Cide-kurucaşile Dolayının Jeolojisi

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Tarih
1998
Yazarlar
Sunal, Gürsel
Süreli Yayın başlığı
Süreli Yayın ISSN
Cilt Başlığı
Yayınevi
Fen Bilimleri Enstitüsü
Institute of Science and Technology
Özet
İnceleme alanı Batı Karadeniz bölgesinde Cide (Kastamonu)- Kurucaşile (Bartın) arasında kıyıya paralel ince bir şerit halinde yer almaktadır. Bölge Batı Pontid temeli, İstanbul Zonu üzerinde bulunur. Çalışma alanında çeşitli jeolojik olay ve ortamlarda oluşmuş, Karbonifer-Tersiyer aralığında gelişmiş birimler yayılır. Çalışma alanı Karboniferde karasal koşulların hüküm sürdüğü bir dönemdir. Bu dönemde bölgede, kömür ara seviyeleri de içeren akarsu fasiyesinde gelişmiş birimler çökelmiştir. Yine karasal koşullarda gelişmiş birimlerin bulunduğu Triyas dönemi akarsu ve rüzgar çökelleriyle temsil edilir. İstanbul bölgesi ve Pontidlerin diğer kesimlerinin aksine bu iki dönemde de bölge kara halindadir. Dogerde bölgede kısa süreli bir deniz ilerlemesi görülür. Malm döneminde ise bu denizel istifle uyumsuz olarak gelişmiş, daha uzun süreli bir deniz transgresyonu ile platform karbonatları çökelmiştir. Bu çökeller Neo-Tetis'in pasif kıta kenarında gelişmiş birimlerdir. Albiyen döneminde tekrar alttaki birimlerle uyumsuz olarak gelişmiş denizel çökeller görülür. Bu birimler Ulus havzasının açılımını temsil etmektedir. Troniyen-Santoniyen devrinde bölgede ilk defa volkanik birimler ve normal fay önünde gelişmiş derin denizel birimler görülür. Ulus havzasında gelişmiş birimlerin üzerinde uyumsuz olarak gelişmiş bu çökeller, Ulus havzasının kenarını oluşturan çalışma alanının, artık açılmakta olan Karadenizin kıta kenarı haline geldiğini göstermektedir. Bu birimlerin hemen üzerinde ise Troniyen-Koniasiyen döneminde, bölgesel ölçekte açısal uyumsuz olarak duran ve ana kopma uyumsuzluğunu temsil eden derin denizel birimler gelişmiştir. Kampaniyen dönemi bölgede yay özelliği gösteren volkanik kayaçların gelişimi ile temsil edilir. Bu dönem ve sonrasında gelişmiş birimler Karadeniz'in pasif kıta kenarını temsil eden çökeller niteliğindedir. Çalışma alanında kuvaterner çökelleri haricinde, Eosenden günümüze kadar çökel gelişimi gözlenmez. Bölge Eosende sıkışmalı bir rejimden etkileniş ve kuzey verjanslı, ekaylı bir yapı kazanmıştır. Bu rejim altında bir çok ters fay ve kıvrım gelişmiştir. Bu sıkışma rejimi olasılıkla bir taban kopma fayından hareketle bölgenin bugün de görülebilen ekaylı yapısının gelişmesine neden olmuştur. Bu rejim bölgede daha önceden gelişmiş jeolojik olayları tahrip etmiştir.
