Please use this identifier to cite or link to this item:
Title: Tourmaline composition and boron isotopes record lateritic weathering during the great oxidation event.
Authors: Cabral, Alexandre Raphael
Ferreira, Tiago Henrique de
Lana, Cristiano de Carvalho
Castro, Marco Paulo de
Queiroga, Gláucia Nascimento
Issue Date: 2020
Citation: CABRAL, A. R. et al.Tourmaline composition and boron isotopes record lateritic weathering during the great oxidation event. Terra Nova, v. 33, p. 46-55, fev./jul. 2020.Disponível em: <>. Acesso em: 19 fev. 2021.
Abstract: Identifying evidence of oxidative weathering in the geological record is essential to trace the evolution of Earth's atmosphere oxygenation. Metamorphosed residues of lateritic weathering have been identified as two rock types in the 2.1-Ga-old Cercadinho Formation, Piracicaba Group, Quadrilátero Ferrífero of Minas Gerais. One is tourmaline–hematite–sillimanite–kyanite quartzite; the other is rutile–tourmaline–hematite–muscovite phyllite. Both rocks have abundant tourmaline with δ11B values between about −17‰ and −13‰. The Cercadinho tourmaline is roughly parallel to the povondraite–“oxy-dravite” join of meta-evaporitic tourmaline, in its more aluminous segment, offset to higher contents of iron. These compositional and isotopic characteristics of the Cercadinho tourmaline indicate that continental evaporitic brines interacted with aluminium- and iron-rich residues of lateritic weathering. The abundance of disseminated tourmaline, a mineral poorly reported from palaeosols worldwide, implies a boron-rich brine overprint on the lateritic profile before the onset of metamorphism, reflecting a climatic change from humid to arid conditions in a continental setting. The recognition of lateritic weathering in the Cercadinho Formation contributes to the amount of evidence for increased levels of atmospheric oxygen between 2.22 and 2.06 Ga ago.
ISSN: 1365-3121
Appears in Collections:DEGEO - Artigos publicados em periódicos

Files in This Item:
File Description SizeFormat 
  Restricted Access
1,58 MBAdobe PDFView/Open

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.