The microbially driven formation of siderite in salt marsh sediments

Lin, Chin Yik and Turchyn, Alexandra V. and Krylov, Alexey and Antler, Gilad (2020) The microbially driven formation of siderite in salt marsh sediments. Geobiology, 18 (2). pp. 207-224. ISSN 1472-4677 DOI https://doi.org/10.1111/gbi.12371

[img] Text
gbi.12371.pdf - Published Version
Available under License Creative Commons Attribution.

Download (2MB)
[img] Text
gbi12371-sup-0001-MaterialsA-F.docx - Supplemental Material

Download (2MB)
Official URL: https://doi.org/10.1111/gbi.12371

Abstract

We employ complementary field and laboratory‐based incubation techniques to explore the geochemical environment where siderite concretions are actively forming and growing, including solid‐phase analysis of the sediment, concretion, and associated pore fluid chemistry. These recently formed siderite concretions allow us to explore the geochemical processes that lead to the formation of this less common carbonate mineral. We conclude that there are two phases of siderite concretion growth within the sediment, as there are distinct changes in the carbon isotopic composition and mineralogy across the concretions. Incubated sediment samples allow us to explore the stability of siderite over a range of geochemical conditions. Our incubation results suggest that the formation of siderite can be very rapid (about two weeks or within 400 hr) when there is a substantial source of iron, either from microbial iron reduction or from steel material; however, a source of dissolved iron is not enough to induce siderite precipitation. We suggest that sufficient alkalinity is the limiting factor for siderite precipitation during microbial iron reduction while the lack of dissolved iron is the limiting factor for siderite formation if microbial sulfate reduction is the dominant microbial metabolism. We show that siderite can form via heated transformation (at temperature 100°C for 48 hr) of calcite and monohydrocalcite seeds in the presence of dissolved iron. Our transformation experiments suggest that the formation of siderite is promoted when carbonate seeds are present.

Item Type: Article
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
07 - Gold Open Access
12 - PhD
Journal or Publication Title: Geobiology
Volume: 18
Page Range: pp. 207-224
Identification Number: https://doi.org/10.1111/gbi.12371
Depositing User: Sarah Humbert
Date Deposited: 28 Feb 2020 14:27
Last Modified: 28 Feb 2020 14:27
URI: http://eprints.esc.cam.ac.uk/id/eprint/4643

Actions (login required)

View Item View Item

About cookies