Cretaceous carbonatites of the southeastern Brazilian Platform: a review

Gomes, Celso B.; Comin-Chiaramontí, P.; Azzone, Rogério Guitarrari; Ruberti, Excelso; Rojas, Gaston Eduardo Enrich

doi:10.1590/2317-4889201820170123

Cited by 21 publications

(2 citation statements)

References 124 publications

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“…and unradiogenic 143 Nd/ 144 Nd (<0.5122) of Polino and other ULUD carbonatites and calcite separates overlap the ULUD silicatic rocks. These values are far from the field of worldwide carbonatites ( 87 Sr/ 86 Sr <0.7065; 143 Nd/ 144 Nd > 0.5123; refs 47,85,86 ), questioning the interpretation of Polino calcite as a mantle carbonatitic component. The 87 Sr/ 86 Sr of Polino calcite and whole-rock carbonatite is also higher than that of local Calcare Massiccio limestone (<0.7075; ref.…”

Section: Carbonatite Melt-silicate Solid Vs Silicate Melt-carbonatitmentioning

confidence: 94%

Fuzzy petrology in the origin of carbonatitic/pseudocarbonatitic Ca-rich ultrabasic magma at Polino (central Italy)

Lustrino

Luciani

Stagno

2019

Sci Rep

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The small upper Pleistocene diatreme of Polino (central Italy) is known in literature as one of the few monticellite alvikites (volcanic Ca-carbonatite) worldwide. This outcrop belongs to the Umbria-Latium Ultra-alkaline District (ULUD), an area characterized by scattered and small-volume strongly SiO 2 -undersaturated ultrabasic igneous rocks located in the axial sector of the Apennine Mts. in central Italy. Petrographic and mineralogical evidences indicate that Polino olivine and phlogopite are liquidus phases rather than mantle xenocrysts as instead reported in literature. The presence of monticellite as rim of olivine phenocrysts and as groundmass phase indicates its late appearance in magma chambers at shallow depths, as demonstrated by experimental studies too. The absence of plagioclase and clinopyroxene along with the extremely MgO-rich composition of olivine (Fo 92–94 ) and phlogopite (average Mg# ~93) suggest for Polino magmas an origin from a carbonated H 2 O-bearing mantle source at depths at least of 90–100 km, in the magnesite stability field. In contrast with what reported in literature, the ultimate strongly ultrabasic Ca-rich whole-rock composition (~15–25 wt% SiO 2 , ~31–40 wt% CaO) and the abundant modal groundmass calcite are not pristine features of Polino magma. We propose that the observed mineral assemblage and whole-rock compositions result mostly from the assimilation of limestones by an ultrabasic melt at a depth of ~5 km. A reaction involving liquidus olivine + limestone producing monticellite + CO 2 vapour + calcite is at the base of the origin of the Polino pseudocarbonatitic igneous rocks.

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Section: Carbonatite Melt-silicate Solid Vs Silicate Melt-carbonatitmentioning

confidence: 94%

Fuzzy petrology in the origin of carbonatitic/pseudocarbonatitic Ca-rich ultrabasic magma at Polino (central Italy)

Lustrino

Luciani

Stagno

2019

Sci Rep

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“…Alkaline and/or carbonatite plugs and dykes occur widespread in Brazil, Paraguay, Bolivia and Uruguay of Paleozoic to Tertiary ages (Gomes et al, 2011). The Ponta Grossa alkaline province (Almeida, 1983, Riccomimi et al, 2005 is coeval with the tholeiitic rocks of the PGDS (e.g., Jacupinga Complex; Chmyz et al,2017).…”

Section: The Lower Cretaceous Dyke Swarmsmentioning

confidence: 99%

The magmatic rifting of Santos Basin: aeromagnetic mapping of dykes, terranes and marginal structures and the interplay between tectonism and volcanism

Ferreira

Stanton

Gordon

et al. 2022

Preprint

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Hydrochemistry and isotopic studies of carbonatite groundwater systems: the alkaline–carbonatite complex of Barreiro, southeastern Brazil

Raposo¹,

Pereira

2019

Environ Earth Sci

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Cretaceous carbonatites of the southeastern Brazilian Platform: a review

Abstract: This paper reviews general aspects of alkaline-carbonatitic rocks of Brazilian

Cited by 21 publications

References 124 publications

Fuzzy petrology in the origin of carbonatitic/pseudocarbonatitic Ca-rich ultrabasic magma at Polino (central Italy)

Fuzzy petrology in the origin of carbonatitic/pseudocarbonatitic Ca-rich ultrabasic magma at Polino (central Italy)

The magmatic rifting of Santos Basin: aeromagnetic mapping of dykes, terranes and marginal structures and the interplay between tectonism and volcanism

Hydrochemistry and isotopic studies of carbonatite groundwater systems: the alkaline–carbonatite complex of Barreiro, southeastern Brazil

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