Petrography, mineral chem？stry and crystallizat？on conditions of cenozoic plutonic rocks located to the north of Bayburt (Eastern Pont？des, Turkey)

The Eastern Pontides comprises of many intrusive bodies varying in composition, size and age from Paleozoic to Cenozoic. Those of especially Cenozoic aged ones are commonly observed in the southern part while are rarely exposed in the northern part of the Eastern Pontides. In this study, the petrographical and mineral chemistry properties of ？i？ekli, Somarova, Sorkunlu, ？a？urluk, Ayd？ntepe, Kemerlikda？？ and Pelitli plutons located to the north of Bayburt area are determined, and the crystallization conditions of the studied bodies were estimated by means of thermobarometer calculations. The studied plutons extend mostly NE-SW directions and are approximately ellipse in shapes. The contacts between the plutons and surrounding rocks are sharp, and plutons commonly contain mafic microgranular enclaves (MMEs) of different size. Petrographic and mineral chemistry studies reveal some disequilibrium textures reflecting magma mixing process. Based on modal mineralogy, the plutonic rocks are gabbroic diorite, diorite, tonalite, granodiorite and monzogranite in composition. The rocks have fine to medium granular, porphyric, monzonitic, poikilitic, myrmekitic and micrographic textures. The main minerals are composed of labradorite and albite (An68-02), magnesiohornblende and actinolite (Mg# = 0.6-0.9), diopside and augite (Wo44-46), clinoenstatite (En53-57) and Fe-Ti oxide minerals. Crystallization temperatures calculated from amphibole, biotite, clinopyroxene, magnetite and ilmenite minerals are 405 °C to 1161 °C, pressure values are 0.1 to 2.7 kbar, oxygen fugacity (log10 ？O2) are -20 to -12. Estimation of water content calculated by using amphiboles is between 2.9 and 6.8%. Based on obtained data, it is suggested that the studied plutons have emplaced in shallow depths (~ 1-8 km)