bluuebunny/crossref_metadata_2025 huggingface dataset:
O Controle da Deriva Litorânea no Desenvolvimento do Campo de Dunas e da Antepraia no Litoral Médio do Rio Grande do Sul
Authors: TOLDO JR ELÍRIO , ALMEIDA LUIZ , ABSALONSEN LUCIANO , GRUBER NELSON
Published: April 2019

Zones of erosion and accretion were delimited by comparing a DGPS shoreline mapping in 1997 and the beach line reproduced from the army chart collection of 1975. The results show extensive shore retreat along of Rio Grande do Sul central coast, while accretion was observed in Mostardas and Dunas Altas beach. Mathematical estimative of the regional longshore transport potential along the Rio Grande do Sul coast, a 630-km long holocenic fine sand barrier, resulted in a large net northward annual sand volume. Additionally, the estimated potential of sediment transport based on the CERC formula predicts a substantial variation of the energy flux into the surf zone, due to little changes in shoreline alignments and in the potential alongshore sediment transport. The reduction in the sediment flux due to changes in the shoreline alignment produce a jam in the longshore transport, meaning that part of the sediment arriving from the upstream stretch may be deposited or diverted offshore by coastal jet. Based on that, it is possible that changes in the net longshore sand transport are responsible for the increase in the shoreface width from less than 1 km to more than 3 km in Mostardas beach and Dunas Altas beach. Interesting to note that wider dune fields are associated to those beaches where shoreface is also wider. In this way, the volume of longshore sand transport and the sediment jam provide by changes on shoreline alignment in Mostardas and Dunas Altas beaches are important for both coastal dune fields and shoreface width.
Sedimentologia e Estratigrafia de Rampa Arenosa - Praia Mole (SC) - e sua Correlação com Eventos Paleoclimáticos Globais
Authors: PAISANI JULIO CESAR
Published: April 2019

The term sand ramp has been used to define a deposit constituted of eolian, fluvial, of hill-slope facies and with paleosols established in topographical obstacle. The occurrence of sand ramp is little known in the Brazilian coast. Sand ramps have been identified in the east band in Santa Catarina Island and studied in the Joaquina and Mole Beach. The present study focuses on facies, paleosols genesis, classification and correlation with global paleoclimatic events. There are still some doubts whether the interpretations can be taken as common properties of sand ramps in the eastern band of Santa Catarina Island. The present article shows the stratigraphy of sand ramp in Mole Beach. It argues if dissipation facies predominate and if there are colluvial paleosols. We established the chronology from the stratigraphic record using the luminiscence method and the correlation of the layers and paleosols with global paleoclimatic events. We have verified the deposit of the sand ramp in Mole Beach shows aeolian, of dissipation beds and paleosols. The aeolian beds are predominant and thicker than the dissipation beds. The paleoclimatic meaning of the dissipation beds is little understood. A paleolatosol and two paleoargisols constituted by fines generated by the alteration of heavy minerals of aeolian beds were individualized. The first should have been developed during the interstadial period (marine isotope stage 5c), while the other two were formed from the beginning to the middle of the current interglacial (marine isotope stage 1). The stratigraphic record of the area showed that the deposit of the sand ramp developed 124,000 yr B.P., between the two maximum last transgressions in the Brazilian coast, being much more recent than once thougth and corresponds with known data of the coastal evolution of the Santa Catarina Island.
Evolução do Manto de Intemperismo Laterítico Rico em Fosfatos na Ilha de Itacupim (PA) - Mineralogia, Micromorfologia e Geoquímica
Authors: DE TOLEDO MARIA CRISTINA MOTTA , DE OLIVEIRA SONIA BARROS , DA COSTA MARCONDES LIMA , PASSOS CAMILA , DE ALMEIDA HENRIQUE DINIZ
Published: April 2019

The lateritic mantle overlying ultramafic rocks at Itacupim Island (state of Pará, northern Brazil) comprises 5 horizons. From bottom to top they are: (1) altered rock (hornblende, phlogopite, apatite, magnetite, fissural wavellite, and smaller amounts of smectite or kaolinite), (2) a smectitic saprolite (smectite, wavellite, goethite, and traces of hornblende), a kaolinitic saprolite (kaolinite, wavellite, goethite, and traces of phlogopite), a phosphatic duricrust (crandallite, goethite and hematite), and a ferruginous duricrust (hematite, goethite and crandallite). The mineralogical and chemical composition of the saprolitic and duricrust horizons indicate a discontinuity in the weathering evolution: the P-rich crandallitic duricrusts cannot be derived from the P-poor wavellitic saprolites. Most probably, the duricrusts developed during an earlier stage of the weathering evolution, under a drier climate, when the hypogene phosphates (wavellite and apatite) transformed into crandallite. Under subsequent more humid conditions, the weathering alteration of the parent rock led to the dissolution of the hypogene phosphates, resulting in the P-depleted saprolites.
O uso de Imagens do Sensor Aster no Mapeamento de Unidades Vulcano- Sedimentares do Platô da Ramada, Vila Nova do Sul, RS
Authors: SOMMER JUSSARA ALVES PINHEIRO , DE LIMA EVANDRO FERNANDES , SALDANHA DEJANIRA LUDERITZ , SOMMER CARLOS AUGUSTO , PIEROSAN RONALDO
Published: April 2019

