Calcium isotopic composition of planktonic foraminifera from ODP Site 154-925 ...

• Main Authors: Sime, N G, De La Rocha, Christina L, Tipper, Edward T, Tripati, Aradhna K, Galy, Albert, Bickle, Michael J
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 2007
• Subjects: Composite Core; Leg154; Joides Resolution; Ocean Drilling Program ODP; Planktonic foraminifera
• Online Access: https://dx.doi.org/10.1594/pangaea.711216; https://doi.pangaea.de/10.1594/PANGAEA.711216

An 18 million year record of the Ca isotopic composition (d44/42Ca) of planktonic foraminiferans from ODP site 925, in the Atlantic, on the Ceara Rise, provides the opportunity for critical analysis of Ca isotope-based reconstructions of the Ca cycle. ?44/42Ca in this record averages +0.37+/-0.05 (1 sigma SD) and ranges from +0.21‰ to +0.52‰. The record is a good match to previously published Neogene Ca isotope records based on foraminiferans, but is not similar to the record based on bulk carbonates, which has values that are as much as 0.25‰ lower. Bulk carbonate and planktonic foraminiferans from core tops differ slightly in their d44/42Ca (i.e., by 0.06+/-0.06‰ (n = 5)), while the difference between bulk carbonate and foraminiferan values further back in time is markedly larger, leaving open the question of the cause of the difference. Modeling the global Ca cycle from downcore variations in d44/42Ca by assuming fixed values for the isotopic composition of weathering inputs (d44/42Ca_w) and for isotope ... : Supplement to: Sime, N G; De La Rocha, Christina L; Tipper, Edward T; Tripati, Aradhna K; Galy, Albert; Bickle, Michael J (2007): Interpreting the Ca isotope record of marine biogenic carbonates. Geochimica et Cosmochimica Acta, 71(16), 3979-3989 ...