Дисертації з теми "Sm-Nd geochronology"
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Nogueira, Shayenne Fontes. "Petrologia, geocronologia (U-Pb SHRIMP) e geologia isotópica (Sm-Nd) do granito aquidabã- arco magmático amoguijá-terreno rio Apa- Sul do Cráton Amazônico." Universidade Federal de Mato Grosso, 2015. http://ri.ufmt.br/handle/1/113.
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CNPq
O Terreno Rio Apa é marcado por uma história evolutiva complexa e ainda contêm problemáticas a serem estudadas e compreendidas. Neste trabalho são apresentados os resultados obtidos a partir da caracterização petrológica do Granito Aquidabã que pertence à Suíte Intrusiva Alumiador inserida no Arco Magmático Amoguijá deste terreno. Em um contexto anterior, as rochas deste granito eram descritas como pertencentes ao Batólito Alumiador, porém, as mesmas apresentam características singulares que levaram à sua individualização. O Granito Aquidabã está representado por rochas plutônicas e efusivas, de natureza ácida. São classificadas como dacitos e riolitos, riolitos/riolitos alcalinos e adamelitos (monzogranitos)/granitos, subdivididos em três fácies petrográficas: Granito Gráfico (fácies 1), Subvulcânicas Dacítica-Riolítica (fácies 2), Microgranito (fácies 3). A primeira é, volumetricamente, dominante no corpo mapeado sustentando as partes mais elevadas, e disposta na porção central da Serra da Alegria; caracteriza-se por rochas maciças e de cor rosa a rosa-acinzentado, leucocráticas, equi- a inequigranulares média a fina. A fácies 2 é caracterizada pela ocorrência de litotipos que variam de dacitos a riolitos.Os dacitos apresentam-se marrom-acinzentado, com textura porfirítica, destacando fenocristais de plagioclásio e quartzo, por vezes com dimensões entre 1 e 7 mm apresentando, comumente, feições de corrosão magmática como golfos e embaiamentos, envoltos por uma matriz felsítica cinza. Os riolitos são rosa-acinzentado, maciços, afaníticos, com variedades porfiríticas, apresentando fenocristais de feldspato alcalino com tamanhos entre 1 e 5 mm envoltos por uma franja esferulítica de composição quartzo+K-feldspato. A fácies Microgranito (fácies 3) é a de menor representatividade, sendo encontrada nas bordas oeste e sudoeste do corpo granítico, caracterizada por rochas maciças cinza-claro, inequigranulares fina a muito fina. Os dados geoquímicos sugerem um magmatismo de composição compatível com a de granitoides tipo A gerados em ambiente de arco magmático, em período pós-tectônico. Através do método geocronológico U-Pb (SHRIMP) em zircão se obteve idade de 1811±6,8 Ma para o Granito Aquidabã, com valores εNd (1,81Ga) de -2,18; -4,37 e -1,50, e idade modelo TDM de 2,35, 2,57 e 2,26 Ga que apontam para participação de uma fonte crustal na origem do magma, possivelmente envolvendo processos de fusão parcial de uma crosta continental neoarqueana a paeloproterozoica na geração do granito. Os resultados obtidos apontam que o Granito Aquidabã corresponde a um magmatismo desenvolvido no final do Orosiriano no Arco Magmático Amoguijá.
