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This DGGS Raw Data File presents 40Ar/39Ar age dating results for selected igneous rocks encountered in the Styx River area of the western Alaska Range. Crystallization ages on biotite and hornblende from plutonic rocks range from about ~60 to ~63 Ma, while a sericite alteration age in plutonic rocks altered by a dike swarm also is around ~63 Ma. Sericite alteration associated with a copper-molybdenum porphyry ranges from ~10 to ~11 Ma. Analyses were performed by the University of Alaska Fairbanks Geochronology Laboratory, and results were reported by Paul Layer and Jeff Benowitz. This data release includes the following products: a summary of sample collection methods, the laboratory report, analytical data tables...
This report presents the findings of a geologic and geotechnical evaluation of a landslide at the Yukon River bridge (the E.L. Patton Bridge). The Yukon River bridge landslide occurred in fall 2012 between approximately 375 and 575 feet west of the bridge. Although there was no damage to the bridge foundation, the landslide's close proximity to the bridge and concerns over additional failures prompted multiple evaluations, including landslide documentation, drainage assessments, and geotechnical studies. This report was prepared to convey the general characteristics of the rock mass, characteristics of rock discontinuities, and the geomorphic expression of the 2012 landslide in the vicinity of the bridge. We determined...
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