Water transfer to the deep mantle through hydrous, Al-rich silicates in subduction zones

Hermann, Jörg; Lakey, Shayne (2021). Water transfer to the deep mantle through hydrous, Al-rich silicates in subduction zones. Geology, 49(8), pp. 911-915. Geological Society of America 10.1130/g48658.1

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Constraining deep-water recycling along subduction zones is a first-order problem to understand how Earth has maintained a hydrosphere over billions of years that created conditions for a habitable planet. The pressure-temperature stability of hydrous phases in conjunction with slab geotherms determines how much H2O leaves the slab or is transported to the deep mantle. Chlorite-rich, metasomatic rocks that form at the slab-mantle interface at 50–100 km depth represent an unaccounted, H2O-rich reservoir in subduction processes. Through a series of high-pressure experiments, we investigated the fate of such chlorite-rich rocks at the most critical conditions for subduction water recycling (5–6.2 GPa, 620–800 °C) using two different natural ultramafic compositions. Up to 5.7 GPa, 740 °C, chlorite breaksdown to an anhydrous peridotite assemblage, and H2O is released. However, at higher pressures and lower temperatures, a hydrous Al-rich silicate (11.5 Å phase) is an important carrier to enable water transfer to the deep mantle for cold subduction zones. Based on the new phase diagrams, it is suggested that the deep-water cycle might not be in secular equilibrium.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences > Petrology
08 Faculty of Science > Institute of Geological Sciences

UniBE Contributor:

Hermann, Jörg

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

0091-7613

Publisher:

Geological Society of America

Language:

English

Submitter:

Jörg Hermann

Date Deposited:

24 Mar 2022 16:06

Last Modified:

24 Mar 2022 16:06

Publisher DOI:

10.1130/g48658.1

BORIS DOI:

10.48350/167895

URI:

https://boris.unibe.ch/id/eprint/167895

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