Long-term, high-resolution foraminiferal geochemical records (δ¹⁸O, δ¹³C) from IODP Site 359-U1467

DOI

Due to their large heat and moisture storage capabilities, the tropics are fundamental in modulating both regional and global climate. Furthermore, their thermal response during past extreme warming periods, such as super interglacials, is not fully resolved. In this regard, we present high-resolution (analytical) foraminiferal geochemical (δ^18^O and Mg/Ca) records for the last 1800 kyr from the shallow (487 m) Inner Sea drift deposits of the Maldives archipelago in the equatorial Indian Ocean. Considering the diagenetic susceptibility of these proxies, in carbonate-rich environments, we assess the integrity of a suite of commonly used planktonic and benthic foraminifera geochemical datasets (Globigerinoides ruber (white), Globigerinita glutinata (with bulla), Pulleniatina obliquiloculata (with cortex) and Cibicides mabahethi) and their use for future paleoceanographic reconstructions.Using a combination of spot Secondary Ion Mass Spectrometer, Electron Probe Micro-Analyzer and Scanning Electron Microscope image data, it is evident that authigenic overgrowths are present on both the external and internal test (shell) surfaces, yet the degree down-core as well as the associated bias is shown to be variable across the investigated species and proxies. Given the elevated authigenic overgrowth Mg/Ca (∼12–22 mmol/mol) and δ^18^O values (closer to the benthic isotopic compositions) the whole-test planktonic G. ruber (w) geochemical records are notably impacted beyond ∼627.4 ka (24.7 mcd). Yet, considering the setting (i.e. bottom water location) for overgrowth formation, the benthic foraminifera δ^18^O record is markedly less impacted with only minor diagenetic bias beyond ∼790.0 ka (28.7 mcd). Even though only the top of the G. ruber (w) and C. mabahethi records (whole-test data) would be suitable for paleo-reconstructions of absolute values (i.e. sea surface temperature, salinity, seawater δ^18^O), the long-term cycles, while dampened, appear to be preserved. Furthermore, planktonic species with thicker-tests (i.e. P. obliquiloculata (w/c)) might be better suited, in comparison to thinner-test counter-parts (i.e. G. glutinata (w/b), G. ruber (w)), for traditional whole-test geochemical studies in shallow, carbonate-rich environments. A thicker test equates to a smaller overall bias from the authigenic overgrowth. Overall, if the diagenetic impact is constrained, as done in this study, these types of diagenetically altered geochemical records can still significantly contribute to studies relating to past tropical seawater temperatures, latitudinal scale ocean current shifts and South Asian Monsoon dynamics.

Version 2, 2022-01-10: Previous version doi:10.1594/PANGAEA.914883.The new version includes updated Core 359-U1467C-1H-2 sample labels.

Identifier
DOI https://doi.org/10.1594/PANGAEA.939911
Related Identifier https://doi.org/10.1016/j.epsl.2020.116390
Related Identifier https://doi.org/10.1594/PANGAEA.914882
Related Identifier https://doi.org/10.1007/s00015-018-0304-9
Related Identifier https://doi.org/10.1594/PANGAEA.914883
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.939911
Provenance
Creator Stainbank, Stephanie ORCID logo; Spezzaferri, Silvia; De Boever, Eva ORCID logo; Bouvier, Anne-Sophie (ORCID: 0000-0002-5202-603X); Chilcott, Colin; de Leau, Erica S; Foubert, Anneleen ORCID logo; Kunkelova, Tereza; Pichevin, Laetitia ORCID logo; Raddatz, Jacek ORCID logo; Rüggeberg, Andres ORCID logo; Wright, James D ORCID logo; Yu, Siyao M; Zhang, Manlin; Kroon, Dick
Publisher PANGAEA
Publication Year 2022
Rights Creative Commons Attribution 4.0 International; https://creativecommons.org/licenses/by/4.0/
OpenAccess true
Representation
Resource Type Dataset
Format text/tab-separated-values
Size 11221 data points
Discipline Earth System Research
Spatial Coverage (73.284W, 4.850S, 73.284E, 4.851N)
Temporal Coverage Begin 2015-10-29T04:00:00Z
Temporal Coverage End 2015-11-03T19:10:00Z