Depositional environment of Jurassic sandstone lithofacies in the northern part of the Sanandaj- Sirjan; a case study ineast of Hamedan

Jurassic sandstone lithofacies of eastern Hamedan which overly on phyllite and slate facies of Triassic-Jurassic with an erosional unconformity or fault contact, represent similar characteristics with Shemshak type sediments in Central Iran. The study area is located in northern part of the Sanandaj-Sirjan sedimentary basin. In this study, sedimentary environments and facies of Jurassic sandstones [in this region] are interpreted. The studied section comprises 5 lithologies which fall into three assemblages: 1- lower unit (shale and siltstone), 2- middle unit (sandstone and sandy limestone) and 3- upper unit (sandstone). Based on lithology and structure, the lower unit formed in a lagoon environment. Existence of reworked open marine fossils the mid unit and hummocky cross stratification, swaly cross stratification, ichnofacies (Thalasinoides and Diplocratarion) in the upper unit, mainly composed of fine Quartzwacke, indicate a shallow- wave dominated marine environment.