1
|
Dutkiewicz A, Boulila S, Dietmar Müller R. Deep-sea hiatus record reveals orbital pacing by 2.4 Myr eccentricity grand cycles. Nat Commun 2024; 15:1998. [PMID: 38472187 PMCID: PMC10933315 DOI: 10.1038/s41467-024-46171-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 02/15/2024] [Indexed: 03/14/2024] Open
Abstract
Astronomical forcing of Earth's climate is embedded in the rhythms of stratigraphic records, most famously as short-period (104-105 year) Milankovitch cycles. Astronomical grand cycles with periods of millions of years also modulate climate variability but have been detected in relatively few proxy records. Here, we apply spectral analysis to a dataset of Cenozoic deep-sea hiatuses to reveal a ~2.4 Myr eccentricity signal, disrupted by episodes of major tectonic forcing. We propose that maxima in the hiatus cycles correspond to orbitally-forced intensification of deep-water circulation and erosive bottom current activity, linked to eccentricity maxima and peaks in insolation and seasonality. A prominent episode of cyclicity disturbance coincides with the Paleocene-Eocene Thermal Maximum (PETM) at ~56 Myr ago, and correlates with a chaotic orbital transition in the Solar System evident in several astronomical solutions. This hints at a potential intriguing coupling between the PETM and Solar System chaos.
Collapse
Affiliation(s)
- Adriana Dutkiewicz
- EarthByte Group, School of Geosciences, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Slah Boulila
- Sorbonne Université, CNRS, Institut des Sciences de la Terre Paris, ISTeP, 75005, Paris, France
- ASD/IMCCE, CNRS‑UMR8028, Observatoire de Paris, PSL University, Sorbonne Université, 75014, Paris, France
| | - R Dietmar Müller
- EarthByte Group, School of Geosciences, The University of Sydney, Sydney, NSW, 2006, Australia
| |
Collapse
|
2
|
Jamieson SSR, Ross N, Paxman GJG, Clubb FJ, Young DA, Yan S, Greenbaum J, Blankenship DD, Siegert MJ. An ancient river landscape preserved beneath the East Antarctic Ice Sheet. Nat Commun 2023; 14:6507. [PMID: 37875503 PMCID: PMC10597991 DOI: 10.1038/s41467-023-42152-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 10/02/2023] [Indexed: 10/26/2023] Open
Abstract
The East Antarctic Ice Sheet (EAIS) has its origins ca. 34 million years ago. Since then, the impact of climate change and past fluctuations in the EAIS margin has been reflected in periods of extensive vs. restricted ice cover and the modification of much of the Antarctic landscape. Resolving processes of landscape evolution is therefore critical for establishing ice sheet history, but it is rare to find unmodified landscapes that record past ice conditions. Here, we discover an extensive relic pre-glacial landscape preserved beneath the central EAIS despite millions of years of ice cover. The landscape was formed by rivers prior to ice sheet build-up but later modified by local glaciation before being dissected by outlet glaciers at the margin of a restricted ice sheet. Preservation of the relic surfaces indicates an absence of significant warm-based ice throughout their history, suggesting any transitions between restricted and expanded ice were rapid.
