Thallium isotope ratios record a transition to melting of hydrated oceanic crust at the Hadean-Archean boundary
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Earth's oldest continental crust is found in cratonic nuclei comprised of tonalite-trondhjemite-granodiorites (TTGs). However, the nature of the source materials that formed TTGs, as well as the timing and mechanisms of its formation remain controversial. The two endmember tectonic models for the formation of Archean TTGs are (i) vertical subduction and partial melting of the subducting hydrated oceanic crust, (ii) partial melting at the base of plume-generated oceanic plateaux [1, 2]. The thallium stable isotope composition of magmatic rocks can identify distinct components in modern subduction zone settings ( 205 Tl of primitive mantle = -2, altered oceanic crust = -2 to -16; [3]) and thus can be exploited to address early continental crust formation. Here we report Tl isotope compositions for rocks from the Acasta Gneiss Complex (AGC) in Canada, which contains the oldest known evolved crust, with igneous crystallization ages ranging from 4.03 to 2.95 Gyr [4]. Orthogneisses of the AGC have 205 Tl values in the range of -3.1 0.2 to -1.1 0.4, where lower values are consistent with the mixing of mantle melts and hydrothermally altered, hydrated oceanic 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.
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 | 0.000 |
| 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 | 0.001 |
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