The Serra da Graciosa A-type granites and syenites, southern Brazil. Part 1: regional setting and geological characterization

Gualda, G. A.; Vlach, Sílvio Roberto Farias

doi:10.1590/s0001-37652007000300006

Cited by 33 publications

(39 citation statements)

References 37 publications

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“…17b). Most samples gave temperatures close to 800 °C, a value significantly lower than temperature estimates obtained for similar plutons from the Graciosa Province (Gualda and Vlach 2007a) and A-type granites elsewhere (e.g. Poitrasson et al 1995, King et al 1997, King et al 2001, in the range 850 -900 °C.…”

Section: Crystallization Conditionsmentioning

confidence: 64%

“…The Quiriri Pluton has the largest area extent and comprises slightly peraluminous (1.05 < ASI < 1.20), subsolvus biotite ± hornblende syenogranites, as well as granite porphyries with higher magnetic susceptibilities, formed under relatively oxidizing conditions. Similar to other rocks of the aluminous association within the Graciosa Province Vlach 2007a, Vlach andGualda 2007), Quiriri granites have homogeneous compositions, with relatively lower fe# numbers and Fe 2 O 3 T /Al 2 O 3 molecular ratios and higher Ca and alkaline earth metals, and are characterized by relatively Caand Al-rich mafic mineral paragenesis defined by annitic biotite ± hornblende + titanite ± allanite + magnetite + ilmenite + fluorite (+ apatite + zircon). Consequently, biotite and hornblende show discrete chemical variations, contrary to what is observed in amphiboles and clinopyroxenes from the peralkaline Papanduva granites.…”

Section: Conclusion and Final Remarksmentioning

confidence: 85%

“…Altogether, geochemical signatures of the Quiriri Pluton are very akin with other peraluminous rocks from the aluminous association in the Graciosa Province (e.g. Vlach 2007a, Vlach andGualda 2007, cf . Fig.…”

Section: A-type Granites Of the Morro Redondo Complexmentioning

confidence: 88%

“…LITHOSTATIC PRESSURE AND TEMPERATURES Gualda and Vlach (2007a) emphasize that geological and petrographic evidences indicate that the emplacement of plutons from the Graciosa province are incompatible with confining pressures higher than ca. 200 MPa, an observation which is also in accordance with available gravimetric data (Hallinan et al 1993).…”

Section: Crystallization Conditionsmentioning

confidence: 99%

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Geology, petrography and geochemistry of the A-type granites from the Morro Redondo Complex (PR-SC), southern Brazil, Graciosa Province

Vilalva

Vlach

2014

An. Acad. Bras. Ciênc.

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The Morro Redondo Complex is one of the most important occurrences of the Graciosa A-type Province, southern Brazil. It consists of the Papanduva and Quiriri granitic plutons and a contemporaneous bimodal volcanic association. The Papanduva Pluton includes massive and deformed peralkaline alkali-feldspar granites with Na-Ca and Na-amphiboles and clinopyroxenes. The deformed types are the most evolved rocks in the province and carry rare 'agpaitic' minerals, some being described for the first time in granites from Brazil. The larger Quiriri Pluton comprises massive, slightly peraluminous, biotite syeno-and monzogranites with rare Ca-amphibole. Biotite compositions are relatively homogeneous, whereas sodic amphiboles and clinopyroxenes show increasing Na and Fe 3+ evolving paths. The Morro Redondo granites are ferroan, with high SiO 2 , alkalis and HFSE contents; the peralkaline types registering the highest fe#. LILE and HFSE abundances increase with the agpaitic index and the most evolved are HHP granites, with radiogenic heat production up to 5.7 μWm -3. Geothermobarometric estimates indicate emplacement under low pressures (~100 MPa), at temperatures up to 850-800 °C, and relatively reduced (QFM) and oxidized (+1 < Δ QFM < +3) environments for the Papanduva and Quiriri Plutons, respectively. In both cases, melts evolved to relatively high oxidation states upon crystallization progress.

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Section: Crystallization Conditionsmentioning

confidence: 64%

Section: Conclusion and Final Remarksmentioning

confidence: 85%

Section: A-type Granites Of the Morro Redondo Complexmentioning

confidence: 88%

Section: Crystallization Conditionsmentioning

confidence: 99%

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Geology, petrography and geochemistry of the A-type granites from the Morro Redondo Complex (PR-SC), southern Brazil, Graciosa Province

Vilalva

Vlach

2014

An. Acad. Bras. Ciênc.

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“…Após a secagem, as areias foram peneiradas para separação da fração 0,125 -0,062 mm, selecionada para análise de Salamuni et al (1999), Gualda & Vlach (2005).…”

Section: Métodos As Melhores Exposições Daunclassified

Proveniência de sedimentos da Bacia de Curitiba por estudos de minerais pesados

Machado

Fernandes

Góes

et al. 2012

Rev. bras. geociênc.

