Oxygen consumption rates in subseafloor basaltic crust derived from a reaction transport model

• Published in: Nature communications Vol. 4; no. 1; p. 2539
• Main Authors: Orcutt, Beth N., Wheat, C. Geoffrey, Rouxel, Olivier, Hulme, Samuel, Edwards, Katrina J., Bach, Wolfgang
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 2013; Nature Publishing Group
• Subjects: 704/158/47; 704/172/169/827; Atlantic Ocean; Biomass; Diffusion; Geologic Sediments - chemistry; Humanities and Social Sciences; Models, Statistical; multidisciplinary; Oxygen - chemistry; Science; Science (multidisciplinary); Sciences of the Universe; Silicates; Strontium - analysis; Strontium Isotopes; Atlantic Ocean
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms3539

Oceanic crust is the largest potential habitat for life on Earth and may contain a significant fraction of Earth’s total microbial biomass; yet, empirical analysis of reaction rates in basaltic crust is lacking. Here we report the first assessment of oxygen consumption in young (~8 Ma) and cool (<25 °C) basaltic crust, which we calculate from modelling dissolved oxygen and strontium pore water gradients in basal sediments collected during Integrated Ocean Drilling Program Expedition 336 to ‘North Pond’ on the western flank of the Mid-Atlantic Ridge. Dissolved oxygen is completely consumed within the upper to middle section of the sediment column, with an increase in concentration towards the sediment–basement interface, indicating an upward supply from oxic fluids circulating within the crust. A parametric reaction transport model of oxygen behaviour in upper basement suggests oxygen consumption rates of 1 nmol cm
−3
ROCK
d
−1
or less in young and cool basaltic crust.
Deep oceanic crust could host a wealth of microbial life, but biogeochemical reactions therein are poorly understood. Orcutt
et al.
combine measurements of sedimentary oxygen and pore water chemistry from basement crust with a reactive transport box model to shed light on oxygen consumption in basaltic crust.