Chamber formation leads to Mg/Ca banding in the planktonic foraminifer Neogloboquadrina pachyderma

Jonkers, Lukas; Buse, Ben; Brummer, Geert-Jan A; Hall, Ian Robert

doi:10.1016/j.epsl.2016.07.030

Cited by 41 publications

(74 citation statements)

References 49 publications

(112 reference statements)

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“…The model of chamber formation and ontogenic day/night Mg-banding proposed above might also explain Mg-banding patterns observed in the planktic foraminifer Neogloquadrina pachyderma 36. Jonkers et al 36.…”

Section: Discussionmentioning

confidence: 91%

“…11c,d) and a low Mg/Ca ratio in the crust despite being deposited at constant temperature. Crust formation at constant calcification temperature has also been observed in cultured specimens of N. incompta (C. Davis, personal communication) and in sediment trap specimens of N. pachyderma 36. Clearly, the mechanisms responsible for crust formation and its Mg/Ca geochemistry remain to be resolved.…”

Section: Discussionmentioning

confidence: 94%

“…Jonkers et al 36. postulate that Mg-banding in N. pachyderma is attributed to the chamber formation process which gives rise to the lamellar calcite patterns often observed in N. pachyderma .…”

Section: Discussionmentioning

confidence: 99%

“…If Mg-banding were due to chamber formation only, then we would expect one high Mg-band in the F chamber. The number of Mg-bands in N. pachyderma , however, are variable from chamber-to-chamber and older chambers appear to have more Mg-bands than the younger chambers (for example, compare Figs 2e,f and 3e,f in Jonkers et al 3614.…”

Section: Discussionmentioning

confidence: 99%

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Link between light-triggered Mg-banding and chamber formation in the planktic foraminifera Neogloboquadrina dutertrei

et al. 2017

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The relationship between seawater temperature and the average Mg/Ca ratios in planktic foraminifera is well established, providing an essential tool for reconstructing past ocean temperatures. However, many species display alternating high and low Mg-bands within their shell walls that cannot be explained by temperature alone. Recent experiments demonstrate that intrashell Mg variability in Orbulina universa, which forms a spherical terminal shell, is paced by the diurnal light/dark cycle. Whether Mg-heterogeneity is also diurnally paced in species with more complex shell morphologies is unknown. Here we show that high Mg/Ca-calcite forms at night in cultured specimens of the multi-chambered species Neogloboquadrina dutertrei. Our results demonstrate that N. dutertrei adds a significant amount of calcite, and nearly all Mg-bands, after the final chamber forms. These results have implications for interpreting patterns of calcification in N. dutertrei and suggest that diurnal Mg-banding is an intrinsic component of biomineralization in planktic foraminifera.

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Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Link between light-triggered Mg-banding and chamber formation in the planktic foraminifera Neogloboquadrina dutertrei

et al. 2017

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“…Observed Mg/Ca ratio banding in N. incompta appeared similar to that reported in N . dutertrei (Fehrenbacher & Martin, ), N. pachyderma (Jonkers et al, ), and other species of planktic foraminifera (e.g., Eggins et al, ; Sadekov et al, ; Spero et al, ). As it occurred in culture‐grown calcite, banding cannot be the product of migration within the water column with vertical changes in temperature and/or pH (Jonkers et al, ; Spero et al, ).…”

Section: Discussionmentioning

confidence: 99%

Relationships Between Temperature, pH, and Crusting on Mg/Ca Ratios in Laboratory‐Grown Neogloboquadrina Foraminifera

et al. 2017

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Mg/Ca ratio paleothermometry in foraminifera is an important tool for the reconstruction and interpretation of past environments. However, existing Mg/Ca:temperature relationships for planktic species inhabiting middle‐ and high‐latitude environments are limited by a lack of information about the development and impact of low‐Mg/Ca ratio “crusts” and the influence of the carbonate system on Mg/Ca ratios in these groups. To address this, we cultured individual specimens of Neogloboquadrina incompta and Neogloboquadrina pachyderma in seawater across a range of temperature (6°–12°C) and pH (7.4–8.2). We found by laser ablation inductively couple mass spectrometry analyses of shells that culture‐grown crust calcite in N. incompta had a lower Mg/Ca ratio than ontogenetic calcite formed at the same temperature, suggesting that temperature is not responsible for the low‐Mg/Ca ratio of neogloboquadrinid crusts. The Mg/Ca:temperature relationship for ontogenetic calcite in N. incompta was consistent with the previously published culture‐based relationship, and no significant relationship was found between Mg/Ca ratios and pH in this species. However, the Mg/Ca ratio in laboratory‐cultured N. pachyderma was much higher than that reported in previous core top and sediment trap samples, due to lack of crust formation in culture. Application of our ontogenetic calcite‐specific Mg/Ca:temperature relationships to fossil N. pachyderma and N. incompta from five intervals in cores from the Santa Barbara Basin and the Bering Sea shows that excluding crust calcite in fossil specimens may improve Mg/Ca‐based temperature estimates.

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Environmental Controls on Mg/Ca in Neogloboquadrina incompta: A Core‐Top Study From the Subpolar North Atlantic

Morley

Babila

Wright

et al. 2017

Geochem Geophys Geosyst

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Magnesium/calcium paleothermometry is an established tool for reconstructing past surface and deep‐sea temperatures. However, our understanding of nonthermal environmental controls on the uptake of Mg into the calcitic lattice of foraminiferal tests remains limited. Here we present a combined analysis of multiple trace element/calcium ratios and stable isotope (δ18O and δ13C) geochemistry on the subpolar planktonic foraminifera Neogloboquadrina incompta to assess the validity of Mg/Ca as a proxy for surface ocean temperature. We identify small size‐specific offsets in Mg/Ca and δ18Oc values for N. incompta that are consistent with depth habitat migration patterns throughout the life cycle of this species. Additionally, an assessment of nonthermal controls on Mg/Ca values reveals that (1) the presence of volcanic ash, (2) the addition of high‐Mg abiotic overgrowths, and (3) ambient seawater carbonate chemistry can have a significant impact on the Mg/Ca‐to‐temperature relationship. For carbonate‐ion concentrations of values > 200 μmol kg−1, we find that temperature exerts the dominant control on Mg/Ca values, while at values < 200 μmol kg−1 the carbonate‐ion concentration of seawater increases the uptake of Mg, thereby resulting in higher‐than‐expected Mg/Ca values at low temperatures. We propose two independent correction schemes to remove the effects of volcanic ash and carbonate‐ion concentration on Mg/Ca values in N. incompta within the calibration data set. Applying the corrections improves the fidelity of past ocean temperature reconstructions.

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Chamber formation leads to Mg/Ca banding in the planktonic foraminifer Neogloboquadrina pachyderma

Cited by 41 publications

References 49 publications

Link between light-triggered Mg-banding and chamber formation in the planktic foraminifera Neogloboquadrina dutertrei

Link between light-triggered Mg-banding and chamber formation in the planktic foraminifera Neogloboquadrina dutertrei

Relationships Between Temperature, pH, and Crusting on Mg/Ca Ratios in Laboratory‐Grown Neogloboquadrina Foraminifera

Environmental Controls on Mg/Ca in Neogloboquadrina incompta: A Core‐Top Study From the Subpolar North Atlantic

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