Fish tooth U-Pb dating reveals the late Miocene REY enrichment of the Clarion-Clipperton Fracture Zone
Bibliographic record
Abstract
Abstract Deep-sea sediments enriched in rare earth elements and yttrium (REY) are promising mineral resources and are extensively developed in the Pacific Ocean. However, REY enrichment mechanisms of deep-sea sediments remain poorly constrained due to a lack of chronological constraints on associated geological events. We integrated bioapatite U-Pb geochronometry with geochemical data to elucidate the temporal evolution and genetic processes of REY-rich sediments located in the Clarion-Clipperton Fracture Zone (CCFZ) in the central North Pacific Ocean. Fish tooth specimens, separated from deep-sea sediments collected from core MG026, were subjected to in situ trace-element analysis and U-Pb dating on their enamel-protected dentin layers using laser ablation–inductively coupled plasma–mass spectrometry. The bioapatite samples exhibited higher enrichments in total REY (ΣREY) and uranium than bulk sediments, and a moderate positive correlation between ΣREY and uranium concentrations. These bioapatite samples yielded Tera-Wasserburg lower intercept ages ranging from 15.8 ± 1.2 Ma to 9.5 ± 1.4 Ma, robustly constraining the depositional age of the host sediments and revealing a pronounced REY enrichment episode from 12.0 Ma to 9.0 Ma. Our results demonstrate a mean sedimentation rate of ~0.48 m/m.y. for the REY-rich sediments in the CCFZ. Multivariate analysis of bulk geochemical data indicates that REY-enrichment in CCFZ sediments is controlled not only by slow deposition rate but also by REY-bearing mineral phases and depositional environment conditions (including redox conditions and biological productivity). The REY enrichment event (ca. 12.0–9.0 Ma) is characterized by a significant transition toward more oxygenated and higher productivity conditions, as documented by trace metal enrichment factors (EF) of MoEF, UEF, CuEF, and NiEF. This event coincided with the progressive closure of the Central American Seaway, which enhanced the advection of oxygen-enriched, nutrient-bearing bottom waters into the CCFZ, promoting extensive formation of Fe-Mn (oxyhydr)oxides and facilitating REY enrichment. Our study establishes a reliable geochronological framework for late Miocene REY enrichment and provides exploration strategies linking tectonic events to deep-sea REY mineralization in the CCFZ.
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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 | 0.000 |
| 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) | 0.002 | 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".