Biostratigraphic and paleobiogeographic significance of the Darriwilian microfossils from the top of San Juan Formation in the Los Baños de Talacasto section, Central Precordillera (Argentina)
Bibliographic record
Abstract
The microfossil hosted in the strata of the upper part of the San Juan Formation has been widely studied in several sections to the northward of the Argentinian Central Precordillera. In contrast, the coeval strata at the Los Baños de Talacasto section, in the southern part of the Central Precordillera, have scarce biostratigraphic and sedimentological data. In this work, a conodont association together with single ostracod species are documented for the first time in this section. The record of the Lenodus crassus and L. pseudoplanus zones confirms the Darriwilian age for these beds and accurately correlates them with equivalent strata of the San Juan Formation studied in several sections of the Central and Eastern Precordillera. The microfacies analysis verifies the presence of Nuia síbirica Maslov, 1954, peloids, intraclasts, cyanobacteria, calcareous algae, and a possible microbialite indicating a shallow warm-water subtidal environment, in equatorial to subequatorial climate. This suggests a low latitudes position for Precordillera during the early-middle Darriwilian. The conodont genus Aurilobodus Xiang and Zhang is recognized for the first time from the Precordillera, and the Aurilobodus leptosomatus An specimens are described and illustrated. This genus shows affinities to the warm water in shallow marine environments of North China, Central Asia, South Tibet, western Thailand, Australia, and Newfoundland, suggesting probable ties between Precordillera and these regions. The record of the ostracod Pilla nodospinosa Salas in the study section would agree with the correlation of the top of San Juan Formation with the lower levels of the Las Aguaditas Formation in the Central Precordillera, and also suggests paleobiogeographic links with Eastern Gondwana and Australia regions during the Darriwilian times.
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 | 0.000 | 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".