The late Eocene–early Miocene El Maitén Belt evolution: Magmatic response to the changing subduction zone geodynamics

Paz, Lucía Fernández; Iannelli, Sofía B.; Echaurren, Andrés; Ramos, Miguel; Bechis, Florencia; Litvak, Vanesa D.; Encinas, Alfonso; Kasemann, Simone A.; Lucassen, Friedrich; Folguera, Andrés

doi:10.1016/j.jsames.2020.102713

Cited by 12 publications

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References 94 publications

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“…Notably, certain areas in the eastern forearc and the Andes (~41°-46°S) feature upper Oligocene-lower Miocene marine deposits interbedded with volcanic lavas from the Traiguén and Ventana formations (fig. 1; Encinas et al, 2016;Fernández Paz et al, 2020). Additionally, reported the presence of both Pacific and Atlantic molluscan taxa in upper Oligocene-lower Miocene marine strata in the Andes at ~43°S, suggesting a temporary connection between both seas during this period.…”

Section: Introductionmentioning

confidence: 89%

“…Several authors have linked the formation of upper Oligocene-lower Miocene basins to a regional episode of extensional tectonics (Charrier et al, 2002;Encinas et al, 2016Encinas et al, , 2018Jordan et al, 2001;Kay & Copeland, 2006;Muñoz et al, 2000). Evidence primarily relies on the geochemistry of volcanic rocks, which exhibit a complex mixture of slab signatures and pristine mantle sources, suggesting a thinned crust (Encinas et al, 2016;Fernández Paz et al, 2020;Jordan et al, 2001;Kay & Copeland, 2006;Muñoz et al, 2000). In addition, structural studies conducted on outcrops and seismic lines reveal the presence of synextensional sedimentation in volcanic and sedimentary deposits (Elgueta et al, 2000;Encinas et al, 2016;Fennell et al, 2019;García Morabito & Ramos, 2012;Orts et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…These findings imply that the Andean Cordillera, at least at the mentioned latitudes, had likely not yet formed. The presence of uplifted upper Oligocene-lower Miocene marine strata reaching elevations of approximately 2000 m above sea level indicate that Andean shortening took place after the early Miocene (Bechis et al, 2014;Encinas et al, 2019;Fernández Paz et al, 2020). Nevertheless, Colwyn The figure includes labels indicating the names of the most significant units.…”

Section: Introductionmentioning

confidence: 99%

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Cenozoic Basin Evolution During Alternating Extension and Shortening in the Southern Central Andes Along the Chile-Argentina Border, 37–38°S

Encinas,

Rosselot,

Sagripanti

et al. 2024

American Journal of Science

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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 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, major 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.

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Section: Introductionmentioning

confidence: 89%