两万年来的中国多年冻土形成演化
Bibliographic record
Abstract
利用大量的古多年冻土遗迹和古冰缘现象, 并佐以古冰川、孢粉及动物化石等资料, 重建了20ka以来中国多年冻土演化进程. 结果表明, 在末次冰期最盛期(LGM, 或末次多年冻土最大期LPMax), 中国多年冻土面积达到了5.3<x content-type="symbol">´</x>10<sup>6</sup><x content-type="symbol">~</x>5.4<x content-type="symbol">´</x>10<sup>6</sup>km<sup>2</sup>(现今中国多年冻土面积的3倍多), 而全新世大暖期(HMP, 或末次多年冻土最小期LPMin), 中国多年冻土面积曾缩减至0.80<x content-type="symbol">´</x>10<sup>6</sup><x content-type="symbol">~</x>0.85<x content-type="symbol">´</x>10<sup>6</sup>km<sup>2</sup>(约为现今中国多年冻土面积的50%). 按照古冻土遗迹的年代及分布等特征, 在确定LGM和HMP两个主要时段的冻土格局基础上, 将20ka以来中国多年冻土演化进程划分为7个阶段: 晚更新世LGM(20000<x content-type="symbol">~</x>10800aBP)多年冻土强烈扩展, 达到LPMax; 早全新世气候剧变期(10800至8500~7000aBP)多年冻土较稳定但相对缩减阶段; 中全新世HMP(8500~7000至4000~3000aBP)多年冻土强烈退化阶段, 多年冻土缩减到LPMin; 晚全新世新冰期(4000~3000至1000aBP)冻土扩展阶段; 晚全新世中世纪暖期(1000<x content-type="symbol">~</x>500aBP)多年冻土相对退化阶段; 晚全新世小冰期(LIA, 500<x content-type="symbol">~</x>100aBP)冻土相对扩展阶段, 以及近代升温期(近百年来)多年冻土持续退化阶段. 本文重建了各时段内古气候、古地理环境以及多年冻土分布范围和其他特征.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.005 | 0.005 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.033 | 0.016 |
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".