R7: Petrology, Mineralogy and Economic geology (Joint Session with Society of Resource Geology)

[R7P-04] Compositional variation of talc in thermally metamorphosed serpentinites from SW Japan

Daisuke Miyamoto¹, *Toshio Nozaka¹ (1. Okayama Univ. Sci.)

Keywords:Talc, Prograde metamorphism, Retrograde metamorphism, Peridotite, Serpentinite

To obtain some constraints on the formation conditions for talc, we analyzed chemical compositions of talc and associated minerals in thermally metamorphosed serpentinites from SW Japan. Obtained compositional variations of talc suggest mechanical mixing between phyllosilicates. Talc-chlorite and talc-serpentine mixture looks a characteristic product by prograde and retrograde metamorphism, respectively. Talc itself has a chemical variation suggestive of the replacement of Si by Na and Al in its crystal structure.