Evaluating Zr/Rb Ratio From XRF Scanning as an Indicator of Grain‐Size Variations of Glaciomarine Sediments in the Southern Ocean
Abstract The ln(Zr/Rb) count ratio derived from X‐ray fluorescence (XRF) core scanning holds potential as a high‐resolution tracer for grain‐size variations of glaciomarine sediments, and hence current strength. To evaluate this approach, we conducted high‐resolution grain‐size measurements, togethe...
Published in: | Geochemistry, Geophysics, Geosystems |
---|---|
Main Authors: | , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Wiley
2020
|
Subjects: | |
Online Access: | https://doi.org/10.1029/2020GC009350 https://doaj.org/article/a5ef1b2152a14ae68a71d5ba44d25778 |
id |
ftdoajarticles:oai:doaj.org/article:a5ef1b2152a14ae68a71d5ba44d25778 |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:a5ef1b2152a14ae68a71d5ba44d25778 2023-12-03T10:30:35+01:00 Evaluating Zr/Rb Ratio From XRF Scanning as an Indicator of Grain‐Size Variations of Glaciomarine Sediments in the Southern Ocean Li Wu David J. Wilson Rujian Wang Xuebo Yin Zhihua Chen Wenshen Xiao Mengxue Huang 2020-11-01T00:00:00Z https://doi.org/10.1029/2020GC009350 https://doaj.org/article/a5ef1b2152a14ae68a71d5ba44d25778 EN eng Wiley https://doi.org/10.1029/2020GC009350 https://doaj.org/toc/1525-2027 1525-2027 doi:10.1029/2020GC009350 https://doaj.org/article/a5ef1b2152a14ae68a71d5ba44d25778 Geochemistry, Geophysics, Geosystems, Vol 21, Iss 11, Pp n/a-n/a (2020) bottom currents glaciomarine sediment grain‐size iceberg rafted debris Southern Ocean XRF core scanning Zr/Rb Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 article 2020 ftdoajarticles https://doi.org/10.1029/2020GC009350 2023-11-05T01:35:52Z Abstract The ln(Zr/Rb) count ratio derived from X‐ray fluorescence (XRF) core scanning holds potential as a high‐resolution tracer for grain‐size variations of glaciomarine sediments, and hence current strength. To evaluate this approach, we conducted high‐resolution grain‐size measurements, together with Rb and Zr measurements by XRF core scanning and inductively coupled plasma‐mass spectrometry (ICP‐MS), on a series of sediment cores from different regions of the Southern Ocean. Downcore changes of the ln(Zr/Rb) count ratio from XRF core scanning are consistent with Zr/Rb concentration ratios derived from ICP‐MS analyses, even though Rb and Zr counts deviate significantly from concentrations due to specimen and matrix effects. The ln(Zr/Rb) count ratio displays discrepancies with the bulk mean grain‐size, but correlates well with the mean grain‐size of the sediment fractions that do not include unsorted sand delivered by ice‐rafting. These observations are supported by evidence from a grain‐size separation experiment, which indicates that Zr and Rb are concentrated in different grain‐size fractions. Consistent with its lack of sensitivity to coarse grain‐size fractions derived from ice‐rafting, the ln(Zr/Rb) ratio records similar trends to the sortable silt percent (SS%) and sortable silt mean (SS¯) grain‐size. Universal gradients exist in plots of SS% versus ln(Zr/Rb), and SS¯ versus ln(Zr/Rb), such that the ln(Zr/Rb) ratio provides a convenient way to estimate the magnitude of changes in SS% and SS¯. Overall, our results support the use of the ln(Zr/Rb) ratio as an indicator of bottom current strength in cases where the sediment is current‐sorted. Article in Journal/Newspaper Southern Ocean Directory of Open Access Journals: DOAJ Articles Southern Ocean Geochemistry, Geophysics, Geosystems 21 11 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
bottom currents glaciomarine sediment grain‐size iceberg rafted debris Southern Ocean XRF core scanning Zr/Rb Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 |
spellingShingle |
