Synchronizing Tethyan paralic and deep-water paleoclimatic evidence during Cretaceous Oceanic Anoxic Events. The high-resolution δ13C chemostratigraphy of the Pietraroja wetland Lagerstätten (lower Albian, Southern Italy): A tale of the evolving OAE1b

Highly resolved stratigraphic correlations enhance our understanding of how terrestrial and marine ecosystems tracked the evolving Earth, including the development of Cretaceous Oceanic Anoxic Events (OAEs) and Red Beds. However, the interplay of climatic-paleoenvironmental factors governing major facies changes during mid-Cretaceous OAEs and ORBs remains elusive, hindering detailed cause-and-effect reconstructions. Using high-resolution carbonate carbon chemostratigraphy, we compare the early Albian dynamics of the Apennine Carbonate Platform (ApCP) and coeval basins in the Mediterranean Tethys, across the regional humid-arid belt boundary. The δ13C signature of the paralic ApCP Pietraroja section highlights that the Middle (fish- and plant-rich) and Upper (terrestrial vertebrate-rich) Lagerstätten were coeval with the OAE 1b Paquier black shales and the HN10-HN11 markers of the Vocontian Basin, respectively. Astrochronological tuning of the Pietraroja δ13C signature implies that the Middle Lagerstätte reflected a millennial-scale hydroclimatic shift and a 60 kyr-long hiatus just above the ApCP Paquier equivalent. The Middle Lagerstätte was deposited in an arid wetland turning wetter, whereas the Upper Lagerstätte in a moist paralic context. They represent glacioeustatic sea-level falls during the long-term late Aptian-early Albian lowstand. The positive δ13C signature of Pietraroja Lagerstätten was determined by global rather than local paleoenvironmental and paleoecological processes, regardless of their contrasting background hydroclimatic conditions and the tendency of paralic waters for lighter δ13C values. This study demonstrates that peritidal-paralic limestones can reliably record global climatic-environmental and chemostratigraphic signals, offering a robust basis for constraining carbonate platform exposure events and enabling supra-regional, millennial-scale paleoclimatic reconstructions with near-modern temporal resolution.