Paleoceanography and ice sheet variability offshore Wilkes Land, Antarctica – Part 2: Insights from Oligocene–Miocene dinoflagellate cyst assemblages

Bijl, Peter K.; Houben, Alexander J. P.; Hartman, Julian D.; Pross, Jörg; Salabarnada, Ariadna; Escutia, Carlota; Sangiorgi, Francesca

doi:10.5194/cp-14-1015-2018

Cited by 59 publications

(81 citation statements)

References 81 publications

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“…Together with the companion papers by Salabarnada et al 2018and Bijl et al (2018a) on the lithology and dinocyst assemblages of Site U1356, we contribute significantly to the limited knowledge that exists on Oligocene-Miocene paleoceanographic conditions close to the Antarctic margin.…”

Section: Introductionmentioning

confidence: 56%

“…1). Today, this site is south of the Antarctic PF and is under the influence of by Antarctic Bottom Waters (AABW), Lower Compo- II III IV V VI VII VIII IX I 0 4 8 1 2 Hiatus (Bijl et al, 2018b) Bioturbated claystones…”

Section: Site Descriptionmentioning

confidence: 99%

“…Lithology, TEX 86 values, and GDGT-2 / GDGT-3 ratios of Hole U1356A plotted against depth (m b.s.f.) with units according to Escutia et al (2011) and chronostratigraphic tie points and paleomagnetic polarities obtained from Tauxe et al (2012), adjusted by Crampton et al (2016) and Bijl et al (2018b). Depositional facies and interpretation are indicated with colors following Salabarnada et al 2018; see legend to the right.…”

Section: Site Descriptionmentioning

confidence: 99%

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Paleoceanography and ice sheet variability offshore Wilkes Land, Antarctica – Part 3: Insights from Oligocene–Miocene TEX<sub>86</sub>-based sea surface temperature reconstructions

et al. 2018

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Abstract. The volume of the Antarctic continental ice sheet(s) varied substantially during the Oligocene and Miocene (∼34–5 Ma) from smaller to substantially larger than today, both on million-year and on orbital timescales. However, reproduction through physical modeling of a dynamic response of the ice sheets to climate forcing remains problematic, suggesting the existence of complex feedback mechanisms between the cryosphere, ocean, and atmosphere systems. There is therefore an urgent need to improve the models for better predictions of these systems, including resulting potential future sea level change. To assess the interactions between the cryosphere, ocean, and atmosphere, knowledge of ancient sea surface conditions close to the Antarctic margin is essential. Here, we present a new TEX86-based sea surface water paleotemperature record measured on Oligocene sediments from Integrated Ocean Drilling Program (IODP) Site U1356, offshore Wilkes Land, East Antarctica. The new data are presented along with previously published Miocene temperatures from the same site. Together the data cover the interval between ∼34 and ∼11 Ma and encompasses two hiatuses. This record allows us to accurately reconstruct the magnitude of sea surface temperature (SST) variability and trends on both million-year and glacial–interglacial timescales. On average, TEX86 values indicate SSTs ranging between 10 and 21 ∘C during the Oligocene and Miocene, which is on the upper end of the few existing reconstructions from other high-latitude Southern Ocean sites. SST maxima occur around 30.5, 25, and 17 Ma. Our record suggests generally warm to temperate ocean offshore Wilkes Land. Based on lithological alternations detected in the sedimentary record, which are assigned to glacial–interglacial deposits, a SST variability of 1.5–3.1 ∘C at glacial–interglacial timescales can be established. This variability is slightly larger than that of deep-sea temperatures recorded in Mg ∕ Ca data. Our reconstructed Oligocene temperature variability has implications for Oligocene ice volume estimates based on benthic δ18O records. If the long-term and orbital-scale SST variability at Site U1356 mirrors that of the nearby region of deep-water formation, we argue that a substantial portion of the variability and trends contained in long-term δ18O records can be explained by variability in Southern high-latitude temperature and that the Antarctic ice volume may have been less dynamic than previously thought. Importantly, our temperature record suggests that Oligocene–Miocene Antarctic ice sheets were generally of smaller size compared to today.

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Section: Introductionmentioning

confidence: 56%

Section: Site Descriptionmentioning

confidence: 99%

Section: Site Descriptionmentioning

confidence: 99%

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Paleoceanography and ice sheet variability offshore Wilkes Land, Antarctica – Part 3: Insights from Oligocene–Miocene TEX<sub>86</sub>-based sea surface temperature reconstructions

et al. 2018

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“…The early to mid‐Miocene represents an essential period to test ice sheet models, since large benthic δ 18 O fluctuations are recorded during this time, which potentially indicate large continental‐scale AIS variability not displayed after this time (Bijl et al, ; Billups & Schrag, ; Holbourn et al, ; Langebroek et al, ; Lear et al, ; Levy et al, ; Liebrand et al, , ; Shevenell et al, ). Here, we have shown that considering modeled equilibrium states of the Miocene AIS considerably overestimates transient AIS variability.…”

Section: Discussionmentioning

confidence: 99%

Transient Variability of the Miocene Antarctic Ice Sheet Smaller Than Equilibrium Differences

