Sr and Nd Isotopic Characteristics of Some S-, I- and A-type Granitoids from Central Anatolia

Authors : Serhat Köksal M Cemal GÖNCÜOĞLU, SERHAT KÖKSAL

Pages : 111-127

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Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :The petrogenesis of some Late Cretaceous S-, I- and A-type granitoids in the Aksaray and Kırşehir regions of Central Anatolia is investigated by means of whole-rock Sr and Nd isotope data with supplementary field, petrographic, and whole-rock geochemical studies. The S-type Central Anatolian granitoids insert ignore into journalissuearticles values(Sinandı and Namlıkışla); have calc-alkaline peraluminous characteristics and show LILE and LREE enrichment. The I-type Central Anatolian granitoids insert ignore into journalissuearticles values(Borucu, Terlemez, Hisarkaya, Baranadağ);, on the other hand, are calc-alkaline insert ignore into journalissuearticles values(excepting the alkaline Baranadağ sample); and metaluminous or slightly peraluminous with LILE and LREE enriched patterns and variable Eu-anomalies. Additionally, the A-type Çamsarı granitoid is alkaline and metaluminous with the highest LREE contents. Isotope data from the I-type Central Anatolian granitoids insert ignore into journalissuearticles values(87Sr/86Srinsert ignore into journalissuearticles values(i);: 0.7078-0.7109; eNd: -5.4 to -7.9);, and the A-type Çamsarı granitoid insert ignore into journalissuearticles values(87Sr/86Srinsert ignore into journalissuearticles values(i);: 0.7082; eNd: -7.1); are similar. The S-type Central Anatolian granitoids, on the other hand, have more radiogenic initial Sr isotopic ratios insert ignore into journalissuearticles values(87Sr/86Srinsert ignore into journalissuearticles values(i);: 0.7128-0.7152); and lower eNd values insert ignore into journalissuearticles values(-9.1 to -9.7); than the I- and A-type granitoids from Central Anatolia. When combined with the available petrological and age data, the isotope data presented in this study support the suggestion of collisional S-type granitic associations, and younger post-collisional and subsequent extensional I- and A-type magmatism in Central Anatolia. Sr and Nd isotope data infer that the I- and A-type Central Anatolian granitoids have hybrid and heterogeneous sources, while in the A-type granitoids a mantle component is likely to be dominant. Moreover, the S-type Central Anatolian granitoids were possibly derived from crustal, or crustal-dominated sources. Furthermore, the increase of 87Sr/86Srinsert ignore into journalissuearticles values(i); and decrease of eNd values observed from S-type granitoids to I- and A-type magmatic rocks is either related to distinct source characteristics or to isotopic mixing between mantle and crustal sources through time.
Keywords : Sr Nd isotope geochemistry, Central Anatolia, granitoid