Denali fault slip rates and Holocene–late Pleistocene kinematics of central Alaska
- A. Matmon*1,
- D.P. Schwartz1,
- P.J. Haeussler2,
- R. Finkel3,
- J.J. Lienkaemper4,
- H.D. Stenner4 and
- TE. Dawson4
- 1U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025, USA
- 2U.S. Geological Survey, 4200 University Drive, Anchorage, Alaska 99508, USA
- 3Lawrence Livermore National Laboratory, Livermore, California 94550, USA
- 4U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025, USA
Abstract
The Denali fault is the principal intracontinental strike-slip fault accommodating deformation of interior Alaska associated with the Yakutat plate convergence. We obtained the first quantitative late Pleistocene–Holocene slip rates on the Denali fault system from dating offset geomorphic features. Analysis of cosmogenic 10Be concentrations in boulders (n = 27) and sediment (n = 13) collected at seven sites, offset 25–170 m by the Denali and Totschunda faults, gives average ages that range from 2.4 ± 0.3 ka to 17.0 ± 1.8 ka. These offsets and ages yield late Pleistocene– Holocene average slip rates of 9.4 ± 1.6, 12.1 ± 1.7, and 8.4 ± 2.2 mm/yr−1 along the western, central, and eastern Denali fault, respectively, and 6.0 ± 1.2 mm/yr−1 along the Totschunda fault. Our results suggest a westward decrease in the mean Pleistocene– Holocene slip rate. This westward decrease likely results from partitioning of slip from the Denali fault system to thrust faults to the north and west.
Footnotes
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↵*Present address: Institute of Earth Sciences, Hebrew University, Jerusalem, Israel, 91904
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↵GSA Data Repository item 2006132, DR1, offset measurements of displaced features along the Denali fault and error calculations; DR2, snow-cover measurement stations; and DR3, sampling sites and cosmogenic model ages along the Denali fault, is available online at www.geosociety.org/pubs/ft2006.htm, or on request from editing{at}geosociety.org or Documents Secretary, GSA, P.O. Box 9140, Boulder, CO 80301, USA.
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- Accepted 18 March 2006.
- Received 26 October 2005.
- Revision received 16 March 2006.
- Geological Society of America
