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Dissertations |
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MARIANA ANDRIOTTI GAMA
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Petrographic and lithogeochemical characterization of metacarbonic and chalcysilicate succession of Jacuri Valley - BA: Paleoenvironmental conditions and phosphogenetic processes
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Advisor : AROLDO MISI
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COMMITTEE MEMBERS :
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AROLDO MISI
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ANGELA BEATRIZ DE MENEZES LEAL
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JULIANA CHARÃO MARQUES
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Data: Apr 4, 2019
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Show Abstract
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Based on the behavior and litogeochemical correlations, the marble and calcissilictic rocks of Vale do Jacurici, north-central of Bahia, demonstrated association with a paleoproterozoic shallow marine paleoenvironment, involving oxygen availability in the basin, conditions that favors carbonate precipitation and phosphate concentration. This supracrustal succession is the horst rock of the chromite mafic-ultramafic layered intrusion from Vale do Jacurici.These rocks are deformed, metassomatized and metamorphosed under high amphibolite to granulite conditions. Intrusive relations with the Itiúba Sienite and Mafic-ultramafic Complex Vale do Jacurici, mineralized in chromite, indicate the minimum Paleoproterozoic age for the succession. The core samples studied lithologies consist of lizardite marbles, lizardite-forsterite marbles, some of those are magnetite or garnet-bearingnd, lizardite-apatite marbles, lizardite-forsterite-biotite marbles, pure marbles, in addition to diopsidites, diopsidites apatite-bearing, biotite-hyperstenium diopside granulite and garnet-biotite-hypersenium-diopside granulite (calcissilictic granulites). Despite of the high metamorphic and deformational degree in which they are found, in marble, marine signatures preserved in RRE+Y patterns (PAAS normalized) and traces with negative Ce-anomalies and positive Y and Gd-anomalies, as well as Y/Ho ratios near to the values of sea water (60-168) are identified. Crustal contamination patterns indicate the presence of terrigenous components, especially in calcissilictic rocks, resulting in positive relations Zr versus Hf, general enrichment of ΣRRE+Y and Pr/Yb [SN], Y/Ho (< 30) and less marked anomalies, especially in calcissilictic rocks. The presence of variable magnitudes of positive Eu-anomalies may reflect the contribution of signatures from residual Archaean seas, as well as the influence of late magmatic fluids. Anomalous values of P2O5 in marbles and diopsidites (1.38%, 2.07%, 2.3% and 4.56%) were obtained at the boundary zones between terrestrial and marine contribution, delimited with Y/Ho reference values, evidencing stratigraphic control in phosphogenesis events. These evidences indicate a paleoenvironment involving conditions related to global climatic events that favors phosphate concentration, similar to Paleoproterozoic phosphate mineralized sedimentary basins in São Francisco Craton and other parts of the world.
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2
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MAÍRA SAMPAIO DA COSTA
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COMPARATIVE HYDROGEOCHEMICAL STUDY BETWEEN NEOPROTEROZOIC CARBONARY ROCK ENVIRONMENTS IN THE STATE OF BAHIA
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Advisor : SERGIO AUGUSTO DE MORAIS NASCIMENTO
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COMMITTEE MEMBERS :
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SERGIO AUGUSTO DE MORAIS NASCIMENTO
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MARIA DA CONCEICAO RABELO GOMES
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CÍCERO DA PAIXÃO PEREIRA
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Data: Apr 30, 2019
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Show Abstract
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The Neoproterozoic carbonate aquifers Salitre (Group Una), Sete Lagoas / Lagoa do Jacaré (Bambuí Group), Olhos d'água / Jacoca (Vaza-Barris / Miaba Group) of the State of Bahia, Brazil, are valuable groundwater reserves. These environments are areas of high economic interest for the purposes of human supply and also of agriculture and livestock due to the fertile soils, slightly uneven reliefs altitudes and reduced drainage surface. Due to this, the need for scientific research on the groundwater of these environments is validated. This study compares the hydrochemical characteristics of the karstic aquifers analyzed using basic and advanced statistical tools (analysis of variance, Tukey test, multiple regression and Spearman correlation), Qualigraf, Excel and PHREEQC software. For this, it was used hydrogeochemical data of tubular wells obtained from the groundwater information system of the Company of Research and Mineral Resources (CPRM), the SIAGAS. The results show differentiation between carbonate environments due to the concentration variation of Mg+ 2 and HCO3- elements. The Sete Lagoas / Lagoa do Jacaré Fm differ from the others due to mean of Ca+ 2 and differs from the Salitre Fm due to mean of SO4-2. Despite the specific chemical differences, the hydrogeochemical studies show that the Salitre Fm and the Sete Lagoas / Lagoa do Jacaré Fm have similar faciological characteristics, being classified mainly as bicarbonated calcium. These environments present a predominant influence of the chemical elements of lithological origin than aggregate rainfall components. The Olhos d'água / Jacoca Fm have different hydrophaciological characteristics being classified as mixed calcium and chlorinated chlorides. Due to the high content of Cl-, it is suggested a greater influence of the semi-arid climate than chemical elements of lithological origin.
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3
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REBECA DE JESUS BARBOSA
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ANÁLISE GEOMÉTRICA E CINEMÁTICA DE ESTRUTURAS NEOTECTÔNICAS DA FORMAÇÃO BARREIRAS NO LITORAL DOS ESTADOS DE PERNAMBUCO, PARAÍBA E RIO GRANDE DO NORTE
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Advisor : LUIZ CESAR CORREA GOMES
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COMMITTEE MEMBERS :
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LUIZ CESAR CORREA GOMES
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CARLOS CÉSAR UCHÔA DE LIMA
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IDNEY CAVALCANTI DA SILVA
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Data: May 3, 2019
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Show Abstract
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O Grupo Barreiras (GB) é uma cobertura sedimentar datada do Mioceno que ocorre sob forma de tabuleiros em boa parte da costa Brasileira. Sua deposição é contemporânea ao início das atividades Neotectônicas, e essa cronocorrelação é registrada no GB em termos de estratigrafia, faciologia e deformação. Na área de estudo, litoral entre os estados de Pernambuco, Paraíba e Rio Grande do Norte, o GB porta padrões de orientação estruturais observáveis em macroescala, considerando lineamentos geomorfológicos regionais, e observáveis em mesoescala, considerando falhas, fraturas e zonas de cisalhamento medidas em afloramentos. A partir do tratamento estatístico de lineamentos traçados em relevo sombreado e de estruturas medidas em campo, foi possível constatar que o GB apresenta três principais padrões de orientação de estruturas: NE-SW, herdado das estruturas dúcteis do embasamento cristalino (Província Borborema), N-S, relacionado à herança mesozoica de abertura do Atlântico Sul, e NW-SE, de provável origem Neotectônica.
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4
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FRANZ RANGEL DA SILVA
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Use of ecosystem services as strategy for coastal cities adaptation to climate change effects on river flood risk
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Advisor : JOSE MARIA LANDIM DOMINGUEZ
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COMMITTEE MEMBERS :
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JOSE MARIA LANDIM DOMINGUEZ
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YVONILDE DANTAS PINTO MEDEIROS
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LAFAYETTE DANTAS DA LUZ
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Data: May 7, 2019
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Show Abstract
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The coastal plains are flat relief landscapes, usually intersected by fluvial channels with flow influenced by the tidal regime. In these environments, the effects of climate change on extremes of precipitation and sea level, associated with the densification and expansion of urban occupancies along the low-elevation coastal zone (LECZ), will increase the frequency of natural disasters of hydrological origin, as well as the damage caused by river floods, requiring the adaptation of coastal cities. This article deals with the relevance of ecosystem services as a means of controlling river flood risks induced by the effects of climate change in coastal cities, adopting a multivariate approach that portrays the contribution of the hydrological and coastal processes involved. By comparing the risks of river flooding in different scenarios designed according to the climate trends and soil cover patterns of the Jaguaribe river basin and conjugated (JRBC), located in the city of Salvador, capital of the State of Bahia, Brazil, it was possible: (i) to deduce the impact of climate change on the hydrological and hydraulic behavior of natural floods in coastal areas; and (ii) to assess the impact of the loss of natural ecosystems on the risks of river flooding on an urbanized coastal plain. Throughout the 21st century, climate change could increase the risk of fluvial flooding in LECZ of JRBC by about 21% - growth of approximately R$ 910,000 in expected annual damage between 2010 and 2100 -, with intensification of precipitation extremes, the main factor responsible for this growth. By the end of the 21st century, the loss of natural ecosystems could mean increases in the risk of flooding corresponding to 31% (suppression of the Atlantic Forest) or 120% (removal of wetlands) from the increase due to climate change. The wetlands and downstream artificial ponds compensate the loss of some of the benefits provided by the Atlantic Forest, which reduces the impact of forest suppression on flood risks in LECZ. The increase in the damages caused by the suppression of the Atlantic Forest or wetlands will be more significant in the floods of greater frequency, a consequence of the hydrological sensitivity of the ecosystem services to the rainfall volumes produced by the extremes of precipitation. The use of ecosystem services is a strategy that assumes importance for the urban stormwater management in coastal cities, especially in the context of planning aimed at increasing urban resilience according to a holistic perspective of the impacts of climate change. However, ecosystem-based adaptation is not a "no regrets" strategy because its effectiveness in mitigating the risk of river flooding in coastal plains requires the compensation of the hydrological sensitivity of natural ecosystems through association with conventional engineering solutions, and the proper positioning of these ecosystems within the river basin.
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5
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DANIELLE SAMPAIO NASCIMENTO
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NEOTECTONIC ORTORHROMIC DEFORMATION STANDARD IN THE BARREIRAS NE DA BAHIA FORMATION, BRAZIL
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Advisor : LUIZ CESAR CORREA GOMES
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COMMITTEE MEMBERS :
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LUIZ CESAR CORREA GOMES
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CARLSON DE MATOS MAIA LEITE
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DILCE DE FÁTIMA ROSSETTI
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Data: May 28, 2019
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Show Abstract
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The Barreiras Formation is a terrigenous sedimentary cover that occurs almost continuously on the Brazilian coast and is distributed from the state of Amapá to Rio de Janeiro. The present work has the objective of identifying the main deformational structures present in the sediments of the Barreiras Formation on the northeast coast of Bahia. As a specific objective we have: i) to draw the structural lineaments in satellite image ii) to compare the field data with the data obtained in satellite image ii) to determine the structural inheritance of the basement iii) to integrate the data and to propose a neotectonic model . The research area is located on the northeast coast of the State of Bahia between the municipalities of Camaçari and the extreme south of the State of Sergipe. Because it is a densely populated area and home to several real estate projects, it is of fundamental importance to study the tectonic and deformation aspects of this unit. It is located in the context of the São Francisco Craton and includes part of the crystalline basement, Archaean / Paleoproterozoic Domain, represented by the northern segment of the Salvador Esplanada Boquim Orogen, the Recôncavo Basin and the Neogene / Quaternary Domain, represented by the Barreiras and Post-Barreiras Formation . The lineaments obtained in the basement have a preferred direction of N040 ° / 050 °, N60 ° / 070 °, 150 ° / 160 °, and the Paleozoic / Mesozoic Lineaments have the N040 ° / 050 °, N100 ° / 110 N110 ° / 120 °, and the Neogene Domain has standards ranging from N070 ° / 080 °, N100 ° / 110 ° and N030 ° / 040 °. The data obtained in the field of failure and fracture of the Fm. Barriers vary between N40 ° / 050 °, N060 ° / 070 ° compared to the structures of the other units, there was a repetition between the structures, which reinforces the idea of reactivation of preexisting faults and generation of new structures in the Fm. Barriers and measurements of the ductile and ductile / plastic field structures present Orthorhombic patterns typically neotectonic.
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6
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ANDRÉIA GONÇALVES DE ARAÚJO NUNES RANGEL
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Petrographic and litochemical study of the mafic and ultramafic body in Campo do Meio’s Farm, Marcionílio Souza – Bahia – Brazil
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Advisor : ANGELA BEATRIZ DE MENEZES LEAL
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COMMITTEE MEMBERS :
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ANGELA BEATRIZ DE MENEZES LEAL
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REINALDO SANTANA CORREIA DE BRITO
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MARIA ZÉLIA AGUIAR DE SOUZA
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Data: Jun 7, 2019
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Show Abstract
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The mafic-ultramafic body in Campo do Meio’s Farm, located in the city of Marcionílo Souza, state of Bahia, is characterized as an asymmetrical body with 1300x500m and eastwest orientation. It is inserted in the São Francisco Craton, more precisely in the Jequié Block, intruded among the chonockitic granulitic encasers. Lithographically, the body shows inverted stratigraphy, being composed of peridotites (dunite, harzburgite and lherzolite) pyroxenites (olivine-ortopyroxenite, olivine websterite, websterite, pyroxenite hornblende and pyroxene hornblendite) and hornblende gabronorite as mafic representative. Ultramafic rocks present varying degrees of serpentination, as well as post-magmatic processes of chloritization and thallification. However, the primary textures were not completely obliterated, thus preserving the igneous nature of the body, exhibiting primary paragenesis represented by forsterite / chrysolite, spinel (hercinite / magnetite), enstatite, augite and magnesium-hbl. In mafic rock, the deformation was more expressive with paragenesis formed by magnesium-hbl, diopside and labradorite. The binary diagrams of larger elements, trace elements and rare earths show that in spite of the post-magmatic events that affected the rocks, there was no significant interference in the original rocks, where they present olivine and orthopyroxene as the main controlling phases fractionation of ultramafic rocks. From the lithochemical data, the body is characterized with an intrusion of continental toleitic nature and affinities with komatiitic magmas. In geotermobarometric data it is verified that the crystallization temperature of the body was 1325 to 1704ºC and metamorphic rebalancing temperatures were 869ºC with pressure around 4 to 4.5 kbar, compatible with the pressure data for the granulitic nesting rocks. The data of this article will be published in the Journal of Research in Geosciences (UFRGS), as a basic requirement for the master's degree in the Graduate Program of the Federal University of Bahia (UFBA).
