Estuary deposits in the Rio Baguales Formation (Chattian-Aquitanean), Magallanes Province, Chile.
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Jacobus P. Le Roux [1] ; Jacqueline Puratich [1] ; F. Amaro Mourgues ; José Luis Oyarzún ; Rodrigo A. Otero [2] ; Teresa Torres González [1] ; Francisco Hervé [1]
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[1] Universidad de Chile
Universidad de Chile
Santiago, Chile
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[2] Consejo de Monumentos Nacionales. Chile
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- Localización: Andean geology: Formerly Revista geológica de Chile, ISSN-e 0718-7106, ISSN 0718-7092, Vol. 37, Nº. 2, 2010, págs. 329-344
- Idioma: inglés
- Enlaces
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Resumen
Very little work has been done on the stratigraphy and sedimentology of the upper Oligocene-Lower Miocene Río Baguales Formation in the Magallanes Province of southern Chile since its original definition in 1957. A detailed stratigraphic section of the upper part of the formation exposed west of the Baguales River is presented, with an interpretation of depositional environments. This indicates a prograding shoreline in which estuary mouth, middle estuary (lagoon) and bay head delta facies are represented. Large-scale delta slope foresets indicate progradation towards the north and northwest, whereas southeast-directed cross-beds on the delta front probably suggest wave action. The general sequence reflects a gradual sea-level fall largely counteracted by tectonic subsidence, which provided the necessary accommodation space for thick tidal flat and subtidal deposits to accumulate. A longer period of transgression towards the top of the succession may be related to a rise in sea-level or accelerated tectonic subsidence, whereas a major regression commencing at around 23.3 Ma probably coincides with the opening of the Drake Passage and the growth of the East Antarctic Ice Sheet.
