Made available in DSpace on 2015-03-13T17:08:23Z (GMT). No. of bitstreams: 1 LindaraySC.pdf: 4257838 bytes, checksum: 9412fe333ae2e7c2ddef65c89e08a35e (MD5) Previous issue date: 2009-06-19 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The study area is located at the eastern-central portion of the Serid? Belt, on the interface between the Serid? Group Metasediments and the crystalline basement rocks of the Caic? Complex (RN). Petrographic and geochemical data allow us to define aspects related to the genesis and evolution of the Serra Verde Pluton magmas, which composes the goal of this dissertation The Serra Verde Pluton is a stock with outcropping area of about 25 km?, which is intrusive into metasedimentary sequence and the basement gneisses. The pluton intrusion is sintectonic to the Brasiliano event, elongated along the NE direction, developing a cornue geometry. The rock is a monzogranite mainly composed by K-feldspar, plagioclase and quartz, which usually compose more than 85% of the modal analisys. The main mafic mineral is the biotite, while amphibole, sphene, epidote, opaque minerals, allanite, zircon and apatite occur as accessory minerals. It features still a latemagmatic paragenesis composed by chlorite, granular epidote, carbonates and muscovite, developed through the percolation of late CO2 and H2O rich fluids. Chemically, the Serra Verde Pluton rocks may be classified as metaluminous, of calc-alkaline affiliation, sometimes showing trondhjem?tic characteristics, with high Na2O (>4,5%), Sr (>400ppm) and Ba (>800ppm) and low K2O (&#8804;3,0%), MgO (<1,0%), TiO2 (<0,5%), Rb (<90ppm), Y (&#8804;16ppm) and Zr (&#8804;13ppm). Micropetrographic evidences (mineral assembly and microtextures) indicate that the magma evolution occurred in moderated to high fO2 conditions, above the FMQ buffer. Thermo-barometric data obtained by minor elements geochemistry and the CIPW data, suggest a final/minimal pressure crystallization for the Serra Verde Pluton samples of about 3 to 5 kbar, liquidus temperature around 800o C, solidus temperature between 680o and 660o C. This data is compatible with those observed by many authors for the Neoproterozoic granites of the Serid? Belt. The group of analyzed data (Petrographic, microtextural and geochemical), suggests that the dominant process of the generation and evolution of the Serra Verde Granite magma was the fractional crystallization, probably from basement quartz-dioritic and tonalitic orthogneisses source / A ?rea estudada situa-se na por??o centro-leste da Faixa Serid?, na interface dos metassedimentos do Grupo Serid? e as rochas do embasamento cristalino do Complexo Caic? (RN). Dados petrogr?ficos e qeoqu?micos permitem definir os aspectos relativos ? g?nese e evolu??o do(s) magma(s) do Pl?ton Serra Verde, que constitui o alvo desta Disserta??o de Mestrado. O Pl?ton Serra Verde constitui um stock com ?rea aflorante de aproximadamente 25 Km2, intrusivo na seq??ncia metassedimentar e nos gnaisses do embasamento. Este pl?ton corresponde a uma intrus?o sintect?nica ao evento brasiliano, alongada na dire??o NE, com geometria en cornue. Trata-se de um monzogranito cuja assembl?ia mineral ominante ? composta por K-feldspato, plagiocl?sio e quartzo, que usualmente somam mais de 85% modal. Tem como m?fico principal a biotita, enquanto que anfib?lio itanita, ep?doto, opacos, allanita, zirc?o e apatita s?o os acess?rios. Apresenta ainda uma parag?nese tardi-magm?tica constiut?da de clorita, ep?doto granular, carbonato e muscovita, desenvolvida a partir da atua??o de flu?dos tardios ricos em CO2 e H2O. Quimicamente, as rochas do Pl?ton Serra Verde podem ser classificadas como metaluminosas, de filia??o c?lcio-alcalina, por vezes com caracter?sticas de associa??es trondhjem?ticas, com altos teores de Na2O (>4,5%), Sr (>400ppm) e Ba (>800ppm), e baixos teores de K2O (&#8804;3,0%), MgO (<1,0%), TiO2 (<0,5%), Rb (<90ppm), Y (&#8804;16ppm) e Zr (&#8804;13ppm). Evid?ncias micropetrogr?ficas (assembl?ias minerais e microtexturais) indicam que a evolu??o do magma ocorreu em condi??es de fO2 moderadas a elevadas, acima do tamp?o FMQ. Dados termobarom?tricos obtidos atrav?s da geoqu?mica de elementos menores, tra?os e dados normativos CIPW sugerem uma press?o final/m?nima de cristaliza??o para as amostras do Pl?ton Serra Verde em torno de 3 a 5 kbar, temperatura do l?quidus em torno de 800?C, e temperatura do solidus em torno 680 a 660?C. Estes dados s?o compat?veis com os observados por diversos autores em granit?ides neoproteroz?icos do Dom?nio Serid?. O conjunto de dados analisados (petrogr?ficos microtexturais e geoqu?micos), sugerem ainda que o processo dominante na gera??o e evolu??o do magma do granito Serra Verde se deu por cristaliza??o fracionada, sendo ortognaisses quartzo dior?ticos a tonal?ticos do complexo do embasamento, prov?veis candidatos para sua fonte

