Editing Banded iron formation (section)

====Source of reduced iron====
[[File:BlackSmoker.jpg|alt=|thumb|upright=1.5|Hydrothermal vents were one important source for the reduced iron that was later oxidized to form banded iron formations.]]
There must be an ample source of reduced iron that can circulate freely into the deposition basin.<ref name="trendall-blockley-2004"/> Plausible sources of iron include [[hydrothermal vents]] along mid-ocean ridges, windblown dust, rivers, glacial ice, and [[seepage]] from continental margins.<ref name="cox-etal-2013"/>

The importance of various sources of reduced iron has likely changed dramatically across geologic time. This is reflected in the division of BIFs into Algoma and Lake Superior-type deposits.<ref name="Nadoll_2014">{{cite journal|last1 = Nadoll |first1=P. |last2=Angerer |first2=T. |last3=Mauk |first3=J.L. |last4=French |first4=D. |last5=Walshe |first5=J |title=The chemistry of hydrothermal magnetite: A review|journal=Ore Geology Reviews|volume=61|pages=1–32|doi=10.1016/j.oregeorev.2013.12.013|year=2014|bibcode=2014OGRv...61....1N }}</ref><ref name="Zhu_2014">{{Cite journal|last1 = Zhu |first1=X.Q. |last2=Tang |first2=H.S. |last3=Sun |first3=X.H. |title=Genesis of banded iron formations: A series of experimental simulations|journal=Ore Geology Reviews|volume=63|pages=465–469|doi=10.1016/j.oregeorev.2014.03.009|year=2014|bibcode=2014OGRv...63..465Z }}</ref><ref name="Li_2015">{{cite journal |last1 = Li |first1=L.X. |last2=Li |first2=H.M. |last3=Xu |first3=Y.X. |last4=Chen |first4=J. |last5=Yao |first5=T. |last6=Zhang |first6=L.F. |last7=Yang |first7=X.Q. |last8=Liu |first8=M.J. |title=Zircon growth and ages of migmatites in the Algoma-type BIF-hosted iron deposits in Qianxi Group from eastern Hebei Province, China: Timing of BIF deposition and anatexis|journal=Journal of Asian Earth Sciences|volume=113|pages=1017–1034|doi=10.1016/j.jseaes.2015.02.007|bibcode=2015JAESc.113.1017L|year=2015}}</ref> Algoma-type BIFs formed primarily in the Archean. These older BIFs tend to show a positive [[europium anomaly]] consistent with a [[Hydrothermal vent|hydrothermal]] source of iron.<ref name="condie-2015"/>  By contrast, Lake Superior-type banded iron formations primarily formed during the [[Paleoproterozoic]] era, and lack the europium anomalies of the older Algoma-type BIFs, suggesting a much greater input of iron weathered from continents.<ref name="klein-2005"/><ref name="Li-etal-2015">{{cite journal |last1=Li |first1=Weiqiang |last2=Beard |first2=Brian L. |last3=Johnson |first3=Clark M. |title=Biologically recycled continental iron is a major component in banded iron formations |journal=Proceedings of the National Academy of Sciences |date=7 July 2015 |volume=112 |issue=27 |pages=8193–8198 |doi=10.1073/pnas.1505515112|pmid=26109570 |pmc=4500253 |bibcode=2015PNAS..112.8193L |doi-access=free }}</ref><ref name="condie-2015"/>