bluuebunny/crossref_metadata_2025 huggingface dataset:
Controles Geológicos das Jazidas de Granitos Ornamentais da Região de Encruzilhada do Sul, RS: Origem das Variedades Comerciais do Granito Encruzilhada do Sul
Authors: PHILIPP RUY PAULO , DE CAMPOS ROBERTO SACKS
Published: April 2019

In the region of Encruzinhada do Sul, it is common the exploration of three faciological varieties of Encruzilhada do Sul Granite: porphyritic, heterogranular coarse and heterogranular very coarse. These varieties are commercially known as Rosa Encruzilhada, Bege Pérola and Coral, respectively. The petrographic analyzes and spatial disposition of the studied types indicated that the textural variations identified present a pattern of lateral zoning and are related mainly to the cooling of the granitic body and secondly to the accumulation of K-feldspar. Porphyritic sieno to monzogranite represents the cooled edges of Encruzilhada granite on embasement metamorphic rocks of Várzea do Capivarita and Arroio dos Ratos complexes. The heterogranular coarse facies represent the core portion of the body and the heterogranular very coarse facies a central and basal of the magmatic chamber, indicated by the accumulation of K-feldspar, followed by the diminishing of plagioclase, quartz and biotite teors. Beyond that, the petrographyc analysis demonstrate that the chromatic variations found in each faciology are related to the state of granite alteration, with colour variations oscilating among white and gray (sane rock), light pink to orange (signs of incipient hydrothermal and weathering alteration) and tones from light brown to very light brown (notable weathering alteration).
Diagnose de Microbiólitos Metálicos em Espécies Vegetais Endêmicas em Solos de Rochas Ultramáficas por Microscopia Eletrônica de Varredura
Authors: CUNHA MARIA DO CARMO LIMA E , MARIATH JORGE ERNESTO DE ARAUJO , MENEGOTTO EGYDIO , FORMOSO MILTON LUIZ LAQUINTINIE
Published: April 2019

The aim of this paper is to investigate by SEM the presence of crystalline forms of noble metals in dehydrated tissues of Scutia buxifolia (Rhamnaceae), Scoparia montevidensis (Scrophulariaceae) and Adiantopsis cf. chlorophylla (Pteridaceae), a endemic vegetation on ultramafic soils from Pedras Pretas, São Sepé, southermost Brazil. Chemical composition of rocks, soils and ash plants were also determined by ICP-MS. The rocks and soils from Pedras Pretas show the expected geochemical pattern of ultramafic ones. Despite the low concentrations of some trace elements and noble metals in ash plants, the BSE images obtained by electron microprobe reveal the presence of semicrystals of Au, Pt, and Ag, besides Ni, Cr, Fe and Ca in xilem parenchyma cells from the species concerned. These preliminary data show the necessity of combination of mineralogical with biogeochemical and physiological investigations in order to demonstrate the importance of these plants in forming biominerals. Moreover, studies about metallic concentrations in plant tissues can contribute to the comprehension of detoxication mechanisms of plants that can be applied for phytoremediation purposes.
Depósitos de Fluxo Piroclástico Primários: Caracterização e Estudo de um Caso no Vulcanismo Ácido Neoproterozóico do Escudo Sul-rio-grandense
Authors: SOMMER CARLOS AUGUSTO , DE LIMA EVANDRO FERNANDES , NARDI LAURO VALENTIM STOLL , DE LIZ JOAQUIM DANIEL , PIEROSAN RONALDO
Published: April 2019

Volcanic deposits can be included in two main groups: coherent and volcaniclastic. The former results from volcanic and sub-volcanic (syn-volcanic intrusions) effusive events, excluding autoclastic portions, and the second group, which is related to deposits constituted by volcanic fragments, encompassing primary deposits (pyroclastic) generated from fragment dispersion through gases and hot vapour, syn-eruptive resedimented deposits, besides volcanogenic sedimentary deposits. Clast transport processes are separated in three broad categories: mass-flow, traction and suspension. Basic concepts that are used in the study of volcanic rocks, classification and characterization of the main subaerial pyroclastic deposits are discussed in this paper, considering lithological and genetic aspects. Lithological aspects are mainly related to composition, components and grain-size of the deposits, while genetic aspects and interpretations are based on clast-forming and depositional processes, allowing understanding about eruption and emplacement conditions. Emphasis is given to pumiceous pyroclastic flow deposits, describing their main textural features and the post-depositional modifications associated to them. The discussed concepts are applied in the reconstruction of the Neoproterozoic pyroclastic flow deposits of two plateaus in the Sul-rio-grandense Shield, southernmost Brazil. The main characteristic of the Taquarembo Plateau is the occurrence of stratified/partially welded ignimbrites and high-grade welded deposits, while massive and crystal-rich ignimbrites are more common in the Ramada Plateau. The facies association of both plateaus suggests a fissural volcanic regime in a subaerial setting, associated to the post-collisional stages of the Brasiliano-Pan African Orogenic Cicle.
Mudanças Topográficas e Sedimentológicas em uma Unidade Soleira- Depressão no Córrego Guavirá, Marechal Cândido Rondon, Paraná
Authors: FERNANDEZ OSCAR VICENTE QUINONEZ
Published: April 2019

