Producción CyT
Congreso
Autoría
Fecha
2022
Editorial y Lugar de Edición
Asociación Geológica Argentina
ISSN
978-987-48319-9-6
Resumen
Información suministrada por el agente en
SIGEVA
low lying area known as the Central Depression. The origin of these morphostructural units has been largely debated. They have been ascribed to different ages between the Cretaceous and the Pliocene, and causes that involve extensional or contractional deformation and have been related to Andean evolution or accretionary processes in the forearc, or even to differential erosion (Brüggen 1950, Gana and Wall 1997, Muñoz et al. 2000, Farías y Charrier 2008, Rehak et al. 2008, Me...
low lying area known as the Central Depression. The origin of these morphostructural units has been largely debated. They have been ascribed to different ages between the Cretaceous and the Pliocene, and causes that involve extensional or contractional deformation and have been related to Andean evolution or accretionary processes in the forearc, or even to differential erosion (Brüggen 1950, Gana and Wall 1997, Muñoz et al. 2000, Farías y Charrier 2008, Rehak et al. 2008, Melnick et al. 2009, Armijo et al. 2010, Giambiagiet al. 2014). To investigate the geologic evolution of the Coastal Cordillera and Central Depression in the cited area, we based on stratigraphy, sedimentology, geochronology (U-Pb, LA-ICP-MS), structuralgeology, and geomorphology. Our studies, which are based on our own data and a thorough bibliographic review, indicate the following sequence of events in the tectono-sedimentary evolution of the forearc of south-central Chile during the late Cenozoic. The area was subjected to extensional tectonics caused byslab rollback during the Oligocene-early Miocene, resulting in the genesis of a series of basins filled with volcanic, continental, and marine deposits that extended from the present Chilean coast to the retroac.The extensional basins were tectonically inverted during the late Early-Late Miocene, and most of the forearc became a positive relief that was subjected to fluvial erosion. The West Andean Thrust, a major reverse west verging fault in the limit between the Central Depression and the Andean Cordillera, causedsignificant uplift of the western flank of the Andes. This triggered flexural subsidence and the accumulation of coarse-grained deposits in the forearc during the Pliocene-Pleistocene. The sudden increase of sediment flux to the trench during this period caused a change from non-accretion or subduction erosion to accretion in the margin of south-central Chile. Progressive growth of the accretionary wedge gave birth to a forearc high, the Coastal Cordillera, which was uplifted in the last 2 Ma. Some forearc areas placed above subductedoceanic fracture zones did not experience uplift during this period due to the signifi cant transport of fl uid that inhibited the deformation of the accretionary wedge. Our studies show that the late Cenozoictectono-sedimentary evolution of the forearc in the study area is complex and involves diff erent processes related to Andean evolution in the fi rst stage and accretionary processes acting exclusively in the forearcin a second stage. The Coastal Cordillera and the Central Depression of south-central Chile were developed in the last 2 Ma and are much younger than classically considered (Encinas et al. 2021).
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Palabras Clave
GeocronologíaDepresión centralChile centro-surCordilelra de la Costa