The remote sensing products which are generated by orbitals sensors of middle spatial and spectral resolution and the development of new technique of digital image processing has been a auxiliary tool in the basic geological surveys. In this work was utilized images obtained from the ASTER sensor (Advanced Spaceborne Thermal Emission and Reflection Radiometer) to identify the lithologies in the Ramada Plateau area, situated closed to Vila Nova do Sul town, in the southernmost Brazil, giving emphasis to the volcanic sequence of the plateau and the encase sedimentary rocks unit. The volcanic unit represent a important part of the Neoproterozoic alkaline magmatism in the Sul-rio-grandense Shield and is interpreted as one of the volcanic cycles of the post-collisional period of Brasiliano Cycle in the southern Brazil. The selective principal component analysis technique was used in the digital image processing, because it provided the best results enhancing the existent spectral differences of the studied lithologies. In this processing were utilized only two spectral bands to reduce the data dimensionality, permitting a better interpretation of them. The first generated image (PC1) concentrate the common information of the two bands (albedo and topographic shading), while PC2 image present the differential information of the scene, representing the spectral contrast of the two original bands. From this technique was generated a color composite image from the PC’s2 images of the pair of bands 4-5 (R), 3-4 (G) and 8-9 (B). This image has shown the spectral differences between volcanic rocks of the Ramada Plateau and the sedimentary rocks of the Maricá Group and its individualization in two sub-units, mainly considering the concentration of rhyolitic dykes and sills in the north of the area. In this study was identify too in the southwestern portion of the Ramada Plateau, a dioritic intrusive body.
Estratigrafia de Seqüências Aplicada à Caracterização de Aqüíferos: um Estudo de Caso na Área de Candiota, Rio Grande Do Sul
Authors: HOLZ MICHAEL , KUCHLE JULIANO , BISCHOFF ALAN PATRICK , DOS REIS PAULA DARIVA , PHILIPP RUY PAULO
Published: April 2019

Detailed stratigraphic analysis of the Early Permian (Artinskian/Kungurian) succession of the intracratonic Paraná Basin in southernmost Brazil has been applied focusing stratigraphic characterization of potential aquifers. In the study area, the counties of Candiota and Hulha Negra, in the southwestern region of Rio Grande do Sul state, the sedimentary succession (Itararé, Rio Bonito and Palermo units) is interpreted to have been formed in a shallow, wave-dominated sea, originated mainly in a mixed (tide and wave) influenced estuary setting. Four main depositional systems have been recognized: alluvial fan, fluvial-dominated delta, lagoonal estuary and barrier/shoreface. The regional correlation of the lithofacies within the different depositional systems has led to a high-resolution stratigraphic framework, with three third-order depositional sequences (i.e., unconformity-bounded depositional packages formed during a complete cycle of falling and rising base level). The main sandbodies occur within sequence 2 which is formed by seven fouthorder parasequences, and at the base of the third sequence. Under the viewpoint of groundwater prospecting, the best sandbodies occur within parasequences 1,2 4 and 7. Based upon the stratigraphic characterization, optimal borehole locations are given, as well as estimatives on productive dephs and water volume.
Análise Tecnológica dos Granitos Cerro do Sandi e Bela Vista, Piratini-RS Para Uso Como Rocha Ornamental
Authors: PHILIPP RUY PAULO , PINHEIRO CÁSSIO ALEXANDRE RODRIGUES , GONZATTI CLÓVIS , DE CAMPOS ROBERTO SACKS , REMUS MARCUS VINICIUS DORNELES
Published: April 2019

Cerro do Sandi and Bela Vista granites occur in the Piratini region and belong to Dom Feliciano Suite. This suite is the most recent magmatic episode of the Pelotas batholith construction. The granitic massifs have elongate forms along NE-SW direction and constitute a positive relief of aligned crysts. Mapping of geological, structural and superficial deposits indicated the presence of outcrops and areas dominated by boulders with potential for exploration of blocks for dimensional stones. Petrography and technological essays confirmed favorable results to this utilization. Bela Vista Granite presents high mechanical resistance and low abrasion, qualities that recommended its utilization as external and internal covering. Cerro do Sandi Granite showed physical indexes and ultrasonic propagation velocity characteristic of rocks without weathering alteration. However, in the alterability essay this granite showed incipient modification of color and minimal loss of material. These characteristics limit the utilization of this granite as external and internal floor.
Previsão de Ondas Oceânicas por Ensemble: Uma Revisão e Estudo de Caso
Authors: FARINA LEANDRO
Published: April 2019

The ensemble numerical prediction of ocean waves is considered and all published works on this new topic in Geosciences are reviewed. A Wave Ensemble Prediction System is described where a global third-generation wave model is adopted. Twenty members are generated by a method based on Empirical Orthogonal Functions and a particular realistic case where several extreme wave events occurred is analysed.
Geoquímica de Minerais Detríticos em Estudos de Proveniência: Uma Revisão
Authors: DE BARROS CARLA ENNES , NARDI LAURO VALENTIM STOLL , DILLENBURG SERGIO REBELLO
Published: April 2019

The chemical composition of detrital minerals in sediments has become a powerful tool for provenance studies, particularly in the last decades with the improvement of analytical techniques for mineral grains. Major and trace element contents of igneous and metamorphic minerals can reveal the characteristics of their original sources, mainly with respect to their geochemical affinity, geotectonic setting and the physical parameters that controlled their crystallization. The proportions of major elements in pyroxenes and amphiboles can be used for the identification of their igneous or metamorphic origin, for the definition of their magmatic affiliation, and for the discussion of the probable tectonic setting where they were generated. Metamorphic and igneous zircons can be distinguished by REE patterns or U and Th contents. Magmatic zircons from different geotectonic settings can show different concentrations of REE, Nb, Hf and Y. Magmatic garnets from granites typically show high Mn contents, and can be distinguished from metamorphic ones or from garnets of ultramafic rocks mainly through their major element composition. Compositional zoning of garnets are indicative of their metamorphic or igneous character. Magmatic, metamorphic and hydrothermal epidotes can be distinguished by their chemical composition, as well. Several other minerals, such as apatite, tourmaline, rutile, titanite, and feldspars can indicate, through their chemical composition, the probable rock that could have produced them. The integration of geochemical data on detrital minerals with other usual tools of sedimentary petrology is certainly the most efficient approach for investigating the provenance of sediments.
Magmatic Epidote and Amphibole from the Rio Espinharas Hybrid Complex, Northeastern Brazil
Authors: CAMPOS THOMAS , NEIVA ANA MARGARIDA , NARDI LAURO VALENTIM STOLL , PEREIRA LUCIANO SCHAEFFER , BONZANINI LEONARDO FRAGA , PETTA REINALDO , MEYER FRANZ MICHAEL
Published: April 2019

