Lithological Mapping of the Ayhan Basin (Central Anatolia) and Geological Implications: an Integration of Remote Sensing and Field Surveys

Abstract

The Central Anatolian Crystalline Complex (CACC), consisting of metamorphic rocks, ophiolites, and magmatic intrusions, is the largest metamorphic complex in Turkey. It is also one of the key areas for reconstruction of the subduction zones, accommodating the Africa-Europe convergence since the Cretaceous in the Eastern Mediterranean. The Ayhan Basin, chosen as the study area, is a supra-detachment basin that developed on the CACC. It has basin infill with an age ranging from Paleocene to Quaternary, interrupted by angular unconformities, and is expected to contain the whole geological record of tectonic mechanisms which have affected the region from Paleocene to Recent times. Producing a well-defined lithological map showing the structural elements of the basin is very important to understand the geological evolution of the Ayhan Basin and also to determine the spatial and temporal effects of the triggering mechanisms which deform the CACC. For this purpose, optical satellite image (Landsat TM and ASTER) processing techniques (pan-sharpening, resampling, principal component analysis, decorrelation stretching, and band combination), which have a widespread application, were used in determination of the lineaments and lithological units, having different reflectance values. After this, detailed lithostratigraphy and geological mapping of the Ayhan Basin were created by field verification. Considering the reconstructed stratigraphy and the geological map of the Ayhan Basin based on field observation and remotely sensed data, it has a depositional system that starts with continental deposits before Lutetian, then continues with marine sediments during the Eocene, and again ends with continental deposits. When the deformation processes are evaluated based on the trigger mechanisms of the Central Anatolian Crystalline Complex's (CACC) evolution, the northern and southern part of the CACC show clearly different processes. Accordingly, the boundary of the impact zone of the subduction zones in the north and south of the CACC is located between the Cicekdag and Ayhan basins.