Episodic negative anomalies of cerium at the depositional onset of the 2.65-Ga Itabira iron formation, Quadrilátero Ferrífero of Minas Gerais, Brazil
2016; Elsevier BV; Volume: 276; Linguagem: Inglês
10.1016/j.precamres.2016.01.031
ISSN1872-7433
AutoresAlexandre Raphael Cabral, Bernd Lehmann, Antônio Augusto Seabra Gomes, Jan Pašava,
Tópico(s)Geological and Geochemical Analysis
ResumoMagnetite bands in sericitic phyllite of the Batatal Formation mark the transition to the overlying 2.65-Ga Itabira iron formation, or Cauê Itabirite, in the Quadrilátero Ferrífero of Minas Gerais, Brazil. The magnetite bands have low (non-crustal) Th/U ratios, suprachondritic Y/Ho ratios and sporadic anomalies of Ce that are characterised as truly negative. The data point to mild oxygenation of sea water at the depositional onset of the Itabira iron formation some 200 Ma before the Great Oxidation Event.
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