Tectono-magmatic response to major convergence changes in the North Patagonian suprasubduction system; the Paleogene subduction–transcurrent plate margin transition

Aragón, Eugenio; D'Eramo, F. J.; Castro, Antonio; Pinotti, Lucio; Brunelli, Daniele; Rabbia, Osvaldo; Rivalenti, Giorgio; Varela, Ricardo; Spakman, Wim; Cavarozzi, Claudia E.; Aguilera, Yolanda E.; Mazzucchelli, Maurizio; Ribot, Alejandro

doi:10.1016/j.tecto.2011.06.012

Cited by 73 publications

(83 citation statements)

References 46 publications

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“…Earliest Andean shortening was succeeded by a Maastrichtian‐Eocene gap in arc magmatic activity (including the North Patagonian Batholith) and a late Paleocene‐Eocene phase of limited retroarc deformation but considerable bimodal within‐plate volcanism (Pilcaniyeu Belt) that may represent an ignimbrite flare‐up related to initial resteepening of the subducting slab (Aragón et al, ; Rapela et al, ; Suárez & de la Cruz, ). Pronounced slab rollback during late Eocene‐earliest Miocene time was accompanied by pervasive magmatism and extension in the broken foreland system and North Patagonian Andes (El Maitén Belt and Ventana Formation), as well as the western coastal zone (Coastal Magmatic Belt) (Iannelli et al, ; Muñoz et al, ).…”

Section: Southern Andes (43°s)mentioning

confidence: 99%

Tectonic Regimes of the Central and Southern Andes: Responses to Variations in Plate Coupling During Subduction

2018

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Construction of the Andes has been governed largely by fluctuating contractional, neutral, and extensional tectonic regimes during differing degrees of mechanical coupling along the convergent plate boundary. These three contrasting regimes are likely regulated by geodynamic variations in absolute trenchward motion of South America and episodic regional shifts in the geometry of the subducting oceanic slab. Alternations among these three modes are revealed in syntheses of Mesozoic‐Cenozoic crustal deformation, basin evolution, and arc magmatism along orogen‐perpendicular transects across the central and southern Andes at 23°S, 35°S, and 43°S. Despite considerable along‐strike dissimilarities in the magnitude of deformation, a comparable tectonic regime typified the early Andean history, as defined by a transition from Late Jurassic‐Early Cretaceous postrift thermal subsidence to Late Cretaceous retroarc shortening. A key contradiction is expressed for the late middle Eocene to earliest Miocene, when neutral to extensional conditions affected retroarc to forearc regions, except in parts of the central Andes, which experienced retroarc shortening with only localized forearc extension. This mixed‐mode scenario during Paleogene time may reflect decoupling along the plate boundary (possibly during slab rollback within a retreating subduction system) in which widespread stasis or low‐magnitude extension dominated the southern Andes but was inhibited in the strongly shortened central Andes at 15–25°S where shallow subduction and/or high topography boosted plate coupling. Comparable temporal and spatial shifts in tectonic regime along the Andes and other convergent margins can be related to variable degrees of coupling during first‐order plate‐scale changes in convergence and second‐order regional cycles of slab shallowing and steepening.

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Section: Southern Andes (43°s)mentioning

confidence: 99%

Tectonic Regimes of the Central and Southern Andes: Responses to Variations in Plate Coupling During Subduction

2018

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“…The basalts are related to the Paleogene bimodal volcanism of the Piedra Parada complex [24][25][26], a large caldera eld made up of rhyolitic ignimbrites ( are up) inter-bedded with tholeiitic and alkali basalts. This extra-Andean volcanism was generated by extensional tectonics related to a transform plate margin episode that a ected the southern South America active margin from the Paleocene to the Oligocene [25]. During this stage the Aluk plate detached and a slab window opened beneath the study area.…”

Section: Geological Frameworkmentioning

confidence: 99%

Short-scale variability of the SCLM beneath the extra-Andeanback-arc (Paso de Indios, Argentina): Evidence from spinel-faciesmantle xenoliths

et al. 2015

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Cenozoic basalts carrying ultrama c mantle xenoliths occur in the Matilde, León and Chenque hills in the Paso de Indios region, Argentina. The mantle xenoliths from the Chenque and León hills mainly present porphyroclastic textures, whereas the Matilde hill xenoliths have coarse-grained to porphyroclastic textures. The equilibrium temperatures are in the range of 780 to 940• C, indicating a provenance from shallow sectors of the lithospheric mantle column that were subjected to a relatively low heat ux at Cenozoic Era. According to the modal compositions of xenoliths, the mantle beneath Matilde and León hills was a ected by greater than 22% partial melting, while less depleted peridotites occur in the Chenque suite (starting from 10% partial melting). Such an observation is con rmed by the partial melting estimates based on Cr# Sp , which vary from 8 to 14% for the selected Chenque samples and from 14 to 18% for the Matilde ones. The common melting trend is overlapped by small-scale cross cutting local trends that may have been generated by open-system processes, such as open-system partial melting and/or post partial-melting metasomatic migration of exotic Na-Cr-rich melts. The two main mineralogical reaction schemes are: i) the dissolution of pyroxenes and the segregation of new olivine in olivine-rich peridotites, and ii) the replacement of primary olivine by orthopyroxene±clinopyroxene in orthopyroxene-rich peridotites. These were produced by channelled and/or pervasive melt extraction/migration. Enhanced pyroxene dissolution is attributed to channelling of silica-undersaturated melts, whereas the replacement of primary olivine by orthopyroxene±clinopyroxene points to reaction with silica-saturated melts. Late disequilibrium reactions identi ed in the xenoliths comprise: the breakdown of orthopyroxene in contact with the host basalt, and (rarely) reaction coronae on orthopyroxene, clinopyroxene and spinel linked to glassy veins. Such features are apparently related to the injection of melt, likely during entrainment into the host basalts and ascent to the surface.

