Geodynamic and Isotopic Constraints on the Genesis of Kimberlites, Lamproites and Related Magmas From the Finnish Segment of the Karelian Craton ...

• Main Authors: Dalton, Hayden, Giuliani, Andrea, Hergt, Janet, Phillips, David, O'Brien, Hugh, Ballmer, Maxim D., Maas, Roland, Woodhead, Jon
• Format: Text
• Language: English
• Published: ETH Zurich 2022
• Subjects: kimberlite; geochemistry; radiogenic isotopes; geodynamics; LLSVP; mantle plumes; Kuusamo; karelia*; karelian
• Online Access: https://dx.doi.org/10.3929/ethz-b-000565143; http://hdl.handle.net/20.500.11850/565143

Despite the scientific and economic significance of kimberlites and related magmas, their origin is unclear. Here, we address this issue using whole-rock and perovskite-derived Sr-Nd-Hf isotopes for the three occurrences of kimberlite, lamproites and ultramafic lamprophyres (UMLs) in Finland. Mesoproterozoic olivine lamproites at Lentiira-Kuhmo and UMLs at Kuusamo have different isotopic signatures yet were emplaced contemporaneously at 1,200 Ma in response to an extensional regime linked to the Baltica-Laurentia breakup. The low epsilon Nd-(i) and epsilon Hf-(i) values of the olivine lamproites are consistent with an enriched subcontinental lithospheric mantle (SCLM) source while UML compositions are intermediate between those of typical kimberlites and lamproites and are interpreted to reflect mixing of asthenospheric melts and similar to 10%-15% of melts sourced from metasomatized SCLM. The similar to 750 Ma Kuusamo kimberlites, are probably linked to the mantle plume activity that initiated Rodinia's ... : Geochemistry, Geophysics, Geosystems, 23 (8) ...