Revisiting shallow glauconite factories: intertwined fates of glauconite and iron

Glauconite is an authigenic green mineral which has been studied extensively because its conditions of formation make it possible to evaluate certain parameters of the sedimentary environments where it is found. The most widespread view is that glauconite forms very slowly from a clay precursor, in...

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Main Author: Tribovillard, Nicolas
Format: Article
Language:English
Published: Académie des sciences 2024-11-01
Series:Comptes Rendus. Géoscience
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Online Access:https://comptes-rendus.academie-sciences.fr/geoscience/articles/10.5802/crgeos.274/
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author Tribovillard, Nicolas
author_facet Tribovillard, Nicolas
author_sort Tribovillard, Nicolas
collection DOAJ
description Glauconite is an authigenic green mineral which has been studied extensively because its conditions of formation make it possible to evaluate certain parameters of the sedimentary environments where it is found. The most widespread view is that glauconite forms very slowly from a clay precursor, in environments where low sedimentation rates allow prolonged contact over time between the authigenic mineral and seawater. The latter is seen as the source of some of the chemical elements necessary for the authigenic formation of this phyllosilicate, in particular iron (Fe). Typically, for relatively shallow environments, the distal portion of continental shelves is considered the most suitable formation environment. This review article makes it possible to broaden the spectrum of environments favorable to the growth of glauconite, by identifying environments that experience very shallow deposition depths and relatively high sedimentation rates. These situations are well illustrated by the Jurassic and Cretaceous deposits of the Boulonnais coast (Pas de Calais Strait, between the English Channel and the North Sea). In particular, certain sedimentary deposits show that glauconite could have grown during very early diagenesis. It therefore appears that glauconite can form in relatively varied environments, provided that two main conditions are met: the presence of an abundance of reactive iron and weakly reducing redox conditions. The emphasis of this paper is set on contrasted situations where various sources of iron are involved in the presence of glauconite. Last, abundant-pyrite accumulations imply large supplies of iron for their formation and, as the same time, represent a considerable iron sink with regard to the marine environment.
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spelling doaj-art-17e2acfe1e164b46b46cbacc32ff35b72025-02-07T10:41:12ZengAcadémie des sciencesComptes Rendus. Géoscience1778-70252024-11-01356G113915510.5802/crgeos.27410.5802/crgeos.274Revisiting shallow glauconite factories: intertwined fates of glauconite and ironTribovillard, Nicolas0https://orcid.org/0000-0003-3493-5579Université de Lille, UMR 8187 LOG – Laboratoire d’Océanologie et de Géosciences, Univ. Lille, CNRS, Univ. Littoral Côte d’Opale, IRD, 59000 Lille, FranceGlauconite is an authigenic green mineral which has been studied extensively because its conditions of formation make it possible to evaluate certain parameters of the sedimentary environments where it is found. The most widespread view is that glauconite forms very slowly from a clay precursor, in environments where low sedimentation rates allow prolonged contact over time between the authigenic mineral and seawater. The latter is seen as the source of some of the chemical elements necessary for the authigenic formation of this phyllosilicate, in particular iron (Fe). Typically, for relatively shallow environments, the distal portion of continental shelves is considered the most suitable formation environment. This review article makes it possible to broaden the spectrum of environments favorable to the growth of glauconite, by identifying environments that experience very shallow deposition depths and relatively high sedimentation rates. These situations are well illustrated by the Jurassic and Cretaceous deposits of the Boulonnais coast (Pas de Calais Strait, between the English Channel and the North Sea). In particular, certain sedimentary deposits show that glauconite could have grown during very early diagenesis. It therefore appears that glauconite can form in relatively varied environments, provided that two main conditions are met: the presence of an abundance of reactive iron and weakly reducing redox conditions. The emphasis of this paper is set on contrasted situations where various sources of iron are involved in the presence of glauconite. Last, abundant-pyrite accumulations imply large supplies of iron for their formation and, as the same time, represent a considerable iron sink with regard to the marine environment.https://comptes-rendus.academie-sciences.fr/geoscience/articles/10.5802/crgeos.274/Boulonnais areaJurassicCretaceousChalkCold seepsGreensands
spellingShingle Tribovillard, Nicolas
Revisiting shallow glauconite factories: intertwined fates of glauconite and iron
Comptes Rendus. Géoscience
Boulonnais area
Jurassic
Cretaceous
Chalk
Cold seeps
Greensands
title Revisiting shallow glauconite factories: intertwined fates of glauconite and iron
title_full Revisiting shallow glauconite factories: intertwined fates of glauconite and iron
title_fullStr Revisiting shallow glauconite factories: intertwined fates of glauconite and iron
title_full_unstemmed Revisiting shallow glauconite factories: intertwined fates of glauconite and iron
title_short Revisiting shallow glauconite factories: intertwined fates of glauconite and iron
title_sort revisiting shallow glauconite factories intertwined fates of glauconite and iron
topic Boulonnais area
Jurassic
Cretaceous
Chalk
Cold seeps
Greensands
url https://comptes-rendus.academie-sciences.fr/geoscience/articles/10.5802/crgeos.274/
work_keys_str_mv AT tribovillardnicolas revisitingshallowglauconitefactoriesintertwinedfatesofglauconiteandiron