Contextualización geológica e inferencias paleo-ecológicas de las maderas fósiles de la comuna de Nacimiento, Chile
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Fecha
2023
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Facultad/escuela
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es
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Universidad Andrés Bello
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Licencia CC
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Resumen
La comuna de estudio, Nacimiento, situada en el sureste de Concepción, alberga un valioso patrimonio paleontológico, en
particular, un registro paleobotánico que incluye palinomorfos, impresiones de hojas y maderas fósiles. Este trabajo está
enfocado particularmente en el registro de maderas fósiles, otorgando contexto geológico y paleo-ecológico.
En cuanto al contexto geológico, este se realiza por medio de análisis geomorfológico, sedimentario, estratigráfico y tafonómico.
Se generaron perfiles topográficos tanto en Nacimiento, como en Renaico, Tijeral y Angol. En cuanto a la sedimentología y
estratigrafía, las maderas fósiles se encuentran dentro de una capa de gravas polimícticas, esta capa se denominó Litofacies 3.
Por último, tafonómicamente de los resultados se desprende que la silicificación de los ejemplares vistos al microscopio es de
cuarzo, además, solo una muestra contiene minerales metálicos de plata nativa y pirita, y drusas de cuarzo prismático que
ocasionalmente se rellenan por esmectita. Esto se traduce en que las maderas fósiles encontradas en los estratos de las Comunas
de Nacimiento y Renaico no son in situ, más bien son aportes fluviales del Río Vergara, con un origen hidrotermal donde fluidos
ricos en sílice mineralizan las estructuras anatómicas de las maderas.
Por otra parte, la clasificación taxonómica solo se logró realizar a nivel de especie en el ejemplar ZPA-14 el cual resultó en
Nothofagoxylon scalariforme (afín al Sauce); y a nivel de Angiosperma en el ejemplar ZPA-13. Nishida (1984), describe dos
ejemplares para la región, uno proveniente de Nacimiento y otro de Cerro Huimpil en Temuco, Cupressinoxylon austrocedroides
(afín al Ciprés de la Montaña), y Proteoxylon sp. (afín a las Proteaceas), respectivamente. Paleo-ecológicamente se asocian a
climas mediterráneos subtropicales que propician bosques caducifolios mediterráneos.
The study's municipality, Nacimiento, located in the southeast of Concepción, houses a valuable paleontological heritage, particularly a paleobotanical record that includes palynomorphs, leaf impressions, and fossilized wood. This work is particularly focused on the fossilized wood record, providing geological and paleoecological context. Regarding the geological context, this is achieved through geomorphological, sedimentary, stratigraphic, and taphonomic analyses. Topographic profiles were generated in Nacimiento, as well as in Renaico, Tijeral, and Angol. In terms of sedimentology and stratigraphy, the fossilized woods are found within a layer of polymictic gravels, referred to as Lithofacies 3. Finally, taphonomically, the results indicate that the silicification of the specimens observed under the microscope is of quartz. Additionally, only one sample contains native silver and pyrite metallic minerals, and prismatic quartz druses that are occasionally filled with smectite. This translates to the fossilized woods found in the strata of the municipalities of Nacimiento and Renaico not being in situ; instead, they are fluvial contributions from the Vergara River, with a hydrothermal origin where silica-rich fluids mineralize the anatomical structures of the woods. On the other hand, taxonomic classification was only achieved at the species level in the specimen ZPA-14, which resulted in Nothofagoxylon scalariforme (similar to Willow); and at the angiosperm level in the specimen ZPA-13. Nishida (1984) described two specimens for the region, one from Nacimiento and another from Cerro Huimpil in Temuco, Cupressinoxylon austrocedroides (similar to Mountain Cypress), and Proteoxylon sp. (similar to Proteaceae), respectively. Paleo-ecologically, they are associated with subtropical Mediterranean climates that favor deciduous Mediterranean forests
The study's municipality, Nacimiento, located in the southeast of Concepción, houses a valuable paleontological heritage, particularly a paleobotanical record that includes palynomorphs, leaf impressions, and fossilized wood. This work is particularly focused on the fossilized wood record, providing geological and paleoecological context. Regarding the geological context, this is achieved through geomorphological, sedimentary, stratigraphic, and taphonomic analyses. Topographic profiles were generated in Nacimiento, as well as in Renaico, Tijeral, and Angol. In terms of sedimentology and stratigraphy, the fossilized woods are found within a layer of polymictic gravels, referred to as Lithofacies 3. Finally, taphonomically, the results indicate that the silicification of the specimens observed under the microscope is of quartz. Additionally, only one sample contains native silver and pyrite metallic minerals, and prismatic quartz druses that are occasionally filled with smectite. This translates to the fossilized woods found in the strata of the municipalities of Nacimiento and Renaico not being in situ; instead, they are fluvial contributions from the Vergara River, with a hydrothermal origin where silica-rich fluids mineralize the anatomical structures of the woods. On the other hand, taxonomic classification was only achieved at the species level in the specimen ZPA-14, which resulted in Nothofagoxylon scalariforme (similar to Willow); and at the angiosperm level in the specimen ZPA-13. Nishida (1984) described two specimens for the region, one from Nacimiento and another from Cerro Huimpil in Temuco, Cupressinoxylon austrocedroides (similar to Mountain Cypress), and Proteoxylon sp. (similar to Proteaceae), respectively. Paleo-ecologically, they are associated with subtropical Mediterranean climates that favor deciduous Mediterranean forests
Notas
Tesis (Geóloga)
Palabras clave
Geología, Paleoecología, Maderas Fósiles, Chile, Nacimiento