ZINCIAN STAUROLITE IN METABASITES AND METAPELITES FROM THE BETIC-CORDILLERA (SE SPAIN)

Zn-rich staurolite is found in both metabasites of the Nevado-Filabrid e Complex and carpholite-bearing metapelites of the Alpujarride Comple x of the Betic Cordillera, Spain. Staurolite from the metabasites has the highest Zn contents described for natural samples, up to 13.21 wt % ZnO. Staurolite from the metabasite is a Zn-dominant staurolite (av. X(Zn) = 0.48, X(Fe) = 0.28, X(Mg) = 0.25); staurolite from the metape lite is a Fe-dominant staurolite with Zn (av. X(Fe) = 0.49, X(Zn) = 0. 30, X(mg) = 0.21) A remarkable Zn and Fe zoning characterizes both sam ples. Breakdown of staurolite produces either gahnite + hematite + qua rtz or chlorite with fine intergrowths of margarite + paragonite in th e metabasite and metapelite staurolite respectively. Principal compone nts analysis suggests that the main substitution operating at the Al d ominant sires is Al-vi reversible arrow (Zn, Mg) and Al-vi reversible arrow (Mg, Fe) for the metabasite and metapelite staurolites respectiv ely. At the Fe dominant sites the main substitution in both could be F e reversible arrow Zn. The PT fields of both parageneses with zincian staurolites suggest qualitatively, that the lower temperature stabilit y is less than that proposed for the iron staurolite (T < 450 degrees C in both cases).