Primary hematite in Neoarchean to Paleoproterozoic oceans
2015-01-22

Research Article| May 01, 2015 Primary hematite in Neoarchean to Paleoproterozoic oceans Si Sun; Si Sun 1Department of Earth Sciences, University of Hong Kong, Hong Kong, China Search for other works by this author on: GSW Google Scholar Kurt O. Konhauser; Kurt O. Konhauser 2Department of Atmospheric and Earth Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada Search for other works by this author on: GSW Google Scholar Andreas Kappler; Andreas Kappler 3Geomicrobiology Group, Center for Applied Geosciences, University of Tübingen, Sigwartstrasse 10 72076, Tübingen, Germany Search for other works by this author on: GSW Google Scholar Yi-Liang Li Yi-Liang Li † 1Department of Earth Sciences, University of Hong Kong, Hong Kong, China †yiliang@hku.hk. Search for other works by this author on: GSW Google Scholar Author and Article Information Si Sun 1Department of Earth Sciences, University of Hong Kong, Hong Kong, China Kurt O. Konhauser 2Department of Atmospheric and Earth Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada Andreas Kappler 3Geomicrobiology Group, Center for Applied Geosciences, University of Tübingen, Sigwartstrasse 10 72076, Tübingen, Germany Yi-Liang Li † 1Department of Earth Sciences, University of Hong Kong, Hong Kong, China †yiliang@hku.hk. Publisher: Geological Society of America Received: 24 Apr 2014 Revision Received: 18 Nov 2014 Accepted: 19 Dec 2014 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2015 Geological Society of America GSA Bulletin (2015) 127 (5-6): 850–861. https://doi.org/10.1130/B31122.1 Article history Received: 24 Apr 2014 Revision Received: 18 Nov 2014 Accepted: 19 Dec 2014 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Si Sun, Kurt O. Konhauser, Andreas Kappler, Yi-Liang Li; Primary hematite in Neoarchean to Paleoproterozoic oceans. GSA Bulletin 2015;; 127 (5-6): 850–861. doi: https://doi.org/10.1130/B31122.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Banded iron formations (BIFs) are iron- and silica-rich chemical sedimentary rocks formed throughout the Archean and Paleoproterozoic Eras. The presence of hematite (Fe2O3) and magnetite (Fe3O4) in BIFs has led to the widespread assumption that Fe(II) oxidation must have occurred in the ancient oceans via either a biological or chemical mechanism. However, it is unclear whether the ferric iron now present in BIF represents the original ferric oxyhydroxide [e.g., ferrihydrite, Fe(OH)3] precipitated in the water column, or if it is the result of later-stage circulation of oxidizing fluids through the sediment pile. In this study, we conducted high-resolution microscopic investigations on BIF from the 2728 Ma Abitibi greenstone belt located in the Superior Province of the Canadian Shield and the 2460 Ma Kuruman Iron Formation in South Africa to ascertain the timing and paragenesis of the hematite. Three types of hematite are identified by high-resolution electron microscopic characterization and selected area electron diffraction: (1) 3–5 nm ultrafine hematite particles in the iron oxide–rich bands (H1); (2) submicrometer subhedral to euhedral hematite crystals randomly distributed in the chert matrix of transitional zones between iron oxide– and chert-rich bands (H2); and (3) needle-like, radial and fibrous hematite that replaced stilpnomelane or carbonates and is distributed along fractures or layer boundaries (H3). We interpret the first two types as primary minerals dehydrated from precursor ferric oxyhydroxides. H1 remains ultrafine in size, while H2 has undergone an Ostwald coarsening process facilitated by internal fluids produced during amorphous silica to quartz transformation. H3 is a later-stage mineral formed by external fluid-mediated replacement of iron silicates or carbonates. These results indicate that a significant fraction of the hematite in the BIF originated from ferric oxyhydroxide precursors. Importantly, this implies that photosynthetic Fe(II) oxidation, by either a direct or indirect biological mechanism, did exist in seawaters from which some BIF material was deposited. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.