Formation of modern and Paleozoic stratiform barite at cold methane seeps on continental margins: Comment and Reply
Bibliographic record
Abstract
The proposal of Torres et al. (2003), that Paleozoic barite deposits in Nevada, Arkansas, and China formed at cold seafl oor methane seeps, is an important addition to the large literature on the genesis of bedded barite. However, we would like to point out that Torres et al. use fl awed criteria to exclude a hydrothermal origin for these and other barite deposits, and as a consequence, their larger conclusions are open to question. The diagnostic criteria set forth for hydrothermal barite are: (1) Sr that is less radiogenic than contemporaneous seawater Sr, (2) 34 S values within 2 of contemporaneous seawater sulfate, and (3) associated polymetallic sulfi de deposits. These criteria take into account spreading-ridge hydrothermal systems that can deposit barite in association with volcanogenic massive sulfi de deposits of Zn, Cu, and Pb. They do not apply to sedimentary-exhalative hydrothermal systems that can form both bedded barite deposits and the sediment-hosted massive sulfi de deposits of Zn, Pb, and Ag (barite) that account for the bulk of the world's known Zn and Pb reserves. Whereas spreading-ridge hydrothermal systems arise from seawater convection through hot volcanic rocks, sedimentary-exhalative hydrothermal systems arise from the ascent of basinal brines through sedimentary sequences into intracratonic or continental margin seas. There are barite deposits throughout the world that are clearly products of sedimentary-exhalative hydrothermal systems and show none of the criteria set forth by Torres et al. as diagnostic of a hydrothermal origin. To cite just a few examples, at Jason and Tom in western Canada, at Meggen and Rammelsberg in Germany, and at Red Dog in northwest Alaska, barite occurs both intergrown with sulfi de minerals and as barite-only deposits above or lateral to massive sulfi de bodies. At all these localities, the barite contains Sr that is more radiogenic than contemporaneous seawater Sr The barites do not show 34 S values within 2 of contemporaneous seawater sulfate, but rather can extend up to 30 higher Barite-only deposits occur not only in close association with sulfi de deposits but also far removed from them (tens of km), although commonly at the same stratigraphic horizons (e.g.,
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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".