Iron silicate inclusions discovered in Archean cherts signal a major difference in early Earth biogeochemistry that is not yet understood. We perform laboratory experiments in an anoxic glovebox to synthesize similar iron-silicates under various plausible conditions for the 2.5 Ga ocean. These experiments will help us constrain the aqueous geochemistry of the iron-silicate producing ancient ocean, including the silica and ferrous iron activity, pH, and pO2 levels, as well as constrain the metabolic activities of ancient life.
Relevant publications:
Zhou A, Templeton AS, Johnson JE, (2024) Dissolved silica affects the bulk iron redox state and recrystallization of minerals generated by photoferrotrophy in a simulated Archean ocean, Geobiology 22 (1): e12587. doi: 10.1111/gbi.12587.
Hinz IL, Rossi L, Ma C, Johnson JE (2023), Simulated Diagenesis of the Iron-Silica Precipitates in Banded Iron Formations, American Mineralogist 108 (9): 1732–1753. doi: 10.2138/am-2022-8758.
Nims C, Johnson JE (2022) Exploring the secondary mineral products generated by microbial iron respiration in Archean ocean simulations, Geobiology 20: 743-763. doi: 10.1111/gbi.12523.
Hinz I, Nims C, Theuer S, Templeton AS, Johnson JE (2021) Ferric Iron Triggers Greenalite Formation in Simulated Archean Seawater, Geology. doi: 10.1130/G48495.1
Johnson JE, Muhling JR, Cosmidis J, Rasmussen B, Templeton AS (2018) Low-Fe(III) Greenalite Was a Primary Mineral From Neoarchean Oceans, Geophysical Research Letters, doi: 10.1002/2017GL076311.
