Anomalous δ¹⁵N values in the Neoarchean associated with an abundant supply of hydrothermal ammonium

verfasst von

Ashley N. Martin, Eva E. Stüeken, Michelle M. Gehringer, Monika Markowska, Hubert Vonhof, Stefan Weyer, Axel Hofmann

Abstract

Unusually high δ¹⁵N values in the Neoarchean sedimentary record in the time period from 2.8 to 2.6 Ga, termed the Nitrogen Isotope Event (NIE), might be explained by aerobic N cycling prior to the Great Oxidation Event (GOE). Here we report strongly positive δ¹⁵N values up to +42.5 ‰ in ~2.75 – 2.73 Ga shallow-marine carbonates from Zimbabwe. As the corresponding deeper-marine shales exhibit negative δ¹⁵N values that are explained by partial biological uptake from a large ammonium reservoir, we interpret our data to have resulted from hydrothermal upwelling of ¹⁵N-rich ammonium into shallow, partially oxic waters, consistent with uranium isotope variations. This work shows that anomalous N isotope signatures at the onset of the NIE temporally correlate with extensive volcanic and hydrothermal activity both locally and globally, which may have stimulated primary production and spurred biological innovation in the lead-up to the GOE.

Organisationseinheit(en)

Institut für Erdsystemwissenschaften
Abteilung Mineralogie
AG Geochemie

Externe Organisation(en)

Northumbria University
University of St. Andrews
Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau (RPTU)
Max-Planck-Institut für Chemie (Otto-Hahn-Institut)
University of Johannesburg

Typ

Artikel

Journal

Nature Communications

Band

16

ISSN

2041-1723

Publikationsdatum

22.02.2025

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Allgemeine Chemie, Allgemeine Biochemie, Genetik und Molekularbiologie, Allgemeine Physik und Astronomie

Ziele für nachhaltige Entwicklung

SDG 14 – Lebensraum Wasser

Elektronische Version(en)

https://doi.org/10.1038/s41467-025-57091-3 (Zugang: Offen)