Boron isotope record of peak metamorphic ultrahigh-pressure and retrograde fluid-rock interaction in white mica (Lago di Cignana, Western Alps).

ABSTRACT: This study presents boron (B) concentration and isotope data for white mica from (ultra)high-pressure (UHP), subduction-related metamorphic rocks from Lago di Cignana (Western Alps, Italy). These rocks are of specific geological interest, because they comprise the most deeply subducted rocks of oceanic origin worldwide. Boron geochemistry can track fluid-rock interaction during their metamorphic evolution and provide important insights into mass transfer processes in subduction zones. The highest B contents (up to 345 μg/g B) occur in peak metamorphic phengite from a garnet-phengite quartzite. The B isotopic composition is variable (δ11B = - 10.3 to - 3.6%) and correlates positively with B concentrations. Based on similar textures and major element mica composition, neither textural differ

SUBMITTER: Halama R 

PROVIDER: S-EPMC7010363 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature