AMS and grain shape fabric of the Late Palaeozoic diamictites of the Southeastern Paran Basin, Brazil

Diamictites interbedded with marine shales and turbidites onlap the eastern border of the Parana Basin (Southern Brazil). These poorly sorted sediments were deposited during the Permo-Carboniferous glaciation, and their matrix-supported clasts show no preferred orientation. These massive rocks have been studied using anisotropy of magnetic susceptibility (AMS) and grain shape fabric. Hysteresis loops and thermomagnetic measurements show that AMS depends mostly on the paramagnetic clays, but fine ferromagnetic particles also contribute to the anisotropy. The coarse silt to sand grain preferred orientation study supports the use of AMS in describing the diamictite fabric, at least regarding the orientation of the foliation. AMS and grain shape data reveal subhorizontal to weakly inclined magnetic and grain shape foliation parallel to the regional bedding. The magnetic lineations are normally scattered within the foliation plane in agreement with the oblate AMS ellipsoids found in these rocks. Both fabric patterns are consistent with deposition by subaqueous mudflows that were resedimented downslope, with elastic supply from continental sources. The off-vertical grain shape foliation poles suggest that the deposition of diamictites was controlled by the depocentre topography of the Rio do Sul sub-basin.

Seqüência Ordovício-Siluriana e Devoniana no Flanco Norte da Bacia do Paraná

Two stratigraphic sequences characterize the basal units of the Paraná basin. The Ordovician-Silurian sequence overlie directly the Neoproterozoic basement and consists of a 55m-thick unit of coarse-grained sandstones, diamictites, fossiliferous shales and fine-grained micaceous sandstones. The Alto Garças Formation constitutes the base of the sequence and is made of coarse-grained, massive and reddish sandstones associated with conglomeratic lenses. Diamictites with pebbles of diverse composition in siltic and arenaceous matrix were deposited during the Ordovician-Silurian glaciation. Whenever the basal sandstones are absent, the diamictites directly overlie the basement. The diamictites were previously included in the Vila Maria Formation. However our study revealed that they are part of the Iapó Formation. A transgressive event following the glaciation is marked by the deposition of the Vila Maria Formation, which is characterized by fossiliferous (mollusks, brachiopods, cryptospores and microplankton) and laminated shales and siltstones, grading upward to fine-grained micaceous sandstones with hummocky cross stratification. Layers containing trace fossils (Anthrophycus) occur at the transition between the siltstones and the sandstones. The Devonian sequence is represented by 80-170 meters thick sandstones of the Furnas Formation (lower unit) and a sucession of sandstones, siltstones and shales of the Ponta Grossa Formation (upper unit). Unlike other areas of the Paraná Basin, the Ponta Grossa Formation is characterized by coarsening-upward succession beginning with fine sandstones and grading upward to coarse and very-coarse sandstone beds. Cretaceous modifying tectonics affected the Paleozoic sequences, which are cut by a series of faults, in some cases showing displacements greater than 500 meters.

Aves colecionadas na localidade de Fazenda Caiuá (Paraná, Brasil) por Adolph Hempel, com discussão sobre a sua localizaç ão exata

The region known as the pioneer north of Paraná State can be considered one of the most severely modified in southern Brazil, due to the colonization that started at the end of 19th century. In this little known region, seldom visited by traveler naturalists of the past, the collector Adolph Hempel obtained an important series of bird specimens that constitute, in many cases, the only - and last - information concerning the avifauna of this region. For several reasons, Fazenda Cayoá has been associated with the State of São Paulo, although it was an important center for coffee in the early 20th. century and is near the left bank of Rio Paranapanema, thus in the State of Paraná.

