Cohen, B. E. , Mark, D. F. , Cassata, W. S., Kalnins, L. M., Lee, M. , Smith, C. L. and Shuster, D. L. (2023) Synchronising rock clocks of Mars’ history: resolving the shergottite 40Ar/39Ar age paradox. Earth and Planetary Science Letters, 621, 118373. (doi: 10.1016/j.epsl.2023.118373)
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Abstract
The shergottites are the most abundant and diverse group of Martian meteorites and provide unique insights into the mafic volcanic and igneous history of Mars. Their ages, however, remain a source of debate. Different radioisotopic chronometers, including 40Ar/39Ar, have yielded discordant ages, leading to conflicting interpretations on whether the shergottites originate from young (mostly <700 Ma) or ancient (>4,000 Ma) Martian volcanoes. To address this issue, we have undertaken an 40Ar/39Ar investigation of seven shergottite meteorites utilizing an innovative approach to correcting data for cosmogenic isotope production and resolution of initial trapped components which, crucially, do not require assumptions concerning the sample's geologic context. Our data yield statistically robust 40Ar/39Ar isochron ages ranging from 161 ± 9 Ma to 540 ± 63 Ma (2σ), synchronous with the U-Pb, Rb-Sr, and Sm-Nd ages for the respective meteorites. These data indicate that, despite experiencing shock metamorphism, the shergottites were sourced from the youngest volcanoes on Mars.
| Item Type: | Articles |
|---|---|
| Additional Information: | This work was funded by the UK Science and Technology Facilities Council (grants ST/H002960/1, and ST/K000918/1 to D.F.M. and M.R.L.). W.S.C. was supported by the NASA Mars Fundamental Research Program (grant NNH14AX56I) and an LLNL Laboratory Directed Research and Development project (20-LW-008). Portions of this work were performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. L.M.K. is supported by a Royal Society of Edinburgh Personal Research Fellowship funded by the Scottish Government. D.L.S. was supported by the Ann and Gordon Getty Foundation. NERC are thanked for continued funding of the Argon Isotope Facility at SUERC. |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Mark, Professor Darren and Smith, Dr Caroline and Lee, Professor Martin and Cohen, Dr Benjamin |
| Authors: | Cohen, B. E., Mark, D. F., Cassata, W. S., Kalnins, L. M., Lee, M., Smith, C. L., and Shuster, D. 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: | Earth and Planetary Science Letters |
| Publisher: | Elsevier |
| ISSN: | 0012-821X |
| ISSN (Online): | 1385-013X |
| Published Online: | 15 September 2023 |
| Copyright Holders: | Copyright © 2023 The Authors |
| First Published: | First published in Earth and Planetary Science Letters 621: 118373 |
| Publisher Policy: | Reproduced under a Creative Commons License |
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