HR: 0800h
AN: PP41B-0553    [Abstracts]
TI: Coccolithophore Record During the Middle Pleistocene in the North and South Atlantic: Productivity and Dissolution Patterns
AU: * Amore, F
EM: f.amore@unisannio.it
AF: Universit\` del Sannio Facoltà di Scienze Dipartimento Studi Geologici ed Ambientali, Via dei Mulini 59A, Benevento, BN 82100, Italy
AU: Flores, J
EM: flores@usal.es
AF: Universidad de Salamanca Facultad de Ciencias, Departamento de Geologia, Salamanca, 37008, Spain
AU: Filippelli, G
EM: gfilippe@iupui.edu
AF: Indiana University, Purdue University(IUPUI), Indianapolis, 46202, United States
AU: Volker, A
EM: avoelker@pro.softhome.net
AF: INETI, Departamento de Geologia Marinha, Lisbon, 1049-001, Portugal
AU: Sierro, F
EM: sierro@usal.es
AF: Universidad de Salamanca Facultad de Ciencias, Departamento de Geologia, Salamanca, 37008, Spain
AB: The coccolithophore assemblages of ODP Site 1089 (Cape Basin, Atlantic Ocean) and of piston core MD03- 2699, located in the Estremadura promontory (NW of Lisbon), were analyzed. The studied interval ranges from MIS 9 to MIS 13 and includes Mid-Brunhes event (MIS 9 to 11), which is considered one of the warmest during the Pleistocene. This interval is also characterized by generally high carbonate concentrations (and high productivity) with intervals of high dissolution in the deep ocean. The paradox of high carbonate production and high dissolution in certain intervals might be linked to nutrient available, ocean geochemistry, and upwelling. During MIS12 and 13 the assemblages are dominated by {\ it Gephyrocapsa caribbeanica} (a small but robust and well- calcified placolith). {\ it G. oceanica} shows low abundance values during MIS 11, 12 and 13. A light increase of the species is recorded, at ODP Site 1089, during MIS 10. We observed fluctuations in the degree of preservation in the calcareous nannofossil assemblages: interglacial periods are characterized of high to moderate dissolution, glacials by moderate to good calcareous nannofossil preservation. During Terminations IV and V we observed maxima in calcareous nannofossil accumulation, but with moderate preservation, indicating that maxima in calcareous nannofossil production occur during Terminations. The geochemical data from ODP site show that the P/Ti ratio, a paleoproductivity and P mass balance proxy, and Sr concentrations, a nannofossil production proxy, also show peaks during Terminations IV and V—thus, high production from nutrients coincides with high carbonate dissolution. In a coupled biological, chemical, and oceanographic model, low sea levels during glacials result in a basin dominance of the shelf-basin fractionation, with high nutrient delivery to the deep sea and increased carbonate production. Basin production then decreases with the increase of nutrient apportionment to the shelves during higher interglacial sea levels.
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4912 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4805)
DE: 4944 Micropaleontology (0459, 3030)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting