Permian bivalves of the Taciba Formation, Itarare group, Parana basin, and their biostratigraphic significance

A small and poorly diversified bivalve fauna from Taciba Formation, Itarare Group, Parana Basin (State of Santa Catarina, Mafra Municipality), is described in this paper for the first time, based on new findings. The fauna is recorded in a 30 cm thick interval of fine sandstone locally at the top of Taciba Formation, in the Butia quarry. The studied fossil-bearing sand-stone bed is a marine intercalation recording a brief eustatic rise in sea-level, probably following glacier retreat and climate amelioration at the end of a broad glacial scenario. The fauna is mainly dominated by productid brachiopods, which are not described here, and rare mollusk shells (bivalves and gastropods). Two bivalve species were identified: Myonia argentinensis (Harrington, 1955), and Aviculopecten multiscalptus (Thomas, 1928). The presence of Myonia argentinensis is note-worthy since this species is also present in the Baitaca assemblage found in marine siltstones (Baitaca assemblage) of the Rio do Sul Formation, cropping out at the Teixeira Soares region, Parana State. This species is also recorded in the bivalve fauna from the Bonete Formation, Pillahinco Group, Sauce Grande Basin, Buenos Aires Province, in Argentina. Hence, the marine bivalves of the Taciba Formation are associated with the transgressive event that characterizes the Eurydesma fauna, indicating a Late Asselian-Sakmarian age for the bivalve fauna. Presence of the Myonia argentinensis megadesmid species reinforces the Gondwanic nature of the studied fauna.

Paleodistributions and Comparative Molecular Phylogeography of Leafcutter Ants (Atta spp.) Provide New Insight into the Origins of Amazonian Diversity

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Historical biogeography and conservation of the golden-striped salamander (Chioglossa lusitanica) in northwestern Iberia: integrating ecological, phenotypic and phylogeographic data

The golden-striped salamander (Chioglossa lusitanica) is an endemic species inhabiting stream-side habitats in mountainous areas in the northwestern Iberian Peninsula. This salamandrid is listed in the IUCN Red Data Book as a threatened species. The combination of bioclimatic modeling of the species distribution and multivariate analysis of genetic and phenotypic data strengthens previous hypotheses concerning the historical biogeography of C. lusitanica: the Pleistocene subdivision of the species' range and a process of postglacial recolonization. Discrepancies between bioclimatic modeling predictions and the present-day distribution suggest that the species may still be expanding its range northwards. We propose the identification of two distinct units for the conservation of the species and suggest that this information should be taken into account in defining key areas for conservation in the Iberian Peninsula.

Geographical variation in genetic structure of an Atlantic Coastal Forest frog reveals regional differences in habitat stability

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phylogeography of endemic toads and post-Pliocene persistence of the Brazilian Atlantic Forest

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Deglaciation sequences in the Permo-Carboniferous Itarare Group, Parana Basin, southern Brazil

The Late Carboniferous-Early Permian Itarare Group is a thick glacial unit of the Parana Basin. Five unconformity-bounded sequences have been defined in the eastern outcrop belt and recognized in well logs along 400 km across the central portion of the basin. Deglaciation sequences are present in the whole succession and represent the bulk of the stratigraphic record. The fining-upward vertical facies succession is characteristic of a retrogradational stacking pattern and corresponds to the stratigraphic record of major ice-retreat phases. Laterally discontinuous subglacial tillites and boulder beds occur at the base of the sequences. When these subglacial facies are absent, deglaciation sequences lie directly on the basal disconformities. Commonly present in the lowermost portions of the deglaciation sequences, polymictic conglomerates and cross-bedded sandstones are generated in subaqueous proximal outwash fans in front of retreating glaciers. The overlying assemblage of diamictites, parallel-bedded and rippled sandstones, and Bouma-like facies sequences are interpreted as deposits of distal outwash fan lobes. The tops of the deglaciation sequences are positioned in clay-rich marine horizons that show little (fine-laminated facies with dropstones) or no evidence of glacial influence on the deposition and likely represent periods of maximum ice retreat. (c) 2006 Elsevier Ltd. All rights reserved.

