Influence of high marine Ca/SO4 ratio on alteration of submarine basalts at 2.41 Ga documented by triple O and Sr isotopes of epidote ...

• Main Authors: Zakharov, David O., Lundstrom, Craig C., Laurent, Oscar, Reed, Mark H., Bindeman, Ilya N.
• Format: Article in Journal/Newspaper
• Language: English
• Published: ETH Zurich 2021
• Subjects: Triple oxygen isotopes; Marine sulfate; Altered oceanic crust; Epidote; Mineral-aqueous equilibrium modeling; karelia*
• Online Access: https://dx.doi.org/10.3929/ethz-b-000478764; http://hdl.handle.net/20.500.11850/478764

Over the course of Earth’s history, marine sulfate concentrations have been increasing in response to long-term atmospheric oxygenation. In contrast to modern oceans, where abundant sulfate precipitates in hot oceanic crust as anhydrite, Precambrian oceans contained much less (~0–10 mM) sulfate, so that submarine hydrothermal systems were comparatively poor in anhydrite. As a step towards exploring the role of chemical evolution of seawater solutes, we investigate the reaction between basalt and seawater that took place at the ca. 2.43–2.41 Ga Vetreny Belt (Karelia craton, NW Russia) using fluid inclusion and multi-isotope measurements complemented by reactive transport and static aqueous-mineral equilibrium calculations. Using fluid inclusion measurements by LA-ICP-MS, we constrain the Sr concentration in the least modified seawater-derived fluids and address the effect of phase separation. Then, we complement the previous δ18O – Δ′17O datasets with new 87Sr/86Sr measurements performed on 2.41 Ga epidote ... : Precambrian Research, 358 ...