Understanding the evolution of the northern Dom Feliciano Belt foreland basin: A review of structural and geochronological evidence

The Itajaí Basin evolution provide evidence of late tectonic processes within the context of the Dom Feliciano Belt northern sector. The foreland basin was formed during the late thrusting and folding of the Schist Belt/Brusque Group, which overthrusts the southeastern boundary of the basin in the Itajaí-Perimbó Shear Zone (IPSZ). The basin underwent two main deformation patterns: the first resulted in locally asymmetrical NE-SW trending folds and thrust faults, while the second encompassed large-scale open folds that affected the structures formed during the first deformation event, such as cleavages and fold axes. Evidence of interlayer deformation can be observed within the sedimentary layers, both during deposition and as a result of flexural slip associated with the folding. The relationship between felsic magmatism and the basin stratigraphy continues to be elucidated through new geochronological and geochemical data obtained from sedimentary, tuff, and volcanic/subvolcanic rocks present in the Itajaí Basin. A range of geochronological data is available in the basin context, mainly from zircon U-Pb analysis on tuffs from at least three locations, volcanic clasts in the basal conglomerates, detrital zircons in sedimentary units, the felsic magmatism from domes and intrusive rocks, sills and rhyolites within the bedding of the sedimentary units, syenogranites in the western portion of the basin, Rb-Sr ages in total rock and fine fractions of siltstones, muscovite Ar-Ar ages from Brusque Group schists near the IPSZ, ages from late deposits in the context of the IPSZ, and detrital zircon ages in metasedimentary units interleaved in the Brusque Group. A comprehensive evaluation and review of these data was conducted in order to contribute to the understanding of the Itajaí Basin structural evolution timing. The main chronological stages in the evolution begin with the early sedimentation stage, dated at 596 ± 10 Ma (1). Volcanic activity and intrusions occur in the upper portions of the basin at 560 Ma, while tuffs situated in the intermediate regions of the basin present ages at 563 ± 0.3 Ma (2). The sedimentary layers reached their thermal peak at 535 ± 11 Ma (1,3), followed by the emplacement of the Subida syenogranite at 520 Ma (1). (1) Basei et al. (2011). International Journal of Earth Sciences 100: 543-569. (2) Becker-Kerber et al. (2020). Gondwana Research 84: 211-228. (3) Macedo et al. (1984). Revista Brasileira de Geociências 14: 1.