Geochronology (U-Pb) and isotope geochemistry (Sr/Sr and Pb/Pb) applied to the Várzea do Capivarita Metamorphic Suite, Dom Feliciano Belt, Southern Brazil: Insights and paleogeographical implications to West Gondwana evolution.

Abstract

Geochronological and isotope geochemistry analysis on the marbles and pelitic gneisses outcropping in the Várzea do Capivarita Metamorphic Suite (VCMS) in the Dom Feliciano Belt (DFB), Southern Brazil, confirms its origin during the agglutination of Congo-Kalahari-La Plata cratons into the Gondwana Supercontinent, in the Tonian-Cryogenian periods. Detrital zircon ages displayed provenance from local sources (2.2 - 2.0 Ga), from development of rifting processes (1.7 Ga) and agglutination of terranes in the Neoproterozoic (0.7 Ga), and constraint the pelitic sediment deposition within minimum detrital age of 728 ± 11 Ma and metamorphic age of 618 ± 7.3 Ma. Whole-rock ⁸⁷Sr/⁸⁶Sr ratio of 0.70609 indicates a deposition age of 717 - 750 Ma to the marble sequences. ²⁰⁶Pb/²⁰⁴Pb and ²⁰⁷Pb/²⁰⁴Pb data are similar to those obtained of stromatolitic dolomites in Gariep Belt (Kalahari) but some ratios are similar to signatures of Neoproterozoic (ca. 800 Ma) volcanic arcs (Cerro Bori Continental Arc) in the Rio de La Plata craton. VCMS metapelites can be understood as plataformal sequences deposited during agglutination of terranes between Kalahari and Rio de La Plata cratons in the Neoproterozoic.