Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 30 June 1989:
Vol. 244. no. 4912, pp. 1565 - 1568
DOI: 10.1126/science.244.4912.1565
Prev | Table of Contents | Next

Articles

40Ar-39Ar Dating of the Manson Impact Structure: A Cretaceous-Tertiary Boundary Crater Candidate

M. J. KUNK 1, G. A. IZETT 1, R. A. HAUGERUD 2, and J. F. SUTTER 3

1 U.S. Geological Survey, Reston, VA 22092.
2 U.S. Geological Survey, Denver, CO 80225.
3 U.S. Geological Survey, Menlo Park, CA 94025.

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 ± 1.0 million years ago, an age that is indistinguishable from that of the K-T boundary, within the limits of analytical precision.

Submitted on February 6, 1989
Accepted on May 15, 1989


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Some personal thoughts on stratigraphic precision in the twentieth century.
H. S. Torrens (2002)
Geological Society, London, Special Publications 192, 251-272
   Abstract »    PDF »
Extraterrestrial impacts on earth: the evidence and the consequences.
R. A. F. Grieve (1998)
Geological Society, London, Special Publications 140, 105-131
   Abstract »    PDF »
The Manson Impact Structure: 40Ar/39Ar Age and Its Distal Impact Ejecta in the Pierre Shale in Southeastern South Dakota.
G. A. Izett, G. A. Izett, W. A. Cobban, J. D. Obradovich, and M. J. Kunk (1993)
Science 262, 729-732
   Abstract »    PDF »
Coeval 40Ar/39Ar Ages of 65.0 Million Years Ago from Chicxulub Crater Melt Rock and Cretaceous-Tertiary Boundary Tektites.
C. C. Swisher, C. C. Swisher III, J. M. Grajales-Nishimura, A. Montanari, S. V. Margolis, P. Claeys, W. Alvarez, P. Renne, E. Cedillo-Pardoa, F. J-M. R. Maurrasse, et al. (1992)
Science 257, 954-958
   Abstract »    PDF »
40Ar/39Ar Age of Cretaceous-Tertiary Boundary Tektites from Haiti.
G. A. Izett, G. A. IZETT, G. B. DALRYMPLE, and L. W. SNEE (1991)
Science 252, 1539-1542
   Abstract »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)