Central Arctic Lithostratigraphy: Implication for Sediment Transport and Paleoceanography
Bibliographic record
Abstract
Multiple cores from the Arctic were analyzed by XRF methods to determine the western Arctic lithostratigraphy as expressed in its geochemistry. In general, glacial and interglacial events have distinctly different chemistry. During glacial events, the sediments have elevated Ti, Fe, Rb, and Zr concentrations and depressed Sr and Mn concentrations. The opposite is true of the brown layers, where Ti, Fe, Rb and Zr are lower with higher levels of Mn and Sr. These data indicate that there are 18 chemically unique lithologic units (LUs) that exist among MIS-1 to MIS-16 age sediments. Isopach maps indicate two general depositional patterns appear to have existed during the late Quaternary. The first pattern is defined as a glacial depositional pattern based on sediment thicknesses present in Clark et al. (1980) SLUs F, H, J, and L. This pattern has the thickest deposits located on parts of the Northwind-Alpha Ridges as well as within the Makarov Basin. The second pattern is associated with interglacial deposits and is based on sediment thicknesses present in SLUs G, I, and K. The interglacial pattern is characterized by much thinner deposits especially for the central Arctic region. Based on the isopach sediment patterns, the potential source areas of the sediments deposited during the glacial and interglacial periods are slightly different. During glacial stages, a strong Canadian source area is suggested. During interglacial stages a Canadian source area exists for deposits in the Canadian Basin, and a potential mixture of Canadian and Russian source areas for sediments located along the Trans-Polar Drift between the Mendeleev-Lomonosov Ridges. Stratigraphic correlations indicate that the western Arctic, central Lomonosov Ridge, and eastern Arctic are geochemically different suggesting different sources for each area. Analysis of the coarse ice-rafted fraction (>250 μm) from strata associated with MIS-16 (LU-17) indicates a Canadian source for the carbonate grains in this unit. However, statistical analysis of these grains in four cores supports the existence of a modified Beaufort Gyre circulation system existed during this period, similar to that identified by Bischof and Darby (1997).
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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 | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".