Calcareous nannoplankton response to early Eocene warmth, Southwest Pacific Ocean

Shepherd, Claire L.; Kulhanek, Denise K.; Hollis, Christopher J.; Morgans, Hugh E. G.; Strong, C. P.; Pascher, K.M.; Zachos, James C

doi:10.1016/j.marmicro.2021.101992

Cited by 5 publications

(18 citation statements)

References 74 publications

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“…Our statistical approach allowed us to identify two main sedimentation regimes (in line with Hollis et al, 1997), namely a sedimentation rate of ~0.5 cm/ kyr between 55.4 ± 0.6 Ma and 41.8 ± 0.1 Ma and of ~2.15 cm/ kyr between 41.8 ± 0.1 Ma and 26.0 ± 0.1 Ma (Figure 2). Shepherd et al (2021) recently mentioned two hiatuses at Site 277 in the early and middle Eocene that we do not observe with our statistical model. This likely relies on the fact that our linear regressions are based on several biostratigraphic data points.…”

Section: Sample Agescontrasting

confidence: 98%

“…Scanning electron microscopy (SEM) observations (Figure 3) have been used to assess the preservation state of benthic and planktonic foraminifera. As evidenced by previous studies (e.g., Hollis et al, 2015;Shepherd et al, 2021), planktonic foraminifera from Site 277 are characterized by a "frosty" texture (Sexton et al, 2006), resulting from minor authigenic calcite recrystallization after the deposition of the test on the seafloor and/or during their sinking through the water column (Figures 3A,B). Benthic foraminifera show a smoother texture without visible secondary calcite recrystallization.…”

Section: Scanning Electron Microscopy Imaging: Test Preservationsupporting

confidence: 66%

“…Age estimations for each sample have been calculated using the biochronological data from Hollis et al (1997) for Site 277 and updated with the recently published nannofossil data of Shepherd et al (2021) for the Eocene interval. Data of Hollis et al (1997) were recalibrated to the GTS 2012 (Gradstein et al, 2012) (see Supplementary Material S2).…”

Section: Age Model and Sedimentation Rate Calculationsmentioning

confidence: 99%

“…There is significant evidence that the development of the ACC played a major role in cooling and keeping Antarctica cool (e.g., Kennett, 1977;Kennett and Exon, 2004;Sauermilch et al, 2019Sauermilch et al, , 2021. In this study, we investigate the role that other currents such as the proto-East Australian Current and the proto-Ross gyre (e.g., Nelson and Cooke, 2001;Bijl et al, 2009;Pascher et al, 2015;Sauermilch et al, 2021;Shepherd et al, 2021) played on the ocean heat fluxes, ocean redox state and primary productivity during the Eocene-Oligocene cooling.…”

Section: Introductionmentioning

confidence: 99%

“…Antarctica and the surrounding Southern Ocean have been a significant focus of the last decades given their high sensitivity to cooling and glaciation during the Eocene-Oligocene (e.g., Kennett et al, 1975;Nelson and Cooke, 2001;Zachos et al, 2001;Stickley et al, 2004;Bijl et al, 2009;Bohaty et al, 2012;Hollis et al, 2012Hollis et al, , 2015Scher et al, 2014Scher et al, , 2015Pascher et al, 2015;Hodel et al, 2021;Sauermilch et al, 2021;Shepherd et al, 2021). Located at the outlet of the Tasmanian gateway, the DSDP Site 277 on the Campbell Plateau (Figure 1) was drilled specifically to investigate the role played by the Antarctic Circumpolar Current (ACC) in the thermal isolation of Antarctica from tropical heat fluxes (e.g., Kennett et al, 1975) (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

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Eocene-Oligocene southwest Pacific Ocean paleoceanography new insights from foraminifera chemistry (DSDP site 277, Campbell Plateau)

et al. 2022

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Despite its major role in the Earth’s climate regulation, the evolution of high-latitude ocean dynamics through geological time remains unclear. Around Antarctica, changes in the Southern Ocean (SO) circulation are inferred to be responsible for cooling from the late Eocene and glaciation in the early Oligocene. Here, we present a geochemical study of foraminifera from DSDP Site 277 (Campbell Plateau), to better constrain thermal and redox evolution of the high latitude southwest Pacific Ocean during this time interval. From 56 to 48 Ma, Mg/Ca- and δ18O-paleothermometers indicate high surface and bottom water temperatures (24–26°C and 12–14°C, respectively), while weak negative Ce anomalies indicate poorly oxygenated bottom waters. This is followed by a cooling of ∼4° between 48 and 42 Ma, possibly resulting from a weakening of a proto-EAC (East Australian Current) and concomitant strengthening of a proto-Ross gyre. This paleoceanographic change is associated with better ventilation at Site 277, recorded by an increasing negative Ce anomaly. Once this proto-Ross gyre was fully active, increasing biogenic sedimentation rates and decreasing Subbotina sp. δ13C values indicate enhanced productivity. This resulted in a shoaling of the oxygen penetration in the sediment pile recorded by increasing the foraminiferal U/Ca ratio. The negative Ce anomaly sharply increased two times at ∼35 and ∼31 Ma, indicating enhanced seawater ventilation synchronously with the opening of the Tasmanian and Drake Passage gateways, respectively. The Oligocene glaciation is recorded by a major increase of bottom seawater δ18O during the EOT (Eocene-Oligocene Transition) while Mg/Ca-temperatures remain rather constant. This indicates a significant ice control on the δ18O record.

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Section: Sample Agescontrasting

confidence: 98%