The petrography and chemistry of epidote and amphibole from the Rio Espinharas hybrid complex (REHC), northeastern Brazil are reported. The Rio Espinharas complex is composed of an intimate association of diorite to shoshonitic metaluminous quartzmonzonite to slightly peraluminous syenogranite. The epidote shows four textural relationships: three are primary and one is resulting from sub-solidus reaction. Euhedral epidote is dispersed and associated mainly with biotite and amphibole. In some cases euhedral crystals of the epidote contain allanite cores, which are subhedral to anhedral and constitute in average less than 20% of the whole grain. The contact between primary epidote and plagioclase is corroded, suggesting reaction with the host-magma. Secondary anhedral epidote is rare and results from plagioclase alteration. The preservation of magmatic epidote in granitic rocks emplaced in the upper crust is attributed to rapid magma ascent, which implies fast upward transport probably by dyking associated to shear zone. The REHC occurs between two transcurrent faults that impose an elongated shape, suggesting that magma filled fractures. The time of 14 years required for dissolution zones of 0.15 mm width of epidote on porphyritic quartz monzonite, corresponds to an average ascent rate of ≥ 700 m year-1 from 7.1 to 2.9 kbar.
Análise Geoquímica dos Sedimentos de Fundo do Arroio do Salso, Porto Alegre - RS - Brasil
Authors: SOARES MARIA CRISTINA CERVEIRA , MIZUSAKI ANA MARIA PIMENTEL , GUERRA TERESINHA , VIGNOL MARIA LÍDIA
Published: April 2019

This paper presents the results of a study performed on bedload samples from the Salso Creek in the Porto Alegre City (Rio Grande do Sul State) rural area where agricultural and pastoral activities are carried out within urban areas. Sediment sampling took place on the 16th September 2001 (winter) and 21th January 2002 (summer), at five sites along the Salso Creek. The Salso Creek bed load changes from granules and pebbles (upstream reaches), through coarse- to medium-grained sand (mid reaches) to fine-to very fine-grained sand in the Salso Creek mouth region. Organic matter content increases throughout the summer low discharge due to the accumulation of the suspended load on the creek bed surface. Grains larger then 0.062 mm feature the following estimated mineralogical composition: feldspar (55-50%), quartz (30-40%), opaque (5-10%) and acessory (5-10%) minerals. Among the finegrained sediments (< 0.062 mm) kaolinite dominates being followed by a minor amount of muscovite/illite as well as quartz, feldspar and smectite traces. The chemical composition of the fine-grained sediments reveals that, among the major (Al, Fe, Mn, Ca, Mg, Na and K) and trace (Cr, Cu, Ni, Pb and Zn) analyzed elements, the Al content is high, probably a result of the kaolinite-rich (Al4(Si4O10)(OH)8) composition of the fine-grained fraction. GeoAccumulation Index calculation shows no significant accumulation of any of the analyzed elements within the finegrained fraction, hence indicating slightly to moderately polluted sediments. On the other hand Contamination Factor computation for the sediments fine-grained fraction pointed out a Cu, Ni and Zn enrichment, indicating considerable to high contamination, especially for those places directly under domestic sewerage influence. These elements are probably being concentrated in the fine-grained fraction of the bed load.
Expansão da Ocupação Urbana de Gramado: Estudo de Caso da Aplicação de Fotografias Aéreas de Pequeno Formato e SIG
Authors: MENDES JÚNIOR CLÁUDIO WILSON , AYUP-ZOUAIN RICARDO NORBERTO
Published: April 2019

Small format vertical aerial photographs were obtained from non metric cameras on small size airplanes, in 1999, and aimed to update a set of six digital cadastral maps from 1984, in the scale of 1:5,000, covering the urban area of Gramado county, located at the northeast region of the Rio Grande do Sul state, Brazil. The photographs were digitized, stored and georeferenced in a Geographic Information System. Afterwards, the perimeters of the new buildings and the boundaries of the urban area districts were digitized on the digital cadastral maps. The updated data of the cadastral maps were elaborated with the purpose to generate thematic analysis and can´t be used for the accurated measure of the mapped buildings. The poligons of the buildings were topologicaly structured by application of GIS, allowing the automatic generation of a centroid to each mapped building. The database query allowed the evaluation of the total number and the localization of the centroids of the buildings, for both date studied. The recorded data were represented by thematic maps of urban occupation expantion, in the scale of 1:25,000. Based on the data obtained, a 164.6 % increase of the total number of buildings was observed, as well as the occupation expantion towards the SE region of the urban area, caused by the major growth of the secundary sector and the major number of new developments in the meridional urban area, that occurred during the past 15 years. Through the interpretation of geographical data, recommendations were proposed for the urban planning of Gramado county.
Metalogênese do Depósito de Cobre Cerro dos Martins, RS -Revisão e Geoquímica Isotópica de SR, S, O e C-
Authors: TONIOLO JOÃO ANGELO , REMUS MARCUS VINICIUS DORNELES , MACAMBIRA MOACIR JOSÉ BUENANO , MOURA CÂNDIDO AUGUSTO VELOSO
Published: April 2019

