Holocene climate changes reflected in a diatom succession from Basaltsø, East Greenland
Bibliographic record
Abstract
Information on Holocene lacustrine diatom records from Greenland is rare. Here, a complete Holocene diatom succession is described from a sediment core recovered from Basaltsø, an arctic lake on Geographical Society Ø, eastern Greenland. Based on radiocarbon measurements on plant material, the upper 2.42 m of the 9.85 m long sediment sequence represent the Holocene sedimentological record in this area from about 10 000 calibrated (cal.) years BP. The diatom assemblages in Basaltsø are dominated by only a few species. Four stratigraphic diatom zones could be distinguished. During the early Holocene, mainly Staurosira construens (Ehr.) Williams et Round, Nitzschia amphibia Grunow, and Pinnularia mesolepta (Ehr.) W. Smith were the dominant taxa. After this initial stage, between 9600 and 5000 cal. years BP, Staurosirella pinnata (Ehr.) Williams et Round was the most abundant diatom species. From 4500 to 500 cal. years BP, the diatom assemblage was characterized by the co-occurrence of several taxa, including S. construens. S. pinnata, Kolbesia suchlandtii (Hust.) Kingston, and Cyclotella sp. A (rossiitripartitacomensis complex) as the main contributors. Finally, from 500 cal. years BP, the diatom assemblage was clearly dominated by Cyclotella sp. A, Cyclotella pseudostelligera Hustedt, and Sellaphora spp. The Holocene relative frequencies of S. pinnata and S. construens clearly correlate with the total diatom valve concentration, the Betula and Salix pollen percentage in Basaltsø, and the oxygen isotope record from the Renland ice core. This suggests that S. pinnata and S. construens are temperature-sensitive species that responded on the general climatic development in eastern Greenland during the Holocene. The diatom record together with the pollen and geochemical data of Basaltsø indicate to the Holocene climatic optimum on Geographical Society Ø from ca. 9000 to 6500 cal. years BP.Key words: Arctic, Greenland, Holocene, diatoms, paleolimnology, environmental change.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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 teacher head, 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".