Impact-generated hydrothermal systems on Earth and Mars

Gordon R. Osinski*, Livio L. Tornabene, Neil R. Banerjee, Charles S. Cockell, Roberta Flemming, Matthew R. M. Izawa, Jenine McCutcheon, John Parnell, Louisa J. Preston, Annemarie E. Pickersgill, Alexandra Pontefract, Haley M. Sapers, Gordon Southam

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

204 Citations (Scopus)

Abstract

It has long been suggested that hydrothermal systems might have provided habitats for the origin and evolution of early life on Earth, and possibly other planets such as Mars. In this contribution we show that most impact events that result in the formation of complex impact craters (i.e., >2-4 and >5-10. km diameter on Earth and Mars, respectively) are potentially capable of generating a hydrothermal system. Consideration of the impact cratering record on Earth suggests that the presence of an impact crater lake is critical for determining the longevity and size of the hydrothermal system. We show that there are six main locations within and around impact craters on Earth where impact-generated hydrothermal deposits can form: (1) crater-fill impact melt rocks and melt-bearing breccias; (2) interior of central uplifts; (3) outer margin of central uplifts; (4) impact ejecta deposits; (5) crater rim region; and (6) post-impact crater lake sediments. We suggest that these six locations are applicable to Mars as well. Evidence for impact-generated hydrothermal alteration ranges from discrete vugs and veins to pervasive alteration depending on the setting and nature of the system. A variety of hydrothermal minerals have been documented in terrestrial impact structures and these can be grouped into three broad categories: (1) hydrothermally-altered target-rock assemblages; (2) primary hydrothermal minerals precipitated from solutions; and (3) secondary assemblages formed by the alteration of primary hydrothermal minerals. Target lithology and the origin of the hydrothermal fluids strongly influences the hydrothermal mineral assemblages formed in these post-impact hydrothermal systems. There is a growing body of evidence for impact-generated hydrothermal activity on Mars; although further detailed studies using high-resolution imagery and multispectral information are required. Such studies have only been done in detail for a handful of martian craters. The best example so far is from Toro Crater (Marzo, G.A., Davila, A.F., Tornabene, L.L., Dohm, J.M., Fairèn, A.G., Gross, C., Kneissl, T., Bishop, J.L., Roush, T.L., Mckay, C.P. [2010]. Icarus 208, 667-683). We also present new evidence for impact-generated hydrothermal deposits within an unnamed ∼32-km diameter crater ∼350. km away from Toro and within the larger Holden Crater. Synthesizing observations of impact craters on Earth and Mars, we suggest that if there was life on Mars early in its history, then hydrothermal deposits associated with impact craters may provide the best, and most numerous, opportunities for finding preserved evidence for life on Mars. Moreover, hydrothermally altered and precipitated rocks can provide nutrients and habitats for life long after hydrothermal activity has ceased.

Original languageEnglish
Pages (from-to)347-363
Number of pages17
JournalIcarus
Volume224
Issue number2
Early online date1 Oct 2012
DOIs
Publication statusPublished - Jun 2013

Bibliographical note

Acknowledgments
G.R.O. is supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Industrial Research Chair in Planetary Geology sponsored by MDA Space Missions and the Canadian Space Agency (CSA). Funding from the NSERC Discovery Grant, CSA Canadian Analogue Research Network (CARN), the Polar Continental Shelf Project (PSC), and Northern Scientific Training Program (NSTP) programs to various authors provided the resources to carry out field and laboratory-based studies of the hydrothermal systems at the Haughton, Ries, and Sudbury impact structures and is gratefully acknowledged. We thank Susanne Schwenzer and an anonymous reviewer for their detailed and constructive reviews.

Keywords

  • Astrobiology
  • Cratering
  • Impact processes
  • Mars

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