Recent advances in the study of Eocene planktonic foraminifera

Pearson, Paul Nicholas; Olsson, Richard K.; Huber, Brian T.; Hemleben, Christoph; Berggren, William A.; Coxall, Helen K.; Fuček, Vlasta Premec; Silvá, Isabella Premoli; Wade, Bridget S.

doi:10.11137/2006_1_357-358

Cited by 21 publications

(32 citation statements)

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“…Assemblages were examined using a Zeiss binocular stereo light microscope. Taxonomic determinations follow Pearson et al (2006) and Wade et al (2018).…”

Section: Foraminifera Sample Preparation and Planktonic Foraminifera ...mentioning

confidence: 99%

Calcareous nannofossils across the Eocene-Oligocene transition at Site 756 (Ninetyeast Ridge, Indian Ocean): implications for biostratigraphy and paleoceanographic clues

Viganò¹,

Coxall²,

Holmström³

et al. 2023

nos

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The timing and modalities of calcareous phytoplankton community and evolutionary responses to the Eocene-Oligocene transition (EOT, ~ 34 Ma) are still under-investigated. In order to better constrain the dynamics of these pelagic primary producers during the climate transition, we conducted high resolution assemblage analysis on calcareous nannofossils across a ~19 m-thick interval of nannofossil ooze at Ocean Drilling Program (ODP) Site 756 (Ninetyeast Ridge, Indian Ocean; Peirce et al. 1989) (paleolatitude ~43°S; Zachos et al. 1992). We explored the diversity patterns against a new integrated planktonic foraminifera and calcareous nannofossil biostratigraphy produced for the site, as well as new benthic foraminifera stable isotope (C, O) record, which documents ocean-climate changes, and provides independent chemostratigraphy. The study section spans nannofossil Zones NP20-NP23 (equivalent to CNE20-CNO4) and lasts 5.6 Myr. The results show that the hankeninid extinction falls within the ~4.5 m-thick EOT isotopic interval (0.67 m below the base of the second positive δ 18 O shift -EOIS), which is consistent with previous studies, making Hole 756C one of a few sites globally boasting both the familiar stepped δ 18 O and δ 13 C structure of the EOT and the primary biostratigraphic marker defining the base of the Oligocene. A series of potentially useful new calcareous nannofossil bioevents were identified that could help improve dating and correlation of this crucial interval. In this context, changes in calcareous nannofossil assemblages observed across EOT are interpreted in terms of modifications of paleoecological parameters that typically control the abundance and distribution of different taxa. Variations in sea surface temperature and nutrient availability are considered to be the most likely triggers for the calcareous phytoplankton changes observed across EOT. Specifically, our data suggest that increased nutrients in the mixed layer played a key role in shaping the late Eocene -early Oligocene calcareous nannofossil assemblages.

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“…Assemblages were examined using a Zeiss binocular stereo light microscope. Taxonomic determinations follow Pearson et al (2006) and Wade et al (2018).…”

Section: Foraminifera Sample Preparation and Planktonic Foraminifera ...mentioning

confidence: 99%

Calcareous nannofossils across the Eocene-Oligocene transition at Site 756 (Ninetyeast Ridge, Indian Ocean): implications for biostratigraphy and paleoceanographic clues

Viganò¹,

Coxall²,

Holmström³

et al. 2023

nos

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“…For this study, each sample in both size fractions (>63 μm and >180 μm) was further split using a microsplitter until approximately 300 individuals were present on the picking tray, with a minimum cutoff of 200 specimens. All individuals in the subsample were then picked to avoid bias as a result of uneven distribution on the tray and identified to the genus level (Supplementary Tables 2–4) based on published taxonomy (Pearson et al 2006; Wade et al 2018).…”

Section: Methodsmentioning

confidence: 99%

“…To understand diversity changes further, we then classified all genera into morphogroups (Supplementary Tables 5, 6) adapted from previous classifications (Aze et al 2011) and depth habitats (Supplementary Tables 7, 8). We based morphogroup classifications on morphological traits (Supplementary Table 9) and depth habitats (Supplementary Table 10) on published ecological inferences obtained from stable isotope measurements (summarized in Pearson et al 2006; Wade et al 2018). Relative abundances and effective diversity curves were than calculated for each genus, morphogroup, and ecogroup.…”

