Neodymium isotope ratios of fish debris from late Cretaceous black shales ...

• Main Authors: Jiménez Berrocosco, Álvaro, MacLeod, Kenneth G, Martin, Ellen E, Bourbon, Elodie, Isaza-Londoño, Carolina, Basak, Chandranath
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 2010
• Subjects: Ocean Drilling Program ODP; North Atlantic
• Online Access: https://dx.doi.org/10.1594/pangaea.792598; https://doi.pangaea.de/10.1594/PANGAEA.792598

Neodymium isotopes of fish debris from two sites on Demerara Rise, spanning ~4.5 m.y. of deposition from the early Cenomanian to just before ocean anoxic event 2 (OAE2) (Cenomanian-Turonian transition), suggest a circulation-controlled nutrient trap in intermediate waters of the western tropical North Atlantic that could explain continuous deposition of organic-rich black shales for as many as ~15 m.y. (Cenomanian-early Santonian). Unusually low Nd isotopic data (epsilon-Nd(t) ~-11 to ~-16) on Demerara Rise during the Cenomanian are confirmed, but the shallower site generally exhibits higher and more variable values. A scenario in which southwest-flowing Tethyan and/or North Atlantic waters overrode warm, saline Demerara bottom water explains the isotopic differences between sites and could create a dynamic nutrient trap controlled by circulation patterns in the absence of topographic barriers. Nutrient trapping, in turn, would explain the ~15 m.y. deposition of black shales through positive feedbacks ... : Supplement to: Jiménez Berrocosco, Álvaro; MacLeod, Kenneth G; Martin, Ellen E; Bourbon, Elodie; Isaza-Londoño, Carolina; Basak, Chandranath (2010): Nutrient trap for Late Cretaceous organic-rich black shales in the tropical North Atlantic. Geology, 38(12), 1111-1114 ...