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    An approach to geochemical characterization of productive versus barren granitoids in terms of iron in Central Turkey
    (2004) Kuşçu, İlkay; Kuşçu, Gonca Gençalioğlu; Saraç, Cem; Meinert, Lawrence D.
    The granitoids associated with, and without skarn type mineralizations in central Anatolia are termed as productive and barren granitoids, respectively. The study of the relationships between plutonic rocks in the Central Anatolian Crystalline Complex in central Turkey suggests a direct genetic connection between the composition of plutons, and their associated ore deposits. In order to discriminate between productive and barren granitoids, two Fe-skarn granitoids (Celebi and Karamadazi), and a series of barren plutons within central Anatolia were examined. The Karamadazi and Celebi granitoids are geochemically different from other barren plutons in Central Anatolia. The parameters governing the productivity of these granitoids were determined by principal component analysis (factor analysis) method. Based on this method, the factors controlling the geochemical characteristics of the Celebi granitoids are (Al2O3 + MgO + Fe2O3 + P2O5 + TiO2 + CaO)/(SiO2), (K2O + Rb)/(Na2O) and Rb/Sr ratios, and for the Karamadazi granitoid the Fe2O3 + MnO + MgO + P2O5 + Y)/(SiO2 + Rb) (FMMY/S) and (Na2O)/(K2O) ratios. These two granitoids are clearly distinguished from the barren Central Anatolian Granitoids (CAG) on Harker diagrams based on these controlling factors (parameters). Barren CAG plutons are different from the productive Celebi granitoids in their higher silica content and generally higher total alkali values. This study suggests that iron-producing granitoids are less differentiated and receive little contribution from continental crust compared to the barren granitoids. Higher apatite and zircon abundance in the Celebi granitoids suggest that the Celebi granitoids have more I-type characteristics compared to barren plutons of CAG. The Karamad granitoid is the most striking example for the granitoids in CAG, having a higher contribution from the continental crust as evidenced by higher Rb, Ba, Th, the highest mean Sc, V, and mean Zr, Y, Ni contents. Based on the factor analysis, it is proposed that the Karamadazi granitoid displays geochemical characteristics similar to the Terlemez and Agacoren granitoids of CAG. The factor analyses indicated that the first two factors are about the same for both the Fe-producing Celebi and Karamadazi granitoids. Therefore, this similarity has let to a conclusion that the productivity or non-productivity of the granitoids in Central Anatolia can be tested by examining and comparing the distribution of granitoids in diagrams designed according to the factors defined in this study. © 2004 Elsevier Ltd. All rights reserved.
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    Tectonic setting and petrogenesis of the Çelebi granitoid, (Kırıkkale-Turkey) and comparison with world skarn granitoids
    (2002) Kuşçu, İlkay; Gençalio?lu Kuşcu, Gonca; Meinert, Lawrence D.; Floyd, Peter A.
    Many studies have shown systematic correlations between the composition of plutons worldwide and the metal content of associated skarns. This is the first report of similar correlations between the composition of Çelebi granitoid and skarns of the Çelebi district in Central Anatolia, Turkey. The Çelebi district is well known for its polymetallic Fe-W and Cu vein ores. These are hosted by calcic skarn zones. Both exoskarns (pyroxene-garnet) and endoskarns (epidote-pyroxene) occur in the district formed mainly along the granitoid contacts and along the fractures within the marble. Based on mineralogy, petrology and geochemistry, two different igneous rocks were recognized in the Çelebi granitoid, referred to as leucocratic (felsic) and mesocratic (intermediate) Çelebi granitoid. The leucocratic Çelebi occurs as dominant rock type, and is classified as granite. The mesocratic Çelebi is not widespread and is classified as adamellite, tonalite, quartz monzonite and quartz monzodiorite. The mesocratic Çelebi has I-type characteristics, and have subalkaline, calc-alkaline and metaluminous characteristics like most worldwide skarn granitoids. A post-collisional tectonic setting is proposed on the basis of field evidence, the relative timing of intrusions with respect to metamorphic and obducted ophiolitic rocks and trace element geochemistry. The high abundance of La and Ce and the enrichment of V in mafic components suggest that Çelebi granitoids are formed by partial melting of mantle rocks, but have been contaminated by interaction with continental crust involving possible magma mixing processes (i.e. mixing of coexisting felsic and mafic magmas). In the district, the mesocratic type and mafic microgranular enclaves (MME) mainly within leucocratic type represent a mafic underplating magma that was mixed with and/or injected into felsic magma of the leucocratic type. The present study shows that Fe mineralization is associated with mesocratic Çelebi type, whereas W mineralization is associated with leucocratic type. Mesocratic Çelebi granitoid is significantly different from the worldwide average of plutons associated with Fe skarns. In particular, MgO vs. SiO2, FeOt+CaO+Na2O/K2O vs. SiO2, Fe2O3/Fe2O3+FeO vs. SiO2 and V vs. Ni vary from typical values (are lower than values typical for plutons associated with Fe skarns) for plutons associated with Fe skarns. Instead, it resembles the geochemical characteristics of plutons associated with worldwide Cu and possibly Au skarns. This suggests new exploration possibilities for copper and gold in the Çelebi district.