气候变化领域集成服务门户(CCPortal): Erosion rates in Fennoscandia during the past million years

CCPortal

DOI	10.1016/j.quascirev.2019.01.010
	Erosion rates in Fennoscandia during the past million years
	Jansen J.D.; Knudsen M.F.; Andersen J.L.; Heyman J.; Egholm D.L.
发表日期	2019
ISSN	0277-3791
起始页码	37
结束页码	48
卷号	207
英文摘要	The widespread existence of cosmogenic nuclides accumulated in bedrock prior to the last glaciation demonstrates the limited erosional efficacy of the most recent Fennoscandian and Laurentide ice sheets. Yet the deeper history of erosion in these landscapes repeatedly blanketed by ice remains essentially unknown. Here we present the first comprehensive ice sheet-wide analysis of cosmogenic 10 Be data (n = 953) from the Fennoscandian landscape. We find 64% of all sampled bedrock surfaces contain 10 Be inheritance, including >85% of blockfields and tors, and >50% of ice-carved terrain, in addition to 27% of ice-transported boulders. Recent ice sheets scoured landscapes well beyond glacial troughs and nuclide inventories reveal a patchy legacy of erosional effectiveness that diminishes at high elevations, such that 89% (n = 55) of bedrock samples retain inheritance above 1600 m. We exploit this widespread nuclide inheritance in a Markov chain Monte Carlo-based inversion model to estimate long-term erosion rates and surface exposure histories from 113 paired 10 Be– 26 Al bedrock samples. Nuclide inventories with or without inheritance convey equally important information about the erosional effectiveness of the last ice sheet. We define cosmogenic nuclide memory as the residence time of bedrock samples inside the nuclide-production window (≤2 m depth) where ∼ 80% of the total nuclide production occurs. The cosmogenic nuclide memory is set by mean erosion rate and varies from ∼10 ka for samples eroded >2 m during the last glaciation to > 1-Ma for the slowest erosion rates. We find that mean erosion rates are well constrained compared to the ratio of exposure to burial. The inclusion of bedrock erosion in our computations thwarts the capacity to constrain surface exposure history or identify former nunataks from paired 10 Be– 26 Al data. Ice-carved surfaces reflect diverse erosion histories that are not straightforward to interpret from surficial morphology alone. Relative to the ∼10 mm/kyr benchmark for polar ice masses, we report point-based mean erosion rates that vary by more than three orders of magnitude, with glacial troughs and areal-scour terrain eroding at ∼1 to >100 mm/kyr, blockfields at 0.8–16 mm/kyr, and tors at 0.8–7.7 mm/kyr (5 th –95th percentiles). © 2019 Elsevier Ltd
英文关键词	Bedrock glacial erosion; Cosmogenic nuclide memory; Markov chain Monte Carlo inversion; Scandinavia
语种	英语
scopus关键词	Erosion; Glacial geology; Glaciers; Isotopes; Markov processes; Monte Carlo methods; Bedrock surfaces; Cosmogenic nuclides; Glacial erosion; Laurentide ice sheets; Markov Chain Monte-Carlo; Nuclide production; Scandinavia; Three orders of magnitude; Ice; bedrock; cosmogenic radionuclide; erosion rate; glacial erosion; glacial hydrology; ice flow; ice sheet; last glaciation; Markov chain; Monte Carlo analysis; trough; Fennoscandia; Scandinavia
来源期刊	Quaternary Science Reviews
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/152015
作者单位	Department of Geoscience, Aarhus University, Aarhus, 8000, Denmark; Geological Survey of Norway, Trondheim, 7491, Norway; Department of Earth Sciences, University of Gothenburg, Göteborg, 40530, Sweden
推荐引用方式 GB/T 7714	Jansen J.D.,Knudsen M.F.,Andersen J.L.,et al. Erosion rates in Fennoscandia during the past million years[J],2019,207.
APA	Jansen J.D.,Knudsen M.F.,Andersen J.L.,Heyman J.,&Egholm D.L..(2019).Erosion rates in Fennoscandia during the past million years.Quaternary Science Reviews,207.
MLA	Jansen J.D.,et al."Erosion rates in Fennoscandia during the past million years".Quaternary Science Reviews 207(2019).