Geochemical classification of Late Cenozoic basalts from Kamchatka (by neutron activation analysis data)

The method of instrumental neutron activation analysis of basalts from Kamchatka different tectonic zones for rare earths, Ta, Hf, Th contents. Also Nb and Zr concentrations have been determined by chemical spectral and X-ray radiometric methods. Three types are separated by specific features of standard rare earths distribution in basalts: tholeite one with La and Ce deficits (low-potassium series), calc-alkali one with moderate accumulation of light rare earths (calc-alkali and shoshonite series) and alkali one with a maximum concentration of light lanthanides (alkali-olivine-basalt and potassium alkali series). It is shown that classification by type of basalts on the basis of geochemical data permits to reconstruct geodynamical conditions of their formation which can be successfully used during analysis of paleovolcanic systems