Autogenic factors display a main influence on the stacking pattern and formation of the HST deposits and related parasequences, characterized by middle-inner ramp associations developed at the upper part of the Tirgan Formation. The allogenic factors mainly affected the stacking pattern and parasequence development of the TST deposits at the lower part of the formation, characterized mainly by the deep ramp association. The development of the depositional sequence and parasequences of the studied successions of the Tirgan Formation were controlled by interactions between allogenic (tectonic and eustasy) and autogenic factors (wave and tidal hydrodynamic regimes). A third order depositional sequence including a transgressive system tract (TST) and a highstand system tract (HST) was also identified, along with several medium- and small-scale, thickening-shallowing upward cycles (parasequences). The deep ramp sediments feature a thick package of shales intercalated with thin-bedded bioclastic limestones and sandstones, indicating a low energy and stable sedimentary environment below the FWWB, which is periodically influenced by storm-induced waves. The shallow inner ramp association of facies is characterized by high diversity and abundance of bioclasts and trace fossils, highly fragmented and disarticulated fossils, local, sharp-based shell concentrations (tempestite) and cross-beds, current/wave ripples and horizontal lamination, altogether indicating the availability of light, nutrients, and oxygenation as well as high energy conditions in a wave-dominated, shallow marine setting. The shoal association -characterized by medium to thick-bedded limestone with well-sorted, grain-supported facies and special sedimentary structures such as sigmoidal tide bundles, bi-directional cross-beds and current ripples- displays a highly hydrodynamic, tide-dominated shallow marine setting above a fair weather wave base (FWWB). The tidal and lagoon sediments are characterized by low diversity and an abundance of skeletal elements, indicating a highly stressed depositional setting (e.g.
Fourteen facies were identified in the studied sequences, here grouped into five facies associations according to the depositional setting: tidal flat (Facies A), lagoon (Facies B), shoal (Facies C), shallow inner ramp (Facies D) and deep inner ramp (Facies E). The carbonate-dominated successions of the Tirgan Formation (Barremian-early Aptian) in the Kopet-Dagh Basin (Iran) were studied to decipher the tectonic and eustatic sea-level effects as well as the autogenic influence on lateral and vertical facies changes, depositional environment, and sequence stratigraphy of the tide-wave dominated sediments at the northern margin of the Neo-Tethys Ocean. The shallow open-marine association (FD), developed in the thin-to medium-bedded limestones, shows a high abundance and diversity of fossils, thus normal marine conditions (e.g., water circulation, nutrient supply, normal salinity) favouring high productivity and epifaunal colonization (e.g., Bachmann & Hirsch, 2006 Kietzmann et al., 2014 Ol oriz, Reolid, & Rodríguez-Tovar, 2006 Pomar et al., 2012 Sharafi et al., 2020 Wilmsen, Fürsich, et al., 2010, Wilmsen, Niebuhr, et al., 2010. HST, highstand system tract mfs, minor flooding surface Mfs, major flooding surface SB, sequence boundary TS, Transgressive surface TST, transgressive system tract distinctive depositional system (e.g., Baniak et al., 2014 Catuneanu, 2006Catuneanu,, 2019 Folkestad & Satur, 2008 Fürsich et al., 2009Fürsich et al.,, 2018Long & Yip, 2009 Moosavizadeh, Zand-Moghadam, & Rahiminejad, 2020 Neto & Catuneanu, 2010 Plink-Björklund, 2019 Pomar et al., 2012 Yoshida, Steel, & Dalrymple, 2007 Zecchin & Catuneanu, 2013). Allogenic-autogenic interplay in a sedimentary basin leaves evidence in terms of sediment composition, grain size, geometry and thickness of the sedimentary layers, bedding contacts, stacking pattern of the sedimentary packages, and ultimately in the development of a F I G U R E 1 4 Lithostratigraphic column, sedimentary environments, smalland medium-scale cycles, and depositional sequence of the Tirgan Formation in the Gorgoreh section (see Figure 12 for symbols).
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