A role for subducted super-hydrated kaolinite in Earth's deep water cycle

Huijeong Hwang, Donghoon Seoung, Yongjae Lee, Zhenxian Liu, Hanns Peter Liermann, Hyunchae Cynn, Thomas Vogt, Chi Chang Kao, Ho Kwang Mao

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Water is the most abundant volatile component in the Earth. It continuously enters the mantle through subduction zones, where it reduces the melting temperature of rocks to generate magmas. The dehydration process in subduction zones, which determines whether water is released from the slab or transported into the deeper mantle, is an essential component of the deep water cycle. Here we use in situ and time-resolved high-pressure/high-temperature synchrotron X-ray diffraction and infrared spectra to characterize the structural and chemical changes of the clay mineral kaolinite. At conditions corresponding to a depth of about 75 km in a cold subducting slab (2.7 GPa and 200 °C), and in the presence of water, we observe the pressure-induced insertion of water into kaolinite. This super-hydrated phase has a unit cell volume that is about 31% larger, a density that is about 8.4% lower than the original kaolinite and, with 29 wt% H2O, the highest water content of any known aluminosilicate mineral in the Earth. As pressure and temperature approach 19 GPa and about 800 °C, we observe the sequential breakdown of super-hydrated kaolinite. The formation and subsequent breakdown of super-hydrated kaolinite in cold slabs subducted below 200 km leads to the release of water that may affect seismicity and help fuel arc volcanism at the surface.

Original languageEnglish
Pages (from-to)947-953
Number of pages7
JournalNature Geoscience
Volume10
Issue number12
DOIs
Publication statusPublished - 2017 Dec 1

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kaolinite
deep water
slab
subduction zone
water
mantle
aluminosilicate
dehydration
clay mineral
seismicity
volcanism
melting
temperature
water content
X-ray diffraction
mineral
rock
cold

All Science Journal Classification (ASJC) codes

  • Earth and Planetary Sciences(all)

Cite this

Hwang, H., Seoung, D., Lee, Y., Liu, Z., Liermann, H. P., Cynn, H., ... Mao, H. K. (2017). A role for subducted super-hydrated kaolinite in Earth's deep water cycle. Nature Geoscience, 10(12), 947-953. https://doi.org/10.1038/s41561-017-0008-1
Hwang, Huijeong ; Seoung, Donghoon ; Lee, Yongjae ; Liu, Zhenxian ; Liermann, Hanns Peter ; Cynn, Hyunchae ; Vogt, Thomas ; Kao, Chi Chang ; Mao, Ho Kwang. / A role for subducted super-hydrated kaolinite in Earth's deep water cycle. In: Nature Geoscience. 2017 ; Vol. 10, No. 12. pp. 947-953.
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Hwang, H, Seoung, D, Lee, Y, Liu, Z, Liermann, HP, Cynn, H, Vogt, T, Kao, CC & Mao, HK 2017, 'A role for subducted super-hydrated kaolinite in Earth's deep water cycle', Nature Geoscience, vol. 10, no. 12, pp. 947-953. https://doi.org/10.1038/s41561-017-0008-1

A role for subducted super-hydrated kaolinite in Earth's deep water cycle. / Hwang, Huijeong; Seoung, Donghoon; Lee, Yongjae; Liu, Zhenxian; Liermann, Hanns Peter; Cynn, Hyunchae; Vogt, Thomas; Kao, Chi Chang; Mao, Ho Kwang.

In: Nature Geoscience, Vol. 10, No. 12, 01.12.2017, p. 947-953.

Research output: Contribution to journalArticle

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