Abstract
Abstract. Our study is the first to demonstrate a high-temporal-resolution record of mineral composition in a Greenland ice core over the past 100 years. To reconstruct past variations in the sources and transportation processes of mineral dust in northwestern Greenland, we analysed the morphology and mineralogical composition of dust in the SIGMA-D ice core from 1915 to 2013 using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results revealed that the ice core dust consisted mainly of silicate minerals and that the composition varied substantially on multi-decadal and inter-decadal scales, suggesting that the ice core minerals originated from different geological sources in different periods during the past 100 years. The multi-decadal variation trend differed among mineral types. Kaolinite, which generally formed in warm and humid climatic zones, was abundant in colder periods (1950–2004), whereas mica, chlorite, feldspars, mafic minerals, and quartz, which formed in arid, high-latitude, and local areas, were abundant in warmer periods (1915–1949 and 2005–2013). Comparison to Greenland surface temperature records indicates that multi-decadal variation in the relative abundance of these minerals was likely affected by local temperature changes in Greenland. Trajectory analysis shows that the minerals were transported mainly from the western coast of Greenland in the two warming periods, which was likely due to an increase in dust sourced from local ice-free areas as a result of shorter snow/ice cover duration in the Greenland coastal region during the melt season caused by recent warming. Meanwhile, ancient deposits in northern Canada, which were formed in past warmer climates, seem to be the best candidate during the colder period (1950–2004). Our results suggest that SEM–EDS analysis can detect variations in ice core dust sources during recent periods of low dust concentration.
Highlights
Aeolian mineral dust in snow and ice on ice sheets provides key information about global and local climate change
The results revealed that the ice core dust consisted mainly of silicate minerals and that the composition varied substantially on multi-decadal and inter-decadal scales, suggesting that the ice core minerals originated from different geological sources in different periods during the past 100 years
The multi-decadal variation trend differed among mineral types
Summary
Aeolian mineral dust in snow and ice on ice sheets provides key information about global and local climate change. Dust concentrations in Greenland ice cores during the last glacial period were 10 to 100 times higher than those over the Holocene and were strongly correlated with temperature changes (as indicated by δ18O records; e.g. De Angelis et al, 1997; Mayewski et al, 1997; Fuhrer et al, 1999; Ruth et al, 2003; Schüpbach et al, 2018). Steffensen (1997) showed a systematic connection between dust volume distribution, total dust mass, and δ18O in the Greenland Ice Core Project (GRIP) ice core, indicating that climate changes appear to have modified the processes of formation, transport, and deposition of mineral dust in the same way over the last 120 000 years. It is important to reconstruct the variations in the sources and transportation processes of mineral dust in ice cores
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