The Rio Apa Terrane is marked by a complex evolutionary history and still contain issues to be studied and understood. This paper presents the results obtained from the petrologic characterization of Aquidabã granite belonging to Intrusive Suite Alumiador inserted into the Magmatic Arc Amoguijá. In a previous context, this granite rocks were described as belonging to the Batholith Alumiador, however, they present unique characteristics that led to its individualization. The Aquidabã Granite is represented by plutonic and effusive rocks, acidic in nature. They are classified as dacites and rhyolites, rhyolites / alkaline rhyolites and adamelitos (monzogranites) / granite, divided in three petrographic facies: Graphic Granite (facies 1), Subvolcanic Dacitic-Riolítica (facies 2), Microgranito (facies 3). The first is volumetrically dominant in the body, arranged in the central portion of the Serra da Alegria; It characterized by massive rocks and pink , pink-gray, leucocratic, inequigranular thin.The facies 2 is characterized by the occurrence of rock types ranging from the dacites, dacites/riolitos. Have color grayish to brown, with phenocrysts of quartz and plagioclase, sometimes with dimensions between 1 and 7 mm, presenting features magmatic corrosion as gulfs and embayments, surrounded by a gray matrix felsítica.The rhyolites are pink-gray, massive, afaníticos with porphyritic varieties, with phenocrysts of alkali feldspar with sizes between 1 and 5 mm surrounded by a fringe spherulitic quartz K-feldspar + composition. The Microgranito facies (facies 3) is the smaller representation, found in the western and southwestern edges of the granite body, characterized by light gray massive rocks, thin inequigranular very thin. The geochemical data suggest a composite magmatism compatible with the granitic type A generated in magmatic arc environment in post-tectonic period. Through the method geochronological U-Pb (SHRIMP) was obtained zircon age ± 6.8 1811 Ma to Aquidabã Granite with εNd values (1,81Ga) of -2.18; -4.37 And -1.50, and TDM model age of 2.35, 2.57 and 2.26 Ga pointing to involvement of a crustal magma source in origin, possibly involving partial melting processes of continental crust neoarqueana the paeloproterozoica in granite generation. The results suggest that the Aquidabã Granite corresponds to a magmatism developed in the late Orosirian in Magmatic Arc Amoguijá.
Redes, Letícia Alexandre. "Granito Taquaral : evidências de um arco magmático orosiriano no sul do Cráton Amazônico na região de Corumbá - MS." Universidade Federal de Mato Grosso, 2015. http://ri.ufmt.br/handle/1/117.
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O Granito Taquaral possui dimensões batolíticas, localiza-se no sul do Cráton Amazônico, na região de Corumbá, extremo ocidente do estado de Mato Grosso do Sul, próximo ao limite Brasil-Bolívia, sendo parcialmente recoberto pelas rochas sedimentares das formações Urucum, Tamengo, Bocaina e Pantanal e pelas as Aluviões Atuais. Com base no estudo das rochas do Granito Taquaral a partir de granulação, cor e composição, juntamente com o mapeamento geológico de detalhe, foi realizada a identificação de três fácies petrográficas: Fácies Média a Grossa Cinza, Fácies Grossa Rosa e Fácies Fina Rosa. A primeira é, volumetricamente, dominante no corpo mapeado; caracteriza-se por rochas leucocráticas, de cor cinza, textura inequi a equigranular média a grossa, às vezes, mostra-se milonitizada e são classificadas como quartzo-monzodiorito, granodiorito e monzogranito. A segunda é constituída por rochas leucocráticas de cor rosa, inequigranulares, grossas, de composição quartzo-monzonito e monzogranito. Enquanto que a terceira é composta por rochas hololeucocráticas de cor rosa-claro, equi a inequigranulares classificadas como monzo a sienogranítica, de granulação fina e representadas por diques aplíticos. Localmente são encontrados dois tipos de enclaves de natureza e origens diferentes, um de composição máfica, corresponde a xenólito e outro, identificado como Enclave Microgranular Félsico. Na área de estudo são encontrados, também diques de diabásio sempre em contatos abruptos com o granito. Foram identificadas duas fases deformacionais, uma de natureza dúctil (F1) e outra rúptil/rúptil-dúctil (F2). Os dados geoquímicos indicam composição intermediária a ácida para essas rochas e sugerem sua colocação em ambiente de arco, representando um magmatismo cálcio-alcalino de médio a alto-K, metaluminoso a peraluminoso. Através do método geocronológico U-Pb (SHRIMP) em zircão se obteve idade de 1861±5,3 Ma para sua cristalização. Análises Sm-Nd em rocha total fornecem valores de εNd(1,86 Ga) de -1,48 e -1,28 e TDM de 2,32 e 2,25 Ga apontando para uma provável fonte crustal riaciana. Os resultados obtidos apontam que o Granito Taquaral corresponde a um magmatismo desenvolvido no final do Orosiriano no Arco Magmático Amoguijá.
