Figure 2. Photomicrographs of representative NBAC plutonic and volcanic rocks (a) Microlithic porphyritic texture in basanite HG5. The microphenocrysts of olivine and augite are embedded in a groundmass of microlites of plagioclase, Fe-Ti oxide and glass. (b) Porphyritic microlitic texture with a fluid tendency in a trachyte (sample TG20). In the center, sanidine and anorthoclase microlites encompass a quartz porphyrocrystal. (c) Trachyte (sample I21) more or less altered. (d) Equigranular and porphyritic microlitic texture with corroded euhedral quartz phenocryst in rhyolite I33. Microlites of sanidine and anorthoclase, and Fe-Ti oxide granules essentially compose the fined matrix. (e, f) Fine to coarse-grained equigranular textures in alkali feldspar granites (I30, I35) showing sometimes altered alkaline feldspars. (g) Coarse-grained and intersertal texture in clinopyroxene-amphibole gabbro TG23. Pseudomorphose of augite crystals into serpentine or uralite and plagioclase minerals in the process of being sericitized. (h) Heterogranular coarse-grained texture in a syenite (I38). Alkaline feldspars are mainly perthitic and myrmekitic. Au: augite; Bt: biotite; Fk: alkaline feldspar; Hb: hornblende; Ol: olivine; Ox: Fe-Ti oxide; Myr: myrmekite; Spr: spherulite; Qzt: quartz : Petrological and Geochemical Characteristics of the Cretaceous Ngaou Boh Anorogenic Complex (Adamawa Plateau, Cameroon Line): Preliminary Constraints : Science and Education Publishing

Figure 2. Photomicrographs of representative NBAC plutonic and volcanic rocks (a) Microlithic porphyritic texture in basanite HG5. The microphenocrysts of olivine and augite are embedded in a groundmass of microlites of plagioclase, Fe-Ti oxide and glass. (b) Porphyritic microlitic texture with a fluid tendency in a trachyte (sample TG20). In the center, sanidine and anorthoclase microlites encompass a quartz porphyrocrystal. (c) Trachyte (sample I21) more or less altered. (d) Equigranular and porphyritic microlitic texture with corroded euhedral quartz phenocryst in rhyolite I33. Microlites of sanidine and anorthoclase, and Fe-Ti oxide granules essentially compose the fined matrix. (e, f) Fine to coarse-grained equigranular textures in alkali feldspar granites (I30, I35) showing sometimes altered alkaline feldspars. (g) Coarse-grained and intersertal texture in clinopyroxene-amphibole gabbro TG23. Pseudomorphose of augite crystals into serpentine or uralite and plagioclase minerals in the process of being sericitized. (h) Heterogranular coarse-grained texture in a syenite (I38). Alkaline feldspars are mainly perthitic and myrmekitic. Au: augite; Bt: biotite; Fk: alkaline feldspar; Hb: hornblende; Ol: olivine; Ox: Fe-Ti oxide; Myr: myrmekite; Spr: spherulite; Qzt: quartz

Journal of Geosciences and Geomatics. 2021, 9(4), 160-176 doi:10.12691/jgg-9-4-1