The thick Jurassic fluvial coarse-grained sediments rest non-conformably on older metamorphic rocks to the northwest of Mashhad. Two sections, 300 and 400 m thick, were measured and studied through the Jurassic deposits. In this unit, three facies assemblages,conglomerate, sandstone and shale, have been identified. They comprise eight lithofacies (Gcm, Gmg, Gmm, Sm, Sh, Sp, Fl, and Fm) and four architectural elements (Channel-fill element (CH), Sediment gravity flows (SG), Downstream–accretion element (DA), and Overbank fines (FF)). The orientation of the gravel particles indicates that the direction of the paleo-flow was from northeast to southwest. The presence of an erosive base, lens-shaped sediment bodies, and fining-upward sequences suggests a gravelly braided-river system that deposited in a half-graben. Based on the results of petrological studies, subarkose, arkose, lithic

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