Mg/Ca, B/Ca and U/Ca in shells of benthic foraminifers: Tracers of temperature and seawater carbonate chemistry

Abstract

Mg/Ca ratios in benthic foraminiferal shells are frequently used in paleoceanographic studies to estimate past bottom water temperatures. Apart from temperature, other factors may exert additional influences on foraminiferal Mg/Ca. These include the Mg/Ca ratio of seawater, partial dissolution of shell calcite, salinity, physiological effects, and, probably of capital importance, the carbonate chemistry of seawater. In this context, the separate effects of temperature and seawater carbonate chemistry on the magnesium incorporation into benthic foraminiferal calcite are unraveled and quantified in this thesis. Further, B/Ca and U/Ca in benthic foraminifers were investigated as potential carbonate system proxies that may be used to correct for the carbonate ion effect on Mg/Ca.