Iron isotope constraints on the Archean and Paleoproterozoic ocean redox state.
The response of the ocean redox state to the rise of atmospheric oxygen about 2.3 billion years ago (Ga) is a matter of controversy. Here we provide iron isotope evidence that the change in the ocean iron cycle occurred at the same time as the change in the atmospheric redox state. Variable and negative iron isotope values in pyrites older than about 2.3 Ga suggest that an iron-rich global ocean was strongly affected by the deposition of iron oxides. Between 2.3 and 1.8 Ga, positive iron isotope values of pyrite likely reflect an increase in the precipitation of iron sulfides relative to iron oxides in a redox stratified ocean.
Rouxel
Olivier J
OJ
Marine Chemistry and Geochemistry Department, Geomicrobiology Group, Woods Hole Oceanographic Institution, Mail Stop 8, Woods Hole, MA 02543, USA. orouxel@whoi.edu
Bekker
Andrey
A
Edwards
Katrina J
KJ
D001272:Atmosphere; D011232:Chemical Precipitation; D005290:Ferric Compounds / Q000032:analysis; D019015:Geologic Sediments / Q000737:chemistry*; D007501:Iron / Q000032:analysis*; D007503:Iron Isotopes / Q000032:analysis*; D009792:Oceans and Seas; D010084:Oxidation-Reduction; D010100:Oxygen; D012623:Seawater; D013440:Sulfides / Q000032:analysis*; D013995:Time
D005290:Ferric Compounds; D007503:Iron Isotopes; D013440:Sulfides; C011342:pyrite; C000499:ferric oxide; D007501:Iron; D010100:Oxygen