Abstract:Fe isotope compositions, major and rare earth elements (REE) of Archaean banded iron formations from Anshan_Benxi area, Liaoning Province have been studied. The average bulk compositions of banded iron formations (BIFs) are rich in total Fe and SiO2, but the Al2O3 and TiO2 contents are very low. These chemical features show that they are chemical sediments devoid of detrital input. REE concentrations in BIFs are very low; the shale-normalized REE+Y patterns display distinct positive anomalies of Eu, Y, and La, and depletion of light REE relative to heavy REE. This demonstrates that the BIFs are the products of chemical sedimentation from paleo_seawater with significant input of volcanic hydrothermal fluids. The Fe isotope compositions of the bulk samples are not only enriched in heavy Fe isotopes relative to IRMM-014, but also strongly correlated with Eu/Eu*, providing direct evidence for the first time that the Fe in the BIFs originate from hydrothermal fluids