The Sediment Green‐Blue Color Ratio as a Proxy for Biogenic Silica Productivity Along the Chilean Margin
Abstract Sediment cores recently collected from the Chilean Margin during D/V JOIDES Resolution Expedition 379T (JR100) document variability in shipboard‐generated records of the green/blue (G/B) ratio. These changes show a strong coherence with benthic foraminiferal δ18O, Antarctic ice core records...
Published in: | Geochemistry, Geophysics, Geosystems |
---|---|
Main Authors: | , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Wiley
2022
|
Subjects: | |
Online Access: | https://doi.org/10.1029/2022GC010350 https://doaj.org/article/120877104097420c83a19adbf17aef64 |
id |
ftdoajarticles:oai:doaj.org/article:120877104097420c83a19adbf17aef64 |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:120877104097420c83a19adbf17aef64 2023-12-03T10:11:22+01:00 The Sediment Green‐Blue Color Ratio as a Proxy for Biogenic Silica Productivity Along the Chilean Margin Chen Li Vincent J. Clementi Samantha C. Bova Yair Rosenthal Laurel B. Childress James D. Wright Zhimin Jian Expedition 379T Scientists 2022-09-01T00:00:00Z https://doi.org/10.1029/2022GC010350 https://doaj.org/article/120877104097420c83a19adbf17aef64 EN eng Wiley https://doi.org/10.1029/2022GC010350 https://doaj.org/toc/1525-2027 1525-2027 doi:10.1029/2022GC010350 https://doaj.org/article/120877104097420c83a19adbf17aef64 Geochemistry, Geophysics, Geosystems, Vol 23, Iss 9, Pp n/a-n/a (2022) Chilean Margin sediment green‐to‐blue ratio opal flux Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 article 2022 ftdoajarticles https://doi.org/10.1029/2022GC010350 2023-11-05T01:35:55Z Abstract Sediment cores recently collected from the Chilean Margin during D/V JOIDES Resolution Expedition 379T (JR100) document variability in shipboard‐generated records of the green/blue (G/B) ratio. These changes show a strong coherence with benthic foraminiferal δ18O, Antarctic ice core records, and sediment lithology (e.g., higher diatom abundances in greener sediment intervals), suggesting a climate‐related control on the G/B. Here, we test the utility of G/B as a proxy for diatom productivity at Sites J1002 and J1007 by calibrating G/B to measured biogenic opal. Strong exponential correlations between measured opal% and the G/B were found at both sites. We use the empirical regressions to generate high‐resolution records of opal contents (opal%) on the Chilean Margin. Higher productivity tends to result in more reducing sedimentary conditions. Redox‐sensitive sedimentary U/Th generally co‐varies with the reconstructed opal% at both sites, supporting the association between sediment color, sedimentary U/Th, and productivity. Lastly, we calculated opal mass accumulation rate (MAR) at Site J1007 over the last ∼150,000 years. The G/B‐derived opal MAR record from Site J1007 largely tracks existing records derived from traditional wet‐alkaline digestion from the south and eastern equatorial Pacific (EEP) Ocean, with a common opal flux peak at ∼50 ka suggesting that increased diatom productivity in the EEP was likely driven by enhanced nutrient supply from the Southern Ocean rather than dust inputs as previously suggested. Collectively, our results identify the G/B ratio as a useful tool with the potential to generate reliable, high‐resolution paleoceanographic records that circumvent the traditionally laborious methodology. Article in Journal/Newspaper Antarc* Antarctic ice core Southern Ocean Directory of Open Access Journals: DOAJ Articles Antarctic Pacific Southern Ocean Geochemistry, Geophysics, Geosystems 23 9 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Chilean Margin sediment green‐to‐blue ratio opal flux Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 |
spellingShingle |