This paper presents the geology, chemical data, Pb-Pb zircon ages, sulfur, carbon, oxygen, strontium isotopes and fluid inclusions of Cerro dos Martins copper deposit. The deposit is hosted by the Neoproterozoic volcano-sedimentary sequence of the Camaquã Basin in the Rio Grande do Sul Shield, southern Brazil. The ores consist of a set of Cu-sulfide NW-trending veins and disseminations within of the Bom Jardim Group. Chalcocite and bornite are the main ore minerals, whereas carbonates, barite, quartz and hematite are the gangue. The volcanic host rocks show an alkaline affinity. An intrusive quartz-diorite body, also shown alkaline affinity, yield a 550±5 Ma zircon age (initial 87Sr/86Sr of 0,704), which is considered the minimum age of the copper mineralization. The δ34SCDT of sulfides ranges from –6.2 to +0.9‰. Hematite in the mineral paragenesis suggests oxidizing conditions, which would shift the original magmatic sulfur isotopic compositions (δ34S ~ 0‰) to negative values. Barite with δ34SCDT from +9.25 to +10.65‰ may also indicate oxidation due to mixing of a hot rising fluid with cold meteoric water. The δ13CPDB of calcite from gangue, in the range of – 1,90 to – 4,45% is interpreted as originated from mixing sources – magmatic and fluids contaminated by basement marbles. Studies on primary aqueous biphasic fluid inclusions show homogenisation temperatures with average of 215°C. Water in equilibrium with calcite from hydrothermal fluid show calculated values of δ O18 SMOW between 3 and 14‰, suggesting derivation from a magmatic source with some contributions from meteoric water. 87Sr/86Sr from these calcite show values between 0, 7068 – 0, 7087, typical from upper crust. Hence, the Cerro dos Martins copper deposit is interpreted to have had origin by a mixing between a magmatic-hydrotermal fluids related to the alkaline-shoshonitic, post-collisional magmatic event (595-550 Ma) of the Dom Feliciano Orogeny and basement rocks. Exploration models for copper deposits in this shield should consider the alkaline magmatism in the genesis of deposits.
Geologia, Petrografia e Litogeoquímica dos Gnaisses Porto Alegre, RS, Brasil: Implicações Geotectônicas
Authors: PHILIPP RUY PAULO , DE CAMPOS ROBERTO SACKS
Published: April 2019

The Porto Alegre gneiss is a unit composed of granodioritic to monzogranitic gneisses, with subordinate tonalitic and dioritic rocks. The unit represents the basement intruded by several granitic plutons of Neoproterozoic age. The gneisses show an elongate form of NE-SW direction, and constitute a roof pendant. They have composite banding, which results of injection of dioritic and tonalitic melts, followed by a regional metamorphic event of medium to high grade. Three deformational phases are registered in the gneisses, the latest has a mylonitic nature. Their geochemical features are of medium to high-K, slightly peraluminous granodiorites of calc-alkaline affinity. Comparing the Porto Alegre gneisses with metagranitoids of Pinheiro Machado complex, there are several differences, such as the lower values of Al2O3, Na2O and Sr, and higher values of FeO, MgO, MnO and Rb in the former. These differences indicate that there is no correlation between the Porto Alegre gneisses and Pinheiro Machado complex.
Isótopos de Carbono em Filitos Carbonosos da Seqüência Metavulcano- Sedimentar Marmeleiro, Sul de Ibaré, Rio Grande do Sul
Authors: DE OLIVEIRA ALESSANDRO SILVA , PULZ GÊNOVA MARIA , BONGIOLO EVERTON MARQUES , CALARGE LIANE MARIA
Published: April 2019

Carbon isotope ratios for carbonaceous material in the graphite prospect of Marmeleiro Sequence, southwestern of the Sul-rio-grandense Shield, have been determined. The results are approximately constant with δ13C-values between -27 and -24 per mil. These values suggest that the studied carbonaceous rocks were formed from syngenetic organic detritus, which were converted to graphite during metamorphism. The degree of cristallinity of carbonaceous material has also been investigated. The results of X-ray diffraction [d(002): 3.35 - 3.37 Å] indicate this material cristallinity is intermediate between amorphous carbon and fully ordered graphite.
A New Devonian Modiolopsidae (Mollusca: Bivalvia) from the Ponta Grossa Formation, Paraná Basin, Brazil
Authors: KOTZIAN CARLA BENDER
Published: April 2019

This paper describes the bivalve Modiolopsis (?) clarkei n. sp, coming from the Curva I outcrop, Ponta Grossa Formation. The species name was given in honor to J. M. Clarke, who first studied it. This fossil also occurs in the Durazno Group, in Uruguay, reinforcing the correlation between the Devonian Paraná Basin invertebrate fauna with others of the Malvinocaffrik Realm, as suggested by previous authors. The classification of M. (?) clarkei in a typical Ordovician genus or lineage, that can reach the Silurian and Lower Devonian periods, supports an Emsian age to the Curva I outcrop, as have been accepted.
Variabilidade Morfodinâmica das Praias Oceânicas entre Imbé e Arroio do Sal, RS, Brasil
Authors: WESCHENFELDER JAIR , ZOUAIN RICARDO AYUP
Published: April 2019