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7
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ADRIANE GONÇALVES DE ARAUJO NUNES RANGEL
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ANTECEDENT TOPOGRAPHY CONTROLS PRESERVATION OF LATE QUATERNARY TRANSGRESSION RECORD AND CLINOFORM GEOMETRY: THE SÃO FRANCISCO DELTA (EAST-NORTHEASTERN BRAZIL)
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Advisor : JOSE MARIA LANDIM DOMINGUEZ
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COMMITTEE MEMBERS :
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JOSE MARIA LANDIM DOMINGUEZ
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JUNIA KACENELENBOGEN GUIMARAES
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HORTENCIA MARIA BARBOZA DE ASSIS
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Data: Jun 10, 2019
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Show Abstract
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The present study used shallow high-resolution seismic surveys to characterize the architecture and stratigraphic evolution of the last depositional sequence of the São Francisco Delta (SFDS), deposited during the late Pleistocene/Holocene. The SFDS accumulated in a bathymetric depression of the continental shelf associated with the São Francisco canyon head. The existence of this depression resulted in additional accommodation space measuring several tens of meters, which allowed the accumulation of a continuous stratigraphic record of eustatic sea-level rise since the Last Glacial Maximum on one of the shallowest and narrowest continental shelves in the world. Six major seismostratigraphic units were individualized. The lower units (Su1, Su2 and Su3) accumulated around the head of the canyon, limited by the walls of the bathymetric depression. Su1 was possibly drowned by MWP1A. Units Su2 and Su3 accumulated over the ensuing period of reduced rates of eustatic sea-level rise between the end of MWP1A and the Younger Dryas (YD). The top of Su3 transitions laterally to a wave-cut terrace engraved in the walls of the bathymetric depression. This terrace is located between 55 and 60 m below present sea level, and probably marks shoreline position during the YD. Su3 was drowned by MWP1B, as indicated by sediment wedges (Su6) that buried the top of this unit in the lateral portions of the bathymetric depression. Su4 was deposited still within a coastal embayment, during a period of low sea-level rise rates after MWP1B. Su4 was apparently drowned by MWP1C around 8.4 ka BP, marking the formation of the maximum flooding surface. The deposit of Su5, which corresponds to the most recent unit of the delta, only took place after the stabilization of eustatic sea level that began in 8-7.5 ka BP. This study demonstrated how variations in eustatic sea-level rise rates combined with antecedent local morphology favored the creation of a continuous sedimentary record of Holocene transgression.
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8
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NAIR LORENA GASPAR NONATO DA SILVA
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Sismoestratigrafia Correlativa entre as Bacias de Tucano Sul e Recôncavo
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Advisor : MICHAEL HOLZ
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COMMITTEE MEMBERS :
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JOELSON DA CONCEICAO BATISTA
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MICHAEL HOLZ
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SUZAN SOUSA DE VASCONCELOS
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Data: Jun 18, 2019
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Show Abstract
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The sequence stratigraphy applied to rifte basins consists of an adaptation of the classic model that is in full consolidation phase. The guiding principles of sequence stratigraphy are applied in any sedimentation context. They are fundamental to understanding the depositional history of a basin. The present work had as objective to study the seismic stratigraphy framework of Tucano Sul basin under the bias of sequence stratigraphy applied to rifte basins in order to correlate this study with the Recôncavo basin. From the integration of the seismic sections associated to the data of 15 wells (geophysical and lithological profiles) the data were processed in the IHS Kindle seismic interpretation software. The seismic stratigraphic analysis involved the interpretation of reflector terminations, definition of the seismostratigraphic units from the mapping of key surfaces as well as the characterization of the major seismic facies. As a result, five seismostratigraphic units were identified according to the model adopted here: Pre-rift unit, Rifte 1, Rifte 2, Rifte 3 and Post-rift unit. Five seismic facies were defined, SF1 to SF5, each with its characteristic parameters. At the end, a discussion was proposed about the seismostratigraphic correlation with the Recôncavo basin. For the rifte interval, Tucano Sul presented a seismostratigraphic sequence less than the Recôncavo basin, indicating an important erosive event during its development.
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9
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BRENDA LORENA SOARES DA SILVA BRAGA
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δ13C OF SCLERACTINIAN CORALS A 12CO2 QUANTIFICATION TOOL ABSORBED BY THE SOUTHERN ATLANTIC SURFACE OCEAN
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Advisor : RUY KENJI PAPA DE KIKUCHI
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COMMITTEE MEMBERS :
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RUY KENJI PAPA DE KIKUCHI
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MARIA DO ROSARIO ZUCCHI
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BÁRBARA PINHEIRO RAMOS
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Data: Jul 19, 2019
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Show Abstract
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The growing interest in palaeoclimatic reconstructions has promoted a quick advancement in studies that use geochemical records from natural archives (e.g. tree rings, ice cores, corals) to access past environmental conditions. Among these, the coral-based records stand out as an important tool in understanding climate variability in the tropics. During the precipitation of the exoskeleton of corals from sea water, isotope ratios and trace elements (e.g. δ18O, δ13C and Sr/Ca) are incorporated in this structure. The isotopic composition of coral skeleton (δ18O and δ13C) have often been used as an indicator in the estimate of various environmental factors (e.g. temperature, solar radiation, cloud cover, turbidity, dissolved inorganic carbon). The oxygen isotope has been used in the reconstruction of past temperature and carbon isotope has been used to estimate changes in the isotopic composition of dissolved inorganic carbon in the oceans because of changes in δ13C-CID related to increase of 12C derived from burning of fossil fuels known as the Suess Effect. Here we report the δ18O and δ13C isotopic data based in colonies of the species Mussismilia braziliensis and Siderastrea stellata, to the South Atlantic Ocean. Isotope cycles indicate ages of 15, 23 and 27 for colonies of M. braziliensis and 22, 32 and 41 for colonies of S. stellata. The average values of carbon and oxygen isotope were respectively of 0.13 ± 0.99 and 2,19 ± 0.23‰ (SS01G),-1,69 ± 0.55 e-2,39 ± 0.98‰ (SS02D), 0.22 ± 0.46‰ e-2,24 ± 0.33‰ (SS03D) and -0.71 ± 0.74 and-3 ± 1.21‰ (MB01_2C),-0.58 ± 3,09 e-2,67 ± 0.08‰ (MB02D),-1.44 ± 0.11 and-2.70 ± 1.28‰ (MB03B). Data from the SOI (Southern Oscillation Index) were used and compared with the oxygen isotope records. The species S. stellata exhibited a negative trend in the δ13C temporal series of the three colonies, similar to the impoverishment observed in other regions of the South Atlantic. The δ13C of the colonies of M. braziliensis presented short-term variation mainly related to physiology. Isotopic carbon record based on corals of the species S. stellata is an important tool to tell how the isotope change that has been occurring in CO2 from the Equatorial South Atlantic Ocean. The isotopic content of the species M. braziliensis needs to be better explored.