Aplicação do Índice Relaçáo Declividade-Extensão - RDE Na Bacia do Rio do Peixe (SP) para Detecção de Deformações Neotectô nicas

This paper presents the identification of tectonic deformation through the application of the stream-gradient index (slope x length) method in the Rio do Peixe hydrographic basin, located in western State of Sã o Paulo. The main principle used is that river valleys are the best tools for this type of analysis because of their fast adjustment to even the most gentle crustal deformations. This type of analysis for structural studies is extremely useful in the western region of the State of São Paulo, where deep chemical weathering results in a thick regolith and scarce outcrops. The stream length index is the ratio of the altimetric amplitude of each drainage and the natural logarithm of its length. The value obtained is plotted on maps at the median point of each drainage, allowing the drawings of lines with the same values (isodefs). Three anomalies (A, B and C) were identified along the Rio do Peixe valley representing uplift sectors indicated by the formation and distribution of Upper Quaternary deposits in terraces and modern fluvial plains and alluvial fans. In correlation with known tectonic data for this region it is possible to attribute the A and B anomalies to the Ribeirão Preto and Presidente Prudente crustal sutures, respectively. The smaller C anomaly needs further field investigation, but it could be associated with the Três Lagoas crustal suture. It must be emphasised that these sutures are inherited from the Precambrian Basement which had a strong influence on the Phanerozoic evolution in the whole sedimentary and volcanic stratigraphic pile of the Paraná Basin and on the dominant structural lineaments directions developed therein .The A, Band C anomalies are suggestive of renewed uplift as a result of neotectonic action in modern times.

As rochas intrusivas da Formação Serra Geral na Porção leste da Bacia do Paraná no Estado de São Paulo: Aspectos petrográficos e geoquímicos - Resultados preliminares

The purpose of this paper is to present preliminary aspects of the petrography and chemistry of intrusive rocks (sills and dykes) from the eastern portion of the Parana Basin in the State of Säo Paulo. Data from 80 samples of the region show a subaphyric and subophitic nature and have plagioclase (25-50%), augite (3-39%), pigeonite (0-10%) and magnetite (4-20%) as an essential minerals. Apatite and quartz are present as accessory minerals. The geochemical data of intrusive rocks show a basic to intermediate composition (48% < SiO 2 < 56%) and a high Ti nature (TiO 2 > 2%). Based on the minor and trace composition of the intrusive rocks, two different magma types were recognized, named Paranapanema and Pitanga. The spatial distribution of these magma types is not alleatory in the studied region. The intrusive rocks of Pitanga magma type are displayed in the Campinas-Paulinia region, while the Paranapanema magma type cover a large region above that one, between Rio Claro and Cajuru. Furthermore, the chemical composition of the lava flows of the Serra Geral Formation, sampled in this work, reveals a magma of Urubici type. So, the intrusive rocks of the eastern portion of the of State Säo Paulo are not the extension of the lava flows, or they aren't a portions which don't reach the surface.

Variação sazonal de alguns parâmetros físicos e químicos em três rios pertencentes a uma bacia de drenagem na região centro-sul do Estado do Paraná, Sul do Brasil

Three small rivers belonging to the Rio das Pedras basin, located in the mid-southern region of Paraná state, were studied in order to evaluate the seasonal variation pattern of some physical and chemical parameters. Monthly samplings were carried out from April 2004 to March 2005. The following limnological parameters were measured: water temperature, specific conductance, oxygen saturation, pH, turbidity, current velocity and depth. The waters of the Rio das Pedras basin presented very peculiar characteristics, showing typical seasonal patterns for some of the studied limnological variables. An Analysis of Variance (Anova) showed significant differences only for pH and depth among streams. A Principal Component Analysis (PCA) showed a weak tendency to form groups based on seasons instead of sampling sites. The results, in general, indicate that temporal variations of the environmental parameters analyzed were not sufficient to draw a clear seasonal pattern in the Rio das Pedras basin. Most likely, the lack of an obvious seasonal pattern has been provoked by a particular regional precipitation regime, where rains are frequent and well-distributed throughout the year.

