Isotopic dating of Lava Creek B tephra in terrace deposits along the Wind River, Wyoming--Implications for post 0. 6 Ma uplift of the Yellowstone hotspot
- U.S.G.S., Denver, CO (United States)
- Univ. of Wyoming, Laramie, WY (United States). Dept. of Geology and Geophysics
Along the Wind River near Kinnear (Pavillon quadrangle), a meter-thick tephra layer occurs near the middle of a main-stem gravel deposit about 100 m above the river. On Muddy Ridge 25 km east of Kinnear, a Lava Creek B tephra layer occurs at the base of a terrace deposit about 100 m above Muddy Creek. Another Lava Creek B tephra site 67 km northwest and upstream from Kinnear occurs within main-stem gravels of a terrace deposit 145 m above the river. This upstream increase of 45 m of the tephra horizon raises the concern that the two tephra layers might not be of the same age. All three tephras contain the same assemblage of phenocrysts as that in the Lava Creek Tuff, Member B in Yellowstone National Park and the Lava Creek B volcanic ash bed of the Western U.S., and therefore they are arguably correlatives. The authors confirmed this petrographic correlation by isotopic dating of sanidine crystals recovered from cm-size pumice lapilli in the Kinnear tephra and from coarse-grained tephra at the Muddy Creek site. Laser total-fusion Ar-40-Ar-39 ages of sanidine from the two sites are coeval, 0.66[plus minus]0.01 Ma and 0.67[plus minus]0.01 Ma at Muddy Creek. Conventional K-Ar dating of sanidine from the tephra at the Cl453 site resulted in an age of 0.60[plus minus]0.02 Ma. Glass-mantled zircon crystals from the Cl453 site yielded a fission-track age of 0.67[plus minus]0.16 Ma. These isotopic ages are compatible with conventional K-Ar, Ar-40-Ar-39, and fission-track ages of the Lava Creek Tuff, Member B in Yellowstone National Park and other occurrences of Lava Creek B ash beds. The authors suggest that the terrace deposit that contains the Lava Creek B tephra rises from the Kinnear site northwest up the Wind River as a result of Quaternary uplift in the area of the Yellowstone hotspot.
- OSTI ID:
- 5888196
- Report Number(s):
- CONF-921058--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 24:7; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
150200* -- Geology & Hydrology of Geothermal Systems
58 GEOSCIENCES
580000 -- Geosciences
AGE ESTIMATION
CORRELATIONS
DEVELOPED COUNTRIES
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
HOT SPOTS
IGNEOUS ROCKS
ISOTOPE DATING
NORTH AMERICA
PUBLIC LANDS
ROCKS
USA
VOLCANIC REGIONS
VOLCANIC ROCKS
WYOMING
YELLOWSTONE NATIONAL PARK