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10
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RODRIGO AMARAL LANFRANCHI
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Aplicação do Sensoriamento Remoto e Espectroscopia de Refletância para a Exploração de Minério de Ferro no Setor Intracontinental do Orógeno Araçuaí-Oeste Congo
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Advisor : SIMONE CERQUEIRA PEREIRA CRUZ
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COMMITTEE MEMBERS :
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ADALENE MOREIRA SILVA
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SIMONE CERQUEIRA PEREIRA CRUZ
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TATI DE ALMEIDA
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Data: Aug 14, 2019
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Show Abstract
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This study proposes to use spectral analysis techniques (Mixture Tuned Matched Filtering - MTMF and Spectral Angle Maper - SAM) using images from the Sentinel-2 sensor to guide the discrimination and delimitation of iron rich sites in the intracontinental sector of the Araçuaí Orogen -Owest Congo. This sector comprises the folding and riding belts of the Serra do Espinhaço do Norte and Chapada Diamantina, both developed at Ediacarano. For this work two iron ore (hematite and goethite) extraction areas were selected in Caetité and Piatã, located respectively in these belts, in the state of Bahia. At these sites, rock samples were collected for petrographic, geochemical and spectorradiometric analyzes to guide the search for other targets for iron ore prospecting in the region.
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11
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ERICK MATHEUS VAZ GUEDES
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P-T PSEUDOSECTIONS BASED ON THE CHEMICAL VARIATION OF ZONED GARNETS IN THE METAPELITIC ROCKS OF EAST MACURURÉ DOMAIN, SERGIPAN OROGEN
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Advisor : JAILMA SANTOS DE SOUZA DE OLIVEIRA
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COMMITTEE MEMBERS :
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JAILMA SANTOS DE SOUZA DE OLIVEIRA
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ANGELA BEATRIZ DE MENEZES LEAL
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IVANA CONCEICAO DE ARAUJO PINHO
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Data: Aug 29, 2019
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Show Abstract
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Macururé Domain corresponds to the most expressive domain of Sergipan Orogen, emerging in the states of Bahia, Sergipe and Alagoas and is composed predominantly by metapsamopelites. This work aimed to identify the pressure and temperature conditions that these rocks were submitted to, with P-T pseudosection building by Perple_X software. Recent works have shown that the metapelitic rocks of the Macururé Domain exhibit a metamorphic progression from south to north from the schist-green to amphibolite facies, marked by the metamorphic zoneography initiated by the garnet zone, passing through the kyanite zone and ending up in the silimanite zone, showing an intermediate pressures metamorphism (Barrowian). The results obtained by bulk-rock composition + the variation of XCa and XMg core-edge garnet crystals (XRF and EMP-WDS), for a sample from each zone indicated conditions that confirmed this progression of metamorphism to northern, however, an event which stabilized the three samples under amphibolite facies conditions was recorded. For the sample placed on garnet zone, the conditions indicated by the garnet core and edge were 449ºC - 0.438GPa and 629ºC - 1.094GPa, respectively. While for the sample placed on kyanite zone the values obtained were 515ºC - 0.655GPa (core) and 616ºC - 0.845GPa (edge) and for the sample situated on silimanite zone the presented were 512ºC - 0.615 GPa (core) and 617ºC - 1,129GPa (edge).
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12
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ROBSON MAURO DOS ANJOS
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The alkaline rocks of the Jaguaquara region – petrography and litogeochemistry, Jequié block - Bahia, Brazil
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Advisor : JAILMA SANTOS DE SOUZA DE OLIVEIRA
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COMMITTEE MEMBERS :
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JAILMA SANTOS DE SOUZA DE OLIVEIRA
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JOHILDO SALOMAO FIGUEIREDO BARBOSA
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ERON PIRES MACEDO
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Data: Sep 5, 2019
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Show Abstract
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The geological evolution of the São Francisco Craton (CSF), in the State of Bahia, is evidenced by Archean and Paleoproterozoic lands, by metasedimentary and sedimentary coverings, besides the mafic magmatism whose origin corresponds to the Meso-Neoproterozoic. In Bahia, the CSF was structured by the amalgamation of four Archean crustal segments: the Gavião Block (BG), the Serrinha Block (BS), the Jequié Block (BJ) and the Itabuna-Salvador-Curaçá Block (BISC). In this context, the rare records of occurrences of alkaline magmatism in the State of Bahia date from the Archean to the Neoproterozoic. In the Jaguaquara region, the focus of this study, these rocks comprise one of the alkaline igneous occurrences in the Center-South portion of the State of Bahia, inserted in rocks of the Jequié Complex located in the homonymous block, close to the transition with the Itabuna-Salvador-Curaçá Belt.. The objective of this study is to proceed to the geological mapping of the anomalous magnetic zone, which at first is related to the existence of the alkaline rocks of the Jaguaquara region and their granulitic nesting. Thus, the fieldwork aided by petrography allowed the individualization of two sets of lithophages, the first alkaline composed by: Metasienite, Albitated Metasienite, Quartz-Syenite, Albitrated Quartz-Syenite and Albitite, and the second comprising the enclosing rocks, in its granulitic essence divided into: Kinzigitos, Grunerita-Gondito, Bandada Ferrous Formation, Tremolithito, all of origin of dererivatives and the Enderbites, Charnoenderitus and Charnockitos of orthoderivative origin. Based on lithogeochemistry, alkaline lithofacies are classified as quartz monozonite syenites, predominantly peralcaline. The parallelism observed between the ETR and multi-element lithofacies spectra indicates that the alkaline rocks are cogenetic and possibly reflect the geochemical signature of the magma generating source. Tectonic classification diagrams for the alkaline rocks of Jaguaquara suggest that the lithotypes are late post-orogenic. Finally, the lithogeochemistry allowed a better understanding of the geological processes acting in both the alkaline lithotypes and the embedded rock protoliths, being important for the understanding of the role of tectonics and metamorphism of the study area.
