Abstract
A U-Pb SHRIMP zircon geochronological study was carried out in the Nico Pérez Terrane in the central-eastern portion of Uruguay with the aim of constraining its geological evolution and its cratonic affinity. Nico Pérez Terrane is made up by a mosaic of tectonic blocks with diferente lithologies and sizes. This terrane is limited to the west by the Piedra Alta Terrane through the Sarandí del Yí shear zone, and to the east, is in tectonic contact through the Retamosa thrust with the Dom Feliciano Belt (Brasiliano orogenic cycle). Lithologically, the Nico Pérez Terrane is composed by medium to high grade metamorphic rock contained in three tectonic blocks (Pavas, Valentines and Rivera blocks) represented mainly by granitoids, as well as ortho and parametamorphic rocks, such as amphibolites, metapyroxenites, BIFs, schists, quartzites with fuchsite, among others. Archean inheritance, Rhyacian, Statherian, and Neoproterozoic magmatic ages are reported here. Similar ages, which show Archaean inheritance and Neoproterozoic imprint, reported in units of the Piedra Alta Terrane modify the idea that the Río de La Plata Craton only corresponds to a juvenile Paleoproterozoic tectonic unit. This, together with recently published geophysical information, supports the cratonic affinity of the Nico Pérez Terrane with the Río de La Plata Craton.
Highlights
The Nico Pérez Terrane, located in the central portion of Uruguay (Fig. 1), records the oldest basement ages of the region. Bossi and Campal (1992) identified this terrane from the main outcropping areas of the Río de La Plata Craton and based on lithological and structural data they defined it as a Paleoproterozoic block affected by tectono-magmatic events related to the Brasiliano-Panafrican orogenic cycle
Similar ages, which show Archaean inheritance and Neoproterozoic imprint, reported in units of the Piedra Alta Terrane modify the idea that the Río de La Plata Craton only corresponds to a juvenile Paleoproterozoic tectonic unit
New U-Pb SHRIMP zircon results on eight samples of granitoid rocks are presented in this work with the goal of constraining the tectonic evolution of the Nico Pérez Terrane
Summary
The Nico Pérez Terrane, located in the central portion of Uruguay (Fig. 1), records the oldest basement ages of the region. Bossi and Campal (1992) identified this terrane from the main outcropping areas of the Río de La Plata Craton (sensu Almeida et al, 1973) and based on lithological and structural data they defined it as a Paleoproterozoic block affected by tectono-magmatic events related to the Brasiliano-Panafrican orogenic cycle. Bossi and Campal (1992) identified this terrane from the main outcropping areas of the Río de La Plata Craton (sensu Almeida et al, 1973) and based on lithological and structural data they defined it as a Paleoproterozoic block affected by tectono-magmatic events related to the Brasiliano-Panafrican orogenic cycle. These authors postulated that the Nico Pérez Terrane represents the foreland of the Neoproterozoic orogenic belt known as Dom Feliciano Belt (Fragoso-César, 1980). Oriolo et al (2016a, 2017) interpreted this terrane as a basement inlier of the Dom Feliciano Belt, and they suggested its affinity with the West Africa Congo Craton based on tectonostratigraphy, U-Pb ages, and Hf isotopic data
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