The discovery of Lake Hephaestus, the youngest athalassohaline deep-sea formation on Earth

Violetta La Cono, Giovanni Bortoluzzi, Enzo Messina, Gina La Spada, Francesco Smedile, Laura Giuliano, Mireno Borghini, Christine Stumpp, Philippe Schmitt-Kopplin, Mourad Harir, William K. O’Neill, John E. Hallsworth, Michail Yakimov*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)
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Hydrated, magnesium-rich minerals and subglacial brines exist on the martian surface, so the habitability of high-Mg2+ environments on Earth has extraterrestrial (as well as terrestrial) implications. Here, we report the discovery of a MgCl2-dominated (4.72 M) brine lake on the floor of the Mediterranean Ridge that underlies a 3500-m water column, and name it Lake Hephaestus. Stable isotope analyses indicated that the Hephaestus brine is derived from interactions between ancient bishofite-enriched evaporites and subsurface fluids. Analyses of sediment pore waters indicated that the Hephaestus depression had contained the MgCl2 brine for a remarkably short period; only 700 years. Lake Hephaestus is, therefore, the youngest among currently known submarine athalassohaline brine lakes on Earth. Due to its biologically hostile properties (low water-activity and extreme chaotropicity), the Hephaestus brine is devoid of life. By contrast, the seawater-Hephaestus brine interface has been shown to act as refuge for extremely halophilic and magnesium-adapted stratified communities of microbes, even at MgCl2 concentrations that approach the water-activity limit for life (0.653).

Original languageEnglish
Article number1679
Number of pages11
JournalScientific Reports
Issue number1
Early online date08 Feb 2019
Publication statusPublished - 01 Dec 2019

ASJC Scopus subject areas

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