Collapse
Affiliation(s)
| | - Neil Ross
- School of Geography, Politics and Sociology, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Guy J G Paxman
- Department of Geography, Durham University, Durham, DH1 3LE, UK
| | - Fiona J Clubb
- Department of Geography, Durham University, Durham, DH1 3LE, UK
| | - Duncan A Young
- University of Texas Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, USA
| | - Shuai Yan
- University of Texas Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, USA
- Department of Geosciences, Jackson School of Geosciences, University of Texas at Austin, Austin, USA
| | - Jamin Greenbaum
- Scripps Institute for Oceanography, University of California at San Diego, San Diego, USA
| | - Donald D Blankenship
- University of Texas Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, USA
| | - Martin J Siegert
- Tremough House, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK
| |
Collapse
|
3
|
Hochmuth K, Whittaker JM, Sauermilch I, Klocker A, Gohl K, LaCasce JH. Southern Ocean biogenic blooms freezing-in Oligocene colder climates. Nat Commun 2022; 13:6785. [PMID: 36351905 PMCID: PMC9646741 DOI: 10.1038/s41467-022-34623-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 11/01/2022] [Indexed: 11/10/2022] Open
Abstract
Crossing a key atmospheric CO2 threshold triggered a fundamental global climate reorganisation ~34 million years ago (Ma) establishing permanent Antarctic ice sheets. Curiously, a more dramatic CO2 decline (~800-400 ppm by the Early Oligocene(~27 Ma)), postdates initial ice sheet expansion but the mechanisms driving this later, rapid drop in atmospheric carbon during the early Oligocene remains elusive and controversial. Here we use marine seismic reflection and borehole data to reveal an unprecedented accumulation of early Oligocene strata (up to 2.2 km thick over 1500 × 500 km) with a major biogenic component in the Australian Southern Ocean. High-resolution ocean simulations demonstrate that a tectonically-driven, one-off reorganisation of ocean currents, caused a unique period where current instability coincided with high nutrient input from the Antarctic continent. This unrepeated and short-lived environment favoured extreme bioproductivity and enhanced sediment burial. The size and rapid accumulation of this sediment package potentially holds ~1.067 × 1015 kg of the 'missing carbon' sequestered during the decline from an Eocene high CO2-world to a mid-Oligocene medium CO2-world, highlighting the exceptional role of the Southern Ocean in modulating long-term climate.
Collapse
Affiliation(s)
- Katharina Hochmuth
- grid.9918.90000 0004 1936 8411School of Geography, Geology and the Environment, University of Leicester, Leicester, UK ,grid.1009.80000 0004 1936 826XInstitute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS Australia ,grid.1009.80000 0004 1936 826XAustralian Center for Excellence in Antarctic Sciences, University of Tasmania, Hobart, TAS Australia
| | - Joanne M. Whittaker
- grid.1009.80000 0004 1936 826XInstitute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS Australia ,grid.1009.80000 0004 1936 826XAustralian Center for Excellence in Antarctic Sciences, University of Tasmania, Hobart, TAS Australia
| | - Isabel Sauermilch
- grid.5477.10000000120346234Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands
| | - Andreas Klocker
- grid.5510.10000 0004 1936 8921Department of Geosciences, University of Oslo, Oslo, Norway ,Present Address: NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway
| | - Karsten Gohl
- grid.10894.340000 0001 1033 7684Alfred Wegener Institute Helmholtz-Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Joseph H. LaCasce
- grid.5510.10000 0004 1936 8921Department of Geosciences, University of Oslo, Oslo, Norway
| |
Collapse
|
4
|
Marcussen T, Ballard HE, Danihelka J, Flores AR, Nicola MV, Watson JM. A Revised Phylogenetic Classification for Viola (Violaceae). PLANTS 2022; 11:plants11172224. [PMID: 36079606 PMCID: PMC9460890 DOI: 10.3390/plants11172224] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 08/15/2022] [Accepted: 08/16/2022] [Indexed: 11/26/2022]
Abstract
The genus Viola (Violaceae) is among the 40–50 largest genera among angiosperms, yet its taxonomy has not been revised for nearly a century. In the most recent revision, by Wilhelm Becker in 1925, the then-known 400 species were distributed among 14 sections and numerous unranked groups. Here, we provide an updated, comprehensive classification of the genus, based on data from phylogeny, morphology, chromosome counts, and ploidy, and based on modern principles of monophyly. The revision is presented as an annotated global checklist of accepted species of Viola, an updated multigene phylogenetic network and an ITS phylogeny with denser taxon sampling, a brief summary of the taxonomic changes from Becker’s classification and their justification, a morphological binary key to the accepted subgenera, sections and subsections, and an account of each infrageneric subdivision with justifications for delimitation and rank including a description, a list of apomorphies, molecular phylogenies where possible or relevant, a distribution map, and a list of included species. We distribute the 664 species accepted by us into 2 subgenera, 31 sections, and 20 subsections. We erect one new subgenus of Viola (subg. Neoandinium, a replacement name for the illegitimate subg. Andinium), six new sections (sect. Abyssinium, sect. Himalayum, sect. Melvio, sect. Nematocaulon, sect. Spathulidium, sect. Xanthidium), and seven new subsections (subsect. Australasiaticae, subsect. Bulbosae, subsect. Clausenianae, subsect. Cleistogamae, subsect. Dispares, subsect. Formosanae, subsect. Pseudorupestres). Evolution within the genus is discussed in light of biogeography, the fossil record, morphology, and particular traits. Viola is among very few temperate and widespread genera that originated in South America. The biggest identified knowledge gaps for Viola concern the South American taxa, for which basic knowledge from phylogeny, chromosome counts, and fossil data is virtually absent. Viola has also never been subject to comprehensive anatomical study. Studies into seed anatomy and morphology are required to understand the fossil record of the genus.
