[A-CC27] アイスコアと古環境モデリング

[ACC27-08] グリーンランド北東部および北西部における過去100年間の鉱物組成変動の比較

*永塚 尚子¹、東 久美子^1,2、藤田 耕史³、小室 悠紀⁴、平林 幹啓¹、尾形 純¹、福田 かおり¹、塚川 佳美¹、北村 享太郎¹、米倉 綾香⁶、中澤 文男¹、大沼 友貴彦⁵、栗田 直幸³、Sune Olander Rasmussen⁷、Giulia Sinnl⁷、Trevor James Popp⁷、Dorthe Dahl-Jensen⁷ (1.国立極地研究所、2.総合研究大学院大学、3.名古屋大学、4.富士山環境研究センター、5.宇宙航空研究開発機構、6.マリン・ワーク・ジャパン 、7.コペンハーゲン大学)

キーワード：アイスコアダストの起源、グリーンランド、SEM-EDS分析

Mineral dust preserved in Greenland ice cores provide valuable insights into past climate and environmental changes. However, spatial and temporal variations in the Greenland ice-core dust sources during interglacial periods remain unclear because of low dust concentration. Here, we present the first continuous records of size, composition, and potential sources of silicate mineral dust from a northeastern Greenland ice core (EGRIP) over the last 100 years, using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). We highlight significant distinctions from a northwestern Greenland ice core (SIGMA-D). The EGRIP ice core dust displays low temporal variation, suggesting that the sources did not change dramatically during this period. Low compositional variability is distinct from the dust observed in the SIGMA-D ice-core, which shows multi-decadal variations due to increased contribution from the Greenland coastal region during warm periods. The subtle compositional variation in the EGRIP ice core dust likely reflects a significantly smaller contribution of local dust. Furthermore, significant differences in silicate mineral composition between the two ice cores imply transport from distinct geological origins. Analysis of mineralogy and trajectory data indicate potential dust sources, including Asian deserts, Northern Eurasia, and North America. The EGRIP ice core shows higher contributions from Asian deserts and Northern Eurasia, but lower from North America compared to the SIGMA-D ice core. Although subtle variations in dust compositions sugest no significant changes in the EGRIP ice-core dust sources, there may have been slight shifts during specific periods. A ternary clay mineralogy diagram and the elemental concentration ratios of the ice-core dust indicate a change in primary dust source contribution after 1970-1980. This change could be influenced by variations in atmospheric oscillations (such as the North Atlantic Oscillation and Atlantic Multidecadal Oscillation) and the input of Asian dust.