Zoisite-Clinozoisite Relations in Low- to Medium-Grade High-Pressure Metamorphic Rocks and Their Implications

Masaki Enami and Shohei Banno
Department of Earth Sciences, Nagoya University, Nagoya 464, Japan
Department of Earth Sciences, Kanazawa University, Kanazawa 920, Japan

Summary: Coexisting zoisite and clinozoisite in seventeen specimens from six localities in Japan have been studied with the electron-probe microanalyser. Zoisite and clinozoisite are commonly zoned, but compositional gaps between them are systematic. Referring to the metamorphic grade of the host rocks, a temporary and schematic phase-diagram for the system Ca2Al3Si3O12-(OH)-Ca2Al2Fe3+Si3O12(OH) is presented. With increasing temperature, in the range of low- to medium-grade metamorphism, the compositional gap between the two epidote-group minerals shifts towards higher Fe3+ compositions.

Mineralogical Magazine; December 1980 v. 43; no. 332; p. 1005-1013; DOI: 10.1180/minmag.1980.043.332.08
© 1980, The Mineralogical Society
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