Hydrothermal contributions to global biogeochemical cycles: Insights from the Macquarie Island ophiolite

Hydrothermal alteration of the Macquarie Island ophiolite reveals significant chemical exchanges between ocean crust and seawater, with net fluxes indicating that elements like Si, Ti, Al, and Ca are transferred to the oceans, while H₂O, Mg, Na, K, and S are sequestered in the crust. This study leverages the unique sub-aerial exposure of a complete oceanic crust section to quantify these processes, demonstrating that elemental uptake by veins plays a crucial role for elements like Si, Fe, Mg, and S. The findings suggest that hydrothermal activity could balance riverine inputs of Mg to the oceans, though relationships between spreading rates and chemical exchange fluxes remain poorly understood.

Coggon, R. M., Teagle, D. A. H., Harris, M., Davidson, G. J., Alt, J. C., & Brewer, T. S. (2016). Hydrothermal contributions to global biogeochemical cycles: Insights from the Macquarie Island ophiolite. Lithos, 264, 329–347. https://doi.org/10.1016/j.lithos.2016.08.024