The Taquaral Granite comprises an intrusion of batholithic dimensions, located in the south of the Amazon Craton in Corumbá region - far west of the state of Mato Grosso do Sul, near the border between Brazil and Bolivia -, partially covered by sedimentary rocks of the Urucum, Tamengo, Bocaina and Pantanal formations and the Alluvial Deposits. Based on grain size, color, and composition along with detailed geological mapping, three petrographic facies are attributed to the rocks of Taquaral Granite: Medium to Coarse-grained Grey Facies, Coarse-grained Pink Facies and Fine-grained Pink Facies. The first facies is volumetrically dominant in the mapped body; characterized by leucocratic rocks, grey, inequigranular to equigranular medium-to-coarse grained, sometimes displaying a mylonitized texture and are classified as quartz-monzodiorite, granodiorite and monzogranite. The second facies consists of pink leucocratic rocks, inequigranular, coarse-grained, of quartz monzonite and monzogranite composition. In turn, the third facies consists of light-pink hololeucocratic rocks, equigranular to inequigranular, classified as fine-grained aplite dykes of monzogranitic to syenogranitic composition. Two different types of enclaves are locally found: one corresponds to a mafic xenolith; another is identified as felsic microgranular enclave. In the study area, diabase dikes are also found, always in direct contact with the granite. Two deformation phases are identified, one of ductile behaviour (F1) and another of brittle / ductile brittle behaviour (F2). Geochemical data indicate intermediate to acid composition for these rocks and suggest an arc environment, representing a medium to high-K calc-alkaline magmatism, metaluminous to peraluminous. SHRIMP U-Pb zircon ages of 1861 ± 5.3 Ma are attributed to crystallization. Sm-Nd whole rock analyses provided negative εNd(1.86 Ga) values (-1.48 and -1.28) and TDM model ages from 2.32 to 2.25 Ga indicating a Rhyacian crustal source. The results indicate that Taquaral Granite is an evidence of a magmatism developed in the Amoguijá Magmatic Arc in late Orosirian.
Fachetti, Frankie James Serrano. "Magmatismo cálcio - alcalino calimiano no embasamento do terreno Jauru (Província Rondoniana San Ignácio), Craton Amazônico : geoquímica e geocronologia Sm-Nd e U-Pb." Universidade Federal de Mato Grosso, 2015. http://ri.ufmt.br/handle/1/121.
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O Ortognaisse Taquarussu e o Granodiorito Guadalupe, integrantes do embasamento da Província Rondoniana - San Ignácio, SW do Cráton Amazônico, norte do município de Jauru- MT, correspondem a corpos orientados segundo um trend principal NW/SE. São rochas de composição granodiorítica com ocorrências subordinadas de monzogranitos. Na petrografia, são rochas de granulação fina a grossa, constituídas essencialmente por plagioclásio, quartzo, microclina, ortoclásio e biotita. Os minerais acessórios são: anfibólio, titanita, granada, apatita, epidoto, zircão e opacos. Apresentam evidências de pelo menos três fases de deformação dúcteis onde a principal estrutura relacionada a fase D1 é a foliação S1, representada ora por um bandamento composicional, ora por uma xistosidade. A segunda fase corresponde a uma clivagem de crenulação que transpõe a foliação S1, A terceira fase é exemplificada pela implantação de zonas de cisalhamento que geraram uma foliação/faturamento de escala local. O estudo geoquímico permitiu classificar as rochas como granodioritos e monzogranitos, oriundos de um magmatismo intermediário a ácido, de caráter sub-alcalino, da série cálcio-alcalina a cálcio-alcalina alto K, com índices de alumina que varia de metaluminoso a levemente peraluminoso. Foram classificados como gerados em ambiente de arco de ilhas e os dados U-Pb (Shrimp em zircão) mostram uma idade concórdia de 1575±6Ma. A idade modelo das análises de Sm-Nd (TDM) apontam para 1,63Ga, com εNd (t=1,57Ga) variando entre -1,52 e +0,78. Estes dados permitem caracterizar estas rochas como uma crosta juvenil com uma possível contaminação de rochas crustais.
