A Revised Estimate of Early Pliocene Global Mean Sea Level Using Geodynamic Models of the Patagonian Slab Window
Abstract Paleoshorelines serve as measures of ancient sea level and ice volume but are affected by solid Earth deformation including processes such as glacial isostatic adjustment (GIA) and mantle dynamic topography (DT). The early Pliocene Epoch is an important target for sea‐level reconstructions...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Wiley
2023-02-01
|
| Series: | Geochemistry, Geophysics, Geosystems |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2022GC010648 |
| _version_ | 1797638101920645120 |
|---|---|
| author | Andrew Hollyday Jacqueline Austermann Andrew Lloyd Mark Hoggard Fred Richards Alessio Rovere |
| author_facet | Andrew Hollyday Jacqueline Austermann Andrew Lloyd Mark Hoggard Fred Richards Alessio Rovere |
| author_sort | Andrew Hollyday |
| collection | DOAJ |
| description | Abstract Paleoshorelines serve as measures of ancient sea level and ice volume but are affected by solid Earth deformation including processes such as glacial isostatic adjustment (GIA) and mantle dynamic topography (DT). The early Pliocene Epoch is an important target for sea‐level reconstructions as it contains information about the stability of ice sheets during a climate warmer than today. Along the southeastern passive margin of Argentina, three paleoshorelines date to early Pliocene times (4.8–5.5 Ma), and their variable present‐day elevations (36–180 m) reflect a unique topographic deformation signature. We use a mantle convection model to back‐advect present‐day buoyancy variations, including those that correspond to the Patagonian slab window. Varying the viscosity and initial tomography‐derived mantle buoyancy structures allows us to compute a suite of predictions of DT change that, when compared to GIA‐corrected shoreline elevations, makes it possible to identify both the most likely convection parameters and the most likely DT change. Our simulations illuminate an interplay of upwelling asthenosphere through the Patagonian slab window and coincident downwelling of the subducted Nazca slab in the mantle transition zone. This flow leads to differential upwarping of the southern Patagonian foreland since early Pliocene times, in line with the observations. Using our most likely DT change leads to an estimate of global mean sea level of 17.5 ± 6.4 m (1σ) in the early Pliocene Epoch. This confirms that sea level was significantly higher than present and can be used to calibrate ice sheet models. |
| first_indexed | 2024-03-11T12:58:46Z |
| format | Article |
| id | doaj.art-a71e5d55ed3642d8af7addc8250143c9 |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-03-11T12:58:46Z |
| publishDate | 2023-02-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-a71e5d55ed3642d8af7addc8250143c92023-11-03T16:55:39ZengWileyGeochemistry, Geophysics, Geosystems1525-20272023-02-01242n/an/a10.1029/2022GC010648A Revised Estimate of Early Pliocene Global Mean Sea Level Using Geodynamic Models of the Patagonian Slab WindowAndrew Hollyday0Jacqueline Austermann1Andrew Lloyd2Mark Hoggard3Fred Richards4Alessio Rovere5Lamont‐Doherty Earth Observatory Department of Earth and Environmental Sciences Columbia University NY New York USALamont‐Doherty Earth Observatory Department of Earth and Environmental Sciences Columbia University NY New York USALamont‐Doherty Earth Observatory Department of Earth and Environmental Sciences Columbia University NY New York USAResearch School of Earth Sciences Australian National University ACT Canberra AustraliaDepartment of Earth Science & Engineering Imperial College London London UKCenter for Marine Environmental Sciences MARUM University of Bremen (DE) Bremen GermanyAbstract Paleoshorelines serve as measures of ancient sea level and ice volume but are affected by solid Earth deformation including processes such as glacial isostatic adjustment (GIA) and mantle dynamic topography (DT). The early Pliocene Epoch is an important target for sea‐level reconstructions as it contains information