The U–Pb and Lu–Hf zircon record of the Neoproterozoic tectonomagmatic evolution of the Ventania System basement, central-eastern Argentina: The southernmost exposure of the Dom Feliciano Belt?

BALLIVIÁN JUSTINIANO, CARLOS A; ORIOLO, SEBASTIÁN; ARNOL, JONATAN; RENDA, EMILIANO M.; BASEI, MIGUEL A.S.

PRECAMBRIAN RESEARCH

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2023 vol. 399 p. 1 - 20

0301-9268

In the Ventania System of central-eastern Argentina, Neoproterozoic igneousrocks of the Sauce Chico Complex (SCC) crop out. They consist of low-grademylonitized granites and rhyolitic rocks. Metasedimentary rocks are representedby metapelite and metacarbonate xenoliths hosted in Neoproterozoic granites. Thiswork presents lithogeochemical, and coupled LA-MC-ICP-MS U–Pb and Lu–Hf zircondata of Neoproterozoic rocks of the SCC in order to reinforce the alreadyproposed link between these rocks and the Brasiliano/Pan-African Dom FelicianoBelt of southern Brazil and eastern Uruguay. Novel U–Pb results yieldedcrystallization ages of 623 ± 3 Ma and 608 ± 4 Ma in granite samples, and 545 ±3 Ma in a tuff sample. Considering these new U–Pb ages and those published inprevious works, Neoproterozoic rocks of the SCC can be grouped in Tonian (ca.784–777 Ma) and Ediacaran (ca. 623–607 Ma) granites, and Ediacaran (ca.577–544 Ma) volcanic and pyroclastic rocks. Xenocrystic/inherited ages spanfrom the Ediacaran (ca. 555 Ma) to the late Neoarchean (ca. 2535Ma). Ninety-four spots on zircon grains gave the following U–Pb and Lu–Hf results:ca. 2040–1700 Ma (n = 6, εHf(t) = -14.6/+6.3, TDM= 3.5–2.1 Ga); ca. 1500–850 Ma (n = 9, εHf(t) = -26.3/+4.5, TDM= 3.3–1.9 Ga); ca. 830–700 Ma (n = 26, εHf(t) = -40.5/+10.7,TDM = 4.1–0.9 Ga); and ca. 650–530 Ma (n = 53, εHf(t)= -38.8/+2.9, TDM = 3.9–1.3 Ga). When the Neoproterozoic rocks ofthe SCC are compared with those of the Punta del Este Terrane of the DomFeliciano Belt, lithological, geochemical, geochronological, and isotopicsimilarities are evident. Both regions have Tonian orthoderived rocks (ca.800–760 Ma) intruded by Ediacaran granites (ca. 630–570 Ma), and lateEdiacaran plutonic and volcano-sedimentary rocks (< ca. 580 Ma). Tonianrocks of the Punta Mogotes Formation (Mar del Plata city area, southeasternmosttip of the Tandilia System) might represent the connection between the Puntadel Este Terrane and the Ventania System basement. Additionally, the presenceof Brasiliano/Pan-African rocks along the southern border of the Río de laPlata Craton effectively eliminates the possibility of the craton extending furthersouth/southwest of the system.