Ali UÇURUM, Musa ALPASLAN, Taner EKİCİ, Osaman PARLAK

Geochemistry of the middle Miocene collision-related Yamadağı (Eastern Anatolia) calc-alkaline volcanics, Turkey

Doğu Anadolu’daki Yamadağı volkaniklerinden ana, eser element ve K-Ar yaş determinasyonları yapılmıştır. Yamadağı volkaniklerindeki kayaçlar ortaç potasyumlu kalkalkalin bazaltik andezitler, andezitler ve dasitlerden oluşmaktadır. Petrografik olarak elek dokulu plajiyoklaz, ortopiroksenler tarafından mantolanmış klinopiroksenler, resorbe olmuş ferromagnezyan fazlar ve birbirleriyle dengede olmayan mineral toplulukları içermektedir. Kalkalkalin karakterdeki Yamadağı volkanitlerinin iz element karakteristikleri bu volkanitlerin dalma-batma zonu ve/veya kıtasal kabuk tarafından kirletilmiş volkanitlere benzeştiğini göstermektedir. K/Ar yaş tayinleri Yamadağı volkanitlerinin 12 ± 0.5 − 15 ± 0.5 My yaş aralığında oluştuğunu göstermektedir. Yamadağı volkanitlerinin jeokimyasal karakteristikleri bu volkanitlerin evriminde fraksiyonel kristallenmenin yanı sıra magma karışımı ve kabuksal bulaşma süreçlerinin etkin olduğunu göstermektedir.

Çarpışmayla ilişkili orta Miyosen yaşlı Yamadağ (Doğu Anadolu) kalkalkalin volkanizmasının jeokimyası

Major, trace element and K-Ar age determinations are reported for a suite from the Yamadağı volcanics in the Eastern Anatolia. The exposed rocks mainly consist of medium-potassium calc-alkaline basaltic andesites, andesites and dacites. Petrographical data exhibit disequilibrium mineral textures, such as resorption of the ferromagnesian phases, clinopyroxene-mantled orthopyroxene, and sieve-textured plagioclases. The Yamadağı volcanics have a calkalkaline character, and trace element characteristics exhibit that the volcanics resemble subduction zone volcanics and/or volcanics assimilated by continental crust. K/Ar age determinations show that the Yamadağı volcanics were formed during the 12 ± 0.5 − 15 ± 0.5 Ma time interval. Geochemical characteristics of these volcanics can be attributed to complex petrogenetic processes, including magma mixing and crustal assimilation along with fractional crystallization.

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