Robbins, LJ, Swanner, ED, Lalonde, SV et al. (6 more authors) (2015) Limited Zn and Ni mobility during simulated iron formation diagenesis. Chemical Geology, 402. 30 - 39. ISSN 0009-2541
Abstract
Iron formations (IF) are iron- and silica-rich chemical precipitates that were deposited during the Precambrian. Several recent studies have demonstrated how the trace metal abundances in IF can be used as proxies for the bioavailability of trace metals in ancient seawater; with the ultimate goal being to understand first-order controls on the composition of the ancient biosphere. However, the utility of IF as proxies depends on the immobilization of trace metals during diagenesis. Here, we assess the mobility of Zn and Ni from ferric oxyhydroxides (ferrihydrite) in the absence and presence of organic matter (glucose) during simulated diagenesis (170 °C, 1.2 kbar); similar to what some Precambrian IF experienced. Quantitative concentration data, coupled with X-ray diffraction analysis and electron microprobe element mapping, demonstrate that both metals are relatively immobile during simulated diagenesis. Additionally, the mechanism for initial Ni sorption is examined using X-ray adsorption spectroscopy. For the initial sorption of trace elements in abiotic ferrihydrite experiments, 93.38% Zn and 65.95% Ni were initially sorbed. In experiments utilizing biogenic ferrihydrite, 97.03% of Zn and 93.38% of Ni were initially sorbed. Following the diagenetic capsule treatments, more than 99% of Zn and more than 91.9% of Ni were retained under the varied conditions considered here. Capsule experiments suggest the strong retention of Zn and Ni following the diagenesis of either abiotic or biogenic ferrihydrite. Overall, our results indicate that paleomarine Zn and Ni concentrations are likely to be faithfully recorded in well-preserved IF deposits.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2015 Elsevier B.V. All rights reserved. This is an author produced version of a paper published in Chemical Geology. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Iron formations; Zinc; Nickel; Diagenesis; Iron oxyhydroxides; Trace metal mobility |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Earth Surface Science Institute (ESSI) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 11 Aug 2015 10:51 |
Last Modified: | 11 Mar 2016 05:45 |
Published Version: | http://dx.doi.org/10.1016/j.chemgeo.2015.02.037 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.chemgeo.2015.02.037 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:86170 |