Inclusions in ice layers formed by melting and refreezing processes in a Greenland ice core

• Published in: Journal of Glaciology
• Main Authors: Kawakami, Kaoru, Iizuka, Yoshinori, Matoba, Sumito, Aoki, Teruo, Ando, Takuto
• Other Authors: Japan Society for the Promotion of Science
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2022
• Subjects: Greenland; Greenland ice core; ice core; Ice Sheet; Journal of Glaciology
• Online Access: http://dx.doi.org/10.1017/jog.2022.101; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143022001010

Abstract In recent decades, surface melting on the inland Greenland ice sheet has increased, leading to significant meltwater-refreezing in the snow and firn. Increased knowledge of the physical and chemical characteristics of these melt features (i.e., ice layers) is needed to help estimate future global sea-level rise. Here, using a combination of microscopy and spectroscopy, we investigate the size, shape, location, and chemical compositions of inclusions in 12 ice layers of the SIGMA-A ice core in the northwestern Greenland ice sheet (78°03′06″N, 67°37′42″W, 1490 m a.s.l.). In the ice layers, we found inclusions exceeding 30 μm diameter that could only be formed by melting–refreezing, which we classify into columnar-, particle-, and rod-like inclusions. We propose that the smaller columnar- and particle-like inclusions of solid Na 2 SO 4 ⋅10H 2 O and CaSO 4 ⋅2H 2 O form first, within the ice grains, followed by the larger rod-like inclusions of brines with mainly Na + and Cl − in grain boundaries. Our results suggest a new proxy that may help identify past warm climates in deeper ice cores in Greenland and for studying future ice sheet melting behavior.