Paleogene Marine and Terrestrial Development of the West Antarctic Rift System

Coenen, J.J.; Scherer, Reed P.; Baudoin, Patrick; Warny, Sophie; Castañeda, Isla S.; Askin, Rosemary A.

doi:10.1029/2019gl085281

Cited by 18 publications

(21 citation statements)

References 68 publications

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“…This in turn makes interpreting past WAIS dynamics particularly challenging. Ongoing and future acquisition of geophysical data sets (e.g., Tinto et al, 2019) and geological data from ocean and subice drilling (e.g., Coenen et al, 2020) may lead to significant advances in our understanding of the geological and topographic evolution of West Antarctica beyond what is currently captured by continental paleotopography models. Indeed, the ice sheet model results presented in this study highlight the importance of robust paleotopographic reconstructions for understanding past AIS behavior and sensitivity and continued improvement of these reconstructions through acquisition of datasets proximal and distal to the Antarctic continent is an important priority for future research.…”

Section: Discussionmentioning

confidence: 99%

Long‐Term Increase in Antarctic Ice Sheet Vulnerability Driven by Bed Topography Evolution

Paxman

Gasson

Jamieson

et al. 2020

Geophysical Research Letters

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Ice sheet behavior is strongly influenced by the bed topography. However, the effect of the progressive temporal evolution of Antarctica's subglacial landscape on the sensitivity of the Antarctic Ice Sheet (AIS) to climatic and oceanic change has yet to be fully quantified. Here we investigate the evolving sensitivity of the AIS using a series of data-constrained reconstructions of Antarctic paleotopography since glacial inception at the Eocene-Oligocene transition. We use a numerical ice sheet model to subject the AIS to schematic climate and ocean warming experiments and find that bed topographic evolution causes a doubling in ice volume loss and equivalent global sea level rise. Glacial erosion is primarily responsible for enhanced ice sheet retreat via the development of increasingly low-lying and reverse sloping beds over time, particularly within near-coastal subglacial basins. We conclude that AIS sensitivity to climate and ocean forcing has been substantially amplified by long-term landscape evolution. Plain Language Summary The Antarctic Ice Sheet is situated above a large landmass, the geometry of which is an important control on the behavior of the ice sheet and how it responds to climatic change. However, Antarctica's subglacial landscape has evolved significantly since the formation of the first ice sheets approximately 34 million years ago, which implies that the sensitivity of the ice sheet to climate change may also have changed over time. Our ice sheet model experiments show that the progressive evolution of Antarctica's bed topography has enhanced the sensitivity of the Antarctic Ice Sheet to climate and ocean warming, meaning that a greater volume of ice is lost for a given warming scenario when using the modern topography compared to past topographies. In particular, the lowering of bed elevations by glacial erosion has caused a notable increase in ice sheet sensitivity within subglacial basins close to the ice sheet margin.

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Section: Discussionmentioning

confidence: 99%

Long‐Term Increase in Antarctic Ice Sheet Vulnerability Driven by Bed Topography Evolution

Paxman

Gasson

Jamieson

et al. 2020

Geophysical Research Letters

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“…Before the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) Project, the only sediment samples retrieved from beneath RIS were collected at site J9 (Figure 1a) as part of the RIS Project (Clough & Hansen, 1979). Sediments from J9, along with sediments from beneath the Siple Coast ice streams flowing into RIS (Figure 1a), contain Miocene, Pliocene, and Pleistocene aged microfossils (Coenen et al, 2019; Harwood et al, 1989; Scherer, 1991, Scherer et al, 1998), as well as measurable radiocarbon (Kingslake et al, 2018). Knowledge that diachronous marine influence on subglacial sediments introduces a chronologic range on the order of millions of years should thus raise caution on how time‐diagnostic data from subglacial sediments are interpreted.…”

