Stratigraphy, Tectonic Evolution and Petrogenesis of the Volcanic Rocks in the Gördes, Demirci and Emet Basins (Western Anatolia)
Tez Türü: Doktora
Tezin Yürütüldüğü Kurum: Dokuz Eylül Üniversitesi, Fen Bilimleri Enstitüsü, Ekonomik Jeoloji (Dr), Türkiye
Tez Danışmanı: Cahit Helvacı
Tezin Onay Tarihi: 2011
Tezin Dili: İngilizce
Özet:
New stratigraphic, structural, geochemical (whole rock major and trace elements, and Sr, Nd, Pb and O isotopes) and Ar/Ar age data from the the NE–SW-trending Gördes, Demirci and Emet basins are presented. The data show that the different types of extensional to transtensional basins were superimposed, and they were all developed under ~N–S-directed extension as the Menderes Massif is episodically exhumed as a core complex.
The early-middle Miocene volcanic rocks are classified as high-K calc-alkaline (felsic), and shoshonitic and ultrapotassic (mafic), with the late Miocene basalts being transitional between the early-middle Miocene volcanics and the Na-alkaline Quaternary Kula volcanics (QKV). The geochemical characteristics of the most primitive rocks indicate that (1) early-middle Miocene volcanic rocks were derived from a Primitive Mantle-like mantle source underwent to enrichment processes, (2) the late Miocene basalts and QKV were derived from an OIB-like mantle origin, and (3) the mantle source of the early-middle Miocene volcanic rocks was distinct from those of the Eocene volcanic rocks located further north, and of the other volcanic provinces in the region. The mantle source of the shoshonitic and ultrapotassic mafic volcanic rocks was influenced by; (1) subduction-related enrichment, and (2) trace element enrichment by “multi-stage melting and melt percolation” processes in the lithospheric mantle. The influence of the latter event increases from west to east.
Geochemical features of the high-K calc-alkali felsic rocks indicate that they were derived mainly from lower continental crustal melts which then mixed with mantle-derived lavas (~20–40%). These rocks then underwent differentiation from andesites to rhyolites via nearly pure fractional crystallization processes in the upper crust, such that have undergone a two-stage petrogenetic evolution.