Estratigrafía y sedimentología Mesozoica en torno a Puerto Ingeniero Ibáñez (~46°17?S), Cordillera Patagónica, Región de Aysén, Chile
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Fecha
2018
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Facultad/escuela
Idioma
es
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Universidad Andrés Bello
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Licencia CC
Licencia CC
Resumen
La estratigrafía de la Cordillera Patagónica en torno a los 46°S, se encuentra caracterizada por una sucesión de rocas sedimentarias y volcánicas mesozoicas, incluidas en el Grupo Coyhaique y la subyacente Formación Ibáñez, que cubren discordantemente al basamento de edad Paleozoico. Este trabajo describe al Grupo Coyhaique, que corresponde a la unidad sedimentaria marina de este período, que está intercalada entre las formaciones Ibáñez y Divisadero, a la base y techo respectivamente.
El análisis estratigráfico y sedimentológico permite distinguir seis asociaciones de facies, la primera de origen volcánico asociado a un vigoroso evento eruptivo correspondiente a la Formación Ibáñez con edades del Jurásico Superior al Cretácico Inferior. Suprayacente, se genera un evento de transgresión marina contemporáneo a las etapas finales de este volcanismo durante el Titoniano – Aptiano. En este tramo se distinguen dos asociaciones de facies, representadas por la Formación Katterfeld, que contextualizan a la unidad en un ambiente marino profundo. Posteriormente, ocurre un proceso de regresión marina que conforma la cuarta y quinta asociación de facies, en un ambiente marino oxigenado a costero-sublitoral, caracterizado por la Formación Apeleg. Finalmente, el paulatino incremento de actividad volcánica durante el Aptiano, en conjunto con una disminución del aporte de sedimentos marinos, marca la sexta asociación de facies en un ambiente subaéreo, correspondiente a la Formación Divisadero.
La integración de los resultados obtenidos en este trabajo, en materia de proveniencia sedimentaria, propone que el alto contenido de cuarzo que caracteriza las rocas de la Formación Apeleg, corresponderían en parte a fragmentos heredados de la Formación Ibáñez, unidad subyacente, y rica en rocas volcánicas ácidas. Ello sumado a aportes desde el NE, en Argentina, correspondiente a rocas del sistema volcánico Toarciano representado por la Formación Marifil y/o Plutones Subcordilleranos, caracterizados por ignimbritas riolíticas y granitoides respectivamente.
The stratigraphy of the Patagonian Cordillera around 46°S, is characterized by a succession of Mesozoic sedimentary and volcanic rocks, included in the Coyhaique Group and the underlying Ibáñez Formation, which discordantly cover the Paleozoic age basement. This work describes the Coyhaique Group, which corresponds to the marine sedimentary unit of this period, which is interspersed between the Ibáñez and Divisadero Formations, to the base and top respectively. The stratigraphic and sedimentological analysis allows to distinguish six facies associations, the first of volcanic origin associated with a vigorous eruptive event corresponding to the Ibáñez Formation with ages from the Upper Jurassic to the Lower Cretaceous. Overlying, a contemporary marine transgression event is generated to the final stages of this volcanism during the Titonian – Aptian. In this section there are two facies associations, represented by the Katterfeld Formation, which contextualize the unit in a deep marine environment. Subsequently, a marine regression process takes place that makes up the fourth and fifth facies association, in an oxygenated to coastal-sublittoral marine environment, characterized by the Apeleg Formation. Finally, the gradual increase of volcanic activity during the Aptian, together with a decrease in the contribution of marine sediments, marks the sixth facies association in a subaerial environment, corresponding to the Divisadero Formation. The integration of the results obtained in this work, in terms of sedimentary provenience, propose that the high quartz content that characterizes the rocks of the Apeleg Formation, would correspond in part to fragments inherited from the Ibáñez Formation, an underlying unit, and rich in acidic volcanic rocks. This added to contributions from NE, in Argentina, corresponding to rocks of the Toarcian volcanic system represented by the Marifil Formation and/or Subcordilleran Plutonic belt, characterized by rhyolitic ignimbrites, and granitoids respectively.
The stratigraphy of the Patagonian Cordillera around 46°S, is characterized by a succession of Mesozoic sedimentary and volcanic rocks, included in the Coyhaique Group and the underlying Ibáñez Formation, which discordantly cover the Paleozoic age basement. This work describes the Coyhaique Group, which corresponds to the marine sedimentary unit of this period, which is interspersed between the Ibáñez and Divisadero Formations, to the base and top respectively. The stratigraphic and sedimentological analysis allows to distinguish six facies associations, the first of volcanic origin associated with a vigorous eruptive event corresponding to the Ibáñez Formation with ages from the Upper Jurassic to the Lower Cretaceous. Overlying, a contemporary marine transgression event is generated to the final stages of this volcanism during the Titonian – Aptian. In this section there are two facies associations, represented by the Katterfeld Formation, which contextualize the unit in a deep marine environment. Subsequently, a marine regression process takes place that makes up the fourth and fifth facies association, in an oxygenated to coastal-sublittoral marine environment, characterized by the Apeleg Formation. Finally, the gradual increase of volcanic activity during the Aptian, together with a decrease in the contribution of marine sediments, marks the sixth facies association in a subaerial environment, corresponding to the Divisadero Formation. The integration of the results obtained in this work, in terms of sedimentary provenience, propose that the high quartz content that characterizes the rocks of the Apeleg Formation, would correspond in part to fragments inherited from the Ibáñez Formation, an underlying unit, and rich in acidic volcanic rocks. This added to contributions from NE, in Argentina, corresponding to rocks of the Toarcian volcanic system represented by the Marifil Formation and/or Subcordilleran Plutonic belt, characterized by rhyolitic ignimbrites, and granitoids respectively.
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Tesis (Geólogo)
Palabras clave
Estratigrafía, Investigaciones, Chile, Puerto Ingeniero Ibáñez, Sedimentología