Section: Methodsmentioning

confidence: 99%

Small but mighty: how overlooked small species maintain community structure through middle Eocene climate change

Kearns¹,

Bohaty²,

Edgar³

et al. 2022

Paleobiology

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Understanding current and future biodiversity responses to changing climate is pivotal as anthropogenic climate change continues. This understanding is complicated by the multitude of available metrics to quantify dynamics and by biased sampling protocols. Here, we investigate the impact of sampling protocol strategies using a data-rich fossil record to calculate effective diversity using Hill numbers for the first time on Paleogene planktonic foraminifera. We sample 22,830 individual tests, in two different size classes, across a 7 Myr time slice of the middle Eocene featuring a major transient warming event, the middle Eocene climatic optimum (MECO; ~40 Ma), at study sites in the midlatitude North Atlantic. Using generalized additive models, we investigate community responses to climatic fluctuations. After correcting for any effects of fossil fragmentation, we show a peak in generic diversity in the early and middle stages of the MECO as well as divergent trajectories between the typical size-selected community (>180 μm) and a broader assemblage, including smaller genera (>63 μm). Assemblages featuring smaller genera are more resilient to the climatic fluctuations of the MECO than those assemblages that feature only larger genera, maintaining their community structure at the reference Hill numbers for Shannon's and Simpson's indices. These results raise fundamental questions about how communities respond to climate excursions. In addition, our results emphasize the need to design studies with the aim of collecting the most inclusive data possible to allow detection of community changes and determine which species are likely to dominate future environments.

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“…Quaternary and Neogene planktonic foraminifer taxonomy follow Kennett and Srinivasan (1983), Spiegler andJansen (1989), andSpiegler (1996). Paleogene planktonic foraminifer taxonomy follow Wade et al ( 2011) modified from Pearson et al (2006) and Wade et al (2018).…”

Section: Planktonic Foraminiferal Taxonomy and Biozonation Schemesmentioning

confidence: 99%

“…Because of this, local zonation schemes of ODP Legs 104 and 162 are utilized for the Miocene to Quaternary (Spiegler and Jansen, 1989;Spiegler, 1996). Wade et al (2011) modified from Pearson et al (2006) zonation schemes are utilized for the Paleocene-Oligocene.…”

Section: Planktonic Foraminiferal Taxonomy and Biozonation Schemesmentioning

confidence: 99%

Expedition 396 methods

Berndt¹,

Zarikian²,

Agarwal³

et al. 2023

Proceedings of the International Ocean Discovery Program

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publications.iodp.org • 3 known because of the deviation of the pipe below the ship, which can vary depending on water currents, tides, and water depth; the hole position is thus known typically within 10 m accuracy.Drilling sites were numbered according to the series that began with the first site drilled by the D/V Glomar Challenger in 1968. Starting with Integrated Ocean Drilling Program Expedition 301, the prefix "U" designates sites occupied by JOIDES Resolution. When drilling multiple holes at a site, hole locations are typically offset from each other by ~20 m. During Expedition 396, we offset holes at an average of 115 m, except for Site U1570, where holes were offset as far as 1772 m. Site U1570 was approved by EPSP as a 2 km long "ribbon" or transect west of Site U1569 with start and end coordinates. This ribbon provided an alternate coring strategy to Site U1569, where deep stratigraphic targets were outcropping at shallower subseafloor depths. A letter suffix distinguishes each hole drilled at the same site. The first hole drilled is assigned the site number modified by the suffix "A," the second hole takes the site number and the suffix "B," and so forth. During Expedition 396, 21 holes were drilled at 10 sites (U1565-U1574; see Figure F4 in the Expedition 396 summary chapter [Planke et al., 2023a]).

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Recent advances in the study of Eocene planktonic foraminifera

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Cited by 21 publications

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Calcareous nannofossils across the Eocene-Oligocene transition at Site 756 (Ninetyeast Ridge, Indian Ocean): implications for biostratigraphy and paleoceanographic clues

Calcareous nannofossils across the Eocene-Oligocene transition at Site 756 (Ninetyeast Ridge, Indian Ocean): implications for biostratigraphy and paleoceanographic clues

Small but mighty: how overlooked small species maintain community structure through middle Eocene climate change

Expedition 396 methods

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