Origin of Enigmatic Structures: Field and Geochemical Investigation of Columnar Joints in Sandstones, Island of Bute, Scotland
Bibliographic record
Abstract
Columnar joints, resembling those in igneous rocks, are present in Devonian and Early Carboniferous sandstones at two localities on the Island of Bute in southwestern Scotland. New data concerning field relations and geochemical changes constrain processes responsible for generation of columnar fracture patterns in sedimentary rocks. The columns are mostly normal to bedding and occur at several discrete stratigraphic levels. The host rocks are cut by Early Carboniferous volcanic necks or plugs, which acted as heat sources, but development of columnar jointing was strongly controlled by small sills and dikes of a recessive, purple, fine-grained rock. Geochemistry of these rocks points to an igneous origin. Where contacts are exposed, columnar joints appear above subconcordant intrusions and disappear upward. The lowest parts of the columnar-jointed sandstones are Si depleted and enriched in Ca, Mg, Fe, Al, rare earth elements (REEs), and some base metals. REE patterns from columnar-jointed sandstones near contacts with intrusions resemble those of the igneous rocks, probably as a result of hydrothermal activity. Because most of the columns are approximately normal to bedding, intrusion probably took place before folding of the host rocks and possibly before complete consolidation.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".