Assinatura isotópica de Sr e Nd do magmatismo cálcio-alcalino de alto-K na Faixa Ribeira central: o exemplo do Granito São Pedro em Lumiar, RJ

Mendes, Júlio Cézar; Medeiros, Sílvia Regina de; Chaves, Eduardo Amorim

doi:10.25249/0375-7536.2011413408419

Cited by 8 publications

(7 citation statements)

References 22 publications

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“…The samples from Santos Basin present lower radiogenic Nd and higher radiogenic Pb values, thus indicating a Pre-Cambrian source, as Mantovanelli et al (2018) stated. Nevertheless, the values obtained for Pb isotopes differ significantly from those reported by the literature for the Precambrian metasediments and granites of the southeastern Brazilian coast (Ragatky et al, 2000;Moraes et al, 2004;Mendes et al, 2011). A possible explanation for this discrepancy lies in the fact that the input of sediments from the adjacent coast is hampered by the presence of the Serra do Mar mountain chain, which limits the development of expressive drainage basins in the area.…”

Section: Discussioncontrasting

confidence: 54%

New insights of the influence of ocean circulation on the sedimentary distribution in the Southwestern Atlantic margin (23° S to 55° S) based on Nd and Pb isotopic fingerprinting

Mahiques¹,

Violante²,

Franco-Fraguas³

et al. 2021

Preprint

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Abstract. In this work, we provide an extensive inventory of Pb and Nd radiogenic isotopes in surface sediments from the Southwestern Atlantic margin, aiming to interpret the role played by ocean circulation in sediment distribution. There are latitudinal trends for Pb and Nd isotopes, reflecting the different current systems acting on the margin. The utilization of sediment fingerprinting allowed us to associate the isotopic signatures to the main oceanographic forcings in the area. We recognized differences between the Nd and Pb sources for the sediments to the Argentinean shelf, carried by the Subantarctic Shelf Water, and slope, transported by deeper flows. Sediments from Antarctica extend up to the Uruguayan margin, carried by the Upper- and Lower Circumpolar Deep Water. Our data confirm that, for shelf and intermediate (up to 1,200 m water depth) areas, the transfer of sediments from the Argentinean margin to the North of 35° S is limited by the Subtropical Shelf Front and the recirculated Antarctic Intermediate Water. On the southern Brazilian margin, it is possible to recognize the northward influence of the Río de la Plata sediments carried by the Plata Plume Water. This influence is limited by the southward flow of waters transported by the Brazil Current. Finally, we propose that the Subtropical Shelf Front and the Santos Bifurcation act as boundaries of geochemical provinces in the area. Finally, a qualitative model of sediment sources and transport is provided for the Southwestern Atlantic margin.

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Section: Discussioncontrasting

confidence: 54%

New insights of the influence of ocean circulation on the sedimentary distribution in the Southwestern Atlantic margin (23° S to 55° S) based on Nd and Pb isotopic fingerprinting

Mahiques¹,

Violante²,

Franco-Fraguas³

et al. 2021

Preprint

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“…In order to characterize the provenance of the sediments from the cores, we present the first summarized data of Nd radiogenic isotope system from multiple sources: Do Carmo Fonseca (1994), Reis Neto (1994), Siga (1995), Campanha and Sadowski (1999), André et al (2009), Ragatky et al (2000), Tupinambá et al (2012), Dias Neto (2001), Dos Prazeres Filho et al 2003, Heilbron et al (2004), Passarelli et al (2004), Silva (2006), Junior et al (2007), Valladares et al (2008), Bento dos Santos et al 2011, Mendes et al (2011), and Dantas et al (2017), as well as a Nd distribution map for the study area. The compilation has included isotopic data from marine and river sediments related to the evaluated continental rocks: (A) ε Nd(0) data of superficial sediments from the Rio de La Plata estuary and Argentinian shelf (Basile et al, 1997;de Mahiques et al, 2008); (B) Nd data associated with eroded rocks of Coastal Domain of the Ribeira belt; (C) Nd radiogenic isotope signatures of Paraíba do Sul River suspended load (Roig et al, 2005).…”

Section: Methodsmentioning

confidence: 99%

Characterization of Nd Radiogenic Isotope Signatures in Sediments From the Southwestern Atlantic Margin

Mantovanelli

Tassinari²,

Mahiques

et al. 2018

Front. Earth Sci.

