Preservation of igneous and metamorphic charnockites in the Paleoproterozoic Prøven Igneous Complex, Rinkian Orogen, central West Greenland
Bibliographic record
Abstract
• Prøven igneous complex preserves igneous and metamorphic charnockites. • Emplacement occurred at relatively shallow crustal levels. • Magmatism was accompanied by high-grade metamorphism. • Related to the collision of the Meta Incognita microcontinent and the Rae Craton. The Paleoproterozoic Prøven Igneous Complex (PIC) of the Rinkian Orogen in central West Greenland comprises a suite of arc-related charnockite plutons, extending over an area of at least 7200 km 2 . The PIC was emplaced into paragneisses of the Karrat Group during a series of magmatic events between c. 1900 and 1850 Ma. Magmatism was accompanied by high-grade metamorphism and deformation, culminating in granulite facies peak conditions and partial melting at c. 1820 Ma. To unravel the conditions of charnockite formation and granulite facies metamorphism, a detailed petrographic study was carried out on samples from the PIC and the surrounding paragneisses. The rock types studied include i) charnockites from the massive PIC, ii) charnockites and migmatites from the layered lower PIC, iii) migmatites from the surrounding paragneisses, and iv) igneous enclaves from the lower PIC. Charnockites from the massive PIC generally show a magmatic, porphyritic texture and only minor macro-textural evidence of deformation. The lower PIC and paragneisses are both migmatized and exhibit extensive recrystallization with a solid-state crystal-plastic fabric. Igneous enclaves are found within the lower PIC and show an equigranular, igneous texture. Based on the dominant igneous texture it is interpreted that the massive PIC crystallized from a dry magma and was not significantly overprinted during peak metamorphism. Phase equilibrium modelling, Hb-Pl thermometry and Al-in-hornblende barometry constrain the PIC to have been emplaced at 680–795 °C and 4.2–5.4 kbar. By contrast, the lower PIC and paragneiss samples record granulite facies peak conditions of 785–805 °C and 3.4–4.0 kbar, suggesting that both charnockite magmatism and metamorphism took place at relatively shallow crustal levels. Our results are consistent with the P-T conditions recorded by the 1890–1880 Ma Qikiqtarjuaq Plutonic Suite, an arc-type charnockite intrusion on Baffin Island, Canada. A correlation between the tectonothermal events on Baffin Island and in the Rinkian Orogen is proposed, therefore relating the intrusion of the PIC to the collision of the Meta Incognita microcontinent and the Rae Craton.
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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 | 0.000 | 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) | 0.003 | 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".