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13
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AMANDA DE MACEDO PEIXOTO
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HYDROGEOCHEMISTRY OF THE FISSURAL AQUIFER OF CONCEÇÃO DE CONITÉ MUNICIPALITY, BAHIA, BRAZIL
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Advisor : MANOEL JERONIMO MOREIRA CRUZ
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COMMITTEE MEMBERS :
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MANOEL JERONIMO MOREIRA CRUZ
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SERGIO AUGUSTO DE MORAIS NASCIMENTO
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OLGA MARIA FRAGUEIRO OTERO
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Data: Dec 19, 2019
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Show Abstract
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The municipality of Conceição do Coité, Bahia, is characterized by low rainfall and high evapotranspiration rates, so groundwater becomes an important option for the development of anthropic activities, which allow domestic exploitation, irrigation, among others. This work aims to characterize the groundwater hydrogeochemistry of Conceição do Coité, identifying the main chemical constituents present to evaluate their suitability for human use. Analytical data from 58 tubular wells archived in the CERB database in 2006 were processed and added to those obtained in this research in 2018. The data were used to characterize the quality of these waters for irrigation purposes and for an analysis of chemical and temporal evolution of 12 years. For the classification of the water type, the Piper triangular diagram was used, where the obtained chemical relations allowed to classify the waters as sodium chloride. In the evaluation of this resource for human consumption, it is concluded that they are improper for potability, however, for this confirmation, bacteriological analyzes are necessary. For irrigation water diagnosis, the SAR (Sodium Adsorption Ratio) diagram and Ayers & Westcot classification were used. For the spatialization of the results, thematic maps of the variables were made, using krigeagem as an interpolator to indicate areas that have groundwater that can be used. It was concluded that high salt concentrations may cause salinization and sodification of the soil and consequently deterioration of some crops. Comparing the analyzed parameters with the irrigation use patterns, it was observed precariousness that make their use in more than 70% of the analyzed wells unfeasible.
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Thesis |
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1
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CARLA ISOBEL ELLIFF
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PROTEÇÃO À LINHA DE COSTA POR RECIFES DE CORAL DO ARQUIPÉLAGO DE TINHARÉ-BOIPEBA, BAIXO SUL DA BAHIA, FRENTE A MUDANÇAS CLIMÁTICAS
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Advisor : IRACEMA REIMAO SILVA
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COMMITTEE MEMBERS :
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IRACEMA REIMAO SILVA
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JANINI PEREIRA
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JOSE RODRIGUES SOUZA FILHO
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JUNIA KACENELENBOGEN GUIMARAES
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RICARDO PIAZZA MEIRELES
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Data: Feb 5, 2019
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Show Abstract
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Shoreline protection is one of the most relevant ecosystem services delivered by coral reefs. However, knowledge on this process is still quite fragmented in current literature, with important gaps regarding how this service is delivered by these ecosystems in the face of climate change scenarios. The overall objective of the present project was to generate scenarios of changes to shoreline protection by coral reefs in the Archipelago of Tinharé-Boipeba, BA, based on sea-level rise projection due to climate change. Coastal dynamics modelling was conducted using the set of computational tools within the coastal modelling system SMC-Brasil. Fringing coral reefs showed high efficiency in attenuating wave energy even under energetic conditions during high tides in the current scenario. SMC-Brasil was also used to model sea-level rise scenarios for the horizon years of 2070 and 2100. The values found were 6 mm/year in the conservative scenario and 8 mm/year in the pessimistic scenario. These sea-level rise rates were used in the coastal erosion and flooding vulnerability model from the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) software in scenarios with and without coral reefs, so to qualitatively evaluate the contribution of this ecosystem. The archipelago was classified as intermediately vulnerable currently, with several socioeconomically important areas becoming highly vulnerable if coral reefs are unable to deliver shoreline protection. Coastal management strategies should seek to increase coral reef resilience by reducing local impacts. Moreover, environmental and socioeconomic data should be more available to allow evidence-based decision-making. Finally, international coral reef monitoring protocols should include geomorphological information in addition to biological data
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2
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MARIA DO CARMO FILARDI BARBOSA
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Geoenvironmental Influences on the different phytophysiognomis in the sites of the Dunes Park, Salvador-Bahia/Brazil
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Advisor : MANOEL JERONIMO MOREIRA CRUZ
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COMMITTEE MEMBERS :
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MANOEL JERONIMO MOREIRA CRUZ
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BARBARA ROSEMAR N DE ARAUJO
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MARIA ELOISA CARDOSO DA ROSA
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ALISSON DUARTE DINIZ
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MANUEL VITOR PORTUGAL GONÇALVES
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Data: Feb 22, 2019
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Show Abstract
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The vegetation of the Park of Dunes, Salvador - Bahia, presents diversified flora belonging to the different topographical zones and where exists an intercommunication of the distinct biological and geologic characteristics. This paper had as objective main to understand as the topographical and edaphics factors could influence in the flora diversity, the distribution of the vegetal formations and in the focal plants, of the dune system to dune ofon the restinga ecosystem of restinga of the Park of Dunes. In order to do that, one transect was drawn perpendicularly to the beach line. In each transect was implanted (08) eight plots of 25x25m distant from each other 100m, totalizing 900m. For the botanical material, the collection was made within the parcels. In relation to the geological material, In each plot was opened a trench of 1m wide 60cm of depth and where the sediments were collected. The results show that the families Fabaceae, Myrtaceae Rubiaceae and Orchidaceae had been most representative. Being the Fabaceae family with a bigger amount of species in all the study plots. They had been evidenced that, in the plots of lower altimetry, lower average levels of finer sand fraction had occurred, lower contents of nutrients as exchangeable calcium, bioaviable phosphorus and lower vegetal densities with focal species when compared with the plots of bigger altimetrias. Moreover, in these lowered areas more suitable species to the periodic overflows had been evidenced. It was also evidenced that pH was presented very acid, with percentage of saturation of aluminum high, which allowed an increase of exchangeable aluminum in the solution of the soil which provided in the majority of the plots less availability of nutrients. Therefore, the different topographies had determined the draining capacity as well as the physical and chemical properties of the sediments that compose sandy lands of the Park of Dunes. These conditions contributed to influence the diversity and the standart of distribution of the plant formations. Therefore, the presented results, in this pape, confirm that the topographical conditions and the edáficos parameters chosen for this study served as a filter to select the capable species of if establishing and persisting on determined specific habitats.
