Trace elements and isotope geochemistry (C, O, Fe, Cr) of the Cauê iron formation, Quadrilátero Ferrífero, Brazil: Evidence for widespread microbial dissimilatory iron reduction at the Archean/Paleoproterozoic transition

The Banded Iron Formation (BIFs) of the Cauê Formation, Quadrilátero Ferrífero, Brazil, are part of the great volume of BIFs deposited worldwide around 2.45 Ga. Samples of carbonate (ankerite/dolomite) BIF from this unit were collected from a drill core ca. 600 m deep in the Alegria region. Geochemical data suggest low clastic contamination (Y/Ho = 37.7) and seawater-like signatures, with positive La and Y anomalies, no true Ce anomalies and...