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 north-verging thrust wedge involving Maastrichtian – Eocene sediments deposited onto an ophiolitic basement, (ii) in the center an Oligo-Miocene domain shaped by salt tectonics detached above the thrust wedge, along a late Eocene salt layer, and, (iii) to the north the Pliocene depocenter onlapping onto the Kırşehir basement. The central halokinetic domain exhibits two generations of minibasins (respectively, early Oligocene and late Oligocene to late Miocene), separated by an evaporite canopy. The map includes new stratigraphic correlations for the pre-salt stratigraphy and improve the comprehension of the southern fold-and-thrust-belt.

Number of dismembered ophiolite bodies crop out between Sivas and Malatya on the top of the Eastern Tauride platform in the central-eastern Turkey. One of which at the southern margin of the Sivas basin in the Tecer Mountain area comprises melange and the lower part of an oceanic lithospheric section on top of the Tauride platform. The mantle tectonites are characterized by variably serpentinized harzburgites and dunites, and are intruded by numerous isolated dykes. The gabbroic cumulates consist of olivine gabbro, gabbro and gabbronorite. The major and trace element geochemistry of the mafic cumulate rocks suggests that the primary magma was compositionally similar to those observed in modern island-arc tholeiitic sequences. The isolated dykes are exclusively basaltic in composition and display geochemically two distinct subgroups: Group I is represented by high TiO2 (.87–1.47 wt.%) and other incompatible elements, whereas Group II is characterized by low TiO2 (.36–.66 wt.%) and other incompatible elements. The Group I isolated diabase dykes have flat to slightly LREE-depleted profiles (La/YbN = .32–.79), whereas the Group II isolated diabase dykes are more depleted in general and have a LREE-depleted character (La/YbN = .19–.49). This suggests that the isolated dykes were derived from an island arc tholeiitic magma (Nb/Y = .02–.05) with different degrees of partial melting (Group II > Group I) and relatively high oxygen fugacity in intra-oceanic subduction zone. The ophiolitic rocks in the study area may well be compared with the Divriği ophiolite to the southeast. All the evidence suggests that the isolated dykes in the Tecer Mountain area differ from the alkaline isolated dykes cutting the Divriği ophiolite. Since the late stage dykes (~76 Ma) in the Divriği area are alkaline, the tholeiitic isolated dykes in the present study should have been emplaced prior to the alkaline dykes during Late Cretaceous SSZ-spreading (~90 Ma) within the Inner Tauride Ocean.

We present here a reappraisal of the tectonic setting, stratigraphy and palaeogeography of the central part of the Sivas Basin from Palaeocene to late Miocene. The Sivas Basin is located in the collision zone between the Pontides (southern Eurasia) and Anatolia (a continental block rifted from Gondwana). The basin overlies ophiolites that were obducted onto Anatolia from Tethys to the north. The Central Anatolian Crystalline Complex (CACC) experienced similar ophiolite obduction during Campanian time, followed by exhumation and thrusting onto previously emplaced units during Maastrichtian time. To the east, crustal extension related to exhumation of the CACC created grabens during the early Tertiary, including the Sivas Basin. The Sivas Basin underwent several tectonic events during Paleogene–Neogene. The basin fill varies, with several sub-basins, each being characterised by a distinctive sequence, especially during Oligocene and Miocene. Evaporite deposition in the central part of the basin during early Oligocene was followed by mid-late Oligocene fluvio-lacustrine deposition. The weight of overlying fluvial sediments triggered salt tectonics and salt diapir formation. Lacustrine layers that are interbedded within the fluviatile sediments have locally yielded charophytes of late Oligocene age. Emergent areas including the pre-existing Sivas Basin and neighbouring areas were then flooded from the east by a shallow sea, giving rise to a range of open-marine sub-basins, coralgal reef barriers and subsiding, restricted-marine sub-basins. Utilising new data from foraminifera, molluscs, corals and nannoplankton, the age of the marine transgression is reassessed as Aquitanian. Specifically, age-diagnostic nannoplankton assemblages of classical type occur at the base of the transgressive sequence. However, classical stratigraphic markers have not been found within the planktic foraminiferal assemblages, even in the open-marine settings. In the restricted-marine sediments, there are rich planktic foraminiferal assemblages of classical type but these are of little use in stratigraphy. In contrast, the gastropod fauna indicate a Burdigalian age. Sediment reworking in the restricted-marine environments precludes stratigraphic determination. In such environments, micro- and nano-organisms experienced atypical developmental conditions. The small benthic foraminifera and associated ostracod assemblages are good indicators of salinity which varied considerably within the restricted-marine sub-basins. Some of the corals within the coralgal reefs barriers are also dated as Aquitanian. A combination of the salt tectonics and the late Miocene north-westward-verging thrusting created the present basin complexity.

