Evolução crustal do limite oriental da Faixa Paraguai : significado tectônico da granitogênese de high Ba-Sr e suas rochas hospedeiras

Tese (doutorado) — Universidade de Brasília, Instituto de Geociências, Programa de Pós-Graduação em Geologia, 2021.As faixas móveis mais recentes da Plataforma Sul-Americana correspondem a regiões que registram intensa atividade tectônica, formadas durante a Orogenia Brasiliana. A Província Tocantins é considerada um mosaico composto pelas Faixas móveis Paraguai, Araguaia e Brasilia, geradas entre os crátons Amazônico e São Francisco. Esta tese de doutorado busca contribuir na compreensão da evolução geotectônica da região oriental da Faixa Paraguai a partir do estudo de granitóides e rochas metassedimentares encaixantes. A região de estudo é localizada quase nas imediações do contato com o Lineamento Transbrasiliano (LTB), que faz limite com o Arco Magmático Arenópolis, Faixa Brasília. A área de interesse é constituída por sequência supracrustal metamorfisada em fácies xisto verde e por corpos graníticos pouco estudados, tipicamente associados ao magmatismo neoproterozoico da Faixa Paraguai. Parte das rochas estudadas apresentam deformação superimposta transcorrente, relacionada evolução do Sistema Direcional do Lineamento Transbrasiliano. Os granitóides estudados compreendem duas suítes que cristalizaram com aproximadamente 40 Ma de diferença entre si. Ambas as suítes apresentam elevados teores de Ba (~1430 ppm), Sr (~800 ppm), K2O (~4 wt%), LREE e LILE. Os valores negativos de εNd(T) (-6,32 e -6,65), associados a conteúdos elevados de elementos incompatíveis, indicam evolução a partir da fusão parcial do magma derivado do manto, que foi previamente metassomatizado por fluidos vindos da placa subductante. Foram obtidas idades de cristalização de 557±5,7 Ma e 554±2,9 Ma para a suite mais antiga, que apresenta caráter cálcio-alcalino e alto K. Esta suíte evoluiu de magma apinítico com alto conteúdo de Cr, V e Ni, derivado do manto, para magma contemporâneo granodioritíco a partir de cristalização fracionada acompanhada de pequena contaminação crustal. A suite mais nova, de 515±3,6 Ma, é representada por monzogranitos isotópicos de alto K e concentração elevada de alguns HFSE, mostrando afinidade álcali-cálcica. O modelo petrológico proposto para as duas suítes baseia-se no mecanismo de slab break-off e posterior delaminação litosférica após 40 Ma. O estudo de proveniência sedimentar foi aplicado nas rochas metassedimentares encaixantes dos granitoides. A utilização de zircão detrítico com a aplicação do método U-Pb permitiu estabelecer espectro de idades distribuídas desde o fim do Ediacarano até o Arqueano, sendo ~60% dos grãos analisados são derivados de fontes ediacarano-criogenianas. A idade máxima de deposição da bacia é definida em ca. 594 Ma, limitada pelos pico principal de zircões mais jovens. O caráter sin-orogênico da bacia é definido pelo fato de que mais de 50% dos grãos apresentam idades próximas da idade máxima de sedimentação da bacia. O maior pico de idades U-Pb de zircão é registrado em torno de 620 Ma, indicando um evento de sedimentação sin-colisional relacionado à atividade de um arco magmático contemporâneo à deposição. O desenvolvimento dessa margem ativa teria acontecido após ca. 620 Ma e se encerrado em 594 Ma com a deposição da bacia. A idade 40Ar-39Ar de 536±4 Ma obtida para o metamorfismo das rochas encaixantes indica a continuação da temperatura de aproximadamente 400 oC até o Cambriano. Pode-se sugerir também a presença de alguns plutons que não afloram na área que causou o aquecimento da área neste período. A taxa rápida de 25oC/Myr indica a taxa de resfriamento do pluton granodiorítico, associação às falhas transcorrentes relacionadas ao Lineamento Transbrasiliano. Os dados geoquímicos e geocronológicos U-Pb do magmatismo e de zircão detrítico, associado ao contexto tectônico e metamórfico, indicam que a evolução da porção central do Gondwana Oriental ultrapassou os 600 Ma e, possivelmente, um oceano mais jovem foi consumido, o Oceano Clymene.