U–Pb zircon ages and petrogenesis of the Late Cretaceous I-type granitoids in arc setting, Eastern Pontides, NE Turkey. (February 2021)

• Record Type: Journal Article
• Authors: Kaygusuz, Abdullah; Arslan, Mehmet; Temizel, İrfan; CemYücel, ; Aydınçakır, Emre
• Is Part Of: Journal of African earth sciences. Volume 174(2021)
• Publication Date: 2021-02
• Subjects: I-type granitoids -- Geochronology -- Crustal contamination -- Lithospheric mantle -- Eastern pontides -- NE Turkey; Earth sciences -- Africa -- Periodicals; Earth sciences -- Middle East -- Periodicals; Geology -- Africa -- Periodicals; Geology -- Middle East -- Periodicals; Sciences de la terre -- Afrique -- Périodiques; Sciences de la terre -- Moyen-Orient -- Périodiques; Géologie -- Afrique -- Périodiques; Géologie -- Moyen-Orient -- Périodiques; Earth sciences; Geology; Africa; Middle East; Periodicals; Electronic journals; 556.05
• DOI: 10.1016/j.jafrearsci.2020.104040
• Languages: English
• ISSNs: 1464-343X

Abstract

Abstract: The Eastern Pontides Orogenic Belt (EPOB) as a well-preserved ancient magmatic arc situated in the eastern part of the Sakarya Zone and has key importance to allow for proper reconstruction of the geodynamic evolution of the region. The region accepted as important part of Alpine–Himalayan Belt comprises of many granitoids of the Late Cretaceous age. This paper presents new mineral chemistry, bulk-rock petrochemistry, U-Pb geochronology and radiogenic and stable isotope geochemistry data from the Arpaköy and Oyman granitoids in the north part of the EPOB to interpretation of the igneous activity and geodynamic evolution of the region in Late Cretaceous era. Emplacement ages of 86.82 ± 0.58 Ma for the Oyman granitoid and 82.0 ± 2.3 Ma for the Arpaköy granitoid according to laser ablation ICP-MS U–Pb zircon dating. The Arpaköy granitoid are gabbro diorite, diorite and granite, whereas the Oyman granitoid are tonalite and granite in composition. They show metaluminous-peraluminous transitional (ASI = 0.79–1.20) low to medium-K calc-alkaline features. The rock samples from granitoids are characterized by enrichment in large ion lithophile elements (LILE) and high field strength elements (HFSE) depletion with concave-upward shapes (LaN /LuN = 1.88 to 6.04). The crystallization temperatures are 648 °C–913 °C and the pressure values are 0.2–3.0 kbar, which indicates emplacement depth of the studied granitoids varying from ~1 to 9 km correspond to shallow crustal depths. They show considerable variations in εNd(i) (−4.02 to 1.50) and 87 Sr/ 86 Sr(i) (0.70478–0.70689). The 206 Pb/ 204 Pb ratios are between 17.97 and 18.65, and δ 18 O are varying from +5.4 to +9.3‰. The parental magma of the Arpaköy and Oyman granitoids originated from a melt of the enriched lithospheric mantle and the fractional crystallization and lesser assimilation processes has important role on the evolution of magmas in the shallow crustal levels. Highlights: Arpaköy and Oyman granitoids were emplaced at ~ 86 - 82 Ma. Granitoids show I-type, low to medium-K calc-alkaline and metaluminous to peraluminous features. Granitoids have similar geochemical and Sr-Nd-Pb-O isotopic compositions. Granitoids crystallized at shallow crustal depths. Their magmas were generated from the enriched lithospheric mantle.