Water depth and substrate grain size composition were measured in a riffle-pool unit in the Guavirá stream, municipal district of Marechal Cândido Rondon, western region of Paraná State, Brazil. The objective of the work was to describe the effects of the floods on stream bed topography and sedimentological characteristics of the bottom sediments. During the first survey (December 2000, dry period), the sediment of bottom corresponds to granule and the mean elevation of the bed was of 314,382 m. With the occurrence of the precipitations in January and February 2001, the floods caused oscillations in the bed surface heights (314,177 m in the 2th and 314,403 m in the 3th surveys respectively) and the mean size of the bottom sediments had a continuous decrease: very coarse sand to coarse sand. The oscillation of the bed topography during the rainy period demonstrates that the velocity reversal of the flow during the inundations constantly migrate, fact that can explain erosion and deposition in a same reach during consecutive floods. In spite of bed elevation and sedimentological changes were observed in the riffle-pool unit, any longitudinal migration of the features was not verified even with the occurrence of floods exceeding the bankfull level.
Aplicações de Microscopia Eletrônica de Varredura (MEV) e Sistema de Energia Dispersiva (EDS) no Estudo de Gemas: exemplos brasileiros
Authors: DUARTE LAUREN DA CUNHA , JUCHEM PEDRO LUIZ , PULZ GÊNOVA MARIA , DE BRUM TÂNIA MARA MARTINI , CHODUR NELSON , LICCARDO ANTÔNIO , FISCHER ADRIANE COMIN , ACAUAN ROBERTA BONATTO
Published: April 2019

This paper presents results of SEM and EDS study in some Brazilian gemstones. Emerald from Campos Verdes (GO) contains several mineral inclusions as talc, dolomite, chromite, pyrite, magnetite, etc. Sylvite crystals was firstly identified by SEM/EDS. These salt inclusions suggest percolation of K-bearing fluids during emerald crystallization. Emerald from Campos Verdes present higher concentration of Cr+3 in the outer green zones than in the inner colourless zones, showing that ion is a chromophore in this gemstone. SEM and EDS results combined with optical microscopy analyses demonstrate that amethyst from Rio Grande do Sul State (RS) contain needle-like inclusions of goethite and not cacoxenite and rutile as suggest by other workers. By these techniques it was possible to identify pyrolusite and hollandite as late minerals inside agate and quartz geodes from RS. SEM and EDS data of corundum from Barra Velha (SC) show that silk effect is produced by diaspore inclusions. These techniques also reveal that the asterism in this corundum is produced by empty needle-like channels instead of the presence rutile inclusions as commonly observed in other worldwide deposits. Rounded zircon inclusions are common in corundum from Indaiá, Palmeiras, Caputira and Campo Belo (MG). Sillimanite and/or kyanite inclusions in corundum crystals of secondary deposits from Indaiá suggest a metamorphic origin to this gemstone. Corundum from Caputira also contains several rounded rutile inclusions, which are diagnostic for this occurrence.
Aspectos da Otimização e Processamento de Redes GPS
Authors: MARINI MÁRCIA CRISTINA , MONICO JOÃO FRANCISCO GALERA
Published: April 2019

This paper deals with some aspects which should be taken into account for the densification of geodetic network using GPS technology, specially in the concern of Earth body tide modes, ambiguity resolution and the variance propagation of the network constrains. Based on trials accomplished for a GPS network, some aspects of GPS network optimization and processing are presented. In network optimization, applied to GPS networks, are presented the Zero Order, First Order and Second Order Problems, showing the needs of planning the GPS observations and processing in such a way that one can reach the required accuracy with high reliability and low costs. In the tests to evaluate the need for applying Earth body tide model, it was verified that it is necessary for baselines longer than 200 km for the majority of network application. It was noticed that the ambiguity solution should always be analyzed before accepting a fixed solution as the best, since the presented results demonstrated that some fixed ambiguities are inconsistent. In the processing trials with fixed constrains (without taken into account the precision) or fiducial constrains (with associated precision), it was noticed that the former provided better dispersion values for the new points, however, the last one provided more reliable values, since the new points have associated with themselves the uncertainty of the datum points.
Nanofósseis Calcários Quaternários da Bacia de Campos, Brasil Sistemática e Diagênese Primária
Authors: TOLEDO FELIPE ANTÔNIO DE LIMA , GONÇALVES HELENA MARIA SOUTO , COSTA KAREN BADARACO
Published: April 2019

The analyses of five piston cores (SG91-09/PC-01, SG91-14/PC-04, SG91-14/PC-06, SG91-14/PC08 e SG91- 14/PC09) sampled on Campos Basin - RJ, Brazil, permitted the systematic studies in Quaternary calcareous nannofossils and the description of the primary diagenesis effects on this microfossils using optical microscope and scanning electron microscope. The observation of “in situ” dissolution and reprecipitation of calcium carbonate recorded limitate the systematic studies of calcareous nannofossils and show the importance to use both optical and scaning microscope.
Ocorrência e Significado dos Septos do Embasamento Encontrados nas Suítes Graníticas do Batólito Pelotas, RS, Brasil
Authors: PHILIPP RUY PAULO , MACHADO RÔMULO
Published: April 2019

