Stable oxygen isotopes and Mg/Ca in planktic foraminifera from modern surface sediments of the Western Pacific Warm Pool : implications for thermocline reconstructions
Sanchez, Paola Moffa
Oppo, Delia W.
Martínez Méndez, Gema
MetadataShow full item record
KeywordWestern Pacific Warm Pool; Mg/Ca calibration; Oxygen isotopes; Planktic foraminifera; Thermocline reconstruction
Mg/Ca and stable oxygen isotope compositions (δ18O) of planktic foraminifera tests are commonly used as proxies to reconstruct past ocean conditions including variations in the vertical water column structure. Accurate proxy calibrations require thorough regional studies, since parameters such as calcification depth and temperature of planktic foraminifera depend on local environmental conditions. Here we present radiocarbon-dated, modern surface sediment samples and water column data (temperature, salinity, and seawater δ18O) from the Western Pacific Warm Pool. Seawater δ18O (δ18OSW) and salinity are used to calculate individual regressions for western Pacific surface and thermocline waters (δ18OSW = 0.37 × S-12.4 and δ18OSW = 0.33 × S-11.0). We combine shell δ18O and Mg/Ca with water column data to estimate calcification depths of several planktic foraminifera and establish regional Mg/Ca-temperature calibrations. Globigerinoides ruber, Globigerinoides elongatus, and Globigerinoides sacculifer reflect mixed layer conditions. Pulleniatina obliquiloculata and Neogloboquadrina dutertrei and Globorotalia tumida preserve upper and lower thermocline conditions, respectively. Our multispecies Mg/Ca-temperature calibration (Mg/Ca = 0.26exp0.097*T) matches published regressions. Assuming the same temperature sensitivity in all species, we propose species-specific calibrations that can be used to reconstruct upper water column temperatures. The Mg/Ca temperature dependencies of G. ruber, G. elongatus, and G. tumida are similar to published equations. However, our data imply that calcification temperatures of G. sacculifer, P. obliquiloculata, and N. dutertrei are exceptionally warm in the western tropical Pacific and thus underestimated by previously published calibrations. Regional Mg/Ca-temperature relations are best described by Mg/Ca = 0.24exp0.097*T for G. sacculifer and by Mg/Ca = 0.21exp0.097*T for P. obliquiloculata and N. dutertrei.
Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 32 (2017): 1174–1194, doi:10.1002/2017PA003122.
The publisher requires that this item be embargoed until 2018-05-09. Please check back after 2018-05-09.
Suggested CitationArticle: Hollstein, Martina, Mohtadi, Mahyar, Rosenthal, Yair, Sanchez, Paola Moffa, Oppo, Delia W., Martínez Méndez, Gema, Steinke, Stephan, Hebbeln, Dierk, "Stable oxygen isotopes and Mg/Ca in planktic foraminifera from modern surface sediments of the Western Pacific Warm Pool : implications for thermocline reconstructions", Paleoceanography 32 (2017): 1174–1194, DOI:10.1002/2017PA003122, https://hdl.handle.net/1912/9465
Showing items related by title, author, creator and subject.
Reconstructing the thermal structure of the upper ocean : insights from planktic foraminifera shell chemistry and alkenones in modern sediments of the tropical eastern Indian Ocean Mohtadi, Mahyar; Oppo, Delia W.; Luckge, Andreas; De Pol-Holz, Ricardo; Steinke, Stephan; Groeneveld, Jeroen; Hemme, Nils; Hebbeln, Dierk (American Geophysical Union, 2011-09-10)Shell chemistry of planktic foraminifera and the alkenone unsaturation index in 69 surface sediment samples in the tropical eastern Indian Ocean off West and South Indonesia were studied. Results were compared to modern ...
Last deglaciation in the Okinawa Trough : subtropical northwest Pacific link to Northern Hemisphere and tropical climate Sun, Youbin; Oppo, Delia W.; Xiang, Rong; Liu, Weiguo; Gao, Shu (American Geophysical Union, 2005-06-23)Detailed deglacial and Holocene records of planktonic δ18O and Mg/Ca–based sea surface temperature (SST) from the Okinawa Trough suggest that at ∼18 to 17 thousand years before present (kyr B.P.), late spring/early summer ...
Deciphering isotopic signals of monsoon-induced upwelling in foraminifera from the Western Arabian sea sediment trap Stuart, Dana R. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1997-03)Isotopic analyses have been made on four species of foraminifera collected with a PARFLUX Mark VI sediment trap in the Arabian Sea during the 1986 and 1987 monsoons. Two of the species are non-spinose thermocline dwellers ...