Physical property measurements: ICDP boreholes LB‐07A and LB‐08A, Lake Bosumtwi impact structure, Ghana
Bibliographic record
Abstract
Abstract— Physical rock property measurements provide the primary constraints for any geological models hypothesized from geophysical observations. Previous geophysical models of the Bosumtwi impact structure hypothesized that a highly magnetic and dense impact‐melt sheet might be the source of the observed magnetic anomalies. However, magnetic susceptibility and density measurements made on International Continental Scientific Drilling Program (ICDP) cores LB‐07A and LB‐08A from the interior of the Bosumtwi meteorite impact structure contain no evidence for that. Both density and magnetic susceptibility logs on both boreholes exhibit low‐amplitude contrasts between the uppermost polymict lithic breccia and suevite, the intermediate monomict lithic breccia, and the lowermost bedrock. The depth extent of fracture‐related density reduction is much greater at LB‐08A than at LB‐07A. A total magnetic intensity log from borehole LB‐08A supports the suggestion that magnetic anomalies over Lake Bosumtwi are mainly sourced in undetected and/or covered bedrock intrusions, like the ones outcropping at the northeast and to the southwest of the lake.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".