46 results on '"Bijl, Peter K."'
Search Results
2. Late Eocene to late Oligocene terrestrial climate and vegetation change in the western Tasmanian region
- Author
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Amoo, Michael, Salzmann, Ulrich, Pound, Matthew J., Hoem, Frida S., Thompson, Nick, and Bijl, Peter K.
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- 2023
- Full Text
- View/download PDF
3. Southern Ocean control on atmospheric CO2 changes across late-Pliocene Marine Isotope Stage M2
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Hou, Suning, primary, Toebrock, Leonie, additional, van der Linden, Mart, additional, Rothstegge, Fleur, additional, Ziegler, Martin, additional, Lourens, Lucas J., additional, and Bijl, Peter K., additional
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- 2024
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- View/download PDF
4. Strength and variability of the Oligocene Southern Ocean surface temperature gradient
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Hoem, Frida S., Sauermilch, Isabel, Aleksinski, Adam K., Huber, Matthew, Peterse, Francien, Sangiorgi, Francesca, and Bijl, Peter K.
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- 2022
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- View/download PDF
5. Climate variability, heat distribution, and polar amplification in the warm unipolar "icehouse" of the Oligocene.
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Jenny, Dominique K. L. L., Reichgelt, Tammo, O'Brien, Charlotte L., Liu, Xiaoqing, Bijl, Peter K., Huber, Matthew, and Sluijs, Appy
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LAND surface temperature ,OCEAN temperature ,GLOBAL warming ,OLIGOCENE Epoch ,ATMOSPHERIC models - Abstract
The Oligocene (33.9–23.03 Ma) had warm climates with flattened meridional temperature gradients, while Antarctica retained a significant cryosphere. These may pose imperfect analogues to distant future climate states with unipolar icehouse conditions. Although local and regional climate and environmental reconstructions of Oligocene conditions are available, the community lacks synthesis of regional reconstructions. To provide a comprehensive overview of marine and terrestrial climate and environmental conditions in the Oligocene, and a reconstruction of trends through time, we review marine and terrestrial proxy records and compare these to numerical climate model simulations of the Oligocene. Results, based on the present relatively sparse data, suggest temperatures around the Equator that are similar to modern temperatures. Sea surface temperatures (SSTs) show patterns similar to land temperatures, with warm conditions at mid- and high latitudes (∼60 –90°), especially in the Southern Hemisphere (SH). Vegetation-based precipitation reconstructions of the Oligocene suggest regionally drier conditions compared to modern times around the Equator. When compared to proxy data, climate model simulations overestimate Oligocene precipitation in most areas, particularly the tropics. Temperatures around the mid- to high latitudes are generally underestimated in models compared to proxy data and tend to overestimate the warming in the tropics. In line with previous proxy-to-model comparisons, we find that models underestimate polar amplification and overestimate the Equator-to-pole temperature gradient suggested from the available proxy data. This further stresses the urgency of solving this widely recorded problem for past warm climates, such as the Oligocene. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. DINOSTRAT version 2.1-GTS2020
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Bijl, Peter K., primary
- Published
- 2024
- Full Text
- View/download PDF
7. The southward migration of the Antarctic Circumpolar Current enhanced oceanic degassing of carbon dioxide during the last two deglaciations
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Ai, Xuyuan E., primary, Thöle, Lena M., additional, Auderset, Alexandra, additional, Schmitt, Mareike, additional, Moretti, Simone, additional, Studer, Anja S., additional, Michel, Elisabeth, additional, Wegmann, Martin, additional, Mazaud, Alain, additional, Bijl, Peter K., additional, Sigman, Daniel M., additional, Martínez-García, Alfredo, additional, and Jaccard, Samuel L., additional
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- 2024
- Full Text
- View/download PDF
8. Polar amplification of orbital-scale climate variability in the early Eocene greenhouse world.
- Author
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Fokkema, Chris D., Agterhuis, Tobias, Gerritsma, Danielle, de Goeij, Myrthe, Liu, Xiaoqing, de Regt, Pauline, Rice, Addison, Vennema, Laurens, Agnini, Claudia, Bijl, Peter K., Frieling, Joost, Huber, Matthew, Peterse, Francien, and Sluijs, Appy
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EOCENE Epoch ,OCEAN temperature ,ATMOSPHERIC carbon dioxide ,CARBON cycle ,FORCED migration ,GEOLOGICAL time scales - Abstract
Climate variability is typically amplified towards polar regions. The underlying causes, notably albedo and humidity changes, are challenging to accurately quantify with observations or models, thus hampering projections of future polar amplification. Polar amplification reconstructions from the ice-free early Eocene (∼56 –48 Ma) can exclude ice albedo effects, but the required tropical temperature records for resolving timescales shorter than multi-million years are lacking. Here, we reconstruct early Eocene tropical sea surface temperature variability by presenting an up to ∼4 kyr resolution biomarker-based temperature record from Ocean Drilling Program (ODP) Site 959, located in the tropical Atlantic Ocean. This record shows warming across multiple orbitally paced carbon cycle perturbations, coeval with high-latitude-derived deep-ocean bottom waters, showing that these events represent transient global warming events (hyperthermals). This implies that orbital forcing caused global temperature variability through carbon cycle feedbacks. Importantly, deep-ocean temperature variability was amplified by a factor of 1.7–2.3 compared to the tropical surface ocean, corroborating available long-term estimates. This implies that fast atmospheric feedback processes controlled meridional temperature gradients on multi-million year, as well as orbital, timescales during the early Eocene. Our combined records have several other implications. First, our amplification factor is somewhat larger than the same metric in fully coupled simulations of the early Eocene (1.1–1.3), suggesting that models slightly underestimate the non-ice-related – notably hydrological – feedbacks that cause polar amplification of climate change. Second, even outside the hyperthermals, we find synchronous eccentricity-forced temperature variability in the tropics and deep ocean that represent global mean sea surface temperature variability of up to 0.7 °C, which requires significant variability in atmospheric p CO 2. We hypothesize that the responsible carbon cycle feedbacks that are independent of ice, snow, and frost-related processes might play an important role in Phanerozoic orbital-scale climate variability throughout geological time, including Pleistocene glacial–interglacial climate variability. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
- View/download PDF
9. Southern Ocean control on atmospheric CO2 changes across late-Pliocene Marine Isotope Stage M2.
- Author
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Hou, Suning, Toebrock, Leonie, van der Linden, Mart, Rothstegge, Fleur, Ziegler, Martin, Lourens, Lucas J., and Bijl, Peter K.