The Pelotas Batholith situated in the eastern part of Sul-rio-grandense Shield is NE oriented and has dimensions of about 400 x 120 km. It is a granitic belt with six main suites: Pinheiro Machado Suite, Erval Suite, Viamão Suite, Encruzilhada do Sul Suite, Cordilheira Suite and Dom Feliciano Suite. The development of a continental collision whose evolution started by the end of Neoproterozoic, 635-610Ma, and reached 550Ma, is registered in the granitic suites. Most granitoids are syn to late-collisional, which have their emplacement controlled initially by low- to mid-angle shear zones and lately by sub-vertical transcurrent shear zones. The last magmatic events produced alkaline and peralkaline granites and composite (acid and basic) dike swarms represent a postcollisional magmatism.During their ascension and emplacement these granitic units captured basement xenoliths sometimes with dimensions of several kilometers. Based upon petrographic, geochemical and structural data these xenoliths were compared with the metamorphic units that occur outside the batholith. Their similarity suggest that the batholith, in spite of being limited by shear zones, is very close to its original setting. The interaction of xenoliths with the granitic magma produced primary structures that reflect the conditions during the ascent and emplacement of granitic bodies and contribute to the understanding of the geotectonic evolution in the eastern part of Sul-rio-grandense Shield.
Aspectos Pedogeomorfológicos e Mineralógicos de uma Topossequência de Solos Gnáissicos no Complexo Bação – Quadrilátero Ferrífero, MG, Brasil
Authors: FIGUEIREDO MÚCIO DO AMARAL , VARAJÃO ANGÉLICA FORTES DRUMMOND CHICARINO , FABRIS JOSÉ DOMINGOS , LOUTFI IVAN SOARES
Published: April 2019

The mineralogical association of the weathering rocks and their pedogenic process is fundamental in order to understand the erosive susceptibility of the soils. The regolith of the southern area of the Complexo Bação, Quadrilátero Ferrífero, Minas Gerais, was developed from gneiss and has as its predominant characteristic a thick saprolite (around 20 m) overlaid by a solum (A + B horizons) with of less than 3 m thick. This thickness is much thinner than those that frequently occur in the gneiss regolith from tropical and intertropical regions. In the toposequence investigated, the upper slope profile is a cambic soil with a poorly developed B horizon and with many relictal weathered gneiss nodules at the bottom, closer to the saprolite. The mineralogical composition of this B horizon is mainly kaolinite, gibbsite, quartz, hematite and goethite and secondarily pseudomorphous feldspars. The middle slope profile is a latosol with a well developed and thick B horizon. The mineralogical composition of this B horizon is essentially formed by kaolinite, gibbsite, quartz, hematite and goethite. The lower slope profile is a cambic latosol with the presence of relictal gneiss nodules in the B horizon analogously to the B horizon from the upper slope profile. Their mineralogical composition are also similar. The pedogeomorphological evolution of the studied catenary sequence shows that the middle slope profile is allochthonous with an accumulation of colluvial materials that formed a well developed latosol B horizon without primary minerals. The source of the colluvial materials is the upper slope profile. In the lower slope segment the lack of colluvial material suggests a process of incision, with channel and perennial flows that were originated from the adjacent gullies. The incipient fluvial plain that was formed occurs in abrupt altimetric unconformity (declivity rupture) with the lower slope segment.
Variaciones Antropogenicas de las Playas del Sudeste de Buenos Aires, Argentina
Authors: ISLA FEDERICO , BERTOLA GERMAN , FARENGA MARCELO , CORTIZO LUIS
Published: April 2019

The southeastern coast of Buenos Aires Province is subject to natural and critic erosion problems induced mainly by storm tracks from the south. Man tried to minimize these problems by the construction of groin fields and recently by beach-nourishment programs. Sand exploitation was very intense and was prohibited at the end of the eighties (there are still local exploitations where sand accumulation is induced at the base of the southern jetty of the Mar del Plata harbor). Comparing beach surveys carried out at different periods (1983-84, 1991-93 and 1997-2000), significant changes in beach morphodynamics have been detected. At the northern beaches of La Perla region, the prolongation of old groins have caused convex profiles and accumulation of coarser foreshores. The erosive beach of Playa Grande changed dramatically due to nourishment jobs carried out in 1998. Since that time, the beach face became composed of fine sand and has been receding at a faster rate. At the Alfar beach, the interruption of sand mining provoked the accumulation of fine-sand berms. The Chapadmalal beach recorded the more significant morphological changes within this last period (1997-2000). The beaches within the groin field of Miramar city have steep profiles during winter, recovering the berms during the rest of the year, with variations of the coastline of more than 30 m.
Estágios de Mineralização no Depósito Aurífero Pau-a-Pique, Grupo Aguapeí, Sudoeste do Estado de Mato Grosso, Brasil Central - Evidências de Química Mineral e Inclusões Fluidas -
Authors: BARBOZA ELZIO DA SILVA , PULZ GÊNOVA MARIA , RONCHI LUIZ HENRIQUE , JELINEK ANDRÉA RITTER , PINHO FRANCISCO EGÍDIO , QUADROS ÁLVARO PIZZATO
Published: April 2019

The Pau-a-Pique deposit is a small gold prospect in the Southwestern of the Amazonian Craton (Mato Grosso State, Brazil). Ore types comprise quartz veins and disseminations hosted in the mylonitized metaconglomerate (Fortuna Formation, Aguapeí Group) and amphibole-biotite-chlorite mylonite. The native gold is associated with pyrite, pyrrhotite, chalcopyrite, native silver, galena, hematite, magnetite and martite. The aqueous-carbonic (type 1) and aqueous inclusions (type 2) in the quartz veins suggest that ore genesis is related to metamorphic fluids percolation during the late regional shearing. The ore remobilization was promoted by meteoric fluids, which are preserved as aqueous inclusions (type 3) in quartz veins.
Significado Peleoecológico de Alguns Palinomorfos Ocorrentes nos Carvões Eopermianos do Rio Grande do Sul, Sul do Brasil
Authors: KLEPZIG MIRIAN CAZZULO
Published: April 2019

