(Table 1, 2) Foraminifera biometric data, and boron isotopic composition of Globigerinoides sacculifer of sediments from the Ontong-Java Plateau

DOI

Sediment samples from the Ontong-Java Plateau in the Pacific and the 90° east ridge in the Indian Ocean were used to investigate whether shell size and early diagenesis affect d11B of the symbiont-bearing planktonic foraminifer Globigerinoides sacculifer. In pristine shells from both study locations we found a systematic increase of d11B and Mg/Ca with shell size. Shells in the sieve size class 515–865 µm revealed d11B values +2.1 to +2.3 per mil higher than shells in the 250–380 µm class. This pattern is most likely due to differences in symbiont photosynthetic activity and its integrated effect on the pH of the foraminiferal microenvironment. We therefore suggest smaller individuals must live at approximately 50–100 m water depth where ambient light levels are lower. Using the empirical calibration curve for d11B in G. sacculifer, only shells larger than 425 µm reflect surface seawater pH. Partial dissolution of shells derived from deeper sediment cores was determined by shell weight analyses and investigation of the shell surface microstructure by scanning electron microscopy. The d11B in partially dissolved shells is up to 2 per mil lower relative to pristine shells of the same size class. In agreement with a relatively higher weight loss in smaller shells, samples from the Ontong-Java Plateau show a more pronounced dissolution effect than larger shells. On the basis of the primary size effect and potential postdepositional dissolution effects, we recommend the use of shells that are visually pristine and, in the case of G. sacculifer, larger than 500 μm for paleoreconstructions.

Supplement to: Hönisch, Bärbel; Hemming, N Gary (2004): Ground-truthing the boron isotope-paleo-pH proxy in planktonic foraminifera shells: Partial dissolution and shell size effects. Paleoceanography, 19(4), PA4010

Identifier
DOI https://doi.org/10.1594/PANGAEA.837805
Related Identifier https://doi.org/10.1029/2004PA001026
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.837805
Provenance
Creator Hönisch, Bärbel; Hemming, N Gary
Publisher PANGAEA
Publication Year 2004
Rights Creative Commons Attribution 3.0 Unported; https://creativecommons.org/licenses/by/3.0/
OpenAccess true
Representation
Language English
Resource Type Supplementary Dataset; Dataset
Format text/tab-separated-values
Size 169 data points
Discipline Earth System Research
Spatial Coverage (88.350W, -6.350S, 168.870E, 3.747N)
Temporal Coverage Begin 1966-05-04T00:00:00Z
Temporal Coverage End 1977-07-23T00:00:00Z