S30. New Developments in Quaternary Numeric Dating Methods
Bibliographic record
Abstract
Chronologies from ice cores are one of the most important benchmarks for Quaternary dating up to 100 ka. In addition to being used to define the timing of specific events such as the Younger Dyras termination, the GISP2 ice core in particular has been critical for radiocarbon calibration prior to 10 ka, since its provides the basis of the chronology of the Cariaco basin varve sequence. Furthermore, paleoclimate records from ice cores, due to their high resolution and the general agreement that they are representative of climate over broad areas, are frequently used as benchmarks for the interpretation of other Quaternary records as far back as 400 ka. For all of these reasons, it is important that uncertainties in ice core chronologies be well understood and, where possible, improved upon. In this talk, I will briefly review the layer-counting method used to develop the most widely-used benchmark ice core chronologies – GISP2 and GRIP in central Greenland – the trace-gas-matching technique used to transfer these chronologies to cores in Antarctica, and published estimates of the uncertainties. I will then discuss possible improvements to the latter chronologies, based on the requirement of self-consistency among time series of ice accumulation rate, temperature and the difference between gas age and ice age (\\delta age). Finally, I will highlight our recent work on an ice core from Mt. Logan, Yukon, which demonstrates the reliability of the chronology of this particular core at the sub-annual timescale.
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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 | 0.006 | 0.017 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.004 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.003 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.020 | 0.013 |
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".