Figure 1. Locations of Atlantic and Vocontian Basin oceanic anoxic event (OAE) 1b sites superimposed on the paleogeographic map of the mid-Cretaceous, ca. 110 Ma (from Wagner et al., 2007). A: Biostratigraphy, lithology, and sedimentary structures across studied section (389.5–391.0 m below seafloor), including the OAE 1b black shale unit at Deep Sea Drilling Project (DSDP; ODP—Ocean Drilling Program) Site 545 (Shipboard Scientific Party, 1984). Core photo shows gradational contact at base of the black shale. B: Bulk carbonate stable carbon isotopic (¹³ C_carb) records (vs. Peedee belemnite, PDB) covering OAE 1b (light gray shading) at three different locations.