The Taquarussu orthogneiss and the Guadalupe Granodiorite part of Rondonian-San Ignacio Province basement, southweast of Amazonian Craton, correspond to oriented bodies according to a NW/SE trend. The rocks are granodiorite composition with subordinate monzogranites, fine to coarse grained, consisting essentially of plagioclase, quartz, microcline, orthoclase and biotite. The accessory minerals are amphibole, titanite, garnet, apatite, epidote, zircon and opaque minerals. There is evidence of at least three phases of ductile deformation where the main structure is related to D1 stage (foliation S1), represented by a compositional banding, or by schistosity. The second phase is a crenulation cleavage transposing the foliation S1 and the third phase is exemplified by the deployment of shear zones that generated a foliation/fracturing on a local scale. The geochemical study indicates that the rocks are classify as granodiorites and monzogranites, coming from an intermediate to acid magmatism, sub-alkaline character calc-alkaline to high-K calc-alkaline series, with alumina ratios ranging from metaluminous to lightly peraluminous. The rocks were generate in a volcanic islands arc environment and the UPb data (Shrimp zircon) show a concord age 1575 ± 6Ma. The Sm-Nd model age (TDM) is 1.63Ga with εNd (t = 1.57Ga) ranging between -1.52 and +0.78. These data indicate that these rocks probably are a juvenile crust with a possible contamination of crustal rocks. Keyword: Geology, Gneiss Taquarussu, Granodiorite Guadalupe.
Farrell, Thomas. "Investigating the Tectonic Significance of Spiral Garnets from the Betic-Rif Arc of Southern Spain and Northern Morocco Using Sm-Nd Garnet Geochronology:." Thesis, Boston College, 2019. http://hdl.handle.net/2345/bc-ir:108592.
Повний текст джерелаSpiral garnets are well-documented metamorphic microstructures that have been observed in orogens throughout the world. The preferred orientation of spiral garnet axes has been proposed (Bell and Johnson, 1989) to record and preserve information about the timing, rate, and orientation of the tectonic-scale processes. Using the model of Be Spiral garnets are well-documented metamorphic microstructures that have been observed in orogens throughout the world. The preferred orientation of spiral garnet axes has been proposed (Bell and Johnson, 1989) to record and preserve information about the timing, rate, and orientation of the tectonic-scale processes. Using the model of Bell and Johnson (1989), Aerden et al. (2013) proposed a link between the preferred orientation of spiral garnets and changes in relative plate motion between Iberia and Africa. The goal of this thesis is to this relationship by absolutely dating, eight samples from the Betic-Rif arc with measurable spiral axis orientations were chosen for Sm-Nd garnet geochronology. Chapter one is a detailed literature review of prior work on the formation and interpretation of spiral garnets. In chapter two we present 11 bulk Sm-Nd garnet ages from eight samples, these ages range from 35.6 ± 2.8 to 13.62 ± 0.69 Ma. The results from the obtained bulk garnet ages reveal a more complex relationship between FIA orientations and plate motion that originally hypothesized in Aerden et al. (2013). Large-scale rigid block rotations that postdate garnet growth may have influenced the current orientation of FIA from the western Betic-Rif. In chapter three, zoned geochronology was conducted on a single sample from the Nevado-Filabride Complex. This study revealed spiral garnet formation occurring on a rapid timescale, just 〖0.45〗_(-0.32)^(+0.51) Myr. While other zoned garnet studies have shown similar rapid growth in subduction zone setting (Dragovic et al., 2012), this is the first such documentation of such rapid growth from a garnet hosting spiral inclusion trails in a regional metamorphic setting. We calculated strain rates considering different genetic models for the spiral inclusion trails either by garnet rotation in simple shear, or by episodic overgrowth of suborthogonal crenulation cleavages due to switching stress axes. In both cases a similar fast strain rate of ca. 10-13 s-1 was obtained, which is an order of magnitude faster than typical regional strain rates and faster than previous spiral garnet studies regardless of the method used to calculate strain-rate
Thesis (MS) — Boston College, 2019
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Earth and Environmental Sciences
Quinn, Ryan Joel. "THE EVOLUTION OF GRENVILLE BASEMENT IN THE EASTERN GREAT SMOKY MOUNTAINS; CONSTRAINTS FROM U-PB ZIRCON GEOCHRONOLOGY, WHOLE ROCK SM-ND, AND FELDSPAR PB GEOCHEMISTRY." UKnowledge, 2012. http://uknowledge.uky.edu/ees_etds/7.
