The Eclogite-Garnetite transformation in the MORB + H2O system

Kazuaki Okamoto; Shigenori Maruyama

doi:10.1016/j.pepi.2003.07.029

The Eclogite-Garnetite transformation in the MORB + H₂O system

Kazuaki Okamoto, Shigenori Maruyama

Research output: Contribution to journal › Article › peer-review

73 Citations (Scopus)

Abstract

To decipher phase relations of oceanic crust in the coldest slab at the mantle transition zone, multi-anvil experiments were conducted in the MORB+H₂O system at pressures of 10-19 GPa, and temperatures of 700-1500 °C. Garnet and stishovite were recognized in all run charges. Above 15 GPa, garnet drastically increases NaSi (Na₂MSi₅O₁₂) component (M = Ca, Mg, Fe²⁺), jadeite occurs instead of omphacite. Na-, K-hollandite containing 7 mol% NaAlSi₃O₈ and Ca-perovskite with 60 mol% CaTiO₃, were observed at P> 17 GPa. With decomposition of omphacite and increase of modal ratio of garnet, there is a sharp increase of density at 440 km. The density increase due to appearance of Ca-perovskite at 570 km, is estimated approximately 100 km shallower than that of previous estimation.

Original language	English
Pages (from-to)	283-296
Number of pages	14
Journal	Physics of the Earth and Planetary Interiors
Volume	146
Issue number	1-2
DOIs	https://doi.org/10.1016/j.pepi.2003.07.029
Publication status	Published - Aug 16 2004

Keywords

Ca-perovskite
Eclogite-garnetite transformation
Jadeite
Na(Ca,Mg,Fe SiO-component in garnet
UHP experiments

ASJC Scopus subject areas

Astronomy and Astrophysics
Geophysics
Physics and Astronomy (miscellaneous)
Space and Planetary Science

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title = "The Eclogite-Garnetite transformation in the MORB + H2O system",

abstract = "To decipher phase relations of oceanic crust in the coldest slab at the mantle transition zone, multi-anvil experiments were conducted in the MORB+H2O system at pressures of 10-19 GPa, and temperatures of 700-1500 °C. Garnet and stishovite were recognized in all run charges. Above 15 GPa, garnet drastically increases NaSi (Na2MSi5O12) component (M = Ca, Mg, Fe2+), jadeite occurs instead of omphacite. Na-, K-hollandite containing 7 mol% NaAlSi3O8 and Ca-perovskite with 60 mol% CaTiO3, were observed at P> 17 GPa. With decomposition of omphacite and increase of modal ratio of garnet, there is a sharp increase of density at 440 km. The density increase due to appearance of Ca-perovskite at 570 km, is estimated approximately 100 km shallower than that of previous estimation.",

keywords = "Ca-perovskite, Eclogite-garnetite transformation, Jadeite, Na(Ca,Mg,Fe SiO-component in garnet, UHP experiments",

author = "Kazuaki Okamoto and Shigenori Maruyama",

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AU - Okamoto, Kazuaki

AU - Maruyama, Shigenori

PY - 2004/8/16

Y1 - 2004/8/16

N2 - To decipher phase relations of oceanic crust in the coldest slab at the mantle transition zone, multi-anvil experiments were conducted in the MORB+H2O system at pressures of 10-19 GPa, and temperatures of 700-1500 °C. Garnet and stishovite were recognized in all run charges. Above 15 GPa, garnet drastically increases NaSi (Na2MSi5O12) component (M = Ca, Mg, Fe2+), jadeite occurs instead of omphacite. Na-, K-hollandite containing 7 mol% NaAlSi3O8 and Ca-perovskite with 60 mol% CaTiO3, were observed at P> 17 GPa. With decomposition of omphacite and increase of modal ratio of garnet, there is a sharp increase of density at 440 km. The density increase due to appearance of Ca-perovskite at 570 km, is estimated approximately 100 km shallower than that of previous estimation.

AB - To decipher phase relations of oceanic crust in the coldest slab at the mantle transition zone, multi-anvil experiments were conducted in the MORB+H2O system at pressures of 10-19 GPa, and temperatures of 700-1500 °C. Garnet and stishovite were recognized in all run charges. Above 15 GPa, garnet drastically increases NaSi (Na2MSi5O12) component (M = Ca, Mg, Fe2+), jadeite occurs instead of omphacite. Na-, K-hollandite containing 7 mol% NaAlSi3O8 and Ca-perovskite with 60 mol% CaTiO3, were observed at P> 17 GPa. With decomposition of omphacite and increase of modal ratio of garnet, there is a sharp increase of density at 440 km. The density increase due to appearance of Ca-perovskite at 570 km, is estimated approximately 100 km shallower than that of previous estimation.

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KW - Na(Ca,Mg,Fe SiO-component in garnet

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