The geological history of Geysir, Iceland: a tephrochronological approach to the dating of sinter
Bibliographic record
Abstract
The vertical succession through the discharge apron of Geysir, up to 3.5 m thick, is formed of five lithological units, A–E. Units A, B, C, and E are formed of siliceous sinters whereas Unit D is a brown ash bed. Tephra grains in units C, D, and E came from Katla, Hekla, and Veiðivötn. Katla tephra in Unit D has been largely altered to palagonite. Integration of tephrochronological ages, historical records, and geological and geomorphological relationships shows that the Geysir succession developed in four main phases. During Phase I, c . 10 000–4000 years ago, laminated sinters formed from hot spring waters. Phase II, initiated c . 3300 years ago, saw the termination of sinter formation and blanketing of the area with tephra from Katla and Hekla. Phase III, c . 3000–900 years ago, represented by the boundary between units D and E, was characterized by weathering and little sinter deposition. Phase IV was initiated with the (re)birth of Geysir 800–900 years ago. Sinter deposited from the discharged waters has, however, been largely confined to the southern part of the discharge apron. Only limited opal-A precipitation has occurred since 1916 because of a decline in Geysir's eruptions.
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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 | 0.001 |
| 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".