Interpretation of depositional environment, sequence stratigraphy and provenance of Neogene deposits eastern Kopet-Dagh and east of Central Iran

In this study، Neogene deposits of eastern Kopet-Dagh and east central Iran have been investigated. These deposits in the eastern Kopet-Dagh Basin consist of two lithofacies associations including gravelly (Gcm، Gmm، Gmg، Gh) and sandy (Sm) that form within four structural elements (SG، GB، SB، CH). From base to up، they were deposited in the braided river with sandy bed load in the alluvial fan depositional systems near the source area. Sequence stratigraphic analysis of Neogene deposits، based on lithofacies variations، indicated that these sediments formed in an area with the low accommodation space. Petrography study indicates that they were derived from collision and recycled orogen tectonic setting. Neogene deposits in the studied area in the east Central Iran are composed of four lithofacies associations including gravelly (Gcm، Gmm، Gmg، Gh، Gt، Gp)، sandy (Sm، Sh، St، Sp)، fine grain (siltstone) (Fm) and evaprite (P) that formed within five structural elements including SG، GB، SB، CH، FF. These sediments، from base to up، were deposited in playa and proximal to mid sandy-gravelly bed braided river in alluvial fan depositional systems. Sequence stratigraphic analysis indicates that these deposits consist of two sedimentary sequences. The first sequence belongs to high accommodation space and the second one formed during the low accommodation space. Sandstones and conglomerates composition as well as tectonic position of area indicate that the tectonic settings of the source area was probably arc orogen and continental block.