Abstract
Abstract. The ice–substrate interface is an important boundary condition for ice sheet modelling. The substrate affects the ice sheet by allowing sliding through sediment deformation and accommodating the storage and drainage of subglacial water. We present three datasets on a 1 : 5 000 000 scale with different geological parameters for the region that was covered by the ice sheets in North America, including Greenland and Iceland. The first dataset includes the distribution of surficial sediments, which is separated into continuous, discontinuous and predominantly rock categories. The second dataset includes sediment grain size properties, which is divided into three classes: clay, silt and sand, based on the dominant grain size of the fine fraction of the glacial sediments. The third dataset is the generalized bedrock geology. We demonstrate the utility of these datasets for governing ice sheet dynamics by using an ice sheet model with a simulation that extends through the last glacial cycle. In order to demonstrate the importance of the basal boundary conditions for ice sheet modelling, we changed the shear friction angle to account for a weaker substrate and found changes up to 40 % in ice thickness compared to a reference run. Although incorporation of the ice–bed boundary remains model dependent, our dataset provides an observational baseline for improving a critical weakness in current ice sheet modelling (https://doi.org/10.1594/PANGAEA.895889, Gowan et al., 2018b).
Highlights
Temperate ice sheets, such as the Laurentide and Eurasian ice sheets behaved differently depending on whether or not there was thick, continuous unconsolidated sediments underneath the ice (Clark and Walder, 1994)
We demonstrate the utility of these datasets for governing ice sheet dynamics by using an ice sheet model with a simulation that extends through the last glacial cycle
We have presented three datasets that present different types of geological data, including sediment distribution, grain size and bedrock geology for the regions in North America, Greenland and Iceland that were glaciated during the late Quaternary
Summary
Temperate ice sheets, such as the Laurentide and Eurasian ice sheets behaved differently depending on whether or not there was thick, continuous unconsolidated sediments underneath the ice (Clark and Walder, 1994). Many ice sheet modelling studies of the Laurentide Ice Sheet (Calov et al, 2002; Tarasov and Peltier, 2004; Gregoire et al, 2012; Abe-Ouchi et al, 2013) used the global sediment thickness map (Laske and Masters, 1997), which was designed for seismology applications rather than surficial processes This dataset reflects the thickness of Phanerozoic sedimentary rock that has not undergone significant metamorphism. In order to gain flexibility in parameterizing sediment parameters for ice sheet modelling, we present three datasets These data come from existing surficial geological maps when possible and are inferred from other studies where coverage is not complete. The mechanical strength and frictional resistance of the sediment (such as the shear friction angle), effects of hydrology (porosity and permeability of the sediments or rock, type of drainage), roughness of the bed and the erodibility of substrate
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