Abstract Sanukitoid rocks make up a complete magmatic series with distinct geochemical characteristics of TTG suites and granitoids from modern magmatic arcs and are regarded as markers of the transition from typically Archean geodynamics to modern plate tectonics. Although most known sanukitoid suites formed during the Neoarchean and Mesoarchean, numerous papers have characterized Paleoproterozoic magmatic arc granitoid rocks showing affinity with the sanukitoid series. This work presents new data from field, lithogeochemistry, zircon U-Pb geochronology, and Sm-Nd and Sr isotopic studies on granodioritic granulites with sanukitoid signatures from the Juiz de Fora Complex (JFC), one of the Paleoproterozoic tectonic components of the Minas-Bahia Orogenic System (MBOS), southern São Francisco Paleocontinent (southeastern Brazil). These rocks crystallized at ~2175 Ma and present values of εNdt between −4.0 and +0.5, TDM between 2.57 and 2.12 Ga, and 87Sr/86Sri between 0.6937 and 0.7137. We interpret these rocks as the result of crystallization of magmas from a hybrid mantle source extensively contaminated by crustal material during protracted subduction. In southeastern São Francisco Paleocontinent, the association of sanukitoid rocks with other magmatic arc rocks points to a complex and prolonged Rhyacian accretionary system similar to modern plate tectonics.

Abstract The Acaiaca Complex (AC) is located in southeastern Minas Gerais state, and comprises felsic, mafic, ultramafic, and aluminous granulites as well as lower grade gneisses and mylonites. The complex is distributed over an area of ca. 36 km by 6 km, surrounded by amphibolite facies gneisses of the Mantiqueira Complex (MC). The discrepancy in the metamorphic grade between both complexes led to the present study aiming to understand the metamorphic history of the AC by means of geothermobarometric calculations and electron microprobe Th-U-Pb monazite dating. Estimates of the metamorphic conditions of the granulites based on conventional geothermobarometry and THERMOCALC resulted in temperatures around 800 ºC and pressures between of 5.0 and 9.9 kbar and a retrometamorphic path characterized by near-isobaric cooling. Part of the granulites was affected by anatexis. The melting of felsic granulites resulted in the generation of pegmatites and two aluminous lithotypes. These are: i) garnet-sillimanite granulite with euhedral plagioclase and cordierite that show straight faces against quartz, and is the crystallization product of an anatectic melt, and ii) garnet-kyanite-cordierite granulite, which is probably the restite of anatexis, as indicated by textures and high magnesium contents. Th-U-Pb monazite geochronology of two granulite samples resulted in a metamorphic age around 2060 Ma, which is similar to the age of the MC registered in the literature. The similar Paleoproterozoic metamorphic ages of both complexes lead to the conclusion that the Acaiaca Complex may be the high grade metamorphic unit geochronologically related to the lower grade Mantiqueira Complex.