Tectonic Relations Between İzmir-Ankara Zone and Karaburun Belt

Abstract

In the Western Anatolia around Izmir region, three tectonic belts are located. These are from east to west, the Menderes massif, the Izmir-Ankara zone and the Karaburun belt. The Menderes massif is composed of metamorphic rocks, the uppermost section of which is Early Eocene in age. The Izmir-Ankara zone, which thrusted over the Menderes massif, is represented by a melange of Campanian-Danian age in a large region between Manisa and Seferihisar. This coatic unit which is named here as Bornova melange, is made up of matrix of sedimentary rocks of flysch facies and mafic volcanic intercalations and blocks of limestones more than 20 km in length in some areas. The limestone blocks and megablocks were incorporated during the sedimentation of the matrix and, as a result, various soft sediment deformations and chaotic contact relations were formed around them. The generalized stratigraphy of the megablocks, constructed from measured incomplete sections, is similar to the stratigraphy of the Karaburun carbonate succession. Besides that, lithological and paleontological correlations show that the blocks are broken parts of the Karaburun succession. In the Karaburun peninsula, the Upper Cretaceous lies with an angular unconformity, on the Triassic-Lower Cretaceous comprehensive carbonate succession, around Balıklıova village. Besides this, at two more locations, one near the villages of Karaburun and the other near Urla where the peninsula join Anatolia, caotic rocks similar to the Bornova melange are observed. At these last two locations, the contact relations between the Karaburun carbonate succession and those of the caotic rocks are similar to those seen around the megablocks of the Bornova melange, and can not be explained easily with normal stratigraphic concepts. It shows all the evidences indicative of the Karaburun succession had moved into the flysch depositing still soft sedimentary environment. Various data collected are all in agreement with the idea that the Karaburun carbonate succession was evolved as a platform of the Izmir-Ankara zone and it was tectonically transported during the flysch deposition as nappes. As the nappes moved into the Izmir-Ankara zone, broken large silices formed the megablocks, whereas, the Karaburun carbonate belt an allochthonous pack of nappes or the toe of the nappes itself.