PALEOMAGNETISM AND TECTONIC ROTATION OF THE RESTORATION POINT MEMBER OF THE BLAKELEY FORMATION (TYPE BLAKELEY STAGE), BAINBRIDGE ISLAND, WASHINGTON, AND THE PACIFIC COAST OLIGOCENE-MIOCENE BOUNDARY
Bibliographic record
Abstract
The Restoration Point Member of the Blakeley Formation, on the southeastern tip of Bainbridge Island just west of Seattle, Washington, consists of over 1500 m (4500 feet) of turbidites. Outcrops on the wave- cut platform around Restoration Point were the original basis of the late Oligocene Blakeley Stage, as well as the type section of the Echinophoria (=Liracassis) rex zone. Blakeley age rocks yield many important marine mammal fossils, especially whales. Paleomagnetic samples spanning the key fossiliferous interval of the upper 650 meters of the formation showed a stable remanence held mainly in magnetite, which exhibits a clockwise tectonic rotation of 80 ± 5°. This is as large as any rotation previously published from the region, but consistent with new data from the upper Oligocene-Miocene Pysht and Clallam formations on the northern flank of the Olympic Mountains. Except for one reversed site, the entire formation was normal in polarity. Based on its Zemorrian and Saucesian benthic foraminifera, we correlate the section with magnetic Chrons C6Cn2n to C6Cn3n (23.7-24.2 Ma), which straddles the Oligocene-Miocene boundary. This is consistent with correlations of similar strata of the Clallam Formation in the northern Olympics, and the Sooke Formation in southwestern Vancouver Island, British Columbia, Canada, suggesting that there was a widespread pulse of deposition in the region in the latest Oligocene. The magnetic polarity pattern of the formation suggests that the entire 650 m of section was rapidly deposited, and does not span the entire late Oligocene as previously suggested.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".