Deep abiotic weathering of pyrite

Xin Gu, Peter J. Heaney, Fabio D.A.Aarão Reis, Susan L. Brantley

Research output: Contribution to journalArticlepeer-review

Abstract

Pyrite is a ubiquitous iron sulfide mineral that is oxidized by trace oxygen. The mineral has been largely absent from global sediments since the rise in oxygen concentration in Earth's early atmosphere. We analyzed weathering in shale, the most common rock exposed at Earth's surface, with chemical and microscopic analysis. By looking across scales from 10-9 to 102 meters, we determined the factors that control pyrite oxidation. Under the atmosphere today, pyrite oxidation is rate-limited by diffusion of oxygen to the grain surface and regulated by large-scale erosion and clast-scale fracturing. We determined that neither iron- nor sulfur-oxidizing microorganisms control global pyrite weathering fluxes despite their ability to catalyze the reaction. This multiscale picture emphasizes that fracturing and erosion are as important as atmospheric oxygen in limiting pyrite reactivity over Earth's history.

Original languageEnglish (US)
Article numbereabb8092
JournalScience
Volume370
Issue number6515
DOIs
StatePublished - Oct 23 2020

All Science Journal Classification (ASJC) codes

  • General

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