The Trairão area as a boundary between geochronological provinces of the Amazonian craton based on U-Pb and Sm-Nd data from two flare-ups

The Trairão area, in the central Amazonian Craton, records extensive Orosirian volcano-plutonic events dominated by acid and subordinate intermediate rocks. U-Pb LA-ICP-MS zircon geochronology reveals two magmatic flare-ups separated by a ca. 100 M.y. lull: (1) a plutonic-dominated phase at ca. 1980 Ma, and (2) a volcanic phase at ca. 1880 Ma. Previous geochemical data distinguish calc-alkaline and alkaline suites, positioning Trairão as a key area for reevaluating geotectonic boundaries. Sm-Nd whole-rock analyses ( ε Nd (t) = −1.39 to −7.11; Nd-T DM = 2.31–2.64 Ga) indicate magma derivation from mixed Archean and juvenile Paleoproterozoic sources. These results define a NW-SE boundary separating the Tapajós (TJD; Nd-T DM <2.5 Ga) and Iriri-Xingu (IXD; Nd-T DM >2.5 Ga) domains, correlating with the Ventuari-Tapajós and Central Amazonia provinces, respectively. We propose that the Orosirian TJD magmatic arc was accreted onto the IXD continental domain, followed by extensional alkaline magmatism (Silicic Large Igneous Province - SLIP).