Collapse
Affiliation(s)
- Thomas Marcussen
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis (CEES), University of Oslo, P.O. Box 1066 Blindern, NO-0316 Oslo, Norway
- Correspondence:
| | - Harvey E. Ballard
- Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701, USA
| | - Jiří Danihelka
- Department of Botany and Zoology, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic
- Czech Academy of Sciences, Institute of Botany, Zámek 1, CZ-252 43 Průhonice, Czech Republic
| | - Ana R. Flores
- Independent Researcher, Casilla 161, Los Andes 2100412, Chile
| | - Marcela V. Nicola
- Instituto de Botánica Darwinion (IBODA, CONICET-ANCEFN), Labardén 200, Casilla de Correo 22, San Isidro, Buenos Aires B1642HYD, Argentina
| | - John M. Watson
- Independent Researcher, Casilla 161, Los Andes 2100412, Chile
| |
Collapse
|
5
|
Nooteboom PD, Baatsen M, Bijl PK, Kliphuis MA, van Sebille E, Sluijs A, Dijkstra HA, von der Heydt AS. Improved Model-Data Agreement With Strongly Eddying Ocean Simulations in the Middle-Late Eocene. PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY 2022; 37:e2021PA004405. [PMID: 36248180 PMCID: PMC9540656 DOI: 10.1029/2021pa004405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 07/21/2022] [Accepted: 07/21/2022] [Indexed: 06/16/2023]
Abstract
Model simulations of past climates are increasingly found to compare well with proxy data at a global scale, but regional discrepancies remain. A persistent issue in modeling past greenhouse climates has been the temperature difference between equatorial and (sub-)polar regions, which is typically much larger in simulations than proxy data suggest. Particularly in the Eocene, multiple temperature proxies suggest extreme warmth in the southwest Pacific Ocean, where model simulations consistently suggest temperate conditions. Here, we present new global ocean model simulations at 0.1° horizontal resolution for the middle-late Eocene. The eddies in the high-resolution model affect poleward heat transport and local time-mean flow in critical regions compared to the noneddying flow in the standard low-resolution simulations. As a result, the high-resolution simulations produce higher surface temperatures near Antarctica and lower surface temperatures near the equator compared to the low-resolution simulations, leading to better correspondence with proxy reconstructions. Crucially, the high-resolution simulations are also much more consistent with biogeographic patterns in endemic-Antarctic and low-latitude-derived plankton, and thus resolve the long-standing discrepancy of warm subpolar ocean temperatures and isolating polar gyre circulation. The results imply that strongly eddying model simulations are required to reconcile discrepancies between regional proxy data and models, and demonstrate the importance of accurate regional paleobathymetry for proxy-model comparisons.