- Abstract
During the Pliocene, atmospheric CO
2 concentrations (p CO2 ) were similar to today's and global average temperature was ~3 °C higher. However, the relationships and phasing between variability in climate and p CO2 on orbital time scales are not well understood. Specifically, questions remain about the nature of a lag of p CO2 relative to benthic foraminiferal δ18 O in the late-Pliocene Marine Isotope Stage M2 (3300 kiloannum ago, ka), which was longer than during the Pleistocene. Here, we present a multi-proxy paleoceanographic reconstruction of the late-Pliocene subantarctic zone, which is today one of the major ocean sinks of atmospheric CO2 . New dinoflagellate cyst assemblage data is combined with previously published sea surface temperature reconstructions, to reveal past surface conditions, including latitudinal migrations of the subtropical front (STF) over the late-Pliocene at ODP Site 1168, offshore west Tasmania. We observe strong oceanographic variability at the STF over glacial-interglacial timescales, especially across the M2 (3320–3260 ka). By providing tight and independent age constraints from benthic foraminiferal δ18 O, we find that, much more than benthic δ18 O or local SST, latitudinal migrations of the STF are tightly coupled to p CO2 variations across the M2. Specifically, a northerly position of the STF during M2 deglaciation coincides with generally low p CO2 . We postulate that the efficiency of the Southern Ocean carbon outgassing varied strongly with migrations of the STF, and that is in part accounted for the variability in p CO2 across M2. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
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10. Late Cenozoic sea-surface-temperature evolution of the South Atlantic Ocean
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Hoem, Frida S., primary, López-Quirós, Adrián, additional, van de Lagemaat, Suzanna, additional, Etourneau, Johan, additional, Sicre, Marie-Alexandrine, additional, Escutia, Carlota, additional, Brinkhuis, Henk, additional, Peterse, Francien, additional, Sangiorgi, Francesca, additional, and Bijl, Peter K., additional
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- 2023
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11. Gateway-driven weakening of ocean gyres leads to Southern Ocean cooling
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Sauermilch, Isabel, Whittaker, Joanne M., Klocker, Andreas, Munday, David R., Hochmuth, Katharina, Bijl, Peter K., and LaCasce, Joseph H.
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- 2021
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- View/download PDF
12. Polar amplification of orbital-scale climate variability in the early Eocene greenhouse world
- Author
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Fokkema, Chris D., primary, Agterhuis, Tobias, additional, Gerritsma, Danielle, additional, de Goeij, Myrthe, additional, Liu, Xiaoqing, additional, de Regt, Pauline, additional, Rice, Addison, additional, Vennema, Laurens, additional, Agnini, Claudia, additional, Bijl, Peter K., additional, Frieling, Joost, additional, Huber, Matthew, additional, Peterse, Francien, additional, and Sluijs, Appy, additional
- Published
- 2023
- Full Text
- View/download PDF
13. Supplementary material to "Polar amplification of orbital-scale climate variability in the early Eocene greenhouse world"
- Author
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Fokkema, Chris D., primary, Agterhuis, Tobias, additional, Gerritsma, Danielle, additional, de Goeij, Myrthe, additional, Liu, Xiaoqing, additional, de Regt, Pauline, additional, Rice, Addison, additional, Vennema, Laurens, additional, Agnini, Claudia, additional, Bijl, Peter K., additional, Frieling, Joost, additional, Huber, Matthew, additional, Peterse, Francien, additional, and Sluijs, Appy, additional
- Published
- 2023
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- View/download PDF
14. DINOSTRAT version 2.0-GTS2020
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Bijl, Peter K., primary
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- 2023
- Full Text
- View/download PDF
15. Lipid-biomarker-based sea surface temperature record offshore Tasmania over the last 23 million years
- Author
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Hou, Suning, primary, Lamprou, Foteini, additional, Hoem, Frida S., additional, Hadju, Mohammad Rizky Nanda, additional, Sangiorgi, Francesca, additional, Peterse, Francien, additional, and Bijl, Peter K., additional
- Published
- 2023
- Full Text
- View/download PDF
16. Climate variability, heat distribution and polar amplification in the unipolar 'doubthouse' of the Oligocene.
- Author
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Jenny, Dominique K. L. L., Reichgelt, Tammo, O'Brien, Charlotte L., Liu, Xiaoqing, Bijl, Peter K., Huber, Matthew, and Sluijs, Appy
- Subjects
OLIGOCENE Epoch ,LAND surface temperature ,OCEAN temperature ,GLOBAL warming ,ATMOSPHERIC models - Abstract
The Oligocene (33.9–23.03 Ma) was characterised by generally warm climates, with flattened meridional temperature gradients while Antarctica retained a significant cryosphere. This makes the Oligocene an imperfect analogue to long-term future climate states with unipolar icehouse conditions. Although local and regional climate and environmental reconstructions of Oligocene conditions are available, the community lacks synthesis of regional reconstructions. In order to provide a comprehensive overview of marine and terrestrial climate and environmental conditions in the Oligocene, as well as a reconstruction of trends through time, we here review marine and terrestrial proxy records and numerical climate model simulations of the Oligocene. Results display weaker temperature gradients during the Oligocene compared to modern times, with generally warm poles and colder-than-modern temperatures around the equator. Sea surface temperatures (SSTs) show similar trends to the land temperatures, with warm temperatures around the mid and high latitudes (~60–90°) of especially the Southern Hemisphere. Vegetation-based precipitation reconstructions of the Oligocene suggest drier conditions compared to modern times, in particular around the equator. When compared to proxy-based data, climate modelling approaches overestimate Oligocene precipitation in most areas, in particular the tropics. Temperature around the mid to high latitudes is generally underestimated in models compared to proxy data and tend to overestimate the warming in the tropics. In line with previous conclusions models underestimate polar amplification and the equator-to-pole heat distribution that prevailed during the Oligocene. Despite prevalent glaciation on Antarctica, the Oligocene "icehouse" experienced warm global average temperatures while still maintaining a unipolar icehouse state. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
17. DINOSTRAT version 2.0-GTS2020
- Author
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Bijl, Peter K.
- Abstract
Mesozoic–Cenozoic organic-walled dinoflagellate cyst (dinocyst) biostratigraphy is a crucial tool for relative and numerical age control in complex ancient sedimentary systems. However, stratigraphic ranges of dinocysts are found to be strongly diachronous geographically. A global compilation of state-of-the-art calibrated regional stratigraphic ranges could assist in quantifying regional differences and evaluate underlying causes. DINOSTRAT (Bijl, 2023a; Bijl, 2023b) is an open source, iterative, community-fed database intended to house all regional chronostratigraphic calibrations of dinocyst events DINOSTRAT version 2.0-GTS2020 includes >9,450 entries of first and last occurrences (collectively called “events”) of >2,040 dinocyst taxa, and their absolute ties are now updated to the chronostratigraphic timescale of Gradstein et al., 2020. Entries are derived from 211 publications and 209 sedimentary sections. DINOSTRAT interpolates paleolatitudes of regional dinocyst events, allowing evaluation of the paleolatitudinal variability of dinocyst event ages. DINOSTRAT allows for open accessibility and searchability, on region, age, and taxon. This paper presents a selection of the data in DINOSTRAT: (1) the (paleo)latitudinal spread and evolutionary history of modern dinocyst species; (2) the evolutionary patterns and paleolatitudinal spread of dinocyst (sub)families; (3) a selection of key dinocyst events which are particularly synchronous. Although several dinocysts show – at the resolution of their calibration – quasi-synchronous event ages, indeed many species have remarkable diachroneity. DINOSTRAT provides the data storage approach by which the community can now start to relate diachroneity to (1) inadequate tie to chronostratigraphic timescales; (2) complications in taxonomic concepts and (3) ocean connectivity and/or the affinities of taxa to environmental conditions.
