CRUSTAL PROCESS IMPLICATIONS FOR A TECTONO-MAGMATIC EVOLUTION OF LATE CENOZOIC EGRIGOZ PLUTON IN WESTERN ANATOLIA (TURKEY)

Anatolia is located on an east-west trending fragment of the Alpine-Himalayan orogenic belt. It consists of a number of continental blocks separated by suture zones, the result of the closure of the different branches of the Neo-Tethyan ocean during the Late Cretaceous-Eocene (Sengör and Yilmaz 1981). Continent collisions in Anatolia mainly took place in two episodes: (i) the Cretaceous continent-island arc collision that predated the Pontides; (ii) the more Eocene continent-Pontide arc collision after which large volumes of post-collisional magmas erupted in western and eastern Anatolia.

The Late Cenozoic igneous province in western Anatolia is one of best examples of magmatism within continental crust that has been thickened and then thinned by orogenic processes. The Egrigöz pluton is the one of the largest and least-understood pluton. It emplaced at high crustal levels (Ozgenc and Ilbeyli 2008). The rocks have a compositional range from granodiorite to granite. They are high-K calc-alkaline and having I-type characteristics. They show linear and continuous trends in Harker diagrams (Ozgenc and Ilbeyli 2008). Linear trends can be caused by numerous petrogenetic processes, such as crustal contamination, mixing, crystal fractionation and partial melting (Cox et al. 1987; Wilson 1991). Field and geochemical characteristics of the pluton indicate an origin through partial melting of mafic lower crustal source rocks. In western Anatolia, the melt generation mechanism for the intrusive rocks could be crustal extension and uplift following collision.

References

Cox, K.G., Bell, J.D. & Pankhurst, R.J. 1987. The interpretation of igneous rocks, fifth edition. London, George Allen and Unwin Limited.

Ozgenc, I. & Ilbeyli, N. 2008. Petrogenesis of the Late Cenozoic Egrigöz pluton in western Anatolia (Turkey): implications for magma genesis and crustal processes. International Geology Review, 50, 375-391.

Sengör, A.M.C. & Yilmaz, Y. 1981. Tethyan evolution of Turkey: a plate tectonic approach. Tectonophysics, 75, 181-241.

Wilson, M. 1991. Igneous petrogenesis. A global tectonic approach, second edition. London, Harper Collins Academics.