The Late Devonian was a period of drastic environmental changes, as exemplified by a major biotic crisis at the Frasnian–Famennian boundary (FFB) and the onset in Famennian times of glaciations across southern Gondwana. Worldwide evidence for the coeval development of the major Acadian–Eovariscan belt led us to propose a model relating the Late Frasnian–Famennian environmental perturbations to extensive continental uplift through two atmospheric CO2‐depleting mechanisms: (1) the intensification of silicate weathering on the continental areas as attested by a major rise in the 87Sr/86Sr composition of sea water at the FFB; and (2) the massive burial of organic carbon (Kellwasser events) in partially confined basins due to the collisional‐induced reduction of equatorial oceanic communications between the Palaeotethysian and Panthalassic oceans. This process is also suggested to have been controlled by an important primary productivity connected to an increased nutrient availability triggered by the enhanced continental run‐off.

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The Padeha Formation in the Eastern-Alborz Mountains (northeast Iran) is an Early to Middle Devonian syn-rift succession. Siliciclastic rocks (conglomerates, sandstones, mudstones, and red paleosols) to non-marine carbonates (yellowish calcretes, dolocretes, stromatolites, and sandy bivalve packstone) associated with volcaniclastic rocks (basalts or andesites and tuVs) are present in this succession. Facies analysis led to the recognition of three facies associations that are deposited in three terrestrial environments (alluvial fan, distal fan, and palustrine/lacustrine). Its sedimentary Wll pattern and association with maWc volcaniclastic rocks indicate that this formation is related to the initial phase of a rift basin (intracratonic rift). Paleosols of this formation are good indicators for recognition of paleoenvironmental factors (climatic changes from semi-arid to sub-humid with annual Xuctuation, small and short gross-like vegetation cover, subaerial exposure, very shallow lake, volcanic source rocks, and early meteoric diagenesis).

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