Chafalote Metamorphic Suite (Uruguay): Reflections on the evolution of the Punta del Este Terrane

The Chafalote Metamorphic Suite, located in the Uruguayan sector of the Punta del Este Terrane, southeasternmost Dom Feliciano Belt, comprises semipelitic, migmatitic metapelites, mafic granulites, and calc-silicate/amphibolitic gneisses. These supracrustal rocks occur as roof pendants in a granodiorite belonging to the Cerro Olivo Complex. The main structure of the Chafalote Metamorphic Suite is a composite S-0/S-1 banding, related to the main deformation event (D-1) developed under upper-amphibolite/granulite fades conditions. This work presents an integrated study on the latter rocks, involving different geochronological methods (monazite U-Pb LA-ICP-MS and zircon U-Pb SHRIMP) and whole rock Sm-Nd isotope data in order to better understand the metamorphic evolution of the Chafalote Metamorphic Suite during the amalgamation of the SW Gondwana paleocontinent in thi Neoproterozoic. The studied rocks record a peak metamorphic event (M-2) occurred at around 660 Ma (monazite U-Pb ages), which was followed by decompression and partial melting (M-3 event) at around 640 Ma (zircon U-Pb ages), probably during the late stages of the D-1 event. The retrograde methamorphic event (M-4) is related to the transition between the D-1 and the development of NE-SW striking, lowgrade sinistral shear zones (D-2 event) and intrusion of syn-to post-orogenic Brasiliano granitoids of the Aigua Batholith at around 600 Ma. The metamorphic conditions, together with geochronological and isotopic similarities, allow the correlation between the studied high-grade metasedimentary rocks and those from the Paso del Dragon Complex in Uruguay, and from the Virzea do Capivarita, Arroio Grande, and Telho Complex in Brazil. The latter rocks possibly share similar source areas and represent different portions of the Neoproterozoic fore-arc and/or back-arc basins developed in the Dom Feliciano Belt during the Brasiliano/Pan-African orogenic cycle.