Valve concentration of Ethmodiscus sp. and carbon in sediment core GeoB3801-6, supplement to: Romero, Oscar E; Schmieder, Frank (2006): Occurrence of thick Ethmodiscus oozes associated with a terminal Mid-Pleistocene Transition event in the oligotrophic subtropical South Atlantic. Palaeogeography, Palaeoclimatology, Palaeoecology, 235(4), 321-329

• Main Author: Romero, Oscar E
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2006
• Subjects: DEPTH, sediment/rock; Diatoms, total abundance per unit sediment mass; Calcium carbonate; Carbon, organic, total; Gravity corer Kiel type; Counting, diatoms; Calculated, CaCO3=TC-TOC*8.333; Element analyser CHN-O Rapid, Heraeus; M34/3; Meteor 1986; Center for Marine Environmental Sciences MARUM; Geosciences, University of Bremen GeoB; Mid-Atlantic Ridge; Romero; NADW
• Online Access: https://dx.doi.org/10.1594/pangaea.327024; https://doi.pangaea.de/10.1594/PANGAEA.327024

Within generally calcareous sediment sequences, layers of variable thickness of the giant diatom Ethmodiscus were found in five cores recovered in the Subtropical South Atlantic between 23° and 33°S from both sides of the Mid-Atlantic Ridge. Two types of oozes occur: (almost) monospecific layers of Ethmodiscus and layers dominated by Ethmodiscus, with several accompanying tropical/subtropical, oligotrophic-water diatoms. The two thickest Ethmodiscus layers occur in GeoB3801-6 around 29°S, and accumulated during late MIS 14 and MIS 12, respectively. Downcore concentrations of Ethmodiscus valves range between 3.4 10 4 and 2.3 10 7 valves g -1. We discuss the ooze formation in the context of migration of frontal systems and changes in the thermohaline circulation. The occurrence of Ethmodiscus oozes in sediments underlying the present-day pelagic, low-nutrient waters is associated with a terminal event of the Mid-Pleistocene Transition at around 530 ka, when the ocean circulation rearranged after a period of reduced NADW production.