Calibration of Na partitioning in the calcitic foraminifer Operculina ammonoides under variable Ca concentration: Toward reconstructing past seawater composition

Hauzer, Hagar; Evans, David; Müller, Wolfgang; Rosenthal, Yair; Erez, Jonathan

doi:10.1016/j.epsl.2018.06.004

Cited by 43 publications

(56 citation statements)

References 51 publications

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“…Shading encloses the 95% CI of an ensemble of Gaussian smoothed fits to the data, used in the seawater‐enabled BAYMAG models. (b) Relationship between observed Mg/Ca s w and linear predictions of Mg/Ca s w from Mg/Ca of calcite in laboratory inorganic precipitation (Mucci & Morse, ) and foraminiferal culture studies (De Nooijer et al, ; Delaney et al, ; Evans et al, ; Evans, Brierley, et al, ; Hauzer et al, ; Mewes et al, ; Raitzsch et al, ; Segev & Erez, ).…”

Section: Use Of Baymag On Longer Geological Timescalesmentioning

confidence: 99%

“…Previous work has suggested that the incorporation of Mg into calcite varies nonlinearly with Mg/Ca sw , necessitating a power function correction (Evans & Müller, 2012), rather than a simple ratio between the past value and the modern value as we suggest above. To re-examine whether such an adjustment is necessary, we compiled experimental data in which planktic and benthic foraminifera were cultured at varying Mg/Ca sw concentrations (De Nooijer et al, 2017;Delaney et al, 1985;Evans et al, 2015;Evans, Brierley, et al, 2016;Hauzer et al, 2018;Mewes et al, 2014;Raitzsch et al, 2010;Segev & Erez, 2006), along with an inorganic precipitation experiment (Mucci & Morse, 1983) (Figure 9b). These data span values of Mg/Ca sw from 0.5 to 10 mmol/mol (Figure 9b), which encompasses the range found throughout the Phanerozoic (0.5-6 mmol/mol, Dickson, 2002;Dickson, 2004).…”

Section: Incorporating Changes In Mg/ca Of Seawatermentioning

confidence: 99%

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Bayesian Calibration of the Mg/Ca Paleothermometer in Planktic Foraminifera

Tierney

Malevich

Gray

et al. 2019

Paleoceanog and Paleoclimatol

146

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The Mg/Ca ratio of planktic foraminifera is a widely used proxy for sea-surface temperature but is also sensitive to other environmental factors. Previous work has relied on correcting Mg/Ca for nonthermal influences. Here, we develop a set of Bayesian models for Mg/Ca in four major planktic groups-Globigerinoides ruber (including both pink and white chromotypes), Trilobatus sacculifer, Globigerina bulloides, and Neogloboquadrina pachyderma (including N. incompta)-that account for the multivariate influences on this proxy in an integrated framework. We use a hierarchical model design that leverages information from both laboratory culture studies and globally distributed core top data, allowing us to include environmental sensitivities that are poorly constrained by core top observations alone. For applications over longer geological timescales, we develop a version of the model that incorporates changes in the Mg/Ca ratio of seawater. We test our models-collectively referred to as BAYMAG-on sediment trap data and on representative paleoclimate time series and demonstrate good agreement with observations and independent sea-surface temperature proxies. BAYMAG provides probabilistic estimates of past temperatures that can accommodate uncertainties in other environmental influences, enhancing our ability to interpret signals encoded in Mg/Ca. Plain Language SummaryThe amount of magnesium (Mg) incorporated into the calcite shells of tiny protists called foraminifera is determined by the temperature of the water in which they grew. This allows paleoclimatologists to measure the magnesium-to-calcium (Mg/Ca) ratio of fossil foraminiferal shells and determine how past sea-surface temperatures have changed. However, other factors can influence Mg/Ca, like the salinity and pH of seawater. Here, we develop Bayesian models of foraminiferal Mg/Ca that account for all of the influences on Mg/Ca and show how we can use these to improve our interpretations of Mg/Ca data. Culture experiments provide precise constraints on environmental sensitivities but are limited in that laboratory conditions are not perfect analogs for the natural environment. Sediment traps have an advantage in that seasonality of foraminiferal occurrence and corresponding ocean temperatures are well constrained, but they do not account for the effects of dissolution or bioturbation. Sedimentary core tops integrate effects associated with both occurrence and preservation and are thus better analogs for the conditions typical of the geological record, but uncertainties in seasonal preferences and the depth of calcification can in some cases lead to misleading inference of secondary environmental sensitivities (Hertzberg & Schmidt, 2013;Hönisch et al., 2013).Here, we use both core top and laboratory culture data to develop a suite of Bayesian hierarchical models for Mg/Ca. We collate over 1,000 sedimentary Mg/Ca measurements to formulate new calibrations for four major planktic groups: Globigerinoides ruber (including both pink and white chromotypes), Trilobat...