Section: Introductionmentioning

confidence: 99%

“…Roosevelt Island 0 0 0 0 0 50 50 50 50 50 0 0 50 50 50 50 5 0 0 0 0 0 0 0 0 0 0 100 100 100 00 100 00 0 0 0 0 0 ice ice ice ice ce ce e i ve ve ve ve ve ve ve ve ve v loc loc loc loc loc loc loc oc o o o o o ity ity ty ty ity y y ty y ty ity ity ity ity y y y y y y [m [m [m [m [m [m [m [m [m [ [ [ a a a a a a a a a a a a a -1 - (Mouginot et al, 2019) overlain on an imagery mosaic (Scambos et al, 2007), with active subglacial lake areas (blue polygons; Siegfried & Fricker, 2018) and grounding line (white; Depoorter et al, 2013) Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) Project, the only sediment samples retrieved from beneath RIS were collected at site J9 (Figure 1a) as part of the RIS Project (Clough & Hansen, 1979). Sediments from J9, along with sediments from beneath the Siple Coast ice streams flowing into RIS (Figure 1a), contain Miocene, Pliocene, and Pleistocene aged microfossils (Coenen et al, 2019;Harwood et al, 1989;Scherer, 1991, Scherer et al, 1998, as well as measurable radiocarbon (Kingslake et al, 2018). Knowledge that diachronous marine influence on subglacial sediments introduces a chronologic range on the order of millions of years should thus raise caution on how time-diagnostic data from subglacial sediments are interpreted.…”

Section: Introductionmentioning

confidence: 99%

Mid‐Holocene Grounding Line Retreat and Readvance at Whillans Ice Stream, West Antarctica

Venturelli

Siegfried

Roush

et al. 2020

Geophysical Research Letters

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Understanding ice sheet evolution through the geologic past can help constrain ice sheet models that predict future ice dynamics. Existing geological records of grounding line retreat in the Ross Sea, Antarctica, have been confined to ice‐free and terrestrial archives, which reflect dynamics from periods of more extensive ice cover. Therefore, our perspective of grounding line retreat since the Last Glacial Maximum remains incomplete. Sediments beneath Ross Ice Shelf and grounded ice offer complementary insight into the southernmost extent of grounding line retreat, yielding a more complete view of ice dynamics during deglaciation. Here we thermochemically separate the youngest organic carbon to estimate ages from sediments extracted near the Whillans Ice Stream grounding line to provide direct evidence of mid‐Holocene (7.5–4.8 kyr B.P.) grounding line retreat in that region. Our study demonstrates the utility of accurately dated, grounding‐line‐proximal sediment deposits for reconstructing past interactions between marine and subglacial environments.

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“…These results could be interpreted as lending to support to the suggestion that a significant highland plateau and thickened crust existed in West Antarctica prior to extension, of which the Transantarctic Mountains are a remnant (Bialas et al, 2007;Huerta, 2007). Terrestrial and marine microfossil assemblages obtained via sub-ice drilling near the Siple Coast are indicative of low-elevation coastal plain and shallow marine palaeoenvironments during the Eocene (Coenen et al, 2019). This finding…”

Section: West Antarctic Rift Systemmentioning

confidence: 79%

Antarctic palaeotopography

Paxman

2021

Memoirs

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The development of a robust understanding of the response of the Antarctic Ice Sheet to present and projected future climatic change is a matter of key global societal importance. Numerical ice sheet models that simulate future ice sheet behaviour are typically evaluated with recourse to how well they reproduce past ice sheet behaviour, which is constrained by the geological record. However, subglacial topography, a key boundary condition in ice sheet models, has evolved significantly throughout Antarctica's glacial history. Since mantle processes play a fundamental role in the generation and modification of topography over geological timescales, an understanding of the interactions between the Antarctic mantle and palaeotopography is crucial for developing more accurate simulations of past ice sheet dynamics. This chapter provides a review of the influence of the Antarctic mantle on the long-term evolution of the subglacial landscape, through processes including structural inheritance, flexural isostatic adjustment, lithospheric cooling and thermal subsidence, volcanism and dynamic topography. The uncertainties associated with reconstructing these processes through time are discussed, as are important directions for future research and the implications of the evolving subglacial topography for the response of the Antarctic Ice Sheet to climatic and oceanographic change.

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Paleogene Marine and Terrestrial Development of the West Antarctic Rift System

Cited by 18 publications

References 68 publications

Long‐Term Increase in Antarctic Ice Sheet Vulnerability Driven by Bed Topography Evolution

Long‐Term Increase in Antarctic Ice Sheet Vulnerability Driven by Bed Topography Evolution

Mid‐Holocene Grounding Line Retreat and Readvance at Whillans Ice Stream, West Antarctica

Antarctic palaeotopography

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