Preprints
https://doi.org/10.5194/egusphere-2022-264
https://doi.org/10.5194/egusphere-2022-264
 
09 May 2022
09 May 2022
Status: this preprint is open for discussion.

Where to GreenDrill? Site selection for cosmogenic nuclide exposure dating of the bed of the Greenland Ice Sheet

Jason P. Briner1, Caleb K. Walcott1, Joerg M. Schaefer2, Nicolás Young2, Joseph A. MacGregor3, Kristin Poinar1, Benjamin A. Keisling2, Sridhar Anandakrishnan4, Mary R. Albert5, Tanner Kuhl6, and Grant Boeckmann6 Jason P. Briner et al.
  • 1Department of Geology, University at Buffalo, Buffalo, NY, 14260 USA
  • 2Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA
  • 3Cryospheric Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
  • 4Department of Geosciences, Penn State University, University Park, PA 16802, USA
  • 5U.S. Ice Drilling Program, Thayer School of Engineering, Dartmouth College, Hanover, NH, USA Ice Drilling Program
  • 6U.S. Ice Drilling Program, University of Wisconsin-Madison, Madison, WI, USA

Abstract. Direct observations of the size of the Greenland Ice Sheet during Quaternary interglaciations are sparse yet valuable for testing numerical models of ice sheet history and sea level contribution. Recent measurements of cosmogenic nuclides in bedrock from beneath the Greenland Ice Sheet collected during past deep drilling campaigns reveal that the ice sheet was significantly smaller, and perhaps largely absent, sometime during the past 1.1 million years. These discoveries from decades-old basal samples motivate new, targeted sampling for cosmogenic nuclide analysis beneath the ice sheet. Current drills available for retrieving bed material from the US Ice Drilling Program require <700 m ice thickness and a frozen bed, while quartz-bearing bedrock lithologies are required for measuring a large suite of cosmogenic nuclides. We find that these and other requirements yield only ~3.4 % of the Greenland Ice Sheet bed as a suitable drilling target using presently available technology. Additional factors related to scientific questions of interest are which areas of the present ice sheet are the most sensitive to warming, where a retreating ice sheet would expose bare ground rather than leave a remnant ice cap, and which areas are most likely to remain frozen bedded throughout glacial cycles and thus best preserve cosmogenic nuclides? Here we identify locations beneath the Greenland Ice Sheet that are best suited for potential future drilling and analysis. These include sites bordering Inglefield Land in northwestern Greenland, near Victoria Fjord and Mylius-Erichsen Land in northern Greenland, and inland from the alpine topography along the ice margin in eastern and northeastern Greenland.

Jason P. Briner et al.

Status: open (until 04 Jul 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Jason P. Briner et al.

Jason P. Briner et al.

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Short summary
The 7.4 meters of sea-level-equivalent stored as Greenland ice is getting smaller every year. The uncertain trajectory of ice loss could be better understood with knowledge of the ice sheet's response to past climate change. Within the bedrock below the present-day ice sheet is an archive of past ice sheet history. We analyze all available data from Greenland to create maps showing where on the ice sheet scientists can drill, using currently available drills, to obtain sub-ice materials.