Basal debris of the NEEM ice core, Greenland: a window into sub-ice-sheet geology, basal ice processes and ice-sheet oscillations

IF 2.8 3区地球科学 Q2 GEOGRAPHY, PHYSICAL

Journal of Glaciology Pub Date : 2023-05-17 DOI:10.1017/jog.2022.122

P. Blard, M. Protin, J. Tison, F. Fripiat, D. Dahl-Jensen, J. Steffensen, W. Mahaney, P. Bierman, A. Christ, L. Corbett, V. Debaille, T. Rigaudier, P. Claeys

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Abstract

Abstract We present new data from the debris-rich basal ice layers of the NEEM ice core (NW Greenland). Using mineralogical observations, SEM imagery, geochemical data from silicates (meteoric 10Be, εNd, 87Sr/86Sr) and organic material (C/N, δ13C), we characterize the source material, succession of previous glaciations and deglaciations and the paleoecological conditions during ice-free episodes. Meteoric 10Be data and grain features indicate that the ice sheet interacted with paleosols and eroded fresh bedrock, leading to mixing in these debris-rich ice layers. Our analysis also identifies four successive stages in NW Greenland: (1) initial preglacial conditions, (2) glacial advance 1, (3) glacial retreat and interglacial conditions and (4) glacial advance 2 (current ice-sheet development). C/N and δ13C data suggest that deglacial environments favored the development of tundra and taiga ecosystems. These two successive glacial fluctuations observed at NEEM are consistent with those identified from the Camp Century core basal sediments over the last 3 Ma. Further inland, GRIP and GISP2 summit sites have remained glaciated more continuously than the western margin, with less intense ice-substratum interactions than those observed at NEEM.

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格陵兰NEEM冰芯的基底碎屑:亚冰盖地质、基底冰过程和冰盖振荡的窗口

我们提出了来自NEEM冰芯(格陵兰岛西北部)富含碎屑的基底冰层的新数据。利用矿物学观测、扫描电镜图像、硅酸盐地球化学资料(大气10Be、εNd、87Sr/86Sr)和有机质资料(C/N、δ13C)，表征了冰期的物源、冰期和脱冰期的演替和无冰期的古生态条件。大气10Be数据和颗粒特征表明，冰盖与古土壤和侵蚀的新基岩相互作用，导致这些富含碎屑的冰层混合在一起。我们的分析还确定了西北格陵兰岛的四个连续阶段:(1)初始冰川期，(2)冰川推进1期，(3)冰川后退和间冰期，(4)冰川推进2期(当前冰盖发育)。C/N和δ13C数据表明，去冰环境有利于冻土带和针叶林生态系统的发育。在NEEM观测到的这两次连续的冰川波动与在近3 Ma的世纪营岩心基底沉积物中发现的冰川波动一致。在更内陆的地方，GRIP和GISP2峰顶的冰川持续时间比西部边缘更长，冰-基底相互作用的强度比NEEM观测到的要小。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Glaciology 地学-地球科学综合

CiteScore

5.80

自引率

14.70%

发文量

101

审稿时长

6 months

期刊介绍： Journal of Glaciology publishes original scientific articles and letters in any aspect of glaciology- the study of ice. Studies of natural, artificial, and extraterrestrial ice and snow, as well as interactions between ice, snow and the atmospheric, oceanic and subglacial environment are all eligible. They may be based on field work, remote sensing, laboratory investigations, theoretical analysis or numerical modelling, or may report on newly developed glaciological instruments. Subjects covered recently in the Journal have included palaeoclimatology and the chemistry of the atmosphere as revealed in ice cores; theoretical and applied physics and chemistry of ice; the dynamics of glaciers and ice sheets, and changes in their extent and mass under climatic forcing; glacier energy balances at all scales; glacial landforms, and glaciers as geomorphic agents; snow science in all its aspects; ice as a host for surface and subglacial ecosystems; sea ice, icebergs and lake ice; and avalanche dynamics and other glacial hazards to human activity. Studies of permafrost and of ice in the Earth’s atmosphere are also within the domain of the Journal, as are interdisciplinary applications to engineering, biological, and social sciences, and studies in the history of glaciology.