sup 40 Ar- sup 39 Ar dating of the manson impact structure: A cretaceous-tertiary boundary crater candidate

Journal Article · Fri Jun 30 00:00:00 EDT 1989 · Science (Washington, D.C.); (USA)

DOI:https://doi.org/10.1126/science.244.4912.1565· OSTI ID:7058907

Kunk, M J; Sutter, J F ^[1]; Izett, G A ^[2]; Haugerud, R A ^[3]

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1. Geological Survey, Reston, VA (USA)
2. Geological Survey, Denver, CO (USA)
3. Geological Survey, Menlo Park, CA (USA)

The mineralogy of shocked mineral and lithic grains in the Cretaceous-Tertiary (K-T) boundary claystone worldwide is most consistent with a bolide impact on a continent. Both the concentrations and sizes of these shocked grains are greatest in the western interior of North America. These data suggest that the Manson impact structure in north-central Iowa is a viable candidate for the K-T boundary impact event. Argon-40-argon-39 age spectrum dating of shocked microcline from the crystalline central uplift of the Manson impact structure indicates that there was severe argon-40 loss at 65.7 {plus minus} 1.0 million years ago, an age that is indistinguishable from that of the K-T boundary, within the limits of analytical precision. 36 refs., 2 figs., 1 tab.

• OSTI ID: 7058907
• Journal Information: Science (Washington, D.C.); (USA), Vol. 244:4912; ISSN 0036-8075
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ROCKS
ISOTOPE DATING
ARGON 39
ARGON 40
CRETACEOUS PERIOD
EXPERIMENTAL DATA
AGE ESTIMATION
ARGON ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
DATA
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOLOGIC AGES
INFORMATION
ISOTOPES
LIGHT NUCLEI
MESOZOIC ERA
NUCLEI
NUMERICAL DATA
RADIOISOTOPES
STABLE ISOTOPES
YEARS LIVING RADIOISOTOPES
580000* - Geosciences