Cretaceous Oceanic Red Beds (CORBs) are commonly interpreted as records of persistently oxic pelagic conditions, but whether their deposition requires a specific combination of climate, sediment supply, and circulation remains debated. Here, we compare two CORB intervals formed on the same structural high under different paleoenvironmental regimes: the upper Aptian Puez-Redbed Member (P3) and the upper Albian–lower Cenomanian Puez-Marl Member (P5) of the Puez Formation (Trento Plateau, NE Italy). We integrate major- and trace-element geochemistry, PAAS-normalized rare earth element (REE) patterns, redox-sensitive ratios, and thermomagnetic proxies to constrain ventilation and sediment supply. Both intervals indicate sustained oxygenation at the sediment–water interface, as shown by negative Ce anomalies, oxic Th/U and Ni/Co ratios, Fe-oxide–dominated magnetic assemblages, and pervasive bioturbation. However, they record distinct environmental states. P3 represents a relatively shallower, more dynamically ventilated setting with variable weathering intensity and fluctuating carbonate versus detrital input, whereas P5 reflects deeper, more distal, and clay-rich deposition under more stable conditions. REE patterns support this distinction, with higher ΣREE and convex MREE–HREE enrichment in P3, versus lower ΣREE and flatter spectra in P5, consistent with reduced net scavenging/retention efficiency and stronger terrigenous dilution in the upper Albian–lower Cenomanian interval. These results show that sustained sediment–water interface oxygenation can be maintained across different local sedimentological regimes, indicating that CORB development does not require a single climate–sediment template and supporting their use as archives of mid-Cretaceous water-mass ventilation. • Multiproxy geochemistry and rock magnetism compare upper Aptian and Albian–Cenomanian CORBs at Puez. • Both intervals record sustained bottom-water oxygenation (Ce anomaly, Th/U, Ni/Co, Fe-oxide magnetic assemblages). • Upper Aptian CORBs reflects shallower, dynamically ventilated conditions with variable weathering and carbonate productivity. • Albian-Cenomanian reflects deeper, distal and clay-rich deposition under stable, nutrient-limited conditions. • PAAS-normalized REE patterns fingerprint scavenging efficiency and paleodepth, refining CORB formation models.
Leone et al. (Wed,) studied this question.