The Magmatic–Hydrothermal Transition in Lithium Pegmatites: Petrographic and Geochemical Characteristics of Pegmatites from the Kamativi Area, Zimbabwe
Bibliographic record
Abstract
ABSTRACT Lithium is a critical metal, vital for electrification of transport. Currently, around half the world's lithium is extracted from rare-metal pegmatites and understanding the genesis and evolution of these igneous rocks is therefore essential. This paper focuses on the pegmatites in the Kamativi region of Zimbabwe. A group of early pegmatites is distinguished from a late pegmatite suite which includes the ca. 1030 Ma Main Kamativi Pegmatite. Previously mined for tin, the mine tailings are now being investigated for lithium. Mineral-scale investigation of samples from the Main Kamativi Pegmatite has allowed recognition of a four-stage paragenesis: (1) an early magmatic assemblage dominated by quartz, alkali feldspar, spodumene (LiAlSi2O6) and montebrasite [LiAl(PO4)(OH, F)]; (2) partial alteration by widespread albitization, associated with growth of cassiterite and columbite group minerals; (3) irregular development of a quartz, muscovite, columbite group mineral assemblage; and (4) widespread low-temperature fluid-induced alteration of earlier phases to cookeite, sericite, analcime, and apatite. Whole-rock geochemistry indicates that the late pegmatites are enriched in Li, Cs, Ta, Sn, and Rb but depleted in Nb, Zr, Ba, Sr, and the rare earth elements relative to early pegmatites and country rock granitoids. A combination of field relationships and published dating indicates that the granitoids, and probably the early pegmatites, were emplaced toward the end of the ca. 2000 Ma Magondi Orogeny, whereas the late pegmatites are almost 1000 million years younger. The late pegmatites thus cannot be genetically related to the granitoids and are instead likely to have formed by partial melting of metasedimentary source rocks. The drivers for this melting may be related to crustal thickening along the northern margin of the Kalahari Craton during the assembly of Rodinia.
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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 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".