Türkiye Jeoloji Bülteni

Geology of The Çorum District

Abstract: The studied area is located in the central part of the largeKızılırmak river meander of Central Anatolia ,and the cities of Çorum, Sungurlu ,and Alaca are located in this district. Paleozoic, Mesozoic, Tertiary, ,and Quaternary sediments ,and rocks are found in this area.Paleozoic sediments contain chlorite, sericite, epidote, argillaceous ,and calcareous schists.Mesozoic sediments are mainly volcanic rocks which contain radiolarite ,andserpentine.Tertiary layers could be divided in Lutetian, Oligo-Miocene ,and Pliocenesubdivisions, Lutetian sediments are represented by a flysch which is made up ofconglomerate, sand, marl, arenaceous limestone ,and limestone layers. The approximate thickness is 800 m. Oligo-Miocene sediments are represented by a serieswhich contains discontinuous salt ,and gypsum beds between the conglomerate,sand, marl ,and clay layers overlying the Eocene sediments discordantly. Its thickness is approximately 1 000 -1 200 m. Pliocene sediments consist of the sand ,andmarl layers which contain limestone beds about 1-2 m. in thickness ,and overly theOligo-Miocene sediments discordantly.The Quaternary areas are mostly old ,and new alluvium ,and terrace deposits.In this area the gabbro ,and serpentines are represented by the magmatic rocksin the Mesozoic sediments. Andesites ,and basalts are the extrusive rocks which arefound in the Tertiary sediments.During the Paleozoic, the area was completely covered by the sea. The basinwas similar to a geosyncline. Toward the end of this time tectonic compression began ,and the land emerged above sea level. Some of these areas remained uncovereduntil the beginning of the Eocene epoch.After a long erosional period the Cretaceous sea covered most of the area. Atthe end of this period the sea was gone ,and after that the Eocene sea transgressiontook place. Toward the end of Eocene the sea regressed slowly ,and some lagoonswere formed. During this time the sediments, which contained discontinuousgypsum beds of Upper Eocene, were deposited. At the end of Upper Eocene thesea was mostly gone ,and new tectonic action took place. The erosional product ofthese Upper Eocene rocks made up the basal conglomerate of the Oligo-Miocenesediments. At the end of Oligocene some brackish lakes remained as remnants ofthe vanishing Eocene sea. During the Miocene, one arm of the sea transgressingin the E-W direction covered some parts of the area, which contained varicoloredseries, ,and caused the deposition of Miocene sediments of 2-3 m. in thickness.Fossils were found in these sediments. The direction of the layers, fault ,and folddirections ,and the axis of the anticlines ,and synclines are seen parallel to each otherin this area.All these phenomena are the result of Alpine tectonics. Oberved angular unconformities in the Paleozoic sediments indicate the presence of the pre-Alpinetectonic movements.