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Formation pathways of Precambrian sedimentary pyrite: Insights from in situ Fe isotopes by Juliette Dupeyron; Marie-Noëlle Decraene; Johanna Marin-Carbonne; Vincent Busigny is a Earth and Planetary Sciences article available to read on EtoBox.

What is Formation pathways of Precambrian sedimentary pyrite: Insights from in situ Fe isotopes about?

Iron isotope compositions (expressed as δ 56 Fe) in sedimentary pyrite have been widely used as tracers of redox and chemical evolution of the ocean through geological time. Previous studies mostly built on the mechanical extraction of sulfides from bulk rock samples, and focused on visible macroscopic pyrites, which may introduce a sampling bias. In situ analyses of micropyrite grains can provide new insights into the processes of pyrite formation and their time evolution. Here, we compile ca. 2000 in situ iron isotope compositions of Archean to Paleoproterozoic sedimentary pyrite, from previous literature as well as new data. Contrasting with bulk analyses, micropyrite displays a large and constant range of δ 56 Fe values, from -4 to +4‰, through time. Micropyrite δ 56 Fe values are not significantly influenced by metamorphic grade. A bimodal distribution of positive versus negative δ 56 Fe values can be attributed to two different processes of pyrite formation, Fe (oxyhydr)oxide sulfidation, versus kinetic and possibly microbially mediated pyrite precipitation. These processes are tightly related to rock lithology and thus to sedimentary conditions, and have existed since 3.8 Ga

Who reads Formation pathways of Precambrian sedimentary pyrite: Insights from in situ Fe isotopes?

Author

Juliette Dupeyron; Marie-Noëlle Decraene; Johanna Marin-Carbonne; Vincent Busigny

Publisher

Elsevier BV

Published

2023

Language

EN

Field

Earth and Planetary Sciences (Physical Sciences)