Modeling of Central Anatolian (Ankara and vicinity) Basins with Gravity and Magnetic Methods

Öz

Central Anatolian basins, which are boundend by the Pontides in the north and the Kırşehir&Toros tectonic blocks to the south-southeast, geologically important structures in the region with sediment accumulations up to the present day to comprises subduction to collusion process (Senezoyik) in northern segment of the Neotethys Oceanic litosphere beneath to the Pontides. Within the scope of this study, these depositional structures, which are geographically located in Ankara and in the vicinity and classifield as the Kırıkkale-Bala, Alcı-Orhaniye, Haymana and Tüzgölü basins in litreture. Although sedimentary deposition stages, lithological properties and source characteristics show great similarities, they are considered as different basins in terms of their today’s geographical positions. In this study, these basins were examined with gravity and magnetic methods and information about their structures in the depths of the earth were obtained. Especially, the Haymana and Kırıkkale-Bala basins were found to have the thickest sediment depositions in the region (about 8-9 km). The deep structures of the basins were modeled by gravity method and their possible connections with each other were determined. In particular, it has been tried to explain the ongoing debates in the literature that Tuzgölü and Haymana basins were the same sedimentary basin in the past. Within the basin areas, no clear change in gravity data but high positive magnetic anomalies can be associated with the presence of volcanic units (Neogene) near beneath the surface. In addition, important data related to the evolution of tectonic deformation of the İAESZ on these basins have been revealed. The information of the basins with this depth provides new perspective related with the geodynamic evolution of the region, especially

considering the tectonic blocks they surround.

Anahtar Kelimeler

• 2.5D Modeling,Basin evolution,Cenral Anatolian basins,Gravity,Magnetic

Orta Anadolu (Ankara ve civarı) Havzalarının Gravite & Manyetik Yöntemler ile Modellenmesi

Öz

Orta Anadolu havzaları; kuzeyde Pontidler, güney-güneydoğudan ise Kırşehir ve Toros tektonik bloklarıyla sınırlandırılmıştır. Havzalar, Neotetis Okyanusu’nun kuzey segmentinin Pontidler altına yitim sürecini de (Senozoik) kapsayacak şekilde günümüze kadar tortul birikimleriyle bölgede önemli jeolojik yapılardır. Bu çalışma kapsamında, coğrafik olarak günümüzde Ankara ve yakın civarında yüzlek vermiş bu yapılar, literatürdeki çalışmalar dikkate alındığında; Kırıkkale-Bala, Alcı-Orhaniye, Haymana ve Tuzgölü havzaları olarak isimlendirilmektedir. Tortul birikim evreleri, litolojik yapıları ve oluşum mekanizmaları büyük benzerlikler göstermesine rağmen bugünkü bulundukları coğrafik konumları bakımından farklı havzalar olarak dikkate alınmıştır. Yapılan bu çalışmada, belirtilen bu havzalar gravite ve manyetik yöntemler ile incelenerek, daha derindeki yapıları ile alakalı bilgiler elde edilmiştir. Özellikle Haymana ve Kırıkkale-Bala havzaları, bölgedeki en kalın tortul birikimine (yaklaşık 8-9 km) sahiptirler. Havzaların yeraltındaki yapıları gravite yöntemi ile modellenerek birbirleri ile olan ilişkileri ve bağlantıları ortaya çıkartılmıştır. Özellikle, Tuzgölü ve Haymana havzalarının geçmiş jeolojik dönemlerde tek bir havza olduklarına dair literatürdeki süregelen tartışmalara gravite ve manyetik veriler ile bir açıklama getirilmeye çalışılmıştır. Havza içlerinde, gravite verisinde ani bir değişim gözlenmeyen fakat pozitif manyetik anomali veren alanlar, yüzeye yakın Neojen yaşlı volkanik birimlerin varlığı ile ilişkilendirilmiştir. Ayrıca, bölgeden geçen İzmir-Ankara-Erzincan Kenet Kuşağı’nın yine bu havzalar üzerindeki tektonik deformasyon evrimine ait önemli veriler ortaya konulmuştur. Havzaların bu derinlikle değişim bilgileri, özellikle çevrelendikleri tektonik bloklar dikkate alındığında bölgenin geçirmiş olduğu jeodinamik evrimine yönelik yeni bilgiler sunmaktadır. 

Anahtar Kelimeler

• 2.5B Modelleme,Gravite,Havza evrimi,Manyetik,Orta Anadolu havzaları

Kaynakça

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