Sulaymonova VA, Fuchs MC, Gloaguen R, Möckel R, Merchel S, Rudolph M, Krbetschek MR. Feldspar flotation as a quartz-purification method in
cosmogenic nuclide dating: A case study of fluvial sediments from the Pamir.
MethodsX 2018;
5:717-726. [PMID:
30094201 PMCID:
PMC6070659 DOI:
10.1016/j.mex.2018.06.014]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 06/26/2018] [Indexed: 11/16/2022] Open
Abstract
Our flotation cell is built of borosilicate glass, holds up to 90 g of sample, and achieves quartz and feldspar separation in ≤2 h.
The procedure uses air bubbles to which the feldspars attach, 0.2% HF to reduce the surface energy of quartz, dodecylamine solution as a feldspar collector, and operates at a pH range of 2.4–2.7 at room temperature.
We trace the stepwise enrichment of quartz by X-ray diffraction analysis, which shows that froth flotation is the decisive step to reach 95–100% purity from the initial 23–46%.
Cosmogenic nuclide (CN) dating relies on specific target minerals such as quartz as markers to identify geologic events, including the timing of landscape evolution. The presence of feldspar in sediment samples poses a challenge to the separation of quartz and affects the chemical procedures for extracting the radioactive CNs 10Be and 26Al. Additionally, feldspar contamination reduces the 26Al/27Al ratio, thus hinders the accurate determination of 26Al by accelerator mass spectrometry (AMS). Using fluvial sediment samples from Central Asia, which contain 16–50 weight percent (wt.%) of feldspar, we show that the standard physical separation and chemical cleaning-up procedures for quartz-enrichment reduces the feldspar content to only 9–47 wt.%. We present a new froth flotation mineral-separation device and procedure that allows for very effective quartz enrichment before CN chemistry. Our flotation cell, which has a volume of 600 cm3, is built of borosilicate glass, holds up to 90 g of sample, and achieves quartz and feldspar separation in ≤2 h for very feldspar-rich samples. We trace the stepwise enrichment of quartz to 95–100% purity with our procedure by X-ray diffraction analysis.
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