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).The youngest mobile belts of the South-American Platform correspond to regions that record intense tectonic activity and were formed during the Brasiliano Orogeny. The Tocantins Province is a mosaic composed of three mobile belts located between the Amazonian and São Francisco cratons. This Ph.D. thesis presents the advance of the studies regarding the geotectonic evolution of the eastern region of the Paraguay Belt, located almost on its limit with the Arenópolis Magmatic Arc of the Brasília Belt. The study area is composed of a supracrustal sequence metamorphosed to the greenschist facies and granitic bodies associated with the Neoproterozoic magmatism of the Paraguay Belt. Superimposed deformation was produced by transcurrent faults related to the Transbrasiliano Lineament (LTB). The granitoids of the study area belong to two suites that crystallized with an approximately 40 Ma age difference from one another. Both suites present high Ba (~1430 ppm), Sr (~800 ppm), K2O (~4 wt%), LREE and LILE contents. Negative εNd(T) values (-6.32 and -6.65 respectively) associated with high incompatible-element contents indicate magmatic evolution from partial melting of a previously metasomatized mantle by fluids coming from a subducting plate. Crystallization ages of 557 ± 5.7 Ma and 554 ± 2.9 Ma were obtained for the older, high-K, calc-alkaline suite. This suite evolved from a mantle-derived, appinitic magma with high Cr, V, and Ni contents to a coeval granodioritic magma via fractional crystallization accompanied by minor crustal contamination. The younger suite of 515 ± 3.6 Ma of age is represented by high-K monzogranites with high concentrations of some HFSE, indicating alkali-calcic affinity. The petrologic model proposed for both hybrid suites is based on the slab break-off mechanism followed by lithospheric delamination after 40 Ma. Sedimentary provenance of the metasedimentary rocks that host the granitoid bodies was investigated. Detrital zircon U-Pb geochronology helped establish an age spectrum from the beginning of the Cambrian to the Archean, in which ~60% of the zircon grains derived from Ediacaran-Cryogenian sources. maximum deposition age is defined at ca. 594 Ma, constrained by the main peak youngest zircon grains. The syn-orogenic character of the sedimentary basin is inferred by the fact that the ages obtained for more than 50% of the grains are close to the maximum sedimentation age obtained for the basin. The highest zircon U-Pb age peak is recorded around 620 Ma, indicating a syn- collisional sedimentation event related to the activity of a magmatic arc coeval to deposition. The development of this active margin may have taken place after ca. 620 Ma and ended at ca. 594 Ma. The 40Ar-39Ar age of 536 ± 1.83 Ma obtained for the metamorphism of the host rocks indicates the maintenance of a temperature of approximately 400 oC until the Cambrian or may indicate the presence of plutons that not cropped out, yielding the heating in the area. A 25oC/Myr cooling rate is estimated for the granodioritic magma – the fast magma emplacement takes place possibly associated with transcurrent faults related to the Transbrasiliano Lineament. The assembly of the data presented here highlight the fact that the study area was a tectonically active region from the late Ediacaran to the beginning of the Cambrian. The geochronological U-Pb data from detrital zircon and magmatic rocks, associated to the tectonic and metamorphic context, indicate that the evolution of the central portion of West Gondwana has overtaken 600 Ma. Possibly, a younger ocean was consumed for generation of this rocks, the Clymene Ocean

