Silver Mineralization in Deep Magmatogenic Systems of Ancient Island Arcs: The Ildeus Ultrabasic Massif, Stanovoy Mobile Belt (Russian Far East)
Bibliographic record
Abstract
Abstract The Triassic (232–233 Ma) Ildeus mafic-ultrabasic massif is a fragment of a large mineralized magmatogenic system formed within the Stanovoy Mobile Belt at the Mesozoic stage of its evolution. Ultrabasic rocks are represented by cumulative plagioclase- and amphibole-bearing dunites, peridotites, websterites, and pyroxenites; basic rocks are gabbro-anorthosites, norites, and two-pyroxene gabbro. Most intrusive rocks of the Ildeus magmatogenic system experienced ultramafic (serpentine, chlorite, talc, and carbonates) and acidic (quartz, biotite, potassium feldspar, and secondary micas) metasomatism. Geochemical characteristics (calc-alkaline differentiation trend, negative anomalies of highly-charged incoherent elements) indicate the subduction nature of the primary magma in the Ildeus system. The ultrabasic rocks are intruded by intermediate-acidic intrusions with geochemical characteristics of adakite. Magmatic-stage silver mineralization is represented by microinclusions of cuprous silver, alloys of silver, copper, gold and zinc, acanthite and silver halides in association with pentlandite, chalcopyrite, bornite, and pyrrhotite. These rocks are characterized by microinclusions of native platinum, gold, tungsten, bismuth, lead, PGE alloys, W–Co–Ti, Sb–Pb, Cu–Zn–Sn, minerals of Ag–Cu–Sb–Se–S and Zn–Ni–Co–Fe–S systems, barite, chlorapatite and Bi–Sn–Pb chlorides. At the metasomatic stage, native silver, Au–Ag alloys, silver and copper chlorides, acanthite, silver and lead tellurides coexist with, pyrite, sphalerite, galena, native nickel and gold, Cu–Zn alloys, sulfides of the Pb–As–Cu–Fe–S and bismuth chloride. At the magmatic stage, silver minerals crystallized under reducing conditions in the presence of high-temperature aqueous fluids enriched in sulfide sulfur, halogens, and volatile siderophile (W, Pt) and chalcophile (Ag, Bi, Sn, Sb, and Pb) metals that entered the primary melt from serpentinites, metamorphosed gabbroids, and metal-bearing pelagic sediments of the subducting oceanic plate. Metasomatic parageneses of silver minerals were formed under oxidized near-surface conditions with the participation of low-temperature water–salt solutions with elevated concentrations of sulfate sulfur, arsenic, and tellurium. A two-stage model is proposed for the formation of silver mineralization in the island-arc magmatic systems, where the high-temperature magmatic stage of the formation in deep crustal parts is replaced by low-temperature hydrothermal ore formation processes in near-surface conditions.
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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 | 0.002 | 0.001 |
| 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) | 0.001 | 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".