Rare Earth Elements in Alkaline-Silicate Roof Zones: Late-Stage Magmato-Hydrothermal Processes in the Motzfeldt Igneous Centre, South Greenland ...

• Main Authors: Rooks, Curtis James William, Herd, Donald Angus, Frangeskides, George, Finch, Adrian Anthony
• Format: Text
• Language: English
• Published: Deutsche Geologische Gesellschaft - Geologische Vereinigung e.V. (DGGV) 2023
• Subjects: Greenland; Igaliko
• Online Access: https://dx.doi.org/10.48380/5s5d-fv07; https://www.dggv.de/e-publikationen/rare-earth-elements-in-alkaline-silicate-roof-zones-late-stage-magmato-hydrothermal-processes-in-the-motzfeldt-igneous-centre-south-greenland

The Motzfeldt Centre forms part of the Igaliko Complex: one of the major complexes of the Mesoproterozoic Gardar Igneous Province of Southern Greenland. This syenite hosts a Ta-Nb-Rare Earth Element (REE)-Zr alkaline-silicate roof zone, containing several metals classed as “critical” to the economy by the EU. This study carries out detailed mineralogical, geochemical, and microtextural analysis of REE-enriched syenite variants from Motzfeldt using BSE-SEM imaging, EPMA, WDS mapping, and RAMAN spectroscopy. These data provide evidence that an aggressive, magmatically derived, F-rich fluid ( F 1 ) altered primary magmatic pyrochlore ( P 0 ), replacing it with mineralogically heterogeneous pseudomorphs formed of secondary pyrochlore ( P 1 ) and several alteration phases. Also found also encrusted on the surface of P 1 , these intergrown secondary phases are formed of elements lost from P 0 during alteration including Nb, REEs, F, Ca, Zr. In a second hydrothermal event ( F 2 ), these crusts are “scrubbed” from ...