Kaan Sevki Kavak

Tectonic Setting and Evolution of the Sivas Basin, Central Anatolia, Turkey

The Sivas Basin is one of several Central Anatolian basins. It developed mainly after the closure of the northern branch of Neotethys. Its location between the Kirsehir Massif and the Taurides impl...

Minibasins and salt canopy in foreland fold‐and‐thrust belts: The central Sivas Basin, Turkey

The Sivas Basin in the Central Anatolian Plateau (Turkey), which formed in the context of a foreland fold-and-thrust belt (FTB), exhibits a typical wall and basin (WAB) province characterized by symmetric minibasins separated by continuous steep-flanked walls and diapirs. Extensive fieldwork including regional and detailed local mapping of the contacts and margins of minibasins, and interpretation of a set of 2-D regional seismic lines, provide evidence for the development of a shallow evaporite level separating two generations of minibasins within the WAB province. Here beds of symmetric exposed minibasins along diapir flank are younger than minibasins observed over autochthonous evaporites. Laterally away from the WAB province, increase in wavelength of the tectonic structures suggests a deepening of the decollement level. We interpret that a shallower evaporite level developed in the form of an evaporite canopy, triggered by significant lateral shortening. The Upper Eocene-Lower Oligocene autochthonous Tuzhisar evaporite level was remobilized by the northward migrating sedimentary load and the tilting of the southern basin margin during propagation of the foreland fold-and-thrust belt. Asymmetric and symmetric primary minibasins were overrun by an allochthonous sheet forming a canopy. A second generation of salt withdrawal minibasins subsided into the allochthonous salt sheet. The polygonal pattern of the WAB province influences the growing fold-and-thrust belt system during the late stage of the secondary minibasins development. The Sivas FTB basin is the result of the interaction between fold-and-thrust belt propagation, evaporite remobilization, and interaction between evaporite flow and sedimentation in the minibasins.

Recognition of gypsum geohorizons in the Sivas Basin (Turkey) using ASTER and Landsat ETM+ images

The Tertiary Sivas Basin contains widespread, tectonically deformed deposits of massive Oligocene gypsum. This unit is one of the most important factors controlling the tectono‐stratigraphic evolution of the basin insofar as these deposits are interpreted as décollement levels. As a considerable fold and thrust belt, the Sivas Basin also has a remarkable structural expression within these evaporite deposits, as seen in satellite images aided by colour composites. Because of the arid climatic conditions of the region, the basin provides ease of interpretation geologically in terms of the synoptic‐view capability of broad‐band multispectral data sets, such as ASTER and Landsat ETM+. In this study, various processing methods — such as data fusion and decorrelation stretching — were applied to highlight Oligocene gypsum deposits of the basin.

Tectonostratigraphy of the Southern Sivas Tertiary Basin (Central Turkey) and Comparison with Landsat MSS Imagery

The Sivas Basin is one of the most important sedimentary basins, in terms of tectonics and hydrocarbon potential, in the Central Anatolian region of Turkey. Its development is related mainly to the closure of the northern branch of the Neotethyan ocean, as well as to influences of the closure of the Inner Tauride ocean. This basins complex history is related to several successive orogenic phases during the Cenozoic. Other interesting characteristics of this basin, as in the Central and Eastern Anatolian basins, are the tectonics and lithological features associated with the younger gypsum deposits. The study area comprises two distinct regions, namely the Savcun and Karacaoren areas. The primary stratigraphie relationships between Lutetian turbidites, Oligocene continental gypsum and detritics, and lower to middle Miocene continental deposits of the Savcun area have been elucidated. In this part of the study area, S-verging imbricated thrust systems, mainly located within the gypsum series, developed dur...

Enhancement facilities of SPOT XS imagery in remote sensing geology: An example from the Sivas Tertiary Basin (central Anatolia/Turkey)

The main goals of this study were to increase the data quality of the SPOT XS imagery for differentiation of several rock units and to expose the structural features of the southern part of the Sivas Tertiary Basin. With these aims, both edge enhancement and histogram equalized stretching filters were applied to SPOT XS imagery of the southern part of the basin. Various geological observations and kinematic fault measurements formed the field-based components of this work. In this study, evaluations of detailed mapping work and kinematic analyses of mesoscobic fault planes were realized together with the study of image processing data. This basin is one of the most studied and important Tertiary basins in central Anatolia due to Neotethyan evolutionary processes. When the tectonostratigraphic relationships of the study region were taken into consideration, the detailed geological interpretations were evaluated according to the concept of thrust tectonics. In this region, four different main thrust sheets, which moved from the south-east to the north-west, were distinguished. The most striking tectonostratigraphic and geomorphological phenomenon was observed in the contact zone of the Oligocene evaporitic sediments and Lower-Middle Miocene detritic series. Evaporites can be easily observed as decollement levels over the Lower-Middle Miocene series tectonically. The dominant compression direction for this region was exposed actively in a NW-SE direction after the Lower-Middle Miocene and was in agreement with the results of field and laboratory studies.

Determination of neotectonic features of the Karasu Basin (SE Turkey) and their relationship with Quaternary volcanic activity using Landsat ETM+ imagery

The junction between the East Anatolian and the Dead Sea fault zones lies close to an unstable F: Transform fault (FFF) triple junction where the African, Eurasian and Arabian plates meet in south-eastern Turkey. The Karasu Basin is an ephemeral rifted structure located close to the junction of these plate boundaries and is expressed by a range of tectono-morphological features. This study uses remote sensing to define tectonic structures and discriminate volcanic rocks linked to rifting within the basin using Landsat Enhanced Thematic Mapper Plus (ETM+) imagery. Prior to advanced image processing stages, images were corrected to eliminate atmospheric scattering effects and determine the best band combination for multi-spectral processing techniques based on statistical methods. Following pre-processing stages, edge detection filters were applied to derive tectonic structures defining the basin. The Brovey transformation, a statistical data merging method, was used to combine reflective multi-spectral bands with the Landsat ETM+ panchromatic band. This method fuses higher spatial data with data of lower spatial value. The western margin of the Karasu Basin is defined by the left-lateral Amanos Fault Zone with a contemporary motion (c. –0.4 mm a−1) probably accommodating most of the left-lateral strike-slip motion between Arabian and African plates on the northern continuation of the Dead Sea Fault Zone. The rift zone has been the site of extensive recent volcanism concentrated within the Brunhes Chron (<0.78 Ma) and linked to fault block rotations between the intracontinental master faults. The boundaries of this activity are defined here using a regolith mapping technique.

Indication of geohazard risk and economic value of gypsum deposits in the Tertiary Sivas Basin (Turkey) using ASTER and Landsat ETM+ images

The Tertiary Sivas Basin contains widespread, tectonically deformed deposits of massive Oligocene gypsum. This unit is one of the most important factors controlling the tectono-stratigraphic evolution of the basin insofar as these deposits are interpreted as decollement levels. Sivas Basin also has remarkable structural expressions within these evaporite deposits, as seen in satellite images aided by colour composites. Because of the arid climatic conditions of the region, the basin provides ease of interpretation geologically in terms of the synoptic-view capability of broad-band multispectral data sets, such as ASTER and Landsat ETM+. In this study, data fusion and decorrelation stretching methods were applied to highlight Oligocene gypsum deposits of the basin. These continental deposits host celestite and barite mineralization of great industrial importance. These gypsum deposits also carry a geohazard impact, namely their propensity to lead to collapses, particularly on the eastern side of the city of Sivas. Because the present study aids in the discrimination of these gypsum occurrences from other geological units, it may also lead to geohazard-risk reduction.