Evaluating the O‐Cr‐Mo isotope signatures in various meteorites representing core–mantle–crust fragments: Implications for partially differentiated planetesimal(s) accreted in the early outer solar system
Bibliographic record
Abstract
Abstract The Allende, Eagle Station pallasites (ESP), some ungrouped achondrites (UA), and ungrouped irons (UI) represent different types of meteorites; these are traditionally distinguished as chondrule‐bearing chondrite, chondrule‐free stony irons, stones, and irons, respectively. Oxygen isotopic compositions of meteorites have long been used as a robust tool to identify the parent bodies of these extraterrestrial materials. We revisited the δ 18 O‐∆ 17 O, along with ε 54 Cr and ε 92 Mo, of these meteorites and established a genetic link that possibly suggests that undifferentiated carbonaceous chondrites and their differentiated counterparts belong to a common reservoir. We observed that the differentiated counterparts of Allende CV3 including ESP, ungrouped achondrites, and ungrouped irons collectively provide the oxygen isotope trends comparable to those of the Y&R and the PCM lines, and are likely to represent the primitive isotope reservoirs in the solar nebula. ε 54 Cr and ε 92 Mo data of these meteorite types support their oxygen isotope trends. The idea of a common partially differentiated parent body also lends support from natural remnant magnetization in the CV chondrites and Eagle Station olivine. Furthermore, ∆ 17 O‐ε 54 Cr data suggest that these meteorites originated from carbonaceous planetesimal(s) accreted at different heliocentric distances in the solar nebula in the outer solar system. As proposed earlier, these bodies remained separated from the inner solar system due to formation of Jupiter. Taken together, we propose that the ungrouped irons, ESP, and ungrouped achondrites could possibly represent the differentiated sections, such as core, core–mantle, and mantle of a planetesimal(s), respectively, with the Allende CV3 representing an undifferentiated chondritic crust.
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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 | 0.002 | 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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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 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".