- Published
- 2023
18. Lipid-biomarker-based sea surface temperature record offshore Tasmania over the last 23 million years
- Author
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Hou, Suning, Lamprou, Foteini, Hoem, Frida S., Hadju, Mohammad Rizky Nanda, Sangiorgi, Francesca, Peterse, Francien, Bijl, Peter K., Marine palynology and palaeoceanography, Organic geochemistry, and Marine Palynology
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Isoprenoid tetraether lipids ,Gdgt distributions ,Wilkes land ,Early eocene ,Global and Planetary Change ,Membrane-lipids ,Palaeontology ,Stratigraphy ,Southern-ocean ,Antarctic ice-sheet ,Water-column ,Organic-matter ,Particulate matter - Abstract
The Neogene (23.04-2.58 Ma) is characterised by progressive buildup of ice volume and climate cooling in the Antarctic and the Northern Hemisphere. Heat and moisture delivery to Antarctica is, to a large extent, regulated by the strength of meridional temperature gradients. However, the evolution of the Southern Ocean frontal systems remains scarcely studied in the Neogene. Here, we present the first long-term continuous sea surface temperature (SST) record of the subtropical front area in the Southern Ocean at Ocean Drilling Program (ODP) Site 1168 off western Tasmania. This site is, at present, located near the subtropical front (STF), as it was during the Neogene, despite a 10°northward tectonic drift of Tasmania. We analysed glycerol dialkyl glycerol tetraethers (GDGTs - on 433 samples) and alkenones (on 163 samples) and reconstructed the paleotemperature evolution using TEX86 and U37k′ as two independent quantitative proxies. Both proxies indicate that Site 1168 experienced a temperate ∼ 25 °C during the early Miocene (23-17 Ma), reaching ∼ 29 °C during the mid-Miocene climatic optimum. The stepwise ∼ 10°C cooling (20-10 °C) in the mid-to-late Miocene (12.5-5.0 Ma) is larger than that observed in records from lower and higher latitudes. From the Pliocene to modern (5.3-0 Ma), STF SST first plateaus at ∼ 15°C (3 Ma), then decreases to ∼ 6 °C (1.3 Ma), and eventually increases to the modern levels around ∼ 16 °C (0 Ma), with a higher variability of 5 compared to the Miocene. Our results imply that the latitudinal temperature gradient between the Pacific Equator and the STF during late Miocene cooling increased from 4 to 14°C. Meanwhile, the SST gradient between the STF and the Antarctic margin decreased due to amplified STF cooling compared to the Antarctic margin. This implies a narrowing SST gradient in the Neogene, with contraction of warm SSTs and northward expansion of subpolar conditions.
- Published
- 2023
19. Supplementary material to "Late Cenozoic Sea Surface Temperature evolution of the South Atlantic Ocean"
- Author
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Hoem, Frida S., primary, López-Quirós, Adrián, additional, van de Lagemaat, Suzanna, additional, Etourneau, Johan, additional, Sicre, Marie-Alexandrine, additional, Escutia, Carlota, additional, Brinkhuis, Henk, additional, Peterse, Francien, additional, Sangiorgi, Francesca, additional, and Bijl, Peter K., additional
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- 2023
- Full Text
- View/download PDF
20. Stepwise mid-Cenozoic breakdown of sub-polar gyres and strengthening of the Antarctic Circumpolar Current
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Hoem, Frida S., primary, Sauermilch, Isabel, additional, van de Lagemaat, Suzanna, additional, Aleksinski, Adam K., additional, Huber, Matthew, additional, López-Quirós, Adrián, additional, van den Broek, Karlijn, additional, Etourneau, Johan, additional, Bohaty, Steve M., additional, Peterse, Francien, additional, Brinkhuis, Henk, additional, Sangiorgi, Francesca, additional, and Bijl, Peter K., additional
- Published
- 2023
- Full Text
- View/download PDF
21. Deoxygenation and organic carbon sequestration in the Tethyan realm associated with the middle Eocene climatic optimum
- Author
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Cramwinckel, Margot J., van der Ploeg, Robin, van Helmond, Niels A.G.M., Waarlo, Niels, Agnini, Claudia, Bijl, Peter K., van der Boon, Annique, Brinkhuis, Henk, Frieling, Joost, Krijgsman, Wout, Mather, Tamsin A., Middelburg, Jack J., Peterse, Francien, Slomp, Caroline P., Sluijs, Appy, Marine Palynology, Stratigraphy and paleontology, Marine palynology and palaeoceanography, Geochemistry, Paleomagnetism, Organic geochemistry, Marine Palynology, Stratigraphy and paleontology, Marine palynology and palaeoceanography, Geochemistry, Paleomagnetism, and Organic geochemistry
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Atmospheric mercury ,Dinoflagellate cysts ,Glycerol ether lipids ,Thermal maximum ,Proxy data ,Southwest pacific ,Water-column ,Geology ,Biomarker paleothermometry ,Bacterial gmgts ,North caucasus - Abstract
The middle Eocene climatic optimum (ca. 40 Ma) stands out as a transient global warming phase of ∼400 k.y. duration that interrupted long-termEocene cooling; it has been associated with a rise in atmospheric CO 2 concentrations that has been linked to a flare-up in Arabia-Eurasia continental arc volcanism. Increased organic carbon burial in the Tethys Ocean has been proposed as a carbon sequestration mechanism to bring the middle Eocene climatic optimum to an end. To further test these hypotheses, we assessed the sedimentary and geochemical expression of the middle Eocene climatic optimum in the northern Peri-Tethys, specifically, the organic-rich Kuma Formation of the Belaya River section, located on the edge of the Scythian Platform in the North Caucasus, Russia. We constructed an age-depth model using nannofossil chronobiostratigraphy. Throughout the studied middle Eocene interval (41.2−39.9 Ma), we documented sea-surface temperatures of 32−36 °C based on the tetraether index of tetraethers consisting of 86 carbons (TEX86), depending on proxy calibration, and during the early middle Eocene climatic optimum, we observed sea-surface warming of 2−3 °C. Despite the proximity of the section to the Arabia-Eurasia volcanic arc, the hypothesized source of volcanic CO2, we found no evidence for enhanced regional volcanism in sedimentary mercury concentrations. Sedimentary trace-element concentrations and iron speciation indicate reducing bottom waters throughout the middle Eocene, but the most reducing, even euxinic, conditions were reached during late middle Eocene climatic optimum cooling. This apparent regional decoupling between ocean warming and deoxygenation hints at a role for regional tectonics in causing basin restriction and anoxia. Associated excess organic carbon burial, extrapolated to the entire regional Kuma Formation, may have been ∼8.1 Tg C yr−1, comprising ∼450 Pg C over this ∼55 k.y. interval. Combined with evidence for enhanced organic carbon drawdown in the western Peri-Tethys, this supports a quantitatively significant role for the basin in the termination of the middle Eocene climatic optimum by acting as a large organic carbon sink, and these results collectively illustrate that the closing Tethys Ocean might have affected global Paleogene climate. Moreover, this study highlights the importance of the interplay between global climate and regional oceanic gateway evolution in determining local climate and oceanographic change.
