Evaluating the reliability of grain-size sorting for organic biomarker analysis
Evaluating the reliability of grain-size sorting for organic biomarker analysis
Organic and inorganic geochemical proxies are fundamental for interpreting past climate variability. For inorganic analysis, marine sediments are often size fractionated to isolate foraminifera, while organic analysis employs subsamples of bulk sediment. Although previously sieved sediments could be used for biomarker analysis, this approach and potential methodological biases have not been assessed in pre-Holocene sediments. Here we explore lipid biomarkers (isoGDGTs, brGDGTs, n-alkanes) across grain-size fractions in Cenozoic marine sediments, assessing whether sieved sediments can be used to reconstruct paleoenvironmental change. We analyze biomarkers in fine (<63 μm) and coarse (>63 μm) grain-size fractions and compare various proxy metrics with those in bulk sediments. Our findings reveal a strong linear correlation between TEX86 in different size-fractions and bulk sediment (r2 = 0.85–0.94, both p < 0.001), indicating sea surface temperature (SST) reconstructions are viable using previously sieved sediments. MBT′5ME shows a weaker yet significant correlation between fine and bulk sediment (r2 = 0.70–0.81, both p < 0.001). In fine fractions, n-alkanes typically reflect the bulk sediment composition, whereas coarse sediments consistently underestimate bulk sediment chain length metrics, suggesting organo-mineral associations. Our results demonstrate GDGT-based temperature proxies can typically be analyzed using sieved sediments, whilst n-alkanes can be influenced by organo-mineral associations and contamination during processing. We assessed contamination from traditional processing techniques, determining sieving sediments into plastic beakers can introduce hydrocarbon contamination but this does not affect GDGT analysis. Our study confirms that archives of fine-grained sediment fractions can be resurrected for GDGT analysis, encouraging a re-examination of global stores of processed samples.
Hingley, Joe Steven
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Bray, Sargent
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Agterhuis, Tobias
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Foster, Gavin
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Wade, B.S.
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Whiteside, Jessica H.
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Inglis, Gordon
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17 February 2026
Hingley, Joe Steven
893da1dc-9ede-44f9-b6f4-d4443fb25286
Bray, Sargent
4075cb9d-6fc2-403f-8a94-df1a4e3196e4
Agterhuis, Tobias
1ba695c7-de95-40c6-ac4e-a64f360745c3
Foster, Gavin
fbaa7255-7267-4443-a55e-e2a791213022
Wade, B.S.
4caf9386-0e3f-479b-a491-6c8dff99dad1
Whiteside, Jessica H.
7d7d9398-2320-4ed1-b39e-5e5bf0174215
Inglis, Gordon
1651196d-916c-43cb-b5a0-9b3ecaf5d664
Hingley, Joe Steven, Bray, Sargent, Agterhuis, Tobias, Foster, Gavin, Wade, B.S., Whiteside, Jessica H. and Inglis, Gordon
(2026)
Evaluating the reliability of grain-size sorting for organic biomarker analysis.
Paleoceanography and Paleoclimatology, 41 (2).
(doi:10.1029/2025PA005289Digital Object Identifier (DOI)).
Abstract
Organic and inorganic geochemical proxies are fundamental for interpreting past climate variability. For inorganic analysis, marine sediments are often size fractionated to isolate foraminifera, while organic analysis employs subsamples of bulk sediment. Although previously sieved sediments could be used for biomarker analysis, this approach and potential methodological biases have not been assessed in pre-Holocene sediments. Here we explore lipid biomarkers (isoGDGTs, brGDGTs, n-alkanes) across grain-size fractions in Cenozoic marine sediments, assessing whether sieved sediments can be used to reconstruct paleoenvironmental change. We analyze biomarkers in fine (<63 μm) and coarse (>63 μm) grain-size fractions and compare various proxy metrics with those in bulk sediments. Our findings reveal a strong linear correlation between TEX86 in different size-fractions and bulk sediment (r2 = 0.85–0.94, both p < 0.001), indicating sea surface temperature (SST) reconstructions are viable using previously sieved sediments. MBT′5ME shows a weaker yet significant correlation between fine and bulk sediment (r2 = 0.70–0.81, both p < 0.001). In fine fractions, n-alkanes typically reflect the bulk sediment composition, whereas coarse sediments consistently underestimate bulk sediment chain length metrics, suggesting organo-mineral associations. Our results demonstrate GDGT-based temperature proxies can typically be analyzed using sieved sediments, whilst n-alkanes can be influenced by organo-mineral associations and contamination during processing. We assessed contamination from traditional processing techniques, determining sieving sediments into plastic beakers can introduce hydrocarbon contamination but this does not affect GDGT analysis. Our study confirms that archives of fine-grained sediment fractions can be resurrected for GDGT analysis, encouraging a re-examination of global stores of processed samples.
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Paleoceanog and Paleoclimatol - 2026 - Hingley - Evaluating the Reliability of Grain‐Size Sorting for Organic Biomarker
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Accepted/In Press date: 29 January 2026
Published date: 17 February 2026
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Local EPrints ID: 510852
URI: http://eprints.soton.ac.uk/id/eprint/510852
ISSN: 2572-4525
PURE UUID: 41d53aa9-b3f4-40c5-8213-5e0c5bb01122
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Date deposited: 22 Apr 2026 17:00
Last modified: 25 Apr 2026 03:09
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Author:
Joe Steven Hingley
Author:
Tobias Agterhuis
Author:
B.S. Wade
Author:
Jessica H. Whiteside
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