Salt tectonics in the Sivas basin (Turkey): crossing salt walls and minibasins

Abstract

The Sivas basin (Turkey) shows pronounced salt tectonics activity involving the Oligocene evaporites. Despite the complete exposure of the structures, the tectonic evolution of the basin has been so far misunderstood because it has only been envisioned in a context of thrust tectonics. The core of the basin, a 35×25 km area, displays rounded minibasins separated by evaporitic walls, and partially covered by remobilized gypsum (either sedimentary or flowage). The minibasins are filled by Mid-Oligocene to Early Miocene clastics (fluvial silts and sandstones), marls, and lacustrine to marine limestones, the thickness of which may reach 4 kilometres. The stratal architecture along evaporite walls records the progressive subsidence of the minibasins, with strong rotation of beds, unconformities and local reworking of evaporites. Within the basin, the sediments show lateral thickness variations and spectacular angular unconformities. The observed geometries show striking similarities with the seismic data from petroleum basins suffering strong salt tectonism (gulf of Mexico, Precaspian basin, Angolan margin).

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

“…These studies demonstrate a large variety of halokinetic structures and highlight ambiguities in interpreting conventional seismic images (Fossen, 2010;Jackson et al, 2014). This knowledge strongly helps the interpretation of structures poorly imaged by reflection seismic data (Giles and Lawton, 2002;Jackson and Harrison, 2006;Ringenbach et al, 2013;Callot et al, 2014). They are the only way to get a direct 2D observation of many subseismic evaporite-related geometries.…”

“…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).…”

Paleomagnetic constraints on the timing and distribution of Cenozoic rotations in Central and Eastern Anatolia

“…Salt mobility led to strong local deformation and the formation of mini-basins (Callot et al, 2014;Kergaravat et al, 2016;Pichat et al, 2016;Poisson et al, 2016;Ribes et al, 2015). In the west, upper Miocene to recent volcanic rocks are found close to the EFZ and its connection to the Sivas fold-andthrust belt (Cater et al, 1991;Poisson et al, 1996;Yilmaz and Yilmaz, 2006).…”

Depositional stages of the Eğribucak inner basin (terrestrial to marine evaporite and carbonate) from the Sivas Basin (Central Anatolia, Turkey)

“…In this area, Cenozoic units commenced with massive gypsum formed as a transitional level from the Eocene to Oligocene (Hafik Formation: Kurtman, 1973) and upward, it grades into Oligocene sediments displaying lateral and vertical facies changes and different environmental conditions. The study area is considered as the Eğribucak inner basin (sensu stricto mini basin: Ringenbach et al, 2013;Callot et al, 2014;Poisson et al, 2015;Ribes et al, 2015) because of limited extension of lithological units and an isolated character from the neighboring depositional systems within the Sivas Basin. The evaporites exposed in the Eğribucak succession have been determined in various environments attributed to different ages ranging from early Miocene to middle Miocene (Table 1).…”

“…The late Eocene regression-associated tectonic activity constrained the basin-range upliftings that divided the basin into subbasins such as Akçakışla-Düzyayla, Şarkışla-Celalli, and Akkışla-Altınyayla (Cater et al, 1991;Yılmaz and Yılmaz, 2006). The Eğribucak area was previously determined as a minibasin that resulted from salt tectonism or a diapir-bounded local basin (Ringenbach et al, 2013;Callot et al, 2014;Poisson et al, 2015;Ribes et al, 2015). Environmental and lithological correlations are very difficult to establish between these inner/minibasins due to their own depositional characters.…”