LEVHA TEKTONİĞİ NE ZAMAN BAŞLADI? KOMATİYİTLERİN VE MgO İÇERİKLERİNİN DEĞİŞKENLİĞİNE GÖRE LEVHA TEKTONİĞİ’NİN BAŞLANGICI

Yerbilimcilerin en çok merak ettiği konulardan biri İlksel Dünya’nın (Early Earth) ne gibi evrimselsüreçler geçirerek günümüze ulaştığıdır. Bu süreçler içerisinde ise levha tektoniğinin ne zaman başladığıayrı bir araştırma konusudur. Ancak levha hareketlerinin ne zaman başladığına dair tartışmalar henüzçözüme ulaşamamıştır. Özellikle, geçmişe ait kayıtların azlığı bu tartışmaların çözüme gitmesi konusundaen büyük engellerdendir. Yerbilimciler çeşitli metodları kullanarak levha tektoniğinin başlangıç yaşınadair öneriler sunmaya devam etmektedir. Komatiyitler, Manto tarafından üretilen kayaçlar içerisinde endikkat çekenlerdir. Yaşlandırılmış en yaşlı komatiyit 3.825my; en genç ise 86my yaşındadır. İçerdikleriyüksek magnezyum oranları, özel doku ve jeolojik bulunuş koşullarıyla, güncel olarak incelenebilenherhangi bir kayaç grubuna benzemeyen bu kayaların; yerkürenin belirli jeolojik zamanları içerisindeüretilmelerine rağmen, güncel formları görülmemektedir. Komatiyitlerin oluşum koşulları, kayıtlı zamanaralıkları ve içerdikleri magnezyum oranları esas alındığında, levha tektoniğinin ne zaman başladığınadair bir gösterge olarak kullanılmaları mümkün olabilir.

WHEN DID THE PLATE TECTONICS BEGIN? THE INCEPTION OF PLATE TECTONICS BASED ON THE EXISTENCE OF KOMATIITES AND THEIR MgO VARIATIONS

The geoscientists have always wondered what evolutionary processes the Early Earth went through until it reached today. The beginning of the plate tectonics poses another matter of debate in these processes. Yet, the debates on when the plate tectonics began have not been resolved. In this sense, especially the lack of records regarding the period of time before the Cambrian Era is considered the biggest obstacle against resolution of these debates. The geoscientists have befi tted from various methods to come up with different proposals about the beginning of the plate tectonics. The most notable rock type among the ones produced by the mantle is the komatiites. While the oldest datable komatiite is 3.82 Ga; the youngest is 0.086 Ga. With the high content of magnesium they contain, their special texture and the geological setting, the komatiites are not similar to any other rock groups which can currently be examined. Though they were produced in different geological times, no up - to - date forms of these rocks have been observed. Given the formation conditions of komatiites, recorded time intervals and the content of magnesium they contain, they might indicate when the plate tectonics began.

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