Directly dating postglacial Greenlandic land-surface emergence at high resolution using in situ 10Be

• Published in: Quaternary Research
• Main Authors: Bierman, PR, Rood, DH, Shakun, JD, Portenga, EW, Corbett, LB
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Cambridge University Press 2018
• Subjects: Science & Technology; Physical Sciences; Geography; Physical; Geosciences; Multidisciplinary; Physical Geography; Geology; Uplift; Isostasy; Glacier; Ice sheet; Emergence; Beach; Cosmogenic; Dating; RELATIVE SEA-LEVEL; LAURENTIDE ICE-SHEET; LAST GLACIAL MAXIMUM; COSMOGENIC BE-10; HOLOCENE HISTORY; ISOLATION BASINS; EAST GREENLAND; WEST GREENLAND; AREA; DEGLACIATION; 0403 Geology; 0406 Physical Geography and Environmental Geoscience; 2101 Archaeology; Paleontology; Greenland; Igaliku; Kangerlussuaq; East Greenland; glacier; greenlandic; Ice Sheet; Narsarsuaq
• Online Access: http://hdl.handle.net/10044/1/60605; https://doi.org/10.1017/qua.2018.6

Postglacial emergence curves are used to infer mantle rheology, delimit ice extent, and test models of the solid Earth response to changing ice and water loads. Such curves are rarely produced by direct dating of land emergence; rather, most rely on the presence of radiocarbon-datable organic material and inferences made between the age of sedimentary deposits and landforms indicative of former sea level. Here, we demonstrate a new approach, 10Be dating, to determine rates of postglacial land emergence in two different settings. In southern Greenland (Narsarsuaq/Igaliku), we date directly the exposure, as relative sea level fell, of gravel beaches and rocky outcrops allowing determination of rapid, post–Younger Dryas emergence. In western Greenland (Kangerlussuaq), we constrain Holocene isostatic response by dating the sequential stripping of terrace sediment driven by land-surface uplift, relative sea-level fall, and resulting fluvial incision. The technique we employ provides high temporal and elevation resolution important for quantifying rapid emergence immediately after deglaciation and less rapid uplift during the middle Holocene. 10Be-constrained emergence curves can improve knowledge of relative sea-level change by dating land emergence along rocky coasts, at elevations and locations where radiocarbon-datable sediments are not present, and without the lag time needed for organic material to accumulate.