Geochemistry of major and rare earth elements in a differentiated alkaline dolerite sheet in Atsumi district, northeastern Japan.

Abstract

Major elements and RE were determined for seven representative rocks from the differentiated Nezugaseki alkaline dolerite sheet in the Atsumi district. The parental magma of the dolerite was enriched in Al2O3 compared to the other alkaline basalts. The RE abundance of the chilled basalt of the sheet may have changed during alteration. The concentration of the RE varied with differentiation but the relative abundance patterns are maintained in all the differentiated rocks. Since the RE contents in monzonitic rocks were the same as those in the dolerite main body, the monzonitic rocks may not be late differentiation products. -M.Ak.