Petrography and Geochemistry of the Ghar-e-Hira, Makkah, Saudi Arabia

Abstract

Petrographic study, SEM images, mineral chemistry and whole-rock geochemistry were performed on a rock sample from Ghar-e-Hira. It is medium-grained, subequigranular, and comprises plagioclase (sodic andesine), quartz, K-feldspar, biotite, opaque oxide, muscovite and sphene. Some biotite is altered to chlorite. The small quantity of K-feldspar suggests that the rock is tonalite. The high amounts of SiO2 and Al2O3 with substantial CaO and Na2O, and high Na2O/K2O support the petrography in classifying the rock as tonalite. The peraluminous nature of the rock suggests a sedimentary protolith