Factors controlling stratal pattern and facies distribution of fluvio‐lacustrine sedimentation in the Sivas mini‐basins, Oligocene (Turkey)

Abstract

The Sivas Basin, located in the Central Anatolian Plateau of Turkey, is a foreland basin that records a complex interaction between sedimentation, salt tectonics and regional shortening during the Oligo-Miocene leading to the formation of numerous mini-basins. The Oligocene sedimentary infill of the mini-basins consists of a thick continental succession, the Karay€ un Formation, comprising a vertical succession of three main sub-environments: (i) playa-lake, (ii) fluvial braided, and (iii) saline lacustrine. These sub-environments are seen as forming a large Distributive Fluvial System (DFS) modified through time as a function of sediment supply and accommodation related to regional changes in climate and tectonic regime. Within neighbouring mini-basins and despite a similar vertical stratigraphic succession, subtle variations in facies assemblages and thickness are observed in stratigraphic units of equivalent age, thus demonstrating the local control exerted by halokinesis. Stratigraphic and stratal patterns reveal in great detail the complex interaction between salt tectonics and sedimentation including different types of halokinetic structures such as hooks, wedges and halokinetic folds. The regional variations of accommodation/sediment supply led to coeval changes in the architectural patterns recorded in the mini-basins. The type of accommodation regime produces several changes in the sedimentary record: (i) a regime dominated by regional accommodation limits the impact of halokinesis, which is recorded as very small variations in stratigraphic thickness and facies distribution within and between mini-basins; (ii) a regime dominated by localized saltinduced accommodation linked to the subsidence of each individual mini-basin enhances the facies heterogeneity within the DFS, causing sharp changes in stratigraphic thickness and facies assemblages within and between mini-basins.Correspondence: Charlotte Ribes, Laboratoire des Fluides Complexes et leurs R eservoirs,

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

“…A synthetic stratigraphic column, showing the sequence seen in the Sivas Basin, is proposed (Figure ). It is based on a compilation of numerous publications and a recent reevaluation of the stratigraphic evolution [ Kurtman , ; Poisson et al ., ; Çiner et al ., ; Ribes et al ., , ].…”

“…The Sivas Basin provides very good exposures of many evaporite‐related geometries and minibasins due to their tilting that allow the study of salt tectonic processes in great detail [e.g., Ringenbach et al ., ; Callot et al ., ; Ribes , ; Ribes et al ., ; Kergaravat , ]. Previous studies have focused on the sedimentary and geometrical record of salt tectonics along minibasin flanks and revealed a possible influence of regional shortening responsible for tilt of some minibasins which can locally become vertical [ Ribes et al ., ; Ribes et al ., ].…”

3D modeling from outcrop data in a salt tectonic context: Example from the Inceyol minibasin, Sivas Basin, Turkey

“…At the end of the Eocene, a huge accumulation of marine evaporitic deposits occurred in the Sivas Basin. Minibasins exhibit several salt tectonic structures, such as halokinetic sequences, resulting from the interplay between sediment accumulation and salt flow (Ribes et al, , 2016Kergaravat, 2016). Striking evidences of such halokinetic structures are well-observed in the central part of the Sivas Basin, which exhibits a typical wall and basin structure (WABS) characterized by minibasins surrounded by polygonal network of evaporite walls and welds (Ringenbach et al, 2013;Callot et al, 2014;Ribes et al, 2015Ribes et al, , 2016Kergaravat, 2016).…”

“…Thus, we completed the field data set with interpretive cross sections of the minibasin, illustrating the conceptual geometries at depth. Their geologic interpretations are based on the observation of similar structures imaged by seismic data (Ringenbach et al, 2013) and on our local knowledge of halokinetic structures in the Sivas Basin (Ringenbach et al, 2013;Callot et al, 2014;Pichat et al, 2015;Ribes et al, 2015Ribes et al, , 2016. Interpretation lines were digitized from this section and then used as a guide for the 3D model construction ( Figure 6).…”

The Pre‐Obduction to Post‐Obduction Evolution of the Sivas Ophiolite (Turkey) and Implications for the Precollisional History of Eastern Anatolia

“…The latest Eocene to Oligocene deposits record the transition from marine to continental depositional environments associated with sedimentation of widespread evaporitic sequences (Figure b). The post‐Oligocene evolution of the Sivas Basin is characterized by important salt tectonic activity well developed in its central and northern parts (Callot et al, ; Kergaravat, ; Kergaravat et al, ; Kergaravat et al, ; Legeay, ; Legeay, Pichat, et al, ; Legeay, Ringenbach, et al, ; Pichat, ; Pichat et al, ; Pichat et al, ; Ribes, ; Ribes et al, ; Ribes et al, ; Ribes et al, ; Ringenbach et al, ).…”