Geological structure and perspectives for mineralization of the Kichany structure, Tiksheozersky greenstone belt (Northern Karelia)
Bibliographic record
Abstract
Mineral deposits in the Neoarchean greenstone belts in the Fennoscandian Shield, especially in its eastern (Russian) part, are not as numerous as in Archean belts of Canada, Australia, or Southern Africa. The goal of the present paper is to show with an example of Tiksheozersky belt, that Neoarchean greenstone belts in Northern Karelia and Kola Peninsula do contain ore occurrences, typical to greenstone belts in the world, therefore prospects of these geological structures for mineral deposits are not uncovered fully. Ore occurrences of jaspilite, massive sulfide pirrhotite ore, molybdenite with uranium and graphite, arsenopyrite, and gold were found in the Kichany structure of the Tiksheozersky belt. Jaspilites and massive sulfide ores were considered as syngenetic to volcanic-sedimentary host rocks. Occurrences of molybdenite, arsenopyrite, and gold are epigenetic, controlled by zones of alteration. Zonality in ore-bearing altered rocks, peculiar properties of their chemical and mineral composition, as well as composition of rock-forming and ore minerals, were studied in detail. Age of processes of alteration was estimated with different geochronological methods. Dating of zircon grains from the molybdenite occurrence with LA-ICP-MS method showed two events 2600-2700 Ma (formation of host rocks) and 2100-1900 Ma (regional metamorphism) in their formation. Estimation of age of quartz-garnet-tourmaline metasomatite from arsenopyrite occurrence with composition of monazite gave 1789 ± 47 Ma, it corresponds to post-metamorphic event, probably connected with intrusions of tourmaline granites. Gold mineralization in quartz metasomatite and skarnoid has near the same age: titanite, which contains inclusions of gold, formed 1739 ± 15 Ma ago. Hence, occurrences of gold, arsenopyrite, and molybdenite formed in Neoarchean rocks during Palaeproterozoic (Svecofennian) metamorphic-metasomatic events. Gold mineralization is the most promising in the belt. Position of gold occurrences is controlled by thrust zones, gold concentrates in altered amphibolite with arsenopyrite-pirrhotite mineralization.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".