@article{4e98386aeb8d41f8b87ea90b15e91a81,
title = "Low-Fe(III) Greenalite Was a Primary Mineral From Neoarchean Oceans",
abstract = "Banded iron formations (BIFs) represent chemical precipitation from Earth's early oceans and therefore contain insights into ancient marine biogeochemistry. However, BIFs have undergone multiple episodes of alteration, making it difficult to assess the primary mineral assemblage. Nanoscale mineral inclusions from 2.5 billion year old BIFs and ferruginous cherts provide new evidence that iron silicates were primary minerals deposited from the Neoarchean ocean, contrasting sharply with current models for BIF inception. Here we used multiscale imaging and spectroscopic techniques to characterize the best preserved examples of these inclusions. Our integrated results demonstrate that these early minerals were low-Fe(III) greenalite. We present potential pathways in which low-Fe(III) greenalite could have formed through changes in saturation state and/or iron oxidation and reduction. Future constraints for ancient ocean chemistry and early life's activities should include low-Fe(III) greenalite as a primary mineral in the Neoarchean ocean.",
author = "Johnson, {Jena E.} and Muhling, {Janet R.} and Julie Cosmidis and Birger Rasmussen and Templeton, {Alexis S.}",
note = "Funding Information: Supplemental data and results can be found in the supporting information, and data used to generate figures can be found on the Deep Blue online repository (doi: 10.7302/Z2XS5SMK). We appreciate the contributions of Eric Ellison on Fe XANES acquisition and analysis and Tyler Kane for performing bulk XRD measurements and assisting with XRD analyses using JADE software. We additionally are grateful to S. Guggenheim for providing a greenalite standard and to George Rossman for contributing a standard for cronstedtite and for his mineralogical consultations, as well as the helpful feedback from Nicholas Tosca and an anonymous reviewer. Samuel Webb and Ryan Davis greatly helped with our data acquisition from SSRL and Jian Wang provided calibration and assistance for our STXM measurements at CLS. We additionally thank Franck Bourdelle who kindly helped us produce the Fe3+/FeTOTAL maps. We acknowledge the Department of Mines and Petroleum, Western Australia, for access to drill hole ABDP9 and the Council for Geoscience (South Africa) for access to drill hole GKF. FIB and TEM analyses were performed at the Centre for Microscopy, Characterisation and Analysis, the University of Western Australia, a node of the Australian Microscopy and Microanalysis Research Facility funded from university and government sources. This research was funded by the Agouron Institute (Postdoctoral Fellowship) to J.E.J and the Rock-Powered Life NASA Astrobiology Institute (Cooperative Agreement NNA15BB02A). Portions of the research described in this paper was performed at the Canadian Light Source, which is supported by the Canada Foundation for Innovation, Natural Sciences and Engineering Research Council of Canada, the University of Saskatchewan, the Government of Saskatchewan, Western Economic Diversification Canada, the National Research Council Canada, and the Canadian Institutes of Health Research. Portions of this research were carried out at the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under contract DE-AC02-76SF00515. The SSRL Structural Molecular Biology Program is supported by the DOE Office of Biological and Environmental Research and by the National Institute of Health, National Institute of General Medical Sciences (including P41GM103393). Publisher Copyright: {\textcopyright}2018. American Geophysical Union. All Rights Reserved.",
year = "2018",
month = apr,
day = "16",
doi = "10.1002/2017GL076311",
language = "English (US)",
volume = "45",
pages = "3182--3192",
journal = "Geophysical Research Letters",
issn = "0094-8276",
publisher = "American Geophysical Union",
number = "7",
}