Monazite petrochronology of the high-pressure granulites of the Carvalhos Klippe

Abstract

Monazite is a robust geochronometer and is widely used for dating high-grade metamorphic events in pelitic and psammitic granulites. Monazite generally displays compositional zoning, and the distribution of trace elements (in particular HREE, Y, and Th) are used to infer its participation in metamorphic reactions. The growth or consumption of monazite can be correlated with the formation or consumption of major metamorphic phases, especially garnet. Monazite petrochronology has been widely used to define crystallization events in high to ultra-high-temperature rocks. However, the behavior of monazite in high-pressure rocks is still poorly understood, which reinforces the need to investigate monazite in rocks formed under high-pressure regimes (>12 kbar). This work aims to apply monazite petrochronology in the high-pressure felsic granulites of the Carvalho's Klippe (Southern Brasilia Orogen), to recognize the stages of progressive and retrograde monazite growth and to correlate the compositional domains to the obtained ages, in order to investigate the timescales involved in the metamorphic processes related to high-pressure metamorphism in the Neoproterozoic.(AU)