SEDIMENTAÇÃO QUATERNÁRIA NO ESPAÇO URBANO DE PONTA GROSSA, PR

M.S de Melo, Carla V. Medeiros, P.C.F. Giannini, M.J. Garcia, L.C.R. Pessenda - Quaternary Sedimentation in Ponta Grossa, Parana State, Southern Brazil.The city of Ponta Grossa is placed in the Southeastern Parana state, Southern Brazil, over sedimentary rocks of the Furnas and Ponta Grossa formations (Devonian) and of the Itarare Group (Carboniferous) of the Parana Basin. These rocks emplace diabase sills and dykes related to the Serra Geral Magmatism (Cretaceous). Quaternary sediments are common (as colluvial-eluvial ramps, fans, terraces and alluvial plains), indicating phases of thalweg silting. These deposits assume importance because they constitute the raw material for many local brickyards and because they are subjected to active erosive processes. The Quaternary sediments are thin and discontinuous, showing alternation of alluvial and gravitational material, with accentuated textural variation. Unstable minerals (clinochlore and siderite) present in some of the deposits suggest genesis during phases of bio-rhesistas y, with denudation of the rocky substratum, under climate conditions little propitious to weathering. Preliminary palynological analysis allow to identify Devonian material reworking as well as varied Quaternary taxa (mushrooms, algaes, bryophyites, pteridophytes, gimnospermous, angiospermous), with dominance of gramineous, suggesting dryer paleoclimatic conditions during accumulation, with a short hotter and humid season. 14