Element ∕ Ca ratios in Nodosariida (Foraminifera) and their potential application for paleoenvironmental reconstructions
<p>The chemical composition of foraminiferal shells is a well-known tool in paleoceanography to reconstruct past environments and climate. Their application is based on the relation between environmental variables and the concentration of elements incorporated or stable isotope fractionation d...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-10-01
|
| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/20/4043/2023/bg-20-4043-2023.pdf |
| Summary: | <p>The chemical composition of foraminiferal shells is a well-known
tool in paleoceanography to reconstruct past environments and climate. Their
application is based on the relation between environmental variables and the
concentration of elements incorporated or stable isotope fractionation
during calcification. The vast majority of these so-called
proxy relationships are based on the foraminiferal order of the Rotaliida,
which, for example, encompasses all living planktonic species. However, there
are more orders of foraminifera with calcifying members, some of which
have fundamentally different biomineralization pathways, such as the
Nodosariida, the Polymorphinida and the Vaginulinida. All these belong to
the class of the Nodosariata and produce calcite shells, which may serve as
carriers of paleoenvironmental and climate signals. The microstructures of
these shells and overall morphology of these foraminifera strongly deviate
from the Rotaliida, suggesting that their elemental and stable isotopic
composition do not necessarily respond similarly to environmental
parameters. A potential advantage of the Nodosariata is that they appear
considerably earlier in the fossil record (Carboniferous) than the Rotaliida
(Jurassic), thereby possibly extending the range of foraminifer-based
paleoceanographic reconstructions considerably. To test the potential
application of Nodosariata foraminifera as paleoproxies, we investigated
incorporation of 5 elements in 11 species as a function of environmental
parameters from a transect sampled in the Gulf of Mexico. Their element
composition (B <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="e653eaf840568ee76bb20ba3bf368ae0"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-4043-2023-ie00004.svg" width="8pt" height="14pt" src="bg-20-4043-2023-ie00004.png"/></svg:svg></span></span> Ca, Na <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="57ee8123d9c9aefcf23d9c7f6463c158"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-4043-2023-ie00005.svg" width="8pt" height="14pt" src="bg-20-4043-2023-ie00005.png"/></svg:svg></span></span> Ca, Mg <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="93e47eb16cb371fe6916d3191efc4f1d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-4043-2023-ie00006.svg" width="8pt" height="14pt" src="bg-20-4043-2023-ie00006.png"/></svg:svg></span></span> Ca, Sr <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="073414a2b77546d8d5847ae97897d626"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-4043-2023-ie00007.svg" width="8pt" height="14pt" src="bg-20-4043-2023-ie00007.png"/></svg:svg></span></span> Ca and Ba <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="36bd7baae116a5efc17e692d563c2b51"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-4043-2023-ie00008.svg" width="8pt" height="14pt" src="bg-20-4043-2023-ie00008.png"/></svg:svg></span></span> Ca) shows a distinct
geochemical signature for these foraminifera, different to that of members of
other foraminiferal orders. Results also show an increase in Mg <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="fb147fccdcf98a9911cf3d26a8f6dc33"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-4043-2023-ie00009.svg" width="8pt" height="14pt" src="bg-20-4043-2023-ie00009.png"/></svg:svg></span></span> Ca values
with increasing temperature, similar to that known for the Rotaliida, which
suggest that Nodosariata shells might be useful for paleotemperature
reconstructions. The difference in Mg <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="880d1b22cfae9b4167ff115d05c6894c"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-4043-2023-ie00010.svg" width="8pt" height="14pt" src="bg-20-4043-2023-ie00010.png"/></svg:svg></span></span> Ca–temperature calibration in
Nodosariata compared to Rotaliida, with the large differences in their
morphology, shell microstructures and overall geochemical composition,
suggests that the Mg <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="3af55808dad7e355d8e0b0b2a0272ce7"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-4043-2023-ie00011.svg" width="8pt" height="14pt" src="bg-20-4043-2023-ie00011.png"/></svg:svg></span></span> Ca-to-temperature relationship is partly independent of
the exact calcification mechanism. We compare Mg <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M11" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="165b352473919034209a9d51d0eaf41d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-4043-2023-ie00012.svg" width="8pt" height="14pt" src="bg-20-4043-2023-ie00012.png"/></svg:svg></span></span> Ca–temperature
sensitivities across foraminiferal orders and describe a relationship
between the average Mg <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="6bfc4ae3491d603d986b6e1d0e6866cf"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-4043-2023-ie00013.svg" width="8pt" height="14pt" src="bg-20-4043-2023-ie00013.png"/></svg:svg></span></span> Ca and the sensitivity of the Mg <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="8550e2e9970f84100ffbfa4da4f4f543"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-4043-2023-ie00014.svg" width="8pt" height="14pt" src="bg-20-4043-2023-ie00014.png"/></svg:svg></span></span> Ca–temperature
calibration. For other elements, the variability across orders is smaller
compared to that in Mg <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="539a58614ea8688159b8effbc6d3da8d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-4043-2023-ie00015.svg" width="8pt" height="14pt" src="bg-20-4043-2023-ie00015.png"/></svg:svg></span></span> Ca, which results in more similar El <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="7572a9d7afeaa92ba0e8bb6f686362bd"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-4043-2023-ie00016.svg" width="8pt" height="14pt" src="bg-20-4043-2023-ie00016.png"/></svg:svg></span></span> Ca–environmental
calibrations.</p> |
|---|---|
| ISSN: | 1726-4170 1726-4189 |