Exploring macroevolutionary links in multi-species planktonic foraminiferal Mg∕Ca and <i>δ</i><sup>18</sup>O from 15 Ma to recent
<p>The ratio of the trace element <span class="inline-formula">Mg</span> over <span class="inline-formula">Ca</span> (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-02-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/22/1095/2025/bg-22-1095-2025.pdf |
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| Summary: | <p>The ratio of the trace element <span class="inline-formula">Mg</span> over <span class="inline-formula">Ca</span> (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Mg</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="6fecc37bb20730e40ab6853772ac401b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-22-1095-2025-ie00004.svg" width="37pt" height="14pt" src="bg-22-1095-2025-ie00004.png"/></svg:svg></span></span>) and the oxygen isotopic composition (<span class="inline-formula"><i>δ</i><sup>18</sup>O</span>) of foraminiferal calcite are widely employed for reconstructing past ocean temperatures, although geochemical signals are also influenced by several other factors that vary temporally and spatially. Here, we analyse a global dataset of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Mg</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="d1f58fc3a76bb75dfaa8c6e5d7932caa"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-22-1095-2025-ie00005.svg" width="37pt" height="14pt" src="bg-22-1095-2025-ie00005.png"/></svg:svg></span></span> and <span class="inline-formula"><i>δ</i><sup>18</sup>O</span> data of 59 middle Miocene to recent species of planktonic foraminifera from a wide range of depth habitats, many of which have never been analysed before for <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M11" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Mg</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="f1779bf689ab561aec68d69179b18b1f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-22-1095-2025-ie00006.svg" width="37pt" height="14pt" src="bg-22-1095-2025-ie00006.png"/></svg:svg></span></span>. We investigate the extent to which <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Mg</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="93d9205225782a1f8841d5931bc9119e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-22-1095-2025-ie00007.svg" width="37pt" height="14pt" src="bg-22-1095-2025-ie00007.png"/></svg:svg></span></span> and <span class="inline-formula"><i>δ</i><sup>18</sup>O</span> covary through time and space and identify several sources of mismatch between the two proxies. Once the data are adjusted for long-term non-thermal factors, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Mg</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="c87962a05d897c98979bd6bf78320de6"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-22-1095-2025-ie00008.svg" width="37pt" height="14pt" src="bg-22-1095-2025-ie00008.png"/></svg:svg></span></span> and <span class="inline-formula"><i>δ</i><sup>18</sup>O</span> are overall positively correlated in a way consistent with temperature being the dominant controller through both space and time and across many different species, including deep dwellers. However, we identify several species with systematic offsets in <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M16" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Mg</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="6eca209e28e0ae961085726bead065fe"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-22-1095-2025-ie00009.svg" width="37pt" height="14pt" src="bg-22-1095-2025-ie00009.png"/></svg:svg></span></span> values, to which multispecies calibrations should be applied with caution. We can track the appearance of such offsets through ancestor-descendent species over the last 15 Myr and propose that the emergence of these offsets may be the geochemical expression of evolutionary innovations. We find that virtually all of the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M17" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">Mg</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="92be5ea42e05a3e49a765741d834c1a7"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-22-1095-2025-ie00010.svg" width="37pt" height="14pt" src="bg-22-1095-2025-ie00010.png"/></svg:svg></span></span>- and <span class="inline-formula"><i>δ</i><sup>18</sup>O</span>-derived temperatures from the commonly used genera <i>Globigerinoides</i> and <i>Trilobatus</i> are within uncertainty of each other, highlighting the utility of these species for paleoceanographic reconstructions. Our results highlight the potential of leveraging information from species lineages to improve sea surface temperature reconstruction from planktonic foraminifera over the Cenozoic.</p> |
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| ISSN: | 1726-4170 1726-4189 |