Abstract
Keban magmatics consist of plutonic rocks of acidic and intermediate compositions with diffe rent phases. They are the equivalent of surface rocks. In the current study on plutonic rocks, general petrographic features, disequilibrium textures such as skeletal formation in minerals, poikilitic texture, oscillatory zoning, and mineral fragmentation, and growth states are observed. Besides these microscopic properties, the existence of rounded mafic enclaves of various sizes, petrographic synplutonic dykes, and field data support the idea that mafic and felsic magmas are mixed. Keban magmatics have I-type, metaluminous-peraluminous characteristics. Diorites and quartz diorites have low-K tholeiitic features, whereas tonalites have low-K calcalkaline features. Compared with diorites, tonalites are richer in terms of LREE (Rock/ Chondrite); Rb, Sr, and Ba (LILE); and Hf, Zr, Th, and U (HFSE) elements. LILE enrichment, which signals the crustal contamination of mantle- originated magmas, is particularly observable in tonalites. In both rock groups, the negative anomaly of Nb is a sign of similarity of pluton to the subduction zone magma series. Based on the K-Ar geochronology dating of amphibole minerals, the ages of these rocks are found to be 75.65 ± 1.5 and 59.77 ± 1.2 Ma in tonalites and 84.76 ± 1.8 and 84.35 ± 1.7 Ma in diorite and quartz diorites. The 87Sr/86Sr isotope ratios in tonalites are 0.705405 and 0.706053, whereas these ratios are 0.704828 and 0.704754 in dioritic rocks. Pb isotope ratios are similar in both rock types.
Highlights
Within the Southeastern Anatolia orogenic belt and the Neotethys convergent system developed during the tectonomagmatic evolution of the southern Neotethys, Keban magmatics form the easternmost branch of the Göksun-Afşin, Doğanşehir, and Baskil granitoids [1,2,3,4,5,6,7,8] (Figure 1)
The objective of the current paper is to present the field relations, petrography, geochemical and isotopic (Sr-Pb) composition, and K-Ar hornblende ages of Keban magmatics
Three samples in the 208Pb/204Pb - 206Pb/204Pb diagram are found in Enriched Mantle II (EM II), and one sample from the acidic rocks is in the enriched oceanic sedimentary zone very close to the EM II zone (Figure 7(b))
Summary
Within the Southeastern Anatolia orogenic belt and the Neotethys convergent system developed during the tectonomagmatic evolution of the southern Neotethys, Keban magmatics form the easternmost branch of the Göksun-Afşin, Doğanşehir, and Baskil granitoids [1,2,3,4,5,6,7,8] (Figure 1). The study contributes in determining the location of these rocks within Cretaceous plutonic rocks spread throughout southeast Anatolia and in establishing geodynamic evolution in future regional studies
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