Gördes, Demirci ve Emet havzalarındaki (Batı Anaolu) volkanik kayaların stratigrafisi, tektonik evrimi ve petrojenezi

KD-GB uzanımlı Gördes, Demirci ve Emet havzasından elde edilen yeni stratigrafik, yapısal, jeokimyasal (toplam kaya ana ve iz element, Sr, Nd, Pb ve O izotopları) ve Ar/Ar yaş verileri sunulmuştur. Veriler, farklı tiplerde genişlemeli ve transtensiyonal havza tiplerinin farklı evrelerde ve Menderes Masifi'nin çekirdek kompleksi şeklinde episodik olarak yüzeylemesi sırasında K-G yönlü genişlemeli tektonik rejim altında meydana geldiğini gösterir. Erken-orta Miyosen volkanik kayaları yüksek-K kalk-alkali, şoşonitik ve ultrapotasik olarak sınıflanır. Geç Miyosen bazaltları erken-orta Miyosen volkanitleri ile Na-alkali Kuvaterner Kula volkanitleri (KKV) arasında geçişli jeokimyaya sahiptir. En ilksel kayaların jeokimyasal özellikleri; (1) erken-orta Miyosen volkanik kayalarının orijinal olarak İlksel Manto benzeri olan ve daha sonra zenginleşmiş olan bir manto kaynağından türediğini ve bu kayaların manto kaynağının, kuzeydeki Eosen volkanitlerinden ve çevredeki diğer volkanik kayalardan farklı olduğunu gösterir. Şoşonitik ve ultrapotasik mafik volkanik kayaların manto kaynağı yitim ilişkili ve litosferik manto içinde meydana gelen ?çok evreli ergime ve ergiyik etkileşimi? işlevler ile zenginleşmiştir. Bu zenginleşmenin etkisi batıdan doğuya doğru artar. Yüksek-K, kalk-alkali feslik volkanik kayaların iz element özellikleri bunların başlıca alt kabuğun ergimesinden türeyen magmaların mantodan türeme magmalar ile karışarak oluştuklarını gösterir. Bu kayalar daha sonra üst kabuktaki ayrımlaşmalı kristalizasyon işlevleri ile andezitlerden riyolitlere evrilmiştir ve iki evreli petrojenetik evrime sahiptir. New stratigraphic, structural, geochemical (whole rock major and trace elements, and Sr, Nd, Pb and O isotopes) and Ar/Ar age data from 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 volcanites and the Na-alkaline Quaternary Kula volcanites (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 mantle source of these 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 enrichment processes related to subduction and ?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. These rocks then underwent differentiation from andesites to rhyolites via nearly pure fractional crystallization processes in the upper crust

Stratigraphy and geochemical features of the early miocene bimodal (ultrapotassic and calc-alkaline) volcanic activity within the NE-trending Selendi Basin, western Anatolia, Turkey

Western Anatolia has experienced thickening and orogenic collapse subsequent to the Eocene continent-arc collision. The early stage of the post-collisional volcanism in the region was thought to have produced widespread lavas and pyroclastic deposits of calc-alkaline basaltic andesite to rhyolite composition. However, in the Selendi Basin, one of the NE-trending basins in western Anatolia, there are two distinct volcanic unit compositions associated with the Lower Miocene sedimentary rocks: ( 1) a calc-alkaline, high-potassic felsic unit; and ( 2) alkaline, ultrapotassic lamproitic units, i.e. both are bimodal in character. The calc-alkaline felsic volcanic rocks ( Egreltidag volcanic unit) are composed of wide-spread pyroclastic rocks and lava flows, whilst the ultrapotassic-lamproitic mafic rocks ( Kuzayir lamproite) consist of small-volume syn-sedimentary lava flows. The geochemical characteristics of the Kuzayir lamproite are similar to those of the 'Mediterranean lamproites' that were widely produced in post-orogenic tectonic settings. A temporal and spatial association between these volcanic units clearly describes a post orogenic bimodal volcanic activity. The data also imply that the continental extensional tectonic regime in western Anatolia began, at least, in the Early Miocene, and produced not only calc-alkaline felsic activity but also mantle-derived alkaline, ultrapotassic volcanic rocks

Miocene-Quaternary volcanism and geodynamic evolution in the Pannonian Basin and the Menderes Massif: A comparative study

Neogene volcanic rocks emplaced in the Pannonian Basin (PB) and Menderes Massif (MB) extensional basin systems share the same time interval and show some similarities in major and trace element geochemistry. In the PB, production of large volumes of rhyolites at similar to 22 Ma indicates an important crustal source region. Subsequently, large andesitic volcanism was derived from the mixing of magmas from both crustal/lithospheric mantle sources; further magmas, up to 11 Ma, have lower volumes and a lithospheric mantle origin. Overtime, the metasomatic components diminished in the lithosphere and this ultimately resulted in the eruption of magmas with a distinct asthenospheric character (intra-plate-related). At similar to 10 Ma, mixing of lithospheric and asthenospheric magmas resulted in the generation of transitional rocks, with basaltic and basaltic andesitic compositions. Intermittent, but continuous local generation of small volume Na-alkalic basalts at 12-10 Ma in the Styrian Basin and between 8 and 0.13 Ma in the central part of the PB, suggests a long period of small volume asthenospheric melt production via decompression melting