Geochemistry of tropical Atlantic sediments of Marine Isotope Stage 4 ...

• Published in: Life
• Main Authors: Griffiths, James D, Barker, Stephen, Hendry, Katharine R, Thornalley, David J R, van de Flierdt, Tina, Hall, Ian R, Anderson, Robert F
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 2013
• Subjects: Antarc*; Antarctic; Southern Ocean
• Online Access: https://dx.doi.org/10.1594/pangaea.822026; https://doi.pangaea.de/10.1594/PANGAEA.822026

Antarctic Intermediate Water (AAIW) and Subantarctic Mode Water (SAMW) are the main conduits for the supply of dissolved silicon (silicic acid) from the deep Southern Ocean (SO) to the low-latitude surface ocean and therefore have an important control on low-latitude diatom productivity. Enhanced supply of silicic acid by AAIW (and SAMW) during glacial periods may have enabled tropical diatoms to outcompete carbonate-producing phytoplankton, decreasing the relative export of inorganic to organic carbon to the deep ocean and lowering atmospheric pCO2. This mechanism is known as the "silicic acid leakage hypothesis" (SALH). Here we present records of neodymium and silicon isotopes from the western tropical Atlantic that provide the first direct evidence of increased silicic acid leakage from the Southern Ocean to the tropical Atlantic within AAIW during glacial Marine Isotope Stage 4 (~60-70 ka). This leakage was approximately coeval with enhanced diatom export in the NW Atlantic and across the eastern ... : Supplement to: Griffiths, James D; Barker, Stephen; Hendry, Katharine R; Thornalley, David J R; van de Flierdt, Tina; Hall, Ian R; Anderson, Robert F (2013): Evidence of silicic acid leakage to the tropical Atlantic via Antarctic Intermediate Water during Marine Isotope Stage 4. Paleoceanography, 28(2), 307-318 ...