Chapter Seven Paleoceanographical Proxies Based on Deep-Sea Benthic Foraminiferal Assemblage Characteristics

Abstract

This chapter focuses on the paleoceanographical proxies based on deep-sea benthic foraminiferal assemblage characteristics, and presents the following three proxy relationships that are promising: those between benthic foraminiferal faunas and benthic ecosystem oxygenation, export productivity, and deep-sea water mass characteristics. Under most circumstances the composition of deep-sea benthic foraminiferal assemblages is controlled by a rather limited number of environmental factors. The available proxies based on benthic foraminiferal assemblage composition show that they have major potential, but further research is needed to add or improve the quantitative aspects. In many cases, such as bottom water oxygenation, and Corg flux to the ocean floor, it can be done by significantly increasing the size of existing databases. In other cases such as periodicity of the organic flux, time series observations are necessary. A major obstacle is insufficient knowledge of the differences between recent and fossil faunas due to taphonomical alterations. This phenomenon, of importance for all paleoceanographic proxies, can to some extent be solved relatively easily in the case of foraminiferal assemblages by detailed studies of their vertical succession in sediments deposited in the last 5,000 years, when environmental conditions were probably rather invariable in many areas. Proxies based on foraminiferal assemblage composition are fundamentally different from all geochemical proxies, and thus may provide independent reconstructions of essential oceanographic parameters.