Organic-walled palynomorphs of unknown botanical affinity identified in Early Permian coals from Rio Grande do Sul State, South Brazil, together with spores and pollen grains are analysed in this study. Among the identified taxa are: Tetraporina punctate, Tetraporina horologia, Maculatasporites gondwanensis, Brazilea scissa, Quadrisporites horridus, Quadrisporites lobatus, Pilasporites calculus, Portalites gondwanensis. Besides these palynomorphs, some considerations about Botryococcus braunii, a colonial alga occurring in the associations are presented. The morphological similarity between these microfossils and some algal spores spanning in age from Devonian until Recent permit significant comparisons which improve the knowledge on the spectrum of habitats of these palynomorphs. This study corroborates the idea that the peats, originated in lagoons located in coastal plains, were formed by a biomass composed of spores and pollen grains, plant cuticles, wood remains, fungi and algae, in addition to some forms related to Acritarcha or incertae sedis. Minor marine ingressions would be responsible for the occurrence, in the peat-plant association, of elements related to marine microplankton, like acritarchs, thus confirming the inference of a transitional (barrier/lagoon type) depositional environment for the coals as previously suggested by other authors.
Estimativa de Recursos de Carvão Utilizando Métodos Geoestatísticos
Authors: DA SILVA JORGE LUIS BARBOSA , ZOUAIN RICARDO NORBERTO AYUP
Published: April 2019

This paper presents a geostatical method for resources estimation of a coal seam. The coal seam is refered to as “I” and belongs to Leão-Butiá coal deposit, located at central east region of Rio Grande do Sul State, southernmost Brazil. data set are composed by 182 measures of coal seam thickness obtained by drill holes. To evaluate seam thickness, initially in this work, was approached the basic descriptive statistic about the sampled data set. To continue, spatial continuity analysis was performed and to conclude was carried out an ordinary kriging estimation process. Considering the tree previous process was accomplished a block kriging that allowed estimate mean and variance of seam thickness and extension of sampled total area. With this data it was possible to calculate the coal seam volume. Knowing coal local density and multiplying it by the volume determines coal seam quantities (ton) for which a confidence interval was estimated. To compare estimate and true values a cross validation was made, using the model of kriging and the sampled data set. A histogram is presented to show the average error for the model that should be null to confirm the process.
Análise Geológico-Estrutural do Cinturão Sunsás na Região de Nova Brasilândia - Sudeste de Rondônia
Authors: LUFT JR JOÃO LUIZ , RIZZOTTO GILMAR , CHEMALE JR FARID , DE LIMA EVANDRO FERNANDES
Published: April 2019

The present study is on structural framework of geological units exposed in the Paulo Saldanha topographic sheet situated in the Nova Brasilândia region, Rondônia State. These units outcrops in southwestern portion of Amazonic Craton formed by mobile belts of Mesoproterozoic ages, represented by 1.4 Gy Rondonian and 1.0 Gy Sunsás Orogenic Provinces. The main rocks of study area comprises, in its central portion, the Nova Brasilândia Metaplutonic-volcanic-sedimentary Sequence formed by ortho- and para-derived rocks metamorphosed in upper amphibolites facies, represented by metaturbidites with major intercalation’s of amphibolites and local migmatized granitoid lenses. In southernmost portion, this sequence are dominantly formed by metagabros and amphibolites, with small granitoid bodies of Granito Rio Branco unit highly tectonized by a syn-transpressive regime (D1). At central-south portion, outcrop the Suite Intrusiva Rio Pardo formed by granodiorites syn- to post-transcurrent shear zones, emplaced through spaces generated by transtrative regime (D2) of Rio Branco Transcurrent Shear Zone. All of above units were hard tectonized during Sunsás Orogeny markink the last important period of lithospheric accretion to the southern border of the Amazonic Craton NW-SE and E-W structures strongly control the lithostratigraphic boundaries of Nova Brasilândia Sequence, and Rio Branco and Rio Pardo units, all deformed by the transpressive and transtrative tectonic regime that characterize the Sunsás Orogeny. A hard metamorphic foliation (S1) characterize the NW-SE trending lineaments highly recorded in the metaturbidites of the central Paulo Saldanha sheet. These structures were rotated by E-W trending transcurrent shear zones with sinistral relative movement, formed by Rio Branco and Alvorada shear zones situated in central-southern and northern portion, respectively; and both constituted by milonitic foliation (S2) and stretching lineations (L2) best characterizes at central-southern portions by augengranites of Rio Branco unit. Radiometric data were obtained by U-Pb, Rb-Sr and Sm-Nd methods in the units of the Nova Brasilândia Sequence and from granitoids of Suite Granítica Rio Pardo and Granito Rio Branco. These data interpretation insert the Nova Brasilândia region around 1.1 Gy Sunsás Orogenic Cycle.
Caracterização da Esmeralda de Pirenópolis (Goiás, Brasil Central) por Espectroscopia no Infravermelho (Ftir)
Authors: PULZ GÊNOVA MARIA , BARBOZA ÉLZIO DA SILVA , DE BRUM TANIA MARIA MARTINI , FISCHER ADRIANI , JUCHEM PEDRO LUIZ , BENVENUTTI EDILSON
Published: April 2019

