Structural Evolution of the Northern Agrio Fold and Trust Belt (∼37°30′S), Neuquén Basin, Argentina, Derived From Low‐Temperature Multi‐Thermochronometry
Bibliographic record
Abstract
Abstract The Agrio Fold and Thrust Belt (FTB), situated in the Southern Central Andes at 37–39°S, underwent two phases of contractional deformation: Late Cretaceous‐Eocene and middle‐late Miocene. Despite advances in understanding its tectonic history, many questions persist regarding the timing and activity of specific structures during these deformation phases. By combining low‐temperature multi‐thermochronometry, inverse thermal models and field structural data, we present a new thermal‐structural history for the northern Agrio FTB. Our findings unveil an initial cooling event between approximately 85–75 Ma and 55–50 Ma, involving cooling rates of 1.1–2°C/Ma and vertical displacement rates from 0.07 to 0.12 km/Ma. This slow event, confined to the inner zone, is associated with the growth of the basement‐cored Manzano anticline. Additionally, still in the inner zone of the Agrio FTB, a second and faster cooling event from ∼15–10 Ma to 0 Ma, marked by a cooling rate of 7°C/Ma and a vertical displacement rate ranging from 0.11 to 0.17 km/Ma, results from in‐sequence thick‐skinned thrusting at depth. In the outer zone of the FTB, only the younger cooling event from 15–10 Ma to 0 Ma is evident, with a cooling rate of 8.8°C/Ma and a vertical displacement rate ranging from ∼0.14 to 0.26 km/Ma, attributed to displacement along the basement‐involved Las Yeseras thrust. Furthermore, Apatite Fission Track (AFT) ages of detrital grains in the Tralalhué conglomerates support the maximum depositional age for these synorogenic strata to be between 14.1 and 9.2 Ma.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".