Petrographical and geochemical features of the Güneydere (Bayburt) Pluton

The Eastern Pontide Orogenic Belt that formed during the Alpine-Himalayan orogeny which geologically plays an important role in the formation of the Anatolian Plate, is a significant area in terms of containing different igneous rocks. Particularly, Carboniferous plutons are widely observed in larger outcrops and more commonly in the southern part of eastern Pontides. This study presents new petrography and geochemical data on granitic rocks in the Güneydere area of Bayburt. In addition, the source region, petrological processes, and geodynamic environment, which play an important role in the formation of rocks, are also discussed. The rocks, which include an area of approximately 5 km2, represent the pre-Jurassic basement in the study area and are unconformably overlain by Early-Middle Jurassic volcanoclastics and Late Jurassic-Early Cretaceous limestones. They mainly consist of granite/granite porphyry and aplite, to a lesser extent granodiorite and quartz monzonite. Rocks have high SiO2 contents and high K calc-alkali to shoshonitic affinities and have been derived from an I-type source. The rocks are metalumine-peralumine in character and are similar to post-collisional volcanic arc granitoids. Geochemical element trends show that plagioclase, hornblende, biotite, apatite, and Fe-Ti oxide mineral fractionations play an important role. It has been revealed that fractional crystallization and assimilation±magma mixing processes play a role in the development of granites. Zircon-saturation temperatures reflect lower initial magma temperatures. All obtained data suggest that parental magma of rocks have evolved from lower/middle crust-derived melts as a result of partial melting and differentiated and emplaced in the continental magma chamber.