Laser ablation ICP-MS in paleoceanography: A regional study on the benthic foraminifer Oridorsalis umbonatus in the Benguela Upwelling Area off Namibia

Abstract

Benthic foraminiferal species colonize wide areas of the ocean floor and are widely used in paleoceanography. In paleoceanography it is important to continuously develop and refine proxies. The main focus of this thesis is a regional examination of the trace element ratios of O. umbonatus and test their suitability in paleoceanographic applications. Trace elements were measured using LA-ICP-MS on core top samples collected along a transect off Namibia and Mg/Ca ratios where than calibrated against BWTs. The influence of the carbonate ion concentration of sea water and pore-water on trace element and stable isotope incorporation in tests has been discussed and the implications on O. umbonatus was analyzed. These findings were used to investigate the changes in the water mass stratification between the Holocene and the LGM. The sea water density of our samples reveals that our samples follow the regular water mass sequence. BWTs show nearly no changes between the LGM and the Holocene.