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Seminar Details

Why and how to measure the calcium concentration of past oceans?

Date

28/06/2018

Lecturers

Dr. Sandrine Lehouedec - The Hebrew University of Jerusalem; and The Interuniversity Institute for Marine Sciences in Eilat

Abstract

Throughout the history of the Earth the oceans were punctuated by periodical as well as extreme events that have changed in their chemistry. Such variations in the major ion concentrations of seawater are of prime interest because of their influence on the biomineralization of many marine organisms, especially calcifying ones. Up to now, the climatic reconstructions are based on the use of the paleothermometer Mg/Ca ratios of the foraminifera shells. However, on a million-year scale, the variation in seawater calcium concentration exerts a major control on the seawater Mg/Ca ratio and until today there is no direct proxy to reconstruct the calcium concentration of past seawater. Consequently the reconstructions of oceanic temperature are based on strong assumption about the Mg/Ca ratio of seawater leading to uncertainties about the reconstructed seawater temperatures. With this seminar I will explain why it became important for paleoclimatic studies to reconstruct the calcium concentration of ancient seawater and I will present how my current work at IUI, based on the cultures of foraminifera, can turn in help to solve this issue.

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