Stable Isotope Studies of the Rochechouart Impact Structure: Sources of Secondary Carbonates and Sulphides within Allochthonous and Parautochthonous Impactites

Simpson, S.L., Boyce, A.J. , Lambert, P., Lee, M.R., Mark, D.F. and Lindgren, P. (2015) Stable Isotope Studies of the Rochechouart Impact Structure: Sources of Secondary Carbonates and Sulphides within Allochthonous and Parautochthonous Impactites. In: 46th Lunar and Planetary Science Conference, The Woodlands, TX, USA, 16-20 Mar 2015,

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Abstract

Hypervelocity impacts are among the most ubiquitous processes to affect solid bodies within our solar system [1, 2]. Although they are notoriously devastating, citing responsibility for mass extinction events and global climate perturbations, impacts can also create temporary environments which are favorable for life to thrive, if there is enough water present in the target, and sufficient energy is released as heat [1, 2]. One-third of impact structures on Earth contain fossil impact-initiated hydrothermal systems, and they are therefore being explored as potential “cradles of life” on other solid planets and satellites in our solar system [1].

We are presenting a case for the evaluation of the Mesozoic Rochechouart impact structure in France as a once-habitable environment. Initial δ 13C, δ18O and δ 34S isotope data collected in 2014 from hydrothermal carbonates and sulphides within monomict lithic impact breccia, collected from a site located 7.5km from the center of the structure at Champagnac quarry, supports our hypothesis of a warm, wet environment; we also found evidence for metabolically reduced sulphate [3]. Similar mineral assemblages can be found throughout the structure, including allochthonous breccias and low to unshocked target material. In order to explore our hypothesis further, a larger sample set was collected from various lithologies within the Champagnac site containing sulphide and carbonate mineralization for δ 13C, δ18O and δ34S isotope analysis in January 2015. These results will allow us to determine the relationships between the many hydrothermal mineral assemblages within this area of the structure, and ask whether the isotopic compositions recorded in secondary sulphides and carbonates of the impactites are inherited from the target, or possibly represent colonization by thermophilic microbes during the post-impact hydrothermal period.

Item Type:Conference Proceedings
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Mark, Dr Darren and Lindgren, Dr Paula and Boyce, Professor Adrian and Lee, Professor Martin
Authors: Simpson, S.L., Boyce, A.J., Lambert, P., Lee, M.R., Mark, D.F., and Lindgren, P.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Copyright Holders:Copyright © 2015 The Authors
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher
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