Open AccessRare-earth element content of carbonate minerals in sediment-hosted Pb-Zn deposits, southern Canadian Rocky Mountains
Author(s) -
George J. Simandl,
Rameses J. D’Souza,
Suzanne Paradis,
Jody Spence
Publication year - 2022
Language(s) - English
Resource type - Reports
DOI - 10.4095/328001
Subject(s) - geology , carbonate , geochemistry , rare earth element , diagenesis , metallogeny , carbonate rock , back arc basin , carbonate minerals , oil shale , seawater , mineralogy , pyrite , sedimentary rock , calcite , rare earth , subduction , paleontology , sphalerite , materials science , metallurgy , tectonics , oceanography
Paleozoic platform carbonate rocks of the Rocky Mountains host Mississippi Valley-type (MVT), magnesite, barite, and REE-barite-fluorite deposits. Farther west, platform carbonate rocks of the Kootenay Arc host MVT and fracture-controlled replacement (FCR)deposits. This is the first systematic LA-ICP-MS study of carbonates in MVT and FCR deposits. We investigated seven MVT deposits in the Rocky Mountains, and five MVT deposits in the Kootenay Arc. None of the post-Archean Australian shale (PAAS)-normalized REE profiles show light REE (LREE) depletionand strong negative Ce anomalies characteristic of modern seawater: some profiles are nearly flat; others show depletion in LREE similar to seawater but without negative Ce anomalies; others are middle REE enriched. Carbonates with a strong positive Eu anomaly precipitated from or interacted withdifferent fluids than carbonates with flatter profiles without a strong positive Eu anomaly. REE signatures reflect crystallization conditions of primary carbonates, and crystallization and re-equilibration conditions of carbonates with ambient fluids during diagenesis, deep burial, and/ormetamorphic recrystallization. Chemical evolution of fluids along their migration path, fluid-to-rock ratio, fluid acidity, redox, and temperature also influence REE profile shape, which helps establish genetic and timing constraints on studied deposits and improves knowledge of the metallogeny ofthe Kootenay Arc and Rocky Mountains.