Global Mean and Relative Sea-Level Changes Over the Past 66 Myr: Implications for Early Eocene Ice Sheets
We estimate ice-volume driven (barystatic; BSL) sea-level changes for the Cenozoic using new Mg/Ca data from 58 to 48 Ma and a revised analysis of Mg/Ca trends over the past 66 Myr. We combine records of BSL, temperature-driven sea level, and long-term ocean basin volume variations to derive a new g...
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Frontiers Media S.A.
2024-12-01
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| Series: | Earth Science, Systems and Society |
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| Online Access: | https://www.lyellcollection.org/doi/10.3389/esss.2023.10091 |
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| author | K. G. Miller W. J. Schmelz J. V. Browning Y. Rosenthal A. V. Hess R. E. Kopp J. D. Wright |
| author_facet | K. G. Miller W. J. Schmelz J. V. Browning Y. Rosenthal A. V. Hess R. E. Kopp J. D. Wright |
| author_sort | K. G. Miller |
| collection | DOAJ |
| description | We estimate ice-volume driven (barystatic; BSL) sea-level changes for the Cenozoic using new Mg/Ca data from 58 to 48 Ma and a revised analysis of Mg/Ca trends over the past 66 Myr. We combine records of BSL, temperature-driven sea level, and long-term ocean basin volume variations to derive a new global mean geocentric sea level (GMGSL; “eustatic”) estimate. Bayesian analysis with Gaussian process priors shows that our BSL estimate shares a component that covaries on the Myr scale with “backstripped” relative sea-level (RSL) estimates (accounting for compaction, loading, and thermal subsidence) from the US Mid-Atlantic Coastal Plain, validating our method and estimates with errors of ±10 m. Peak warmth, elevated GMGSL and BSL, high CO2, and ice-free conditions occurred at times in the Paleocene to Eocene (ca. 64, 57.5, 35 Ma) and in much of the Early Eocene (55–48 Ma). However, our new results show that the Early Eocene was punctuated at specific times by several Myr-scale sea level lowerings (∼20–40 m) that require growth and decay of significant continental ice sheets even in the supposedly “ice-free” world. Continental-scale ice sheets waxed and waned beginning ca. 34 Ma (>50 m BSL changes), with near complete collapse during the Miocene Climate Optimum (17–14.8 Ma). Both the BSL and RSL estimates have markedly higher Oligocene to Early Miocene Myr-scale amplitudes (20–60 m) than recently published δ18O-based estimates (<20 m) and much lower estimates than those of Exxon Production Research (>100 m), leading us to reject those estimates. The US Mid-Atlantic margin RSL was dominated by GMGSL but was overprinted by changes in mantle dynamic topography on the several Myr scale, showing approximately 50 m higher Eocene estimates and regionally propagating Miocene RSL changes. |
| format | Article |
| id | doaj-art-1441315b242343cf828dcff31601f19e |
| institution | Kabale University |
| issn | 2634-730X |
| language | English |
| publishDate | 2024-12-01 |
| publisher | Frontiers Media S.A. |
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| series | Earth Science, Systems and Society |
| spelling | doaj-art-1441315b242343cf828dcff31601f19e2025-01-10T14:04:55ZengFrontiers Media S.A.Earth Science, Systems and Society2634-730X2024-12-014110.3389/esss.2023.10091Global Mean and Relative Sea-Level Changes Over the Past 66 Myr: Implications for Early Eocene Ice SheetsK. G. Miller0W. J. Schmelz1J. V. Browning2Y. Rosenthal3A. V. Hess4R. E. Kopp5J. D. Wright61Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, United States1Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, United States1Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, United States1Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, United States1Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, United States1Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, United States1Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, United StatesWe estimate ice-volume driven (barystatic; BSL) sea-level changes for the Cenozoic using new Mg/Ca data from 58 to 48 Ma and a revised analysis of Mg/Ca trends over the past 66 Myr. We combine records of BSL, temperature-driven sea level, and long-term ocean basin volume variations to derive a new global mean geocentric sea level (GMGSL; “eustatic”) estimate. Bayesian analysis with Gaussian process priors shows that our BSL estimate shares a component that covaries on the Myr scale with “backstripped” relative sea-level (RSL) estimates (accounting for compaction, loading, and thermal subsidence) from the US Mid-Atlantic Coastal Plain, validating our method and estimates with errors of ±10 m. Peak warmth, elevated GMGSL and BSL, high CO2, and ice-free conditions occurred at times in the Paleocene to Eocene (ca. 64, 57.5, 35 Ma) and in much of the Early Eocene (55–48 Ma). However, our new results show that the Early Eocene was punctuated at specific times by several Myr-scale sea level lowerings (∼20–40 m) that require growth and decay of significant continental ice sheets even in the supposedly “ice-free” world. Continental-scale ice sheets waxed and waned beginning ca. 34 Ma (>50 m BSL changes), with near complete collapse during the Miocene Climate Optimum (17–14.8 Ma). Both the BSL and RSL estimates have markedly higher Oligocene to Early Miocene Myr-scale amplitudes (20–60 m) than recently published δ18O-based estimates (<20 m) and much lower estimates than those of Exxon Production Research (>100 m), leading us to reject those estimates. The US Mid-Atlantic margin RSL was dominated by GMGSL but was overprinted by changes in mantle dynamic topography on the several Myr scale, showing approximately 50 m higher Eocene estimates and regionally propagating Miocene RSL changes.https://www.lyellcollection.org/doi/10.3389/esss.2023.10091global mean geocentric sea levelbarystatic (ice-volume) sea levelrelative sea levelclimateCenozoic (past 66 million years) |
| spellingShingle | K. G. Miller W. J. Schmelz J. V. Browning Y. Rosenthal A. V. Hess R. E. Kopp J. D. Wright Global Mean and Relative Sea-Level Changes Over the Past 66 Myr: Implications for Early Eocene Ice Sheets Earth Science, Systems and Society global mean geocentric sea level barystatic (ice-volume) sea level relative sea level climate Cenozoic (past 66 million years) |
| title | Global Mean and Relative Sea-Level Changes Over the Past 66 Myr: Implications for Early Eocene Ice Sheets |
| title_full | Global Mean and Relative Sea-Level Changes Over the Past 66 Myr: Implications for Early Eocene Ice Sheets |
| title_fullStr | Global Mean and Relative Sea-Level Changes Over the Past 66 Myr: Implications for Early Eocene Ice Sheets |
| title_full_unstemmed | Global Mean and Relative Sea-Level Changes Over the Past 66 Myr: Implications for Early Eocene Ice Sheets |
| title_short | Global Mean and Relative Sea-Level Changes Over the Past 66 Myr: Implications for Early Eocene Ice Sheets |
| title_sort | global mean and relative sea level changes over the past 66 myr implications for early eocene ice sheets |
| topic | global mean geocentric sea level barystatic (ice-volume) sea level relative sea level climate Cenozoic (past 66 million years) |
| url | https://www.lyellcollection.org/doi/10.3389/esss.2023.10091 |
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