GEOLOGICAL CHARACTERISTICS OF THE REGION GEREDE (BOLU)

• Main Authors: TOPRAK, Özlem, AKYAZI, Mehmet
• Format: Article in Journal/Newspaper
• Language: English
• Published: NWSA Akademik Dergiler 2018
• Subjects: Gerede,General Geology,Stratigraphy,Paleozoyik,Bolu; Mengen; Planktonic foraminifera
• Online Access: https://dergipark.org.tr/tr/pub/nwsanature/issue/36660/349598

The study area covers an area ofapproximately 600km2 in the Gerede district of the Province of Bolu,which is located in 1/25.000 scale G28 a1 a2 a3 a4 topographical sheets showingnorth-west of Turkey. This study tried to reveal the general geology of thestudy region, which is bound by the Mengen district on the north and Gerededistrict on the southeast. The study area includes various rocks with similarlithology and stratigraphic sequence with ages ranging from the Paleozoic toQuaternary period. Although the base complex, which constitutes the oldest,rocks of the region, cannot be observed in the mapped geographical area inGerede, though it's known to exist at the base. The limestones developed on thetithonic facies of Late Jurassic-Early Cretaceous age on the base complex ofPermo-Triassic period are incompatible. It is determined that the UpperJurassic-Lower Cretaceous aged limestones are rich in titonic facies and richin calpionel contents. As a result of detailed paleontological andbiostratigraphic studies on the samples; 3 calpionel species and 7 species ofthese species, including Tintinnopsella carpathica (Murgeanui & Filipescu),Crassicollaria brevis Remane, Crassicollaria intermedia (Durand Delga), Crassicollariaparvula Remane, Crassicollaria massutiniana (Colom), Calpionella alpina Lorenz,Calpionella elliptica Cadisch. It was determined in the study area, the lowerlevels of Upper Cretaceous are composed of sandstone-shale-marl intercalatedflysch and clayey limestones containing agglomerate intercalations and theMaastrichtian level are composed of rocks and felsic intrusive rocks in thevolcano-flysch facies. Among Maestrichtian age-giving units; Globotruncana arcaCushman, Globotruncanita conica White, Rosita contusa (Cushman) andGlobotruncana sp. planktonic foraminifera were detected. Considering therelationship between the rocks in the region, the presence of a gradualtransgression along the Mesozoic is noteworthy. It is composed of Tertiary,Paleocene aged sandstone shales, agglomerate, Lutetian, Miocene and Neogeneaged terrestrial formations with volcanic activities, occurred in a marineenvironment and particularly observed in the western part.