Evolution of the Carboniferous-Early Cretaceous units of Paraná Basin from provenance studies based on U-Pb, Hf and O isotopes from detrital zircons

Abstract

U-Pb, Lu-Hf and O isotope data were obtained on detrital zircons from late Paleozoic-early Mesozoic units from White Column, Paraná Basin, southeastern Brazil, in order to characterize the provenance of the sediments, as well as to contribute to the understanding of the evolution of the basin. The studied section includes rocks from 11 stratigraphical units (from base to top), including the Rio do Sul Formation, Rio Bonito Formation (Triunfo, Paraguaçu and Siderópolis members), Palermo, Irati, Serra Alta and Teresina formations, Rio do Rasto Formation (Serrinha and Morro Pelado members) and Botucatu Formation.U-Pb ages of zircons in these units range from 242Ma to 3.4Ga. All units show four main detrital age-groups, Neoarchean, mid-Paleoproterozoic, Grenvillian and Brasiliano-Pan African reflecting the importance of the Precambrian basement bordering the east side of the section such as Dom Feliciano, Kaoko and Namaqua-Natal Belts as source areas. However, the isotopic signatures show that a portion of the mid-Paleoproterozoic zircons (1.9–2.0Ga) are probably from rocks of the presently covered basement, which was exposed until the deposition of the Rio Bonito Formation. The isotopes also show some Grenvillian aged zircons from Argentinian rocks, which implies a long transport distance.The Siderópolis Member is the unit that shows an important change on the sources of the sediments, since it contains a Permian age peak that was not present on the lower units and that persist on the upper units. The isotopic signatures of these Permian grains link them to the Choiyoi igneous province and North Patagonia Massif, sources from Argentina, reaching the basin by long distance travel on subaquatic environmental and not only from the air (ash falls) as is in common acceptance. Other younger age peaks (Ordovician to Carboniferous) found from Palermo Formation to up section are also linked to Argentinian sources, showing the importance of the long travel distance during the filling of the basin.