The infrared spectra of two natural samples of powdered emerald from Pirenópolis (Goiás State, Central Brazil) were measured at room temperature (~ 20ºC). Water molecules occur in two different configurations. Three absorption peaks (3656, 3592 and 1624 cm-1) record the vibrations of the type-II H2O. The peak absorption at 3691 cm-1 is assigned to type- I H2O vibrations. In addition, CO2 (2358 cm-1) and CH4 (2927-2925 cm-1) molecules were also detected in the FTIR spectra. These data can be applied to distinguish the Pirenópolis gem from the other Brazilian emeralds as well as its synthetic equivalents.
Beachfront Owners Perception of Beach Erosion along an Armored Shoreline in Southern Brazil
Authors: ESTEVES LUCIANA SLOMP , PIVEL MARIA ALEJANDRA GOMEZ , DA SILVA AMALIA PUCCIENELLI , BARLETTA RODRIGO DO CARMO , VRANJAC MAURO PAQUETE , DE OLIVEIRA ULISSES ROCHA , VANZ ARGEU
Published: April 2019

Brazil has about 8500 km of coastline that is mostly undeveloped. However, the pressure of fast-growing coastal urban centers is already impacting the shore. This paper characterizes shore protection works in Hermenegildo Beach, evaluates their efficiency to protect property against the impact of storm events, and presents the response of beachfront owners to erosion. Hermenegildo is a beach village located 12km north of the border with Uruguay in Rio Grande do Sul, the southernmost state in Brazil. Several factors contribute to beach erosion in Hermenegildo: storm surge, redistribution of wave energy, rising sea level, the presence of an underlying layer of impermeable peat, and human activities. The shoreline is heavily armored with about 61% of beachfront houses protected by revetments (30%), seawalls (18%), or a combination of both (13%). A strong storm struck the Rio Grande do Sul coast in 16 April 1999 and resulted in severe beach erosion and destroyed 22 houses, besides all concrete structures, half of the quarrystone revetments, and 80% of the timber seawalls. Shore protection structures in Hermenegildo are threatened by erosion because: (1) they were built too close to the water, (2) shoreline retreat has been observed, and (3) armoring has reduced beach width. Most of the beachfront owners are aware of the severe beach erosion problem and appear to understand basic coastal dynamics. About 82% of the interviewed beachfront owners lost property due to erosion; 88% subsequently built protection structures to prevent further loss. Surprisingly, 88% of those who did not experience property damage also built defense structures. Armoring is commonly an initiative of beachfront owners who build low-budget structures without consultation by technical experts.
Relative Sea Level Variations and Climatic Evolutuion in Southeastern and Southern Brazil During the Late Holocene
Authors: YBERT JEAN-PIERRE , BISSA WALTER MARESCHI , KUTNER MIRYAN
Published: April 2019

Analysis of organic sediments from a swamp forest on the coastal plain of São Paulo State (southeastern Brazil) has been carried out. Diatom and pollen contents from the same samples were analysed. This study allowed reconstruction of the regional paleoenvironment during the Late Holocene. From at least 4400 to 3250 yr BP the site was a lagoon surrounded by a relatively open forest. At ca. 3250 yr BP, after the retreat of the sea, a swamp forest occupied the area. This swamp forest remains until the present day. It was locally altered during a short period between ca. 1400 and 775 yr BP when, due to a rise in groundwater, a fresh water lake or marsh was formed. The climate was similar to the present during the whole Late Holocene, except for three slightly more humid episodes: 3250-2600, around 2000, and 1400-775 yr BP. No human impact on the vegetation was recorded during the Late Holocene. Our results show that sea level was higher than the present zero level from 4400 to 3250 yr BP, contradicting a widely accepted relative sea level trend that suggests that at least two important negative sea level oscillations occurred during the Holocene (4100-3800 and 3000-2700 yr BP). Conversely, these results tend to confirm more recent studies that propose a continuously declining relative sea level trend. Comparison of our data with those from 24 sites situated in southeastern, southern and central Brazil show that the more humid episodes recorded at Cananéia-Iguape might be correlated with El Niño like events. Trends in climatic evolution during the Late Holocene are opposite at north and south of 20ºS latitude.
Estimativa da Capacidade de Transporte Longitudinal de Sedimentos a partir de Dados de Ondas para a Costa do Rio Grande do Sul
Authors: LIMA SÁVIO FREIRE , ALMEIDA LUIZ EMÍLIO , TOLDO JR ELÍRIO
Published: April 2019

Waves data and a simple mathematical model was used to determine the longshore sediments transport at the Rio Grande do Sul coast. The model was developed by the application of the Energy Flow Method (U.S. Army, 1984), to estimate quantitatively the littoral drift potential for different segments of the coast. The coast was divided in segments or straight lines, which has the same orientation. The coefficient of proportionality between the wave energy and the sediment transport was obtained using beach profile surveys and sediment grain size. The largest drift taxes were of the order of -2.900.000 m3/year and -2.600.000 m3/year for NE, along of the Hermenegildo beach and Between Cassino and Solidão Beach, respectively. reasonable agreement exists between coastal erosion observations in previous studies and the result obtained by this model, which suggests that a predictive capability has been established.
Determinação da Intensidade das Tempestades que atuam no Litoral do Rio Grande do Sul, Brasil
Authors: BARLETTA RODRIGO DO CARMO , CALLIARI LAURO JÚLIO
Published: April 2019

