Cohen, B. E. , Mark, D. F. , Lee, M. R. and Simpson, S. L. (2017) A new high-precision 40Ar/39Ar age for the Rochechouart impact structure: at least 5 Ma older than the Triassic-Jurassic boundary. Meteoritics and Planetary Science, 52(8), pp. 1600-1611. (doi: 10.1111/maps.12880)
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Abstract
The Rochechourt impact structure in south-central France, with maximum diameter of 40–50 km, has previously been dated to within 1% uncertainty of the Triassic–Jurassic boundary, at which time ~30% of global genera became extinct. To evaluate the temporal relationship between the impact and the Triassic–Jurassic boundary at high precision, we have re-examined the structure's age using multicollector ARGUS-V 40Ar/39Ar mass spectrometry. Results from four aliquots of impact melt are highly reproducible, and yield an age of 206.92 ± 0.20/0.32 Ma (2σ, full analytical/external uncertainties). Thus, the Rochechouart impact structure predates the Triassic–Jurassic boundary by 5.6 ± 0.4 Ma and so is not temporally linked to the mass extinction. Rochechouart has formerly been proposed to be part of a multiple impact event, but when compared with new ages from the other purported “paired” structures, the results provide no evidence for synchronous impacts in the Late Triassic. The widespread Central Atlantic Magmatic Province flood basalts remain the most likely cause of the Triassic–Jurassic mass extinction.
| Item Type: | Articles |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Mark, Professor Darren and Cohen, Dr Benjamin and Lee, Professor Martin and Simpson, Ms Sarah |
| Authors: | Cohen, B. E., Mark, D. F., Lee, M. R., and Simpson, S. L. |
| College/School: | College of Science and Engineering > School of Geographical and Earth Sciences College of Science and Engineering > Scottish Universities Environmental Research Centre |
| Journal Name: | Meteoritics and Planetary Science |
| Publisher: | Wiley |
| ISSN: | 1086-9379 |
| ISSN (Online): | 1945-5100 |
| Published Online: | 16 May 2017 |
| Copyright Holders: | Copyright © 2017 The Authors. Meteoritics and Planetary Science |
| First Published: | First published in Meteoritics and Planetary Science 52(8): 1600-1611 |
| Publisher Policy: | Reproduced under a Creative Commons license |
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