THE CHEMISTRY OF HANNUOBA BASALTS ANDTHEIR TRENDS OF MAGMATIC EVOLUTION
汉诺坝玄武岩化学及其演化趋势

The Hannuoba basalts were erupted in Miocene. Among them the hawaiites covers a large area and also picrite-basalts and mugearites occur. Most of the Hannuoba basalts belong to alkali olivine basalt series, while a small amount of them belong to tholeiite series.Three chemical trends of magma evolution have been suggested. The Kennedy trend of differentiation from hawaiite to mugearite has been resulted from fractionation of a phenoeryst assemblege of olivine and clinopyroxene in the magma reservior in the upper crust. The straddle-B type trend of differentiation from primary hawaiite and alkali basalt through hawaiite and alkali basalt to tholeiitic basalt has been formed under the control of fraetionation of a megacryst assemblege of garnet, augite, anorthoclase and ilmenite in a magma reservior near the Moho. A new chemical trend of primary magma is suggested. The new trend from primary hawaiite through primary alkali basalt to primary picrite-basalt is resulted from the increase in the degree of partial melting of upper mantle peridotites.