Magma Sources of Triassic Lamproites of Gornyi Altai and Taimyr: Sr and Nd Isotope Evidence for Plume-Lithosphere Interaction

摘要

Products of the Permian-Triassic within-plate mag-matism are widespread in Eurasia. On the Asian part of the continent, they are represented by flood basalts of the Siberian Craton, Gornyi Taimyr, Barents and Kara seas, West Siberian Platform and associated Kuznetsk Basin, and Emeishan province (Yangtze platform). This magmatism was caused by the impact of super-plume on the lithosphere with the peak activity at 250 ± 3 Ma. Based on the age and isotope-geochemical similarity between flood basalts and some syenite-granitoid intrusions in the folded framing of the Siberian Craton, the possibility of the direct involvement of plume in the generation of felsic magmas is considered in [3,4]. According to Ar-Ar, K-Ar, and Rb-Sr isotope datings, the final stages of flood basaltic magmatism are presumably correlated with lamproites of Taimyr (230-225 Ma) and Gornyi Altai (245-236 Ma). The Nd and Sr isotope data presented in this paper suggest a significant mixing of plume component with enriched lithospheric mantle and continental crust during the generation of hybrid lamproite magma.