New finding of paragonite–clinozoisite association in garnet from the type locality of Sanbagawa belt (Kanto Mountains, Japan)

Paragonite–clinozoisite associated within garnets (pyrope2–7 almandine60–64 grossular10–28 spesartine1–10) was newly found in the type locality of the Sanbagawa schist in the Kanto Mountains, Japan. The composite inclusions were confirmed in prograde–zoned garnet porphyroblasts in garnet–zone metapelites that have a typical pelitic whole–rock composition (Mn/Fe = 0.019, Mg/Fe = 0.381). The garnets also contain mineral inclusions of quartz, albite, phengite, chlorite, rutile, calcite, apatite, and zircon. Phengite in the metapelite yielded a K–Ar age of 67.3 ± 1.6 Ma as the younger part of the Sanbagawa schist in this region. This paragonite–clinozoisite association provides a mineralogical index of high pressure (P)–temperature (T) metamorphism of the type locality of the Sanbagawa schist. Moreover, the clinozoisite–paragonite composite inclusions within prograde–zoned garnets suggest a prograde P–T path from the stability of lawsonite and albite.