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Section: Use Of Baymag On Longer Geological Timescalesmentioning

confidence: 99%

Section: Incorporating Changes In Mg/ca Of Seawatermentioning

confidence: 99%

Bayesian Calibration of the Mg/Ca Paleothermometer in Planktic Foraminifera

Tierney

Malevich

Gray

et al. 2019

Paleoceanog and Paleoclimatol

146

View full text Add to dashboard Cite

show abstract

“…Foraminiferal shell, spine (base) and organic linings differ in Na composition, potentially due to leakage (Yoshimura et al, 2017), banding (Branson et al, 2016;Geerken et al, 2018), diffusion or adhesion and may vary as a function of salinity (Allen et al, 2016;Geerken et al, 2018;Mezger et al 2016Mezger et al , 2018Wit et al, 2013) or calcium concentration of the seawater (Hauzer et al, 2018) (Fig. 7).…”

Section: Unraveling Spines and Spine Base Na/camentioning

confidence: 99%

Planktonic foraminiferal spine versus shell carbonate Na incorporation in relation to salinity

et al. 2019

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Abstract. Sea surface salinity is one of the most important parameters to reconstruct in paleoclimatology, reflecting amongst other things the hydrological cycle, paleodensity, ice volume, and regional and global circulation of water masses. Recent culture studies and a Red Sea field study revealed a significant positive relation between salinity and Na incorporation within benthic and planktonic foraminiferal shells. However, these studies reported varying partitioning of Na between and within the same species. The latter could be associated with ontogenetic variations, most likely spine loss. Varying Na concentrations were observed in different parts of foraminiferal shells, with spines and regions close to the primary organic sheet being especially enriched in Na. In this study, we unravel the Na composition of different components of the planktonic foraminiferal shell wall using electron probe micro-analysis (EPMA) and solution ICP-MS. A model is presented to interpret EPMA data for spines and spine bases to quantitatively assess differences in composition and contribution to whole-shell Na∕Ca signals. The same model can also be applied to other spatial inhomogeneities observed in foraminiferal shell chemistry, like elemental (e.g., Mg, Na, S) banding and/or hotspots. The relative contribution of shell carbonate, organic linings, spines and spine bases to whole-shell Na chemistry is considered quantitatively. This study shows that whereas the high Na areas may be susceptible to taphonomic alterations, the Na chemistry of the shell itself seems relatively robust. Comparing both shell and spine Na∕Ca values with salinity shows that shell chemistry records salinity, albeit with a very modest slope.

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“…b. Relationship between observed Mg/Casw and linear predictions of Mg/Casw from Mg/Ca of calcite in laboratory inorganic precipitation (Mucci & Morse, 1983) and foraminiferal culture studies (Delaney et al, 1985;Segev & Erez, 2006;Raitzsch et al, 2010;Mewes et al, 2014;Evans et al, 2015;Evans, Brierley, et al, 2016;De Nooijer et al, 2017;Hauzer et al, 2018).…”

Section: Inversion Of Baymag To Predict Past Sstmentioning

confidence: 99%

“…Previous work has suggested that the incorporation of Mg into calcite varies nonlinearly with Mg/Ca sw , necessitating a power function correction (Evans & Müller, 2012), rather than a simple ratio between the past value and the modern value as we suggest above. To re-examine whether such an adjustment is necessary, we compiled experimental data in which planktic and benthic foraminifera were cultured at varying Mg/Ca sw concentrations (Delaney et al, 1985;Segev & Erez, 2006;Raitzsch et al, 2010;Mewes et al, 2014;Evans et al, 2015;Evans, Brierley, et al, 2016;De Nooijer et al, 2017;Hauzer et al, 2018), along with an inorganic precipitation experiment (Mucci & Morse, 1983) ( Fig. 9b).…”

Section: Inversion Of Baymag To Predict Past Sstmentioning

confidence: 99%

Bayesian calibration of the Mg/Ca paleothermometer in planktic foraminifera

Tierney¹,

Malevich²,

Gray³

et al. 2019

Preprint

View full text Add to dashboard Cite

The Mg/Ca ratio of planktic foraminifera is a widely used proxy for sea‐surface temperature but is also sensitive to other environmental factors. Previous work has relied on correcting Mg/Ca for nonthermal influences. Here, we develop a set of Bayesian models for Mg/Ca in four major planktic groups—Globigerinoides ruber (including both pink and white chromotypes), Trilobatus sacculifer, Globigerina bulloides, and Neogloboquadrina pachyderma (including N. incompta)—that account for the multivariate influences on this proxy in an integrated framework. We use a hierarchical model design that leverages information from both laboratory culture studies and globally distributed core top data, allowing us to include environmental sensitivities that are poorly constrained by core top observations alone. For applications over longer geological timescales, we develop a version of the model that incorporates changes in the Mg/Ca ratio of seawater. We test our models—collectively referred to as BAYMAG—on sediment trap data and on representative paleoclimate time series and demonstrate good agreement with observations and independent sea‐surface temperature proxies. BAYMAG provides probabilistic estimates of past temperatures that can accommodate uncertainties in other environmental influences, enhancing our ability to interpret signals encoded in Mg/Ca.

show abstract

Calibration of Na partitioning in the calcitic foraminifer Operculina ammonoides under variable Ca concentration: Toward reconstructing past seawater composition

Cited by 43 publications

References 51 publications

Bayesian Calibration of the Mg/Ca Paleothermometer in Planktic Foraminifera

Bayesian Calibration of the Mg/Ca Paleothermometer in Planktic Foraminifera

Planktonic foraminiferal spine versus shell carbonate Na incorporation in relation to salinity

Bayesian calibration of the Mg/Ca paleothermometer in planktic foraminifera

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