Akademik Veri Yönetim Sistemi
Yerbilimleri, sa.30, ss.1-21, 2004 (Scopus)
In the Güre (Giresun) area, Turonian-Coniacian basalt and pyroclastics, Coniacian-Santonian dacite-rhyodacite and pyroclastics, and Campanian-Maestrichtian (?) biotite-bearing andesite and pyroclastics crop out. Upper Cretaceous-Paleocene (?) Güre Granitoid intruded into dacite/rhyodacite and their pyroclastics. The Güre Granitoid shows xenomorphic granular, fine-grained porphyric, rarely graphic and micropegmatitic textures. The rocks contain mainly quartz, orthoclase, plagioclase, hornblende, biotite, accessory apatite and sphene, secondary chlorite, epidote and calcite. Mineral thermometer and barometer calculations indicate crystallization conditions of ∼650-700°C and ∼0.9-1.5 (x̄) kbar, respectively. The Güre Granitoid has I-type, calc-alkaline, metaluminous-per-aluminous (A/ CNK=0.9-1.2) characteristics, fractionated and alumino-cafemic (ALCAF) features. Major and trace element variations indicate that fractionation was significant in the evolution of the rocks. Trace element patterns of the rocks are similar to each other but some exhibit K, Rb, Ba and Th enrichments. The rocks have moderately enriched and spoon-shaped rare earth element patterns with (La/LU)N =1-2, reflecting hornblende and plagioclase fractionations in the evolution. The Güre Granitoid evolved from a hybrid parental magma, possibly derived from arc crust and mantle sources. It was concluded that the crystallization of the granitic magma took place relatively at greather depth (∼6 km) of the arc crust, and then completed in shallow level (∼3 km) following magma uplift.