- Published
- 2023
22. Polar amplification of orbital-scale climate variability in the early Eocene greenhouse world.
- Author
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Fokkema, Chris D., Agterhuis, Tobias, Gerritsma, Danielle, de Goeij, Myrthe, Xiaoqing Liu, de Regt, Pauline, Rice, Addison, Vennema, Laurens, Agnini, Claudia, Bijl, Peter K., Frieling, Joost, Huber, Matthew, Peterse, Francien, and Sluijs, Appy
- Abstract
Climate variability is typically amplified towards polar regions. The underlying causes, notably albedo and humidity changes, are challenging to accurately quantify with observations or models, hampering projections of future polar amplification. Polar amplification reconstructions from the ice-free early Eocene (~56-48 million years ago) can exclude ice albedo effects, but the required tropical temperature records for resolving timescales shorter than multi-million years are lacking. Here, we reconstruct early Eocene tropical sea surface temperature variability by presenting an up to ~4 kyr-resolution biomarker-based temperature record from Ocean Drilling Program Site 959, located in the tropical Atlantic Ocean. This record shows warming across multiple orbitally paced carbon cycle perturbations, coeval with high-latitude-derived deep-ocean bottom waters, showing that these events represent transient global warming events (hyperthermals). This implies that orbital forcing caused global temperature variability through carbon cycle feedbacks. Importantly, deep-ocean temperature variability was amplified by a factor 1.7-2.3 compared to the tropical surface ocean, corroborating available long-term estimates. This implies that fast atmospheric feedback processes controlled meridional temperature gradients on multi-million year, as well as orbital timescales during the early Eocene. Our combined records have several other implications. First, our amplification factor is somewhat larger than the same metric in fully-coupled simulations of the early Eocene (1.1-1.3), suggesting that models slightly underestimate the non-ice related -- notably hydrological -- feedbacks that cause polar amplification of climate change. Second, even outside the hyperthermals, we find synchronous eccentricity-forced temperature variability in the tropics and deep ocean that represent global mean sea surface temperature variability of up to 0.7 °C, and requires significant variability in atmospheric pCO2. We hypothesize that the responsible carbon cycle feedbacks that are independent of ice, snow and frost-related processes might play an important role in Phanerozoic orbital-scale climate variability throughout geological time, including Pleistocene glacial-interglacial climate variability. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
23. Palsys.org: an open-access taxonomic and stratigraphic database of organic-walled dinoflagellate cysts.
- Author
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Bijl, Peter K. and Brinkhuis, Henk
- Subjects
DINOFLAGELLATE cysts ,DATABASES ,IMAGE databases ,QUALITY control ,MICROPALEONTOLOGY - Abstract
It is with great pleasure that we introduce palsys.org (https://palsys.org/genus/ , last access: 8 December 2023), a fully open-access taxonomic, stratigraphic and image database of organic-walled dinoflagellate cysts. Palsys.org started as the in-house database of the Laboratory of Palaeobotany and Palynology (LPP) Foundation over 30 years ago. It is now owned by Utrecht University and has been expanded and transformed into a public online platform for use in research and education. Palsys.org includes the taxonomic descriptions of genera and species of organic walled dinoflagellate cysts, from the (often translated) literature, and emendations and synonymy, mainly following Williams et al. (2017) and the stratigraphic calibrations from DINOSTRAT (Bijl, 2022), and has around 25 000 images of species. Here, in this launch paper, we explain the history of the database, present its current functionalities and explain our set-up of the data quality control. We call upon the community to help us keep palsys.org up to date and complete by, for example, by sending additional information, imagery and feedback in general through the platform. Palsys.org brings dinoflagellate micropaleontology in line with the open-science principles of modern academia. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
24. Supplementary material to "Lipid biomarker-based sea (sub)surface temperature record offshore Tasmania over the last 23 million years"
- Author
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Hou, Suning, primary, Lamprou, Foteini, additional, Hoem, Frida S., additional, Hadju, Mohammad Rizky Nanda, additional, Sangiorgi, Francesca, additional, Peterse, Francien, additional, and Bijl, Peter K., additional
- Published
- 2022
- Full Text
- View/download PDF
25. Lipid biomarker-based sea (sub)surface temperature record offshore Tasmania over the last 23 million years
- Author
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Hou, Suning, primary, Lamprou, Foteini, additional, Hoem, Frida S., additional, Hadju, Mohammad Rizky Nanda, additional, Sangiorgi, Francesca, additional, Peterse, Francien, additional, and Bijl, Peter K., additional
- Published
- 2022
- Full Text
- View/download PDF
26. Maastrichtian–Rupelian paleoclimates in the southwest Pacific – a critical re-evaluation of biomarker paleothermometry and dinoflagellate cyst paleoecology at Ocean Drilling Program Site 1172
- Author
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Bijl, Peter K., Frieling, Joost, Cramwinckel, Margot J., Boschman, Christine, Sluijs, Appy, Peterse, Francien, Marine palynology and palaeoceanography, Stratigraphy and paleontology, Organic geochemistry, and Marine Palynology
- Subjects
geography ,Global and Planetary Change ,Plateau ,geography.geographical_feature_category ,Stratigraphy ,Palaeontology ,Holocene climatic optimum ,Paleontology ,Subsidence (atmosphere) ,Environmental protection ,Environmental pollution ,Sedimentary depositional environment ,Environmental sciences ,Sea surface temperature ,Oceanography ,TD172-193.5 ,TD169-171.8 ,Paleoecology ,Dinocyst ,Sedimentary rock ,GE1-350 ,Geology - Abstract
Sea surface temperature (SST) reconstructions based on isoprenoid glycerol dialkyl glycerol tetraether (isoGDGT) distributions from the Eocene southwest (SW) Pacific Ocean are unequivocally warmer than can be reconciled with state-of-the-art fully coupled climate models. However, the SST signal preserved in sedimentary archives can be affected by contributions of additional isoGDGT sources. Methods now exist to identify and possibly correct for overprinting effects on the isoGDGT distribution in marine sediments. Here, we use the current proxy insights to (re-)assess the reliability of the isoGDGT-based SST signal in 69 newly analyzed and 242 reanalyzed sediments at Ocean Drilling Program (ODP) Site 1172 (East Tasman Plateau, Australia) following state-of-the-art chromatographic techniques. We compare our results with paleoenvironmental and paleoclimatologic reconstructions based on dinoflagellate cysts. The resulting ∼ 130 kyr resolution Maastrichtian–Oligocene SST record based on the TetraEther indeX of tetraethers with 86 carbon atoms (TEX86) confirms previous conclusions of anomalous warmth in the early Eocene SW Pacific and remarkably cool conditions during the mid-Paleocene. Dinocyst diversity and assemblages show a strong response to the local SST evolution, supporting the robustness of the TEX86 record. Soil-derived branched GDGTs stored in the same sediments are used to reconstruct mean annual air temperature (MAAT) of the nearby land using the Methylation index of Branched Tetraethers with 5-methyl bonds (MBT'5me) proxy. MAAT is consistently lower than SST during the early Eocene, independent of the calibration chosen. General trends in SST and MAAT are similar, except for (1) an enigmatic absence of MAAT rise during the Paleocene–Eocene Thermal Maximum and Middle Eocene Climatic Optimum, and (2) a subdued middle–late Eocene MAAT cooling relative to SST. Both dinocysts and GDGT signals suggest a mid-shelf depositional environment with strong river runoff during the Paleocene–early Eocene progressively becoming more marine thereafter. This trend reflects gradual subsidence and more pronounced wet/dry seasons in the northward-drifting Australian hinterland, which may also explain the subdued middle Eocene MAAT cooling relative to that of SST. The overall correlation between dinocyst assemblages, marine biodiversity and SST changes suggests that temperature exerted a strong influence on the surface-water ecosystem. Finally, we find support for a potential temperature control on compositional changes of branched glycerol monoalkyl glycerol tetraethers (brGMGTs) in marine sediments. It is encouraging that a critical evaluation of the GDGT signals confirms that most of the generated data are reliable. However, this also implies that the high TEX86-based SSTs for the Eocene SW Pacific and the systematic offset between absolute TEX86-based SST and MBT'5me-based MAAT estimates remain without definitive explanation.
