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Phytoplankton contributions to the trace-element composition of Precambrian banded iron formations

Kurt O. Konhauser, Leslie J. Robbins, Daniel S. Alessi, Shannon L. Flynn, Murray K. Gingras, Raul E. Martinez, Andreas Kappler, Elizabeth D. Swanner, Yi-Liang Li, Sean A. Crowe, Noah J. Planavsky, Christopher T. Reinhard and Stefan V. Lalonde
Phytoplankton contributions to the trace-element composition of Precambrian banded iron formations
Geological Society of America Bulletin (December 2017) 130 (5-6): 941-951


Banded iron formations are economically important sedimentary deposits in Earth's Precambrian rock record, consisting of alternating iron-rich (hematite, magnetite, and siderite) and silicate/carbonate (quartz, clay-like minerals, dolomite, and ankerite) layers. Based on chemical analyses from banded iron formation units of the 2.48 Ga Dales Gorge Member of the Hamersley Group in Western Australia, it has been previously suggested that most, if not all, of the iron in banded iron formations could have been oxidized by anoxygenic phototrophic bacteria (photoferrotrophs) at cell densities considerably less than those found in modern iron-rich aqueous environments. However, oxygen-producing phytoplankton may have also been capable of supplying the necessary oxidizing power. Here, we revisit the question of the anoxygenic and oxygenic phytoplankton populations necessary to account for banded iron formation deposition and quantify the amount of selected trace elements (P, Mn, Co, Ni, Cu, Zn, Mo, Cd) that could have been associated with their biomass. Using an expanded geochemical data set for the Dales Gorge Member as an example, we find that with turnover times comparable to those seen in modern ecosystems, the same phytoplankton populations required to form banded iron formations could have supplied the entirety of trace elements found in this iron-rich deposit. Further, spurred by the similarities between banded iron formation and anoxygenic phytoplankton trace-element stoichiometries, we suggest that much of the trace-element inventory preserved in the banded iron formation was at some point biologically assimilated in the water column, released from degrading photoferrotrophic biomass at the seafloor and in the sediment pile, and ultimately fixed in the iron-rich sediment in approximately stoichiometric proportions by near-quantitative adsorption to ferrihydrite. Our observations suggest that, as today, phytoplankton and the recycling of their biomass exerted control over the trace-element composition of ancient seawater and sediment.

ISSN: 0016-7606
EISSN: 1943-2674
Serial Title: Geological Society of America Bulletin
Serial Volume: 130
Serial Issue: 5-6
Title: Phytoplankton contributions to the trace-element composition of Precambrian banded iron formations
Affiliation: University of Alberta, Department of Earth and Atmospheric Sciences, Edmonton, AB, Canada
Pages: 941-951
Published: 20171220
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 110
Accession Number: 2018-022457
Categories: Geochemistry of rocks, soils, and sedimentsSedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2017376
Illustration Description: illus. incl. 1 table
S35°00'00" - S14°00'00", E113°00'00" - E129°00'00"
Secondary Affiliation: Albert-Ludwigs-Universitaet Freiburg, DEU, GermanyUniversity of Tubingen, DEU, GermanyIowa State University, USA, United StatesUniversity of Hong Kong, CHN, ChinaUniversity of British Columbia, CAN, CanadaYale University, USA, United StatesGeorgia Institute of Technology, USA, United StatesEuropean Institute for Marine Studies, FRA, France
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201812
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