title: Widespread iron-rich conditions in the mid-Proterozoic ocean.
abstract: The chemical composition of the ocean changed markedly with the oxidation of the Earth's surface, and this process has profoundly influenced the evolutionary and ecological history of life. The early Earth was characterized by a reducing ocean-atmosphere system, whereas the Phanerozoic eon (less than 542 million years ago) is known for a stable and oxygenated biosphere conducive to the radiation of animals. The redox characteristics of surface environments during Earth's middle age (1.8-1 billion years ago) are less well known, but it is generally assumed that the mid-Proterozoic was home to a globally sulphidic (euxinic) deep ocean. Here we present iron data from a suite of mid-Proterozoic marine mudstones. Contrary to the popular model, our results indicate that ferruginous (anoxic and Fe(2+)-rich) conditions were both spatially and temporally extensive across diverse palaeogeographic settings in the mid-Proterozoic ocean, inviting new models for the temporal distribution of iron formations and the availability of bioessential trace elements during a critical window for eukaryotic evolution.
authors: Department of Earth Sciences, University of California, Riverside, California 92521, USA.
authors: Noah J
authors: NJ
authors: Planavsky
authors: Peter
authors: P
authors: McGoldrick
authors: Clinton T
authors: CT
authors: Scott
authors: Chao
authors: C
authors: Li
authors: Christopher T
authors: CT
authors: Reinhard
authors: Amy E
authors: AE
authors: Kelly
authors: Xuelei
authors: X
authors: Chu
authors: Andrey
authors: A
authors: Bekker
authors: Gordon D
authors: GD
authors: Love
authors: Timothy W
authors: TW
authors: Lyons
mesh_terms: D005075:Biological Evolution; D019015:Geologic Sediments / Q000737:chemistry; D049690:History, Ancient; D007501:Iron / Q000032:analysis* / Q000737:chemistry; D009792:Oceans and Seas; D012623:Seawater / Q000737:chemistry*; D013455:Sulfur / Q000032:analysis / Q000737:chemistry; D013460:Sulfur Isotopes; D013997:Time Factors
chemical_list: D013460:Sulfur Isotopes; D013455:Sulfur; D007501:Iron