Trace-element and Sr, Nd, Pb, and O isotopic composition of Pliocene and Quaternary alkali basalts of the Patagonian Plateau lavas of southernmost South America

Stern, Charles R.; Frey, Frederick A.; Futa, Kiyoto; Zartman, Robert E.; Peng, Zicheng; Kyser, T. Kurtis

doi:10.1007/bf00321486

Cited by 174 publications

(138 citation statements)

References 30 publications

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“…Stern et al (1990) reported the chemistry and 87 Sr/ 86 Sr isotopic ratio of a basalt from 'Los Volcanes', having similar values as the analysis reported in the present work. 18.142' 36° 20.270' 36° 23.748' 36° 23.130' 36° 18.673' 36° 18.153' 36° 23.226' 36° 20.076' 36° 29.591' 36° 29.516' 69° 19.884' 69° 23.733' 69° 03.493' 69° 21.010' 69° 17.246' 69° 04.691' 69° 02.488' 69° 19.471' 69° 16.503' 69° 16.880 Sr isotopic ratio in the 9 samples indicates a narrow range in their values, between 0.703766 and 0.704288 (Table 1).…”

Section: Fluid-fluid Relationship Groundmasssupporting

confidence: 88%

Volcanic stratigraphy and evidence of magma mixing in the Quaternary Payun Matru volcano, andean backarc in western Argentina

Hernando¹,

Llambías²,

González³

et al. 2012

Andgeo

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AbStRAct. The Payún Matrú Volcanic Field is located in the Payenia Basaltic Province of the recent back-arc of western Argentina (35°S-38°S). This province is younger than 5 Ma, and most of its volcanic activity took place since 2 Ma. The Payún Matrú Volcanic Field contains two composite volcanoes, Payún Matrú and Payún Liso, and two basaltic fields in an E-W oriented zone, located east and west of the Payún Matrú volcano. Payún Matrú is the largest volcano of this volcanic field, and consists of a shield-shaped edifice with a circular summit caldera of 8 km in diameter. The composition of both composite volcanoes is alkaline and predominantly trachytic, having also minor intermediate lavas.The basaltic fields consist of basalts and trachybasalts, with clinopyroxene and abundant olivine as phenocrysts and also in the groundmass. Textures indicating mixing and mingling processes, such as dusty plagioclases along with clear ones, biotite replaced by anhydrous minerals and two groundmasses with a fluid-fluid relationship, are common in the early pre-caldera stage of Payún Matrú and some post-caldera lavas. The latest post-caldera lavas are trachytic, with clean sanidine phenocrysts without disequilibrium textures. A remarkable characteristic of the Payún Matrú Volcanic Field is the fact that the Payún Matrú caldera is surrounded by basaltic fields at its base, while no basalts were erupted in the caldera region. We propose that the absence of basaltic lavas in the Payún Matrú volcano is due to the presence of a magmatic chamber below it, and that the mafic magmas rising from deeper levels were unable to erupt without interaction with more evolved melts. Intermediate hybrid magmas produced as a consequence of magma mixing and mingling between basaltic and trachytic magmas, are present in the early and mid-history of Payún Matrú volcano. We present here new information about the Quaternary Payún Matrú Volcanic Field derived from field work, petrography, and major element geochemistry and 87 Sr/ 86 Sr isotopic ratios. For the first time a detailed map of the Payún Matrú Volcanic Field and its volcanic stratigraphy, primarily based on field observations, are presented. RESuMEn. Estratigrafía volcánica y evidencia de mezcla de magmas en el volcán Payún Matrú del cuaternario, en el retroarco andino de Argentina occidental. El Campo Volcánico Payún Matrú está localizado en la Provincia Basáltica Payenia, en el retroarco reciente al oeste de Argentina (35°S-38°S). Esta provincia es más joven que 5 Ma, y la mayor parte de su actividad volcánica tuvo lugar desde hace 2 Ma. El Campo Volcánico Payún Matrú contiene dos volcanes compuestos, el Payún Matrú y el Payún Liso, así como dos campos basálticos en una franja E-W, ubicados al este y oeste del Payún Matrú. El Payún Matrú es el volcán más grande de este campo volcánico, y consiste en un edificio en forma de escudo con una caldera circular en su cúspide de 8 km de diámetro. La composición de ambos volcanes compuestos es alcalina y predominantemente traquítica, con menor...