Повний текст джерелаKendall, Jamie. "Sm/Nd garnet geochronology and pressure-temperature paths of eclogites from Syros, Greece: Implications for subduction zone processes and water loss from the subducting slab." Thesis, Boston College, 2016. http://hdl.handle.net/2345/bc-ir:107239.
Повний текст джерелаSamarium/Neodymium (Sm-Nd) garnet geochronology of eclogites from Syros, Greece provides constraints on timing of peak metamorphism while thermodynamic modeling of the same samples allows a comparison of pressure-temperature (P-T) paths. Sm-Nd geochronology of four eclogite samples give ages of 48.8 ± 3.2 Ma (high 147Sm/144Nd = 0.49, n = 6, MSWD = 0.67), 48.1 ± 2.3 Ma (high 147Sm/144Nd = 1.22, n = 4, MSWD = 2.4), 44.7 ± 1.0 Ma (high 147Sm/144Nd = 3.9, n = 6, MSWD = 1.4), and 43.6 ± 1.6 Ma (high 147Sm/144Nd = 1.39, n = 6,MSWD = 2). These garnet growth ages span several million years and are younger than the only other published garnet eclogite ages from the island which use Lutetium/ Hafnium (Lu-Hf) garnet geochronology to place peak metamorphism at ~52 Ma (Lagos et al, 2007). Another eclogite sample dated less precisely yielded an age of 57.7 ± 6.3 Ma (high 147Sm/144Nd = 0.40, n = 10, MSWD = 1.9), significantly older than the other garnets dated in this study. The garnet ages from eclogites presented here suggest that high pressure-low temperature metamorphism, and related garnet growth and dehydration, on Syros lasted ~9 myr, similar to what has been reported for nearby Sifnos Island (Dragovic et al., 2015). Thermodynamic modeling of three samples reveals similar prograde P-T paths despite differences in tectonic setting and chemistry between samples. Water loss from mineral breakdown during the span of subduction zone garnet growth varies between samples from 1.09 to 5.13 weight percent but is greatest for the most ultramafic sample due to chlorite stability permitting greater capacity for water to be carried to depth. P-T paths reach greater maximum pressures (up to 2.42 GPa) than what is reported for Sifnos island (Dragovic et al., 2015) and greater than most previously published pressure estimates for Syros (ie. Okrusch and Bröcker, 1990; Putlitz et al., 2005)
Thesis (MS) — Boston College, 2016
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Earth and Environmental Sciences
Santos, Gustavo Macedo de Paula. "Quimioestratigrafia isotópica (C, O, Sr) e geocronologia (U-Pb, Sm-Nd) das rochas da Formação Sete Lagoas, Grupo Bambuí." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/44/44141/tde-10022014-110652/.
Повний текст джерелаRecently published geochronological data has arisen questions on the Sete Lagoas Formation (SLF) depositional evolution. This unit is mainly composed by carbonate rocks with subordinated pelitic intercalations and represents the basal unit of the Bambuí Group, which overlies the glacial deposits of the Jequitaí Formation in the São Francisco Craton (SFC). This study combines isotope chemostratigraphy (C, O, Sr) and geochronology (U -Pb and Hf on detrital zircons and Sm-Nd on whole rock samples) in five sections of the SLF in the Lagoa Santa (MG) region, southern part of SFC, in order to answer such questions. Vespasiano (VS) and Ana Paula (AP) sections are composed by gray limestones and beige dolostones, with high contents of detrital sediments and poor in organic matter. The most representative \'delta\'\'POT.13C\' values obtained oscillate within a narrow range around 0%o. These data allow positioning these sections in the first depositional sequence of the SLF, above the basal Sturtian cap carbonates (~740 Ma) of this unit. Bairro da Lapinha (BL), Pedra do Baú (BAU) and Parque da Gruta da Lapinha (PGL) sections comprises dark gray to black limestones, with low detrital sediments contents and rich in organic matter. They are characterized by very positive \'delta\'\'POT.13\'C values (> 6%o) and \'87 ANTPOT.Sr\'/ \'86 ANTPOT.Sr\' ratios close to 0.7075. These sections belong to the second sequence of the SLF. Detrital zircons were retrieved from three marl samples from sections VS, AP and PGL and dated by the U-Pb method. The results indicate that the siliciclastic sediments of the SLF come from sources of long crustal