Controls on Sr/Ca in benthic foraminifera and implications for seawater Sr/Ca during the late Pleistocene

Yu, Jimin, Elderfield, Henry, Jin, Zhangdong, Tomascak, Paul and Rohling, Eelco J. (2014) Controls on Sr/Ca in benthic foraminifera and implications for seawater Sr/Ca during the late Pleistocene. Quaternary Science Reviews, 98, 1-6. (doi:10.1016/j.quascirev.2014.05.018).

Abstract

Changes in the Sr to Ca ratio of sea water have important implications for the interpretation of past climate. It has proven difficult to interpret Sr/Ca of foraminiferal calcite as a measure of seawater Sr/Ca or as reflecting the influence of deep water carbonate ion saturation (Δ[CO₃^2-]) on the incorporation of Sr into benthic foraminiferal carbonate. Here, we address this issue by measurements of paired benthic foraminiferal Sr/Ca and B/Ca (a proxy for deep water Δ[CO₃^2-]) for core-tops from the global ocean and three down cores at different settings during the Last Glacial–interglacial cycle. These new data suggest a significant control of deep water Δ[CO₃^2-] on benthic foraminiferal Sr/Ca, and that down-core shell Sr/Ca variations can be largely accounted for by past deep water Δ[CO₃^2-] changes. We conclude that seawater Sr/Ca has likely remained near-constant on glacial–interglacial timescales during the late Pleistocene, in agreement with model results. With due caution, benthic Sr/Ca may be used as an auxiliary proxy for deep water Δ[CO₃^2-] if seawater Sr/Ca is constant.

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Contributors

Author: Eelco J. Rohling

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