Preliminary Report on Late Cenozoic Faulting and Stratigraphy in the Vicinity of Yucca Mountain, Nye County, Nevada

摘要

Mapping of surficial deposits and examination of faults in natural and trenched exposures in a 1100 sq km area around the site of a potential repository for radioactive waste at Yucca Mountain have identified 32 faults that offset or fracture Quaternary deposits. Where the amount of Quarternary offset can be estimated, dip-slip movement is on the order of 3 m or less on faults in and near Yucca Mountain. Maximum Quarternary offset within the study area may be as much as 30 m. No strike-slip movement was demonstrated nor can it be ruled out. Based on radiometric ages, correlations of stratigraphic units, and field observations, Quarternary faults are divided into three broad age groups: five faults moved between about 270,000 and 40,000 years ago; four faults moved about 1 m.y. ago and 23 faults moved probably between 2 m.y. and more than 1.2 m.y. ago. Offset of Holocene deposits has not been demonstrated. (ERA citation 10:015787)