Abstract
Natural mineral particulate matter deposited from aerosols and trapped in glaciers—herein defined as “cryodust”—may be an excellent indicator of atmospheric circulation, if terrestrial sources of dust can be identified. In this study, we analyzed the composition of cryodust in shallow ice cores taken from five glaciers in Southern Spitsbergen (Svalbard Archipelago, Northern Norway). The chemical composition, magnetic properties and radiogenic ages of individual grains were measured, where possible, to provide indicators of source areas. To identify mineral and rock fragments, solid particulates were examined by Scanning Electron Microscope fitted with a backscattered electron and Energy Dispersive Spectroscopic detectors. An Electron MicroProbe was employed for the U-Th-Pb chemical dating of monazite grains. Magnetic measurements comprised analyses of magnetic susceptibility (κ) vs. temperature (T) variations and determination of magnetic hysteresis parameters. Monazite ages span 445–423 Ma, consistent with mineral growth during the Caledonian orogeny. Caledonian rocks are exposed in the Nordaustlandet area of North-Eastern Svalbard, and this is the most probable source for monazite grains. Magnetic analyses show a predominance of ferrous (FeII) over ferric (FeIII) phases, consistent with a lack of input from subtropical sources. The results from both methods are consistent with local sources of dust from exposures in the Svalbard archipelago.
Highlights
The deposition of solid phases in glaciers is increasingly recognized as a critical component of theEarth’s climate system, due to their influence on the physicochemical properties of ice, with consequences for global-scale processes [1,2,3,4]
Age data of 1.3 Ga (Figure 8D), 1.6 Ga and 1.8 Ga may be derived from basement rocks, as such data were documented from granitic–gabbroic rocks of the Skålfjellet Subgroup in Southwest Spitsbergen [44]
Framboids are widely dispersed in rocks and sediments worldwide, we suggest that framboids in glacier ice stem from a local cryoconite microenvironment, in which biotic–abiotic interactions in the presence of sulfur and iron ions facilitated the formation of
Summary
The deposition of solid phases in glaciers is increasingly recognized as a critical component of the. Earth’s climate system, due to their influence on the physicochemical properties of ice, with consequences for global-scale processes [1,2,3,4]. The dust particles can contribute to deposits of cryoconite (named from Greek “kryos”—cold and “konis”—dust), infilling small water reservoirs on the ice surface, called cryoconite holes [15]. Whereas cryoconite is a mixture of biotic and abiotic elements, in this study, we coin the term “cryodust” to describe only abiotic particulate matter distributed within the ice of glaciers. This study aims to use the composition of solid abiotic particles deposited in glaciers of the Southern Spitsbergen to Atmosphere 2020, 11, 1325; doi:10.3390/atmos11121325 www.mdpi.com/journal/atmosphere
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