- Published
- 2021
27. Deoxygenation and organic carbon sequestration in the Tethyan realm associated with the middle Eocene climatic optimum
- Author
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Cramwinckel, Margot J., primary, van der Ploeg, Robin, additional, van Helmond, Niels A.G.M., additional, Waarlo, Niels, additional, Agnini, Claudia, additional, Bijl, Peter K., additional, van der Boon, Annique, additional, Brinkhuis, Henk, additional, Frieling, Joost, additional, Krijgsman, Wout, additional, Mather, Tamsin A., additional, Middelburg, Jack J., additional, Peterse, Francien, additional, Slomp, Caroline P., additional, and Sluijs, Appy, additional
- Published
- 2022
- Full Text
- View/download PDF
28. Improved Model‐Data Agreement With Strongly Eddying Ocean Simulations in the Middle‐Late Eocene
- Author
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Nooteboom, Peter D., primary, Baatsen, Michiel, additional, Bijl, Peter K., additional, Kliphuis, Michael A., additional, van Sebille, Erik, additional, Sluijs, Appy, additional, Dijkstra, Henk A., additional, and von der Heydt, Anna S., additional
- Published
- 2022
- Full Text
- View/download PDF
29. Eocene to Oligocene vegetation and climate in the Tasmanian Gateway region were controlled by changes in ocean currents and pCO2
- Author
-
Amoo, Michael, Salzmann, Ulrich, Pound, Matthew J., Thompson, Nick, Bijl, Peter K., Marine palynology and palaeoceanography, and Marine Palynology
- Subjects
Global and Planetary Change ,Stratigraphy ,Palaeontology - Abstract
Considered one of the most significant climate reorganizations of the Cenozoic period, the Eocene-Oligocene Transition (EOT; ca. 34.44-33.65) is characterized by global cooling and the first major glacial advance on Antarctica. In the southern high latitudes, the EOT cooling is primarily recorded in the marine realm, and its extent and effect on the terrestrial climate and vegetation are poorly documented. Here, we present new, well-dated, continuous, high-resolution palynological (sporomorph) data and quantitative sporomorph-based climate estimates recovered from the East Tasman Plateau (ODP Site 1172) to reconstruct climate and vegetation dynamics from the late Eocene (37.97gMa) to the early Oligocene (33.06gMa). Our results indicate three major climate transitions and four vegetation communities occupying Tasmania under different precipitation and temperature regimes: (i) a warm-temperate Nothofagus-Podocarpaceae-dominated rainforest with paratropical elements from 37.97 to 37.52gMa; (ii) a cool-temperate Nothofagus-dominated rainforest with secondary Podocarpaceae rapidly expanding and taking over regions previously occupied by the warmer taxa between 37.306 and 35.60gMa; (iii) fluctuation between warm-temperate-paratropical taxa and cool temperate forest from 35.50 to 34.49gMa, followed by a cool phase across the EOT (34.30-33.82gMa); and (iv) a post-EOT (earliest Oligocene) recovery characterized by a warm-temperate forest association from 33.55 to 33.06gMa. Coincident with changes in the stratification of water masses and sequestration of carbon from surface water in the Southern Ocean, our sporomorph-based temperature estimates between 37.52 and 35.60gMa (phase ii) showed 2-3gg C terrestrial cooling. The unusual fluctuation between warm and cold temperate forest between 35.50 to 34.59gMa is suggested to be linked to the initial deepening of the Tasmanian Gateway, allowing eastern Tasmania to come under the influence of warm water associated with the proto-Leeuwin Current (PLC). Further to the above, our terrestrial data show the mean annual temperature declining by about 2gg C across the EOT before recovering in the earliest Oligocene. This phenomenon is synchronous with regional and global cooling during the EOT and linked to declining pCO2. However, the earliest Oligocene climate rebound along eastern Tasmania is linked to a transient recovery of atmospheric pCO2 and sustained deepening of the Tasmanian Gateway, promoting PLC throughflow. The three main climate transitional events across the studied interval (late Eocene-earliest Oligocene) in the Tasmanian Gateway region suggest that changes in ocean circulation due to accelerated deepening of the Tasmanian Gateway may not have been solely responsible for the changes in terrestrial climate and vegetation dynamics; a series of regional and global events, including a change in the stratification of water masses, sequestration of carbon from surface waters, and changes in pCO2, may have also played vital roles.
- Published
- 2022
30. Enhanced Terrestrial Carbon Export From East Antarctica During the Early Eocene
- Author
-
Inglis, Gordon N., Toney, Jaime L., Zhu, Jiang, Poulsen, Christopher J., Röhl, Ursula, Jamieson, Stewart S.R., Pross, Jörg, Cramwinckel, Margot J., Krishnan, Srinath, Pagani, Mark, Bijl, Peter K., Bendle, James, Marine palynology and palaeoceanography, Marine Palynology, Marine palynology and palaeoceanography, and Marine Palynology
- Subjects
lipids ,Atmospheric Science ,Palaeontology ,greenhouse ,Paleontology ,biomarkers ,DeepMIP ,leaf wax ,Oceanography ,cenozoic - Abstract
Terrestrial organic carbon (TerrOC) acts as an important CO2 sink when transported via rivers to the ocean and sequestered in coastal marine sediments. This mechanism might help to modulate atmospheric CO2 levels over short- and long timescales (103 to 106 years), but its importance during past warm climates remains unknown. Here we use terrestrial biomarkers preserved in coastal marine sediment samples from Wilkes Land, East Antarctica (~67°S) to quantify TerrOC burial during the early Eocene (~54.4 to 51.5 Ma). Terrestrial biomarker distributions indicate the delivery of plant-, soil- and peat-derived organic carbon (OC) into the marine realm. Mass accumulation rates of plant- (long-chain n-alkane) and soil-derived (hopane) biomarkers dramatically increase between the earliest Eocene (~54 Ma) and the early Eocene Climatic Optimum (EECO; ~53 Ma). This coincides with increased OC mass accumulation rates and indicates enhanced TerrOC burial during the EECO. Leaf wax δ 2H values indicate that the EECO was characterised by wetter conditions relative to the earliest Eocene, suggesting that hydroclimate exerts a first-order control on TerrOC export. Our results indicate that TerrOC burial in coastal marine sediments UOB Open could have acted as an important negative feedback mechanism during the early Eocene, but also during other warm climate intervals.
