Uranium-Series Dating of Secondary Carbonate and Silica Precipitates Relating to Fault Movements in the Nevada Test Site Region and of Caliche and Travertine Samples from the Amargosa Desert

摘要

Fault associated secondary carbonate and opal samples from the Nevada Test Site area together with travertine samples from the Amargosa Desert were dated by the uranium-series disequilibrium method. Analyses of secondary carbonate samples from Yucca Mountain and from Crater and Yucca Flats yielded minimum ages for the last significant displacements of associated faults between 27,000 and 219,000 years. Dating results of an opaline carbonate rock sample from a fault on the east side of Yucca Mountain indicate that the age of the deposit is greater than 360,000 years. Two dates of travertine vein samples show that spring discharge was occurring before about 360,000 years ago in the Kinney area of the Amargosa Desert. Ages obtained for travertine laminae from the Furnace Creek Wash area suggest that significant movement along this low-angle fault occurred more than 132,000 years ago. 5 refs., 1 fig., 4 tabs. (ERA citation 10:032393)