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Spatial variations of Sr–Nd isotopic ratios, mineralogical and elemental compositions of cryoconite in an Alaskan glacier
- Source :
- Annals of Glaciology. 59:147-158
- Publication Year :
- 2018
- Publisher :
- Cambridge University Press (CUP), 2018.
-
Abstract
- To understand the geological origins of minerals in cryoconite and the nutrients sources for microbes on glaciers, we analyzed the Sr–Nd isotopic ratios of the four mineral fractions in cryoconites including saline, carbonate, phosphate, silicate and the organic fraction obtained from Gulkana Glacier in Alaska. The isotopes in the silicate mineral fraction exhibited spatial variation within the glacier (87Sr/86Sr: 0.704533–0.709563, εNd (0): −16.0 to 0.5), which can be explained by the different mixing ratios of the two distinct sources: one of the sources is lateral and terminal moraines or soil, and the other is the medial moraine of the glacier. The minerals in the cryoconite at the lower sites in the glacier are likely derived from the former source, whereas those at the upper sites are from latter sources. The mineralogical and elemental compositions also support mixing of the silicate minerals from the two local sources. The Sr isotopic ratios of the organic fraction also showed spatial variation on the glacier in the middle sites – a trend similar to those of the phosphate fraction. The results suggest that the organic matter is mostly the byproducts of microbes using the phosphate minerals as a nutrient source.
- Subjects :
- chemistry.chemical_classification
010506 paleontology
geography
geography.geographical_feature_category
010504 meteorology & atmospheric sciences
Geochemistry
Glacier
01 natural sciences
Silicate
chemistry.chemical_compound
chemistry
Moraine
Silicate minerals
Cryoconite
Phosphate minerals
Organic matter
Terminal moraine
Geology
0105 earth and related environmental sciences
Earth-Surface Processes
Subjects
Details
- ISSN :
- 17275644 and 02603055
- Volume :
- 59
- Database :
- OpenAIRE
- Journal :
- Annals of Glaciology
- Accession number :
- edsair.doi...........3e74722bf1a4ef6a98667603a84b0392