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“…Recent plate reconstructions show low absolute convergence rates for this period that could have led to extensional conditions along the margin, which went along with the development of the intraplate associations of the Pilcaniyeu Belt in the former backarc and a waning in arc activity as the subducted plate decelerated (Figures 7, 8a, and 8b; ∼57.8-44 Ma; Aragón, D'Eramo, et al, 2011, Aragón et al, 2013Iannelli et al, 2017;Matthews et al, 2016;Somoza & Ghidella, 2005). Aragón, D'Eramo, et al (2011) and Aragón et al (2013) proposed that after the subduction of the Aluk-Farallon mid-ocean ridge, the Aluk plate detached and the subduction of the Farallon plate was interrupted. Recent studies focused both in the Andean margin and in other subduction zones around the world had shown that after ridge subduction, a period of slow subduction occurred until slab-pull force was restored, and so arc magmatism (Fennell et al, 2018;Sun et al, 2018).…”

Section: 1029/2019tc005580mentioning

confidence: 99%

“…The right column comprises the tectonic schemes for the different stages of North Patagonian Andes evolution. Ages of magmatic units are from , Aragón, D'Eramo, et al (2011), Ardolino and Franchi (1993), Bechis et al (2014), Benedini et al (2017), Coira et al (1985), Corbella (1982aCorbella ( , 1982b, Encinas et al (2016), Fernández Paz et al (2018), González Díaz (1979, Henríquez Ascencio (2016), Hervé et al (1995), Iannelli et al (2017), Kay et al (2007), Lizuain and Viera (2010), Marshall et al (1983Marshall et al ( , 1986, Mazzoni et al (1991), Muñoz et al (2000), Ramos et al (2014), Rapela et al (1983Rapela et al ( , 1988, Remesal et al (2012), and Turner (1982).…”

Section: 1029/2019tc005580mentioning

confidence: 99%

Constraints on Trenchward Arc Migration and Backarc Magmatism in the North Patagonian Andes in the Context of Nazca Plate Rollback

et al. 2019

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Geochemical and geochronological data reveal that late Oligocene‐early Miocene time is a break point in the evolution of Andean magmatism. The Patagonian Andes registered the onset of arc volcanism since the late Eocene forming part of the El Maitén Belt, whose development was driven by the subduction of the Farallon/Nazca plates beneath the Andean margin. During the Oligocene, the El Maitén Belt shows a change in the geochemical signature of its magmas from tholeiitic to calc‐alkaline compositions, reflecting a more mature stage in the magmatic arc evolution. Toward the early Miocene, a striking event is registered in Andean volcanic sequences as mafic tholeiitic lava flows of the El Maitén are interbedded with marine deposits, suggesting their development in the context of a fast subsiding regime. Geochemical analyses presented in this paper show that these rocks resemble enriched mid‐ocean ridge basalt‐like and ocean island basalt compositions, isotopically depleted, which strongly contrast with previous arc products. By this time, a global plate reorganization event had caused an increase in convergence rates, accelerated rollback, and a more orthogonal geometry of subduction, triggering widespread magmatism and the development of extensional basins in the overriding plate. Arc‐related volcanism during the early Miocene can be found only in the western slope of the Andes, suggesting the retreat of the volcanic front toward the trench. The proposed model highlights a strong linkage between the geochemical signature of magmatic products and changes in the subduction zone configuration and mantle dynamics during the evolution of the Patagonian Andes (41–44°S).

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Tectono-magmatic response to major convergence changes in the North Patagonian suprasubduction system; the Paleogene subduction–transcurrent plate margin transition

Cited by 73 publications

References 46 publications

Tectonic Regimes of the Central and Southern Andes: Responses to Variations in Plate Coupling During Subduction

Tectonic Regimes of the Central and Southern Andes: Responses to Variations in Plate Coupling During Subduction

Short-scale variability of the SCLM beneath the extra-Andeanback-arc (Paso de Indios, Argentina): Evidence from spinel-faciesmantle xenoliths

Constraints on Trenchward Arc Migration and Backarc Magmatism in the North Patagonian Andes in the Context of Nazca Plate Rollback

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