The Kandalaksha-Kolvitsa gabbro-anorthosite complex: Nd-Sr isotope-geochronological evidence of its affinity to the East-Scandinavian Large Igneous Province

Abstract

Abstract The article provides new Sm-Nd and Nd-Sr isotope-geochronological data on rocks of the Paleoproterozoic Kandalaksha-Kolvitsa gabbro-anorthosite complex. The isotope Sm-Nd dating on metamorphic minerals (apatite, garnet, sulfide) and rock of the Kolvitsa massif yielded the age of 1887±37 Ma (high-temperature metasomatic transformation) and 1692±71 Ma (regional fluid processing). The model Sm-Nd age of metagabbro is 3.3 Ga with a negative value of εNd=-5.5, which indicates processes of crustal contamination or primary enriched mantle reservoir of initial magmas. According to geochronological and Nd-Sr isotope data, rocks of the Kandalaksha-Kolvitsa complex seem to have a common anomalous mantle source with Paleoproterozoic layered intrusions in the Baltic Shield.