Waves generated by South Atlantic storms are greatly responsible for the beach and coastal erosion verified at the central coast of Rio Grande do Sul State, Brazil. These beaches are classified as intermediate, according to the morphodynamic approach suggested by the “Australian School of Coastal Geomorphology”. The storm wave regime controls the morphodynamic variability of those sandy beaches. Through the classification proposed by Dolan and Davis (1992). South Atlantic storms were classified and related to meteorological systems, considering corresponding beach responses. Out of the 3 year wave gauge storm data analyzed, 54.4% corresponded to Class I (weak), 23% to class II (moderate), 19.25% to class III (significant), 2.75% to class IV (severe) and for class V (extreme), 1 storm was recorded (0.6%). Coincidently, the proportion of storm class frequencies for the 3 year data of South Atlantic storms showed to be similar to the 42 year data studied by Dolan and Davis (1992) for North Atlantic storms. Such classification has proved to be effective for the southern Brazilian coast. Autumn and winter are the storm periods with greatest intensity, wich associated to maximum spring tides and storm surges generate the erosion cicle at this coast. The inverse process is verified to spring and summer, when the accretion cicle takes place. In addiction to this seasonal behavior trend, a continuous process of erosion without further recovering occurred at Conceição Lighthouse and Lagamarzinho beach locations, at rates of 3,6 meter per year and 1 meter per year respectively. The use of such method made possible quantifying storm intensity and establishing its relationship to seasonal erosion processes taking place in the southern Brazilian beaches.
Caracterização de Padrões de Formas de Fundo da Foz do Rio São Francisco
Authors: VITAL HELENICE , DE OLIVEIRA ARNO MASCHMANN , TABOSA WERNER FARKATT
Published: April 2019

On the basis of a regional side-scan sonar survey covering a distance of 12 km on the São Francisco River Mouth between Piaçabuçu and Cabeço-Pontal da Barra (NE Brazil) a variety of bedforms have been distinguished. The river bed morphology of this area can be characterized by three main patterns: dunes, ripples and planar beds. Sand dunes occur as extensive 2D and 3D dune fields. Between Piaçabuçu and Fitinha Island the dunes are asymmetric indicating a sand movement toward the river mouth. These dunes range in height from 1 to 2 m, and in wavelength from 30 to 90 m. Between Fitinha Island and Negra Island large asymmetric dunes with smaller symmetric ones superimposed can be seen, showing tidal influence. At the river mouth, the dunes give place to symmetrical ripples with height smaller than 0,3 m and wavelength shorter than 1 m. The dune and ripples fields can be intercalated by planar beds.
Estrutura de Dissipação: Uma Revisão Conceitual
Authors: PAISANI JULIO CÉSAR
Published: April 2019

The concept of dissipation structures (Bigarella. 1914) refers to processes result introducing morphological, structural and textural modifications imposed to coastal sandy deposits, dunes and beach ridges, during Quaternary global changes. Several structures had been associated to the concept of dissipation structures. although fine textured lenticular contorted structures seems predominant, Twenty-five years later, several doubts persist about the concept. This paper stresses some considerations about de definition of dissipation structures as fine textured lenticular contorted structures ("band of fine") on the basis of the doubts that persist up to nowadays, The main aspects of our analysis deal with: a) the genetic ambiguity of the term: b) the distinction between the different genetic processes: c) the similarity between dissipation structures and pedologic lamellae; d) the generalization of the model associated with the concept. Attention is required when applying the expression dissipation structures to fine textured lenticular contorted structures ("band of fine"). Indeed, this application should be restricted to areas where dissipation processes are well established. In cases other then that, the use of the morphologic expression lamellae is preferable. Also, adjectives may be used to indicate other processes, as iluviation-lamellae for cases when tile accumulation of secondary fine material is verified.
Modos de Transporte de Sedimentos Finos no Estuário do Rio Itajaí, SC
Authors: SCHETTINI CARLOS AUGUSTO FRANÇA , TOLDO JR ELÍRIO ERNESTINO
Published: April 2019

This paper presents an assessment about the modes of fine sediment transport in the Itajaí River estuary. ·The available information to approach a conceptual model is derived from three primary sources: (1) the river sediment delivery; (2) the distribution of salinity and particulate suspended mailer (MPS) along the estuary under influence of different river discharge conditions; and (3) near bed hydro-sedimentological processes. The river sediment delivery was achieved by daily monitoring the water and the suspended sediment discharge, since November 1998 at the Indaial lymnimetric station, which represents about 70 % of the drainage basin. The salinity and MPS distribution in the estuary were obtained through 47 weekly surveys along the estuary when vertical profiles of  these variables were acquired every 1-1,5 km from the mouth to the upper limit of the salt intrusion. The surveys were carried out between November 1998 and November 1999, using an inflatable boat. The results allowed obtain the relationship between the salt wedge extension as function of the river discharge and the estuarine trapping efficiency. The near-bed hydro-sedimenlological processes were assessed through the deployment of an instrument tripod on the estuarine bed al the channel thalweg 4 km upstream from the mouth. The current speed, water level and MPS data were recorded hourly, 1 m above the bottom, from September to November 1999. Based on this data set, two main modes of fine sediment transport in the Itajaí River estuary were identified: a tidal driven and a fluvial driven mode. The tidal driven mode occurs when the river discharge is bellow 200 m3.s-1. Near bottom sediments arc in all erosion-deposition cycle following the semi-diurnal tides and the anomalistic cycle of spring and neap tides, with net sediment transport landwards. During such periods fine sediment is imported from the inner shelf. This mode occurs at time scales of weeks to months. The fluvial driven mode are fully developed when the river discharge exceeds 1,000 m3.s-1. accompanied by suspended sediment load as high as 10,000 ton.day-1. Fluvial advective process fully dominates the sediment transport resulting in zero trapping efficiency.
Evolução Hidrodinâmica e Processos Erosivos Marginais nos Canais do Sistema de Inundação do Alto Rio Paraná, Região Centro-Sul do Brasil
Authors: ROCHA PAULO CÉSAR , DE SOUZA FILHO EDVARD ELIAS , COMUNELLO ÉDER , CORREA GERALDO TERCEIRO
Published: April 2019