Litogeoquímica E aspectos Petrogenéticos dos basaltos da Província Magmática do Paraná na porção centro-norte do Estado de São Paulo

The petrographic and geochemical characterization of flood basalts of Serra Geral Formation are here presented. The investigated areas are situated in four different regions of São Paulo state: Jaú, Ribeirão Preto, Franca and Fernandópolis. They represent almost the total area of outcrops of basalts in the São Paulo State. The petrographical data reveals that these rocks are constituted mainly by plagioclase (30-40%), pyroxenes, augite and pigeonita (20-30%) and magnetite (5-15%), and show a intergranular texture and its varieties intersertal, hialophitic and pilotaxitic. The geochemical data show a basic and tholeiitic affinity of the studied basalts, with high-Ti content (TiO2 > 1.8%), typical of the northern region of Paraná Basin. Three different magma-types were recognized: Paranapanema, Urubici and Pitanga. The first magma-type is concentrated in the Fernandópolis region, the second in the Franca region, and the Pitanga occurs in the Ribeirão Preto and Jaú regions. The distribution patterns of these magma-types and the detailed study of geochemical data showed that they are, probably, generated by a melting of a continental lithospheric mantle.

Contexto geológico e estrutural do Maciço Rio Apa, sul do Cráton amazônico - MS

Rio Apa Massif crops out in the Mato Grosso do Sul state and corresponds to the southeastern portion of the Amazonian Craton dominantly Paleoproterozoic in age. Rio Apa Complex is oldest and it is composed mainly by migmatitic orthogneisses, beyond amphybolites, tonalities and granodiorite. Alto Tererê Group is composed by schists, biotitemuscovite gneisses and micaceous quartzites generally rich in garnets, beyond metabasic rocks of low amphibolite facies. The Amoguijá Group is constituted by Alumiador Intrusive Suite, which is represented by a sieno to monzogranitic batholith and Serra da Bocaina Volcanic Suite composed of volcanoclastic rocks of alkali riolites to monzoriolites compositions and pyroclastic products. Overlaying towards East and South occurs Neoproterozoic metasedimentary rocks from the Paraguai Folded Belt (Cuiabá, Corumbá and Jacadigo Groups - Urucum Formation). Structural-metamorphic framewok is identified by five deformational phases but the actual tectonic and metamorphic structure shows the superposed tectonic array of the Paraguai Folded Belt. Rocks from Rio Apa Complex, Alto Tererê Group and Amoguijá Group record an older structural evolution defined by (Dn-1 and Dn). The deformational phases (Dn+1 and Dn+2) are visible mainly in rocks of Paraguai Folded Belt beyond the last deformation (Dn+3) that imprints all sequences.

Grupo itararé (P - C da bacia do Paraná) nas regiões de Limeira e Piracicaba - SP: Contribuição ao estudo das litofácies

The Permian-Carboniferous Itararé Group is one complexe lithostratigraphic unit of the Paraná Basin, southeastern Brazil, typically marked by discontinuity of its lithofacies. Under the exploratory point of view, the unit represents one of the most significant intervals of the basin, since several occurrences of mineral and energetic resources are associated to it, as groundwater, petroleum and coal. The prospection and exploitation of these resources depend on a good understanding of the stratigraphic architecture and the paleogeography. There are many contributions on the specialized literature which deal with this subject, although the regions of Limeira and Piracicaba (superior portion of the unit) still lack new investigations, which may contribute to the understanding of its lithofacies and related sedimentary processes. It was analyzed the sedimentary sets pilling up, followed by stratigraphic correlations between the two regions. Moreover, from sedimentary structures, it was made paleocurrent measurement with the purpose of obtaining indicative patterns of the sedimentary polarity, contributing for the comprehension of the paleogeography. Recent studies in the Domo de Pitanga region (between Rio Claro and Piracicaba cities) and in the Corumbataí river drainage basin, were taken also as basis for possible correlations. It was obtained a frame of the lithofacies arrangement, their vertical and lateral relations, as well as their depositional polarities.

