Geochemical characteristics of the Sebinkarahisar granitoids in the Eastern Pontides, northeast Turkey: Petrogenesis and tectonic implications

A series of Cretaceous to Eocene granitoids are present in the Eastern Pontides of northeastern Turkey. The Asarcik (Saplica, Catakhan), Eskine, and Saydere (Sebinkarahisar-Giresun) are the least-studied, thus least-understood plutons in the orogen. Rock assemblages range from monzonite to granite. They contain mainly K-feldspar, plagioclase, quartz, hornblende, biotite, and Fe-Ti oxides. They are high-K, calc-alkaline, and I-type granites. Chondrite-normalized REE patterns are fractionated and have small negative Eu anomalies. They show enrichment in LILE and LREE relative to HFSE, displaying features of arc-related granitoids. Low molar Al2O3/(FeO+MgO+TiO2) in combination with variable molar (Na2O+K2O)/(FeO+MgO+TiO2) ratios indicate that the magmas were derived from mafic lower-crustal source rocks. The Eu and Sr anomalies and unfractionated HREE Suggest the presence of plagioclase and absence of garnet in the source.