Chilean Margin sediment green‐to‐blue ratio opal flux Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 Chen Li Vincent J. Clementi Samantha C. Bova Yair Rosenthal Laurel B. Childress James D. Wright Zhimin Jian Expedition 379T Scientists The Sediment Green‐Blue Color Ratio as a Proxy for Biogenic Silica Productivity Along the Chilean Margin |
topic_facet |
Chilean Margin sediment green‐to‐blue ratio opal flux Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 |
description |
Abstract Sediment cores recently collected from the Chilean Margin during D/V JOIDES Resolution Expedition 379T (JR100) document variability in shipboard‐generated records of the green/blue (G/B) ratio. These changes show a strong coherence with benthic foraminiferal δ18O, Antarctic ice core records, and sediment lithology (e.g., higher diatom abundances in greener sediment intervals), suggesting a climate‐related control on the G/B. Here, we test the utility of G/B as a proxy for diatom productivity at Sites J1002 and J1007 by calibrating G/B to measured biogenic opal. Strong exponential correlations between measured opal% and the G/B were found at both sites. We use the empirical regressions to generate high‐resolution records of opal contents (opal%) on the Chilean Margin. Higher productivity tends to result in more reducing sedimentary conditions. Redox‐sensitive sedimentary U/Th generally co‐varies with the reconstructed opal% at both sites, supporting the association between sediment color, sedimentary U/Th, and productivity. Lastly, we calculated opal mass accumulation rate (MAR) at Site J1007 over the last ∼150,000 years. The G/B‐derived opal MAR record from Site J1007 largely tracks existing records derived from traditional wet‐alkaline digestion from the south and eastern equatorial Pacific (EEP) Ocean, with a common opal flux peak at ∼50 ka suggesting that increased diatom productivity in the EEP was likely driven by enhanced nutrient supply from the Southern Ocean rather than dust inputs as previously suggested. Collectively, our results identify the G/B ratio as a useful tool with the potential to generate reliable, high‐resolution paleoceanographic records that circumvent the traditionally laborious methodology. |
format |
Article in Journal/Newspaper |
author |
Chen Li Vincent J. Clementi Samantha C. Bova Yair Rosenthal Laurel B. Childress James D. Wright Zhimin Jian Expedition 379T Scientists |
author_facet |
Chen Li Vincent J. Clementi Samantha C. Bova Yair Rosenthal Laurel B. Childress James D. Wright Zhimin Jian Expedition 379T Scientists |
author_sort |
Chen Li |
title |
The Sediment Green‐Blue Color Ratio as a Proxy for Biogenic Silica Productivity Along the Chilean Margin |
title_short |
The Sediment Green‐Blue Color Ratio as a Proxy for Biogenic Silica Productivity Along the Chilean Margin |
title_full |
The Sediment Green‐Blue Color Ratio as a Proxy for Biogenic Silica Productivity Along the Chilean Margin |
title_fullStr |
The Sediment Green‐Blue Color Ratio as a Proxy for Biogenic Silica Productivity Along the Chilean Margin |
title_full_unstemmed |
The Sediment Green‐Blue Color Ratio as a Proxy for Biogenic Silica Productivity Along the Chilean Margin |
title_sort |
sediment green‐blue color ratio as a proxy for biogenic silica productivity along the chilean margin |
publisher |
Wiley |
publishDate |
2022 |
url |
https://doi.org/10.1029/2022GC010350 https://doaj.org/article/120877104097420c83a19adbf17aef64 |
geographic |
Antarctic Pacific Southern Ocean |
geographic_facet |
Antarctic Pacific Southern Ocean |
genre |
Antarc* Antarctic ice core Southern Ocean |
genre_facet |
Antarc* Antarctic ice core Southern Ocean |
op_source |
Geochemistry, Geophysics, Geosystems, Vol 23, Iss 9, Pp n/a-n/a (2022) |
op_relation |
https://doi.org/10.1029/2022GC010350 https://doaj.org/toc/1525-2027 1525-2027 doi:10.1029/2022GC010350 https://doaj.org/article/120877104097420c83a19adbf17aef64 |
op_doi |
https://doi.org/10.1029/2022GC010350 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
23 |
container_issue |
9 |
_version_ |
1784277720217157632 |