The morphodynamic variability of the oceanic beaches between Imbé and Arroio do Sal towns, Rio Grande do Sul State, Brazil, was investigated by means of periodic beach profiling combined with the interpretation of granulometric and hydrodynamic regime data. A seasonal trend in the hydrodynamic regime, in the distribution of the sediments and in the morphometric and morphodynamic parameters analyzed, was identified. Seasonality is marked by the dominance of accretionary profiles during the summer and erosional profiles during the winter. These beaches were classified according to their morphodynamic state, as dissipative and intermediate.
Textural Relations of Lamprophyric Mafic Microgranular Enclaves and Petrological Implications for the Genesis of Potassic Syenitic Magmas: the example of Piquiri Syenite, southern Brazil
Authors: CID JORGE PLÁ , NARDI LAURO VALENTIM STOLL , GISBERT PERE ENRIQUE
Published: April 2019

The Neoproterozoic Piquiri Syenite exhibits a large amount of mafic microgranular enclaves (MME) with elliptical-shape and millimeter to centimeter-size dimensions. These enclaves were originated by co-mingling of minettetype lamprophyre and potassic syenite magmas, producing the typical textural features of quenched magmas. They show elongated crystals of diopside and Mg-biotite, and acicular apatite. Early crystallized phases are represented by the same minerals, which occur as phenocrysts (diopside + Mg-biotite) and euhedral smaller crystals (apatite). The textural relationship and the identification of mineral phases as K-clinopyroxene and pyrope in the MME, suggest that mingling started at mantle conditions, when lamprophyric and syenitic magmas were near crystal-free and close to liquidus temperatures. The absence of syenite xenocrysts and chilled-margins in MME, are consistent with the high temperature of co-mingling. Alkali feldspar laths that poikilitically enclose quenched phases, represent late-magmatic mineral phase. The Piquiri Syenite MME represent a quite rare example of co-mingling between lamprophyre and intermediate magmas, and represents important evidence for the genesis of potassic silica-saturated magmas at mantle conditions.
Caraterização por Microssonda Eletrônica dos Teores de Cloro de Apatitas e sua Importância nos Estudos de Traços de Fissão
Authors: MALLMANN GUILHERME , CUPERTINO JOSÉ ANTÔNIO , CHEMALE JR FARID
Published: April 2019

Apatite Fission Track Analysis (AFTA) provides important information for geochronology and is used in different tectonic settings. For example, in the study of sedimentary basins it helps estimate subsidence rates and dates periods of uplift of source areas and tectonic pulses. In geomorphology AFTA also helps to quantify rates of erosion and long-term continental denudation. The chlorine contents in apatites influences the ages obtained from fission track dating. Commonly, apatites with more than 0,4 wt% chlorine yield older ages than fluorapatites (Laslett, et al., 1987), because the stability of the tracks changes as chlorine content increases and consequently chlorine rich-apatites are more resistant to the temperature changes than fluorapatites (Green, 1992). We investigated this problem by first determining the chlorine contents of apatites with the microprobe before apatite fission track dating. We studied four samples of the sandstones from the Reconcavo and Camamu Basins using a total of 198 spots in different apatites. We calibrated CAMECA SX50 electron microprobe using 30 spots from the crystal fragment Durando apatite standard, which has a mean chlorine value of 0,42 wt%. The comparison of the chlorine contents of the apatites of these basins with the ages obtained by AFTA indicates some changes in the individual grains in two samples. These changes are related with the current chlorine content in the apatites, once the individual ages are sometimes distributed as straight line, whose inclination is function of the chlorine content. In the other hand, two samples with modest chlorine content there was not this linear correlation.
Visualização 3D de uma imagem digital: metodologia e potencial cartográfico
Authors: ROS GIOVANA ANGÉLICA , DAL POZ ALUIR PORFÍRIO , HASEGAWA JÚLIO KIYOSHI
Published: April 2019

This article presents a methodology for 3D visualization of a digital image and discusses its cartographic potential. Assuming that a regular DTM (Digital Terrain Model) is available, whose points are connected to form a triangular mesh, a shading methodology is applied triangle-by-triangle. This requires the computation of gray levels of image points corresponding to the pixels of 3D visualization plane, what in turn requires the modeling of the sensor used to acquire the image. Next, a shading model may be used to add artificially an extra effect of shading to the gray levels previously obtained, generating, e.g., shadows along the most elevated slopes opposed to the artificial light source. Finally, a projection model is used to obtain the 3D perception on the visualization plane. Results obtained were sufficient, showing that the 3D visualization methodology has the potential to be used in several cartographic application, as, e.g., in the cartographic revision.
Utilização de um Sistema de Informações Geográficas para o Planejamento Ambiental em Rio Grande, RS - Brasil
Authors: TAGLIANI CARLOS RONEY ARMANINI
Published: April 2019

The social, economics and environmental problems that arise by the fast and inadequate occupation of the coastal zones have required faster decisions and belter rational use of the public administration resources. This work shows the utilization of Geographical Information System IDRISI to environmental planning of Rio Grande county, southern Brazil. Based on digital thematic maps of geology, soils, vegetation. urban sites, legal protection areas and previous knowledge about the ecosystem under consideration, the more appropriated areas for agricultural activities, pine and eucalyptus forestry and waste disposal were mapped. The suitable environmental conditions and the technical and/or environmental restrictions were analysed for each item and then modelled in the computer using the analytical tools of the software. Furthermore, the legal protection areas were classified in conservation and preservation categories according to their environmental characteristics. The results demonstrated the potentiality and feasibility of a Geographical Information System as a powerful tool for organi13tion, analysis and decision making on municipal planning.
Structural and Compositional Evolution of Cr-Spinels and Hornblends, Palma Group, Rio Grande do Sul, Brasil
Authors: HARTMANN LÉO AFRANEO , VASCONCELLOS MARCOS ANTONIO , BITTENCOURT MARIA DE FÁTIMA , CASTRO JOÃO , FABIÃO JULIANA , MONTEIRO ANDRÉIA , PIRES KAREN
Published: April 2019

