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Boltysh, another end-cretaceous impact

Kelley, Simon P. and Gurov, Eugene (2002). Boltysh, another end-cretaceous impact. Meteoritics and Planetary Science, 37(8) pp. 1031–1043.

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The Chixculub impact occurred at the Cretaceous/Tertiary (K/T) boundary, and although several other Late Cretaceous and Paleogene impact craters have, at times, been linked with the K/T boundary, isotope geochronology has demonstrated that all have significantly different ages. The currently accepted age of the 24 km diameter Boltysh crater, a K-Ar whole-rock age, places it in the Coniacian at 88 +/- 3 Ma. However, comprehensive Ar-Ar dating of a range of melt samples yields a mean age of 65.17 +/- 0.64 Ma, within errors of the K/T boundary. Several of the fresh samples exhibit signs of excess argon but this seems to be concentrated in rapidly crystallized glass-rich samples.
The Ar-Ar age confirms an earlier fission track measurement and thus two dating techniques have yielded an age within errors of the K/T boundary for this crater. Crucially, although the ages of Boltysh and Chixculub are within errors, they may not have formed synchronously. Craters of 24 kin diameter occur much more commonly than impacts of Chixculub dimensions, but their proximity does raise the important question of how many impacts there might have been close to the K/T boundary.

Item Type: Journal Item
ISSN: 1086-9379
Extra Information: Some of the symbols may not have transferred correctly into this bibliographic record and/or abstract.
Keywords: terresrtial impact; mass extinction; ejecta; mass instinction; boundary event; age; eocene; crater; rocks; earth; USSR
Academic Unit/School: Institute of Educational Technology (IET)
Item ID: 4196
Depositing User: Simon Kelley
Date Deposited: 04 Jul 2006
Last Modified: 13 Dec 2019 08:53
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