Late Pleistocene East Asian monsoon intensity variations and driving mechanisms: Evidence from a multi-proxy analysis of loess deposits on an East China Sea island
Bibliographic record
Abstract
Shengshan Island (SSD), located in East China Sea, contains loess deposits that serve as an excellent carrier for recording environmental changes in the eastern subtropical region of China. Different from the continental Loess Plateau, SSD loess possesses distinctive characteristics due to its coastal location. Here we conducted the first pollen analysis to reconstruct vegetation dynamics in the SSD region during the middle to late Late Pleistocene period (75-40 ka). Biological indicators (i.e., total organic concentration and δ13Corg), along with geochemical proxies (i.e., quartz grain size, magnetic susceptibility, iron oxide ratios, clay minerals, and trace elements), were employed to reconstruct climatic dynamics in the SSD area. The study identified two stages in the evolution of the East Asian Monsoon. In Stage I (75-60 ka), various indicators (i.e., pollen concentration, Pinus concentration, magnetic susceptibility, C4 abundance, K/(I+Ch), Illite crystallinity, CII, Hm/Gt, quartz median grain size, Zr/Rb) increased, suggesting a strengthening of both winter and summer monsoons. In Stage II (60-40 ka), some indicators (i.e., pollen concentration, Pinus concentration, quartz median grain size, Zr/Rb) continued to increase while others (i.e., magnetic susceptibility, C4 abundance, K/(I+Ch), Illite crystallinity, CII, Hm/Gt) decreased, indicating a continued intensification of the winter monsoon but a weakening of the summer monsoon. Further, we explored the driving forces behind variations in monsoon intensity, analyzing changes in various δ18O proxies and sea-level fluctuations. The findings suggest that different mechanisms influence the winter and summer monsoons. Summer monsoon intensity is linked to changes in summer solar radiation at mid-latitudes in the Northern Hemisphere, while winter monsoon dynamic is affected by changes in ice volume and ice sheets. These insights contribute to our understanding of environmental changes related to the East Asian Monsoon, offering valuable perspectives on how these mechanisms could respond to future climate changes.
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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 | 0.001 |
| 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".