Mineralogy and Magmatic Processes of Cenozoic Intraplate Alkaline Volcanic Rocks of Bafang and Its Environs (Cameroon Volcanic Line, West Africa)

Abstract

Alkaline basalts of Bafang and its environs are consisted of feldspars, olivines, pyroxenes and oxides which appear as phenocrysts, microphenocrysts and microcrysts. Feldspars are plagioclases (An 67.97-15.84 Ab 69.19-30.43 Or 20.59-1.51 ) and anorthoclases (Ab 68.11-61.20 Or 33.87-20.91 An 10.98-4.93 ). Plagioclases are the most abundant amount these feldspars. Anorthoclases appear only in mugearite (BAF 3 and BAF 37) the most differentiated of the studied alkaline-basalts. In High Magnesian basalt, (HMg-B) plagioclases are labradorites (An 67.97-59.30 Ab 38.74-30.43 Or 2.75-1.60 ) and sanidine (An 45.44-31.82 Ab 62.66-51.79 Or 5.52-2.77 ), whereas in Low Magnesian basalt (LMg-B) there are labrador (