One amphibolite facies metamorphic event is registered in chromites and hornblendes from the Palma Group serpentinites and meta-andesites, Brazil's southernmost Rio Grande do Sui Slate. Metamorphism was apparently caused by syntectonic injection of voluminous Cambaí Group meta-granitoids and not by post-tectonic Jaguari Granite intrusion. Regional metamorphic hornblendes are in direct contact with magmatic pargasites, which indicates that it was the first metamorphic event in the area. Both hornblendes in Campestre Formation and Crspinels in Cerro da Cruz Formation are little zoned, an indication that only one metamorphic event was of regional extent. Recrystallization to chlorite + epidote greenschist facies parageneses is restricted to shear zones and volumetrically small.
Faciologia da Associação Vulcano-Plutônica Taquarembó, Cambriano do Escudo Sul-rio-grandense, RS - Brasil
Authors: WILDNER WILSON , DE LIMA EVANDRO FERNANDES , DE ROS LUIZ FERNANDO , NARDI LAURO VALENTIM STOLL
Published: April 2019

The Taquarembo Plateau, situated in the southwestern part of Sul-rio-grandense shield, is part of Camaquã Basin, that was formed at the end of the post-collisional stage in Brasiliano/Pan-Africa event, Neoproterozoic in age. This plateau is composed of volcanic and shallow intrusions, related to a silica-saturated alkaline series, ranging from alkaline metaluminous basalt to comendiitic flows, known as Taquarembo Volcano-Plutonic Association. The faciological identification leads to the reconstruction of the volcanic pile, formed from the base to the top by: particulated flows (ignimbrites and reo-ignimbrites); ressedimented syneruptive deposits; surge and fall horizons, closely associated with alkaline metaluminous lava flows (basalts, mugearites, rhyolites); and peralkaline lava flows (comendiites), and shallow intrusions of quarz monzonite and syenite that crosscut the volcanic pile. The facies identification suggests a highly explosive volcanic regime, under sub-aerial condition, in a close association with the feeder necks.
Barras em Pontal em Depósitos Fluviais Antigos: Exemplos nos Registros Geológicos Sul-rio-grandense
Authors: SCHERER CLAITON , LAVINA LUIS , FONSECA MÔNICA , SANTOS LUIS ALBERTO DE OLIVEIRA
Published: April 2019

A point bar is one of the main architectural elements of a fluvial system, commonly described in several sedimentary basins all over the world. However, there are only few examples of this kind of macroform described in Brazilian sedimentary basins. In this paper, two point bars in ancient fluvial deposits outcropping in the Rio Grande do Sul State were described. The Point Bar 1 (PB1) is interpreted as lateral accretion deposits in a bed load channel of moderate to high sinuosity, whose depth was around 5 meters. The PB2 is associated to a mixed load channel, with high sinuosity and depth around 6 meters. Based on geometrical, textural and structural characteristics, differences in depositional and hydrodynamic conditions of the studied paleochannels deposits have been established.
A new Upper Carboniferous Blattoid from Mafra Formation. Itararé group, Paraná Basin, Brazil
Authors: PINTO IRAJÁ DAMIANI , SEDOR FERNANDO ANTONIO
Published: April 2019

A new Blattoid species from Paraná Basin, Anthracoblattina mendesi Pinto et Sedor, sp. nov. is registered for Mafra Formation, Itararé group, Upper Carboniferous, Mafra County, Santa Catarina State. Insects of the same genus and age have been found at Teixeira Soares Formation, Teixeira Soares County, Paraná State, Brazil.
Sedimentação da Desembocadura do canal sul do Rio Amazonas
Authors: CORRÊA IRAN CARLOS STALLIVIERE , ÁVILA MARCELO DEVENUTTE
Published: April 2019

From statistical parameters of the bottom morphology and application of diagrams, as proposed by Sahu (1964), Passega & Beranjee (1969) and Pejrup (1988), the dynamic and sedimentary processes that occur in the Southern channel of the Amazonas river were characterized. The sediments that recover the bottom of the studied area are formed by medium quartz sand that grade, starting from the south river channel, to very fine silts in direction of the outlet of the Pará river, where happens a granulometric inversion. The hydrodynamic of the area is dominated by tidal and fluvial currents as well, partly due the action of winds which control these currents. These factors, associated with the estuarine circulation, are responsible for the transport, redistribution and deposition of the sediments in the Southern Amazonas river channel.
Caracterização dos Componentes da Fração Arenosa(0,500mm/0,250mm) no Canal de São Sebastião (SP)
Authors: BARCELLOS ROBERTO , FURTADO VALDENIR VERONESE
Published: April 2019

The present study investigates the sedimentary dynamics and evaluates the terrigenous or marine inputs to the sediments of São Sebastião Channel (SP), Brazil, through the utilization of sand fraction analysis. Results show, for the summer and winter, in the granulometric fractions of 1Ø and 2 Ø, a decrease of marine contribution from the south to the north of the channel, and from the island side to the continental side. The greater terrigenous influence in the northern portion and in the continental side of the channel is related to lower depths, lower hydrodynamics and the small influence of the shelf water masses. The greater marine influence occurs within the higher depths of the channel axis. This influence is related to shelf water masses penetration through the channel south mouth, increasing the input of marine originated material. The utilization of sand fraction analysis for the São Sebastião Channel sediments is a good tool to identify the type of inputs for the sediments. This technique also complements the interpretations of another parameters, such as grain size geochemical data, allowing a detailed evaluation of sedimentary processes that acts in the study area.
Seismites: origin, criteria of identification and examples from the Quaternary record of Northeastern Brasil
Authors: BEZERRA FRANCISCO HILÁRIO REGO , DA FONSCECA VANILDO PEREIRA , LIMA FILHO FRANCISCO PINHEIRO
Published: April 2019