about the stability of ice sheets during a climate warmer than today. Along the southeastern passive margin of Argentina, three paleoshorelines date to early Pliocene times (4.8–5.5 Ma), and their variable present‐day elevations (36–180 m) reflect a unique topographic deformation signature. We use a mantle convection model to back‐advect present‐day buoyancy variations, including those that correspond to the Patagonian slab window. Varying the viscosity and initial tomography‐derived mantle buoyancy structures allows us to compute a suite of predictions of DT change that, when compared to GIA‐corrected shoreline elevations, makes it possible to identify both the most likely convection parameters and the most likely DT change. Our simulations illuminate an interplay of upwelling asthenosphere through the Patagonian slab window and coincident downwelling of the subducted Nazca slab in the mantle transition zone. This flow leads to differential upwarping of the southern Patagonian foreland since early Pliocene times, in line with the observations. Using our most likely DT change leads to an estimate of global mean sea level of 17.5 ± 6.4 m (1σ) in the early Pliocene Epoch. This confirms that sea level was significantly higher than present and can be used to calibrate ice sheet models.https://doi.org/10.1029/2022GC010648geodynamicssea‐level changePlioceneglacial isostatic adjustmentmantle convectionPatagonia |
| spellingShingle | Andrew Hollyday Jacqueline Austermann Andrew Lloyd Mark Hoggard Fred Richards Alessio Rovere A Revised Estimate of Early Pliocene Global Mean Sea Level Using Geodynamic Models of the Patagonian Slab Window Geochemistry, Geophysics, Geosystems geodynamics sea‐level change Pliocene glacial isostatic adjustment mantle convection Patagonia |
| title | A Revised Estimate of Early Pliocene Global Mean Sea Level Using Geodynamic Models of the Patagonian Slab Window |
| title_full | A Revised Estimate of Early Pliocene Global Mean Sea Level Using Geodynamic Models of the Patagonian Slab Window |
| title_fullStr | A Revised Estimate of Early Pliocene Global Mean Sea Level Using Geodynamic Models of the Patagonian Slab Window |
| title_full_unstemmed | A Revised Estimate of Early Pliocene Global Mean Sea Level Using Geodynamic Models of the Patagonian Slab Window |
| title_short | A Revised Estimate of Early Pliocene Global Mean Sea Level Using Geodynamic Models of the Patagonian Slab Window |
| title_sort | revised estimate of early pliocene global mean sea level using geodynamic models of the patagonian slab window |
| topic | geodynamics sea‐level change Pliocene glacial isostatic adjustment mantle convection Patagonia |
| url | https://doi.org/10.1029/2022GC010648 |
| work_keys_str_mv | AT andrewhollyday arevisedestimateofearlyplioceneglobalmeansealevelusinggeodynamicmodelsofthepatagonianslabwindow AT jacquelineaustermann arevisedestimateofearlyplioceneglobalmeansealevelusinggeodynamicmodelsofthepatagonianslabwindow AT andrewlloyd arevisedestimateofearlyplioceneglobalmeansealevelusinggeodynamicmodelsofthepatagonianslabwindow AT markhoggard arevisedestimateofearlyplioceneglobalmeansealevelusinggeodynamicmodelsofthepatagonianslabwindow AT fredrichards arevisedestimateofearlyplioceneglobalmeansealevelusinggeodynamicmodelsofthepatagonianslabwindow AT alessiorovere arevisedestimateofearlyplioceneglobalmeansealevelusinggeodynamicmodelsofthepatagonianslabwindow AT andrewhollyday revisedestimateofearlyplioceneglobalmeansealevelusinggeodynamicmodelsofthepatagonianslabwindow AT jacquelineaustermann revisedestimateofearlyplioceneglobalmeansealevelusinggeodynamicmodelsofthepatagonianslabwindow AT andrewlloyd revisedestimateofearlyplioceneglobalmeansealevelusinggeodynamicmodelsofthepatagonianslabwindow AT markhoggard revisedestimateofearlyplioceneglobalmeansealevelusinggeodynamicmodelsofthepatagonianslabwindow AT fredrichards revisedestimateofearlyplioceneglobalmeansealevelusinggeodynamicmodelsofthepatagonianslabwindow AT alessiorovere revisedestimateofearlyplioceneglobalmeansealevelusinggeodynamicmodelsofthepatagonianslabwindow |