Using U-Pb ages of Miocene tufa for correlation in a terrestrial succession, Barstow Formation, California

Publication Type  Journal Article
Year of Publication  2005
Authors  Cole, J. M.; Rasbury, E. T.; Hanson, G. N.; Montanez, I. P.; Pedone, V. A.
Journal Title  Geological Society of America Bulletin
Volume  117
Issue  3-4
Pages  276-287
Journal Date  Mar-Apr
ISBN Number  0016-7606
Accession Number  ISI:000227480200002
Key Words  geochronology; continental stratigraphy; uranium-lead method; calcite; lakes; southern california; mojave desert; carbonate rocks; yucca mountain; mono lake; uranium; calcite; geochronology; nevada; time

Sedimentary rocks and associated fossils are the direct record of past life and its environmental context. Few methods allow direct and precise dating of this important archive, making it difficult to correlate climate, biologic, and tectonic events preserved in terrestrial records. We sampled lacustrine tufa calcite from the middle member of the Miocene Barstow Formation to further test the feasibility of uranium-lead dating of terrestrial carbonates. Five samples yield U-Pb ages (2sigma) of 14.81 +/- 0.39 Ma, 15.30 +/- 0.25 Ma, 15.39 +/- 0.15 Ma, 16.14 +/- 0.40 Ma, and 16.24 +/- 0.23 Ma. These precise ages are consistent with existing ages from K-Ar and Ar-49/Ar-39 dating of intercalated volcanic ashes. Our most precise U-Pb age on tufa has an uncertainty of <1% (150 ka), which is equivalent to uncertainties for K-Ar ages from the same time period. Our results indicate that U-Pb dating of carefully sampled and screened sedimentary carbonates provides much needed age constraints in purely terrestrial sequences and can be a powerful tool for correlation even in deposits with structural complexity and rapid facies changes.


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URL  <Go to ISI>://000227480200002
DOI  Doi 10.1130/B25553.1