The Neoproterozoic basement of the Sauce Chico Inlier (Ventania System): Geochemistry and U–Pb geochronology of igneous rocks with African lineage in central-eastern Argentina

• Autores: Ballivián Justiniano, Carlos A.; Basei, Miguel A.; Sato, Ana Maria; González, Pablo Diego; Benítez, Manuela; Lanfranchini, Mabel
• Año de publicación: 2020
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Ciencias Exactas y Naturales; LA-ICP-MS U–Pb Zircon Dating; Sm–Nd isotope data; Sierra de la Ventana Belt; Dom Feliciano Belt; Gariep Belt; Ciencias Exactas y Naturales
• Institución: Universidad Nacional de Río Negro

Fil: Ballivián Justiniano, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Instituto de Recursos Minerales (INREMI), Universidad Nacional de La Plata–Comisión de Investigaciones Científicas de la Provincia de Buenos Aires; Argentina.
Fil: Basei, Miguel. Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). Centro de Pesquisas Geocronológicas (CPGeo), Instituto de Geociências, Universidade de São Paulo, Cidade Universitária; Brasil.
Fil: Sato, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas; Argentina.
Fil: González, Pablo Diego. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Instituto de Investigación en Paleobiología y Geología (IIPG), Universidad Nacional de Río Negro–CONICET; Argentina.
Fil: Benítez, Manuela. Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC). Instituto de Recursos Minerales (INREMI), Universidad Nacional de La Plata–CIC; Argentina.
Fil: Lanfranchini, Mabel. Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC). Instituto de Recursos Minerales (INREMI), Universidad Nacional de La Plata–CIC; Argentina.
This study describes the geology, geochemistry, and LA-ICP-MS U–Pb geochronology of igneous rocks that crop out in the Sauce Chico Inlier (SCI) and constitute the Neoproterozoic basement of the Ventania System, Argentina. Magmatism registered in the SCI has developed in two phases. The first phase, of Tonian age, is represented by rift-related calc-alkaline and alkaline granites with ages of 783.8 ± 3.7 Ma (εNd(t)=−7.20) and 776.5 ± 4.7 Ma (εNd(t) = +1.65), respectively. This phase would be related to the break-up of the Rodinia supercontinent and subsequent opening of the Adamastor Ocean. In the Dom Feliciano Belt of southern Brazil and eastern Uruguay, the Tonian magmatism is represented in the Cerro Olivo Complex of the Punta del Este Terrane and in basement inliers of the Pelotas Batholith. The second phase, of Ediacaran age, started with the intrusion of syn-orogenic calc-alkaline granites (620.8 ± 5.8 Ma and 620.3 ± 2.5 Ma; εNd(t)=−9.94/−9.18) and continued with the extrusion of post-orogenic alkaline (577.3 ± 3.9 Ma; εNd(t)=−6.29) and calc-alkaline (543.6 ± 4.0 Ma; εNd(t)=−3.38) acid volcanic rocks. This phase would be related to the closure of the Adamastor Ocean, generation of a magmatic arc along the western margin of the Kalahari Craton, and collision between this and the Río de la Plata Craton. A post-collisional magmatism would have developed due to orogenic collapse (< 580 Ma). With the exception of the Tonian alkaline granite, in the remaining SCI igneous rocks, the juvenile component becomes more important as the crystallization age decreases. The available Nd model ages are between 1.80 and 1.14 Ga and suggest a mixing of older crust with juvenile material. The tectonic evolution of the Ventania System basement is consistent with that observed in the Dom Feliciano Belt and its African counterparts. We present here the first evidence of Tonian magmatism in the Ventania System basement. The results presented here also confirm those obtained previously by other authors. Zircon cores from the SCI igneous rocks have U–Pb inherited ages between ca. 1200 and 900 Ma that could be indicative of a lineage with the Gariep Belt and its Namaqua basement in southwestern Africa
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