Mário Sérgio de Melo

Fácies sedimentares da Formação Rio Claro, neocenozóico da depressão periférica paulista

The Rio Claro Formation and associated deposits comprise continental Neocenozoic sediments of the Depressao Periferica (inner lowlands) of southeastem Brazil. These sediments are discontinuous and thin, and their interpretation and classification required the use of geomorphic concepts as well as the usual lithostratigraphic ones. Five planation surfaces of regional extent have been recognized; the lowest and youngest three occur within the limits of the Depressao Periferica, whereas the oldest two occur at higher levels in the neighbouring terrams. Coarse deposits and ferricretes associated with these planation surfaces suggest that they were formed during pediplanation cycles under dry climatic conditions. The Rio Claro Formation is more continuous in its type-area (near the city ofRio Claro), and is discontinuous near the eastem border of the Depressao Periferica. It lies upon the two highest planation surfaces which leveled the hills ofthe area, and has about the same age as these surfaces. It contains deposits of meandering fluvial system formed under humid climates, comprising four principallithofacies: sandy and gravelly muds due to gravity processes; gravels and sands of channellag and channel bar deposits; sands of crevasse splay deposits; and flood pIam muds. In the type-area of the Rio Claro Formation accumulation was controlled by the Neogene reactivation of faults with vertical displacements in the Pitanga structural high, which were active mainly in Mesozoic times. On the eastem border of the Depressao Periferica the Neocenozoic sediments show clear association with lithological barriers (diabase sills and dykes)

Palinologia de sedimentos da Bacia de São Paulo, Terciário do Estado de São Paulo, Brasil

The Tertiary sediments of the Sao Paulo Basin, which include the Sao Paulo and Itaquaquecetuba Formations, have been recently interpreted as a Paleocene sedimentary ensemble comprising: a basal alluvial fan to braided-stream system; a partially contemporaneous lacustrine system; a meandering fluvial system at the top of the sequence. The origin of the Itaquaquecetuba Formation (braided-channel system) is controversial, and it has been considered by different authors as having been associated with the basal deposits of the basin and as due to tectonic reactivation and sediment reworking during the Neogene or Quaternary. This study comprises the palynological analysis of sediments from the alluvial fan, laustrine and braided-stream systems (this latter attributed to the Itaquaquecetuba Formation); the respective palynofloras are homogeneous and include several taxa of stratigraphic and paleoclimatic value, suggesting very close ages and climates. The dorninance of Oligocene taxa together with only a few others considered as Eocene or older suggest two hypothesis: 1) possible reworking of Eocene sediments in the Oligocene; 2) the taxa previously considered as Eocene in age may have, in fact, lived until Oligocene, and so should have their distribution interval suitably corrected. The relative abundance of taxa indicating colder climates (conifers) and the scarcity of others more typical of hot and wet climate suggests that sedimentation took place under cold conditions. However, it was not possible to establish precisely the influence of altitudinal floristic differentiations in the preserved palynological assemblage

Faciologia e contexto deposicional da Formação Guabirotuba, Bacia de Curitiba (PR)

A Bacia de Curitiba situa-se na porcao meridional do Sis- tema de Riftes Cenozoicos do Sudeste do Brasil (SRCSB). Possui cerca de 3.000 km2 de sedimentos cenozoicos com espessura preservada de ate 80 m, denominados de Formacao Guabirotuba. As pesquisas realizadas se ocuparam da caracterizacao sedimentologica e evolucao da compar- timentacao tectonica da bacia. Porem, a distribuicao das associacoes de facies sedimentares e seu contexto deposicional nao foram analisados de modo sistematico e, ainda hoje, prevalecem interpretacoes baseadas nos levantamentos das decadas de 1960 e 1980 ou em correlacoes com ou- tras bacias do SRCSB. E nesta circunstância que este estudo investigou o contexto deposicional dos sedimentos da Bacia de Curitiba por meio da analise dos elementos arquitetonicos e sua distribuicao em exposicoes de superficie. A arquitetura deposicional e os rumos medios de paleo- correntes permitem interpretar que as associacoes A, B, C e D sao de- positos de transicao entre as zonas proximais, intermediarias, e distais de sistemas distributarios fluviais. Por outro lado, as associacoes E e F exibem caracteristicas faciologicas e sedimentologicas distintas em rela- cao as demais associacoes de facies. Sua distribuicao restrita sugere que sistemas fluviais contemporâneos aos demais, mas com sutis diferencas se formaram nos setores oeste e nordeste da bacia. Estes setores coincidem com aqueles onde foram descritas as formacoes Tinguis e Piraquara, in- terpretadas como unidades distintas da Formacao Guabirotuba. A abun- dante quantidade relativa de lama e a ausencia de facies eolicas e/ou de feicoes sedimentares de exposicao e ressecacao, sugerem que tais sistemas formaram-se em condicoes de clima razoavelmente umido.

