Applications of cosmogenic nuclides to Laurentide Ice Sheet history and dynamics

Abstract

Ice sheets play a fundamental role within Earth's climate system and in shaping landscapes. Despite extensive research, the maximum extent and basal dynamics of the Laurentide Ice Sheet (LIS) during the last glacial cycle remain elusive and debated in many areas. Recently, cosmogenic nuclides (e.g., 36 Cl, 26 Al, 10 Be) have played an important role in improving our understanding of LIS extent and behavior. Applications of cosmogenic nuclides to LIS research include surface exposure dating of glacial features, constraining magnitudes of glacial erosion, addressing long-term subaerial exposure and ice sheet burial histories, and burial dating of glacial sediments. These techniques have contributed to the depiction of a more extensive LIS than previously reconstructed for the Last Glacial Maximum. In addition, cosmogenic nuclide research has defi nitively shown that the LIS covered intensely weathered terrain along its deeply dissected eastern margin, where there were steep gradients in the effectiveness of basal erosion related to basal thermal regime. Cosmogenic nuclide applications, those already employed as well as those yet to be discovered, will undoubtedly continue to contribute to our ever-improving understanding of ice sheet history and dynamics.

Too young or too old: Evaluating cosmogenic exposure dating based on an analysis of compiled boulder exposure ages

“…However, prior exposure appears to dominate in areas that have been preserved under non-erosive ice (cf. Briner et al, 2006a;Fabel et al, 2002) as illustrated by the palaeo-ice sheet relict boulder dataset (Fig. 3).…”

“…Owen et al, 2008) and demonstrating the ability of cold-based ice sheets to preserve even delicate pre-glacial landscape features (e.g. Briner et al, 2003Briner et al, , 2006aStroeven et al, 2002). However, the accuracy of cosmogenic exposure dating is limited by the basic physical principles of the method (Fabel and Harbor, 1999;Gosse and Phillips, 2001;Lal, 1991) and geological uncertainty (Briner et al, 2005a;Hallet and Putkonen, 1994;Putkonen and Swanson, 2003;Zech et al, 2005b).…”

“…However, only limited attempts exist to reconcile models and measurements (cf. Briner et al, 2006a;Putkonen and O'Neal, 2006;Putkonen and Swanson, 2003).…”

Erratics selection for cosmogenic nuclide exposure dating – an optimization approach

“…Terrestrial cosmogenic nuclide exposure dating (TCNED) is routinely used for direct numerical dating of moraines, enabling construction of robust chronologies for paleo-ice sheets retreat (e.g. Briner et al 2006;Rinterknecht et al 2006;Clark et al 2009;Small et al 2017). Stable erratics resting on moraines are usually targets for TCNED sampling (e.g.…”

Application of in-situ produced terrestrial cosmogenic nuclides to archaeology: A schematic review

“…Shrewder sampling, improved chemical sample preparation and analysis as well as a better understanding of the physical processes responsible for in-situ produced Terrestrial Cosmogenic Nuclides (TCNs) have significantly enhanced the reliability of the method since its conception (cf., GOSSE & PHILLIPS 2001). The best known application of TCNs is the dating of the Quaternary ice volume fluctuations from the records archived by mountain glaciers (e.g., IVY-OCHS et al 2006) and continental ice sheets (e.g., BRINER et al 2006). Moreover, TCN methods have been employed in dating volcanic (e.g., LICCIARDI et al 1999) and palaeoseismic events (e.g., BENEDETTI et al 2003) as well as to quantify surface and/or rock uplift (RITZ et al 2006) and incision rates (e.g., SCHALLER et al 2005).…”