Iron-bearing carbonate minerals such as siderite (FeCO
3) have formed throughout the Earth's history. However, its formational mechanism, in particular pathway (s) of Fe incorporation into carbonate crystals, have not been well constrained. Recent studies have demonstrated that large fractionations of stable Fe isotopes occur during biogeochemical redox cycling (Fe
3+ ⇄ Fe
2+). Therefore, Fe isotope (bio) geochemistry is potentially useful, when applied to the Fe-carbonate system, to understand the (bio) geochemical behavior of Fe during Fe-carbonate formation in sediment diagenesis and to constrain its depositional environment. In this contribution, the current progress of Fe isotope geochemistry for the Fe-carbonate system is summarized using examples from experimental studies and from field studies of Cretaceous, Jurassic, and Archean carbonate rocks. Future studies of Fe isotope geochemistry of carbonate rocks are proposed, with new hypotheses for the Neoproterozoic "Snowball Earth" and stromatolites. Experimental determination of essential isotope fractionation factors between different Fe-bearing carbonate minerals and between Fe-bearing minerals and Fe-bearing fluids are needed for better interpretation of field data. Despite its infancy, Fe isotope biogeochemistry will be a promising new tool for the studies of the Fe-carbonate system.
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