The study is conducted on the Mertule Maryam volcanic section which is located in the northwestern Ethiopian Plateau (EP). The aim of the study is to understand the petrogenesis of volcanic rocks based on their petrological and geochemical signatures. To achieve the aim of the study: geological mapping, petrographic and geochemical studies of the volcanic rocks by comparing and contrasting with the regional studied datasets have been conducted. As a result, the study area contains volcanic rocks varying in composition from basaltic rocks at the lower part through intermediate rocks (alkali feldspar-phyric trachyandesitic pyroclast and porphyritic trachyandesitic to phonolite) at the middle part to pyroxene-rich tephrite at the upper part. Petrographically, the texture of the basalts vary from aphyric through olivine-clinopyroxeneplagioclase-phyric to plagioclase-phyric up section. The texture of the intermediate rocks vary from alkali-feldspar-phyric to alkali-feldspar-hornblende-aegirine-phyric. On the other hand, the pyroxene-rich tephrites are characterized by having a texture varying from clinopyroxene-phyric to clinopyroxene-glomeroporphyritic up section. Based on geochemical analysis, the basalts are transitional; while the intermediate rocks and pyroxene-rich tephrites are alkaline in composition. Different degree of partial melting at different depths and in some cases crustal contamination were responsible for the compositional variation of the basaltic rocks; whereas both fractional crystallization and partial melting processes, without crustal contamination, were responsible for the compositional variation of the pyroxene-rich tephrites. The intermediate volcanic rocks were affected by assimilation fractional crystallization (AFC) process in their genesis. The basaltic and intermediate magmas were generated from spinel dominated amphibole-bearing spinel-garnet asthenospheric mantle sources with some interaction of the lithospheric and crustal materials. While the basanite magmas were generated from garnet dominated spinel-garnet asthenospheric mantle source.