Kuzey Anadolu fay zonu`nun Dokurcun (Adapazarı)-Taşkesti (Bolu) kesiminde deformasyon mekanizmasının incelenmesi

Abstract

VI ABSTRACT The study area lies between Dokurcun and Taşkesti part of the NAFZ that bounds the region where the Rodop-Pontid Union and the Sakarya Continent coincide. On the basis of previous studies, 8 lithostratigraphy / lithodem units of Triassic-Quaternary period, cropping out in two distinct areas, namely Middle and Southern Zones, have been delineated, the 1/25 000 scale geologic map has been reviewed through the data obtained and, the stratigraphic, petrographic and cataclasma properties of these units have been determined. Two distinct types of tectonic deformation periods (Paleotectonic and Neotectonic) developed in different geologic times have been established in the study area and its vicinity. Within the evolution interval cold as Paleotectonic period, a series of folds and thrust faults of E-W and NNE- SSW direction have been developed as a result of the direction changes in compressional forces between N and NW. Especially, the thrust faults observed in Almacik Ophiolitic Group has mostly turned out to be mechanical surfaces and, in some places, lithological boundaries with normal autochthonous boundary characteristics have been developed. In the Neotectonic period, due to the NW-SE oriented compressional forces, a strike-slip fault tectonic has been developed and, the strike-slip faults NW-SE direction, as observed in Middle Zone rocks, have cut and offset within the scope of this mechanism. In the study area, NAFZ composes generally of a series of strike-slip faults having different directions. These faults which generally trends in E-W direction, have been mostly developed as right lateral although some left laterals have also been observed in some places. On the other hand, younger faults whose directions do not match the major trend, are observed. Besides that, starting from Paleotectonic period, local folds with different scales have also been developed in various lithological groups. These are observed in the directions representing the mechanisms which had prevailed in both periods. Normal and/or tear type faults of different scales have also been observed locally in the study area. These faults which are in accordance with the general faulting mechanism have developed either as normal faults or, as results of the predominance of vertical - slip / horizontal - slip components over the strike - slip with in the region where NAFZ has branched. The average width of the fault zone in between Dokurcun - Taşkesti is 4-5 km. Joint system analysis has also been applied in the study area. Since they have been developed both in the Paleotectonic and in Neotectonic periodsvıı and, block tectonic has been predominant, they exhibit in varying directions. Therefore, diagrams can only be evaluated on the basis of latest tectonic period mechanism. The evaluations, excepting some abnormalities, indicate that the joint systems are observed to be in accordance with strike-slip faulting mechanism. Earthquake data have also been utilised to determine the regional seismicity, to explain the faulting mechanism and to correlate them with the available tectonic data. The earthquake data provide some extra evidences supporting the results obtained through tectonic evaluations. These evaluations indicate that the earthquake foci comply with the major fracture zones and, crustal thickening exists in the northern parts of the area. Moreover, tectonomorphologic views of the area have also been prepared to illustrate the morphology which had been developed under the effects of three-dimensional tectonics. With these studies, the observed results have been evaluated and the faulting mechanism is determined according to the aim of thesis.

VI ABSTRACT The study area lies between Dokurcun and Taşkesti part of the NAFZ that bounds the region where the Rodop-Pontid Union and the Sakarya Continent coincide. On the basis of previous studies, 8 lithostratigraphy / lithodem units of Triassic-Quaternary period, cropping out in two distinct areas, namely Middle and Southern Zones, have been delineated, the 1/25 000 scale geologic map has been reviewed through the data obtained and, the stratigraphic, petrographic and cataclasma properties of these units have been determined. Two distinct types of tectonic deformation periods (Paleotectonic and Neotectonic) developed in different geologic times have been established in the study area and its vicinity. Within the evolution interval cold as Paleotectonic period, a series of folds and thrust faults of E-W and NNE- SSW direction have been developed as a result of the direction changes in compressional forces between N and NW. Especially, the thrust faults observed in Almacik Ophiolitic Group has mostly turned out to be mechanical surfaces and, in some places, lithological boundaries with normal autochthonous boundary characteristics have been developed. In the Neotectonic period, due to the NW-SE oriented compressional forces, a strike-slip fault tectonic has been developed and, the strike-slip faults NW-SE direction, as observed in Middle Zone rocks, have cut and offset within the scope of this mechanism. In the study area, NAFZ composes generally of a series of strike-slip faults having different directions. These faults which generally trends in E-W direction, have been mostly developed as right lateral although some left laterals have also been observed in some places. On the other hand, younger faults whose directions do not match the major trend, are observed. Besides that, starting from Paleotectonic period, local folds with different scales have also been developed in various lithological groups. These are observed in the directions representing the mechanisms which had prevailed in both periods. Normal and/or tear type faults of different scales have also been observed locally in the study area. These faults which are in accordance with the general faulting mechanism have developed either as normal faults or, as results of the predominance of vertical - slip / horizontal - slip components over the strike - slip with in the region where NAFZ has branched. The average width of the fault zone in between Dokurcun - Taşkesti is 4-5 km. Joint system analysis has also been applied in the study area. Since they have been developed both in the Paleotectonic and in Neotectonic periodsVI ABSTRACT The study area lies between Dokurcun and Taşkesti part of the NAFZ that bounds the region where the Rodop-Pontid Union and the Sakarya Continent coincide. On the basis of previous studies, 8 lithostratigraphy / lithodem units of Triassic-Quaternary period, cropping out in two distinct areas, namely Middle and Southern Zones, have been delineated, the 1/25 000 scale geologic map has been reviewed through the data obtained and, the stratigraphic, petrographic and cataclasma properties of these units have been determined. Two distinct types of tectonic deformation periods (Paleotectonic and Neotectonic) developed in different geologic times have been established in the study area and its vicinity. Within the evolution interval cold as Paleotectonic period, a series of folds and thrust faults of E-W and NNE- SSW direction have been developed as a result of the direction changes in compressional forces between N and NW. Especially, the thrust faults observed in Almacik Ophiolitic Group has mostly turned out to be mechanical surfaces and, in some places, lithological boundaries with normal autochthonous boundary characteristics have been developed. In the Neotectonic period, due to the NW-SE oriented compressional forces, a strike-slip fault tectonic has been developed and, the strike-slip faults NW-SE direction, as observed in Middle Zone rocks, have cut and offset within the scope of this mechanism. In the study area, NAFZ composes generally of a series of strike-slip faults having different directions. These faults which generally trends in E-W direction, have been mostly developed as right lateral although some left laterals have also been observed in some places. On the other hand, younger faults whose directions do not match the major trend, are observed. Besides that, starting from Paleotectonic period, local folds with different scales have also been developed in various lithological groups. These are observed in the directions representing the mechanisms which had prevailed in both periods. Normal and/or tear type faults of different scales have also been observed locally in the study area. These faults which are in accordance with the general faulting mechanism have developed either as normal faults or, as results of the predominance of vertical - slip / horizontal - slip components over the strike - slip with in the region where NAFZ has branched. The average width of the fault zone in between Dokurcun - Taşkesti is 4-5 km. Joint system analysis has also been applied in the study area. Since they have been developed both in the Paleotectonic and in Neotectonic periods