residence time located in the Araçuaí-West Congo Orogen. The youngest population is 557 Ma aged and sets the maximum depositional age for the second sequence of SLF and most of the Bambuí Group. Furthermore, younger concordant zircon grains with ages of 537 ± 4 Ma and 506 ± 7 Ma for the first and second sequence, respectively, refute the hypothesis of a major sedimentation gap between the sequences, as recently proposed, and endorse an Ediacaran/Cambrian age for the SLF. If such gap does exist, it lies between the Sturtian cap carbonates and the sections with \'delta\'\'POT.13\' C around 0%o. These ages also indicate that the deposition of most of the Bambuí Group took place in a foreland basin, after the closure of the Adamastor Ocean which led to the edification of the Araçuaí Belt to the east of the SFC. The \'87 ANTPOT.Sr\'/ \'86 ANTPOT.Sr\' ratios obtained on the SLF carbonates contrast with the recently proposed Sr evolution curves, especially for the Cambrian, from where ratios higher than 0.7085 would be expected. It is possible that the SLF was deposited on a restricted eipiric sea and global correlations based on Sr isotopes are not reliable in such cases.
Figueiredo, Milene Freitas. "Quimioestratigrafia isotópica (C, O, S e Sr), geocronologia (Pb-Pb e K-Ar) e proveniência (Sm-Nd) das rochas da Faixa Paraguai Norte, Mato Grosso." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/44/44141/tde-23012011-172059/.
Повний текст джерелаExpressive biogeochemical anomalies have been recognized in Neoproterozoic marine rocks deposited worldwide, with no similar record throughout the Phanerozoic. The interest in this Era have been increased, especially on the Ediacaran time, the period that precedes the great CambrianLife Explosion, and houses the first macroscopic organisms, which are known as the Ediacaran Fauna. Thus, the understanding of paleoclimatic and paleoenvironmental conditions, associated with the establishment of the chronology of the events is crucial in the understanding the evolution of biota on the planet during this period. The rocks of northern Paraguay Belt in the study area record the occurrence of two glaciations, where one is Cryogenian and another is Ediacaran (Puga and Serra Azul formations). These glacial deposits are separated by a thick carbonate platform (Araras Group), which records biogeochemical anomalies in the Ediacaran seawater. These rocks were deposited in the southeastern margin of the Amazonian Craton, in the time interval between the breakup of the Rodinia Paleocontinent and the assemblage of the Gondwana. This work is composed by five articles, whose study scopes are: i) detailed isotope chemostratigraphy (C, O, S and Sr) in carbonates from the Araras Group and the Serra Azul Formation; ii) provenance (Sm-Nd) of the siliclastic rocks from the Puga and the Serra Azul Formations and the base of the Raizama Formation; and iii) geochronology (Pb-Pb in carbonate and K-Ar in volcanic clasts) from the Serra Azul Formation. The \'delta\'\'POT.13 C\' values showed two post-glacial negative anomalies (ca. - 6%o) and a gradient of up to 2.5%o along the basin, during interglacial period. The obtained \'ANTPOT.87 Sr\'/\'ANTPOT.86 Sr\' ratios (between 0.7074 and 0.7087) showed a consistent trend with that expected for the Ediacaran sea water. The trace sulfate extracted from obtained carbonates yielded \'delta\'\'POT.34 S\' values from 22 to 61%o, whereas the pyrites ranged between 11 and 43%o. These \'delta\'\'POT.34 S\' values are the heaviest ever recorded in geologic time (above 48 and 30, respectively). The Sm-Nd model ages (\'T IND.DM\') obtained from siliciclastic rocks from Puga, Serra Azul and Raizama formations range from 1.6 to 2.2 Ga, and indicate a variable contribution along the section, with predominant sources coming from areas at north and east of the precursor basin. Recovered volcanic clasts from the Serra Azul Formation yielded K-Ar ages between 730 and 1167 Ma, revealing a non expected young source for areas on the Amazon Craton. The Pb-Pb isochron age of 596 ± 26 Ma was determined in carbonates from the Serra Azul Formation and corroborates its correlation with Gaskiers Glaciation which was dated at 580 Ma.
