A core-top study of dissolution effect on B/Ca in Globigerinoides sacculifer from the tropical Atlantic: Potential bias for paleo-reconstruction of seawater carbonate chemistry - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Geochemistry, Geophysics, Geosystems Année : 2013

A core-top study of dissolution effect on B/Ca in Globigerinoides sacculifer from the tropical Atlantic: Potential bias for paleo-reconstruction of seawater carbonate chemistry

Résumé

has been recently shown that B/Ca in planktonic foraminiferal calcite can be used as a proxy for seawater pH. Based on the study of surface sediments (multi-cores) retrieved along a depth transect on the Sierra Leone Rise (Eastern Equatorial Atlantic), we document the decrease of B/Ca and Mg/Ca of Globigerinoides sacculifer shells with increasing water depth and dissolution. This effect of dissolution on B/Ca may potentially represent a severe bias for paleo-pH reconstructions using this species. Samples of G. sacculifer were analyzed independently at two laboratories for B/Ca and Mg/Ca. Both sets of results show a systematic decrease of B/Ca and Mg/Ca along the depth transect, with an overall loss of ~14 µmol/mol (~15%) for B/Ca and of ~0.7 mmol/mol (~21%) for Mg/Ca between the shallowest (2640 m) and the deepest (4950 m) sites. Because of this dissolution effect, surface water pH reconstructed from B/Ca of G. sacculifer decreases by ~0.11 units between the shallowest site and the deepest site, a magnitude similar to the expected glacial/interglacial surface water pH changes.
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hal-00873400 , version 1 (09-10-2020)

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R. Coadic, Franck Bassinot, Elisabeth Michel, Mervyn Greaves, Delphine Dissard, et al.. A core-top study of dissolution effect on B/Ca in Globigerinoides sacculifer from the tropical Atlantic: Potential bias for paleo-reconstruction of seawater carbonate chemistry. Geochemistry, Geophysics, Geosystems, 2013, 14 (4), pp.1053-1068. ⟨10.1029/2012GC004296⟩. ⟨hal-00873400⟩
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