The role of the antigorite + brucite to olivine reaction in subducted serpentinites (Zermatt, Switzerland).

ABSTRACT: Metamorphic olivine formed by the reaction of antigorite + brucite is widespread in serpentinites that crop out in glacier-polished outcrops at the Unterer Theodulglacier, Zermatt. Olivine overgrows a relic magnetite mesh texture formed during ocean floor serpentinization. Serpentinization is associated with rodingitisation of mafic dykes. Metamorphic olivine coexists with magnetite, shows high Mg# of 94-97 and low trace element contents. A notable exception is 4 µg/g Boron (> 10 times primitive mantle), introduced during seafloor alteration and retained in metamorphic olivine. Olivine incorporated 100-140 µg/g H₂O in Si-vacancies, providing evidence for low SiO₂-activity imposed by brucite during olivine growth. No signs for hydrogen loss or major and minor element d

SUBMITTER: Kempf ED 

PROVIDER: S-EPMC7588401 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature