Tectono-stratigraphy of western Yazihan (Malatya)

Tectono-stratgraphy of some part of the Yazıhan-Hekimhan basin within the eastern Tauride system around Yazıhan and its surroundings area have been investigated in this study. Various formations ranking in age from Upper Jurassic to Quaternary are observed in the area.Upper Jurassic-Lower Cretaceous age Horasançal formation which mainly made up of micritic and partly dolomitic limestone deposited in outer shelf form the basement rock unit of the area. Hocalıkova ophiolites which probably thrusted into the area from North to the South during and after late Campanian tectonically overlie the Horasançal formation. Hekimhan formation transgresivelly deposited during late Campanian-early Maastrichtianaround the tectonically controlled basin to the edge of the basin (shallow marine-shore line sediments). Hekimhan formation was deposited partly in a fluvial-delta and partly very shallow marine environments at the base (Kesikköprü member) and shallow marine-reefal environments to the top (Karatepe and Kızılkaya members). Palaeocene age Medik formation, which mainly made up of mudstone intercalated pebblestone of alluval fan deposits, overlies this unit with angular unconformity to the South of the basin. Middle-Upper Eocene age Tohma formation that generally was deposited in lagon, beach and shelf environments comprising mainly pebblestone, sandstone, limestone-marl rests on the Medik formation with an angular unconformity. This unit is cut and unconformably covered by volcanic activity of Upper Eocene Leylek volcanics that contains andesite and trachiandesite. Aquitanian age Çavuş formation, which was deposited in shallow marine (shelf) environment comprising mainly detrital limestone, rest unconformably on the volcanics. Burdigalian age Ansurçay formation, which was deposited in shallow marine (open shelf) conditions comprising mainly detrital limestone, marl and reef limestone, rests on the Çavuş formation with angular unconformity. Lower Miocene age Akyar formation which starts with basal conglomerates and mainly made up of mudstone-sandstone and tuff-limestone alternations, overlies the Ansurçay formation with angular unconformity. Middle-Upper Miocene age Yamadağ volcanics comprising mainly basalts unconformably rests on the Akyar formation. Middle Miocene age Parçikan formation, which deposited in a lacustrine settings presenting soft sediment deformations indicating tectonically active areas, are seen on the Yamadağ volcanics. Plio-Quaternary age Mısırdere formation, which was deposited in alluvial fan and braided river enviroments comprising mainly pebblestone, sandstone, and mudstone alternations, rest on the Parçikan formation. Quaternary age alluvial fan, terrace and alluviums are the youngest sediments of the area and unconformably rest on all the older units.According to investigated and determined stratigraphy; 2 different transgressive stage can be distinguished. First stage; crustal thikness increased during the emplacement of Hocalıkova ophiolites during the late Maastrichtian, thus, some terrestrial areas appeared within the marinal basin due to uplifting. Due to affects of tensional forces at this stage a basin was opened to the north of Yüksekova-Baskil arc (ensialic) at the back arc area, this basin got matured during late Maastrichtian and the basin started to close during middle Eocene, this was followed by developement of terrestrial volcanism (Leylek volcanics) which is the end of first transgressive stage. By the end of the closing stage of the basin during Oligocene, the area totally turn into the terrestrial environment conditions where the pebbles of Leylek volcanics are observed at the basal part. The second transgressive stage started by the end of the Oligocene, thus, some areas turned into shallow marine and partly into the lacustrine setting environments. The affects of left lateral strike-slip Malatya Fault Zone from Early to Middle Miocene up to the recent period are observed within the young sediments. Particularly, soft sediment deformation structures were formed in the late Miocene and Pliocene sediments. Also, local depression and uplifting areas were formed due to transtensional and transpressioal movements formed during late Miocene along the Malatya Fault Zone that limits the basin. At this stage, lacustrine sediments, which was deposited at the depression areas formed by the affects of transtension away from the marine areas along the fault zone, started to ealuate (Parçikan formation). Presence of Plio-Quaternary terrestrial sediments represent the end of the second transgressive stage.