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Section: Fluid-fluid Relationship Groundmasssupporting

confidence: 88%

Volcanic stratigraphy and evidence of magma mixing in the Quaternary Payun Matru volcano, andean backarc in western Argentina

Hernando¹,

Llambías²,

González³

et al. 2012

Andgeo

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“…These episodes are characterized by the eruption of alkali basalts [5] that in many outcrops contain mantle xenoliths. Ultrama c xenoliths are reported in di erent locations in Patagonia: mantle inclusions from the Comallo Region (Río Negro province) and Los Adobes (Chubut province) were rstly discussed by Gelós and Hayase [6].…”

Section: Introductionmentioning

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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“…From the previous discussion, the Tres Picos Prieto basaltic lavas represent an intermediate case between subduction-related and within-plate volcanism. This kind of volcanic rocks has similarities with the 'transitional' type defined by Stern et al (1990) in southern South America, which display characteristics between the cratonic basalts (OIBtype magmas) and the arc basalts. Some examples of this particular type of basalts in Patagonia were described in Cenozoic rocks from Meseta de la Muerte (Gorring et al, 1997), from Meseta de las Vizcachas, Camusú Aike (D'Orazio et al, 2004(D'Orazio et al, , 2005, from Cerro Ante (Bruni et al, 2008) and from the Zeballos Volcanic sequence (Espinoza et al., 2010).…”

Section: Fig 4 Geochemical Classification and Tectonic Diagrams Formentioning

confidence: 73%

“…In this context, basalts of transitional type could be the consequence of a decrease in the amount of incompatible elements derived from the dehydratation of the subducting slab together with the consistent lower degree of partial melting that determines a change from arc to back-arc volcanism (e.g., Hickey-Vargas et al, 1986Stern et al, 1990). This is in accordance with the geological framework, as Tres Picos Prieto lavas uncomformably overly Jurassic to Lower Cretaceous mesosilicic and acid volcanic rocks that are typical of arc settings.…”

Section: Fig 4 Geochemical Classification and Tectonic Diagrams Formentioning

confidence: 99%

Paleomagnetism and geochemistry from the Upper Cretaceous Tres Picos Prieto locality (43ºS), Patagonian Plateau Basalts

Zaffarana¹,

Lagorio²,

Somoza³

2012

Andgeo

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ABSTRACT.A paleomagnetic study on nine samples from lavas from the Upper Cretaceous Tres Picos Prieto locality (43º50'S and 70º3'W), Patagonian Plateau Basaltic Province, revealed that a ca. 300 m thick pile of basalts accumulated during three discrete (i.e., temporally separated) volcanic episodes. The chemistry of these lavas shows characteristics compatible with both subduction and intraplate magmatism, with the former having a more important contribution in the younger lavas. Overall, we interpret these rocks to be transitional basalts generated in a supra-subduction environment. The Late Cretaceous to Cenozoic Patagonian Plateau Basaltic Province crops out from eastern Patagonia to the cordillera, and their genesis have been associated with different tectonic processes, even for spatially separated rocks of the same age. Considering that the development of the magmatic province is contemporary with the stage of westward drift of South America, we propose that magma generation and upwelling due to rapidly shearing asthenosphere inducing circulatory flow associated to asperities in the lithosphere-asthenosphere interface (shear-driven upwelling) can be evaluated as a further potential mechanism to account for many outcrops of these backarc to intraplate lavas.

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Trace-element and Sr, Nd, Pb, and O isotopic composition of Pliocene and Quaternary alkali basalts of the Patagonian Plateau lavas of southernmost South America

Cited by 174 publications

References 30 publications

Volcanic stratigraphy and evidence of magma mixing in the Quaternary Payun Matru volcano, andean backarc in western Argentina

Volcanic stratigraphy and evidence of magma mixing in the Quaternary Payun Matru volcano, andean backarc in western Argentina

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

Paleomagnetism and geochemistry from the Upper Cretaceous Tres Picos Prieto locality (43ºS), Patagonian Plateau Basalts

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