Using paleomagnetism to unravel the mysteries of the Summit Creek Basalts
Bibliographic record
Abstract
The Summit Creek Basalts are a sequence of steeply dipping subaerial late Eocene basaltic flows located southeast of Washington’s Mount Rainier. Despite previous petrologic and paleomagnetic investigations, the origins of these basalts are poorly understood. It is uncertain whether they erupted in situ or were transported to their present location by tectonic processes. It is possible that these lavas were derived from the same magma source as a sequence of flows in the Crescent Formation on the Olympic Peninsula, as both erupted between 45 and 50 million years ago and have similar chemical compositions. A new paleomagnetic analysis of the orientation of the magnetic field recorded in the Summit Creek Basalts was conducted to provide evidence for any rotation or north-south motion that has occurred since the flows erupted. Over a dozen flows were sampled along Highway 12 and Carleton Ridge in May and June of 2014. The basalt cores were analyzed with a Molspin spinner magnetometer using standard alternating field demagnetization and thermal demagnetization. These methods determined the thermal remnant magnetization of the flows and clues to the types of magnetic minerals in the basalt. Structural features were also mapped to provide further insight into the stresses that shaped the unit. It was found that the flows had been rotated an average of 45 degrees counterclockwise, tilted, and deformed by tectonic stresses, which indicate that they have been moved from their original location.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".