The closure of the Palaeo-Tethys Ocean and the resulting Cimmerian orogeny played a pivotal role in shaping the Mesozoic geological evolution of the Tethyan realm. Nevertheless, the palaeogeographic and palaeoclimatic conditions associated with this tectonic transition - particularly within structurally complex regions such as the Aghdarband tectonic window in northeastern Iran - remain insufficiently constrained. To address this gap, the present study examines the Late Triassic shales of the Miankuhi Formation from the southern margin of the Turan Plate, aiming to refine the regional palaeoenvironmental reconstruction and provide new insights into the tectonic and climatic evolution during this critical interval. Our geochemical data reveal that the interactions between different tectonic regimes and climatic systems have profoundly influenced the region. The Miankuhi Formation was developed during an active tectonic setting. The shale sediments originated from felsic to intermediate source rock(s) under humid and warm climatic conditions and intense chemical weathering. These results correspond to the subduction of the Palaeo-Tethys Ocean beneath the south margin of Eurasia and the onset of the Cimmerian orogeny. These tectonic events led to a sea-level fall and a deltaic environment with anoxic to suboxic environment in the depositional basin of the Miankuhi Formation at tropical and subtropical latitudes.

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