Mantle source of the 2.44–2.50-Ga mantle plume-related magmatism in the Fennoscandian Shield: evidence from Os, Nd, and Sr isotope compositions of the Monchepluton and Kemi intrusions

Critical Controls on the Formation of Contact-Style PGE-Ni-Cu Mineralization: Evidence from the Paleoproterozoic Monchegorsk Complex, Kola Region, Russia

“…Since both alternatives have been considered as a possible source for the 2.5 to 2.44 Ga magmatism across the Fennoscandian Shield, the lack of negative Nb-Ta anomalies in some of the most primitive lithologies from the Monchegorsk Complex and the Penikat intrusion suggests that the widespread Nb-Ta depletion may not be a primary feature, inherited from the source region, but resulted from crustal contamination of asthenospheric mantle melt. This model would be consistent with recent Os, Nd, and Sr isotope data from Yang et al (2016), which also argue for a mantle plume rather than an SCLM source.…”

“…On the basis of coeval magmatism, Bleeker and Ernst (2006) suggested that the Fennoscandian Shield was situated along the southern margin of the Superior Craton at the end of the Archean. The tectonic setting as well as the mantle source of magmatism remain under debate, but most researchers prefer a rift-related mantle plume melting model followed by large-scale contamination with older felsic crustal rocks to explain the trace element and isotopic signature of the igneous rocks (Amelin et al, 1995;Barnes et al, 2001;Ciborowski et al, 2015;Hanski et al, 2001b;Puchtel et al, 1997;Yang et al, 2016).…”

“…10 B), which may indicate that the parental magma to the most primitive rocks at both intrusions may not have necessarily featured a negative Nb-Ta anomaly. This is particularly important with respect to magma derivation as negative Nb-Ta anomalies are consistent with either melting of asthenospheric mantle followed by crustal contamination or melting of the sub-continental lithospheric mantle (SCLM) (e.g., Amelin and Semenov, 1996;Hanski et al, 2001b;Huhma et al, 1990;Puchtel et al, 1997;Yang et al, 2016). Since both alternatives have been considered as a possible source for the 2.5 to 2.44 Ga magmatism across the Fennoscandian Shield, the lack of negative Nb-Ta anomalies in some of the most primitive lithologies from the Monchegorsk Complex and the Penikat intrusion suggests that the widespread Nb-Ta depletion may not be a primary feature, inherited from the source region, but resulted from crustal contamination of asthenospheric mantle melt.…”

Low-Sulfide Platinum–Palladium Deposits of the Paleoproterozoic Fedorova–Pana Layered Complex, Kola Region, Russia

“…Since both alternatives have been considered as a possible source for the 2.5 to 2.44 Ga magmatism across the Fennoscandian Shield, the lack of negative Nb-Ta anomalies in some of the most primitive rock types from the Monchegorsk Complex and the Penikat intrusion suggests that the widespread Nb-Ta depletion may not be a primary feature inherited from the source region but may have resulted from crustal contamination of asthenospheric mantle melt. This model would be consistent with recent Os, Nd, and Sr isotope data from Yang et al [20], which also argue for a mantle plume rather than an SCLM source.…”

“…On the basis of coeval magmatism, it was suggested that the Fennoscandian Shield was situated along the southern margin of the Superior craton at the end of the Archean [14]. The tectonic setting, as well as the mantle source of magmatism, remain under debate, but most researchers prefer a rift-related mantle plume melting model followed by large-scale contamination with older felsic crustal rocks to explain the trace element and isotopic signature of the igneous rocks [15][16][17][18][19][20].…”