Seismites are soft-sediment features produced by (paleo)earthquakes. They are formed after sediment deposition, before sediment compaction, and during sudden breakdown of a loosely packet, water saturated grain framework. Fundamental controls on seismite generation are exerted mainly by earthquake size, sediment properties, and water-table depth. Hydroplastic deformation, liquefaction, and fluidization are the three mechanisms related to seismite origin. The most common types of seismites are hydroplastic mixing layers, pillars, pockets, dikes, sills, and folds. Outcrop features are among the most valuable tools for deciphering seismic events in the past. Seismites have been described in many intraplate settings. In northeastern Brazil, earthquake swarms, including events up to 5.2 Mb, induced soft-sediment deformation in at least two historical cases. In this region, seismites occur in the Quaternary record of the Jaguaribe, Açu, and Potengi valleys, where a great variety of types are observed. They are particularly abundant in gravelly and sandy alluvial sediments. But they also occur in deltaic and lagoonal deposits. The study of seismites is particularly useful in areas lacking structural data. Seismite investigation is also important to extent the earthquake record far beyond the instrumental period of seismic observation.
The Holocene paleoenvironment in the Serra Velha region, RS, Brazil through a study of plant succession
Authors: GRALA MÁRCIA MIKLOSKI , LORSCHEITTER MARIA LUISA
Published: April 2019

Palynological studies in the marsh forest of Serra Velha (29º36’S – 51º38’W), Rio Grande do Sul, Brazil, detected a plant succession through hydrosere from a water body already somewhat filled up by herbaceous vegetation at 9800 ± 90 yr BP. The climatic amelioration at the beginning of the Holocene accentuated the filling up process. Later, between 7800 – 7280 ± 60 yr BP, a short phase of significant influence of the forest over the marsh occurred. A new significant expansion of the forest, beginning at about 6000 yr BP took place. This gave rise to the present forest which is represented by many species of the Atlantic rain forest. Compared to the already existing palynological data about the Coastal Plain, it becomes evident that the present Serra Velha forest is older, which seems to indicate the importance of the foothill forests of Serra Geral in forming the present coastal vegetation in Rio Grande do Sul.
Programa de Manejo das Dunas das Praias de Osório - RS
Authors: TABAJARA LUIZ LIBERATO , MARTINS LUIZ ROBERTO SILVA , NICOLDI JOÃO LUIS
Published: April 2019

An intensive and detailed study developed in a pilot area located in the northern portion of Rio Grande do Sul (Brazil) coastal plain, more specifically at Atlântida and Mariápolis resorts, Osório, was carried out in order to establish a dune management program. The study contributes to the beach profile preservation of the studied area and can be divided in three stages: a) diagnosis and mapping; b) dune reconstruction and c) activities aiming at controlling of degradation. For the diagnosis and mapping of the pilot area, aerial survey with small format photographs were taken using a 35-mm camera. The photographs were georeferenced and the images processed through a Geographic Information System – GIS. The technique of dune reconstruction involved replenishment of poor sand delivery areas, stabilization through vegetation profile, reformation of dunes with the aid of machines, and control of wind deflated surfaces through structural methods. Protection of remaining dunes consisted of placing straw tracks ahead of the dune system, detour signals conducting to shoreline transversal to northeast wind and control of erosion through drainage ditches and building of a wall support. Strategic measures were taken to encourage the participation of the population and the support of authorities, and classes on environmental education began to be taught at municipal schools. The basic principle in dune management is to maintain a satisfactory vegetative cover on the foredune, to avoid sand evasion to the continent and its consequent lost from the coastal system. Management of coastal dunes involves the application of sound land use principles, organization of recreational activity and rehabilitation of disturbed dunes.
A Erosão Praial na Costa Atlântica Uruguaia
Authors: PIVEL MARÍA ALEJANDRA GÓMEZ , SPERANSKI NIKOLAI , CALLIARI LAURO JÚLIO
Published: April 2019

The Uruguayan Atlantic coast is wave dominated. It appears as a sequence of beaches built between rocky headlands showing all ranges of morphodynamic behaviors from reflective to dissipative. Several beaches are undergoing erosion. All of them coincide with urbanized areas. In most cases the causes have not been established yet but there is no doubt that human activities have contributed to such problems. This fact raises the question about the nature of the erosion process. Does location of beaches under erosion on urbanized areas prove the man-induced origin of it? This paper discusses the possible factors involved on the beach erosion process. Sediment inputs to the beaches are limited. The inner shelf is likely to be the main source as it is covered with sandy sediments and shows a low gradient relief. The most significant continental source are the gullies although this remains a controversial issue as sediments eroded from them are usually finer than beach sediments. Anyway, as minor as it might be, this input contributes positively to the beach sediment budget. Sediment losses occur mainly by the inland migration of dunes and human activities. The latter includes the occupation of the backshore and frontal dunes, the building of seawalls, revetments and other hard structures to protect the houses, and the fixation of mobile dunes by planting. Pinus and Eucalyptus forests. Possible natural causes for beach erosion include storm surges and concentration of wave energy due to wave refraction. The latter hypothesis arouse in this research from wave refraction diagrams that showed a strong influence of the shelf relief on wave climate.
Geologia e Geoquímica (ETR e Inclusões Fluidas) das Mineralizações (F, BA) da Parte Norte do Distrito Fluorítico de Santa Catrina, Sul do Brasil
Authors: DA ROCHA FLÁVIO FRANÇA , NETO ARTHUR CÉZAR BASTOS
Published: April 2019