Sustentabilidade Aplicada ao Design

O presente artigo tem por objetivo identificar as formas nas quais o conceito de sustentabilidade é e pode ser aplicado ao design na prática. Para fim de fundamentação teórica foram realizadas pesquisas bibliográficas de teóricos estudiosos da sustentabilidade e seus conceitos, e do design e sua prática, a princípio sem maior aprofundamento, o que se mostrou preciso por conta de lacunas de informação encontradas no decorrer das pesquisas, evidenciando a necessidade de estudos de caso posteriores, para chegar-se a uma conclusão de que a falta de informação na área da aplicabilidade da sustentabilidade, performa grande influência em aplicabilidade na área do design

The molecular structure of the borate mineral inderite Mg(H4B3O7)(OH)-5H2O - a vibrational spectroscopic study.

We have undertaken a study of the mineral inderite Mg(H4B3O7)(OH)_5H2O a hydrated hydroxy borate mineral of magnesium using scanning electron microscopy, thermogravimetry and vibrational spectroscopic techniques. The structure consists of ?B3O3?OH?5_2_ soroborate groups and Mg(OH)2(H2O)4 octahedra interconnected into discrete molecules by the sharing of two OH groups. Thermogravimetry shows a mass loss of 47.2% at 137.5 _C, proving the mineral is thermally unstable. Raman bands at 954, 1047 and 1116 cm_1 are assigned to the trigonal symmetric stretching mode. The two bands at 880 and 916 cm_1 are attributed to the symmetric stretching mode of the tetrahedral boron. Both the Raman and infrared spectra of inderite show complexity. Raman bands are observed at 3052, 3233, 3330, 3392 attributed to water stretching vibrations and 3459 cm_1 with sharper bands at 3459, 3530 and 3562 cm_1 assigned to OH stretching vibrations. Vibrational spectroscopy is used to assess the molecular structure of inderite

Menarche age association with anthropometric measures in school

Objetivo: O presente estudo teve o objetivo de verificar a idade da menarca e associa-la a dados antropométricos de escolares. Materiais e método: Estudo transversal no qual participaram 44 escolares de nove a 14 anos pertencentes a uma escola privada no município de Maringá, Paraná, Brasil. Foi utilizado um questionário contendo dados como idade e o “status quo”, identificação da data da menarca e avaliação do peso, estatura e índice de massa corporal (IMC). Os dados foram analisados por meio dos testes Shapiro-Wilk, t de student independente, e Exato de Fisher (p<0,05). Resultados: As 27 escolares que já tinham sofrido a menarca apresentaram a média de idade de 11,07±1,14. As demais (n = 17) ainda não haviam apresentado o primeiro ciclo menstrual. O valor do IMC destas 27 participantes foi estaticamente superior às demais (p=0,00428). Conclusão: As meninas apresentaram a menarca por volta dos 13 anos e a partir do momento que ocorre a menarca existe uma tendência de o IMC sofrer um aumento.Objective: The present study aimed to verify the age of menarche and to associate it with anthropometric data of schoolchildren. Materials and method: Cross-sectional study in which 44 students from nine to 14 years old belonging to a private school in the city of Maringá, Paraná, Brazil participated. A questionnaire was used containing data such as age and the “status quo”, identification of the date of menarche and assessment of weight, height, and body mass index (BMI). Data were analyzed using the Shapiro-Wilk, independent student t, and Fisher’s exact tests (p <0.05). Results: The 27 students who had already suffered menarche had a mean age of 11.07 ± 1.14. The others (n = 17) had not yet had their first menstrual cycle. The BMI value of these 27 participants was statically higher than the others (p = 0.00428). Conclusion: Girls presented menarche at around 13 years of age and from the moment menarche occurs there is a tendency for BMI to increase

Vibrational spectroscopic characterization of the phosphate mineral kulanite Ba(Fe2+,Mn2+,Mg)2(Al,Fe3+)2(PO4)3(OH)3

The mineral kulanite BaFe2Al2(PO4)3(OH)3, a barium iron aluminum phosphate, has been studied by using a combination of electron microscopy and vibrational spectroscopy. Scanning electron microscopy with EDX shows the mineral is homogenous with no other phases present. The Raman spectrum is dominated by an intense band at 1022 cm−1 assigned to the PO43-ν1 symmetric stretching mode. Low intensity Raman bands at 1076, 1110, 1146, 1182 cm−1 are attributed to the PO43-ν3 antisymmetric stretching vibrations. The infrared spectrum shows a complex spectral profile with overlapping bands. Multiple phosphate bending vibrations supports the concept of a reduction in symmetry of the phosphate anion. Raman spectrum at 3211, 3513 and 3533 cm−1 are assigned to the stretching vibrations of the OH units. Vibrational spectroscopy enables aspects on the molecular structure of kulanite to be assessed

