Bibliographic record
Abstract
Impact cratering is widespread in the Solar System and involves extremely high pressures and temperatures. The physical and chemical reactions during an impact are far from equilibrium, but the extreme conditions will not apply to all the target materials involved in the impact. This gives rise to disordered material next to highly crystalline and shock metamorphosed material. The aim of this study is to attain a better understanding of the fate of carbon and the degree of preservation of organic matter in impact craters. This topic is relevant to prebiotic chemistry, planetary exploration and panspermia. Three natural impact craters were investigated: The Eocene Haughton impact structure on Devon Island in the Canadian High Arctic, where the target is composed of a thick sedimentary sequence with pre-impact hydrocarbons, the Ordovician Lockne impact structure in central Sweden, where organic- and uranium-rich Alum Shale is present in the target, and the PreCaledonian Gardnos impact structure in south-central Norway, also with carbon-rich shales in the target. An analogue example of rapid heating of organic matter by igneous intrusion in carbonrich rock, and an experimental hypervelocity impact in a carbon-rich rock were also studied. In the Haughton impact crater, fossil biological markers are preserved within lithic clasts in the impact melt breccia. Fossil biological markers are also preserved in the experimental impact crater, and in the material excavated during the experimental impact. Instantaneous melting and quenching in the Gardnos suevite (impact melt rock) has caused the incorporation of disordered carbon in the suevite melt. In the Haughton impact melt breccias, around 20% total organic carbon is preserved after impact, and in the Gardnos impact crater, at least 38% of the original carbon is preserved in a disordered form. In the Lockne impact crater, carbon is particularly preserved by polymerisation around radioactive minerals. This study shows that organic matter does not necessarily oxidise or change in to highly crystalline forms during an impact event, but that substantial amounts can be preserved in a disordered form.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 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".