Periodic Reporting for period 3 - OceaNice (Paleoceanography of the Ice-proximal Southern Ocean during Past Warm Climates)
Periodo di rendicontazione: 2022-02-01 al 2023-07-31
OceaNice addresses the role ocean conditions around Antarctica had on past fluctuations in size of the Antarctic ice sheet. It attempts to provide a Southern Ocean-wide understanding of ocean conditions during past warm climates by reconstructing surface ocean conditions in key past warm time intervals: The Pleistocene (1-0 Myr), the Pliocene (3.5-3 Myrs ago) and the mid-Miocene (17-14 Myrs ago). Oceanice groundtruths the use of organic-walled dinoflagellate cyst assemblages to reconstruct past paleoenvironmental conditions: sea ice, sea surface temperature and nutrients/upwelling by augmenting surface sediment sample datasets and developing transfer functions to translate fossil dinocyst assemblages to past surface ocean conditions in an accurate, quantitative way. It then applies these tools together with biomarker proxies for SST to Pleistocene glacial-interglacial fluctuations, notably to investigate the latitudinal migration of ocean frontal systems. It further applies these proxies to Pliocene and Miocene sedimentary records, to investigate past surface ocean conditions. The final part of the project involves high-resolution ocean modelling studies aimed to investigate the circum-Antarctic extrapolation of these reults and implications for heat transfer towards the Neogene ice sheet, to provide a more accurate representation of past ocean conditions for ice sheet modelling. The influence of the ocean in Antarctic ice sheet melt represents a key unknown in assessing the past sensitivity of Antarctic ice sheets to climate change, thus OceaNice directly delivers impact to improve our understanding of past, and future Antarctic ice dynamics.
Work performed in WP1:
1. Antarctic-proximal surface sediment sample compilation of dinoflagellate cysts
data is gathered and analysed. Paper is almost written and will likely be submitted mid 2022.
This paper will further strengthen the use of dinoflagellate cyst assemblages for paleoceanographic reconstructions (sea ice, temperature, nutrients).
2. dinocyst-and biomarker-based reconstruction of the subtropical front latitudinal migrations around Tasmania:
Samples are gathered, analyses done, paper half-written, likely submitted after Summer 2022.
This paper demonstrates the use of dinocysts to reconstruct past migrations of frontal systems.
3. late Pleistocene paleoceanographic conditions offshore Sabrina coast, Antarctica
Samples are gathered, analyses nearly done, paper to be written.
4. Compilation of Southern Ocean sea surface temperature reconstructions of MIS 10-12.
This literature overview will show the regional and latitudinal variability of SST changes across some of the most prominent glacial-interglacial transitions of the Pleistocene, from the cold glacial MIS12 via the warmer-than-modern MIS11 to the cold glacial MIS10. All data gathered, paper almost submitted.
5. reconstructing latitudinal SST gradients at MIS4-6.
This paper will show a novel way of reconstructing migrating frontal systems through comparison of two SST records, ideally placed in two latitudinally separated sectors of the Southern Ocean.
Paper in second round of review.
6. quantitative oceanographic reconstructions using modern dinocyst assemblages as training set.
PD3 Martin Schobben hired and trained, modelling code written, development of shiny app in progress.
Work peformed in WP2:
1. Neogene paleoceanographic evolution of the Subtropical Front (ODP Site 1168)
The samples are gathered, processed in the lab for palynology, biomarkers and washed for foraminifera. Analyses (dinocyst assemblage counts, TEX86 analysis for SST and stable isotope analyses for clumped isotope geochemistry) are done, one paper almost submitted, second paper half-way written.
The results portray an exciting picture of trends, rythms and aberrations in oceanographic conditions at the subtropical front: trends can be compared to those scattered records at ice proximal locations for a reconstruction of latitudinal SST gradients across the Southern Ocean. 4 papers are envisioned from this project (presenting the biomarkers, dinocysts, clumped isotope and mid-Pliocene high resolution data, respectively).
2. Latitudinal migrations of the subtropical front at the Agulhas Plateau during the Pliocene (IODP Site U1475).
This project has the same setup as above but then for the subtropical front at the Agulhas Plateau. The results will be presented in 2 papers, of which one led by PhD1 Suning Hou.
Work performed in WP3:
For WP3, training of the hired staff in Parcels has been completed, and the first project tracing ice bergs in the Eocene high-resolution model progresses has progressed. First paper on the oceanographic consequences of the evolution of the Tasmanian Gateway and Drake Passage is now published with PD2 as PI. PD3 has furthermore contributed to many OceaNice projects with her modelling skills.
1. Antarctic-proximal surface sediment sample compilation of dinoflagellate cysts
data is gathered and analysed. Paper is almost written and will likely be submitted mid 2022.
This paper will further strengthen the use of dinoflagellate cyst assemblages for paleoceanographic reconstructions (sea ice, temperature, nutrients).
2. dinocyst-and biomarker-based reconstruction of the subtropical front latitudinal migrations around Tasmania:
Samples are gathered, analyses done, paper half-written, likely submitted after Summer 2022.
This paper demonstrates the use of dinocysts to reconstruct past migrations of frontal systems.
