| dc.description.abstract | The stragraphic posioning of rocks grouped as Cambotas Formaon (Quadrilátero Ferrífero, southeast of São Francisco Craton) has been the subject of discussion since its characterizaon in the 1960s. Our study provides structural and stragraphic data of the Cambotas Formaon, obtained in its type-secon along with the Tamanduá and Cambotas mountain ranges, with the aim of defining the stragraphic-temporal relaonships that characterize the Cambotas Formaon and its surroundings. Also presents isotopic data (U-Pb
in LA-ICP-MS) intended to shed light on the age of the unit, The large shear zone systems already described in the literature were observed, as well as the textural and sedimentological characteriscs. The Cambotas Formaon corresponds to a unit that groups together orthoquartzites and arcosian quartzites, whose basic stragraphic relaonship is controlled by tectonic contacts, through the Fundão-Cambotas Shear Zone System, and by the Córrego do Garimpo Fault. For provenance via U-Pb isotopic analysis in LA-ICPMS of detrital zircon grains, a sample collected from the Cambotas Formaon in its type-secon, in the homonymous mountain range,
corresponding to fine-grained orthoquartzite, in which 210-zircon grains collected and analyzed. The results indicate maximum sedimentaon age during the Statherian, around 1755 ± 71 Ma, the peaks of ages between 1923 and 3010 Ma indicates a significant contribuon of Paleoproterozoic to Neoarquean sources. In the light of current stragraphic knowledge, the peak of concordant analyzes with Statherian age (~ 1.7 Ga) discards the correlaon between the Cambotas Formaon and the Minas or Rio das Velhas supergroups. With this, we propose that the Cambotas Formaon configure the southern terminaon of the Espinhaço Supergroup, corresponding to a restricted basin, with a mulplicity of source areas. This variety relates to the structural and stragraphic complexity to which the northeastern region of the current Quadrilátero Ferrífero was subjected during its genesis. The sample provides an age similar to other works in the same area, validang the stragraphic proposals presented. | |
