Last interglacial sea-level history from speleothems: a global standardized database
Bibliographic record
Abstract
Abstract. Speleothems (secondary cave carbonate precipitates) are archives of valuable information for reconstructing past sea levels as they are generally protected from weathering and erosion by their location and can be dated with U-series methods. Two main categories of speleothems are recognized as sea-level indicators: phreatic overgrowth on speleothems (POSs) and submerged vadose speleothems (SVSs). POSs have the great advantage that they precipitate on preexisting supports (vadose speleothems or cave walls) at a brackish water level equivalent to sea level when air-filled chambers of coastal caves are flooded by rising sea. SVSs are also useful, but sea level is inferred indirectly as periods of growth provide constraints on maximum sea-level positions, whereas growth hiatuses, sometimes difficult to observe, may indicate times when cave passages are submerged by sea highstands; hence they record minimum sea-level elevations. Here we describe a compilation that summarizes the current knowledge of the complete last interglacial (in its broadest sense from ∼ 140 to 70 ka, also known as marine isotope stage (MIS) 5) sea level captured by speleothems. We used the framework of the World Atlas of Last Interglacial Shorelines (WALIS), a comprehensive sea-level database, to provide a standardized format in order to facilitate scientific research on MIS 5 sea level. The discussion is focused on MIS 5e, but records that capture MIS 5d, 5c, 5b, and 5a are also included. We present the data from 71 speleothems (36 sea-level index points and 37 limiting points) in coastal caves located in 10 different locations, and we include the spatial coverage, the samples used, and their accuracy as indicators of sea level, U and Th isotopes used to generate the chronologies, and their scientific relevance to understand past sea-level changes. Furthermore, the paper emphasizes the usefulness of these indicators not only to render information regarding the eustatic sea level, but also for their contribution to refine the glacial isostatic adjustment models and to constrain regional tectonic uplift rates. The standardized sea-level database presented here is the first of its kind derived from speleothems and contains all the information needed to assess paleo relative sea levels and the chronological constraints associated with them. The database is available open-access at https://doi.org/10.5281/zenodo.4313860 (Dumitru et al., 2020). We refer the readers to the official documentation of the WALIS database at https://walis-help.readthedocs.io/en/latest/ (last access: 20 January 2021), where the meaning of each field is explained in detail.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.014 | 0.018 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 0.004 |
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".