3. late Pleistocene paleoceanographic conditions offshore Sabrina coast, Antarctica
Samples are gathered, analyses nearly done, paper to be written.
4. Compilation of Southern Ocean sea surface temperature reconstructions of MIS 10-12.
This literature overview will show the regional and latitudinal variability of SST changes across some of the most prominent glacial-interglacial transitions of the Pleistocene, from the cold glacial MIS12 via the warmer-than-modern MIS11 to the cold glacial MIS10. All data gathered, paper almost submitted.
5. reconstructing latitudinal SST gradients at MIS4-6.
This paper will show a novel way of reconstructing migrating frontal systems through comparison of two SST records, ideally placed in two latitudinally separated sectors of the Southern Ocean.
Paper in second round of review.
6. quantitative oceanographic reconstructions using modern dinocyst assemblages as training set.
PD3 Martin Schobben hired and trained, modelling code written, development of shiny app in progress.
Work peformed in WP2:
1. Neogene paleoceanographic evolution of the Subtropical Front (ODP Site 1168)
The samples are gathered, processed in the lab for palynology, biomarkers and washed for foraminifera. Analyses (dinocyst assemblage counts, TEX86 analysis for SST and stable isotope analyses for clumped isotope geochemistry) are done, one paper almost submitted, second paper half-way written.
The results portray an exciting picture of trends, rythms and aberrations in oceanographic conditions at the subtropical front: trends can be compared to those scattered records at ice proximal locations for a reconstruction of latitudinal SST gradients across the Southern Ocean. 4 papers are envisioned from this project (presenting the biomarkers, dinocysts, clumped isotope and mid-Pliocene high resolution data, respectively).
2. Latitudinal migrations of the subtropical front at the Agulhas Plateau during the Pliocene (IODP Site U1475).
This project has the same setup as above but then for the subtropical front at the Agulhas Plateau. The results will be presented in 2 papers, of which one led by PhD1 Suning Hou.
Work performed in WP3:
For WP3, training of the hired staff in Parcels has been completed, and the first project tracing ice bergs in the Eocene high-resolution model progresses has progressed. First paper on the oceanographic consequences of the evolution of the Tasmanian Gateway and Drake Passage is now published with PD2 as PI. PD3 has furthermore contributed to many OceaNice projects with her modelling skills.
1. New compilation of surface sediment dinocyst assemblages demonstrating the strong relationship between dinocyst assemblages and surface ocean conditions (SST, nutrients, sea ice). Demonstration of an improved tool to reconstruct past conditions in the Southern Ocean
2. Application of this proxy to Pleistocene glacial-interglacial cycles (both ice-proximal and subtropical front)
3. Novel way of reconstructing Pleistocene frontal system change using paired latitudinally dispersed biomarker records
4. Evolution of the Neogene subtropical front at Tasmania, applies proxies under 1 and 2 to protray how the "gateway to the Southern Ocean" established, in context of ice-proximal conditions.
5. mid-Miocene evolution of bottom water temperatures at the subtropical front using clumped isotope geochemistry
6. mid-Pliocene evolution of the Agulhas system, showing how conditions changed in the agulhas oceanographic system, with profound implications for the transport of salt to the N Atlantic Ocean
7. Reconstruction of the paleoceanographic consequences of the widening of the Tasmanian Gateway.
8. Evaluation of late Eocene iceberg drift patterns using high-resolution ocean modelling and lagrangian iceberg tracing.
Expected results:
Publication of the above and:
1. Development of an open-source transfer function that uses surface sediment dinocyst assemblages as training set and quantifies past SST, sea ice conditions and nutrients.
2. Quantification of oceanographic conditions (SST, nutrients, sea ice) for the Pleistocene Southern Ocean across MIS 4-6 and MIS 12-10.
3. Coherent picture of the evolution of the Neogene subtropical front, in tandem with the ice-proximal oceanographic evolution.
2. Application of this proxy to Pleistocene glacial-interglacial cycles (both ice-proximal and subtropical front)
3. Novel way of reconstructing Pleistocene frontal system change using paired latitudinally dispersed biomarker records
4. Evolution of the Neogene subtropical front at Tasmania, applies proxies under 1 and 2 to protray how the "gateway to the Southern Ocean" established, in context of ice-proximal conditions.
5. mid-Miocene evolution of bottom water temperatures at the subtropical front using clumped isotope geochemistry
6. mid-Pliocene evolution of the Agulhas system, showing how conditions changed in the agulhas oceanographic system, with profound implications for the transport of salt to the N Atlantic Ocean
7. Reconstruction of the paleoceanographic consequences of the widening of the Tasmanian Gateway.
8. Evaluation of late Eocene iceberg drift patterns using high-resolution ocean modelling and lagrangian iceberg tracing.
Expected results:
Publication of the above and:
1. Development of an open-source transfer function that uses surface sediment dinocyst assemblages as training set and quantifies past SST, sea ice conditions and nutrients.
2. Quantification of oceanographic conditions (SST, nutrients, sea ice) for the Pleistocene Southern Ocean across MIS 4-6 and MIS 12-10.
3. Coherent picture of the evolution of the Neogene subtropical front, in tandem with the ice-proximal oceanographic evolution.