Magmatism in the Asunción-Sapucai-Villarrica Graben (Eastern Paraguay) Revisited: Petrological, Geophysical, Geochemical, and Geodynamic Inferences

Figure 2

Geological sketch map of Eastern Paraguay (modified after [10, 13, 20–24]). ASV: Asunción-Sapucai-Villarrica graben. (1): Neogene and Paleogene sedimentary cover (e.g., Gran Chaco); (2): Paleogene sodic alkaline rocks, Asunción Province; (3): Late-Early Cretaceous sodic alkaline rocks (Misiones Province, San Juan Bautista, SJB); (4): Early Cretaceous potassic alkaline rocks (posttholeiites; ASU: Asunción-Sapucai-Villarica graben, Central Province); (5): Early Cretaceous tholeiites of the Paraná Basin (Serra Geral Formation in Brazil and Alto Paraná Formation in Paraguay; cf. [4]); (6): Early Cretaceous potassic alkaline rocks (pretholeiites, Apa and Amambay Provinces); (7): Jurassic-Cretaceous sedimentary rocks (Misiones Formation); (8): Permo-Triassic alkaline rocks (Alto Paraguay Province); (9): Permian sedimentary rocks (Independencia Group); (10): Permo-Carboniferous sedimentary rocks (Coronel Oviedo Group); (11): Ordovician-Silurian sedimentary rocks (Caacupé and Itacurubí Groups); (12): Cambro-Ordovician platform carbonates (Itacupumí Group); (13): Archean to Early Paleozoic crystalline basement: high- to low-grade metasedimentary rocks, metarhyolites, and granitic intrusions; (14): major tectonic lineaments and faults. The radiometric values, for example, 133 Ma, are referred to ⁴⁰Ar/³⁹Ar plateau ages for the main magmatic types [25–27] and to Rb/Sr ages for the Precambrian rhyolitic rocks of Fuerte Olimpo and Fuerte San Carlos [28].