Variabilidad de la icnofacies de Glossifungites en el contacto entre las Formaciones Sarmiento (Eoceno medio - Mioceno temprano) y Chenque (Mioceno temprano) en el Golfo San Jorge, Chubut, Argentina
Bibliographic record
Abstract
Resumen. Este estudio esta centrado en las caracteristicas icnologicas y estratigraficas del contacto entre la Formacion Sarmiento (Eoceno medio - Mioceno temprano) y la Formacion Chenque (Mioceno temprano). Los afloramientos analizados se localizan en las cercanias de la ciudad de Comodoro Rivadavia, provincia del Chubut, Patagonia, Argentina. El contacto estudiado representa una superficie co-planar de erosion de nivel de mar bajo y erosion transgresiva que produjo la exhumacion de los depositos pertenecientes a la Formacion Sarmiento, permitiendo el desarrollo de la icnofacies de Glossifungites. Esta icnofacies es caracteristica de sedimentos compactados y deshidratados (sustratos firmes) y comprende una suite de trazas fosiles particulares que se desarrollan en ambientes con control del sustrato. En los afloramientos analizados (Astra, bahia Solano e Infiernillo), este contacto fue colonizado por crustaceos decapodos constructores de galerias (Thalassinoides isp.) y bivalvos productores de estructuras de habitacion (Gastrochaenolites ornatus). A pesar que la composicion taxonomica no presenta variaciones significativas, se pueden inferir importantes diferencias de caracter paleoecologico entre las asociaciones de trazas fosiles preservadas en cada uno de los afloramientos. Las asociaciones modernas de organismos que colonizan superficies firmes parecen estar controladas por tres parametros principales: la textura del sedimento, la firmeza del sustrato y la batimetria. En las sucesiones miocenas, la variabilidad hallada en los diferentes ejemplos de la icnofacies de Glossifungites estaria controlada probablemente por la firmeza de la superficie exhumada durante la transgresion Leonense. El analisis del contenido icnologico, el truncamiento de las estructuras y la relacion existente entre las trazas fosiles sugiere una compleja historia para esta superficie, con sucesivos eventos de ravinamiento erosivo y colonizacion bentonica. Abstract. VARIABILITY OF THE GLOSSIFUNGITES ICHNOFACIES AT THE BOUNDARY BETWEEN THE SARMIENTO FORMATION (MIDDLE EOCENE- EARLY MIOCENE) AND CHENQUE FORMATION (EARLY MIOCENE) IN SAN JORGE GULF, CHUBUT, ARGENTINA.This study focuses on the ichnologic and stratigraphic characteristics of the boundary surface between the Sarmiento (middle Eocene- early Miocene) and Chenque Formations (early Miocene). The analyzed outcrops are located near Comodoro Rivadavia city, Chubut Province, Patagonia, Argentina. The studied boundary represents a co-planar surface of lowstand erosion and transgressive erosion that produced exhumation of deposits belonging to the Sarmiento Formation, allowing the development of the Glossifungites ichnofacies. This ichnofacies is characteristic of stiff and dewatered sediments (firmgrounds) and comprises a particular suite of substrate-controlled trace fossils. In the studied outcrops (Astra, bahia Solano and Infiernillo), this boundary surface was colonized by decapod crustaceans that constructed galleries (Thalassinoides isp.) and bivalves that constructed dwelling structures (Gastrochaenolitesornatus). Although in all these localities the ichnotaxonomic composition does not show significant variations, important paleoecological differences between the trace fossil suites preserved in each outcrop can be inferred. Recent assemblages that colonize firmground surfaces seem to be controlled by three main parameters: sediment texture, substrate firmness and bathymetry. In the Miocene examples, the observed variability of the Glossifungites ichnofacies was probably controlled by the firmness of the surface exhumed during the Leonense transgression. Analysis of the ichnologic content, truncation of trace fossils, and the relationship between biogenic structures suggests a complex history for this erosive surface, involving successive events of ravinement erosion and benthic colonization.
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 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 | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".