Sivrihisar (Eskişehir, KB Türkiye) bölgesi üst jura – alt kretase karbonat platformu ve yamaç istiflerinde foraminifer ve kalpionellid biyostratigrafisi, mikrofasiyes analizleri ve tektonik çıkarımlar.


Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Jeoloji Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2017

Tezin Dili: İngilizce

Öğrenci: Serdar Görkem Atasoy

Danışman: DEMİR ALTINER

Özet:

This study focuses on the biostratigraphy, microfacies analyses and the tectonic interpretation of an Upper Jurassic – Lower Cretaceous carbonate succession widely exposed in a tectonic klippe of the Sakarya Zone (Pontides), north of Sivrihisar region (Eskişehir). For this purpose two stratigraphic sections were measured (925 m thick in total) along the carbonate rocks that crop out north of the Dümrek Village. According to the biozonation and the microfacies types, two coeval but dissimiliar depositional domains, separated by an overthrust, have been detected along the measured sections. The one on the southern part shows a slope to basin facies and is characterized by the Kimmeridgian – Berriasian Yosunlukbayırı Formation and the overlying Valanginian Soğukçam Limestone. Within these deposits the following biozones were defined: Globuligerina oxfordiana – Mohlerina basiliensis Zone (Kimmeridgian), Crescentiella morronensis (Saccocoma subzone) Zone (Lower Tithonian), Protopeneroplis ultragranulata Zone (Upper Tithonian), Crassicollaria (massutiniana subzone) Zone (uppermost Tithonian), Calpionella (alpina, Remaniella and elliptica subzones) Zone (Lower Berriasian), Calpionellopsis (simplex and oblonga subzones) Zone (Upper Berriasian) and Calpionellites (darderi subzone) Zone (Lower Valanginian). The Jurassic – Cretaceous boundary is located at the base of the Calpionella Zone. This succession overthrusted from north to south by a thin slice of the Berriasian Yosunlukbayırı Formation and an overlying thicker slice consisting of the Kimmeridgian Günören Limestone which is a part of the Edremit – Bursa - Bilecik Carbonate Platform. Within the Günören Limestone, Labyrinthina mirabilis – Protopeneroplis striata (Kimmeridgian) Zone was recognized. A much thinner section, measured to the north of these successions, consists of the Yosunlukbayırı Formation of Early Berriasian age deposited on the slope and the basinal Soğukçam Limestone. The boundary of these two formations is probably tectonic. If the positions of the studied sections with respect to the Edremit – Bursa – Bilecik Carbonate Platform is considered, the studied basin and slope facies should represent the southern platfrom margin and slope environmnets of this carbonate platform that faced an ocean to the south during the Jurassic – Cretaceous interval. The slope and basinal facies (the Yosunlukbayırı Formation and the Soğukçam Limestone) overthrusted by the shallow marine deposits (the Günören Limestone) in a region studied to the south of the main İzmir – Ankara – Erzincan (İAE) suture suggests an important disruption and shortening of the Edremit – Bursa – Bilecik Carbonate Platform margin and slope deposits probably related to the closure of the İAE ocean.