Organic carbon and total sulfur content and concentrations of selected molecular fossils for C/T black shales (Table 1)

• Main Authors: Sinninghe Damsté, Jaap S, Köster, Jürgen
• Format: Dataset
• Language: English
• Published: PANGAEA 1998
• Subjects: 103-641A; 11-105; 14-144; 41-367; 41-368; 51-417D; 80-551; 93-603B; Area/locality; Carbon; organic; total; Concentration of molecular fossils; Deep Sea Drilling Project; DEPTH; sediment/rock; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Element analyser CS; LECO; Elevation of event; Event label; Gas chromatography - Mass spectrometry (GC-MS); Glomar Challenger; Hopane isomerization; Joides Resolution; Latitude of event; Leg103; Leg11; Leg14; Leg41; Leg51; Leg80; Leg93; Longitude of event; North Atlantic/BASIN; North Atlantic/CONT RISE; North Atlantic/ESCARPMENT; North Atlantic/HILL; North Atlantic Ocean; Ocean Drilling Program; ODP; Paleoelevation; Sample code/label; Sulfur; North Atlantic
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.721057; https://doi.org/10.1594/PANGAEA.721057

During mid-Cretaceous times large amounts of organic carbon (Corg) became sequestered in 'black shales', possibly due to 'oceanic anoxic events' characterized by the development of an extended oxygen minimum zone (OMZ). Here, we provide the first direct evidence for an open ocean OMZ in the Cenomanian/Turonian (C/T) southern North Atlantic and in fact show that the base of the photic zone was euxinic as revealed by molecular fossils from photosynthetic green sulfur bacteria in C/T black shales. This, together with evidence for bottom water anoxia and accumulation of redox-sensitive trace metals and hydrogen-rich organic matter, indicates a continuously euxinic water column. Concurrent with the high Corg accumulation rates, which are 15-150 times greater in the southern than in the northern North Atlantic, and the low biological productivity, this suggests that preservation controlled the accumulation of Corg in C/T black shales.