Distinguishing Glacial AMOC and Interglacial Non‐AMOC Nd Isotopic Signals in the Deep Western Atlantic Over the Last 1 Myr
Bibliographic record
Abstract
Abstract The global thermohaline circulation plays a major role in regulating global climate, driven by the formation of North Atlantic Deep Water (NADW) . ODP Site 1063 on the Bermuda Rise, at the interface of NADW and Southern Ocean‐sourced water, appears an ideal location to study the relationships between ocean circulation and climate. This study reports Nd isotope ratios at Site 1063 that extend to ~1 Ma. The data show Nd isotope values during portions of interglacials that are much lower than modern NADW. However, interglacial Nd isotope values at Site 607, located within the core of NADW, off the abyssal seafloor in the North Atlantic, are consistently similar to modern NADW. In contrast to glacial values, we infer that interglacial Nd isotopes at Site 1063 are not representative of NADW and do not solely record water mass mixing. We conclude that the low Ndisotope ratios reflect regional particle‐seawater exchange as a consequence of input of freshly ground bedrock from the Canadian shield, which is eroded into the North Atlantic during major ice sheet retreats. The result is a deep, thin, and regionally constrained layer of seawater tagged with this anomalous low Nd isotope signature that is unrepresentative of the Atlantic Meridional Overturning Circulation (AMOC) . We suggest that a benthic nepheloid layer, whose development is linked to the behavior of a deep‐recirculating gyre system, regulated by the interaction between the Gulf Stream and the deep western boundary current, facilitates the periodic masking of the Nd isotope signature of the North Atlantic AMOC end‐member in this region at these depths.
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 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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".