Glacial to interglacial primary production and El Nino-Southern Oscillation dynamics inferred from coccolithophores of the Santa Barbara Basin

• Published in: Paleoceanography
• Main Authors: Grelaud, Michael, BEAUFORT, Luc, Cuven, Stéphanie, Buchet, Noëlle
• Other Authors: Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2009
• Subjects: [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Pacific; Dansgaard-Oeschger events
• Online Access: https://hal.archives-ouvertes.fr/hal-01458318; https://hal.archives-ouvertes.fr/hal-01458318/document; https://hal.archives-ouvertes.fr/hal-01458318/file/2007PA001578.pdf; https://doi.org/10.1029/2007PA001578

International audience We investigate the long-term stability of El Nino-Southern Oscillation and Pacific Decadal Oscillation based on the examination of coccolithophore assemblages in a largely laminated 35 ka sedimentary record, retrieved in the Santa Barbara Basin (core MD02-2503). At a centennial scale coccolith assemblages indicate low primary production in the basin from 35 to 11.5 ka B. P., whereas the Holocene is characterized by high-productivity conditions. This pattern demonstrates the influence of the glacial-interglacial cycles on productivity and, by inference, on the nutrient supply by the upwelling cell off Point of Conception. On a shorter scale, laminations associated with Dansgaard-Oeschger events appear to be due to an injection of poorly oxygenated waters in the deepest part of the basin rather than anoxia due to high primary production. A seasonal sampling in seven laminated sections (spanning from 20 to 220 years) extracted from Holocene, Bolling-Allerod, and Dansgaard-Oeschger event 3 indicates El Nino probably existed continuously during the last 28 ka. The frequency of El Nino varied through time (between 1/2.5 and 1/5 event a(-1)) and appearing to follow the precession cycle. El Nino exhibits higher (lower) frequencies when the precession values are lower (higher). Finally, the Holocene is characterized by a decrease in El Nino's frequencies due to the reinforcement of El Nino through this period.