Systematic study of hydrogen incorporation into Fe-bearing wadsleyite and water storage capacity of the transition zone

K. Litasov, E. Ohtani

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)

Abstract

We examined temperature and pressure dependence of hydrogen contents in Fe-bearing wadsleyite at 1200-2000°C and 12-20 GPa using FTIR technique. The samples were synthesized using a multianvil apparatus. The FTIR spectra and calculated H2O contents of Fe-bearing wadsleyite (Mg=88-96) are generally similar with those of Fe-free wadsleyite. The IR spectra are composed of a strong asymmetric band at 3326cm-1 and weak bands at ∼3584, 3611, and 3643cm-1. H2O contents measured in wadsleyite using calibration by Paterson (1982) vary from 0.07 to 2.20 wt.%. We observed clear decrease of H2O contents in wadsleyite with increasing temperature and results at 1600-2000°C are generally consistent with previous data for lower temperatures. It is most likely, that there is no significant effect of pressure on H2O content of wadsleyite. Fe-bearing wadsleyite contains 0.6-0.7 wt.% H2O at 1500°C, which may be close to its water storage capacity along average mantle geotherm in the transition zone. Accordingly, water storage capacity of the average mantle in the transition zone may be estimated as 0.4-0.5 wt.% H2O. The H 2O contents of wadsleyite at 1800-2000°C are 0.07-0.15 wt.%, indicating that it can store significant amount of water even under the hot mantle environments. Temperature dependence of H2O partition coefficient between wadsleyite and olivine (Dwd/ol) may be complex. According to our estimations Dwd/ol decreases with increasing temperature from Dwd/ol=3-4 at 1200°C, reaches a minimum of Dwd/ol≈1.5 at about 1400°C, and than again increases to D wd/fo=2 at 1800-2000°C.

Original languageEnglish
Title of host publicationWater Dynamics - 5th International Workshop on Water Dynamics
Pages113-118
Number of pages6
DOIs
Publication statusPublished - 2008 Mar 17
Event5th International Workshop on Water Dynamics - Sendai, Japan
Duration: 2007 Sep 252007 Sep 27

Publication series

NameAIP Conference Proceedings
Volume987
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

Other5th International Workshop on Water Dynamics
CountryJapan
CitySendai
Period07/9/2507/9/27

Keywords

  • Olivine
  • Transition zone
  • Upper mantle
  • Wadsleyite
  • Water

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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