FLUID INCLUSIONS IN LATE-STAGE Pb Mn As Sb MINERAL ASSEMBLAGES IN THE LANGBAN DEPOSIT, BERGSLAGEN, SWEDEN
Bibliographic record
Abstract
The Långban deposit in the Paleoproterozoic Bergslagen ore province in southwestern central Sweden is well known for its complex and unique mineralogy. The largest number of exotic species occur in late-stage Pb–Mn–As–Sb-bearing fissures of disputed origin. Fluid inclusions in fissure-hosted allactite, barite, blixite, calcite, sarkinite, tilasite and finnemanite suggest a low-temperature near-surface formation at, or close to, atmospheric pressure, from aqueous NaCl–CaCl2–MgCl2 solutions of initially moderate salinity. Mineral formation started at temperatures of ca. 180°C, with the fluid evolving through reactions with Mn-oxide-bearing dolomites and a sequence of boiling events, initiated by repeated fracturing, at temperatures fluctuating between ca. 80 and 130°C. This main stage is characterized by precipitation of alternating species (e.g., barite, calcite, allactite, native lead, pyrochroite), with solutions evolving further to heterogeneous high-salinity compositions at temperatures less than ca. 70°C. Late low-salinity inclusions formed through partial condensation of the expelled vapor phase. Continued formation of minerals (e.g., arsenites, H2O-rich arsenates) after the major boiling events is characterized by temperatures decreasing well below 70°C. The solutions responsible for the specific fissure-mineralization at Långban were introduced in a very shallow post-Svecokarelian brittle tectonic environment, in conjunction with a ca. 1 Ga tectonothermal episode, or possibly coupled to post-1.8-Ga granitic magmatism. The absence of similar mineralized systems of brittle fissures on a regional scale suggests that the metals in the Långban fissures were derived very locally from the pre-existing volcanic-exhalative mineralization and not intro-
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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; both teacher heads agree on what is shown here.
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".