Campos, Roberto Sacks de. "Petrologia, caracterização geológica, geoquímica e geocronológica do magmatismo pré, sin e pós-colisional presente no Complexo Metamórfico Brusque nas regiões de Itapema e Botuverá, Santa Catarina, Brasil." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/32594.
Повний текст джерелаThis work objective the characterization of the petrology, geochemistry, geochronology and metamorphism of ortoderivate rocks that belong to Brusque Metamorphic Complex BMC) in two regions: Itapema and Botuverá, Santa Catarina, Brazil. Within these, good expositions of mafic and metaultramafic rocks occur in both regions. In Itapema, bodies of peraluminous leucogranites were also investigated. Around Botuverá were investigated diabase dikes and lamprophyres. The analysis of the conditions of generation and sources of magmatic events responsible for the development of these rocks was essential for the characterization and assessment of the significance of these tectonic units in the BMC, and it were placed during the pre-, syn-and post-collisional period of it’s evolution. The regional foliation of the complex is represented by a low angle S2 surface in Itapema region and a higher angle foliation in the region of Botuverá, folded by actuation of the D3 event. Petrography and Hb-Pl geothermometry data indicate that the main foliation of the mafic schists was generated in conditions between the transition of greenschist and lower amphibolite facies. The pre-orogenic magmatism of the Brusque Metamorphic Complex consists of lenses of mafic-ultramafic, products from the metamorphism of basalts, gabbros, related cumulate rocks and volcanogenic sediments. These rocks have a tholeiitic affinity and high contents of LREE and LILE elements. The analysis of incompatible elements ratios, the position of igneous bodies intercalated with the metasediments and the absence of oceanic crust suggest that the basalts were placed in an intra-continental plate environment, synchronous with sedimentation of the basin. The initial εNd values between -2.96 and 5.05 for the metavolcanics of Itapema and between -0.14 and -6.97 for the rocks of Botuverá indicate the involvement of Paleoproterozoic crust on the genesis of these magmas. The generally high 87Sr/86Sr values justify the involvement of crust, and the highest values found in Botuverá, highlight the greater involvement of this component in the region. Syn tectonic magmatism is represented by bodies of peraluminous leucogranite showing emplacement concordant to S2 foliation. Compositional parameters of these rocks characterized by low ratios K2O/Na2O, CaO/Na2O and LaN / YbN, low levels of Rb, Sr, Zr, Y, Yb and Lu, are consistent with magmas generated from partial melting of pelitic rocks, with limited participation of differentiation processes. In the region of Botuverá the occurrence of diabase dykes and lamprophyres cutting the regional metamorphic units indicates that its position is post-collisional. Geochemically show affinity between the tholeiitic and shonshonitic series. The distribution pattern of trace elements and the Th/Yb for Ta/Yb ratios indicate that extraction of diabase occur from an enriched mantle source, with the presence of rutile and garnet in the residue and heavily contaminated by crust. These characteristics are similar to those found in rocks post-collisional basaltic volcanic in south Brazil. The scattered values of єNd (618) in basic terms, ranging between -13.74 and +5.52 highlight the heterogeneity of mantle supply and reinforce the importance of crustal component in the generation of these rocks. A concordant age of 618 ± 8.7 Ma by U-Pb (LA-ICP-MS) zircon method were obtained, marking a early magmatic processes of post-collisional Brasiliano orogeny in the region of Botuverá.
Romano, Antônio Wilson. "Évolution tectonique de la région nord-ouest du quadrilatère ferrifère : Minas Gerais-Brésil (Géochronologie du socle, aspects géochimiques et pétrographiques des supergroupes Rio Das Velhas et Minas)." Nancy 1, 1989. http://www.theses.fr/1989NAN10364.
Повний текст джерелаStewart, Emily Mavis. "Microstructural and tectonic applications of texturally-controlled Sm/Nd garnet geochronology." Thesis, 2015. https://hdl.handle.net/2144/14027.
