Heterogeneity in syntectonic granitoids emplaced in a major shear zone, southern Brazil

摘要

Two granitoid associations were emplaced during the development of the Major Gercino Shear Zone in eastern Santa Catarina, southern Brazil. The 614 Ma Fernandes Granitoid Association is composed mainly of hornblende syenogranites including A-type, and alkali-calcic and calc-alkaline types. Initial Sr isotope ratios are heterogeneous, but systematic isotopic and element variations suggest that different source rocks produced magmas which underwent mixing and fractional crystallization. The Rolador Granitoid Association of biotite-bearing granodiorite is less isotopically heterogeneous, but systematic isotopic and element variations are not obvious.