10 Geochemistry and Mineralogy (Posters)

Sunday, 22 March 2026
8:00 AM - 12:00 PM
CCC, Ballroom C

Fluorine Source of the Tamazert Fluorite System (Moroccan High Atlas): Linking Syenite-Hosted Mineralization to the Canary Island Mantle Plume

Paper number: 10-7
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

  • Larbi Rddad Presenting Author
    Kingsborough Community College, City University of New York, 2001 Oriental Bvd., Brooklyn, NY - NEW YORK
  • Marta Sośnicka
    CSIRO Mineral Resources, 26 Dick Perry Avenue., Kensington, Western Australia (WA)
  • Kjell Billström
    Swedish Museum of Natural History, Box 50 007, Stockholm, Stockholm County
  • Jamal Achmani
    Hassan first University, Berrechid, Settat

Abstract

Tamazert fluorite deposits in the Moroccan High Atlas are hosted within Eocene syenite intrusions and adjacent Jurassic limestones. The syenite-hosted ores are composed of purple fluorite, calcite, and Fe-poor calcic skarn minerals. In contrast, the limestone-hosted ore assemblage comprises banded white-purple fluorite, white fluorite, and calcite. The Eocene Tamazert igneous suite, comprising syenites, pegmatites, lamprophyres, and carbonatites, collectively displays initial isotopic compositions of ¹⁴³Nd/¹⁴⁴Nd = 0.51276–0.51285, ⁸⁷Sr/⁸⁶Sr = 0.70330–0.70620, and Pb isotope ratios of ²⁰⁶Pb/²⁰⁴Pb = 18.46–19.83, ²⁰⁷Pb/²⁰⁴Pb = 15.66–15.80, and ²⁰⁸Pb/²⁰⁴Pb = 38.44–39.51. These isotopic compositions, integrated with geological and published data, suggest that these igneous rocks originated from a high µ (238U/204Pb, HIMU) mantle source linked to the Canary Island mantle plume. The magmas likely experienced limited assimilation of Jurassic limestones during emplacement, as suggested by elevated ⁸⁷Sr/⁸⁶Sr ratios and field evidence of syenites intruding into carbonate sedimentary cover. Structural analysis revealed that the faults and fractures hosting fluorite mineralization formed contemporaneously with the emplacement of the Tamazert complex, during an Eocene-Oligocene transpressive to transtensional tectonic regime shift. The Nd–Sr–Pb isotope datasets indicate that fluorite and calcite precipitated during the Eocene, from fluids genetically related to syenite magmatism. Enrichments in HFSE and LILE in early-stage fluorite and associated calcite suggest contribution of F-rich magmatic fluids, while lower concentrations in late-stage fluorite reflect subsequent fluid-rock interaction. The genesis of the Tamazert fluorite deposits is thus attributed to lateral flow of the Canary mantle plume beneath the region. These findings highlight the exploration potential of Jurassic limestones adjacent to syenite intrusions.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411126

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