Abstract
The studied area is located in the central part of the large Kızılırmak 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 and serpentine.
Tertiary layers could be divided into Lutetian, Oligo-Miocene and Pliocene subdivisions, Lutetian sediments are represented by a flysch which is made up of conglomerate, sand, marl, arenaceous limestone and limestone layers. The approximate thickness is 800 m. Oligo-Miocene sediments are represented by a series which 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 and marl layers which contain limestone beds about 1-2 m. in thickness and overly the Oligo-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 rocks in the Mesozoic sediments. Andesites and basalts are the extrusive rocks which are found in the Tertiary sediments.
During the Paleozoic, the area was completely covered by the sea. The basin was 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 uncovered until the beginning of the Eocene epoch.
After a long erosional period the Cretaceous sea covered most of the area. At the end of this period the sea was gone and after that the Eocene sea transgression took place. Toward the end of Eocene the sea regressed slowly and some lagoons were formed. During this time the sediments, which contained discontinuous gypsum beds of Upper Eocene, were deposited. At the end of Upper Eocene the sea was mostly gone and new tectonic action took place. The erosional product of these Upper Eocene rocks made up the basal conglomerate of the Oligo-Miocene sediments. At the end of Oligocene some brackish lakes remained as remnants of the vanishing Eocene sea. During the Miocene, one arm of the sea transgressing in the E-W direction covered some parts of the area, which contained varicolored series, 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 fold directions and the axis of the anticlines and synclines are seen parallel to each other in this area.
All these phenomena are the result of Alpine tectonics. Oberved angular unconformities in the Paleozoic sediments indicate the presence of the pre-Alpine tectonic movements.