Infrared and Raman spectroscopic characterisation of the sulphate mineral creedite – Ca3Al2SO4(F,OH)·2H2O – and in comparison with the alums

The mineral creedite is a fluorinated hydroxy hydrated sulphate of aluminium and calcium of formula Ca3Al2SO4(F,OH)·2H2O. The mineral has been studied by a combination of electron probe analysis to determine the molecular formula of the mineral and the structure assessed by vibrational spectroscopy. The spectroscopy of creedite may be compared with that of the alums. The Raman spectrum of creedite is characterised by an intense sharp band at 986 cm−1 assigned to the View the MathML source ν1 (Ag) symmetric stretching mode. Multiple bands of creedite in the antisymmetric stretching region support the concept of a reduction in symmetry of the sulphate anion. Multiple bands are also observed in the bending region with the three bands at 601, 629 and 663 cm−1 assigned to the View the MathML source ν4 (Ag) bending modes. The observation of multiple bands at 440, 457 and 483 cm−1 attributed to the View the MathML source ν2 (Bg) bending modes supports the concept that the symmetry of the sulphate is reduced by coordination to the water bonded to the Al3+ in the creedite structure. The splitting of the ν2, ν3 and ν4 modes is attributed to the reduction of symmetry of the SO4 and it is proposed that the sulphate coordinates to water in the hydrated aluminium in bidentate chelation

Vibrational spectroscopy of the phosphate mineral kovdorskite – Mg2PO4(OH)⋅3H2O

The mineral kovdorskite Mg2PO4(OH)�3H2O was studied by electron microscopy, thermal analysis and vibrational spectroscopy. A comparison of the vibrational spectroscopy of kovdorskite is made with other magnesium bearing phosphate minerals and compounds. Electron probe analysis proves the mineral is very pure. The Raman spectrum is characterized by a band at 965 cm�1 attributed to the PO3�\ud 4 m1 symmetric stretching mode. Raman bands at 1057 and 1089 cm�1 are attributed to the PO3�4 m3 antisymmetric\ud stretching modes. Raman bands at 412, 454 and 485 cm�1 are assigned to the PO3�4 m2 bending modes.\ud Raman bands at 536, 546 and 574 cm�1 are assigned to the PO3�4 m4 bending modes. The Raman spectrum in the OH stretching region is dominated by a very sharp intense band at 3681 cm�1 assigned to the stretching vibration of OH units. Infrared bands observed at 2762, 2977, 3204, 3275 and 3394 cm�1 are attributed to water stretching bands. Vibrational spectroscopy shows that no carbonate bands are\ud observed in the spectra; thus confirming the formula of the mineral as Mg2PO4(OH)�3H2O

The spectroscopic characterization of the sulphate mineral ettringite from Kuruman manganese deposits, South Africa

The mineral ettringite has been studied using a number of techniques, including XRD, SEM with EDX, thermogravimetry and vibrational spectroscopy. The mineral proved to be composed of 53% of ettringite and 47% of thaumasite in a solid solution. Thermogravimetry shows a mass loss of 46.2% up to 1000 °C. Raman spectroscopy identifies multiple sulphate symmetric stretching modes in line with the three sulphate crystallographically different sites. Raman spectroscopy also identifies a band at 1072 cm−1 attributed to a carbonate symmetric stretching mode, confirming the presence of thaumasite. The observation of multiple bands in the ν4 spectral region between 700 and 550 cm−1 offers evidence for the reduction in symmetry of the sulphate anion from Td to C2v or even lower symmetry. The Raman band at 3629 cm−1 is assigned to the OH unit stretching vibration and the broad feature at around 3487 cm−1 to water stretching bands. Vibrational spectroscopy enables an assessment of the molecular structure of natural ettringite to be made