Evolução geoquímica de peridotitos e piroxenitos do Manto Litosférico Subcontinental do vulcão Agua Poca, Terreno Cuyania, Argentina

Jalowitzki, Tiago; Conceição, Rômmulo Vieira; Orihashi, Yuji; Bertotto, Gustavo Walter; Nakai, S.; Schilling, Manuel

doi:10.22456/1807-9806.22656

Cited by 9 publications

(10 citation statements)

References 2 publications

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“…Red circles indicate the data point constraints selected from seismic profiles that were used in the crustal thickness model of Assumpção et al (2013) which was utilized to derive the depth of the continental Moho. The blue diamond shows the sample location for the mantle xenoliths (Conceicao et al 2005;Jalowitzki et al 2010). The black rectangle shows the extent of the study area.…”

Section: Setup Of the Initial Modelmentioning

confidence: 99%

“…The S-wave velocities from the SL2013sv model were converted into densities using the Python Velocity Conversion tool (Meeßen 2017; see Supplementary Material), following a modified approach developed by Goes et al (2000). To compute mantle densities, this method required a mantle composition, which we derived from the petrology and geochemistry of mantle xenoliths found in the Agua Poca volcanic area (Conceição et al 2005;Jalowitzki et al 2010;Fig. 2).…”

Section: And References Therein)mentioning

confidence: 99%

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Lithospheric density structure of the southern Central Andes constrained by 3D data-integrative gravity modelling

Piceda

Scheck‐Wenderoth

Dacal

et al. 2020

Int J Earth Sci (Geol Rundsch)

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The southern Central Andes (SCA) (between 27° S and 40° S) is bordered to the west by the convergent margin between the continental South American Plate and the oceanic Nazca Plate. The subduction angle along this margin is variable, as is the deformation of the upper plate. Between 33° S and 35° S, the subduction angle of the Nazca plate increases from sub-horizontal (< 5°) in the north to relatively steep (~ 30°) in the south. The SCA contain inherited lithological and structural heterogeneities within the crust that have been reactivated and overprinted since the onset of subduction and associated Cenozoic deformation within the Andean orogen. The distribution of the deformation within the SCA has often been attributed to the variations in the subduction angle and the reactivation of these inherited heterogeneities. However, the possible influence that the thickness and composition of the continental crust have had on both short-term and long-term deformation of the SCA is yet to be thoroughly investigated. For our investigations, we have derived density distributions and thicknesses for various layers that make up the lithosphere and evaluated their relationships with tectonic events that occurred over the history of the Andean orogeny and, in particular, investigated the short- and long-term nature of the present-day deformation processes. We established a 3D model of lithosphere beneath the orogen and its foreland (29° S–39° S) that is consistent with currently available geological and geophysical data, including the gravity data. The modelled crustal configuration and density distribution reveal spatial relationships with different tectonic domains: the crystalline crust in the orogen (the magmatic arc and the main orogenic wedge) is thicker (~ 55 km) and less dense (~ 2900 kg/m3) than in the forearc (~ 35 km, ~ 2975 kg/m3) and foreland (~ 30 km, ~ 3000 kg/m3). Crustal thickening in the orogen probably occurred as a result of stacking of low-density domains, while density and thickness variations beneath the forearc and foreland most likely reflect differences in the tectonic evolution of each area following crustal accretion. No clear spatial relationship exists between the density distribution within the lithosphere and previously proposed boundaries of crustal terranes accreted during the early Paleozoic. Areas with ongoing deformation show a spatial correlation with those areas that have the highest topographic gradients and where there are abrupt changes in the average crustal-density contrast. This suggests that the short-term deformation within the interior of the Andean orogen and its foreland is fundamentally influenced by the crustal composition and the relative thickness of different crustal layers. A thicker, denser, and potentially stronger lithosphere beneath the northern part of the SCA foreland is interpreted to have favoured a strong coupling between the Nazca and South American plates, facilitating the development of a sub-horizontal slab.

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Section: Setup Of the Initial Modelmentioning

confidence: 99%

Section: And References Therein)mentioning

confidence: 99%

Lithospheric density structure of the southern Central Andes constrained by 3D data-integrative gravity modelling

Piceda

Scheck‐Wenderoth

Dacal

et al. 2020

Int J Earth Sci (Geol Rundsch)

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“…The territories of South America located south of 33 • S are famous for the occurrence of mantle xenoliths within basaltic lavas and pyroclastic structures. Many of these volcanic fields and xenoliths have been recognized and investigated in the last two decades increasing our knowledge on the general characteristics of the subcontinental lithospheric mantle (SCLM), as well as the detailed structure of the mantle column at several localities (e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]). A complicating factor in the study of these mantle xenoliths is the development of the Pacific subduction, currently represented by the Nazca and Antarctic oceanic plates, below the South American continent.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, over time, volcanism and subduction have contributed in several episodes to the depletion, metasomatism and refertilization of the SCLM, and the results of these processes are commonly archived by mantle xenoliths transported to the surface by the Tertiary-Quaternary magmas. According to various studies, multiple events of metasomatism, depletion and refertilization are widely recorded by xenoliths from the entire Patagonia, and only very rarely are xenoliths here representative of a primary primitive SCLM (e.g., [7,9,[11][12][13][14][16][17][18][19] and references therein).…”