Collapse
Affiliation(s)
- Peter D. Nooteboom
- Department of PhysicsInstitute for Marine and Atmospheric Research Utrecht (IMAU)Utrecht UniversityUtrechtThe Netherlands
- Centre for Complex Systems StudiesUtrecht UniversityUtrechtThe Netherlands
| | - Michiel Baatsen
- Department of PhysicsInstitute for Marine and Atmospheric Research Utrecht (IMAU)Utrecht UniversityUtrechtThe Netherlands
| | - Peter K. Bijl
- Department of Earth SciencesUtrecht UniversityUtrechtThe Netherlands
| | - Michael A. Kliphuis
- Department of PhysicsInstitute for Marine and Atmospheric Research Utrecht (IMAU)Utrecht UniversityUtrechtThe Netherlands
| | - Erik van Sebille
- Department of PhysicsInstitute for Marine and Atmospheric Research Utrecht (IMAU)Utrecht UniversityUtrechtThe Netherlands
- Centre for Complex Systems StudiesUtrecht UniversityUtrechtThe Netherlands
| | - Appy Sluijs
- Department of Earth SciencesUtrecht UniversityUtrechtThe Netherlands
| | - Henk A. Dijkstra
- Department of PhysicsInstitute for Marine and Atmospheric Research Utrecht (IMAU)Utrecht UniversityUtrechtThe Netherlands
- Centre for Complex Systems StudiesUtrecht UniversityUtrechtThe Netherlands
| | - Anna S. von der Heydt
- Department of PhysicsInstitute for Marine and Atmospheric Research Utrecht (IMAU)Utrecht UniversityUtrechtThe Netherlands
- Centre for Complex Systems StudiesUtrecht UniversityUtrechtThe Netherlands
| |
Collapse
|
6
|
Climate transition at the Eocene-Oligocene influenced by bathymetric changes to the Atlantic-Arctic oceanic gateways. Proc Natl Acad Sci U S A 2022; 119:e2115346119. [PMID: 35446685 PMCID: PMC9169914 DOI: 10.1073/pnas.2115346119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
The results show that dynamic variations in the Earth’s interior could have played a key role in the Eocene–Oligocene climatic transition (∼33.9 Ma) and the inception of glaciations. Pulsations in the Iceland mantle plume modified the bathymetry of the Greenland–Scotland Ridge, which affected deep water formation in the North Atlantic. Our model simulations show that the changes in the Atlantic–Arctic oceanic gateways cooled the Southern Hemisphere, and later the Northern Hemisphere, paving the way for the growth of major land-based ice sheets. This supplements the current view that decreasing atmospheric CO2 concentrations and/or changes to the Southern Ocean gateways or the Tethys Seaway dominated climate changes and the inception of glaciations at the time. The Eocene–Oligocene Transition (∼33.9 Ma) marks the largest step transformation within the Cenozoic cooling trend and is characterized by a sudden growth of the Antarctic ice sheets, cooling of the interior ocean, and the establishment of strong meridional temperature gradients. Here we examine the climatic impact of oceanic gateway changes at the Eocene–Oligocene Transition by implementing detailed paleogeographic reconstructions with realistic paleobathymetric models for the Atlantic–Arctic basins in a state-of-the-art earth system model (the Norwegian Earth System Model [NorESM-F]). We demonstrate that the warm Eocene climate is highly sensitive to depth variations of the Greenland–Scotland Ridge and the proto–Fram Strait as they control the freshwater leakage from the Arctic to the North Atlantic. Our results, and proxy evidence, suggest that changes in these gateways controlled the ocean circulation and played a critical role in the growth of land-based ice sheets, alongside CO2-driven global cooling. Specifically, we suggest that a shallow connection between the Arctic and North Atlantic restricted the southward flow of fresh surface waters during the Late Eocene allowing for a North Atlantic overturning circulation. Consequently, the Southern Hemisphere cooled by several degrees paving the way for the glaciation of Antarctica. Shortly after, the connection to the Arctic deepened due to weakening dynamic support from the Iceland Mantle Plume. This weakened the North Atlantic overturning and cooled the Northern Hemisphere, thereby promoting glaciations there. Our study points to a controlling role of the Northeast Atlantic gateways and decreasing atmospheric CO2 in the onset of glaciations in both hemispheres.
Collapse
|