The Sivas Basin, located on the Central Anatolian Plateau in Turkey, is an elongate Oligo-Miocene basin that contains numerous salt-walled mini-basins. Through field analysis, including stratigraphic section logging, facies analysis and geological mapping, a detailed tectono-stratigraphic study of the Emirhan mini-basin and its 26km thick sediment fill has been undertaken. Three main palaeoenvironments are recognized - playa-lake, braided stream and lacustrine - each corresponds to a relatively long-lived depositional episode within a system that was dominated overall by the development of a distributive fluvial system. At local scale, this affects the geometry of the succession and influences facies distributions within preserved sequences. Sequences affected by wedge geometries are characterized by localized channelized sandstone bodies in the area of maximum subsidence and these pass laterally to floodplain mudstone towards the diaper; several internal unconformities are recognized. By contrast, sequences affected by hook geometries display narrow and steep drape-fold geometries with no evidence of lateral facies change and apparent conformity in the preserved succession. The sediment fill of the Emirhan mini-basin records the remobilization of diapir-derived detritus and the presence of evaporitic bodies interbedded within the mini-basin, implying the growth of salt walls expressed at the surface as palaeo-topographic highs. The mini-basin also records the signature of a regional change in stratigraphic assemblage, passing from playa-lake facies to large-scale highly amalgamated fluvial facies that represent progradation of the fluvial system. The initiation and evolution of this mini-basin involves a variety of local and regional controls. Local factors include: (i) salt withdrawal, which influenced the rate and style of subsidence and consequently temporal and spatial variation in the stratigraphic assemblage and the stratal response related to halokinesis; and (ii) salt inflation, which influenced the topographic expression of the diapirs and consequently the occurrence of diapir-derived detritus intercalated within the otherwise clastic-dominated succession.

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 35x25 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).

This study is aimed to perform digital geologic mapping and ASTER image analysis around southeastern part of the Sivas Tertiary Basin. The interest area is located at the intersection of ENE-WSW oriented Deliler Thrust Belt and Tecer Fault Zone. Ophiolithic rocks which were belonging to Inner Tauride Ocean Suture belt were outcropped in a vast region. This region also forms the northern boundary of the Menderes-Tauride platform. Tectonostratigraphy of the region is represented by two different sedimentary sequences separated by Deliler Fault Zone. While a thick cover of Oligocene-Miocene continental unit was observed on the southern section of Deliler Fault Zone, Lower-Middle Eocene marine, Oligocene gypsum and Lower Miocene marine sediments were outcropped on the northern part of this belt. Late Miocene continental deposits were folded while Plio-Quaternary fluvial sediments were observed horizontally along the Deliler Thrust Zone. Within the context of this study, interested region was mapped digitally using tablet pc and ArcPad software. Using this software, areas of outcropping units, linear geologic map elements like faults and fold axes were recorded digitally during field studies and some database queries such as formation name, age, and lithologies were determined in terms of saving time and digitization efforts. Additionally, a number of image processing efforts were applied to 14 channels ASTER image of the region to highlight geological features such as lithological boundaries and structural components. Thus, a detailed digital geologic map was formed at the end of this search. Furthermore, a number of image processing studies were acquired supporting geological mapping at field.

Bu calisma, Sivas Tersiyer Havzasi’nin guney kenarini iceren Tecer Daglari guneyindeki bolgenin sayisal jeolojik harita alimi ve ASTER goruntuleriyle incelenmesini amaclar. Inceleme alani DKD-BGB dogrultulu Deliler Bindirme Kusagi ve Tecer Fay Zonu’nun kesistigi bolgede yer alir. Bolgede, Ic Torid kenet kusagina ait ofiyolitik kayaclar genis bir bolgede yuzeyler. Bu bolge ayrica Menderes-Toros Platformunun kuzey sinirina da karsilik gelmektedir. Bolgenin tektonostratigrafisi Deliler Fay Zonu tarafindan ayrilan iki farkli cokel istifi ile temsil edilir. Deliler Fay Zonunun guneydeki kesiminde ofiyolitik bir temel uzerinde yer alan kalin bir Oligo-Miyosen karasal istifi gozlenirken kuzeyde kalan bolumde ise Alt-Orta Eosen denizel cokelleri, Oligosen jipsleri ve Alt Miyosen denizel cokelleri yer almaktadir. Deliler Fay Zonu boyunca Gec Miyosen karasal cokelleri kivrimlanmaya ugramis, Pliyo-Kuvaterner akarsu cokelleri ise yatay olarak gozlenmislerdir. Bu calisma kapsaminda inceleme alani, tablet bilgisayar ve ArcPad yazilimiyla sayisal olarak haritalanmis; yuzeyleyen birimlerin alansal sinirlari, fay ve kivrim ekseni gibi cizgisel jeolojik harita unsurlari arazi calismalari sirasinda zamandan kazanilarak sayisal olarak kaydedilmistir. Buna ek olarak litolojik sinirlari ve yapisal bilesenleri ortaya cikarmak amaciyla bolgeye ait 14 bantli ASTER uydu goruntulerine goruntu isleme teknikleri uygulanmistir. Calisma sonucunda, arazi ve laboratuarda gerceklestirilen goruntu isleme calismalari yardimiyla bolgeye ait ayrintili bir jeolojik harita hazirlanmistir.

This work is aimed at differentiation of ophiolitic melange rocks which were outcropped 60 km far from Sivas city center using image processing and spectral measurement methods. These rocks are known as oceanic crust remnants which were made up of different rocks. Turkey hosts several paleo-oceans and their realms in Alpine-Himalayan orogenic belt. The Neotethyan ophiolites in Turkey are characterized by supra subduction zone (SSZ-type) ophiolites. Ophiolitic rocks are generally coloured with greenish tones and human eye could not separate these tone differences. But satellite images such as ASTER can realize these separation utilizing spectral enhancement methods such as classification and decorrelation stretching. Chromite is a valuable mineral and is formed in only ophiolitic rocks. Dunites and harzburgites named as also ultramafic tectonits of ophiolitic serie mainly contain these deposits in study area. In this study, an approach was also realized to find target regions of chromite deposits with the aid of spectral methods. Spectral measurements were realized to determine boundaries between different melange rocks using spectroradiometer. Reflectance curves collected from field and laboratory analysis were evaluated together and compared with ASTER image of the study area respectively. A detailed differentiation generally was accompanied with petrographic and geochemical analyses.

Apatite fission-track data indicate that the (circum)-central Anatolian granitoids (CAG) were exhumed during successive shortening phases following continent-continent collisions within the Neo-Tethyan domain in central and east-central Anatolia. The Early to Middle Paleocene exhumation of the CAG is thought to be a consequence of the collision between the Tauride-Anatolide platform (TAP) and the Eurasian plate (EP) following the consumption of the Izmir-Ankara-Erzincan strand of the northern Neo- Tethys. The Oligocene exhumation documented by the data for the Kosedag pluton in east-central Anatolia is considered to be related to the compression due to continuing convergence between the EP and TAP which seems also to be synchronous with the collision between the amalgamated EP and TAP and the Afro-Arabian plate following the consumption of the southern Neo-Tethys along the Bitlis suture zone in southeast Anatolia. The punctuated tectonic exhumation of (circum)-CAG is correlated in space and time with the formation and infilling of the central Anatolian foreland basins. The formation and rapid infilling reflects fast erosion, balancing the uplift of basement rocks including the central Anatolian granitoids.

The Niksar Basin is sited along the eastern segment of the North Anatolian Fault Zone in Turkey. It is a young sigmoidal pull- apart basin bordered by two non- parallel master faults associated with earthquakes in 1939 and 1942. The fault geometry along the irregular ENE margin of the basin is complex where young Plio - Quaternary volcanic rocks reach the surface along pairs of steep strike- slip faults which cut the basin sediments. The volcanic rocks around the Niksar Basin have been dated by high precision K- Ar dating and the ages range between 542 +/- 9 ka and 567 +/- 9 ka. The lavas are mainly alkaline ( sodium dominated) in nature and include basaltic trachandesite ( mugearite) and trachyandesite ( benmoreite) with minor sub- alkaline compositions of dacitic andesite, rhyodacite and rhyolite. Despite the large compositional gap between basaltic and felsic lavas, major and trace element distributions indicate that both the basaltic and felsic lavas are cogenetic. Abundances of major oxides and trace elements vary systematically through this compositional spectrum. Fractional crystallization of the observed phases accounts for the diversity of intermediate and evolved products. Amphibole fractionation in basalts at depth causes the trend towards silica saturation while alkali feldspar fractionation dominates the final stages of crystallization. Significant crustal contamination has occured in the evolved magmas but contamination is generally minimal or absent in their basaltic parents.Alkaline basaltic rocks have OIB ( ocean island basalt) like trace element patterns characterized by enrichment in LILE, HFSE, LREE and slight depletion in HREE relative to primitive mantle values. Overall geochemical variations indicate the combined effects of different degrees of partial melting, fractional crystallization and variable degrees of crustal contamination.