Genesis of a Magnetite Layer in the Gabbro-10 Intrusion, Monchegorsk Complex, Kola Region: U–Pb SHRIMP-II Dating of Metadiorites

The Gabbro-10 intrusion is located in the southeastern part of the Early Proterozoic Monchegorsk layered complex of the Kola region. The intrusion, 1.4 × 0.7 km in size, is composed of metagabbroic rocks and metadiorites with a sandwiched magnetite layer up to 2 m thick. For the first time, U–Pb SHRIMP-II ages were determined for zircon and baddeleyite from metadiorites with magnetite dissemination. The age of magmatic crystallization of baddeleyite (2498 ± 6 Ma) supports the intrusive origin of these rocks and the relationship of V–Ti magnetite mineralization with the ore-magmatic system of the Monchegorsk complex.