- Published
- 2022
31. Expedition 392 Preliminary Report Agulhas Plateau Cretaceous Climate: drilling the Agulhas Plateau and Transkei Basin to reconstruct the Cretaceous–Paleogene tectonic and climatic evolution of the Southern Ocean basin, 5 February–7 April 2022
- Author
-
Uenzelmann-Neben, Gabriele, Bohaty, Steven M., Childress, Laurel B., Archontikis, Odysseas A., Batenburg, Sietske J., Bijl, Peter K., Burkett, Ashley M., Chanda, Pratyusha, Coenen, Jason J., Dallanave, Edoardo, Davidson, Peter C., Doiron, Kelsey E., Geldmacher, Jörg, Gürer, Derya, Haynes, Shannon J., Herrle, Jens O., Ichiyama, Yuji, Jana, Debadrita, Jones, Matthew M., Kato, Chie, Kulhanek, Denise K., Li, Juan, Liu, Jia, McManus, James, Minakov, Alexander N., Penman, Donald E., Sprain, Courtney J., Tessin, Allyson C., Wagner, Thomas, and Westerhold, Thomas
- Published
- 2022
32. Agulhas Plateau Cretaceous Climate: drilling the Agulhas Plateau and Transkei Basin to reconstruct the Cretaceous–Paleogene tectonic and climatic evolution of the Southern Ocean basin
- Author
-
Uenzelmann-Neben, Gabriele, Bohaty, Steven M., Childress, Laurel B., Archontikis, Odysseas A., Batenburg, Sietske J., Bijl, Peter K., Burkett, Ashley M., Chanda, Pratyusha, Coenen, Jason J., Dallanave, Edoardo, Davidson, Peter C., Doiron, Kelsey E., Geldmacher, Jörg, Gürer, Derya, Haynes, Shannon J., Herrle, Jens O., Ichiyama, Yuji, Jana, Debadrita, Jones, Matthew M., Kato, Chie, Kulhanek, Denise K., Li, Juan, Liu, Jia, McManus, James, Yakutchik, Maryalice, Cawthra, Hayley C., Minakov, Alexander, Penman, Donald E., Sprain, Courtney J., Tessin, Allyson C., Wagner, Thomas, and Westerhold, Thomas
- Abstract
During International Ocean Discovery Program Expedition 392, three sites were drilled on the Agulhas Plateau and one site was drilled in the Transkei Basin in the Southwest Indian Ocean. This region was positioned at paleolatitudes of ~53°–61°S during the Late Cretaceous (van Hinsbergen et al., 2015) (100–66 Ma) and within the new and evolving gateway between the South Atlantic, Southern Ocean, and southern Indian Ocean basins. Recovery of basement rocks and sedimentary sequences from the Agulhas Plateau sites and a thick sedimentary sequence in the Transkei Basin provides a wealth of new data to (1) determine the nature and origin of the Agulhas Plateau; (2) significantly advance the understanding of how Cretaceous temperatures, ocean circulation, and sedimentation patterns evolved as CO2 levels rose and fell and the breakup of Gondwana progressed; (3) document long-term paleoceanographic variability through the Late Cretaceous and Paleogene; and (4) investigate geochemical interactions between igneous rocks, sediments, and pore waters through the life cycle of a large igneous province (LIP). Importantly, postcruise analysis of Expedition 392 drill cores will allow testing of competing hypotheses concerning Agulhas Plateau LIP formation and the role of deep ocean circulation changes through southern gateways in controlling Late Cretaceous–early Paleogene climate evolution.
- Published
- 2022
33. Late Cenozoic Sea Surface Temperature evolution of the South Atlantic Ocean.
- Author
-
Hoem, Frida S., López-Quirós, Adrián, van de Lagemaat, Suzanna, Etourneau, Johan, Sicre, Marie-Alexandrine, Escutia, Carlota, Brinkhuis, Henk, Peterse, Francien, Sangiorgi, Francesca, and Bijl, Peter K.
- Subjects
OCEAN temperature ,CENOZOIC Era ,ANTARCTIC Circumpolar Current ,OCEAN ,ANTARCTIC ice ,MELTWATER ,ICE shelves ,SUBGLACIAL lakes - Abstract
At present, a strong latitudinal sea surface temperature (SST) gradient of ~16 °C exists across the Southern Ocean, maintained by the Antarctic Circumpolar Current (ACC) and a set of complex frontal systems. Together with the Antarctic ice masses, this system has formed one of the most important global climate regulators. The timing of the onset of the ACC-system, its development towards modern-day strength, and the consequences for e.g., the latitudinal SST gradient around the southern Atlantic Ocean, are still uncertain. Here we present new TEX
86 -biomarker records, calibrated to SST, from two sites located east of Drake Passage (southern South Atlantic) to assist in better understanding two critical time intervals of prominent climate transitions during the Cenozoic: The Late Eocene–Early Oligocene (ODP Site 696) and Middle–Late Miocene (IODP Site U1536) transitions. Our results overall show rather temperate conditions (20–11 °C) during the Late Eocene to Early Oligocene interval, with a weaker latitudinal SST gradient (~8 °C) across the Atlantic sector of the Southern Ocean compared to present day (~16 °C). We ascribe the regional similarity in SSTs across the Late Eocene–Early Oligocene South Atlantic to a persistent, strong Subpolar Gyre circulation, connecting all sites, which can only exist in absence of a strong throughflow across the Drake Passage. Surprisingly, the southern South Atlantic records show comparable SSTs (~12–14 °C) during both the Earliest Oligocene Oxygen Isotope Step (EOIS, ~33.65 Ma) and the Miocene Climate Optimum (MCO, ~16.5 Ma). Apparently, maximum Oligocene Antarctic ice volume could coexist with warm ice-proximal surface ocean conditions, while at similar ocean temperatures, the Middle Miocene Antarctic ice sheet was strongly reduced. Southern South Atlantic SSTs cooled to ~5 °C at the onset of the Middle Miocene Climate Transition (MMCT, 14 Ma), making it the coldest oceanic region recorded around Antarctica and the likely main location for deep water formation. The already cold southern South Atlantic conditions at MMCT meant it experienced little cooling during the latter part of the Miocene, which contrasts the profound cooling due to northward expansion of the Southern Ocean frontal systems in the lower latitudes and other sectors of the Southern Ocean. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
34. Eocene to Oligocene vegetation and climate in the Tasmanian Gateway region were controlled by changes in ocean currents and <i>p</i>CO<sub>2</sub>
- Author
-
Amoo, Michael, primary, Salzmann, Ulrich, additional, Pound, Matthew J., additional, Thompson, Nick, additional, and Bijl, Peter K., additional
- Published
- 2022
- Full Text
- View/download PDF