A GEODIVERSIDADE DA REGIÃO DE PIRAÍ DA SERRA. DOI: 10.5212/Publ.Exatas.v.17i1.0005

A regiao de Pirai da Serra, um poligono que compreende segmentos dos municipios de Castro, Tibagi e Pirai do Sul, no reverso imediato da Escarpa Devoniana, contempla um rico patrimonio natural ainda preservado. A geodiversidade de Pirai da Serra, ou seja, seu lado abiotico, e representada por litologias da Bacia do Parana, de seu Embasamento e do Magmatismo Serra Geral, com predominio dos arenitos da Formacao Furnas. Dentre as formas de relevo, destacam-se aquelas controladas pelo Arco de Ponta Grossa, como canyons , escarpamentos e cachoeiras, alem das feicoes ruiniformes tipicas da Formacao Furnas esculpidas pela acao das aguas pluviais. Como classes de solos, predominam os NEOSSOLOS LITOLICOS, que juntamente com outros tipos constituem o resultado da pedogenese. Este mecanismo geologico, ao lado do ciclo hidrologico e demais acoes geomorficas atestam o predominio atual da operacao de processos exogenos na regiao de Pirai da Serra, tais como intemperismo e erosao.

A geodiversidade da Região de Piraí da Serra (Pr)

The region of “Piraí da Serra”, on the boundaries of the municipalities of Castro, Tibagi and Piraí do Sul, is located at the dip slope of the Devonian Scarp and comprises a rich natural preserved heritage. For this reason, researchers from the Ponta Grossa State University carried out an interdisciplinary project from 2007 to 2009. This paper includes the results of the physical/natural study group, whose aim was to characterize the geodiversity of this region. To this end, periodic fieldwork was conducted, together with photointerpretation and analysis DOI: 10.5212/Publ.Exatas.v.17i1.0005 * Universidade Federal de Santa Catarina (UFSC) E-mail: <fernandamochiutti@yahoo.com.br> ** Universidade Estadual de Ponta Grossa (UEPG) E-mail: <rafaelkoene@hotmail.com> *** Departamento de Geociências da Universidade Estadual de Ponta Grossa (DEGEO-UEPG) E-mail: <gburigo@ig.com.br> **** Departamento de Geociências da Universidade Estadual de Ponta Grossa (DEGEO-UEPG) E-mail: <msmelo@uepg.br> 52 Nair Fernanda Mochiutti; Rafael Köene; Gilson Burigo Guimarães; Mário Sérgio de Melo Publ. UEPG Exact Earth Sci., Agr. Sci. Eng., Ponta Grossa, 17 (1): 51-65, jan/jun. 2011 Disponível em <http://www.revistas2.uepg.br/index.php/exatas> of topographical, geological maps and satellite images, as well as an extensive literature review. In summary, the geodiversity of Piraí Sierra is represented by lithologies of the Paraná Basin, mainly Siluro-Devonian sandstones of the Furnas Formation, country rocks of the Castro Group, and also intrusive rocks related to the Cretaceous Serra Geral Magmatism. The Ponta Grossa Arch controlled the expression and development of the main landforms, such as canyons, escarpments and waterfalls, while the meteoric waters sculptured the typical ruiniform features of the Furnas Formation sandstones. The classes of soils that predominate are the Entisols, which along with other types of soil are the result of pedogenesis. This geological mechanism, together with the water cycle and other geomorphic actions, confirm the predominance of exogenous processes in the Piraí da Serra region, such as weathering and erosion.

Sedimentologia dos depósitos cenozóicos continentais do Baixo Vale do Rio Ribeira do Iguape, SP

Recent studies on continental deposits that occur at the lower Ribeira do Iguape river valley (southern State of Sao Paulo, Brasil), led to the recognition of five different stratigraphic units, namely: the Sete Barras Formation, the Pariquera-Acu Formation, two levels of fluvial terraces, and colluvial-alluvial deposits. All these sediments were formerly attributed to the Pariquera-Acu Formation (with stages I,IIand III), considered to be Pleistocene. This paper presents the stratigraphic and sedimentological data which support the re-definition of the Pariquera-Acu Formation. Field work and grainsize analysis allowed to determine the main sedimentary processes for each unit. Maturity of heavy-minerals and nature of clays support the interpretation of paleoclimates. Both processes and paleoclimates pointed toward probable depositional systems and Cenozoic evolution of the area