This paper intend to contribute on understanding of small part of tropical/subtropical large river fluvial geomorphology: the high Paraná river flood system. The studied area is inserted in Baía River Compartment, characterized of large alluvial plain, in the right margin of high Paraná River, and the greater archipelagoes subdividing the channel in branches with different importance. The intensity of erosive process on the Paraná River banks were studied in four different kinds of channel by 29 points, during a hydrodynamic cycle. The obtained data was still treated with cluster analysis and the correlation through the linear and exponential regression among variables. Results evidenced that the flow velocity and mechanical composition of banks were the main variables of bank erosion rates, and that the another variables, like roots and vegetation, do not had any influence to control the bank erosion. Erosion, accretion and by pass are processes controlled by the Paraná river regime, by shifting of the talweg position and then also controlled by intensity, duration and recurrence of flood.
Origem e Morfologia dos Grão de Quartzo da Cobertura Pedológica na Região Nordeste do Paraná - PR
Authors: GASPARETTO NELSON VICENTE LOVATO , CARVALHO ADILSON
Published: April 2019

The origin of materials which compose the pedological covering in the Northwestern region of the state of Paraná, Brazil, is provided. Research is based on soil distribution along the slopes and in a special way on the morphological characteristics of detrital grains in Caiuá Sandstone quartz and in pedological covering. Fractions (0.500, 0.125 and 0.053mm) of quartz grains were analyzed by scanning electron microscopy. The grains main morphological features are fissures, fractures, dissolution and reprecipitations are associated with the pedological covering. The more chemically changed quartz grains are found in greater depths in the covering cross-sections and as from the lower third section up to the end of the slopes. It is a segment which is constantly saturated in water for a long time during the year. Roundness and sphericity rates decrease according to the size of detrital grains. The presence of similar features in the quartz grains found in both materials confirm that the pedological covering has originated from the Caiuá Sandstone itself.
Mudanças Ambientais Ocorridas entre Abrolhos (BA) e Cabo Frio (RJ) ao Longo do Holoceno, e sua Resposta nas Associações de Foraminíferos
Authors: PASSOS RAQUEL FERNANDA , E SOUsA SILVIA HELENA MELLO , MAHIQUES MICHEL MICHAELOVITCH
Published: April 2019

The assemblages of foraminifera present in eight box cores collected on the continental slope between Abrolhos Bank (BA) and Cabo Frio (RJ), were studied to determine the Holocene paleoceanographical history of the region. This study employed classical techniques for the analysis of paleoceanography, such as stable oxygen isotopes, micropaleontology and AMS 14C datings. Information on sea surface paleotemperature was obtained by measuring the abundance of various taxa of foraminifera: Globigerinoides ruber and Globigerinoides sacculifer as  indicators of warm water masses; Globigerina bulloides and Globigerinita sp. of cold water masses; Globorotalia menardii of warm climate and Globorotalia truncatulinoides of cool climate. The data obtained are in accordance with the results of isotopic analysis and other studies which have been carried out in this region. This study revealed a strong relationship between temperature and primary productivity in the Cabo Frio region, variation in the terrigenous input furnished by the Rio Doce, and occurrence of a regional upwelling southward of the Abrolhos Bank that was associated with sea level changes reflecting events associated with the Last Glacial Maximum (ca. 18 Ka BP).
Clima Seco e Formação de Dunas Eólicas durante o Holoceno Médio em Taquaruçu, Mato Grosso do Sul
Authors: PAROLIN MAURO , STEVAUX JOSÉ CÂNDIDO
Published: April 2019

Holocene sandy deposits interpreted as of eolian origin were studied at Taquaruçu, MS (22º30’ S / 53º20’ W). That area is constituted of hills with 5 to 12 m of height over the regional surface, with lightly asymmetric profile, which, morphologically remind eolian dunes quite dissipated, covered by scattered shrub-arboreal vegetation. The deposits are mainly composed of fine to very fine (35 and 54%), medium quartzose sand (7%), with rare granules in the basal interval and clay (4%). Sediment is almost totally massive, probably, by intensive root bioturbation. Structures generated by dissipation and fluidization were also identified. The studied profiles are very similar and presented a temporal hiatus between 3,3 and 3,7 ka BP. The curve of magnetic susceptibility also displays a coincident inflection with the identified discontinuity in the age curve. It was possible to conclude that the area was submitted to a drier climate than the current during the Middle Holocene. Under this climate there was reduction in the vegetable covering and the consequent mobilization of the sand generating an erosive surface and the formation of small dune field. This dry period at the end of Middle Holocene is also identified in other localities such as in SE and Central area of Brazil, and in NE of Argentina. However, this is the first time that eolian processes of such intensity were described in the studied area, and a revision in the definition of aridity intensity of the short dry period of the Holocene is suggested.
O Gênero Stylatractus Haeckel, 1887 (Radiolaria) em Sedimentos do Pleistoceno Superior - Holoceno da Margem Continental do Rio Grande do Sul
Authors: FAUTH SIMONE BAECKER , LEMOS VALESCA BRASIL
Published: April 2019

