Using U-Pb ages of Miocene tufa for correlation in a terrestrialsuccession, Barstow Formation, California
Cole, Jennifer M; Rasbury, E Troy; Hanson, Gilbert N; Montanez, IsabelP; Pedone, Vicki A (2005) Using U-Pb ages of Miocene tufa for correlation in a terrestrialsuccession, Barstow Formation, California. Geological Society of America Bulletin, vol.117, no.3-4, pp.276-287,Apr 2005
| Authors | Cole, Jennifer M; Rasbury, E Troy; Hanson, Gilbert N; Montanez, IsabelP; Pedone, Vicki A |
|---|---|
| Year | 2005 |
| Title | Using U-Pb ages of Miocene tufa for correlation in a terrestrialsuccession, Barstow Formation, California |
| Source | Geological Society of America Bulletin, vol.117, no.3-4, pp.276-287,Apr 2005 |
| ISSN | 0016-7606 |
| GeoRef | 2005-031003 |
| Keywords | absolute age; Barstow Formation; calcite; California; carbonates;Cenozoic; chemically precipitated rocks; correlation; dates;depositional environment; lacustrine environment; Miocene; Neogene;precision; San Bernardino County California; sedimentary rocks;terrestrial environment; Tertiary; tufa; U/Pb; United States |
| Notes | With GSA Data Repository Item 2005058 |
| DOI | 10.1130/B25553.1 |
Abstract
Sedimentary rocks and associated fossils are the direct record of pastlife and its environmental context. Few methods allow direct andprecise dating of this important archive, making it difficult tocorrelate climate, biologic, and tectonic events preserved interrestrial records. We sampled lacustrine tufa calcite from themiddle member of the Miocene Barstow Formation to further test thefeasibility of uraniumlead dating of terrestrial carbonates. Fivesamples yield U-Pb ages (2sigma ) of 14.81+ or -0.39 Ma, 15.30+ or-0.25 Ma, 15.39+ or -0.15 Ma, 16.14+ or -0.40 Ma, and 16.24+ or -0.23Ma. These precise ages are consistent with existing ages from K-Ar and(super 40) Ar/ (super 39) Ar dating of intercalated volcanic ashes.Our most precise U-Pb age on tufa has an uncertainty of <1% (150ka), which is equivalent to uncertainties for K-Ar ages from the sametime period. Our results indicate that U-Pb dating of carefullysampled and screened sedimentary carbonates provides much needed ageconstraints in purely terrestrial sequences and can be a powerful toolfor correlation even in deposits with structural complexity and rapidfacies changes.