Variations in Sr and Nd Isotopic Ratios of Mineral Particles in Cryoconite in Western Greenland

Frontiers in Digital Humanities

Takeuchi, Nozomu¹  Onuma, Yukihiko¹  Tanaka, Sota¹  Shimada, Rigen²  Uetake, Jun³  Nagatsuka, Naoko³  Nakano, Takanori⁴ 

[1] Department of Earth Sciences, Graduate School of Science, Chiba University, Chiba, Japan;Earth Observation Research Center, Japan Aerospace Exploration Agency, Ibaraki, Japan;National Institute of Polar Research, Tokyo, Japan;Research Institute for Humanity and Nature, Kyoto, Japan

关键词: Greenland;    cryoconite;    dark ice;    Sr and Nd isotopic ratios;    mineral source;   

DOI  :  10.3389/feart.2016.00093

学科分类：社会科学、人文和艺术（综合）

来源: Frontiers

【 摘 要 】

In order to better understand the source of minerals on the dark-colored ice, located in the Greenland ice sheet ablation zone, we analyzed the Sr and Nd isotopic ratios of minerals in cryoconite, which were collected from glaciers in northwest and southwest Greenland. We focused on the following: (i) comparison of the isotopes of minerals in cyroconite with those in sediments from local and distant areas, (ii) regional variations in western Greenland, and (iii) spatial variations across an individual a glacier. The mineral components of the cryoconite showed variable Sr and Nd isotopic ratios (87Sr/86Sr: 0.711335 to 0.742406, εNd (0): -33.1 to -22.9), which corresponded to those of the englacial dust and moraine on and around the glaciers but were significantly different from those of the distant deserts that have been considered to be primary sources of mineral dust on the Greenland Ice Sheet. This suggests that the minerals within the cryoconites were mainly derived from local sediments, rather than from distant areas. The Sr ratios in the northwestern region were significantly higher than those in the southwestern region. This is probably due to geological differences in the source areas, such as the surrounding glaciers in each region. The isotopic ratios further varied spatially within a glacier (Qaanaaq and Kangerlussuaq areas), indicating that the silicate minerals on the glaciers were derived not from a single source but from multiple sources, such as englacial dust and wind-blown minerals from the moraine surrounding the glaciers.

【 授权许可】

CC BY