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- Title
A role for subducting clays in the water transportation into the Earth's lower mantle.
- Authors
Bang, Yoonah; Hwang, Huijeong; Liermann, Hanns-Peter; Kim, Duck Young; He, Yu; Jeon, Tae-Yeol; Shin, Tae Joo; Zhang, Dongzhou; Popov, Dmitry; Lee, Yongjae
- Abstract
Subducting sedimentary layer typically contains water and hydrated clay minerals. The stability of clay minerals under such hydrous subduction environment would therefore constraint the lithology and physical properties of the subducting slab interface. Here we show that pyrophyllite (Al2Si4O10(OH)2), one of the representative clay minerals in the alumina-silica-water (Al2O3-SiO2-H2O, ASH) system, breakdowns to contain further hydrated minerals, gibbsite (Al(OH)3) and diaspore (AlO(OH)), when subducts along a water-saturated cold subduction geotherm. Such a hydration breakdown occurs at a depth of ~135 km to uptake water by ~1.8 wt%. Subsequently, dehydration breakdown occurs at ~185 km depth to release back the same amount of water, after which the net crystalline water content is preserved down to ~660 km depth, delivering a net amount of ~5.0 wt% H2O in a phase assemblage containing δ-AlOOH and phase Egg (AlSiO3(OH)). Our results thus demonstrate the importance of subducting clays to account the delivery of ~22% of water down to the lower mantle. The breakdown of pyrophyllite, a hydrous clay mineral in the oceanic sediment, into further hydrated minerals during cold subduction may account for some 22% of water delivered to the lower mantle.
- Subjects
EARTH'S mantle; MARITIME shipping; GIBBSITE; CLAY; SUBDUCTION
- Publication
Nature Communications, 2024, Vol 15, Issue 1, p1
- ISSN
2041-1723
- Publication type
Article
- DOI
10.1038/s41467-024-48501-z