High‐Resolution C‐Isotope, TOC and Biostratigraphic Records of OAE 1a (Aptian) From an Expanded Hemipelagic Cored Succession, Western Tethys: A New Stratigraphic Reference for Global Correlation and Paleoenvironmental Reconstruction

A high-resolution carbonate C-isotope stratigraphy for the Aptian is presented Cau core (Spain). The biostratigraphically calibrated of used to refine previously defined segments Aptian. Thirteen have been identified and correlated, further subdivisions are presented. Correlation with other sections worldwide demonstrates robustness core. studied succession includes a continuous record early Oceanic Anoxic Event (OAE 1a). Its onset has at an ultrahigh-resolution scale (0.2–0.5 kyr spacing), revealing sharp δ13Ccarb negative spikes, interpreted as pulses volcanism methane emissions. largest spike was rapid (<10 kyr) marks base OAE 1a, which occurs within longer-term falling trend. profile across 1a perfectly records (C3/Ap3), positive (C4/Ap4), steady (C5/Ap5), (C6/Ap6) that were from Cismon (Italy) subsequently worldwide. Ap7 Ap14 excursion, coupled high TOC contents, probably related regional paleogeography. links global environmental changes, episodes widespread deposition organic matter, ultimately major volcanic discussed. We propose new reference section Aptian, specifically based on its expanded well-preserved sedimentary, geochemical biotic archives, provide insights into changes occurred during this time interval.