bottom currents glaciomarine sediment grain‐size iceberg rafted debris Southern Ocean XRF core scanning Zr/Rb Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 Li Wu David J. Wilson Rujian Wang Xuebo Yin Zhihua Chen Wenshen Xiao Mengxue Huang Evaluating Zr/Rb Ratio From XRF Scanning as an Indicator of Grain‐Size Variations of Glaciomarine Sediments in the Southern Ocean |
topic_facet |
bottom currents glaciomarine sediment grain‐size iceberg rafted debris Southern Ocean XRF core scanning Zr/Rb Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 |
description |
Abstract The ln(Zr/Rb) count ratio derived from X‐ray fluorescence (XRF) core scanning holds potential as a high‐resolution tracer for grain‐size variations of glaciomarine sediments, and hence current strength. To evaluate this approach, we conducted high‐resolution grain‐size measurements, together with Rb and Zr measurements by XRF core scanning and inductively coupled plasma‐mass spectrometry (ICP‐MS), on a series of sediment cores from different regions of the Southern Ocean. Downcore changes of the ln(Zr/Rb) count ratio from XRF core scanning are consistent with Zr/Rb concentration ratios derived from ICP‐MS analyses, even though Rb and Zr counts deviate significantly from concentrations due to specimen and matrix effects. The ln(Zr/Rb) count ratio displays discrepancies with the bulk mean grain‐size, but correlates well with the mean grain‐size of the sediment fractions that do not include unsorted sand delivered by ice‐rafting. These observations are supported by evidence from a grain‐size separation experiment, which indicates that Zr and Rb are concentrated in different grain‐size fractions. Consistent with its lack of sensitivity to coarse grain‐size fractions derived from ice‐rafting, the ln(Zr/Rb) ratio records similar trends to the sortable silt percent (SS%) and sortable silt mean (SS¯) grain‐size. Universal gradients exist in plots of SS% versus ln(Zr/Rb), and SS¯ versus ln(Zr/Rb), such that the ln(Zr/Rb) ratio provides a convenient way to estimate the magnitude of changes in SS% and SS¯. Overall, our results support the use of the ln(Zr/Rb) ratio as an indicator of bottom current strength in cases where the sediment is current‐sorted. |
format |
Article in Journal/Newspaper |
author |
Li Wu David J. Wilson Rujian Wang Xuebo Yin Zhihua Chen Wenshen Xiao Mengxue Huang |
author_facet |
Li Wu David J. Wilson Rujian Wang Xuebo Yin Zhihua Chen Wenshen Xiao Mengxue Huang |
author_sort |
Li Wu |
title |
Evaluating Zr/Rb Ratio From XRF Scanning as an Indicator of Grain‐Size Variations of Glaciomarine Sediments in the Southern Ocean |
title_short |
Evaluating Zr/Rb Ratio From XRF Scanning as an Indicator of Grain‐Size Variations of Glaciomarine Sediments in the Southern Ocean |
title_full |
Evaluating Zr/Rb Ratio From XRF Scanning as an Indicator of Grain‐Size Variations of Glaciomarine Sediments in the Southern Ocean |
title_fullStr |
Evaluating Zr/Rb Ratio From XRF Scanning as an Indicator of Grain‐Size Variations of Glaciomarine Sediments in the Southern Ocean |
title_full_unstemmed |
Evaluating Zr/Rb Ratio From XRF Scanning as an Indicator of Grain‐Size Variations of Glaciomarine Sediments in the Southern Ocean |
title_sort |
evaluating zr/rb ratio from xrf scanning as an indicator of grain‐size variations of glaciomarine sediments in the southern ocean |
publisher |
Wiley |
publishDate |
2020 |
url |
https://doi.org/10.1029/2020GC009350 https://doaj.org/article/a5ef1b2152a14ae68a71d5ba44d25778 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Geochemistry, Geophysics, Geosystems, Vol 21, Iss 11, Pp n/a-n/a (2020) |
op_relation |
https://doi.org/10.1029/2020GC009350 https://doaj.org/toc/1525-2027 1525-2027 doi:10.1029/2020GC009350 https://doaj.org/article/a5ef1b2152a14ae68a71d5ba44d25778 |
op_doi |
https://doi.org/10.1029/2020GC009350 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
21 |
container_issue |
11 |
_version_ |
1784256500008484864 |