Beyşehir-Hoyran Ofiyoliti İçerisindeki Tektonitlerin Dokusal ve Jeokimyasal Özellikleri: Beyşehir (Konya) Güneyinden Bir Örnek

Toros Kuşağı içerisinde Kırkkavak ve Ecemiş fayları arasında kalan Beyşehir-Hoyran Ofiyoliti, Jura sonu-Kretase başında kapanmaya başlayan Neotetis Okyanusu’na ait önemli kayıtlara sahiptir. Beyşehir-Hoyran Ofiyoliti inceleme alanında tektonitler (harzburjit, dünit), kümülatlar (gabro, piroksenolit,pegmatoitik gabro) ve ofiyolit tabanı metamorfiklerinden (amfibolit) oluşan bir istif sunmaktadır.Tektonitler ofiyolit istifi içerisinde hacimsel olarak en önemli bölümünü oluşturmaktadır. Genel olarakharzburjitlerden oluşan tektonitler yer yer dünitik ve kromitik seviyeler içermektedir. Foliyasyon-lineasyon gösteren tektonitler, kristal içi kayma, öğütülme ve yeniden kristallenme özellikleri ile üstmantoya ait plastik deformasyonun izlerini taşımaktadır. Harzburjitler genel olarak olivin, ortopiroksen,daha az oranlarda klinopiroksen ve kromit minerallerinden oluşmaktadır. Olivinler özşekilsiz, orta tanelikristaller halinde gözlenirken, ortopiroksenler olivinlere oranla daha iri kristaller şeklinde bulunur.Ortopiroksenler, tane sınırları ufalanmış ikincil olivin mineralleri tarafından çevrelenmiştir. Harzburjitlergenel olarak milonitik doku sunmaktadır. Bu birimin en belirleyici özelliği plastik deformasyonun izlerinitaşıyor olmasıdır. Makroskobik olarak ortopiroksen ve kromit gibi minerallerdeki yassılaşma ve uzamayabağlı olarak kayaçta bir foliyasyon düzleminin varlığı ayırt edilebilmektedir. Birimlerde öğütülme veyeniden kristalleşme izlerine rastlanmaktadır. İnce kesitlerde uzama gösteren olivin ve enstatitminerallerinde sıklıkla deformasyon lamellerine (kink-band) rastlanmaktadır. Yapılan jeokimyasalçalışmalarla Mg# değerlerinin 90,80-92,20, ateşte kayıp (LOI) değerlerinin ise 2,5% ile 8,5% arasında birdeğişim göstermektedir. Bu değerler bize harzburjit örneklerinin kısmen serpantinleşme sürecinebaşladığını işaret etmektedir. Peridotitlerin uyumlu elementlerce zenginleşirken, uyumsuzelementlerce tüketildiği görülmektedir. Bu özellik hem abisal hem de okyanus içi yitim zonu peridotitleriiçin tipiktir.

Textural and Geochemical Properties of Tectonites in the Beyşehir- Hoyran Ophiolite: An Example from South of Beyşehir (Konya)

Beyşehir-Hoyran Ophiolite is situated between Kırkkavak and Ecemiş faults in the Taurus Belt. It has the records of Neotethyan Ocean which began to close at the Late Jurassic-Early Cretaceous. Beyşehir- Hoyran Ophiolite in the study area is represents with tectonites (harzburgite, dunite), cumulates (gabbro, pyroxenolite, pegmatoitic gabbro) and metamorphic sole (amphibolite). Textured tectonite peridotites are volumetrically in the most important part of the ophiolite sequence. In general, composed of harzburgite, tectonite textured peridotites also includes dunite and chromite levels. Tectonites showing foliation-lineation, in crystal slip, grind and re-crystallization properties of the upper mantle is a significant traces of plastic deformation. In general harzburgite is composed of olivine, orthopyroxene, clinopyroxene and lesser amounts of chromite. Medium-grained crystals of anhedral olivines was observed in the form of orthopyroxene minerals are larger than olivine minerals. Orthopyroxenes are surrounding by secondary crumbled grain boundaries of olivines. In general harzburgite shows milonitic texture. Beyşehir-Hoyran Ophiolite tectonites of the most important properties is that traces of plastic deformation. Minerals such as orthopyroxene and chromite in macroscopically flattening and elongation depending on the foliation plane of the presence of a rock can be distinguished. Units are found traces of grinding and re-crystallization. Elongated enstatite and olivine minerals are commonly showing deformation lamellae (kink-band) in the thin section. Geochemical studies show that Mg # values are 90,80-92,20 and fire loss (LOI) values are between 2.5 and 8.5%. These values indicate that the harzburgite samples started partly to the serpentinization process. While peridotites are enriched with compatible elements, it is seen that they are consumed as incompatible elements. This feature is typical for both abyssal and intra-oceanic zone peridotites.

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