Section: Introductionmentioning

confidence: 99%

Mantle Xenoliths from Huanul Volcano (Central-West Argentina): A Poorly Depleted Mantle Source under Southern Payenia

et al. 2022

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Huanul is a shield volcano with several lava flows hosting mantle xenoliths erupted during the Pleistocene (0.84 ± 0.05 Ma). It is located in the southern part of the Payenia Volcanic Province, which is among the largest Neogene-Quaternary volcanic provinces of South America. The volcanism here has been ascribed as the northernmost expression of the back-arc volcanism of the Andean Southern Volcanic Zone. We present the first petrographic and mineral chemistry study of mantle xenoliths collected from Huanul lavas with the aim of reconstructing directly the mantle source of the Payenia Volcanic Province. Xenoliths are commonly small (<5 cm in radius) but scarcely crossed by basaltic veins. All xenoliths have a fertile lherzolitic modal composition and are equilibrated in the spinel-facies. Most of them exhibit an almost primitive-mantle geochemical affinity, characterized by slightly depleted clinopyroxene REE patterns reproducible by partial melting degrees between 0 and 4% of a PM source. Geothermobarometric P-T estimates of clinopyroxene-orthopyroxene couples form a linear trend between 10 and 24 kbar with constant increase of T from 814 to 1170 °C along a 50–60 mW/m2 geotherm. Evidences of interaction with the host basalts occur as spongy textures in clinopyroxene and reacted spinel, which tend to became more restitic in composition and show chromatographic or complete overprinting of the trace element compositions. The presence of plagioclase and calculated P-T values constrain this melt/rock reaction process between 6 and 14 kbar, during magma ascent, and fit the mantle adiabat model. Calculated melts in equilibrium with the primary clinopyroxenes do not fit the composition of the host basalt and, together with the geothermobarometric estimations, point to an asthenospheric mantle source for the magmatism in southern Payenia. The PM geochemical affinity of the xenoliths of Huanul is an extremely rare finding in the South America lithospheric mantle, which is commonly extensively refertilized by subduction-derived melts.

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“…De todas esas localidades (más de 20), sólo dos contienen peridotitas portadoras de granate: Pali Aike localizada en la Patagonia sur (Skewes y Stern 1979, Douglas et al 1987, Stern et al 1989, Vannucci et al 2002 y Prahuaniyeu, localizada en la Patagonia norte (Ntaflos et al 2001, Bjerg et al 2005, Ntaflos y Bjerg 2006, Bjerg et al 2009. Por su parte, al norte del Río Colorado se indicaron tres localidades con xenolitos del manto (Bertotto 2000, 2002a, 2002b, Jalowitzki et al 2010 y una localidad en el extremo sur de Argentina (Tierra del Fuego, Acevedo y Quartino 2004), en ambos sectores se trata de peridotitas en facies de espinela.…”

Section: Zona De Retroarco Patagónico De Argentinaunclassified

Petrología de los xenolitos del manto alojados en rocas basálticas del Paleoceno-Eoceno en la zona de Paso de Indios, provincia del Chubut

Ponce¹

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Las rocas basálticas eocenas de la región de Paso de Indios (Chubut), son algunas de las varias manifestaciones de basaltos cenozoicos portadores de xenolitos ultramáficos de Patagonia. Los xenolitos analizados presentan una amplia abundancia de harzburgitas y lherzolitas pobres en clinopiroxeno lo que le da un carácter refractario a la columna mantélica del área de estudio. La textura porfiroclástica y la transicional de gruesa a porfiroclástica son las más frecuentes. Las temperaturas de equilibrio están en el orden de los 850 a 1200 °C y las presiones entre 1,1 y 2,2 GPa, indicando una proveniencia de sectores del manto de aproximadamente 40 a 75 km de profundidad. De acuerdo a las composiciones modales, el manto muestreado debajo de Cerro Matilde, Cerro León, Cerro Cortadera y Tapera Marín registra eventos de fusión parcial mayores al 20%; mientras que los xenolitos con grado de empobrecimiento más variable ocurren en Cerro Chenque, donde se encuentran valores de entre 16% y >24%. Tales observaciones son confirmadas por estimaciones de fusión parcial basadas en el #Cr de la espinela. El estudio petrográfico evidencia la ocurrencia de dos esquemas de reacción mineralógica principales debido a la percolación de fluidos/fundidos canalizados: 1) disolución de piroxenos y generación de olivinos nuevos en peridotitas ricas en olivino, y 2) reemplazo de olivinos primarios por ortopiroxeno±clinopiroxeno en peridotitas ricas en ortopiroxeno. La disolución de piroxenos es atribuida a fundidos subsaturados en sílice, mientras que el reemplazo de olivinos primarios por ortopiroxenoclinopiroxeno es concordante con actividad de fundidos saturados en sílice. Las reacciones de desequilibrio identificadas en los xenolitos comprenden: la reacción de ortopiroxeno en contacto con basalto alojante y coronas de reacción en ortopiroxeno, clinopiroxeno y espinelas asociadas a venas de vidrio. Tales rasgos están aparentemente relacionados a la inyección de fundido, probablemente durante la interacción con el basalto alojante en el transcurso de su ascenso a la superficie. El comportamiento de los elementos de tierras raras sugiere eventos de empobrecimiento marcados y enriquecimientos metasomáticos variables por agentes con características similares a fundidos alcalinos (tipo OIB), ultra-alcalinos (tipo kimberlitas) y de composición similar a un fundido en equilibrio con hornblenda. Es notable la impronta de ambiente de subducción en dichos fundidos.

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Evolução geoquímica de peridotitos e piroxenitos do Manto Litosférico Subcontinental do vulcão Agua Poca, Terreno Cuyania, Argentina

Cited by 9 publications

References 2 publications

Lithospheric density structure of the southern Central Andes constrained by 3D data-integrative gravity modelling

Lithospheric density structure of the southern Central Andes constrained by 3D data-integrative gravity modelling

Mantle Xenoliths from Huanul Volcano (Central-West Argentina): A Poorly Depleted Mantle Source under Southern Payenia

Petrología de los xenolitos del manto alojados en rocas basálticas del Paleoceno-Eoceno en la zona de Paso de Indios, provincia del Chubut

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