Celebrating the Centenary of “The Geology of Central Minas Gerais, Brazil”: An Insight from the Sítio Largo Amphibolite

Abstract

AbstractOne century ago, in 1915, Harder and Chamberlin established the stratigraphy on which the geology of the Quadrilatero Ferrifero of Minas Gerais is based. One of their key observations was the occurrence of metavolcanic rocks in spatial association with the Itabira iron formation, an observation that has been ignored by most authors. Crucial for the understanding of the geology of the Quadrilatero Ferrifero, but equally ignored, is a 400-m-thick unit of amphibolite that rests immediately on the Itabira iron formation, also known as the Caue Itabirite. Here, we revitalize the Sitio Largo amphibolite by indicating its basaltic affiliation. We present new results of U-Pb dating of zircon and rutile that show that the amphibolite protolith, which covered an erosional surface on the Caue Itabirite, is ca. 2.18 Ga old and underwent metamorphic overprint at ca. 500 Ma.