dc.contributor.author	Bemis, Sean Patrick, 1979-
dc.date.accessioned	2010-07-30T22:17:52Z
dc.date.available	2010-07-30T22:17:52Z
dc.date.issued	2010-03
dc.description	xvi, 121 p. : ill. (some col.), maps (some col.) Also includes two large-scale maps in two separate pdf files. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.	en_US
dc.description.abstract	Deformation across plate boundaries often occurs over broad zones with relative motions between plates typically accommodated by faults of different styles acting together in a complex system. Collision of the Yakutat microplate within the Alaskan portion of the Pacific-North America plate boundary drives deformation over 600 km away where the Denali fault divides predominantly rigid crustal block motions of southern Alaska from distributed deformation in central Alaska. Quaternary geologic mapping along the Nenana River valley and the Japan Hills of the northern foothills of the Alaska Range defines zones of Quaternary thrust faulting recorded in the progressive deformation of Pleistocene fluvial terraces. I use topographic profiles of these terraces and paleoseismic trenching of fault scarps to characterize the Quaternary activity and constrain the subsurface geometry of these faults. Radiocarbon and cosmogenic exposure dating methods provide age control on the stratigraphy in the trenches and landforms offset by these faults. These observations define a 1-1.5 mm/yr slip rate for the Gold King fault which changes laterally from a north-vergent thrust into a north and south vergent thrust wedge that uplifts the Japan Hills. Along the Nenana River valley, the progressive deformation of Pleistocene surfaces defines a north-vergent critically-tapered thrust wedge. The geometry of progressive uplift and folding requires a near planar, south-dipping basal thrust fault with two major north-dipping backthrusts. All three faults were active simultaneously on a scale of 10 4 yrs with slip rates of 0.25-1 mm/yr, until the late Pleistocene when we infer the retreat of glacial ice from the main axis of the Alaska Range caused a change in thrust wedge dynamics. I use the orientation of Quaternary deformation north of the Denali fault to show that strain is highly partitioned and establish geologic constraints on the regional horizontal stress orientation. North of the Denali fault, fault-normal principal shortening accommodates 3-5 mm/yr of strain transfer across the Denali fault system. Two appendices contain additional results of paleoseismic trenching and neotectonic investigations across 4 active faults near the Nenana River. This dissertation includes previously unpublished co-authored material.	en_US
dc.description.sponsorship	Committee in charge: Ray Weldon, Chairperson, Geological Sciences; Joshua Roering, Member, Geological Sciences; David Schmidt, Member, Geological Sciences; Douglas Kennett, Outside Member, Anthropology	en_US
dc.identifier.uri	https://hdl.handle.net/1794/10563
dc.language.iso	en_US	en_US
dc.publisher	University of Oregon	en_US
dc.relation.ispartofseries	University of Oregon theses, Dept. of Geological Sciences, Ph. D., 2010;
dc.subject	Alaska Range (Alaska)	en_US
dc.subject	Fold-thrust belts	en_US
dc.subject	Denali fault	en_US
dc.subject	Thrust faulting	en_US
dc.subject	Geomorphology	en_US
dc.subject	Plate tectonics -- Alaska -- Alaska Range	en_US
dc.subject	Geology, Stratigraphic -- Quaternary
dc.title	Moletrack scarps to mountains: Quaternary tectonics of the central Alaska Range	en_US
dc.title.alternative	Quaternary tectonics of the central Alaska Range	en_US
dc.type	Thesis	en_US

Moletrack scarps to mountains: Quaternary tectonics of the central Alaska Range

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