Chemostratigraphy of the Carajás banded iron formation, Brazil : a record of Neoarchean Ocean chemistry
- Martins, Pedro Luiz Gomes
- Toledo, Catarina Laboure Bemfica
- Silva, Adalene M.
- Chemale Junior, Farid
- Arche, Corey
- Assis, Luciano M. de
DOIAbstract
One of the most important occurrences of banded iron formation (BIF) worldwide is situated in the Carajás Mineral Province, southeastern Amazonian Craton. The BIFs are jaspilites and are hosted in the Neoarchean ( 2.74 Ga) volcano-sedimentary sequence of the Grão-Pará Group. They are mostly composed of cm-thick intercalations of hematite, jasper, and chert. Their primary textures and structures are still preserved, which make them an ideal archive to evaluate the paleomarine environment. Low abundance of Al2O3 (<1.0 wt%) and HFSE (<1 ppm) for most BIF samples indicate an essentially detritus-free depositional environment. Overall, the rare earth elements and yttrium (REY) patterns show a weak positive lanthanum (La) anomaly, and a pronounce...
Add to ORKG