| Autor: |
Sungu L. Gökçen, Gürol Ataman |
| Rok vydání: |
1973 |
| Předmět: |
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| Zdroj: |
Sedimentary Geology. 9:235-260 |
| ISSN: |
0037-0738 |
| DOI: |
10.1016/0037-0738(73)90064-x |
| Popis: |
Two thousand meters of Paleogene clastic sediments (mainly epiclastics) exposed in the Kesan area, southwestern Turkish Thrace (southwestern Alpine Ergene basin) have been studied and the stratigraphic sequence divided into two major lithostratigraphic units: (1) the Kesan Formation (sandy); (2) the Yenimuhacir Formation (muddy). The Kesan Formation consists of non-cyclic Cinarlidere (Upper Eocene) and cyclic Saplidere (Lower Oligocene) members. Volcanic rocks occur at three different localities of the Cinarlidere member and are interbedded (contemporaneously) with clastics. Clastics beds are generally gently tilted (at 15°–25° towards the north) and present a long outcrop along the strike. Two key horizons were followed along the strike approximately 10 km from west to east. On the basis of certain sedimentary structures, the Kesan Formation has been defined as a “sandy turbidite sequence” and statistical treatment of paleocurrent directions shows that the mean current direction of two members of this formation are in opposite directions. The quantitative analysis of structural and textural features makes it possible to distinguish two groups of turbidites: “proximal” and “distal”. These two groups of sandstones are designated as “sedimentary facies” and their occurrence is explained on the basis of the flow regime of the currents. The compositional analysis of light and heavy fractions of both member sandstones of the Kesan Formation showed marked petrological variations. The existence of two distinct “compositional facies” was established by computational statistics. Analysis of composition and current-direction data suggests that two main sources have provided materials for the formation of the Kesan sandstones. These are: (1) the Biga massif to the south-southeast, for the Cinarlidere sediments; and (2) the Rodop massif to the west-northwest, for the Saplidere sediments. Finally, the sedimentation history of the Paleogene Kesan Beds in relation to volcanic activity and the facies development in the Kesan basin have been examined and the origin of the upper member turbidite cyclicity has been discussed. Conclusions are as follows: 1. (1) Although the direction of the axis of the depositional basin, (the Kesan as well as the Ergene basin) remained constant during the Paleogene, its axial plunge has changed its direction twice; once west-northwest (in Cinarlidere) and once south-southeast (in Saplidere). 2. (2) The epiclastic and volcanic sedimentary (“pyroclastics”) deposits of the Kesan Formation have not been produced by the contemporaneous volcanic activity in the area: their source appears to be outside the basin of deposition. 3. (3) The tectonic structures of the Kesan area show that north—south oriented major stresses have been dominant and here tectonic evolution was younger than deposition. 4. (4) It can be postulated that the Ergene basin started to become a “stratigraphic basin” either at the beginning of or possibly earlier than the Paleogene. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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