The basalt has porphyritic texture comporised of phenocrysts of chrysolite (>50%), pyroxene (≈35%, clinopyroxene dominant), plagioclase (≈10%), and spinel and magnetite as accessory phenocryst minerals. On several rock series identification diagrams the samples were projected in the area of tholeiite, so mineralogically and petrochemically named as dorgalite. The origin of the basaltic magma activity and the significances to the tectonic setting of the trough are discussed.