Anoxic Weathering Of Mafic Oceanic Crust Promotes Atmospheric Oxygenation
Phosphorus is an essential element for all known life, and the global phosphorus cycle is widely believed to be a key factor limiting the extent of Earth’s biosphere.
The size and scope of any biosphere beyond our solar system is similarly likely to be limited by the planetary cycling of bioavailable phosphorus. Continental weathering has long been considered to be the only source of bioavailable phosphorus to the oceans, with submarine hydrothermal processes acting as a phosphorus sink. This opens up the possibility of severe phosphorus limitation on the early Earth prior to the widespread emergence of continental crust above sea level, and further implies that a common class of volatile-rich habitable exoplanet – so called ‘waterworlds’ – may be biological deserts.
However, this framework is based on the behavior of phosphorus in modern hydrothermal systems interacting with pervasively oxygenated deep oceans. Here, we present new experimental results indicating that abiotic carbon dioxide sequestration during anoxic basalt alteration is an efficient source of bioavailable phosphorus. Placing these observations into the context of a simple model of planetary phosphorus-carbon-oxygen mass balance, we suggest that volatile-rich Earth-like planets lacking exposed continents may actually be more likely than Earth to develop robust biospheres that can lead to remotely detectable atmospheric biosignatures.
Drew D. Syverson, Christopher T. Reinhard, Terry T. Isson, Cerys Holstege, Joachim Katchinoff, Benjamin M. Tutolo, Barbara Etschmann, Joël Brugger, Noah J. Planavsky
(Submitted on 18 Feb 2020)
Comments: Manuscript under consideration in Earth and Planetary Science Letters
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2002.07667 [astro-ph.EP] (or arXiv:2002.07667v1 [astro-ph.EP] for this version)
Submission history
From: Christopher Reinhard
[v1] Tue, 18 Feb 2020 15:58:11 UTC (6,404 KB)
https://arxiv.org/abs/2002.07667
Astrobiology