Influência do arcabouço hidroestratigráfico nas ocorrências de arsênio em águas subterrâneas ao longo do corredor termal do rio Uruguai (Argentina - Brasil - Uruguai)

The Thermal Corridor of Uruguay River is located in the triple border of Argentine, Brazil and Uruguay, and shows an intense economic thermal tourism activity, mainly based on groundwaters from Guarani Aquifer System (GAS). Recent studies have pointed out the occurrence of high concentrations of arsenic (>10 μg/L) in GAS groundwater in this area. The complex geological and hydrogeological framework in the area is associated to the Paraná Basin geological evolution south of the Assuncion-Rio Grande Arch; it encompass paleozoic marine sequences and continental sequences permian/eotriassic to mesozoic in age, which are covered by basaltic lavas of Serra Geral Formation. Iron oxide coatings have been described in sandstones of Buena Vista and Sanga do Cabral formations, which underlie GAS units. Arsenic occurrence is associated to sodium bicarbonate groundwater with pH values over 8.0. Arsenic is released to groundwater by desorption from iron oxides/hydroxides, as result of the higher pH of these waters, indicating that arsenic is released from the units that underlie GAS units. Increase in chromium and uranium concentrations are also related to high pH groundwaters, thus indicating special care on using groundwater from this region.

Suíte vulcânica serra da bocaina, grupo amoguijá, maciço rio apa-MS

The Rio Apa Massif corresponds to the southeastern portion of the Amazonian Craton and crops out in the Mato Grosso do Sul State, Brazil. It is constituted by rocks of paleoproterozoic age of Rio Apa Complex, Alto Tererê Group and the plutonic-volcanic suites of the Amoguijá Group, subdivided in Alumiador Intrusive suits and Serra da Bocaina Volcanic. The Volcanic Suite is represented by São Francisco and Bocaina mountains and is constituted by terms of the composition of alkali - rhyolitic to rhyolitic, including in minor amounts riodacite, andesite and dacite. It consists of a variety of textual subvolcanic rocks, volcanic and varied volcanoclastics. The pyroclastic deposits are very expressive and consist of pyroclastic particle immerse in aphanitic matrix, fine grained or amorphous, where quartz, feldspar, chlorite, sericite, microlithes of carbonate, sparse spherulites and reliquiar volcanic glass can be distinguished. The pyroclastic rocks are represented by breccias, ignimbrites, agglomerate, tuffs, lapillistones and pumices and contain commonly vitroclasts, lithoclasts and crystalloclasts, pumices, fiammes, glass shards, spherulites, vesicles and amygdales. They are calc-alkaline rocks with dominant peraluminous character high to middle potassium series and define a sin-colisional dominant tectonic and are genetically associated to the evolution of the Amoguijá Magmatic Arc.

Análise dos parâmetros morfométricos da bacia do Rio Preto, Serra do Espinhaço (Minas Gerais, Brasil)

The Rio Preto Hydrographic Basin (RPHB) is located in the North-central portion of the state of Minas Gerais, Brazil, 30 km ENE of the city of Diamantina. The sources of the stream of that name are found in the Rio Preto State Park, which has an area of 10,755 hectares. The total area, perimeter, extension, and axial length of the RPHB, as well as other morphometric characteristics, with emphasis on shape indexes, were obtained with the help of the ArcGis 9.2 program. The cartographic data were taken from digitalized topographic charts in a scale of 1:100,000 of the Brazilian Geographical Institute (IBGE). The measured drainage area is of 389.3 km2 and the perimeter is 136.9 km. Due to structural influence, the shape of the RPHB is irrgular and elongated, with drainage developed in a dendritic and parallel pattern. Those characteristics were checked by means of the compaxity coefficient and the shape factor. The first one was estimated in 1.94, what implies that the basin is not subject to fast flooding in years with normal precipitation. The high degree of fluvial downcutting of the basin is confirmed by the fact that it is a 5th order basin, it presents a significant branching rate and a medium drainage density.