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Sutter

Knorr

et al. 2019

Geophysical Research Letters

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During the early to mid‐Miocene, benthic δ18O records indicate large ice volume fluctuations of the Antarctic ice sheet (AIS) on multiple timescales. Hitherto, research has mainly focused on how CO2 and insolation changes control an equilibrated AIS. However, transient AIS dynamics remain largely unexplored. Here, we study Miocene AIS variability, using an ice sheet‐shelf model forced by climate model output with various CO2 levels and orbital conditions. Besides equilibrium simulations, we conduct transient experiments, gradually changing the forcing climate state over time. We show that transient AIS variability is substantially smaller than equilibrium differences. This reduces the contribution of the AIS to δ18O fluctuations by more than two thirds on a 40‐kyr timescale, hence requiring a larger contribution by deep‐sea‐temperature variability. The growth rates are much slower than the decay rates, which ensures variability around a preferred small state. Finally, if the bedrock topography enlarges the West Antarctic land surface, AIS self‐sustenance increases.

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“…However, Scher et al () propose a tectonic northward shifting of the already deep Tasmanian Gateway into a stronger wind system around 33.5 Ma, triggering the onset of the ACC ~30 Ma. Recent studies suggest that the ACC did not reach its present‐day vigor before ~11 Ma (Bijl et al, ; Sangiorgi et al, ).…”

Section: Introductionmentioning

confidence: 99%

Tectonic, Oceanographic, and Climatic Controls on the Cretaceous‐Cenozoic Sedimentary Record of the Australian‐Antarctic Basin

et al. 2019

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Understanding the patterns and characteristics of sedimentary deposits on the conjugate Australian‐Antarctic margins is critical to reveal the Cretaceous‐Cenozoic tectonic, oceanographic, and climatic conditions in the basin. However, unraveling its evolution has remained difficult due to the different seismic stratigraphic interpretations on each margin and sparse drill sites. Here, for the first time, we collate all available seismic reflection profiles on both margins and use newly available offshore drilling data to develop a consistent seismic stratigraphic framework across the Australian‐Antarctic basins. We find sedimentation patterns similar in structure and thickness, prior to the onset of Antarctic glaciation, enabling the basinwide correlation of four major sedimentary units and their depositional history. We interpret that during the warm and humid Late Cretaceous (~83–65 Ma), large onshore river systems on both Australia and Antarctica resulted in deltaic sediment deposition offshore. We interpret that the onset of clockwise bottom currents during the early Paleogene (~58–48 Ma) formed prominent sediment drift deposits along both continental rises. We suggest that these currents strengthened and progressed farther east through the Eocene. Coevally, global cooling (<48 Ma) and progressive aridification led to a large‐scale decrease in sediment input from both continents. Two major Eocene hiatuses recovered by the Integrated Ocean Discovery Program site U1356A at the Antarctic continental slope likely formed during this preglacial phase of low sedimentation and strong bottom currents. Our results can be used to constrain future paleo‐oceanographic modeling of this region and aid the understanding of the oceanographic changes accompanying the transition from a greenhouse to icehouse world.

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Paleoceanography and ice sheet variability offshore Wilkes Land, Antarctica – Part 2: Insights from Oligocene–Miocene dinoflagellate cyst assemblages

Cited by 59 publications

References 81 publications

Paleoceanography and ice sheet variability offshore Wilkes Land, Antarctica – Part 3: Insights from Oligocene–Miocene TEX<sub>86</sub>-based sea surface temperature reconstructions

Paleoceanography and ice sheet variability offshore Wilkes Land, Antarctica – Part 3: Insights from Oligocene–Miocene TEX<sub>86</sub>-based sea surface temperature reconstructions

Transient Variability of the Miocene Antarctic Ice Sheet Smaller Than Equilibrium Differences

Tectonic, Oceanographic, and Climatic Controls on the Cretaceous‐Cenozoic Sedimentary Record of the Australian‐Antarctic Basin

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Paleoceanography and ice sheet variability offshore Wilkes Land, Antarctica – Part 2: Insights from Oligocene–Miocene dinoflagellate cyst assemblages

Cited by 59 publications

References 81 publications

Paleoceanography and ice sheet variability offshore Wilkes Land, Antarctica – Part 3: Insights from Oligocene–Miocene TEX&lt;sub&gt;86&lt;/sub&gt;-based sea surface temperature reconstructions

Paleoceanography and ice sheet variability offshore Wilkes Land, Antarctica – Part 3: Insights from Oligocene–Miocene TEX&lt;sub&gt;86&lt;/sub&gt;-based sea surface temperature reconstructions

Transient Variability of the Miocene Antarctic Ice Sheet Smaller Than Equilibrium Differences

Tectonic, Oceanographic, and Climatic Controls on the Cretaceous‐Cenozoic Sedimentary Record of the Australian‐Antarctic Basin

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Paleoceanography and ice sheet variability offshore Wilkes Land, Antarctica – Part 3: Insights from Oligocene–Miocene TEX<sub>86</sub>-based sea surface temperature reconstructions

Paleoceanography and ice sheet variability offshore Wilkes Land, Antarctica – Part 3: Insights from Oligocene–Miocene TEX<sub>86</sub>-based sea surface temperature reconstructions