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3
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CAMILA FIGUEREDO OLIVEIRA
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DIGITAL CLOUD PROCESSING FOR SPECTRAL AND GEOPHYSICAL CHARACTERIZATION OF NEOPROTEROZOIC LITHOFACES FROM THE IRECÊ SUB-BASIN, BAHIA.
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Advisor : AROLDO MISI
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COMMITTEE MEMBERS :
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AROLDO MISI
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ANA VIRGINIA ALVES DE SANTANA
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ARDEMIRO DE BARROS SILVA
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RODRIGO NOGUEIRA DE VASCONCELOS
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TATI ALMEIDA
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Data: Mar 25, 2019
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Show Abstract
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The Irecê Sub-Basin is formed by carbonate and siliciclastic Neoproterozoic sequences deposited in marine environment and mapped as Salitre Formation (Una Group, São Francisco Supergroup). Among the various mineral occurrences found in this basin are the deposits of phosphate and zinc-lead sulfide. The use of cartographic products obtained by integrating spectral and aerogeophysical (gamma spectrometric) data for the discrimination of geological units has shown good results. Some studies show that both reflectance spectroscopy and multispectral and hyperspectral remote sensing images are efficient for the qualitative and semi-quantitative distinction of the spectral reflectance of the various geological materials and that gamma-spectrometric data indicate geophysical patterns associated to lithostratigraphic units. The aim of this thesis was to characterize the spatial distribution of the lithostratigraphic units in the Irecê sub-basin by associating Remote Sensing data (Landsat and Sentinel images) and Geophysical data (40K, 238U and 232Th counts images). In the map of gammaspectrometric variables it was observed that a important part of the studied area is characterized by intermediate values for the three elements, expected behavior in sedimentary rocks due to grain size and ease of weathering and leaching processes. The ternary map compared to the geological map, showed a strong correlation in the separation of the units. The Landsat - 8 and Sentinel - 2A images, acquired on the Google Earth Engine platform, in which all data processing was developed, were used for the spectral analyses. The signatures obtained by spectral indexes, have their contours similar to some geological units mapped by reference maps. The Sentinel - 2a images presented more detailed data of the lithofacies by possessing spatial and spectral with higher resolutions than the data of the series Landsat - 8, in the near infrared visible. The integration of geophysical and remote sensing data was performed by the Random Forest classifier, which identified clusters of spectral and geophysical variables associated with the main lithologic types of the sub-basin. For the homogenization of classes in the images, the Majority filter was used, which allowed to unify distortion pixels, reducing the noise and raising the visual quality of the maps. Statistical criteria were used to evaluate and compare the accuracy of the classification map, which showed that the commission error moderate for most units, with values between 30% and 39%. Already the error of omission of the classes Pecb1, Quartz Shaft, QC, Un B1 was superior to 70%. At the end of the search for the most appropriate model based on the data, a statistically correct rate was obtained, ranging from 69% to 71%. The results of the two types of accuracy were concordant, indicating that the classifications are considered very good. However, the classification using Sentinel - 2A images presented a slightly better result when compared with the Landsat - 8 image. The study demonstrated satisfactory results for the integration of satellite images and geophysical data using the Random Forest classifier in the Google Earth Engine platform and a litho-spectral and geophysical model was proposed for the Irecê Sub-basin. Although our study focuses on this sub-basin, the developed methodology can be applied in other regions of similar geological environment.
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4
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NARAYANA FLORA COSTA ESCOBAR
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Origin of organic matter in the deltaic clinoform of the river São Francisco and the impact of the large dams
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Advisor : JOSE MARIA LANDIM DOMINGUEZ
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COMMITTEE MEMBERS :
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JOSE MARIA LANDIM DOMINGUEZ
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OLIVIA MARIA CORDEIRO DE OLIVEIRA
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MANOEL JERONIMO MOREIRA CRUZ
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JUNIA KACENELENBOGEN GUIMARAES
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ICARO THIAGO ANDRADE MOREIRA
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Data: May 13, 2019
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Show Abstract
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The São Francisco river is one of the most important rivers in Brazil. The wave-dominated delta at its mouth includes a well-developed muddy clinoform on the adjacent shelf. This study aimed to understand sedimentary organic matter (OM) distribution and the relative contribution of terrestrial/fluvial and marine sources. A dense and evenly distributed sampling grid was used to evaluate the contribution of different OM sources and the influence of local factors. The following parameters were evaluated: grain size, total organic carbon (TOC), total nitrogen (TN), carbonates, and carbon isotopes (δ13C). The spatial distribution of OM properties showed very good correlation with the various sedimentary provinces of the clinoform (topset, foreset and bottom set) and the lateral contributions of sediments from neighboring reef bottoms, advected by coastal flows. TOC and TN varied respectively between 0.11 % and 1.56 % and between 0.02 % and 0.20 %. The distribution of these parameters in combination with %CaCO3 shows that the major contributors of TOC to the study area are the São Francisco river, coastal reefs located northwards, and shelf reef bottoms located northeastwards and southwestwards from the deltaic clinoform. The best indicator of river influence was provided by δ13C, with values ranging between -23 ‰ and -19 ‰. The spatial distribution of δ13C precisely mimics the various sedimentary elements of the clinoform, reflecting the pattern of river plume expansion observed during the last decades, which is characterized by low discharges, compared to historical values. Many studies in the literature, even using more sophisticated techniques, have frequently focused on sampling strategies using onshore-offshore transects without seeking integration with other local geologic and dynamic factors acting on a given study area. Here we have demonstrated the importance of reference studies, based on a dense and evenly spaced sampling grid and its integration with local geological, geomorphological and geophysical data to better understand the sources and origin of organic matter and its spatial distribution in deltaic settings. The São Francisco river is extremely important from a cultural, economic and energy generation perspective for the poorer northeastern portion of Brazil, and one of the most important and threatened rivers in the country because of human uses and climate changes.
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5
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JOANE ALMEIDA DA CONCEIÇÃO
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LEUCOGRANITIC MAGMATISM OF MACURURÉ DOMAIN, SERGIPANO OROGENIC SYSTEM, BORBOREMA PROVINCE, NE BRAZIL.
