Late Pleistocene changes in terrestrial biomarkers in sediments from the central Arctic Ocean
Biomarkers in Late Pleistocene sediments collected from the Integrated Ocean Drilling Program (IODP)-Arctic Coring Expedition (ACEX) Hole M0004C (central Arctic Ocean) were investigated. The major biomarkers are long-chain n-alkanes, n-fatty acids and n-alkan-1-ols, indicating fresh organic matter (...
| Published in: | Organic Geochemistry |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Pergamon
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| Subjects: | |
| Online Access: | http://hdl.handle.net/2115/33895 https://doi.org/10.1016/j.orggeochem.2008.04.009 |
| Summary: | Biomarkers in Late Pleistocene sediments collected from the Integrated Ocean Drilling Program (IODP)-Arctic Coring Expedition (ACEX) Hole M0004C (central Arctic Ocean) were investigated. The major biomarkers are long-chain n-alkanes, n-fatty acids and n-alkan-1-ols, indicating fresh organic matter (OM) derived predominantly from higher plants. The dominance of terrestrial biomarkers is attributed to severe OM degradation caused by slow sedimentation in oxygen-rich benthic water and/or low primary production due to permanent sea-ice coverage. Hopanes, representing thermally altered OM, tend to be abundant in samples with abundant ice rafted debris (IRD). An OM-rich dark grey layer deposited during marine isotope stage (MIS) 6 contains a significant amount of branched glycerol dialkyl glycerol tetraethers (branched GDGTs), suggesting ice erosion of organic-rich continental soil followed by transportation to the central Arctic by drifting ice. The labile–refractory index (i.e., the abundance ratio of long-chain n-alkan-1-ols to the sum of long-chain n-alkanes and long-chain n-alkan-1-ols) decreases above the dark grey layer, indicating that the OM became more refractory. This change suggests that coverage of the source region by OM-rich soil decreased because of extensive glacial erosion during MIS-6. |
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