Publication: Revisión Estratigráfica del Complejo volcánico Marifil
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Asociación Geológica Argentina
Abstract
La definición del Complejo Volcánico Marifil ha variado desde su definición en 1974 para incluir una gran variedad de rocas ígneas, sedimentarias y piroclástica de edad y génesis diferentes. Recientes contribuciones han propuesto la existencia de un régimen tectónico extensional durante el Triásico Medio, vinculado posiblemente al colapso del orógeno Gondwanico al cual se ha asociado un magmatismo mesosilícico. Por otra parte, el vulcanismo acido del Jurásico de la Patagonia ha sido atribuido a un régimen extensional de intraplaca continental asociado a la actividad térmica de la Pluma del Karoo. En cada uno de estos escenarios tectónicos, se han desarrollado sistemas sedimentarios restringidos y con una importante componente volcaniclástica. Los diferentes tipos de roca formados durante los mencionados eventos geotectónicos (litogenéticos) han sido individualizados y nombrados en diferentes áreas geográficas bajo diferentes denominaciones formales. Incluso unidades litológicas de similar composición y posición estratigráfica han recibido nombres diferentes en áreas aledañas. Considerando que la génesis de las rocas, así como su posición estratigráfica, son factores fundamentales para la definición de una unidad litoestratigráfica, proponemos en esta contribución un reordenamiento estratigráfico para las unidades volcánicas, volcaniclásticas, intrusivas y sedimentarias del Triásico Medio a Jurásico Inferior aflorantes en la vertiente oriental del Macizo Nordpatagónico incluidas hasta el momento en el Complejo Volcánico Marifil.
The definition of the Marifil Volcanic Complex has varied since its definition in 1974 to include a wide variety of igneous, sedimentary, and pyroclastic rocks of different ages and genesis. Recent contributions have proposed the existence of an extensional tectonic regime during the Middle Triassic, possibly linked to the collapse of the Gondwanic orogen to which a mesosilicic magmatism has been associated. On the other hand, the acid volcanism of the Jurassic of Patagonia has been attributed to a continental intraplate extensional regime associated with the thermal activity of the Karoo Plume. In each of these tectonic scenarios, restricted sedimentary systems have been developed with an important volcaniclastic component. The different types of rock formed during the aforementioned geotectonic (lithogenetic) events have been individualized and named in different geographical areas under different formal denominations. Even lithological units of similar composition and stratigraphic position have received different names in neighboring areas. Considering that the genesis of the rocks, as well as their stratigraphic position, are fundamental factors for the definition of a lithostratigraphic unit, we propose in this contribution a stratigraphic rearrangement for the volcanic, volcaniclastic, intrusive and sedimentary units of the Middle Triassic to Lower Jurassic outcropping in the eastern slope of the North Patagonian Massif included up to now in the Marifil Volcanic Complex.
The definition of the Marifil Volcanic Complex has varied since its definition in 1974 to include a wide variety of igneous, sedimentary, and pyroclastic rocks of different ages and genesis. Recent contributions have proposed the existence of an extensional tectonic regime during the Middle Triassic, possibly linked to the collapse of the Gondwanic orogen to which a mesosilicic magmatism has been associated. On the other hand, the acid volcanism of the Jurassic of Patagonia has been attributed to a continental intraplate extensional regime associated with the thermal activity of the Karoo Plume. In each of these tectonic scenarios, restricted sedimentary systems have been developed with an important volcaniclastic component. The different types of rock formed during the aforementioned geotectonic (lithogenetic) events have been individualized and named in different geographical areas under different formal denominations. Even lithological units of similar composition and stratigraphic position have received different names in neighboring areas. Considering that the genesis of the rocks, as well as their stratigraphic position, are fundamental factors for the definition of a lithostratigraphic unit, we propose in this contribution a stratigraphic rearrangement for the volcanic, volcaniclastic, intrusive and sedimentary units of the Middle Triassic to Lower Jurassic outcropping in the eastern slope of the North Patagonian Massif included up to now in the Marifil Volcanic Complex.