The ice-covered Aurora hydrothermal vent field, Gakkel Ridge, Arctic Ocean: ultramafic-influenced venting at a mafic axial volcano on Earth’s slowest spreading center
Bibliographic record
Abstract
• First detailed geological exploration and sampling of an Arctic Ocean vent field. • Aurora sulfide chimneys are thin-walled with primarily high-temperature mineralogy. • Chimney compositions indicate subsurface fluid interaction with ultramafic substrate. The Aurora vent field, located on Gakkel Ridge, Earth’s slowest spreading mid-ocean ridge, is covered by perennial Arctic sea ice. Previous expeditions briefly glimpsed active venting near an axial volcano summit, but challenges of operating in drifting sea ice prevented detailed exploration and sampling. During the 2021 HACON expedition, Aurora was extensively imaged and sampled with a remotely operated vehicle adapted to these conditions, marking the first successful geological exploration of hydrothermal vents under ice. We present results of visual surveys and mineralogical and geochemical analyses of rocks and fluids collected at Aurora in the context of hydrothermal deposits in ultraslow settings. Active black smokers (350–356 °C) and extinct partially buried chimneys were documented over mafic lava flows covered in up to ∼5 m of sediment. Venting of extremely H 2 -rich (near 0.05 M) and Si-poor acidic fluids forms chimneys dominated by high-temperature minerals (anhydrite, isocubanite, chalcopyrite, pyrrhotite, magnetite, bornite). The chimneys are unusually thin-walled and friable, and mostly lack moderate-to-lower-temperature minerals typical of seafloor hydrothermal deposits. Minor pentlandite, elevated Ni and Co, and low Si collectively support putative subsurface interactions of hydrothermal fluids with ultramafic substrate, despite no such lithologies observed at the seafloor. Inactive chimneys are unusually coated with calcite, which may impact long-term deposit preservation. This study highlights the increasing accessibility of ice-covered Arctic Ocean seafloor for geological investigations. The results will inform future exploration on Gakkel Ridge, serving as an ultraslow-spreading endmember against which to compare yet undiscovered vent fields along this largely unexplored ridge.
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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 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| 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".