Geochemistry of bimodal volcanic rocks suites of Mekane Selam area, Northwestern Ethiopian volcanic plateau

The geochemistry of volcanic rocks in the Mekane Selam area was characterized by trace and major elements geochemistry. The area comprises alkali and transitional basalts with felsic volcanic rock products. Relatively lower contents of MgO wt% (4.88–9.83) and compatible trace elements (e.g. Ni 22–74 ppm and Cr 47–184 ppm) indicate that the basaltic rocks have undergone some degree of fractionation except for anomalously high MgO (11.28 wt%), Cr (988 ppm), and Ni (487 ppm) of the highly alkali basaltic rocks. Chondrite normalized REE spider plots of the study area basaltic rocks show enrichment of Pb and slight depletion of Rb and K and that of the trachytic and rhyolitic rocks show depletion of P, Ti, Sr with the uniform flat trend of other trace elements and REE. The existence of Eu anomaly i.e. slight depletion of Eu is observed in trachytic and rhyolitic rocks. The MgO vs SiO ₂ and other compatible and incompatible trace elements indicate fractional crystallization, crustal contamination, and magmatic mixing processes that play a significant role in the formation and evolution of the different volcanic rocks in the area.