| Abstract: | 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. |
| Genre: | Article |
| ProdID: | 70015456 |
| Citation Author: | Kunk, M. J.; Izett, G. A.; Haugerud, R. A.; Sutter, J. F. |
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| Citation End Page: | 1568 |
| Citation Issue: | 4912 |
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| Citation Language: | English |
| Citation Larger Work Title: | Science |
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| Citation Number Of Pages: | 4 |
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| Citation Search Results Text: | 40Ar-39Ar dating of the Manson impact structure: A cretaceous-tertiary boundary crater candidate; 1989; Article; Journal; Science; Kunk, M. J.; Izett, G. A.; Haugerud, R. A.; Sutter, J. F. |
| Citation Start Page: | 1565 |
| Citation Volume: | 244 |
| Citation Year: | 1989 |
| Type: | citation/reference |
| Text: | 40Ar-39Ar dating of the Manson impact structure: A cretaceous-tertiary boundary crater candidate; 1989; Article; Journal; Science; Kunk, M. J.; Izett, G. A.; Haugerud, R. A.; Sutter, J. F. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Sun, 1 Jan 1989 00:00 -0600 |
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