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Advisor : HERBET CONCEICAO
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COMMITTEE MEMBERS :
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HERBET CONCEICAO
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SIMONE CERQUEIRA PEREIRA CRUZ
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MOACYR MOURA MARINHO
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IGNEZ DE PINHO GUIMARÃES
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CARLOS DINGES MARQUES DE SÁ
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Data: May 24, 2019
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Show Abstract
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Leucogranites and S-type granites are magmas formed by the melting of metasediments and are closely associated with the continent-to-continent collision. In the Macururé Domain, located in the Sergipano Orogenic System, in the south of the Borborema Province, several leucogranite intrusions occur. The Glória Sul Stock is the most representative intrusion of this type of magmatism and consists essentially of biotite granites, granites with biotite and muscovite, muscovite granites. In the first two types of granites, there are microgranular syenitic enclaves. The geochemistry of these granites indicates that they were formed by fusion of igneous rocks. . However, the geochemical evolution in the Glória Sul Stock indicates that its rocks were formed from the mixture of shoshonitic mafic magma, represented by the microgranular syenitic enclaves, with felsic magma, probably from a crustal source. The comparison between the geological, petrographic and geochemical data available for the leucogranite intrusions of the Macururé Domain revealed that there are two sets of bodies based on age and texture. The oldest leucogranites, with ages of crystallization varying from 613-635 Ma, as is the case of Glória Sul Stock, does not exhibit deformation and is the most abundant group. Younger leucogranites, with crystallization ages ranging from 571-590 Ma, correspond to gneisses and are located in the eastern part of the Macururé Domain. Regardless of age, leucogranites have similar geochemical compositions and correspond to strongly evolved (> 70% SiO2) rocks, peraluminous, magnesian, with a calcium-alkaline geochemical signature. These same geochemical data suggest that these leucogranites were formed by magmas with close compositions, from the fusion of igneous protoliths in a collision environment.
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6
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RENILDA FÁTIMA GONÇALVES DE LIMA
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Hydrogeology and Vulnerability of the Salitre Karstic Aquifer, in the Una-Utinga Basin, Bahia
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Advisor : LUIZ ROGERIO BASTOS LEAL
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COMMITTEE MEMBERS :
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LUIZ ROGERIO BASTOS LEAL
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SERGIO AUGUSTO DE MORAIS NASCIMENTO
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CRISTOVALDO BISPO DOS SANTOS
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MARIA DA CONCEICAO RABELO GOMES
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MARIA DO ROSARIO ZUCCHI
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Data: Jul 26, 2019
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Show Abstract
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The Una-Utinga Basin (UUB), located in the central region of the Bahia state, houses an important karstic aquifer system, corresponding to the Saltpeter Formation, which carbonate rocks date from the Neoproterozoic and are divided into Gabriel/Nova América Unit and Nova América sub-unit Lapão. This work aims to present a hydrogeological characterization pioneer for the area, with a view to the hydrochemical, isotopic, of transmissivity and vulnerability issues of the Salitre aquifer in the UUB. For the hydrochemical, it was used chemical data from 35 tubular wells, collected in the area, analyzed in LEPETRO/UFBA, and 17 samples from the CERB database. The isotopic analysis was done from samples collected in 36 wells and performed in the Laboratory of Nuclear Physics/UFBA. The transmissivity was calculated by the analytical method of Theis and empirically recalculated by statistical analysis. For a better response of vulnerability mapping, it was necessary to obtain a surface karsification index previously, made from the mapping of dolines density and structural lineaments. Finally, the vulnerability was evaluated through the methods COP and PI, in order to make a comparison of their applications in the UUB. As results, 58% of bicarbonated water, 23% chlorinated, 13% mixed and 6% sulfated were obtained as water typology, Regarding potability, the analyzed parameter was salinity and 48% of the waters from the sweet wells, 33% brackish and 19% salted were obtained. In relation to the isotopes, the samples were divided into two groups of distinct signatures, when compared δ18O and STD mg/L. For transmissivity, the response was given as a potentiometric map of the UUB, which general flow of the waters of the Salitre aquifer tends to the west. The karst index generated a predictive map of features of the exocarste and divided the area into karsification classes. The areas with a high rate of karsification were called karst islands and were used differently in the assessment of vulnerability. These islands, for the most part, are conditioned to the occurrence of the Nova América sub-unit Lapão. The vulnerability assessment using the COP method presented 5 classes of vulnerability, while the PI 4. The greater area coverage in both methods corresponds to the low vulnerability class. The lithology and surface karstic features were shown to be more influential factors in the determination of vulnerability in both methods. In view of this range of analyzes it was concluded that (i) the typologies, ionic ratios and potability tend to follow the regional underground flow in the UUB; (ii) the transmissivity spatial model shows the area of greatest potential in the western portion of the UUB; (iii) the application of the karstic index revealed excellent acuity in the expression of the surface features of the karst system; (iv) the COP vulnerability method presented a more compatible response with the characteristics available to the UUB; (v) the combined analysis of the hydrogeological parameters and vulnerability demonstrated the compatibility among the karst islands (high vulnerability) and the greater spatial potentiality of the aquifer. Thus, it is necessary to pay greater attention to these areas in view of the high susceptibility to contamination of the Salitre aquifer. This research will fill a gap in the hydrogeological knowledge of karstic domains and their environmental management in the state of Bahia.
