Alexandre Pichat

• Phd -Geoscientist
• TotalEnergies

The Zechstein Group in the Northern Permian Basin (UK and south Norway sectors of the North Sea) is subdivided into four halite-rich evaporitic sequences. These sequences contain K-Mg salts, the amount and distribution of which are still poorly constrained. Understanding the lithological variations of the evaporites is important for understanding t...

During the Early Cretaceous, massive evaporite accumulations formed in the opening South Atlantic. However, the evaporite depositional model is still poorly constrained at the scale of the West African margin. The present study focuses along the proximal domain of the south Gabon - Congo - Cabinda margin and is based on (i) log interpretations of 2...

Deciphering past salt tectonics events is often difficult in orogenic domains. The southwestern Alpine foreland in France presents a long Mesozoic extensive salt tectonics history, inverted during the Cenozoic Alpine orogeny. Syn-orogenic Cenozoic salt-related deformations are rather difficult to identify because of the contemporaneous shortening e...

Halokinetic deformations synchronous with salt deposition are processes already suggested in several salt giants including the Lower Cretaceous salt deposits of the Santos Basin in Brazil. However, the dynamics of syn-depositional deformation has never been studied in a coherent depositional and structural framework. This study investigates well da...

The European Alps result from the closure of a former Triassic to Cretaceous rifting system in which significative accumulation of Upper Triassic salt deposited. The thickness and spatial distribution of these salts had a major impact on the morphology and dynamic of the Alpine orogen all over the Western Alps. Following a bibliographical review, f...

The 1 km thick evaporitic Permian Zechstein group in the Netherlands is subdivided into 5 halite rich evaporitic sequences including K–Mg salts (polyhalite, kieserite, sylvite, carnallite and bischofite) for which the position in the Zechstein stratigraphy is still poorly constrained. Understanding the repartition of K–Mg salts is especially import...

Inherited and syn-compressional salt-controlled structures in orogens are difficult to distinguish from compressional features because classical salt features (halokinetic growth strata, salt welds) can be misinterpreted as shortening-related structures (syn-kinematic growth strata, tectonic unconformities). In the Sivas basin in Turkey, syn-kinema...

The evaporites of the Aptian Loémé Formation occur along the stable structural domain of onshore Congo as horizontally well-stratified depositional halite interbedded with Mg-poor potash minerals including carnallite, bischofite, tachyhydrite and sylvite. Eleven correlative depositional recharge-to-evaporation cycles are composed of suites of organ...

Recent studies in the Southern Subalpine Chains in France have documented a variety of salt related geometries including allochthonous salt sheets of Upper Triassic evaporites, which have develop at different stages of the Alpine history (e.g. Graham et al., 2012). Such allochthonous salt sheets are common features both in salt-bearing passive marg...

The E-W oriented Sivas foreland basin in Turkey recorded a salinity crisis during the Late Eocene resulting in evaporite accumulations thick enough to trigger intense halokinesis during the Oligo-Miocene. The salinity crisis is studied thanks to three sedimentological sections crossing the transition from the last marine deposits (Bözbel Formation)...

Folder kmz (Virtual Fieldtrip on Google Earth with Elevation Exaggeration = 1) with the geolocation of the main analyzed field localities, geological maps, and cross-sections from the Structure and kinematics of the Central Sivas Basin (Turkey): salt deposition and tectonics in an evolving fold-and-thrust belt. Assembled by Cristina Biete & Cristin...

The Sivas Basin in Turkey displays in its central part an Oligo-Miocene halokinetic province which acts as a major outcrop analogue to study salt-sediment interactions. Based on field geology observations, the present paper focuses on the geometry and sedimentology of several minibasins having the particularity of being mainly filled by gypsiferous...

The Sivas Basin in central-eastern Anatolia, is a north-verging fold-and-thrust belt with syn-orogenic salt tectonics. It formed above the northern leading edge of the Tauride platform, the Kırşehir micro-continent, the edge of the Pontide arc and the related ophiolitic suture. We revised the entire tectonostratigraphy of the central Sivas Basin to...

The Sivas Basin in central-eastern Anatolia is a north-verging salt-bearing fold-and-thrust belt including synorogenic salt tectonics. It formed between the northern leading edge of the Taurides platform and the Kırşehir block since Late Cretaceous time. We have constructed five regional cross-sections supported by field data and 2D seismic to con...

This study includes a revised stratigraphy and cross-sections of the 1/50.000 scale geological map of the Sivas Basin with the aim of revealing analogies with the evaporitic units in the Gulf of Mexico. The study area is spread over an area of approximately 10,000 km2 and can be divided into three different structural areas from south to north by c...

Georeferenced map (geoTIF) of the Central Sivas Basin

Geological map of the Central Sivas Basin (A0 format)

Cross-sections and correlations logs of the Central Sivas Basin (A1 format)

This paper presents a revised geological map at the 1/50,000 scale of the Central Sivas Basin together with a synthetic stratigraphic chart and cross-sections. The map covers an area of approximately 9840 km² within the Eastern Anatolian orogen. The structure of the studied area is dominated by three major tectonic domains: (i) to the south, a nort...

The isotopic composition of evaporites can shed light on their environment of precipitation and their subsequent recycling processes. In this study, we performed Sr, O and S isotopic analyses on evaporitic sulphates in the halokinetic Sivas Basin. The main objectives were to decipher the age and origin of the evaporites responsible for the salt tec...

The Sivas Basin in central-eastern Anatolia, is a north-verging fold-and-thrust belt involving Late Cretaceous to Neogene sediments. It belongs to a group of Anatolian basins that developed after the northern Neotethys closure. The Sivas Basin formed above the northern leading edge of the Tauride platform, the Kırşehir micro-continent, the edge of...

This manuscript focuses on the various evaporitic systems of the Sivas Basin (Turkey) and assesses the diagenetic impact of saline fluid flow on siliciclastic reservoir analogues. This study takes place in a foreland basin that has the peculiarity of having recorded halokinetic deformations, as evidenced by outcropping Oligo-Miocene mini-basins str...

The Alboran Domain, situated at the western end of the Mediterranean subduction system, is characterized by the Ronda Peridotites, one of the world largest exposures of sub continental mantle. Using U-Pb (LA-ICP-MS) and Ar-Ar dating, we precisely dated two tectonic events associated with the Tertiary exhumation of the Ronda Peridotites. First, shea...

We propose a 3D modelling strategy of the encased mini-basin of Inceyol in Sivas (Turkey). The challenge lies in the combination of sparse outcrop data and the complex interpretive geometry of geological structures that comes from salt tectonics. We succeeded in modelling the convoluted salt surface using an explicit indirect surface patch construc...

The recent discovery of Oligo-Miocene salt-walled continental mini-basins in the Sivas Basin (central Anatolia, Turkey) provides the opportunity to unravel the influence of halokinesis on the diagenesis of continental mini-basin infilling. In this study, petrographic and geochemical analyses are used to define the diagenetic sequences recorded by t...

The Sivas Basin is located in a particular position at the junction of three crustal domains: the Pontides to the North, the Anatolide-Tauride platforms to the South, and the Central Anatolian Crystalline Complex to the West. This Tertiary basin is formed during the closure of the Northern branch of Neotethys. In regard to subsurface data, this bas...

The Oligo-Miocene Sivas basin (Turkey) is strongly affected by salt tectonics, best expressed in its central part. Halokinesis initiated from the Upper Eocene Hafik formation, composed of thick evaporite layers. Salt tectonics induced the formation of numerous mini basins filled with continental to marine deposits, and nowadays separated by diapiri...

The Oligo-Miocene Sivas basin (Turkey) is strongly affected by salt tectonics, best expressed in its central part. Halokinesis initiated from the Oligocene Hafik formation, composed of thick evaporite layers. Salt tectonics induced the formation of numerous mini basins filled with continental to marine deposits, and nowadays separated by diapiric g...