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DOI: 42(3): 563-572, setembro de 2012Arquivo digital disponível on-line no site www.sbgeo.org.br 563 ResumoA Bacia de Curitiba situa-se na porção Centro-sul do primeiro planalto paranaense. Inclui a cidade homônima e parte dos municípios da região metropolitana. É uma bacia neogênica alongada na direção ENE, que pertence ao Sistema de Riftes Cenozoicos do Sudeste do Brasil. Seu preenchimento sedimentar preservado estendese por 3.000 km 2 e compreende lamas, areias arcosianas e cascalhos da Formação Guabirotuba. Dentre as bacias que integram o Sistema de Riftes Cenozoicos do Sudeste do Brasil, a Bacia de Curitiba é a menos estudada em detalhes. Até o presente momento, não foram divulgadas pesquisas de tal assembleia acessória. Foram analisados minerais pesados transparentes, não micáceos e não magnéticos, de fração granulométrica 3 -4 φ (0,125 -0,062 mm), separados com uso de bromofórmio (d = 2,89 g/cm3 ) e ímã de mão. A determinação foi feita com montagens permanentes de grãos, com bálsamo do Canadá (n = 1,53), analisadas em microscópio petrográfico. Na assembleia mineralógica encontrada predominam grãos de zircão, além de epídoto, turmalina, cianita, rutilo e traços de sillimanita e granada. O zircão ocorre como grãos euédricos a subédricos incolores a subordinadamente róseos e metamícticos. O estudo de minerais pesados na Bacia de Curitiba sugere que, em direção ao centro da bacia, as quantidades de zircão tendem a diminuir, enquanto as quantidades de epídoto aumentam. Foram caracterizadas duas associações mineralógicas: a primeira, denominada Alto Zircão, possui quantidades de zircão entre 51 a 97%; a segunda foi denominada Alto Epídoto e tem quantidade máxima relativa de epídoto entre 31 a 53%. Essas diferenças nos valores de zircão e epídoto permitem inferir a possibilidade de mais de uma área-fonte para estes sedimentos. As principais tendências de paleocorrentes indicaram como potenciais rochas-fonte os granitos da Província Graciosa e os metamorfitos do Complexo Atuba. Ainda, não se pode descartar a possibilidade de segregação hidráulica. O zircão, por ser mais denso, tem tendência de não avançar tanto no transporte da bacia adentro quanto o epídoto que apresenta densidade menor. Conclui-se, portanto, que a proporção relativa entre estes dois minerais seria um bom traçador da dinâmica de transporte sedimentar na bacia. Palavras-chave: Bacia de Curitiba; minerais pesados; cenozoico. AbstractSediment provenance of the Curitiba basin by study of heavy minerals. Curitiba Basin is located in the South-central portion of the first plateau of Paraná. It includes the city of the same name and some towns of the metropolitan region. It is a neogean basin elongated towards ENE direction, which belongs to the Cenozoic Rift System in Southeast Brazil. Its maintained sedimentary fill extends over 3,000 km2 and includes sludge, arkosic sands, and gravels of Guabirotuba Formation. Among the basins that are part of the Cenozoic Rift System of Southeast Brazil, Curitiba Basin is the least studied in details. Until the pre...

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Eocene adakitic porphyries in the central‐northern Qiangtang Block, central Tibet: Partial melting of thickened lower crust and implications for initial surface uplifting of the plateau

Wang

Wyman

et al. 2017

JGR Solid Earth

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The time and mechanism of crustal thickening and initial surface uplift of the Tibetan Plateau remain highly controversial. Here we report on zircon U‐Pb age, and mineral, element, and Sr‐Nd isotope composition data for Eocene adakitic porphyries in the Laorite Co area of central‐northern Qiangtang Block, central Tibet. Laser ablation‐inductively coupled plasma‐mass spectrometry zircon U‐Pb age dating shows that the porphyries were generated at 42–41 Ma. All samples display adakitic geochemical characteristics, such as high SiO2 and Al2O3, and low Y and Yb contents, and high Sr/Y and La/Yb ratios with positive Sr and negligible Eu anomalies and Nb‐Ta depletion. They also have low magnesium number (Mg #) (16–45) and high K2O (4.0–4.6 wt %) values, as well as high (87Sr/86Sr)i (0.7076–0.7080) and low εNd(t) (−5.9 to −4.4) values. These adakitic rocks were most probably generated by partial melting of thickened lower crust in the stability field of garnet, amphibole, and rutile but with relatively minor plagioclase. Moreover, such a crustal thickening process beneath this block likely occurred no later than the middle Eocene and was most probably caused by the southward subduction of the Songpan‐Ganzi Block in the early Cenozoic. In addition, the occurrences of exposed adakitic porphyries unambiguously indicate that exhumation process occurred after their formation. Thus, these ~42 Ma adakitic porphyries indicate the occurrence of significant exhumation since 42 Ma. Integrated with the thermochronological and paleoelevation data, we suggest that the initial surface uplift of the Qiangtang Block, triggered by crustal thickening, was underway by the middle Eocene (~42 Ma).

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The Serra da Graciosa A-type granites and syenites, southern Brazil. Part 1: regional setting and geological characterization

Cited by 33 publications

References 37 publications

Geology, petrography and geochemistry of the A-type granites from the Morro Redondo Complex (PR-SC), southern Brazil, Graciosa Province

Geology, petrography and geochemistry of the A-type granites from the Morro Redondo Complex (PR-SC), southern Brazil, Graciosa Province

Proveniência de sedimentos da Bacia de Curitiba por estudos de minerais pesados

Eocene adakitic porphyries in the central‐northern Qiangtang Block, central Tibet: Partial melting of thickened lower crust and implications for initial surface uplifting of the plateau

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