The Farallon-Aluk ridge collision with South America: Implications for the geochemical changes of slab window magmas from fore- to back-arc

Aragón, Eugenio; Pinotti, Lucio; D'Eramo, F. J.; Castro, Antonio; Rabbia, Osvaldo; Coniglio, Jorge E.; Demartis, Manuel; Hernando, Irene Raquel; Cavarozzi, Claudia E.; Aguilera, Yolanda E.

doi:10.1016/j.gsf.2012.12.004

Cited by 74 publications

(52 citation statements)

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“…The basaltic rocks intrude and cover Cretaceous sediments and are partially overlain by Quaternary debris [21][22][23]. 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].…”

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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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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“…Late Eocene-Early Oligocene: Arc Establishment Before the development of the El Maitén Belt magmatism in the North Patagonian Andes, Paleocene-middle Eocene time was characterized by the subduction of the Aluk plate beneath the South American plate, while the Aluk-Farallon mid-ocean ridge migrated southward along the margin (Cande & Leslie, 1986;Somoza & Ghidella, 2005. 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.…”

Section: 1029/2019tc005580mentioning

confidence: 99%

“…Cenozoic sedimentary and volcanic sequences of the eastern Main Patagonian Cordillera and Patagonian broken foreland form two N-to NW-striking magmatic belts between ∼40°and 43°30′S (Figure 1). The eastern Paleocene-middle Eocene Pilcaniyeu Belt (∼57.8-44 Ma) includes bimodal volcanic rocks that show within-plate geochemical signatures, presumably associated with the subduction of the Aluk-Farallon mid-ocean ridge (Aragón et al, 2013;Iannelli et al, 2017). The western late Eocene-early Miocene El Maitén Belt (∼37-19 Ma) includes basaltic to andesitic lava flows and subordinate dacitic to rhyolitic pyroclastic rocks with arc-related features ( Figure 1; Bechis et al, 2014;Benedini et al, 2017;Fernández Paz et al, 2018;Rapela et al, 1988).…”

Section: 1029/2019tc005580mentioning

confidence: 99%

“…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%

“…Particular tectonic events often disturbed the steady state of the magmatic arc, promoting lateral variations in the position of the volcanic front and modifications in the magmatic system. These events include changes in the obliquity and dip of the subducted slab, variations in the velocity of plate convergence, subduction of oceanic floor of variable ages, and collisions of midocean/aseismic ridges and terrains (e.g., Aragón et al, 2013;DeCelles et al, 2009;Ducea et al, 2015;Folguera & Ramos, 2011;Jordan et al, 2001;Kay et al, 2005;Lonsdale, 2005;Ramos et al, 2014;Schellart, 2008;Somoza & Ghidella, 2012;Turner et al, 2016;Turner & Langmuir, 2015).…”

Section: Introductionmentioning

confidence: 99%

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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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Cenozoic Deformational Processes in the North Patagonian Andes Between 40° and 43°S

Orts

Folguera

Giménez

et al. 2015

Springer Earth System Sciences

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The Farallon-Aluk ridge collision with South America: Implications for the geochemical changes of slab window magmas from fore- to back-arc

Cited by 74 publications

References 52 publications

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

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

Cenozoic Deformational Processes in the North Patagonian Andes Between 40° and 43°S

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