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    The relationship between collision-related calcalkaline, and within-plate alkaline volcanism in the Karacadag Area (Konya-Turkiye, Central Anatolia)
    (ELSEVIER GMBH, URBAN & FISCHER VERLAG, 2008) Kurt, Hueseyin; Asan, Kuersad; Ruffet, Gilles
    The Karacadag (Kulu-Konya) area is one of the main volcanic provinces in Central Anatolia. The Karacadag volcanites are composed of large volumes of andesitic-dacitic lavas associated with pyroclastics and small volumes of alkali basalt, trachybasalt and trachyandesite lavas. Two groups of volcanic rocks can be distinguished: (1) calcalkaline rocks including andesites and dacites, and (2) alkaline rocks including basalts, trachybasalts and trachyandesites. Ar-40/Ar-39 ages show that the Karacadag volcanites were erupted during Early Miocene (ca. 18-19 Ma) and suggest that alkaline volcanites succeed shortly afterwards calcalkahne volcanites. Major oxides and trace elements plotted versus SiO2 Suggest fractionation of hornblende, Fe-Ti oxide and apatite for calcalkaline volcanic rocks and olivine, clinopyroxene and Fe-Ti oxide for alkaline volcanic rocks in the magmatic evolution. The incompatible trace element patterns of the calcalkaline volcanites show enrichment of LILEs (Sr, K, Rb, Ba and Th) and negative HFSEs (Nb, Ta) anomalies suggesting an enriched lithospheric source by a subduction-related process. On the other hand, alkaline volcanites show enrichment of both LILEs and HFSEs suggesting an enriched lithospheric source by small volume melts from the asthenosphere. The rocks also have moderately fractionated REE patterns with (La/LU)(N) ratios of 7-24 for calcalkaline and 6-17 for alkaline volcanites. Moreover, the volcanites have relatively low Sr-87/Sr-86(t) ratios for t = 18 Ma between 0.703782 and 0.705129, and high epsilon N-d(t) values between + 2.25 and + 4.49. Generally, the Sr-Nd isotopic compositions of the rocks range from the mantle array to bulk earth. All of these observations and findings suggest that the calcalkaline volcanites were formed in a subduction modified orogenic setting, and the alkaline volcanites in a within-plate setting. (C) 2006 Elsevier GmbH. All rights reserved.