Preprints
https://doi.org/10.5194/egusphere-2024-620
https://doi.org/10.5194/egusphere-2024-620
11 Mar 2024
 | 11 Mar 2024
Status: this preprint is open for discussion and under review for Climate of the Past (CP).

North American Pleistocene Glacial Erosion and Thin Pliocene Regolith Thickness Inferred from Data-Constrained Fully Coupled Ice-Climate-Sediment modelling

Matthew Drew and Lev Tarasov

Abstract. Beyond the impact of glacial isostatic adjustment, landscape evolution is typically neglected at large scale when considering the basal boundary condition for ice sheet and climate modelling over past glacial cycles. Erosion and changing sediment loads impact bed elevation, land/sea mask, and basal drag. To date, how the above affects past ice sheet evolution is unclear.

Constraining the role that Pliocene regolith may have played in Pleistocene glacial cycle variability requires bounds on the amount of regolith preceding those glacial cycles. However, quantitative bounds on regolith thickness at the spatial scale of the glaciated regions of North America are currently absent in the literature.

To address the above, we present an updated sediment production and transport model with dynamically calculated soft sediment mask, isostatic adjustment to dynamical sediment load and bedrock erosion, and a new subglacial hydrology model coupled to the Glacial Systems Model. The coupled model is capable of multi-million year integrations driven only by greenhouse gas concentration and insolation. The model passes a set of verification tests and conserves mass. We assess parametric sensitivity of sediment transport rates.

We compare the final sediment solutions in an ensemble of whole-Pleistocene simulations for a range of initial (Pliocene) regolith thicknesses against multiple estimates for present day drift thickness distribution, Quaternary sediment volume in the Atlantic Ocean, and erosion depth estimates. Consistency of modelling and data constraints requires a Pliocene regolith thickness of less than 50 m.

Matthew Drew and Lev Tarasov

Status: open (until 06 May 2024)

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Matthew Drew and Lev Tarasov
Matthew Drew and Lev Tarasov

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Short summary
We model the sediment-ice-climate system over North America for the last 2.58 Myr showing that ice sheets are capable of excavating features the size of the Hudson bay. This work provides a basis for reconstructing past landscapes important to climate modelling efforts, helping us to understand past earth system change.