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Sediment provenance of the Curitiba basin by study of heavy minerals. Curitiba Basin is located in the South-central portion of the first plateau of Parana. It includes the city of the same name and some towns of the metropolitan region. It is a neogean basin elongated towards ENE direction, which belongs to the Cenozoic Rift System in Southeast Brazil. Its maintained sedimentary fill extends over 3,000 km2 and includes sludge, arkosic sands, and gravels of Guabirotuba Formation. Among the basins that are part of the Cenozoic Rift System of Southeast Brazil, Curitiba Basin is the least studied in details. Until the present moment, researches on this accessory assembly were not disclosed. We have analyzed transparent, nonmicaceous and nonmagnetic heavy minerals, with fraction of particle size from 3 - 4 φ (0.125 - 0.062 mm), which were separated using bromoform (d = 2.89 g/cm³) and handheld magnet. The determination was done with permanent assemblies of grains and Canada balsam (n = 1.53), analyzed in a petrographic microscope. In the mineralogical assembly, zircon grains, epidote, tourmaline, kyanite, rutile, and traces of sillimanite and garnet were predominantly found. Zircon occurs as euhedral to sub-euhedral grains, colorless to subordinate pink and metamict. The study of heavy minerals in Curitiba Basin suggests that towards the center of the basin, zircon quantities tend to decrease while amounts of epidote increase. Two mineralogical associations were characterized: the first, called High Zircon, has zircon quantities between 51 to 97%; the second one was called High Epidote and has relative epidote amounts between 31 to 53%. Such differences in zircon and epidote values allow to infer the possibility of having more than one source area for these sediments. The main paleocurrents trends indicated the granites of Graciosa Province and metamorphic rocks of the Atuba Complex as potential source rocks. Moreover, one cannot rule out the possibility of hydraulic segregation. Since zircon is denser, it tends not to move so much the basin transport as the epidote, which presents the lowest density. Therefore, it was concluded that the relative proportion between these two minerals would be a good tracer of the dynamics of sediment transportation in the basin.

Proveniência de sedimentos da Bacia de Curitiba por estudos de minerais pesados