Magmatismo do batólito rapakivi Rio Branco, sw do Cráton Amazônico (MT)

Rio Branco Rapakivi Batholith is located on the southwestern portion of the Amazonian Craton in Mato Grosso and belongs to the Cachoeirinha Tectonic Domain, part of the Rio Negro-Juruena Geochronological Province, Central Brasil. The batholith is constituted by microgabbros to quartz microgabbros and microdiorites to quartz microdiorites, middle to fine-grained equigranular to porphyritic varieties form the Rio Branco Intrusive Basic Suite, showing a discontinuous distribution and located near the margins of the intrusion.Majorly constituted by porphyritic, granophyric and isotropic facies of Rio Branco Intrusive Acid Suit which is composed by older dark red rapakivi monzogranites to quartz monzonites and quartz sienites (1403±0.6 Ma) and the younger red rapakivi leuco-monzogranites (1382±49 Ma) and late equigranular to pegmatitic monzogranites. The magmatism is constituted by two distinct magmas related to the end of the collisional event of Cachoeirinha Orogeny, one with alkaline basalts generated in an intraplate environment and the other postorogenic to anorogenic with peraluminous to metaluminous compositions and define a high-K calc-alkaline to shoshonitic magmatism in transition among the I- and A-types. The contacts are marked by extensive mafic sills and dikes of alkaline basalts derived from intraplate environment of the Salto do Céu Intrusive Basic Suite (±808 Ma) associate to the Sunsás-Aguapei Orogenic Belt and metasedimentary rocks of the Aguapeí Grup.

Mudanças ontogenéticas na dieta de Oreochromis niloticus and Tilapia rendalli da represa de Barra Bonita (rio Tietê, Estado de São Paulo, Brasil)

The Nile Tilapia, Oreochromis niloticus, and the Congo Tilapia, Tilapia rendalli, are important members of the African cichlids, and have been introduced to many Brazilian lakes and reservoirs. These species exhibit a large feeding flexibility and may modify their habits during their growth. In the Barra Bonita reservoir, these species are well adapted, representing more than 80% of fish. This study aimed to analyze ontogenetic variation with regard to the diet of these species in this important reservoir. Samples were taken monthly, from March 2007 to February 2008, in Anhembi, São Paulo State. Both species were analyzed by grouping individuals according to size classes. The coexistence of these species was observed in this environment, to which fish were introduced, as well as discreet differences in diet, being that Oreochromis niloticus was considered as an detritivorous, since the detritus was constant in the diet of almost all size classes, and presents some changes in its diet according to the different size classes. While T. rendalli may was defined as herbivorous, and the contribution of food resources to the diet of T. rendalli seems to be different from that of O. niloticus along the size classes.

Suíte plutônica Alumiador, grupo Amonguijá, maciço rio apa - MS

The Rio Apa Massif corresponds the southern portion of the Amazon Craton and is located in the southwest of Mato Grosso do Sul State. It consists on Paleoproterozoic rocks of Rio Apa Complex, Alto Tererê Group and Amonguijá Group, is subdivided into Alumiador Plutonic Suite and Serra da Bocaina Volcanic Suite. The volcanic suite is comprises sub volcanic, volcanic and varied volcanoclastics rocks with composition ranging from alkali-rhyolitic to rhyolite types. The plutonic suite corresponds to an N-S elongated batholith and is characterized by four main segments delimited by NW-SE faults. The southern and central main segments, discussed in this paper, are characterized by the following petrographic facies: medium to fine grained hornblende-biotite monzogranites, coarse grained biotite monzogranites, graphic biotite sienogranites and muscovite sienogranites and the northern segment is contemporaneous and is composed of two different sequences of rocks, one acid and another of basic to ultrabasic composition. The southern and central segment consists of to chemically compatible rocks with the types I and A Granites. These are calc-alkaline rocks of high potassium to the shoshonitic and subalkaline. Constitute sin-collisional granites of metaluminous the peraluminous characters of the Amonguijá Magmatic Arc, but they exhibit late litotypes with chemical characteristics of post tectonic granites from intraplate environment.