Ocean and climate
Coccolith carbonate in ocean history
Coccoliths build up the dominant part of the total carbonate in the Pleistocene as shown for Site 1082 off SW-Africa where they constitute a significant fraction of the carbonate content during most of the last 680ka.Only few species significantly contribute to the coccolith carbonate. The relatively massive species C. leptoporus and C. pelagicus as well as the numerically dominant gephyrocapsids are the most important contributors. The calculated coccolith carbonate content is obviously linked to the bulk carbonate record and, therefore, is indicative for the development of the productivity regime of this area. The dominance of coccolith carbonate of up to >80 wt-% (>95% of the total carbonate) during the mid-Brunhes time (580 to 280 ka) indicate that a change in the productivity of the northern Benguela upwelling system have occurred. This time interval is characterised by a significant increase in carbonate (total as well as in coccolith derived CaCO3) that is associated with the appearance of Gephyrocapsa caribbeanica.

Baumann, K.-H. & Freitag, T. (2004): Pleistocene fluctuations in the Benguela Current system as revealed by coccolith assemblages. Marine Micropaleontology, 52: 195-215.
Preiss-Daimler, I., Baumann, K.-H. & Henrich, R. (2012): Carbonate budget mass estimates for Neogene discoasters from the Equatorial Atlantic (Ceara Rise: ODP Site 927). Micropaleontology, 31(2):169-178. DOI: 10.1144/0262-821X11-014.

Coccolith carbonate data Site 1082 (Baumann & Freitag, 2004)

Carbonate preservation
The physical and chemical properties of the intermediate and deep-water masses are analyzed by default today on investigations of the stable oxygen and carbon isotope ratios, nutrients and various radionuclides'. This is in addition to research done since the 1960 in pioneering studies, which used the preservation of carbonate particles to reconstruct water mass corrosiveness of ocean currents.Here, a very wide range of methods and proxies with very different resolutions and accuracy were used. In several studies, focusing on improving calibration methodology, members of the Working Group compared the entire range of conventional comparative methods, tested these in relationship to its potential applications and highlighting its limitation (Dittert et al. 1999, Henrich et al. 2003). It was also actively worked on the development of new proxies indicative of carbonate preservation, in particular, conservation indices on individual planktonic foraminifera using SEM data (BDX-Volberg and Henrich 2002, NDX-Henrich 1989). Similarly, pteropods (LDX-Gerhardt and Henrich 2001) and various parameters of the carbonate silt (Gröger et al 2003) were successfully used in various paleoceanographic case studies within the Atlantic Ocean (see publications).

Carbonate fluxes
The fluxes of the major groups of calcareous plankton in the surface waters in large areas of the world ocean are still poorly understood and thus quantified. This is particularly true with respect to quantitative data on the production and accumulation of various calcareous organisms.

Within the group "Sedimentology / Paleoceanography", new innovative methodology were developed for approaching these novel and highly current questions. The new methodologies include first full quantitative analysis of the entire Coccolith carbonate and individual Coccolith specimen (Baumann et al. 2005), using a range of SEM measurement parameters, and the full quantitative assessment of planktonic foraminifera, pteropods and coccoliths using bulk carbonate content and the silt grain size data (Baumann et al. 2003, Frenz et al. 2005). This was the first time, paleo-fluxes of the above-mentioned groups has been done for individual time slices (recent and in the Quaternary period) and longer-term records (Miocene - Recent) at oceanographic key positions in the Atlantic. Additionally, these records could be used for paleoceanographic interpretations.






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University of Bremen Research Group Sedimentology – Palaeoceanography
Faculty of Geosciences | FB5