S2: Water Rock Interaction (Special Session)

[S2P-03] LILE mobility at each metamorphic stage recorded in the Sanbagawa metamorphic belt: Application of Protolith Reconstruction Model

[Presentation award entry]

*Satoshi Matsuno¹, Masaoki Uno¹, Atsushi Okamoto¹, Noriyoshi Tsuchiya¹ (1. Tohoku Univ. Env.)

Keywords:Fluid-rock interaction, Protolith reconstruction, Metamorphic rock, Subduction-related metamorphism

Elemental transfer during prograde and retrograde metamorphism was revealed for metabasaltic rocks of the Sanbagawa metamorphic belt. The elemental transfer was quantified by a novel “Protolith Reconstruction Model” that estimate protolith compositions by machine-learning algorithms trained with global basalt compositional datasets. The results indicate that prograde and retrograde metamorphisms caused systematic depletion and enrichment in Rb, Ba, K, and Sr, respectively.