Bayesian probabilistic reconstruction of metamorphic <i>P</i>–<i>T</i> paths using inclusion geothermobarometry

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Author(s)

    • KUWATANI Tatsu
    • Japan Agency for Marine–Earth Science and Technology (JAMSTEC)|PRESTO, Japan Science and Technology Agency (JST)
    • NAGATA Kenji
    • Artificial Intelligence Research Center, National Institute of Advanced Industrial Science and Technology (AIST)|PRESTO, Japan Science and Technology Agency (JST)
    • YOSHIDA Kenta
    • Japan Agency for Marine–Earth Science and Technology (JAMSTEC)
    • OKADA Masato
    • Graduate School of Frontier Sciences, The University of Tokyo

Abstract

<p>Geothermometry and geobarometry are used to study the equilibration of mineral inclusions and their zoned host minerals, which provide information on the <i>P</i>–<i>T</i> conditions of inclusions at the time of their entrapment. However, reconstructing detailed <i>P</i>–<i>T</i> paths remains difficult, owing to the sparsity of inclusions suitable for geothermometry and geobarometry. We developed a stochastic inversion method for reconstructing precise <i>P</i>–<i>T</i> paths from chemically zoned structures and inclusions using the Markov random field (MRF) model, a type of Bayesian stochastic method often used in image restoration. As baseline information for <i>P</i>–<i>T</i> path inversion, we introduce the concepts of pressure and temperature continuity during mineral growth into the MRF model. To evaluate the proposed model, it was applied to a <i>P</i>–<i>T</i> inversion problem using the garnet–biotite geothermometer and the garnet–Al<sub>2</sub>SiO<sub>5</sub>–plagioclase–quartz geobarometer for mineral compositions from published datasets of host garnets and mineral inclusions in pelitic schist. Our method successfully reconstructed the <i>P</i>–<i>T</i> path, even after removing a large part of the inclusion dataset. In addition, we found that by using a probability distribution of the most probable <i>P</i>–<i>T</i> path, rather than a single solution, an objective discussion of the validity of the thermodynamic analysis is possible.</p>

Journal

  • Journal of Mineralogical and Petrological Sciences

    Journal of Mineralogical and Petrological Sciences 113(2), 82-95, 2018

    Japan Association of Mineralogical Sciences

Codes

  • NII Article ID (NAID)
    130006733783
  • Text Lang
    ENG
  • ISSN
    1345-6296
  • Data Source
    J-STAGE 
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