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-07-25T19:35:27Z No. of bitstreams: 1 AlanPereiraDaCosta_DISSERT.pdf: 24726684 bytes, checksum: 6b4523ea74314d3a8b4944c8fbeef8ad (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-07-28T21:11:34Z (GMT) No. of bitstreams: 1 AlanPereiraDaCosta_DISSERT.pdf: 24726684 bytes, checksum: 6b4523ea74314d3a8b4944c8fbeef8ad (MD5) / Made available in DSpace on 2016-07-28T21:11:35Z (GMT). No. of bitstreams: 1 AlanPereiraDaCosta_DISSERT.pdf: 24726684 bytes, checksum: 6b4523ea74314d3a8b4944c8fbeef8ad (MD5) Previous issue date: 2015-04-23 / A atividade plut?nica ediacarana, relacionada a orog?nese Brasiliana/Pan-Africana, constitui uma das mais importantes fei??es geol?gicas na Prov?ncia Borborema, representada em sua extens?o por in?meros bat?litos, stocks e diques. O Pl?ton Gran?tico Serra da Rajada (PGSR), principal objeto desse estudo, situado na por??o central do Dom?nio Rio Piranhas-Serid? representa um exemplo dessa atividade, sendo objeto de estudos cartogr?fico, petrogr?fico, litogeoqu?mico e geocronol?gico. Suas rochas s?o individualizadas em duas f?cies, sendo a f?cies gran?tica descrita como monzogranitos constitu?dos por K-feldspato, plagiocl?sio (oligocl?sico-An23-24%), quartzo e biotita (m?fico principal), tendo como minerais acess?rios opacos, titanita, allanita, apatita e zirc?o. Clorita, mica branca e carbonato s?o minerais de altera??o. A f?cies dior?tica compreende rochas formadas por quartzo diorito contendo plagiocl?sio (fase mineral dominante), quartzo e K-feldspato. Biotita e anfib?lio s?o os minerais m?ficos dominantes, e titanita, minerais opacos, allanita, zirc?o e apatita s?o os acess?rios. Contudo, os trabalhos de cartografia geol?gica tamb?m identificaram na regi?o a presen?a de outras unidades litoestratigr?ficas, descritas como gnaisses e migmatitos indiferenciados com lentes de anfibolitos relacionados ao Complexo Caic? (Paleoproterozoica) e rochas metassedimentares do Grupo Serid? (Neoproterozoico) compostos por paragnaisses com lentes de calciossilic?ticas, muscovita quartzitos e biotita xistos (respectivamente forma??es Jucurutu, Equador e Serid?), os quais s?o as encaixantes para as rochas do PGSR. Ainda foram identificados diques de leucomicrogranito e de pegmatitos, ambos relacionados ao final do magmatismo Ediacarano, bem como dep?sitos col?vio-eluviais e aluvionares relacionados ao Ne?geno e Quatern?rio, respectivamente. Dados litogeoqu?micos, na f?cies gran?tica do PGSR, evidenciam rochas bastante evolu?das (SiO2 69% a 75%), rica em ?lcalis (Na2O+K2O ? 8,0%), empobrecidas em MgO (? 0,45%), CaO (? 1,42%) e TiO2 (? 0,36%) e teores moderados de Fe2O3t (2,16 a 3,53%). Apresentam natureza transicional entre metaluminosa e peraluminosa (predom?nio do ?ltimo) e possuem afinidade subalcalina/monzon?tica (c?lcio-alcalina de alto K). Diagramas de Harker mostram correla??es negativas em Fe2O3t, MgO e CaO, indicando fracionamento de m?ficos e plagiocl?sio. O espectro de ETR mostra enriquecimento dos ETR leves com rela??o aos ETR pesados (LaN/YbN = 23,70 a 0,23), com anomalia negativa no Eu (Eu/Eu* = 0,70 a 0,23), sugerindo fracionamento ou acumula??o na fonte de feldspatos (plagiocl?sio). A integra??o dos dados permite correlacionar ?s rochas do PGSR ?quelas referidas na literatura como Su?te C?lcio-Alcalina de Alto K Equigranular. Considera??es sobre as condi??es de cristaliza??o para as rochas do PGSR foram obtidas a partir da integra??o de dados petrogr?ficos e litogeoqu?micos, os quais indicaram atua??o de condi??es moderadas a elevadas de ?O2 (parag?nese mineral titanita + magnetita + quartzo), magma progenitor saturado em H2O (cristaliza??o precoce das biotitas), atua??o de processos tardi-magm?ticos de fluidos ricos em ?CO2, H2O e O2 causando altera??es em parte da assembleia mineral (carbonata??o e saussuritiza??o dos plagiocl?sio, cloritiza??o das biotitas e esfenitiza??o dos opacos). Condi??es de termobarom?tricas foram estimadas com base em par?metros geoqu?micos (Zr e P2O5), bem como por minerais normativos CIPW, com resultados mostrando temperatura m?nima de liquidus da ordem de 800?C e temperatura de solidus da ordem de 700?C. As press?es final/m?nima de cristaliza??o sugerem ser da ordem de 3 a 5 Kbar. A presen?a de minerais zonados (plagiocl?sio e allanita) associadas a dados litogeoqu?micos diagramas bi-log para Rb vs Ba e Rb vs Sr sugerem a atua??o da cristaliza??o fracionada como processo dominante na evolu??o magm?tica do PGSR. Estudos geocronol?gicos U-Pb e isot?picos Sm-Nd indicam, respectivamente, que o biotita monzogranito possui idade de cristaliza??o de 557?13 Ma, com idade modelo TDM de 2,36 Ga, tendo valor de eNd para a idade de cristaliza??o de -20,10, permitindo inferir fonte crustal paleoproterozoica para o magma. / The ediacaran plutonic activity related to the Brasilian/Pan-African orogeny is one of the most important geological features in the Borborema Province, represented along its extension by numerous batholiths, stocks, and dikes.The object of this study, the Serra Rajada Granitic Pluton (SRGP), located in the central portion of the Piranhas-Serid? River Domain is an example of this activity. This pluton has been the subject of cartographic, petrographic, geochronological and lithogeochemical studies and its rocks were characterized by two facies. First, the granitic facies were described as monzogranites consisting of K-feldspar, plagioclase (oligoclase - An23-24%), quartz and biotite (main mafic) and opaque minerals such as titanite, allanite, apatite, and zircon as accessories. Alteration minerals are chlorite, white mica and carbonate. Second, the dioritic facies consist of rocks formed by quartz diorite containing plagioclase (dominant mineral phase), quartz and K-feldspar. Biotite and amphibole are the dominant mafic minerals; and titanite, opaque minerals, allanite, zircon and apatite are the accessories. However, previous geological mapping work in the region also identified the presence of other lithostratigraphic units. These were described as gneisses and migmatites with undifferentiated amphibolite lenses related to the Caic? Complex (Paleoproterozoic) and metasedimentary rocks of the Serid? Group (Neoproterozoic) composed of paragneiss with calc-silicate lenses, muscovite quartzite and biotite schist (respectively, the Jucurutu formations, Equador and Serid?), the host rocks for the SRGP rocks. Leucomicrogranite and pegmatite dikes have also been identified, both related to the end of the Ediacaran magmatism and colluvial- eluvial and alluvial deposits related to Neogene and Quaternary, respectively. Lithogeochemical data on the SRGP granite facies, highlighted quite evolved rocks (SiO2 69% to 75%), rich in alkalis (Na2O+K2O ? 8.0%), depleted of MgO (? 0.45%), CaO (? 1.42%) and TiO2 (? 0.36%) and moderate levels of Fe2O3t (2.16 to 3.53%). They display transitional nature between metaluminous and peraluminous (predominance of the latter) with sub-alkaline/monzonitic (High K calcium-alkali) affinity. Harker diagrams show negative correlations for Fe2O3t, MgO, and CaO, indicating mafic and plagioclase fractionation. REE spectrum shows enrichment of LREE relative to heavy REE (LaN/YbN = 23.70 to 10.13), with negative anomaly in the Eu (Eu/Eu* = 0.70 to 0.23), suggesting fractionation or accumulation in the feldspars source (plagioclase). Data integration allows to correlate the SRGP rocks with those described as Calcium-Alkaline Suite of equigranular High K. The crystallization conditions of the SRGP rocks were determined from the integration of petrographic and lithogeochemical data. These data indicated intermediate to high conditions of ?O2 (mineral paragenesis titanite + magnetite + quartz), parent magma saturated in H2O (early biotite crystallization), tardi-magmatic processes of fluids rich in ?CO2, H2O and O2 causing part of the mineral assembly to change (plagioclase carbonation and saussuritization, biotite chloritization and opaques Sphenitization). Thermobarometrical conditions were estimated based on geochemical parameters (Zr and P2O5) and CIPW normative minerals, with results showing the liquidus minimum temperature of about800?C and the solidus temperature of approximately 700?C. The final/minimum crystallization pressure are suggested to be between 3 and 5 Kbar. The presence of zoned minerals (plagioclase and allanite) associated with lithogeochemical data in bi-log diagrams for Rb vs. Ba and Rb vs. Sr suggest the role of fractional crystallization as the dominant process in the magmatic evolution of SRGP. U-Pb Geochronological and Sm-Nd isotope studies indicated, respectively, the crystallization age of biotite monzogranite as 557 ? 13 Ma, with TDM model age of 2.36 Ga, and ?Nd value of -20.10 to the crystallization age, allowing to infer paleoproterozoic crustal source for the magma.