Calcium isotopes of planktonic foraminifera, supplement to: Heuser, Alexander; Eisenhauer, Anton; Böhm, Florian; Wallmann, Klaus; Gussone, Nikolaus; Pearson, Paul N; Nägler, Thomas F; Dullo, Wolf-Christian (2005): Calcium isotope (d44/40Ca) variations of Neogene planktonic foraminifera. Paleoceanography, 20(2), PA2013

Measurements of the calcium isotopic composition (d44/40Ca) of planktonic foraminifera from the western equatorial Pacific and the Indian sector of the Southern Ocean show variations of about 0.6 per mil over the past 24 Myr. The stacked d44/40Ca record of Globigerinoides trilobus and Globigerina bu...

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Bibliographic Details
Main Authors: Heuser, Alexander, Eisenhauer, Anton, Böhm, Florian, Wallmann, Klaus, Gussone, Nikolaus, Pearson, Paul N, Nägler, Thomas F, Dullo, Wolf-Christian
Format: Article in Journal/Newspaper
Language:English
Published: PANGAEA - Data Publisher for Earth & Environmental Science 2005
Subjects:
Ocean Drilling Program ODP
Southern Ocean
Pacific
Indian
Klaus
Planktonic foraminifera
Online Access:https://dx.doi.org/10.1594/pangaea.837160
https://doi.pangaea.de/10.1594/PANGAEA.837160
Description
Summary:Measurements of the calcium isotopic composition (d44/40Ca) of planktonic foraminifera from the western equatorial Pacific and the Indian sector of the Southern Ocean show variations of about 0.6 per mil over the past 24 Myr. The stacked d44/40Ca record of Globigerinoides trilobus and Globigerina bulloides indicates a minimum in d44/40Casw (seawater calcium) at 15 to 16 Ma and a subsequent general increase toward the present, interrupted by a second minimum at 3 to 5 Ma. Applying a coupled calcium/carbon cycle model, we find two scenarios that can explain a large portion of the observed d44/40Casw variations. In both cases, variations in the Ca input flux to the ocean without proportional changes in the carbonate flux are invoked. The first scenario increases the riverine calcium input to the ocean without a proportional increase of the carbonate flux. The second scenario generates an additional calcium flux from the exchange of Ca by Mg during dolomitization. In both cases the calcium flux variations lead to drastic changes in the seawater Ca concentrations on million year timescales. Our d44/40Casw record therefore indicates that the global calcium cycle may be much more dynamic than previously assumed.

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