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Based on radiogenic isotope systems of neodymium [Epsilon Neodymium-ε Nd(0), 143 Nd/ 144 Nd, 147 Sm/ 144 Nd, and Sm-Nd Depleted Mantle Model ages-T DM ] from current and previous data of continental rocks and associated sediments, this work provides the provenance of Holocene sediments from the Southwestern Atlantic Margin. The isotopic variability reported along the cores 7616 and 7620 are related to paleoceanographic and paleoclimatic changes. Further, we display the first Nd radiogenic isotope system distribution map of the study area. The map is the result of the principal component and clustering analyses of data compiled from the Ribeira belt, Luís Alves craton, and Paraná basin rocks. Differences in Nd isotopic signatures allowed the distinction between the sediment sources of the cores. The Core 7616 exhibits ε Nd(0) average value of −10.5, T DM = 1.4 Ga and 143 Nd/ 144 Nd = 0.512103, while the Core 7620 shows ε Nd(0) average value of −17.5, T DM = 1.8 Ga and 143 Nd/ 144 Nd = 0.51177. The relative more radiogenic Nd ratios from the Core 7616 are associated to the contribution of sediments from the Paraná basin, nevertheless less radiogenic values are observed along the Core 7616 between ∼2,000 and 1,800 cal. yr BP. We have attributed the lower Nd ratios, recorded during this interval, to the decreasing influence from the Rio de la Plata estuary in the Core 7616. Remarkable less radiogenic Nd ratios are also recorded in the Core 7620 during the late Holocene. The intensification of the NE winds and the South America Summer Monsoon (SASM) enhanced the terrigenous input from the Paraíba do Sul River and southwards sediment transport by the Brazil Current (BC), providing higher contribution of less radiogenic metasediments from the Paraíba do Sul geotectonic domain to the Core 7620.

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“…At the Central Ribeira Belt, other smaller post-collisional bodies are known, such as the Cajú granite (454 ± 5 Ma; Bongiolo et al 2016); the São Pedro de Lumiar granite (~490 Ma; Mendes et al 2011); the Mambucaba granite (492 ± 15; Machado et al 1996) and the MC granite, focus of this study.…”

Section: B Amentioning

confidence: 99%

Geochemistry, Sm-Nd isotopes and SHRIMP U-Pb geochronology of the Morro do Coco Granite (RJ, Brazil): another piece of the post-collisional magmatism of the Ribeira Belt

et al. 2019

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The Morro do Coco granite (MC) is a post-collisional intrusive body that was emplaced at Ribeira Belt, in the Cambro-Ordovician, succeeding the final stages of the Gondwana supercontinent amalgamation. This unit requires more studies, contrasting with similar best investigated occurrences of the central Ribeira Belt. This work presents a detailed investigation of such unit using petrography, Inductively Coupled Plasma (ICP), X-Ray Fluorescence (XRF) whole-rock geochemistry, U-Pb (SHRIMP) geochronology and Sm-Nd isotopes. The rock is a nearly undeformed syenogranite, geochemically classified as a high-K calc-alkaline magnesian, with metaluminous to slightly peraluminous affinity. Strongly light rare earth elements (LREE)-enriched patterns with significant negative Eu anomalies, typical of post-collisional granites, are identified. Similarly to other post-collisional granites of the central Ribeira Belt, U-Pb zircon data provide crystallization age of 496 ± 3 Ma. Sm-Nd isotopic data suggest crustal magma source as indicated by εNd (496) of-9, 143 Nd/ 144 Nd ratios between 0.511747 and 0.511752 and Mesoproterozoic TDM ages of 1.3 Ga. Based on its geochemical characteristics, morphology and geochronology, this unit is considered here as a member of Nova Friburgo Suite. Geochronological data defined three pulses of magmatism in this part of the orogen during the Cambro-Ordovician (515, 490 and 460 Ma).

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Assinatura isotópica de Sr e Nd do magmatismo cálcio-alcalino de alto-K na Faixa Ribeira central: o exemplo do Granito São Pedro em Lumiar, RJ

Cited by 8 publications

References 22 publications

New insights of the influence of ocean circulation on the sedimentary distribution in the Southwestern Atlantic margin (23° S to 55° S) based on Nd and Pb isotopic fingerprinting

New insights of the influence of ocean circulation on the sedimentary distribution in the Southwestern Atlantic margin (23° S to 55° S) based on Nd and Pb isotopic fingerprinting

Characterization of Nd Radiogenic Isotope Signatures in Sediments From the Southwestern Atlantic Margin

Geochemistry, Sm-Nd isotopes and SHRIMP U-Pb geochronology of the Morro do Coco Granite (RJ, Brazil): another piece of the post-collisional magmatism of the Ribeira Belt

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