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    Geochemical and mantle-like isotopic (Nd, Sr) composition of the Baklan Granite from the Muratdagi Region (Banaz, Usak), western Turkey
    (Pergamon-Elsevier Science Ltd, 2008) Aydogan, M. Selman; Coban, Hakan; Bozcu, Mustafa; Akinci, Oemer
    The (late syn)-post-collisional magmatic activities of western and northwestern Anatolia are characterized by intrusion of a great number of granitoids. Amongst them, Baklan Granite, located in the southern part of the Muratdagi Region from the Menderes Massif (Banaz, Usak), has peculiar chemical and isotopic characteristics. The Baklan rocks are made up by K-feldspar, plagioclase, quartz, biotite and hornblende, with accessory apatite, titanite and magnetite, and include mafic microgranular enclaves (MME). Chemically, the Baklan intrusion is of sub-alkaline character, belongs to the high-K, calc-alkaline series and displays features of I-type affinity. It is typically metaluminous to mildly peraluminous, and classified predominantly as granodiorite in composition. The spider and REE patterns show that the rocks are fractionated and have small negative Eu anomalies (Eu/Eu* = 0.62-0.86), with the depiction of Nb, Ti, P and, to a lesser extent, Ba and Sr. The pluton was dated by the K-Ar method on the whole-rock, yielded ages between 17.8 +/- 0.7 and 19.4 +/- 0.9 Ma (Early Miocene). The intrusion possesses primitive low initial Sr-87/Sr-16 ratios (0.70331-0.70452) and negative epsilon(Nd(t)) values (-5.0 to -5.6). The chemical contrast between evolved Baklan rocks (SiO2, 62-71 wt.%; Cr, 7-27 ppm; Ni, 5-11 ppm; Mg#, 45-51) and more primitive clinopyroxene-bearing monzonitic enclaves (SiO2, 54-59 wt.%; Cr, 20-310 ppm; Ni, 10-70 ppm; Mg#, 50-61) signifies that there is no co-genetic link between host granite and enclaves. The chemical and isotopic characteristics of the Baklan intrusion argue for an important role of a juvenile component, such as underplated mantle-derived basalt, in the generation of the granitoids. Crustal contamination has not contributed significantly to their origin. However, with respect to those of the Baklan intrusion, the generation of the (late syn)- post-collisional intrusions with higher Nd(t) values from the western Anatolia require a much higher amount of juvenil component in their source domains. (c) 2007 Elsevier Ltd. All rights reserved.
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    U-Pb zircon geochronology, Sr-Nd isotope geochemistry and petrology of Carboniferous granitic rocks in Afyon Zone (NW Türkiye)
    (Pergamon-Elsevier Science Ltd, 2026) Aslan, Zafer; Aydogan, M. Selman; Kadioglu, Y. Kagan; Yigit, Ozcan
    The Afyon Zone basement, regarded as part of the northern passive margin of Gondwana during the Late Paleozoic, comprises Paleozoic quartz-muscovite schists and phyllites intruded by Carboniferous metaplutonic bodies. The Triassic cover rocks consist of metadacite and ore-bearing metabasic. The plutonic assemblage in the area is represented by two principal intrusive phases: (i) metagranite porphyry and (ii) metagranite. Of these, age of the metagranite porphyry unit was determined to be 311.1 +/- 5.0 Ma, and that of the metagranite to be 309.3 +/- 1.9 Ma, using the U-Pb zircon SHRIMP method. Mineral chemistry analyses indicate that the temperature of the plagioclase in the metaplutonic and schist rocks is below 600 degrees C. The muscovite mineral in the schists is of the muscovite-ferromuscovite type and is crustal in origin. The metaplutonic suites correspond to S-type, peraluminous granitoids with high-K calc-alkaline affinities. Trace element distribution diagrams show enrichment in large ion radius lithophile elements (LILE; K, Rb, Th and U), while some high-field-strength elements (HFSE; Nb, Y and Sr) show depletion. The rare earth element distributions, are concave in shape (average LaN/LuN = 4-23) and exhibit a slight negative Eu anomaly (Eu/Eu* = 0.40-1.06). Both plutons are tectonically associated with a volcanic arc and formed within the continental crust. The primary magmas of the metaplutonic rocks formed through magmatic interaction with partially melted metapelitic rocks in the lithospheric mantle and the lower continental crust. Metamorphic basement rocks are high in potassium and exhibit a shoshonitic character. The average primary 87Sr/86Sr for metaplutonic rocks is around 0.720, while the 143Nd/144Nd values range from 0.512139 to 0.512257. These values suggest that the source area from which the plutons was originated from enriched-mantle. Accordingly, the Middle Carboniferous metagranitic magmatism in the Afyon Zone is interpreted to have developed within a continental volcanic arc setting associated with the southward subduction and progressive closure of the Paleotethys Ocean along the northern margin of Gondwana.