Producción CyT
Artículo
Autoría
Alfonso Encinas
;
Eduardo Rosselot
;
SAGRIPANTI, LUCIA
;
Andres Folguera
;
Brian Horton
;
Darío Orts
;
Valencia, V.
;
Gabriel Arriagada
;
Paz Butikofer
;
Solorzano Andrés
Fecha
2024
Editorial y Lugar de Edición
AMER JOURNAL SCIENCE
Revista
AMERICAN JOURNAL OF SCIENCE
AMER JOURNAL SCIENCE
Resumen
Información suministrada por el agente en
SIGEVA
The south-central Chile and Argentina margin experienced a regional phase of extensional tectonics during the Oligocene–early Miocene, forming several basins across the forearc, Andean Cordillera, and retroarc regions. These basins accumulated thick successions of volcanic and sedimentary rocks. Subsequently, Neogene contractional tectonics led to the development of the current Andean Cordillera and the deposition of synorogenic clastic deposits in foreland basins. Traditionally, the Cura...
The south-central Chile and Argentina margin experienced a regional phase of extensional tectonics during the Oligocene–early Miocene, forming several basins across the forearc, Andean Cordillera, and retroarc regions. These basins accumulated thick successions of volcanic and sedimentary rocks. Subsequently, Neogene contractional tectonics led to the development of the current Andean Cordillera and the deposition of synorogenic clastic deposits in foreland basins. Traditionally, the Cura Mallín Formation, comprising a lower volcanic unit (CMV) and an upper sedimentary unit (CMS), has been interpreted to have formed during the Oligocene–early Miocene extensional phase. However, some studies propose deposition of the CMS in a foreland basin during the early–late Miocene. To unravel the transition from extensional to contractional tectonics in the Andes of south-central Chile and Argentina, we conducted new geochronological analyses (U-Pb, LA-ICP-MS) and integrated these results with structural, stratigraphic, and sedimentological observations in key sections within the CMS and the overlying Trapa-Trapa Formation in the Principal Cordillera along the Chile-Argentina border (37°–38°S). Our findings indicate that only the lower part of the CMS was deposited in an extensional setting, as evidenced by the presence of an inverted extensional wedge dated at ∼20 Ma. The middle-upper CMS (∼19 to 9 Ma) and contemporaneous units to the east exhibit evidence of syncontractional deformation, suggesting deposition in a foreland basin generated by shortening of the western Principal Cordillera. Around 9 Ma, uplift of the Agrio and Chos Malal fold and thrust belts, east of the Principal Cordillera, led to the segmentation of the foreland basin. The Trapa Trapa Formation was deposited in a hinterland basin, with sediment sourced from the east. After ∼6.5 Ma, main contractional deformation shifted westward, resulting in intense folding of the CMS and Trapa Trapa Formation and subsequent thrusting of the western Principal Cordillera over the Central Depression. Our study suggests that deformation progressed toward the eastern foreland during the early to late Miocene and then shifted toward the western forearc during the late Miocene to Pleistocene.1. INTRODUCTIONThe Chilean convergent margin is characterized by the subduction of an oceanic plate beneath South America, a process that has been ongoing probably since late Paleozoic times (Charrier et al., 2007; Oliveros et al., 2018). One of the most significant features of this margin is the Andean Cordillera, the longest and highest orogen formed in an ocean-continent convergent setting. This mountain range exhibits active
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Palabras Clave
geochronological analysesCura Mallín FormationAndean CordilleraOligocene–early Miocene,