| Abstract: | New 40Ar-39Ar total fusion ages have been obtained on sanidine from tuffs in the zone of Mantelliceras saxbii (equivalent to the same subzone of the European ammonite zonation) and the zone of Graysonites wooldridgei (equivalent to the European subzone of Neostlingoceras carcitanense). Ages of 98.98??0.38 Ma and 99.16??0.37 Ma, for these zones, respectively, place new constraints on the age of the Albian/Cenomanian boundary. If the base of the Cenomanian is to be defined, as currently proposed, as the FAD of the planktonic foraminifera Rotalipora globotruncanoides then the Albian/Cenomanian boundary will be at least as old as 99.2??0.4 Ma. Some 50??10m of undated sediments lie below the lowest find of R. globotruncanoides and above bono fide uppermost Albian strata. |
| Genre: | Article |
| ProdID: | 70024588 |
| Citation Author: | Obradovich, J. D.; Matsumoto, T.; Nishida, T.; Inoue, Y. |
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| Citation End Page: | 153 |
| Citation Issue: | 6 |
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| Citation Language: | English |
| Citation Larger Work Title: | Proceedings of the Japan Academy Series B: Physical and Biological Sciences |
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| Citation Number Of Pages: | 5 |
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| Citation Search Results Text: | Integrated biostratigraphic and radiometric study on the Lower Cenomanian (Cretaceous) of Hokkaido, Japan; 2002; Article; Journal; Proceedings of the Japan Academy Series B: Physical and Biological Sciences; Obradovich, J. D.; Matsumoto, T.; Nishida, T.; Inoue, Y. |
| Citation Start Page: | 149 |
| Citation Volume: | 78 |
| Citation Year: | 2002 |
| Type: | citation/reference |
| Text: | Integrated biostratigraphic and radiometric study on the Lower Cenomanian (Cretaceous) of Hokkaido, Japan; 2002; Article; Journal; Proceedings of the Japan Academy Series B: Physical and Biological Sciences; Obradovich, J. D.; Matsumoto, T.; Nishida, T.; Inoue, Y. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Tue, 1 Jan 2002 00:00 -0600 |
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