Abstract
Geological, petrological and geochemical studies indicate two distinct types of granitoid rocks: an older quartz diorite to granodiorite assemblage and younger granitoids, the latter occurring in two phases. The older granitoids have a calc-alkaline character, with high MgO, (FeO) t, TiO 2 and P 2O 5 and low SiO 2, K 2O and Rb. Their major and trace elements compositions, together with a low 87Sr/ 86Sr (0.7029 ± 0.0008) denote I-type affinites. The second and third phase granitoids range from calc-alkaline to alkaline respectively. The second phase granitoids have a peraluminous chemistry and high Sr, Ba, CaO, MgO, Al 2O 3 and Ti 2O, and low SiO 2, K 2O, Zr, Nb and Rb relative to the third phase granitoids. The corundum normative nature and field observations suggest that it was formed by partial melting of the lower crust (S-type). The third phase granitoids are characterized by high SiO 2, Rb, Y, Zr and low MgO, CaO, Sr and Ba values than younger granitoid phase II. They show A-type granitoids which are generated from below or within existing continental crust.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
More From: Journal of African Earth Sciences (and the Middle East)
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.