From rifting to collision: deep closure of a Wilson cycle during the Archean–Paleoproterozoic transition at the Carajás-Bacajá boundary, Amazonian Craton

Felipe Mattos Tavares , Cintia Maria Gaia Silva, Joseneusa Brilhante Rodrigues, Rudolph Allard Johannes Trouw, Julio Cezar Mendes

The Carajás-Bacajá boundary preserves complementary archives of continental rifting, passive-margin development, subduction, collision and post-collisional exhumation across the Archean-Paleoproterozoic transition. We present whole-rock lithogeochemistry, Sm-Nd isotopes, U-Pb zircon geochronology and thermobarometry from the Vila Santa Fé-Rio Preto association, a mafic-felsic granulitic assemblage tectonically above the Buritirama succession. Rio Preto-type mafic granulites define a comparatively juvenile pole, whereas arc-modified felsic orthogneisses have negative εNd at ca. 2.10 Ga, TDM ages of ca. 2.44-2.46 Ga and Archean inherited zircon. U-Pb zircon records lower-crustal melt growth at 2097 ± 19 and 2093 ± 25 Ma, followed by granulite-facies recrystallization, migmatization and charnockitic to enderbitic melt generation between 2073 ± 3 and 2067 ± 7 Ma. Thermobarometry constrains a 9-10 kbar, 760-800 °C granulitic root, followed by hydrated decompression at 7-8 kbar and 690-710 °C; Carajás-side amphibolite records ca. 700-720 °C. Structural, geophysical and 40Ar/39Ar constraints define southwest-verging stacking of Bacajá lower crust over Buritirama and northern Carajás between ca. 2.10 and 2.05 Ga. Published data extend the reconstruction backward. A 2549 ± 5.9 Ma A2-type granite and proximal ca. 2.55 Ga detritus date rift initiation; upward provenance broadening, seawater-like carbonate chemistry, positive pre-ore δ13C and later manganese accumulation record margin maturation and sediment starvation. Apparent Paleoproterozoic detrital ages in Buritirama are reproducible by low-discordance Pb loss from Archean zircon. The same correction applies to the Novolândia granulite belt, whose sedimentary protoliths carry a 3.32–3.18 Ga Paleoarchean provenance peak, 2.75 and 2.55 Ga magmatic populations and a rift-type granite crystallized at 2567 ± 22 Ma with 2744 ± 21 Ma inheritance, identifying the far side of the closed ocean as a detached fragment of the Carajás margin. Bacajá arc magmatism at ca. 2.21-2.13 Ga and coeval fluid-assisted re-equilibration in Carajás define upper- and lower-plate responses consistent with slab-pull extension. Decompression, rapid cooling and the unconformable Águas Claras basin, whose basal marine interval is exposed at Azul and Serra Pelada, record collapse and renewed marine transgression. The direct result is the Rhyacian collisional stack; the full Wilson cycle is the integrated model that explains the ordered regional evidence.