This work deals on the fluorite deposits from the Grão Pará (GP) and Rio Bravo Alto (RBA) veins systems both situated at the northern part of Santa Catarina Fluorite District. The GP deposits are controlled by an ancient shear zone. Ore deposition is related to two tectonic phases: (1) dextral transtensive reactivation related to a NE/SW compression; deposition of green-purple massive or coarse banded fluorite; tectonic and hydraulic breccias assign successive transitions from hydrostatic to tectonic regimes; the ore was affected by latter silicification; (2) reactivation as normal fault, related to a extensional tectonic; deposition of purple and yellow banded fluorite, collapse breccias and cocardes. First phase fluorite was deposited at temperatures decreasing from 170º to 120ºC; silicification temperature is around 140ºC. Second phase fluorite was deposited at temperatures between 140º and 120ºC. The fluid inclusions salinity range from 0 to 2% eq. NaCl. The isotopic composition of water from primary fluid inclusions in the fluorite at RBA (δD ͌ -60‰ SMOW) is typical of meteoric water from interior continental region. The RBA fluorite has the same HREE signature as fluorite from the southern district deposits and regional granites. REE and fluid inclusion data reject a link with alkaline magmatism. Fluorine was leached from accessory fluorite of regional granites. The fluorite deposition was connected to a single hydrothermal event correlated to the earlier hydrothermal event described at the southern district.
Análise Fatorial (modo-Q) em estudos quantitativos de nanofósseis calcários do Quaternário Superior em um testemunho da Bacia de Campos, RJ - Brasil
Authors: TOLEDO FELIPE , AYUP-ZOUAIN RICARDO NORBERTO , COSTA KAREN
Published: April 2019

In this paper a Q-mode factor analysis was carried out to study the late Quaternary calcareous nannofossils from core PC-01 (Campos Basin – Brazil). Using CABFAC computer program, two factors were obtained and explain 95,90%, the Factor 1, explain 93,69% and is dominated by speci Florisphaera profunda, wich is restricted to lower euphotic zone, this imply in deep nutricline and thermocline. Factor 2 explain 2,21% and is dominated by species Rabdosphaera clavigera and Gephyrocapsa oceanica, both ralated to shallow nutricline and thermocline. As the core is located mainly in a glacial sequence, it was possible to verify the changes of thermocline and nutricline in this core.
Licófitas Arborescentes in Situ Como Elementos Importantes na Definição de Modelos Deposicionais (Formação Rio Bonito - Bacia do Paraná - Brasil)
Authors: JASPER ANDRÉ , GUERRA-SOMMER MARGOT
Published: April 2019

The study of an assemblage of in situ stumps of arborescents lycopods casts in a coaly sedimentary sequence in Permian (Artinskian – Kungurian) of south brazilian Gondwana, allowed to infer a higromesofilous habita for these plants. The absence of stigmarian-like apendages suggest a root system developed in soils subjected to occasional inundation. These data confirm the depositional model proposed for these successions, related to litoraneous basins (Lagon-barrier System).
Fine Euhedral Banding in Zircon - Metamorphic Enhacement of Igneous Structure
Authors: HARTMANN LÉO , VASCONCELLOS MARCOS , LEITE JAYME , McNAUGHTON NEAL
Published: April 2019

Fine euhedral banding of zircon is usually considered to be associated with magmatic crystallization processes. This is commonly true, but it can also be generated by solid-state replacement along bands in previously more homogeneous crystals. Zircons from the Neoproterozoic Cambaí Complex in southernmost Brazil show abundant evidence to support solid-state replacement. Investigations of more than 135 zircon crystals by Electron Probe Microanalysis and Electron Backscattering techniques show that the solid-state replacement process begins along fractures and expands to broad irregular patches, even forming younger nucleii in some crystals. The replacement continues along crystallographically-controlled bands, enhancing and resembling fine oscillatory igneous zoning. Microprobe analyses indicate that modified zones are enriched in Y, U and T in most BSE-bright bands, but in Hf in some others. The lighter (in BSE) parts in the core are texturally younger than the more homogeneous rims. The mechanisms involved include infiltration along fractures and defect sites and fluid-aided volume diffusion in less defective portions.
Granulitos da Região da Várzea do Capivarita Bloco Encruzilhada do Sul, RS
Authors: DE LIMA EVANDRO FERNANDES , PORCHER CARLOS , WILDNER WILSON
Published: April 2019

This paper deal with recognition of first granulite occurrence in the eastern portion of the Sul-rio-grandense Shield. The granulitic rocks outcrop in the Varzea do Capivarita region, Encruzilhada do Sul block, as gneisses mostly quartzo-feldspatic with orthopyroxene and biotite, associated with supracrustal rocks metamorphosed under upper amphibolite facies conditions. Microprobe analyses show the orthopyroxene as ferrohypersthene. The mineral assemblage of upper amphibolite facies rocks, such as andulazite + sillimanite + biotite + D-feldpars + quartz, points to low pressure conditions of ca. 4 kb. This high grade association is Brasiliano in age, preserved as roof pendants and megaxenoliths within the younger Brasiliano granitoids. On other side, the Santa Maria Chico Granulites Complex, situated in the western portion of Sul-rio-grandense Shield, formed in higher pressure (9,4 kb) during the Paleoproterozoic.