Geochemical and Petrographical Properties of Volcanic Rocks Cropping Out in the Alakırçay Melange

Abstract

The ophiolites and the ophiolitic rock units in southern Turkey are commonly observed along the Tauride belt. The Alakırçay melange, thrusted on the the Mesozoic – Cenozoic aged Bey Dağları platform carbonates in SW Turkey, consists of different rock groups in different origin. The volcanic rocks which are the subject of this study were observed as tectonic slices in the Alakırçay melange. The petrographical and geochemical properties of these rocks provide important knowledges about the tectonomagmatic events occuring before emplacement of the oceanic lithosphere onto the Tauride platform carbonates. General geochemical properties of the volcanic rocks suggest that these rocks have the alkaline character. These rocks in different tectono-magmatic discrimination diagrams exhibit the ocean island basalts or within plate alkali basalts signature. The C1/chondrite and the primitive mantle normalised diagrams for these volcanic rocks also confirmed their ocean island basalt signature. The volcanic rocks, compared with the ophiolite related metamorphic rocks, exhibit smilar geochemical charater with one part of the ophiolite related metamorphic rocks

Alakırçay Melanjı İçinde Yüzeylenen Volkanik Kayaçların Petrografik ve Jeokimyasal Özellikleri (GB Türkiye)

Öz

Güney Türkiye’de Toros kuşağı boyunca ofiyolitler ve ofiyolitik melanj birimleri yaygın olarak gözlenmektedir. Mesozoyik – Senozoyik yaşlı Bey Dağları platform karbonatları üzerine bindiren Alakırçay melanjı GB Türkiye’de yeralmakta olup bünyesinde farklı kökenli kayaç gruplarını içermektedir. Çalışma konusu olan volkanik kayaçlar Alakırçay melanjı içerisinde tektonik dilimler halinde gözlemlenmiştir. Bu kayaçların petrografik ve jeokimyasal özellikleri, okyanusal litosferin Toros karbonat platformuna bindirme süreçleri öncesindeki tektono-magmatik olaylar hakkında önemli bilgiler vermektedir. Çalışma sahasından derlenen volkanik kayaçların genel jeokimyasal özellikleri, bu kayaçların alkali özellikte olduklarını göstermiştir. Bu kayaçların çeşitli tektono-magmatik ayırım diagramlarında okyanus adası bazaltları yada plaka içi alkali bazaltları özelliklerinde oldukları görülmektedir. Bu durum, C1/kondrit’e göre normalize edilmiş nadir toprak elementleri ile primitif manto’ya göre normalize edilmiş çoklu element diagramları yardımıyla da tespit edilmiştir. Alakırçay melanjı içerisinde yüzeyleyen volkanik kayaçlar, okyanus içi yitim süreçlerinde oluşan ofiyolitlerle ilgili metamorfik kayaçların bir bölümü ile kıyaslanmış ve benzer jeokimyasal özellikler gösterdikleri saptanmıştır

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