart with heights of 1–4 m. Structural and paleosol relationships in a 6-m-long, 1.3-m-deep trench indicate the scarp was produced by Holocene creep on a normal fault underlying the scarp. The Kushtaka scarps thus represent toppling-style slip on bedding-plane faults in the eastern limb of a syncline, as the fold “unfolds” due to gravitational spreading.
- Type
- Journal Article
- Authors
- Mccalpin, J; Bruhn, R; Pavlis, T; Gutierrez, F; Lucha, P
- Units
- WRST
- Keywords
- anitslope, Martin Lake, microplate, Saint Elias, Tectonic, Yakutat