The study area is situated Cide (Kastamonu) and Kurucaşile towns (Bartın) in Western Black Sea, toward seaside. The investigation area covers approximately 250 km2. The area is located on Western Pontites (Ketin, 1966; Şengör and Yılmaz, 1981) (Fig.l). Western Pontites was named as İstanbul Zone by Okay et al, (1994). At the base of the İstanbul Zone, there are a group of rocks Paleozoic in age and Triassic terrestrial units. Formers represent passive continental margin sequence (Apdülselamoğlu, 1977). There are different units over the basement ranging in age from Dogger to Eocene. The area was effected different tectonic events. After the Triassic, there are three main tectonic events; the opening of the Neo-Tethian ocean in Malm (Şengör and Yılmaz, 1981), the opening of the Black Sea in Lower Cretaceous (Görür, 1989) and the closing of the Neo-Tethian ocean (Şengör and Yılmaz, 1981). The interest of the investigation is the Tertiary structures developed depending on the closure of the Neo-Tethian ocean (Şengör and Yılmaz, 1981; (Şengör, 1995). As a result of that closure, the area won an imbricated structure that has known since Grancy (1938). Fig.2 shows the general theoretical structural model for Pontides preferred by Şengör (1995). According to such model Pontides have two against imbricated vergents which are in the sought to sought and in the north to north. The aim of the study is to find out the effects of such events and development of the imbricated structure. In addition to, the geological evaluation of the area was tired to explain. The study area comprises twelve distinct units, which of two are basement units and the others are cover units. The Zonguldak formation is in the İstanbul-Zonguldak Paleozoic succession (Yılmaz et al., 1981). In the Zonguldak area, Zonguldak formation is represented by fluvial, deltaic and lacustrine sediments consist of the coal layers. Moreover in the study area, the Zonguldak formation represented by only the fluvial sediments consist of conglomerates, sandstones and mudstone intercalated with coal layers. The Çakraz formation of Triassic is represented by red coloured fluvial and aeolian sediments deposited in terrestrial processes. Base of the Çakraz unit comprise trough bedded, channel-structured conglomerates and sandstones and, laminated, planer cross-bedded, thin mudstone. In the upper part of the formation is represented by big scaled planer cross-bedded sandstones and thin bedded mudstone layers. Near of the western part of the study area, over of the Çakraz unit there is Çakrazboz formation that developed in lacustrine environment. The Çakraz formation pass the Çakrozboz formation gradually. The paleontological data derived from Çakrazboz formation gives Upper Triassic age (Alişan and Derman 1995). According to that data, the age of the Çakraz formation is accepted as Lower-Middle Triassic. The Himmetpaşa formation that belong the cover unites is the first marine unit placed in the study area. The unit begins at the base transgressively and than finishes regressively. The Himmetpaşa formation overlies the older basement unites unconformably and over of it, İnaltı formation stands unconformably. The Himmetpaşa formation indicates short-term sea exceeding the area. It is thought that the Himmetpaşa formation is the remnant of the Paleo-Tethyan ocean (Aydın et. al., 1986). The İnaltı formation of Malm is generally massive, thick bedded platform carbonates that is a transgressive series indicating of opening of the Neo-Tethian ocean (Şengör and Yılmaz, 1981). At the base of the unit, there are mudstone and sandstone alternations. Over the İnaltı formation, Ulus formation of Lower Cretaceous stands unconformably. The study area is located on the Ulus basin that opened in that time. The Ulus basin was interpreted as opening of the Black Sea (Görür, 1988; Görür et al., 1993). Yenice and Dereköy formations are the time equivalent unites, developed in Tronian-Coniacian time interval. Although their lower contact can not be seen, it is thought that, the unites overlie the Ulus formation with an unconformity. The Dreköy formation is the first unit consisting of volcanic rocks. The Yenice formation indicates olistolites that accumulated in front of the fault scarps. Both unite developed under the deep marine sea environment. The Unaz formation Tronian in age consists mainly of red coloured, thin-bedded micritic limestone and marl alternation. The formation overlies the Dereköy formation in some place with an ungular unconformity. East of the Cide town, that contact is parallel unconformity. That unite indicates general subsiding of the whole area. Such subsiding was interpreted as the major break unconformity developed during the opening of the Black Sea (Görür et. al., 1993). The Unaz formation is overlain by the Cambu formation conformably. The Cambu formation consists of mainly volcanic rocks in part with sedimentary interbeds. The formation is overlain by Akveren formation conformably. The unit consists of calc-turbidites, marls and olistolites developed in deep-sea environment. Over the Akveren formation, there is the Akveren formation stood conformably. The Atbaşı formation is represented by deep-sea red coloured and thin-bedded marls. The last unit can be observed in the field is the Kusuri formation except Quaternary unites. The formation is represented by volcano-clastic turbidites. The unites that developed after the Ulus formation are the marginal deposits of the Black Sea. Such unites are feed by the south. The area was effected by compressional regime in Eocene time. According to that regime, the area has won an imbricated structure (Fig.2). The result of the imbricating, high angle reverse faults and overturned folds developed in the area. The angles of the reverse faults in the sought are higher than the north. And the angles of the limbs of the folds in the south are less than the north. It is visible that there are two different stile deformations developed in the area in the same regime. In the south area is seen less deformed and the deformation style represented by big scale structures: open folds, steep angled faults etc. In most places the stratigraphy of the units does not disrupted. They can clearly be traced in wide areas. The reason of that structural character is the deformation exerted on more competence unites that are of older than Lower Cretaceous. Especially, depending on the carbonate content and thick bedding of İnaltı formation deformation can not be seen as penetrative.
Açıklama
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1998
Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 1998
Anahtar kelimeler
Jeolojik yapı, Kastamonu-Cide-Kurucaşile, Geological structure, Kastamonu-Cide-Kurucaşile
Alıntı