35. Sedimentary microplankton distributions are shaped by oceanographically connected areas
- Author
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Nooteboom, Peter D., primary, Bijl, Peter K., additional, Kehl, Christian, additional, van Sebille, Erik, additional, Ziegler, Martin, additional, von der Heydt, Anna S., additional, and Dijkstra, Henk A., additional
- Published
- 2022
- Full Text
- View/download PDF
36. DINOSTRAT: a global database of the stratigraphic and paleolatitudinal distribution of Mesozoic–Cenozoic organic-walled dinoflagellate cysts
- Author
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Bijl, Peter K., primary
- Published
- 2022
- Full Text
- View/download PDF
37. Vegetation change across the Drake Passage region linked to late Eocene cooling and glacial disturbance after the Eocene–Oligocene transition
- Author
-
Thompson, Nick, primary, Salzmann, Ulrich, additional, López-Quirós, Adrián, additional, Bijl, Peter K., additional, Hoem, Frida S., additional, Etourneau, Johan, additional, Sicre, Marie-Alexandrine, additional, Roignant, Sabine, additional, Hocking, Emma, additional, Amoo, Michael, additional, and Escutia, Carlota, additional
- Published
- 2022
- Full Text
- View/download PDF
38. Enhanced Terrestrial Carbon Export From East Antarctica During the Early Eocene
- Author
-
Inglis, Gordon N., primary, Toney, Jaime L., additional, Zhu, Jiang, additional, Poulsen, Christopher J., additional, Röhl, Ursula, additional, Jamieson, Stewart S. R., additional, Pross, Jörg, additional, Cramwinckel, Margot J., additional, Krishnan, Srinath, additional, Pagani, Mark, additional, Bijl, Peter K., additional, and Bendle, James, additional
- Published
- 2022
- Full Text
- View/download PDF
39. Terrestrial Climate and Vegetation Change in the Western Tasmanian Region from the Late Eocene to Late Oligocene
- Author
-
Amoo, Michael, primary, Salzmann, Ulrich, additional, Pound, Matthew J., additional, Hoem, Frida S., additional, Thompson, Nick, additional, and Bijl, Peter K., additional
- Published
- 2022
- Full Text
- View/download PDF
40. Eocene to Oligocene vegetation and climate in the Tasmanian Gateway region controlled by changes in ocean currents and pCO2
- Author
-
Amoo, Michael, Salzmann, Ulrich, Pound, Matthew J., Thompson, Nick, and Bijl, Peter K.
- Subjects
F700 ,F800 - Abstract
Considered as one of the most significant climate reorganisations of the Cenozoic period, the Eocene-Oligocene Transition (EOT; ca. 34.44–33.65) is characterised by global cooling and the first major glacial advance on Antarctica. While in the southern high-latitudes, the EOT cooling is primarily recorded in the marine realm, the extent and effect on terrestrial climate and vegetation is poorly documented. Here, we present a new, well-dated, continuous, high-resolution palynological (sporomorph) data and quantitative sporomorph-based climate estimates recovered from the East Tasman Plateau (ODP Site 1172) to reconstruct climate and vegetation dynamics from the late Eocene (37.97 Ma) to early Oligocene (33.06 Ma). Our results indicate three major climate transitions and four vegetation communities occupying Tasmania under different precipitation and temperature regimes: (i) a warm-temperate Nothofagus-Podocarpaceae dominated rainforest with paratropical elements from 37.97–37.52 Ma; (ii) cool-temperate Nothofagus dominated rainforest with secondary Podocarpaceae rapidly expanding and taking over regions previously occupied by the warmer taxa between 37.306–35.60 Ma; (iii) fluctuation between warm temperate – paratropical taxa and cool temperate forest from 35.50–34.49 Ma, followed by a cool phase across the EOT (34.30–33.82 Ma); (iv) post-EOT (earliest Oligocene) recovery characterised by a warm-temperate forest association from 33.55–33.06 Ma. Coincident with changes in stratification of water masses and sequestration of carbon from surface water in the Southern Ocean, our sporomorph-based temperature estimates between 37.52 Ma and 35.60 Ma (phase ii) showed 2–3 °C terrestrial cooling. The unusual fluctuation between warm and cold temperate forest between 35.50 to 34.59 Ma is suggested to be linked to the initial deepening of the Tasmanian Gateway allowing eastern Tasmania to come under the influence of warm water associated with the proto-Leeuwin Current (PLC). Further to the above, our terrestrial data show mean annual temperature declining by about 2 °C across the EOT before recovering in the earliest Oligocene. This phenomenon is synchronous with regional and global cooling during the EOT and linked to declining pCO2. However, the earliest Oligocene climate rebound along eastern Tasmania is linked to transient recovery of atmospheric pCO2 and sustained deepening of the Tasmanian Gateway, promoting PLC throughflow. The three main climate transitional events across the studied interval (late Eocene–earliest Oligocene) in the Tasmanian Gateway region suggest that changes in ocean circulation due to accelerated deepening of the Tasmanian Gateway may not have been solely responsible for the changes in terrestrial climate and vegetation dynamics, but a series of regional and global events, including a change in stratification of water masses, sequestration of carbon from surface waters, and changes in pCO2 may have played vital roles.
- Published
- 2021
41. Late Eocene–early Miocene evolution of the southern Australian subtropical front: a marine palynological approach
- Author
-
Hoem, Frida S., primary, Sauermilch, Isabel, additional, Hou, Suning, additional, Brinkhuis, Henk, additional, Sangiorgi, Francesca, additional, and Bijl, Peter K., additional
- Published
- 2021
- Full Text
- View/download PDF
42. Eocene to Oligocene vegetation and climate in the Tasmanian Gateway region controlled by changes in ocean currents and pCO<sub>2</sub>
- Author
-
Amoo, Michael, primary, Salzmann, Ulrich, additional, Pound, Matthew J., additional, Thompson, Nick, additional, and Bijl, Peter K., additional
- Published
- 2021
- Full Text
- View/download PDF
43. Lipid biomarker-based sea (sub)surface temperature record offshore Tasmania over the last 23 million years.
- Author
-
Suning Hou, Lamprou, Foteini, Hoem, Frida S., Hadju, Mohammad Rizky Nanda, Sangiorgi, Francesca, Peterse, Francien, and Bijl, Peter K.
