Eclogite xenoliths from the Chidliak kimberlite, Baffin Island, Nunavut, Canada
Bibliographic record
Abstract
I studied the petrography, major element chemistry, geothermobarometry, and trace element chemistry of 19 eclogite xenoliths from Chidliak kimberlites (Baffin Island, Nunavut, Canada). These granoblastic, partially melted, mostly bi-mineralic eclogites are composed of pyrope and omphacite, with accessory orthopyroxene, kyanite, and rutile, as well as secondary chlorite, serpentine, phlogopite, amphibole, and spinel. The Chidliak eclogites are classified in the Coleman’s groups A, B, and C based on the garnet composition, and into groups A and B based on the clinopyroxene composition. Parameters of the eclogite formation were calculated by projecting clinopyroxene-garnet temperatures onto a geotherm constrained using Chidliak peridotite xenoliths. Thermobarometry of Chidliak eclogites yields temperatures of 855-1390°C and pressures of 45 70 kbar, i.e. in the diamond stability field. The temperatures may have been overestimated by 50-120°C due to the inability to account for Fe³⁺ in clinopyroxene and garnet. Chidliak eclogites come from the depths similar to those for eclogites of the Slave craton. Whole rock major and trace element composition was reconstructed based on the compositions of clinopyroxene, garnet, and accessory minerals analyzed on the electron microprobe and laser ablation inductively coupled plasma mass spectrometer. Whole rock major element composition of the eclogites suggests that their protoliths could be Archean basalts or oceanic gabbros, modified by partial melting and carbonatitic mantle metasomatism. Metasomatism was responsible for the introduction of Mg into Chidliak eclogites with MgO>16.5 wt. % and the high Zr/Hf values that correlate with the high MgO bulk content. Based on REE and HFSE concentrations, Chidliak eclogites were divided into several groups that show evidence for: 1) the origin in a shallow, low-P, garnet-free source protolith, 2) partial melting and extraction of arc melts, 3) cumulation of plagioclase, and 4) ancient mantle metasomatism by alkali and carbonatitic fluids. I propose two possible tectonic settings for the formation of the studied eclogites: 1) metamorphosed mid-ocean ridge gabbros subducted under the Hall Peninsula Block during the 1.8-1.9 Ga Trans-Hudson orogeny, or alternatively 2) oceanic plateau basalts metamorphosed to Archean greenstone belts of the North Atlantic Craton that sank to the mantle via delamination of the lower crust.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.003 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".