سنگ‌شناسی و بررسی ترکیب شیمیایی کانی‌های مافیک سنگ‌های آذرین خروجی منطقه‌ی شمال‌شرق بیرجند

Extrusive igneous rocks are formed the main part of geological units in northeast region of Birjand. Investigation shows that these igneous rocks can be divided into rhyolitic, dacitic, andesitic and an especial group including basaltic andesite and basalts. In Later group that differ from the others according to geochemical and mineralogical characteristics, there are limited outcrops of high – K basaltic andesite, benmorite and mogearite in addition to medium – K basaltic andesites and subalkaline basalts. The composition of olivine in basaltic andesites (Fo 0.67) and basalts (Fo 0.73) is crysolite and the composition of pyroxene is diopside in basalts, augite in basaltic andesites and enstatite in andesites. The chemistry of amphiboles in intermediate volcanic rocks shows that their compositions are magnesiohornblende to tschermakite hornblende.