The genus Stylatractus Haeckel, 1887 (Radiolaria, Actinommidae) is abundant in upper Pleistocene – Holocene sediments form the Rio Grande do Sul continental margin. Some species of this genus are important Cenozoic biostratigraphic tools. A detailed analysis of the species distribution in Core T18 (GEOMAR VII), as well as an estimate of the chronology of these sediments was done. A revision of Stylatractus is proposed, based on the growth patterns of the Actinommidae skeletons. Three species of Stylatratus were identified in the studied material: Stylatractus neptunus Haeckel, emend., Stylatractus pluto Haeckel n. comb. and Stylatractus nerinus n.sp. The occurrence of Stylatractus nerinus n.sp. suggests that these sediments were deposited in the upper Pleistocene. The Pleistocene-Holocene transition is established by the first occurrence of Stylatractus pluto Haeckel n. comb. The results obtained from Core T18 can be extended to other cores from the Rio Grande do Sul continental margin where the genus was reported.
Evolução temporal da impactação do Sistema Estuarino de Santos - São Vicente (SP,Brasil) analisada através das populações de foraminíferos sub-recentes.
Authors: BONETTI CARLA , EICHLER BEATRIZ BECK , DEBENAY JEAN PIERRE
Published: April 2019

Vertical distribution of benthic foraminiferal species in three shallow sediment cores were used to assess environmental changes in Santos – São Vicente Estuarine System during the last decades. The area was chosen due the diversity and complexity of the anthropogenic agents that have been actuating into this ecosystem since the 1950 decade. Although all analyzed cores presented close species composition, suggesting similar depositional environmental conditions, some variability in species importance along the sedimentary column were observed among then. Particular features of each sampled point were thus related to the environmental transformations to explain that. The results obtained for the Cubatão area suggested an upward transition from strongly restrictive ecological conditions (represented by dominance of Ammotium) to a moderately restrictive ones (with the increase in the relative abundance of other taxa, such as trochaminids). This faunal enrichment was interpreted as a result from a recent re-colonization by mangrove trees in the previously degraded exposed banks (due to reduction of chemical pollutant inputs). The area under influence of Santos Harbor was the one that showed the slightest fluctuations in species distribution. Even so, a possible influence of the periodic dredging of the harbor channel on the variations of Ammotium population along the core can be proposed. Finally, the core sampled at the São Vicente Estuary presented ecological indications of a fast increase of marine confinement, probably related to the intense domestic sewage that reach this sheltered portion of the system. The considerations and hypotheses presented in this research pointed out the great potential in the use of bioindicators as a tool for recent and sub-recent environmental evaluation studies. Nevertheless, the inherent methodological restrictions must be keep in mind and complementary ecological studies need to be conducted in order to allow definitive conclusions.
Mudanças ambientais globais e geoindicadores
Authors: COLTRINARI LYLIAN
Published: April 2019

Global changes are modifications in the Earth System natural environment (physical, chemical, biological) as a consequence of interactions between atmosphere, oceans, cryosphere, and solid Earth, with the biota including humankind. These changes happen on a wide range of time scales, from years to hundreds of millions of years and they are significant features of Earth history. Geoindicators are measures of surface or near – surface geological processes and phenomena that vary significantly over periods of less than 100 years and that provide information meaningful for environmental assessment. They measure geological (mainly abiotic) variations that are important for understanding the terrestrial environment. There has been much interest on the subject of environmental monitoring of ecosystem dynamics and integrity but on the other hand it seems to be forgotten the search for indicators of natural processes and change in soils, landforms, surface, and groundwater that determine the character of the physical environment in general. Natural environmental changes in landscape features result from internal variations in geological and climatic parameters which lead to adjustments in surface processes and materials, and in vegetation. Anthropogenic activities act as external stresses that modify thresholds of stability and hamper understanding geoindicators changes. Procedures to quantify natural and man-made changes and to determine modifications in the recent past are proposed, with special reference to the Brazilian tropics.
Detecção de Mudanças Ambientais na Antártica através de Dados de Sensoriamento Remoto e Mapas Históricos
Authors: ARIGONY NETO JORGE , SIMÕES JEFERSON CARDIA , BREMER ULISSES FRANZ , AQUINO FRANCISCO ELISEU
Published: April 2019

Ice masses in the South Shetland Islands, Antarctica, are relatively thin and near or at the melting pressure point. They are, therefore, very sensitive to climatic variations. This work discusses glaciers retreat observed since 1950s in the Antarctic Specially Managed Area (ASMA) of Admiralty Bay in King George Island. From 1956 to 1979 this area lost 4.3 km2 (2%) of its ice cover. Further 4.9 km2 disappeared (10% of the original ice cover, i.e. in 1956). The ice retreat magnitude in this period cannot be attributed to in-built variations of the glacier system. Further, it is associated to similar glaciers retractions and ice shelves collapses in the northern most part of the Antarctic Peninsula. Probably this general ice retreat results from or is enhanced by the atmospheric warming recorded for the region since 1940s.