HR: 14:40h
AN: OS22C-05    [PDF]
TI: A 35,000 years record of the Oceanic Primary production variability in the Santa Barbara basin
AU: * Beaufort, L
EM: beaufort@cerege.fr
AF: CNRS CEREGE, Europole de l'Arbois BP 80, Aix-en-Provence, 13545 C04 France
AU: Cuven, S
EM: phanie.cuven@infonie.fr
AF: CNRS CEREGE, Europole de l'Arbois BP 80, Aix-en-Provence, 13545 C04 France
AU: Buchet, N
EM: nbuchet@cerege.fr
AF: CNRS CEREGE, Europole de l'Arbois BP 80, Aix-en-Provence, 13545 C04 France
AB: The high sedimentation rate of the Santa Barbara Basin has attracted many paleoclimatic studies since drilling of ODP Site 893. In particular the occurrence of laminated sediments during each Dansgaard-Oeschger (D/O) event is particularly intriguing. The reason of these anoxic events can be related either to higher primary production or to change in the chemistry of the intermediate water that fill the deep part of the basin. Here we present a record of primary production (PP) estimations based on coccolith assemblages. It is based on the relative abundance of deep photic zone flora (Florisphaera profunda) versus the upper photic zone flora. This record has been established on Core MD02-2103 in the vicinity of ODP Site 893 during the IMAGES-VIII cruise (2003). The PP record shows higher PP during the Holocene and Boelling Allerod (250 g C/m2/year) than during the Youger Dryas, MIS 2 and MIS 3 (150 g C/m2/year). This record therefore confirms the importance of Glacial/Interglacial influence on strength and path of the California current. During the D/O events no significant increase of primary production is observed, implying that the preservation of laminations during these events is controlled more by the chemistry of the intermediate water rather than by primary production. In order to check the variability of El Nino Southern Oscillation through time and how ENSO influence PP in that contest, we sampled lamina in some intervals (Holocene, Boelling Allerod and D/0 5). Preliminary analysis of a 20 years record from the upper Holocene indicates that the ratio between two Emiliania huxleyi morphotypes show small but significant seasonal variability and a 5-6 year period which may correspond to ENSO cycle.
DE: 4267 Paleoceanography
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting