The sedimentary structure between the Mendeleev and Lomonosov ridges, Arctic Ocean
Bibliographic record
Abstract
During the RV Polarstern cruise ARK-XXIII-3 in summer of 2008, geophysical data of a nearly 1200 km long seismic transect along 81° N including the Amundsen Basin, Lomonosov Ridge, Makarov Basin, Mendeleev Ridge and Canada Basin could be acquired. The objective was to understand the tectonic evolution of the Makarov Basin in relation to the evolution of the adjacent Lomonosov and Mendeleev ridges in the Amerasia Basin.The data acquisition involved seismic reflection and refraction data, gravity, bathymetry, and magnetics. The seismic survey set-up included a 300 m streamer and a 32 liter airgun cluster. Because of ice conditions, gaps remained between the profiles but for the first time it was possible to get a nearly complete overview over the three main features within the Arctic Ocean. In addition to reflection seismic data, eight sonobuoys were deployed along the profiles to better resolve the seismic velocities in the sedimentary column.The seismic sections are dominated by an unconformity that persists across the entire transect and that separates the flat-lying well-stratified upper unit of Cenozoic age from the lower Mesozoic sediment sequences, which are dominated by pervasive normal faulting. The unconformity marks the break-up of the Lomonosov Ridge from the Siberian/Barents shelves between 56-65 Ma ago.The developed velocity depth functions indicate sediment thicknesses from 1200-2000 m on the Lomonosov Ridge to 5500-6300 m within the deepest point of the Makarov Basin around 168° E, to 1000-1500 m on the western flank of the Mendeleev Ridge, to ~ 4000 m within the Canada Basin.The continental origin of the Lomonosov Ridge could be approved. The fact that evidences for oceanic origin are missing leads to the assumption that the Makarov Basin is created only by extension of continental crust between the opening of the Canada Basin and the initiation of the Eurasia Basin, 120 - 56 Ma ago. However, the possibility of a partly oceanic crust can not be ruled out.The high velocities of the basement (> 6.4 km/s), the density characteristics and the uniform crust within the 2D gravity modeling leads to the conclusion that the Mendeleev ridge has an oceanic origin. The modeled thick crust (33 km) could be explained by the theory of a Large Igneous Province (LIP) around 89 Ma ago.All interpretations support the rotational models.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.004 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| 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 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".