Geochemistry and origin of Pliocene alkali basaltic lavas from Anhui-Jiangsu, eastern China

Abstract

The Pliocene volcanic rocks of the Anhui-Jiangsu region of eastern China are composed of an alkali basaltic suite consisting of alkali basalts, basanites and nephelinites. The basalts underwent a limited degree of fractional crystallization dominated in the initial stage by olivine and subsequently by clinopyroxene. The magmas were derived from a metasomatized amphibole-bearing garnet peridotite source variously enriched in incompatible trace elements. The metasomatic enrichment of the incompatible trace elements was probably produced by a zone refining process and was superimposed on a depleted upper mantle source compositionally similar to that of mid-ocean ridge basalts.