Formation of the Egrikar (Gumushane) Fe-Cu skarn type mineralization in NE Turkey: U-Pb zircon age, lithogeochemistry, mineral chemistry, fluid inclusion, and O-H-C-S isotopic compositions

The Egrikar Fe-Cu skarn type mineralization is located approximately 100 km NW of Gumuhane in NE Turkey. Geochemical analyses of diorite, which is thought to cause skarn, indicate medium K calc-alkaline (1.3 to similar to 2.3 wt % K2O), metaluminous to peraluminous (A/CNK = 0.76 to 1.13) and resembles a continental arc granite. The age of U-Pb zircon obtained from diorite is 42.3 +/- 1.0 Ma, which reflects the age of skarn metasomatism after intrusion into Late Cretaceous sandy carbonates. Skarn formation zones are recognized as endo- and exoskarn. The endoskarn zone mainly consists of pyroxene with hedenbergite (Di(4.31-28.14)Hd(59.29-80.82)Jo(5.0-35.55)) at prograde stage. Mn content of pyroxene increases a slight from endo to exoskam. Pyroxene is replaced by epidote and hornblende at the retrograde stage. The exoskam zone comprises garnet with andradite (Ad(91-99)Gr(01-07)) and grossular-andradite (Ad(44.95)Gr(05-54)), epidote and quartz as silicate minerals, and magnetite and hematite as ore minerals. Magnetite is the abundant ore mineral and is accompanied by chalcopyrite and minor pyrite at retrograde stage.