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7
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RICARDO RAMOS SPREAFICO
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GEOLOGY, PETROLOGY AND GEOCHRONOLOGY OF THE MUNDO NOVO GREENSTONE BELT AND OF THE Zn and Pb FAZENDA COQUEIRO DEPOSIT, SÃO FRANCISCO CRATON, NE BRAZIL
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Advisor : JOHILDO SALOMAO FIGUEIREDO BARBOSA
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COMMITTEE MEMBERS :
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ANGELA BEATRIZ DE MENEZES LEAL
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CARLSON DE MATOS MAIA LEITE
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ELTON LUIZ DANTAS
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JOHILDO SALOMAO FIGUEIREDO BARBOSA
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SIMONE CERQUEIRA PEREIRA CRUZ
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Data: Sep 13, 2019
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Show Abstract
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Field, petrographic, lithogeochemical, LA-ICP-MS U-Pb zircon geochronology, and Nd and Sr isotopic data were used to determine the geologic evolution, timing of volcanism and tectonic setting of the Mundo Novo greenstone belt (MNGB) including nearby units, such as the basement and younger granitic rocks in the eastern São Francisco Craton (NE Brazil). TIMS Pb-Pb geochronologic data allow determination of the timing and genesis of the Fazenda Coqueiro volcanogenic massive sulfide Zn-Pb deposit (FC) hosted in the MNGB. The basement of the greenstone belt (Gavião Block) comprises tonalite-trondhjemite-granodiorite orthogneisses, migmatites and subordinate metarhyolites and metagranites. The MNGB is divided into three lithological sequences: (i) the lowermost unit (metakomatiites); (ii) the middle unit (metabasalts, metadacites and metasedimentary chemical rocks); and (iii) the uppermost unit (metasedimentary siliciclastic rocks). Additionally, two Rhyacian-Orosirian granitic plutons occur in the area, the Areia Branca and Jequitibá metagranites. The metabasalt hosts two hydrothermal alteration zones in the FC: one carbonate, hosting massive sulfides composed mainly of sphalerite and galena; and the other argillic/chloritic, hosting mainly disseminated chalcopyrite. U-Pb zircon data from the Miguel Calmon and Fazenda Coqueiro metagranites in the Gavião Block yield crystallization ages of 3355 ± 16 Ma and 3227 ± 23 Ma, respectively, and both metagranites were derived from the lower continental crust based on low 87Sr/86Sri values (0.699 and 0.705, respectively) and negative values of ƐNd(t) (-3.7 and -3.6, respectively). The 2595 ± 21 Ma U-Pb zircon crystallization age of the metadacites allowed the determination of the timing of ocean floor volcanism in the middle sequence of the MNGB. The 2106 ± 71 Ma and 1975 ± 36 Ma U-Pb zircon crystallization ages for the Areia Branca and Jequitibá metagranites, respectively, which are both interpreted as derived from crustal protoliths based on high 87Sr/86Sri values (0.744 and 0.730, respectively) and negative values of ƐNd(t) (-7.7 and -6.5, respectively), record a Rhyacian-Orosirian tectonothermal event that affected the MNGB and the adjoining region. Pb-Pb sulfide data from the massive and disseminated zones in the FC yield a model age of approximately 2794 Ma sourced from the upper crust. The Pb-Pb crystallization age of 2747 ± 16 Ma was obtained from sphalerite and chalcopyrite samples from the massive and disseminated zones. Therefore, the following five stages are proposed for the tectonic evolution of the study region: stages (i) and (ii) were characterized by the establishment of the TTG basement by 3.35 Ga, when the Miguel Calmon granite was consolidated, followed by a rifting that formed the rhyolites, and subsequent granite formations occurred at 3.22 Ga (Fazenda Coqueiro granite formation), followed by the abort of the rift and a closure event. The volcanism during stage (iii) between 2.74 Ga and 2.59 Ga in the MNGB occurred in the oceanic crust between Archean cratonic blocks and related to FC genesis, and stages (iv) and (v) between 2.10 Ga and 1.97 Ga (granite formations) represent two stages of a progressive collision event in which the oceanic crust was compressed between the tectonic blocks from the eastern São Francisco Craton.
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8
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LUCAS TEIXEIRA DE SOUZA
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TECTONIC AND GEOCHRONOLOGY (U-PB) OF THE SUTURE ZONE BETWEEN ITABUNA-SALVADOR-CURAÇÁ AND JEQUIE BLOCKS, BAHIA, BRAZIL
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Advisor : LUIZ CESAR CORREA GOMES
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COMMITTEE MEMBERS :
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LUIZ CESAR CORREA GOMES
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NATALI DA SILVA BARBOSA
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ANGELA BEATRIZ DE MENEZES LEAL
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RITA CUNHA LEAL MENEZES DE OLIVEIRA
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ERON PIRES MACEDO
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Data: Dec 13, 2019
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Show Abstract
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The study area of this research is located in the central portion of the largest tectonic feature of the state of Bahia, the São Francisco Craton (SFC). More specifically on the boundaries between two of the main blocks that make up the craton, the Jequié, and Itabuna-Salvador-Curaçá blocks. The research mainly aimed at the reevaluation of the boundary between these blocks, using airborne geophysical maps and geological, structural, petrographic, geochemical and U-Pb geochronology data of rocks that occur in this region, to contribute to the knowledge of the geotectonic evolution that shaped the rocks in this location. The airborne geophysical maps used were the radiometric and magnetometric methods, which allowed the individualization of five radiometric domains and six magnetometric zones. Structural analysis identified four phases of deformation characteristic of a transpressional zone. The petrographic description showed that the lithology mineralogy is very similar, having as discriminating characteristics the degrees of deformation and the presence of some index minerals of the granulite facies. The lithogeochemical studies showed a context of high-K peraluminous to high-alumina calcine rocks, where the incompatible elements were responsible for the individualization of the BJ lithotypes due to lower ETR fractionation. The UPb geochronology determined crystallization ages for the basement rocks around 2.7-2.6 Ga (zircon U-Pb) and metamorphic peak at 2.07-2.06 Ga (U-Pb in zircon), with an age difference between the edge and center of the zircons with a range of 40-30 Ma, interpreted as the period between the metamorphic peak and orogenetic collapse. The present study proposes a modification of the boundary between blocks, based on the data set obtained by these methods.
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9
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VINÍCIUS ANSELMO CARVALHO LISBOA
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Shoshonitic magmatism in the Sergipano Orogenic System: Glória Norte Stock
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Advisor : HERBET CONCEICAO
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COMMITTEE MEMBERS :
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HERBET CONCEICAO
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DEBORA CORREIA RIOS
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MOACYR MOURA MARINHO
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CARLOS DINGUES MARQUES DE SÁ
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ADEJARDO FRANCISCO DA SILVA FILHO
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ROMULO MACHADO
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Data: Dec 13, 2019
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Show Abstract
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In the northern-central portion of the Sergipano Orogenic System there is an expressive Neoproterozoic granitic magmatism. These granites are, in part, medium- to high-k calc- alkaline and shoshonitic affinities. In the Macururé Domain (MD), the shoshonitic affinity plutons consist essentially of monzonites, with subordinate syenitic and granitic terms, and have crystallization ages between 588-631 Ma. In this plutonism, the volume of mafic enclaves is higher when compared to the calcalkaline magmatism of DM, being common to observe features that indicate coexistence and interaction between mafic and felsic magmas. In Gloria Norte Stock (GNS), the main representative of the shoshonitic plutons of MD, the enclaves are of three types: (i) mafic microgranular and (ii) minettes, which represent contemporary mafic magma pulses; and (iii) autolith, generated by the fragmentation of early cumulates, consisting predominantly of clinopyroxene.The mineral chemistry data and textural features observed in the amphiboles present in the mafic enclaves (MME) of GNS indicate that this is a primary phase that was rebalanced during the interaction between the basic-ultrabasic and intermediate magmas. Geochemical data show shoshonitic affinity (high K2O; alkali sum greater than 5%; K2O/Na2O > 1.22 and high Ba and Sr contents) for the monzonites and monzogranites studied, and ultrapotassic affinity (K2O> 3%, MgO> 3% and K2O/Na2O> 2) for MME. These rocks exhibit volcanic arc and post-collisional geochemical signature. Incompatible element enrichment and LREE-HREE fractionation show the need to consider an enriched mantle as a source of these magmas. Field and petrographic evidence, coupled with new geochemical, geochronological, and mineral chemistry data indicate that the ultrabasic and shoshonitic magmas were contemporary with granitic magmas, and that these magmas probably played an important role in the genesis of the granite.
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