A-type granitoids, either intruded into greenschist facies volcano-sedimentary sequence or emplaced at the contact between lowand high-grade terranes, constitute a significant proportion of the granitoid rocks in the Precambrian of western Ethiopia. These granitoids are characterized by Fe-rich biotite, ferro-hornblende, alkali-amphiboles, and alkali pyroxenes. High total alkalis, high FeOT/MgO...

exact petrography and mineral chemistry investigations of pristine and altered rocks of the post-eocene panj-kuh pluton show thatsubsequent to emplacement and crystallization, rocks were subjected to two secondary composition equivalents, sodic-calcic andpotassic alterations, respectively. fresh rocks have syenitic composition and contain plagioclase (labradorite), k-feldspar, magmaticdiopside,...

Post-collisional alkaline intrusive rocks from the Dabie orogen were studied for their whole-rock major-trace elements and Sr-Nd-Hf-Pb isotopes, as well zircon U-Pb ages Hf-O isotopes. The results provide geochemical constraints on nature of mantle sources thus insight into crust-mantle interaction in continental collision zone. are composed syenite nepheline syenite. Syn-magmatic dating by LA-...

Different rock types (syenogranite, alkali feldspar granite and quartz syenite intruded by microgranite dikes veins) were investigated in the Nikeiba region Egypt. The main components of studied intrusive rocks, comprised granites syenite, are plagioclase, amphibole, biotite, K-feldspar different proportions. Ground gamma ray measurements show that syenogranite, have highest radioactivity (K, e...