TY - JOUR
T1 - A key role for green rust in the Precambrian oceans and the genesis of iron formations
AU - Halevy, I.
AU - Alesker, M.
AU - Schuster, E. M.
AU - Popovitz-Biro, R.
AU - Feldman, Y.
N1 - European Research Council [337183]; Israeli Science Foundation [764/12] We thank N. Tosca for valuable comments. I.H. acknowledges funding from a European Research Council Starting Grant 337183, and an Israeli Science Foundation Grant 764/12. I. H. is the incumbent of the Anna and Maurice Boukstein Career Development Chair at the Weizmann Institute of Science. Electron microscopy was carried out at the Moskowitz Center for Nano and Bio-Nano Imaging.
PY - 2017/2
Y1 - 2017/2
N2 - Iron formations deposited in marine settings during the Precambrian represent large sinks of iron and silica, and have been used to reconstruct environmental conditions at the time of their formation. However, the observed mineralogy in iron formations, which consists of iron oxides, silicates, carbonates and sulfides, is generally thought to have arisen from diagenesis of one or more mineral precursors. Ferric iron hydroxides and ferrous carbonates and silicates have been identified as prime candidates. Here we investigate the potential role of green rust, a ferrous-ferric hydroxy salt, in the genesis of iron formations. Our laboratory experiments show that green rust readily forms in early seawater-analogue solutions, as predicted by thermodynamic calculations, and that it ages into minerals observed in iron formations. Dynamic models of the iron cycle further indicate that green rust would have precipitated near the iron redoxcline, and it is expected that when the green rust sank it transformed into stable phases within the water column and sediments. We suggest, therefore, that the precipitation and transformation of green rust was a key process in the iron cycle, and that the interaction of green rust with various elements should be included in any consideration of Precambrian biogeochemical cycles.
AB - Iron formations deposited in marine settings during the Precambrian represent large sinks of iron and silica, and have been used to reconstruct environmental conditions at the time of their formation. However, the observed mineralogy in iron formations, which consists of iron oxides, silicates, carbonates and sulfides, is generally thought to have arisen from diagenesis of one or more mineral precursors. Ferric iron hydroxides and ferrous carbonates and silicates have been identified as prime candidates. Here we investigate the potential role of green rust, a ferrous-ferric hydroxy salt, in the genesis of iron formations. Our laboratory experiments show that green rust readily forms in early seawater-analogue solutions, as predicted by thermodynamic calculations, and that it ages into minerals observed in iron formations. Dynamic models of the iron cycle further indicate that green rust would have precipitated near the iron redoxcline, and it is expected that when the green rust sank it transformed into stable phases within the water column and sediments. We suggest, therefore, that the precipitation and transformation of green rust was a key process in the iron cycle, and that the interaction of green rust with various elements should be included in any consideration of Precambrian biogeochemical cycles.
UR - http://www.scopus.com/inward/record.url?scp=85027830752&partnerID=8YFLogxK
U2 - https://doi.org/10.1038/NGEO2878
DO - https://doi.org/10.1038/NGEO2878
M3 - مقالة
SN - 1752-0894
VL - 10
SP - 135
EP - 139
JO - Nature Geoscience
JF - Nature Geoscience
IS - 2
ER -