REE patterns as a tool for recognition of diagenetic beds: a case from the Lower Devonian Upper Gaspé Limestones, Gaspé Peninsula, Québec

Authors

  • Denis Lavoie Centre Gioscientifique de Quibec, Geological Survey of Canada
  • Mario Bergeron Centre Gioscientifique de Quibec, INRS-Gioressources

DOI:

https://doi.org/10.4138/1989

Abstract

Analyses of rare earth elements (REE), major elements, insoluble residue content and mineralogy were performed on carbonate and siliciclastic samples from the Early Devonian Upper Gaspé Limestones in eastern Gaspé Peninsula. Siliciclastic rocks are richer in REE than coeval mechanically deposited carbonates. A positive relationship between the absolute amount of REE and the content of aluminosilicate is clear for most samples. Even if poor in aluminosilicate, diagenetic carbonate concretions are the richest in REE. The concretions also show a significant negative Europium anomaly. Mineralogical, major element and stable isotope data show that calcite cementation resulting in the concretions was rapid and completed before reaching the methanogenic zone. Diagenetic conditions were responsible for remobilization of the REE from host detrital material and for raising the REE content of the concretions. The REE pattern is a potential tool for recognition of diagenetic beds produced in various geochemical environments. RÉSUMÉ Une étude du contenu en terres rares (TR), de la géochimie des éléments majeurs et de la teneur et minéralogie des résidus insolubles fut menée sur des échantillons de carbonates et silicoclastites provenant des Calcaires supérieurs de Gaspé (Dévonien précoce) de Test de la Gaspésie. Les silicoclastites sont plus riches en TR que les carbonates contemporains. Une relation positive entre la teneur en TR et le contenu en aluminosilicates s'observe dans la majorité des échantillons. Bien que pauvres en aluminosilicates, les concretions diagénéliques ont donné les valeurs les plus élevées en TR. Ces concretions sont également caractérisées par une importanle anomalie négative en europium. Les données minérialogiques, les éléments majeurs et les isotopes stables montrent que la cimentation de calcite a l'origine des concrétions fut rapide et complété avant d'atteindre la zone de méthanogenèse. Les conditions diagénétiques furent responsables de la remobilisation des TR provenant des sédiments détriliques encaissants et de l’augmentation du contenu en TR dans les concrétions. Le patron des TR est ainsi vu comme un outil potentiel pour reconnaitre les lits diagénétiques originant d'environnements géochimiques variés. [Traduit par la rédaction]

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Published

1993-03-01

How to Cite

Lavoie, D., & Bergeron, M. (1993). REE patterns as a tool for recognition of diagenetic beds: a case from the Lower Devonian Upper Gaspé Limestones, Gaspé Peninsula, Québec. Atlantic Geoscience, 29(1). https://doi.org/10.4138/1989

Issue

Vol. 29 No. 1 (1993)

Section

Articles

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