Повний текст джерелаDragovic, Besim. "Constraining the rates and timescales of garnet growth and associated dehydration during metamorphism." Thesis, 2013. https://hdl.handle.net/2144/15058.
Повний текст джерелаTravers, D. C. "Geochronology, geochemistry and petrogenesis of mafic magmatism in the Coompana Province." Thesis, 2015. http://hdl.handle.net/2440/118238.
Повний текст джерелаThe Coompana Province between the Gawler Craton in South Australia and the Yilgarn Craton in Western Australia is one of the least understood geological regions in Australia. Recent work by Spaggiari and Smithies (2015) suggests that the known crustal precursors in the Coompana Province originated in a new crustal generation event at ca. 1900 Ma. This new juvenile crustal element then evolved through three distinct reworking and magmatic events at ca. 1610 Ma, ca. 1500 Ma, and between ca. 1192 – 1150 Ma (Wade et al., 2007; Spaggiari and Smithies, 2015). Dating of mafic volcanics underlying the Bight Basin in the south-eastern Coompana Province using the Sm-Nd mineral isochron method has revealed a fourth distinctive episode of mafic magmatism at ca. 860 Ma. The geochemical and Nd-isotopic signatures of ca. 860 ma mafic magmatism, including Nb and Ti anomalies, LREE enrichment, K-anomalies, and highly evolved εNd(860Ma) values between -9.9 and -12.7 provide evidence for assimilation and reworking of subduction/arc related Coompana Province crust. Magmatism at ca. 860 Ma in the Coompana Province was most likely coeval with widespread magmatism that occurred over Central and Southern Australia between ca. 800 – 830 Ma. Magmatism during this period was associated with the NE-SW directed intracratonic extension that resulted in the Centralian Superbasin and produced various suites of mafic volcanics and intrusives referred to collectively as the Willouran Basic Province. We suggest that the Willouran Basic Province now be extended to include the ca. 860 Ma mafic volcanics and intrusives in the south-eastern Coompana Province.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2015
Trestrail, J. L. "U-Pb detrital zircon, geochemical and Nd isotope constraints on sedimentary provenance of the Chewings Range Quartzite, Warumpi Province, Arunta Region, NT." Thesis, 2010. http://hdl.handle.net/2440/106279.
Повний текст джерелаThe Chewings Range Quartzite is a meta-sedimentary cover sequence located in the Warumpi Province of the Arunta Region. U-Pb detrital Zircon analysis of the Chewings Range Quartzite indicates a minimum depositional age of ~ 1640Ma, with the main population of zircons residing within a range of 1700 – 1800Ma. Evidence from Sm-Nd isotopic data suggests that a series of Staurolite Garnet Schists, often grouped with the Chewings Range Quartzite, has a significantly more juvenile character. This suggests that it may represent a new unit with a significantly differing provenance to that of the Chewings Range Quartzite. Combined REE, geochemistry and detrital zircon dating suggests that the Chewings Range Quartzite was derived primarily off the Arunta Region and North Australian Craton, while the Stauralite Garnet Schists holds more affinity with juvenile Musgrave Province to the south.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2010
Van, Wyck Nicholas. "Oxygen and carbon isotopic constraints on the development of eclogites, Holsn/oy, Norway and major and trace element, common Pb, Sm-Nd, and zircon geochronology constraints on petrogenesis and tectonic setting of pre- and early proterozoic rocks in Wisconsin." 1995. http://catalog.hathitrust.org/api/volumes/oclc/32642090.html.
Повний текст джерелаRobinson, Frank Alexander. "Geochronological and geochemical constraints on the lithospheric evolution of the Arabian shield, Saudi Arabia: understanding plutonic rock petrogenesis in an accretionary orogen." Thesis, 2014. http://hdl.handle.net/2440/84674.
Повний текст джерелаThesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2014
Küstner, Wolfgang. "K-Ar-Datierungen an detritischen Muskoviten und Sm-Nd-Modellalter prä- und synorogener schwach metamorpher Sedimente im Rhenoherzynikum - Grundlegende Daten zur Quantifizierung orogener Prozesse am Beispiel der Varisziden." Doctoral thesis, 2000. http://hdl.handle.net/11858/00-1735-0000-0006-B226-4.
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