Home – Home – Jornals – Russian Geology and Geophysics 2006 number 3

New geochemical data are reported for 63 samples of heterochronous Cenozoic basalts taken from separate areas of Mongolia. The rock compositions are strongly heterogeneous indicating lateral and temporary variability of the mantle magma sources. The Taryat-Chulutuin and Dariganga basalts were derived from the most enriched sources. The Early Cenozoic basaltoids of southern Mongolia were formed from melts compositionally close to a depleted mantle. In general, on different geochemical diagrams the compositions of the Mongolian basalts lie within the fields located among the sources of the DM, MORB, EM, PM, HIMU, REC, and OIB types. According to the melt mixture model, the average basaltic magma of Mongolia was generated from a mixture composed of 90% DM melt and 10% enriched magma. Some geochemical parameters (Sm/Nd, La/Yb, etc.) suggest that the mixed melts could have been supplied from different mantle sources. The melting depth corresponds to the region of existence of garnet-spinel lherzolite. Our geochemical data together with the earlier obtained ratios ³He/⁴He evidence the presence of a mantle plume whose composition is close to sources of alkaline magma of oceanic islands.