Fjord sediments in southern Greenland reveal Holocene glacial activity and organic carbon sequestration dynamics
Bibliographic record
Abstract
Sediments accumulating in Greenlandic fjords, situated between the ice sheet and the ocean, offer an excellent opportunity for investigating the environmental response to past climate variability and associated organic carbon sequestration processes. Our study focuses on a multiproxy approach of an almost undisturbed sedimentary record from Narsaq Sound in southern Greenland. A ~30-cm long multicore was collected on top of a ~11-m long gravity core during the MSM111 expedition in September 2022. Radiocarbon dating indicates a maximum age of approximately 12,000 years and a relatively constant sedimentation rate of ~1 m/kyr. A suite of whole-core analytical techniques was applied, including magnetic susceptibility measurements, X-ray fluorescence, and computer tomography scanning. Sediment samples were taken at intervals of 5–10 cm from the gravity core and at 1 cm intervals from the multicore. These samples were analyzed for total organic carbon, total nitrogen, stable isotopes of organic carbon and nitrogen, biomarkers (e.g., IP25), and organic carbon lability. Additionally, the elemental composition and dissolved organic carbon content of sediment pore-waters were assessed.Preliminary results show that sedimentological features such as IRD and bioturbation, as well as the elemental composition of the Narsaq record, reveal major changes related to the position of nearby glaciers and main climatic changes during the Holocene. Moreover, we found that the rather unusual element Niobium, derived from the surrounding drainage area, appears as a promising indicator of terrigenous sediment supply and past environmental change. Besides a clear change from predominantly terrestrial to more marine organic carbon during the transition from deglaciation to the thermal maximum era, the organic carbon is predominantly marine in origin during the entire Holocene. Our first results show that the investigated sediment cores from southern Greenland provide an excellent sedimentological and geochemical record reflecting past glacial activity and the impact of large scale climatic variability on local environmental changes since the last deglaciation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".