Rinkite-(Ce) in the nepheline syenite pegmatite from the Saima alkaline complex, northeastern China: Its occurrence, alteration, and implications for REE mineralization
Bibliographic record
Abstract
Abstract The nepheline syenite pegmatite in the Saima alkaline complex in northeastern China is characterized by REE mineralization, mainly rinkite-(Ce) and associated alteration minerals. As the most abundant REE-bearing mineral in the pegmatite, rinkite-(Ce) closely coexists with microcline, nepheline, natrolite, and calcite. Some rinkite-(Ce) grains show compositional sector-zonation, in which the inner core displays relatively high Ti, Ca, and Sr concentrations, but low Zr, REE, and Na contents. Primary rinkite-(Ce) has undergone multiple episodes of fluid interactions, and accordingly, from weak to strong, three different mineral assemblages of hydrothermal alteration can be summarized: (1) rinkite-(Ce) + secondary natrolite ± K-feldspar ± minor fluorbritholite-(Ce); (2) rinkite-(Ce) relics + secondary natrolite + K-feldspar + fluorbritholite-(Ce) + unidentified Ca-Ti silicate mineral + fluorite and calcite; and (3) pseudomorphs after rinkite-(Ce). The pseudomorphs can be divided into two groups characterized by distinct mineral associations: (1) Ca-bearing strontianite + fluorbritholite-(Ce) + natrolite + fluorite + calcite coexisting with silicate minerals; and (2) calcite + fluorite + fluorbritholite-(Ce) + rinkite-(Ce) relics ± Ca-bearing strontianite ± ancylite-(Ce) associated with a calcite matrix. These alteration mineral assemblages are evidence of magmatic-derived alkali metasomatism due to an alkali-CO2-F-rich fluid and Ca-metasomatism due to a different, externally derived Sr- and Ca-rich fluid. The metasomatic events acted as the potential driving force for the rinkite-(Ce) dissolution and pseudomorph-forming process. The high concentration of rinkite-(Ce) in the nepheline syenite pegmatite results from the fractional crystallization of the Saima CO2-rich alkaline silicate magma, and the successive alterations of rinkite-(Ce) attest to the important role played by hydrothermal fluids in controlling the remobilization of REE and the crystallization of secondary rare earth minerals.
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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) | 0.000 | 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 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".