Caracterización geoquímica de los volcanes Descabezado Grande, Cerro Azul, Quizapu y centros eruptivos aledaños, Región del Maule, Chile
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Fecha
2021
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Facultad/escuela
Idioma
es
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Universidad Andrés Bello
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Licencia CC
Licencia CC
Resumen
Los centros eruptivos ubicados entre los 35° a 35.5°S se encuentran dentro de la denominada Zona
Volcánica Sur Transicional (ZVST), donde destacan los centros eruptivos como Descabezado
Grande, Cerro Azul y Quizapu. Dentro de la zona es posible encontrar una amplia diversidad de
magmas que varían desde magmas de composición riolítica a magmas basálticos con signaturas
de mantélica. Esto se podría deber al control estructural presente en la zona, donde conviven
espacio – temporalmente regímenes transpresionales y transtensionales ligados a estructuras
primitivas. Otro factor importante es la gruesa corteza que alcanza un espesor de entre 45 a 50 km.
La importancia del estudio de la zona se deriva de su historia eruptiva, ya que se han registrado
importantes erupciones, tales como las erupciones de 1846 – 1847 y 1932 del Volcán Quizapu. El
proyecto de memoria de título presentado intenta identificar la procedencia de los depósitos de
tefra asentados posterior al retiro del último periodo glacial, ocurrido en la zona (20 Ma) y así
obtener información de la actividad de los múltiples centros eruptivos. Para esto se realizó una
caracterización de los centros eruptivos, a través de químicas conocidas (muestras obtenidas
desde los edificios volcánicos), que fueron comparadas con las químicas desconocidas (muestras
obtenidas de depósitos de tefra de origen desconocido) para intentar establecer su centro de
origen. Los resultados indicaron que todos los centros eruptivos son cogenéticos, presentando
patrones y concentraciones elementales similares para los mismos grados de diferenciación, por
lo que no se pudo determinar el origen exacto para las químicas desconocidas. Sin embargo, sí se
pudo acotar su procedencia a un grupo de centros eruptivos. Igualmente, a través del análisis de
concentraciones elementales se pudo obtener información sobre los procesos involucrados en la
diferenciación magmática y relacionarlos al control estructural.
The eruptive centers located between 35° to 35.5°S are located within the so-called South Transitional Volcanic Zone (STVZ), where eruptive centers such as Descabezado Grande, Cerro Azul and Quizapu stand out. Within the zone it is possible to find a wide diversity of magmas that vary from magmas of rhyolitic composition to basaltic magmas with signatures of mantle composition. This could be due to the structural control present in the area, where transpressional and transtensional regimes linked to primitive structures coexist spatially and temporally. Another important factor is the thick crust that reaches a thickness of 45 to 50 km. The importance of the study of the area derives from its eruptive history since important eruptions have been recorded, such as the 1846-1847 and 1932 eruptions of the Quizapu Volcano. The title memory project presented attempts to identify the origin of the tephra deposits settled after the retreat of the last glacial period in the area (20 m.a) and thus obtain information on the activity of the multiple eruptive centers. For this purpose, a characterization of the eruptive centers was carried out through known chemistry (samples obtained from volcanic buildings), which were compared with unknown chemistry (samples obtained from tephra deposits of unknown origin) to try to establish their center of origin. The results indicated that all the eruptive centers are cogenitic, presenting similar patterns and elemental concentrations for the same degrees of differentiation, so the exact origin of the unknown chemistry could not be determined. However, it was possible to narrow down their origin to a group of eruptive centers. Likewise, through the analysis of elemental concentrations it was possible to obtain information about the processes involved in magmatic differentiation and relate them to structural control.
The eruptive centers located between 35° to 35.5°S are located within the so-called South Transitional Volcanic Zone (STVZ), where eruptive centers such as Descabezado Grande, Cerro Azul and Quizapu stand out. Within the zone it is possible to find a wide diversity of magmas that vary from magmas of rhyolitic composition to basaltic magmas with signatures of mantle composition. This could be due to the structural control present in the area, where transpressional and transtensional regimes linked to primitive structures coexist spatially and temporally. Another important factor is the thick crust that reaches a thickness of 45 to 50 km. The importance of the study of the area derives from its eruptive history since important eruptions have been recorded, such as the 1846-1847 and 1932 eruptions of the Quizapu Volcano. The title memory project presented attempts to identify the origin of the tephra deposits settled after the retreat of the last glacial period in the area (20 m.a) and thus obtain information on the activity of the multiple eruptive centers. For this purpose, a characterization of the eruptive centers was carried out through known chemistry (samples obtained from volcanic buildings), which were compared with unknown chemistry (samples obtained from tephra deposits of unknown origin) to try to establish their center of origin. The results indicated that all the eruptive centers are cogenitic, presenting similar patterns and elemental concentrations for the same degrees of differentiation, so the exact origin of the unknown chemistry could not be determined. However, it was possible to narrow down their origin to a group of eruptive centers. Likewise, through the analysis of elemental concentrations it was possible to obtain information about the processes involved in magmatic differentiation and relate them to structural control.
Notas
Memoria (Geólogo)
Palabras clave
Vulcanismo, Geoquímica, Magmatismo, Chile, Región del Maule