Vesuvianite and Associated Skarn Minerals in the Shiraishizawa Area, Tanzawa Mountainland, Central Japan

概要

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Data are presented on the chemical compositions and cell parameters of vesuvianite and associated skarn minerals in the metamorphosed limestones of the Shiraishizawa area, Tanzawa mountainland, Kanagawa Prefecture, Central Japan. The vesuvianites show narrow but significant compositional variations within individual grains and between samples analysed. The Al_2O_3 content ranges from 14.96 to 16.61 wt. % apparently correlated with the variation of the Fe_2O_3^T content (3.35-5.61wt. %). In addition, the TiO_2 content varies in a relatively wide range (0.72-2.79wt. %). The vesuvianites are characterized by excess Y site cations (over 13.0 per formula unit) as well as high Ca (over 19.0 per formula unit) in the anhydrous structural formulae based on 74 oxygens. The mineral parageneses and modal mineral compositions suggest that the mineral associations in the vesuvianite-bearing rocks can be represented by an equation: Grossular+Monticellite+Calcite+H_2O=Vesuvianite+CO_2. The data also suggest an involvement of metasomatic processes in the skarn formation. Moving aqueous fluids from the quartzdiorite magma into the limestones might transfer some elements (Mg, Fe, Al and Si) as well as heat and stabilized vesuvianite in the zones adjacent to the intrusive.
横浜国立大学の論文
1989-10-31