Quaternary of the Pantanal, west-central Brazil

The Pantanal is a tectonic depression located at the left margin of the Upper Paraguay River. The Paraguay is the trunk river of an alluvial depositional tract composed by several large marginal alluvial fans, the Taquari fan being the largest one. The present landscape is a complex tropical wetland characterized by month-long floods every year, with geomorphic features derived from the present conditions and others inherited from successive Pleistocene and Holocene climates. Some areas containing ponds are landscape relicts generated by eolian deflation during the Last Glacial Maximum. Many ponds, closed depressions isolated from the superficial waters by vegetated crescent ridges of fine sands, were interpreted as salt pans bordered by lunette sand dunes. Initiation of the modern wetland has occurred during the Pleistocene/Holocene transition, with the change to a more humid climate and the individualization of lacustrine systems. Active tectonics has been playing an important role in the development of the Pantanal landscape. Nowadays, the Paraguay River meanders in a large flood plain with extensive swamp surfaces, being structurally constrained by faults in the west border of the basin. Sedimentation within the Pantanal wetland is also affected by tectonic activity, especially along faults associated with the Transbrasiliano Lineament. (C) 2003 Elsevier B.V. Ltd and INQUA. All rights reserved.

Glacially striated, soft sediment surfaces on late Paleozoic tillite at São Luiz do Purunã, PR

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Analysis of tectonic-controlled fluvial morphology and sedimentary processes of the western Amazon Basin: an approach using satellite images and digital elevation model

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Simulação geoestatística na caracterização espacial de óxidos de ferro em diferentes pedoformas

Os minerais da fração argila, goethita e hematita, são óxidos de ferro (Fe) indicadores pedoambientais com grande influência nos atributos físicos e químicos do solo. O conhecimento dos padrões espaciais desses óxidos auxilia a compreensão das interrelações de causa e efeito com os atributos do solo. Nesse sentido, a qualidade das estimativas espaciais produzidas pode alterar os resultados obtidos e, por consequência, as interpretações dos padrões espaciais obtidos. O presente estudo teve o objetivo de avaliar o desempenho dos métodos geoestatísticos de estimativas (KO) e simulações sequenciais gaussianas (SSG) na caracterização espacial de teores de óxidos de Fe, goethita (Gt) e hematita (Hm), em uma pedoforma côncava e outra convexa. Foram coletadas 121 amostras de solos em cada pedoforma de um Argissolo em pontos com espaçamentos regulares de 10 m. Os teores de óxidos de Fe foram obtidos por meio de difração de raios-X. Os dados foram submetidos a análises geoestatísticas por meio da modelagem do variograma e posterior interpolação por KO e SSG. A KO não refletiu a verdadeira variabilidade dos óxidos de Fe, hematita e goethita, demonstrando ser inapropriada para a caracterização espacial dos teores dos óxidos de Fe. Assim, o uso da SSG é preferível à krigagem quando a manutenção dos altos e baixos valores nas estimativas espaciais é necessária. O desempenho dos métodos geoestatísticos foi influenciado pelas pedoformas. Os mapas E-type devem ser recomendados em vez de mapas de KO para os óxidos de Fe, por serem ricos em detalhes e práticos na definição de zonas homogêneas para o manejo localizado em frente de KO, sobretudo em pedoforma côncava.

Otimização amostral de atributos de latossolos considerando aspectos solo-relevo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Well productivity controlling factors in crystalline terrains of southeastern Brazil

Over the last decades, increasing water demands have fostered research to obtain high well yields in crystalline terrains where, besides the intrinsic properties of rocks, the groundwater flow depends on several factors. The depth of the wells, the lithotypes, the presence and thickness of sedimentary coverings and weathered layers, the landforms, the geological structures, and the effects of tectonic stresses are among the most investigated factors considered as determinant of well productivity. The influence of these factors on productivity of wells that exploit the Crystalline Aquifer System in the Jundiai-River Catchment, southeastern Brazil, is investigated in this work. The largest region of the studied area is located on the Precambrian Basement, partially covered by sedimentary deposits. The results show that the sedimentary deposits and the weathered layer are important for high well yield, but it also depends on the existence of a net of open fractures, in order to maintain high productivity. The sites that have more possibility of occurrence of such structures are the regional shear and fault zones and other minor structures with NW-SE and E-W directions, which characterize areas subjected to transtensional stress related to the neotectonics.

Obtencao e interpretacao de dados de Reflexao Sismica Superficial (Rasa) - exemplos e aplicacoes

Successful application of shallow seismic reflection method is related directly to the ability of the ground to transmit high-frequency seismic energy from a seismic source. The dominant frequencies of reflection data are in the range of 50 to 100 Hz and depend on the surface materials and water table. A spread of geophones send the siemsic signal to be recorded on a 12, 24 or 48 channel portable seismograph, using a single high-frequency geophone per channel. Although it is possible to find seismographs with display and processing unities, it is also possible to transfer digitalized data to a personal computer to be processed and interpreted by using specific programs. Some results of two recent field studies to specify the underground structure in the tidal flats area of Baie St. Paul (Quebec-Canada) and in glacial terrains, in the Waterloo (Ontario-Canada) region. -from English summary