Storm-modulated ichnofabrics and taphonomic windows: Synergistic archive for Upper Miocene shallow-marine dynamics (Dar Pahn Unit, Iran)

The Upper Miocene Dar Pahn Unit (Makran accretionary wedge, SE Iran) integrates sedimentological, ichnological, and taphonomic analysis of a storm-dominated shallow-marine system. Progradational-retrogradational cycles (offshore marlstones FA1, offshore-transition heterolithics FA2, shoreface sandstones FA3) reflect relative sea-level fluctuations. Six taphofacies (TF1–TF6), from storm-reworked Pecten beds to pristine Dosinia assemblages and firmground Thylacodes , resolve preservation biases along depositional gradients controlled by energy and substrate stability. Concurrent ichnofabric successions ( Sc-Pl → Th-Di → Di-Ro ) track benthic responses to environmental stress, from dysoxic conditions to high-energy physical disturbance. Thalassinidean shrimp burrows serve as key stratigraphic proxies: large Thalassinoides ( lTh ) networks mark peak ecosystem engineering in organic-rich settings, while morphotypes ( Th. horizontalis vs. Th. suevicus ) reflect substrate-specific adaptations to firmground development. This study establishes thalassinid burrow diversity and their burrow size and complexity as a proxy for substrate evolution, energy regimes, sequence stratigraphy, and offering tools to reconstruct benthic ecosystem resilience. The dominance of thalassinidean shrimps as ecosystem engineers underscores their role in sediment mixing, organic matter cycling, and habitat modification. By bridging taphonomic biases with ichnological proxies, this work advances predictive models for ancient and modern storm-dominated systems, offering tools to decode depositional histories, faunal resilience, and stratigraphic architecture in shallow marine environments.