Turkish Journal of Earth Sciences
Article Title
Sr and Nd Isotopic Characteristics of Some S-, I- and A-type Granitoids from Central Anatolia
DOI
-
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 (Sinandı and Namlıkışla) have calc-alkaline peraluminous characteristics and show LILE and LREE enrichment. The I-type Central Anatolian granitoids (Borucu, Terlemez, Hisarkaya, Baranadağ), on the other hand, are calc-alkaline (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 (^{87}Sr/^{86}Sr_{(i)}: 0.7078-0.7109; \epsilonNd: -5.4 to -7.9), and the A-type Çamsarı granitoid (^{87}Sr/^{86}Sr_{(i)}: 0.7082; \epsilonNd: -7.1) are similar. The S-type Central Anatolian granitoids, on the other hand, have more radiogenic initial Sr isotopic ratios (^{87}Sr/^{86}Sr_{(i)}: 0.7128-0.7152) and lower eNd 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 ^{87}Sr/^{86}Sr_{(i)} and decrease of \epsilonNd 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.
First Page
111
Last Page
127
Recommended Citation
KÖKSAL, SERHAT and GÖNCÜOĞLU, M. CEMAL (2008) "Sr and Nd Isotopic Characteristics of Some S-, I- and A-type Granitoids from Central Anatolia," Turkish Journal of Earth Sciences: Vol. 17: No. 1, Article 5. Available at: https://journals.tubitak.gov.tr/earth/vol17/iss1/5