Notícies



First findings of the link between faults and water entering the Earth during tectonic activity


Schematic illustrating serpentinization (in green) associated with a single normal fault ‘F obtained from the model of velocity distribution. Picture: Nature Geoscience
11 Març 2016

An international team led by the University of Southampton (UK) and with the participation of César Ranero, ICREA researcher at the Department of Marine Geosciences of the ICM has found that the tectonic faults control the amount of water entering the Earth at depths of several kilometers. The findings, published in the journal Nature Geoscience, have large-scale implications since the reaction between seawater (hydrosphere) and rocks (litosphere) at great depth causes a geochemical exchange, which also produces energy and nutrients that can be used by various anaerobic ecosystems.

The scientists conducted experiments on the continental margin west of Iberian peninsula. There, faults were formed when continents of North America from Europe separated from each other, around 120 million years ago. The work is based on the use of sound waves to determine the distribution of serpentinite, a mineral that forms when seawater comes into contact with deep peridotite rocks, under the Earth's crust.

"The results show that the amount of serpentinite formed at the base of each fault is proportional to the displacement on that fault, which in turn is related to the duration of tectonic activity," says César Ranero.

The study also estimated the average rate at which sea water enters the mantle through faults. "This rate is comparable to that estimated for water circulation in hot rocks in the ocean ridges, where anaerobic life is common", concludes Ranero.

Paper

G. Bayrakci1, T. A. Minshull, D. S. Sawyer, T. J. Reston, D. Klaeschen, C. Papenberg, C. Ranero, J. M. Bull, R. G. Davy, D. J. Shillington, M. Perez-Gussinye, J. K. Morgan. "Fault-controlled hydration of the upper mantle". Nature Geoscience. doi:10.1038/ngeo2671