Deciphering the impact of diagenesis overprint on negative delta C-13 excursions using rock magnetism: Case study of Ediacaran carbonates, Yangjiaping section, South China | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Deciphering the impact of diagenesis overprint on negative delta C-13 excursions using rock magnetism: Case study of Ediacaran carbonates, Yangjiaping section, South China

Type de publication:

Journal Article

Source:

Earth and Planetary Science Letters, Volume 351, p.281-294 (2012)

ISBN:

0012-821X

Mots-clés:

UMR 7154 ; Géochimie des isotopes stables ; Paléomagnétisme

Résumé:

Rock magnetism is used here to investigate the genesis of one of the puzzling negative carbon isotopic excursions of the Neoproterozoic in the Yangtze platform (South China). A detailed characterization of the magnetic mineralogy, which includes low-temperature and high-field magnetometry and classical magnetic measurement (ARM, IRM, susceptibility), was therefore performed along upper Doushantuo and lower Dengying Formations outcropping in the Yangjiaping section. The derived magnetic parameters show variations that can be interpreted as variations in magnetic grains size and in oxide contents. They show that the magnetic content is significantly reduced in samples presenting negative δ13Ccalcite values. We interpret this as a result of magnetite dissolution and secondary carbonate precipitation during early diagenesis bacterial sulfate reduction.