ULTRAMAFIC ALKALINE VOLCANIC ROCKS OF THE ZHLOBIN FIELD (BELARUS): SOURCES AND EVOLUTION OF MAGMAS

Abstract

The variations in the isotopic and trace-element compositions of ultramafic alkaline volcanic rocks from the Zhlobin fields were investigated. Variations of isotopic and trace-element compositions of volcanic rocks were related to the magmas derived from different mantle sources. Mineral composition of volcanic rocks was analyzed using a Cameca SX-50 microprobe. The interaction of ultramafic magma with crustal rocks increased oxygen potential in magma, which led to ilmenite and titanomagnetite crystallization. The variations in the concentrations of trace elements were also related to magma contamination by crustal material.