The Paleocene record of marine diatoms in deep-sea sediments

Renaudie, Johan; Drews, E A; Böhne, Simon

doi:10.5194/fr-21-183-2018

“…Diatoms were likely key players in the ocean Si cycle in the Early Cenozoic (Conley et al, 2017; Renaudie et al, 2018), so we can use insights from the modern ocean to guide our interpretations. Today, sea surface δ 30 Si is primarily driven by diatom Si uptake and precipitation of their frustules.…”

Section: Discussionmentioning

confidence: 99%

Constraints on Earth System Functioning at the Paleocene‐Eocene Thermal Maximum From the Marine Silicon Cycle

Fontorbe

¹

,

Frings

²

,

Rocha³

et al. 2020

Paleoceanog and Paleoclimatol

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The Paleocene-Eocene Thermal Maximum (PETM, ca. 56 Ma) is marked by a negative carbon isotope excursion (CIE) and increased global temperatures. The CIE is thought to result from the release of 13 C-depleted carbon, although the source(s) of carbon and triggers for its release, its rate of release, and the mechanisms by which the Earth system recovered are all debated. Many of the proposed mechanisms for the onset and recovery phases of the PETM make testable predictions about the marine silica cycle, making silicon isotope records a promising tool to address open questions about the PETM. We analyzed silicon isotope ratios (δ 30 Si) in radiolarian tests and sponge spicules from the Western North Atlantic (ODP Site 1051) across the PETM. Radiolarian δ 30 Si decreases by 0.6‰ from a background of 1‰ coeval with the CIE, while sponge δ 30 Si remains consistent at 0.2‰. Using a box model to test the Si cycle response to various scenarios, we find the data are best explained by a weak silicate weathering feedback, implying the recovery was mostly driven by nondiatom organic carbon burial, the other major long-term carbon sink. We find no resolvable evidence for a volcanic trigger for carbon release, or for a change in regional oceanography. Better understanding of radiolarian Si isotope fractionation and more Si isotope records spanning the PETM are needed to confirm the global validity of these conclusions, but they highlight how the coupling between the silica and carbon cycles can be exploited to yield insight into the functioning of the Earth system.

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“…These two datasets differ in that while Fraass et al was constructed from atlas sources (e.g., Olsson et al, 1999) and contains all recognized morphotaxa of the planktic foraminifera, the Aze et al (2011) dataset uses a lineage phylogeny to remove the pseudo-extinction and pseudo-origination caused by anagenetic evolution. Cenozoic radiolarian and diatom macroevolutionary rate and diversity data are from Spencer-Cervato (1999) and Renaudie et al (2018), respectively. Data here are all presented at 1 myr resolution to allow for a shared frame of reference, as previously published work is in that resolution.…”

Section: Methodsmentioning

confidence: 99%

Ecological Response of Plankton to Environmental Change: Thresholds for Extinction

Lowery

¹

,

Bown

²

,

Fraass

³

et al. 2020

Annu. Rev. Earth Planet. Sci.

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Severe climatic and environmental changes are far more prevalent in Earth history than major extinction events, and the relationship between environmental change and extinction severity has important implications for the outcome of the ongoing anthropogenic extinction event. The response of mineralized marine plankton to environmental change offers an interesting contrast to the overall record of marine biota, which is dominated by benthic invertebrates. Here, we summarize changes in the species diversity of planktic foraminifera and calcareous nannoplankton over the Mesozoic–Cenozoic and that of radiolarians and diatoms over the Cenozoic. We find that, aside from the Triassic–Jurassic and Cretaceous–Paleogene mass extinction events, extinction in the plankton is decoupled from that in the benthos. Extinction in the plankton appears to be driven primarily by majorclimatic shifts affecting water column stratification, temperature, and, perhaps, chemistry. Changes that strongly affect the benthos, such as acidification and anoxia, have little effect on the plankton or are associated with radiation. ▪ Fossilizing marine plankton provide some of the most highly temporally and taxonomically resolved records of biodiversity since the Mesozoic. ▪ The record of extinction and origination in the plankton differs from the overall marine biodiversity record in revealing ways. ▪ Changes to water column stratification and global circulation are the main drivers of plankton diversity. ▪ Anoxia, acidification, and eutrophication (which strongly influence total marine fossil diversity) are less important in the plankton.

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“…These two datasets differ in that while Fraass et al was constructed from atlas sources (e.g., Olsson et al, 1999) and contains all recognized morphotaxa of the planktic foraminifera, the Aze et al (2011) dataset uses a lineage phylogeny to remove the pseudo-extinction and pseudo-origination caused by anagenetic evolution. Cenozoic radiolarian and diatom macroevolutionary rate and diversity data are from Spencer-Cervato (1999) and Renaudie et al (2018), respectively. Data here are all presented at 1 myr resolution to allow for a shared frame of reference, as previously published work is in that resolution.…”

Section: Methodsmentioning

confidence: 99%

Ecological Response of Plankton to Environmental Change – Thresholds for Extinction

Lowery¹,

Bown²,

Fraass³

et al. 2019

Preprint

View full text Add to dashboard Cite

Severe climatic and environmental changes are far more prevalent in Earth history than major extinction events, and the relationship between environmental change and extinction severity has important implications for the outcome of the ongoing anthropogenic extinction event. The response of mineralized marine plankton to environmental change offers an interesting contrast to the overall record of marine biota, which is dominated by benthic invertebrates. Here, we summarize changes in the species diversity of planktic foraminifera and calcareous nannoplankton over the Mesozoic-Cenozoic and that of radiolarians and diatoms over the Cenozoic. We find that, aside from the Triassic-Jurassic and Cretaceous-Paleogene mass extinction events, extinction in the plankton is decoupled from that in the benthos. Extinction in the plankton appears to be driven primarily by major climatic shifts affecting water column stratification, temperature, and, perhaps, chemistry. Changes that strongly affect the benthos, like acidification and anoxia, have little effect on the plankton, or are associated with radiation.

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The Paleocene record of marine diatoms in deep-sea sediments

Cited by 14 publications

References 74 publications

Constraints on Earth System Functioning at the Paleocene‐Eocene Thermal Maximum From the Marine Silicon Cycle

Constraints on Earth System Functioning at the Paleocene‐Eocene Thermal Maximum From the Marine Silicon Cycle

Ecological Response of Plankton to Environmental Change: Thresholds for Extinction

Ecological Response of Plankton to Environmental Change – Thresholds for Extinction

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