- Abstract
The Neogene (23.04-2.58 Ma) is characterized by progressive buildup of Antarctic and Northern Hemisphere ice volume and climate cooling. Heat/moisture delivery to Antarctica is to a large extent regulated by the strength of meridional temperature gradients. However, the evolution of the Southern Ocean frontal systems remains scarcely studied in the Neogene. Here we present the first long-term continuous sea (sub)surface temperature (SST) record of the subtropical front area in the Southern Ocean at Ocean Drilling Program (ODP) Site 1168 off western Tasmania. This site is at present located near the subtropical front (STF), as it was during the Neogene, despite a 10 degree northward tectonic drift of Tasmania during the Neogene. We analyzed glycerol dialkyl glycerol tetraethers (GDGTs, on 433 samples) and alkenones (on 163 samples) and reconstructed the paleotemperature evolution using TEX
86 and Uk '37 as two independent quantitative proxies. Both proxies indicate that Site 1168 experienced a temperate ~25°C during early Miocene (23-17 Ma), reaching ~29 °C during the mid-Miocene Climatic Optimum. The stepwise ~10°C cooling (20-10°C) in the mid-to-late Miocene (12.5-5.0 Ma) is larger than observed in records from lower and higher latitudes. From the Pliocene to modern (5.3-0 Ma), STF SST first plateaus at ~15°C (3 Ma), then decreases to ~6°C (1.3 Ma), and eventually increases to the modern levels around ~16 °C (0 Ma), with a higher variability of 5 degrees compared to the Miocene. Our results imply that the latitudinal temperature gradient between the Pacific equator and STF during late Miocene cooling increased from 4°C to 14°C. Meanwhile, the SST gradient between the STF and the Antarctic margin decreased due to amplified STF cooling compared to the Antarctic Margin. This implies a narrowing SST gradient in the Neogene, with contraction of warm SSTs and northward expansion of subpolar conditions. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
44. Eocene-Oligocene paleoenvironmental changes in the South Orkney Microcontinent (Antarctica) linked to the opening of Powell Basin
- Author
-
López-Quirós, Adrián, primary, Escutia, Carlota, additional, Etourneau, Johan, additional, Rodríguez-Tovar, Francisco J., additional, Roignant, Sabine, additional, Lobo, Francisco J., additional, Thompson, Nick, additional, Bijl, Peter K., additional, Bohoyo, Fernando, additional, Salzmann, Ulrich, additional, Evangelinos, Dimitris, additional, Salabarnada, Ariadna, additional, Hoem, Frida S., additional, and Sicre, Marie-Alexandrine, additional
- Published
- 2021
- Full Text
- View/download PDF
45. Eocene to Oligocene vegetation and climate in the Tasmanian Gateway region controlled by changes in ocean currents and 푝CO2.
- Author
-
Amoo, Michael, Salzmann, Ulrich, Pound, Matthew J., Thompson, Nick, and Bijl, Peter K.
- Abstract
Considered as one of the most significant climate reorganisations of the Cenozoic period, the Eocene-Oligocene Transition (EOT; ca. 34.44-33.65) is characterised by global cooling and the first major glacial advance on Antarctica. While in the southern high-latitudes, the EOT cooling is primarily recorded in the marine realm, the extent and effect on terrestrial climate and vegetation is poorly documented. Here, we present a new, well-dated, continuous, high-resolution palynological (sporomorph) data and quantitative sporomorph-based climate estimates recovered from the East Tasman Plateau (ODP Site 1172) to reconstruct climate and vegetation dynamics from the late Eocene (37.97 Ma) to early Oligocene (33.06 Ma). Our results indicate three major climate transitions and four vegetation communities occupying Tasmania under different precipitation and temperature regimes: (i) a warm-temperate Nothofagus-Podocarpaceae dominated rainforest with paratropical elements from 37.97-37.52 Ma; (ii) cool-temperate Nothofagus dominated rainforest with secondary Podocarpaceae rapidly expanding and taking over regions previously occupied by the warmer taxa between 37.306-35.60 Ma; (iii) fluctuation between warm temperate - paratropical taxa and cool temperate forest from 35.50-34.49 Ma, followed by a cool phase across the EOT (34.30-33.82 Ma); (iv) post-EOT (earliest Oligocene) recovery characterised by a warm-temperate forest association from 33.55-33.06 Ma. Coincident with changes in stratification of water masses and sequestration of carbon from surface water in the Southern Ocean, our sporomorph-based temperature estimates between 37.52 Ma and 35.60 Ma (phase ii) showed 2-3 ºC terrestrial cooling. The unusual fluctuation between warm and cold temperate forest between 35.50 to 34.59 Ma is suggested to be linked to the initial deepening of the Tasmanian Gateway allowing eastern Tasmania to come under the influence of warm water associated with the proto-Leeuwin Current (PLC). Further to the above, our terrestrial data show mean annual temperature declining by about 2 ºC across the EOT before recovering in the earliest Oligocene. This phenomenon is synchronous with regional and global cooling during the EOT and linked to declining 푝CO
2 . However, the earliest Oligocene climate rebound along eastern Tasmania is linked to transient recovery of atmospheric 푝CO2 and sustained deepening of the Tasmanian Gateway, promoting PLC throughflow. The three main climate transitional events across the studied interval (late Eocene-earliest Oligocene) in the Tasmanian Gateway region suggest that changes in ocean circulation due to accelerated deepening of the Tasmanian Gateway may not have been solely responsible for the changes in terrestrial climate and vegetation dynamics, but a series of regional and global events, including a change in stratification of water masses, sequestration of carbon from surface waters, and changes in 푝CO2 may have played vital roles. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
46. Toward a Cenozoic history of atmospheric CO 2 .
- Author
-
Hönisch B, Royer DL, Breecker DO, Polissar PJ, Bowen GJ, Henehan MJ, Cui Y, Steinthorsdottir M, McElwain JC, Kohn MJ, Pearson A, Phelps SR, Uno KT, Ridgwell A, Anagnostou E, Austermann J, Badger MPS, Barclay RS, Bijl PK, Chalk TB, Scotese CR, de la Vega E, DeConto RM, Dyez KA, Ferrini V, Franks PJ, Giulivi CF, Gutjahr M, Harper DT, Haynes LL, Huber M, Snell KE, Keisling BA, Konrad W, Lowenstein TK, Malinverno A, Guillermic M, Mejía LM, Milligan JN, Morton JJ, Nordt L, Whiteford R, Roth-Nebelsick A, Rugenstein JKC, Schaller MF, Sheldon ND, Sosdian S, Wilkes EB, Witkowski CR, Zhang YG, Anderson L, Beerling DJ, Bolton C, Cerling TE, Cotton JM, Da J, Ekart DD, Foster GL, Greenwood DR, Hyland EG, Jagniecki EA, Jasper JP, Kowalczyk JB, Kunzmann L, Kürschner WM, Lawrence CE, Lear CH, Martínez-Botí MA, Maxbauer DP, Montagna P, Naafs BDA, Rae JWB, Raitzsch M, Retallack GJ, Ring SJ, Seki O, Sepúlveda J, Sinha A, Tesfamichael TF, Tripati A, van der Burgh J, Yu J, Zachos JC, and Zhang L
- Abstract
The geological record encodes the relationship between climate and atmospheric carbon dioxide (CO
2 ) over long and short timescales, as well as potential drivers of evolutionary transitions. However, reconstructing CO2 beyond direct measurements requires the use of paleoproxies and herein lies the challenge, as proxies differ in their assumptions, degree of understanding, and even reconstructed values. In this study, we critically evaluated, categorized, and integrated available proxies to create a high-fidelity and transparently constructed atmospheric CO2 record spanning the past 66 million years. This newly constructed record provides clearer evidence for higher Earth system sensitivity in the past and for the role of CO2 thresholds in biological and cryosphere evolution.- Published
- 2023
- Full Text
- View/download PDF
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