Dating fault-associated Quaternary material from the Nevada Test Site using uranium-series methods
Accumulations of secondary carbonate in the arid southern Great Basin are frequently associated with or disturbed by Basin and Range faults. In appropriate situations, these materials may be dated by uranium-series disequilibrium techniques using a combined chemical-leach and graphical correction procedure to account for included detrital material. The dates provide a minimum, a maximum, or a bracket of ages for tectonic activity on the faults investigated. Carbonates (e.g., travertine, calcrete, and caliche) were dated from the Carpetbag, Yucca, Boundary, and Cane Spring Faults at the Nevada Test Site. Multiple ages obtained from the same fault were always in correct relative order where stratigraphic relationships were known. Many of the ages obtained agree with age estimates based on geomorphology. A bracket of ages obtained for three samples from the Carpetbag Fault suggest that the last natural movement occurred more than 37,000 but less than 93,000 yr ago. A maximum age of 35,000 yr is obtained for natural movement on the Yucca Fault. A total of six repeatedly disturbed carbonate samples could provide only an obviously high maximum age of 217,000 yr for movement on the Boundary Fault. Tufaceous travertines from the Cane Spring Fault and a related normal fault suggest a probable low-minimum age of 41,000 yr for the last movement. Initial attempts were made to determine the potential for age dating fault zone secondary silica using uranium-series disequilibrium techniques. The old ages obtained (greater than or equal to 700,000 yr) support the contention that most Quaternary tectonism has been restricted to areas of recent subsidence, the deep alluvial basins. These results also validate recent attempts to determine U-Pb ages for uraniferous opals.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5399750
- Report Number(s):
- UCRL-53231; ON: DE82009018
- Country of Publication:
- United States
- Language:
- English
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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
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Related Subjects
GEOLOGIC FAULTS
ISOTOPE DATING
NEVADA TEST SITE
CARBONATE ROCKS
EXPERIMENTAL DATA
QUATERNARY PERIOD
SILICA
THORIUM 230
URANIUM 234
URANIUM 238
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
AGE ESTIMATION
ALPHA DECAY RADIOISOTOPES
CENOZOIC ERA
CHALCOGENIDES
DATA
EVEN-EVEN NUCLEI
GEOLOGIC AGES
GEOLOGIC STRUCTURES
HEAVY NUCLEI
INFORMATION
ISOTOPES
MINERALS
NUCLEI
NUMERICAL DATA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
RADIOISOTOPES
ROCKS
SEDIMENTARY ROCKS
SILICON COMPOUNDS
SILICON OXIDES
THORIUM ISOTOPES
URANIUM ISOTOPES
YEARS LIVING RADIOISOTOPES
580100* - Geology & Hydrology- (-1989)