Nonporphyritic chondrules and chondrule fragments in enstatite chondrites: Insights into their origin and secondary processing
Why this work is in the frame
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Bibliographic record
Abstract
Abstract Sixteen nonporphyritic chondrules and chondrule fragments were studied in polished thin and thick sections in two enstatite chondrites ( EC s): twelve objects from unequilibrated EH 3 Sahara 97158 and four objects from equilibrated EH 4 Indarch. Bulk major element analyses, obtained with electron microprobe analysis ( EMPA ) and analytical scanning electron microscopy ( ASEM ), as well as bulk lithophile trace element analyses, determined by laser ablation inductively coupled plasma–mass spectrometry ( LA ‐ ICP ‐ MS ), show that volatile components (K 2 O + Na 2 O versus Al 2 O 3 ) scatter roughly around the CI line, indicating equilibration with the chondritic reservoir. All lithophile trace element abundances in the chondrules from Sahara 97158 and Indarch are within the range of previous analyses of nonporphyritic chondrules in unequilibrated ordinary chondrites ( UOC s). The unfractionated (solar‐like) Yb/Ce ratio of the studied objects and the mostly unfractionated refractory lithophile trace element ( RLTE ) abundance patterns indicate an origin by direct condensation. However, the objects possess subchondritic CaO/Al 2 O 3 ratios; superchondritic (Sahara 97158) and subchondritic (Indarch) Yb/Sc ratios; and chondritic‐normalized deficits in Nb, Ti, V, and Mn relative to RLTE s. This suggests a unique nebular process for the origin of these EC s, involving elemental fractionation of the solar gas by the removal of oldhamite, niningerite, and/or another phase prior to chondrule condensation. A layered chondrule in Sahara 97158 is strongly depleted in Nb in the core compared to the rim, suggesting that the solar gas was heterogeneous on the time scales of chondrule formation. Late stage metasomatic events produced the compositional diversity of the studied objects by addition of moderately volatile and volatile elements. In the equilibrated Indarch chondrules, this late process has been further disturbed, possibly by a postaccretional process (diffusion?) that preferentially mobilized Rb with respect to Cs in the studied objects.
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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 | 0.000 | 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 | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| 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 it