The neopaleozoic of the Sierra de Castaño (Andean Cordillera Frontal, San Juan, Argentina): Tectonic and paleoenviromental reconstruction.

Busquets, Pedro; Limarino, Carlos Óscar; Cardó, Raúl; Méndez-Bedia, I.; Gallastegui, G.; Piñol, Ferrán Colombo; Heredia, N.; Césari, Silvia N.

doi:10.5027/andgeov40n1-a08

Cited by 2 publications

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“…This magmatism, known as the Choiyoi Magmatic Province, is characterised by a widespread and thick record of volcanic and volcaniclastic rocks and was developed after a phase of orogenic deformation (Mpodozis and Kay, 1992;Busquets et al, 2013) occurred in the early Permian, between 290 and 280 Ma (Llambías andSato, 1990, 1995;Pérez and Ramos, 1990). The Choiyoi cycle consists of two magmatic episodes and shows an evolutionary trend from calc-alkaline to anorogenic compositions (Sato et al, 2015).…”

Section: The Choiyoi Magmatic Province In Western Gondwanamentioning

confidence: 99%

“…In the western Gondwana arc-related basins, late Carboniferous-early Permian carbonate rocks of the Río Blanco basin (San Ignacio Formation) are unconformable covered by volcanic breccias, ignimbrites and lava f lows belonging to the Choiyoi volcanism (Busquets et al, 2007(Busquets et al, , 2013. Far north, in the arc-related Arizaro depocenter, early-mid Permian carbonate beds (mudstones, stromatolites, wackestones and grainstones) are associated with pyroclastic f low deposits (Galli et al, 2010).…”

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The Choiyoi magmatism in south western Gondwana: implications for the end-permian mass extinction - a review

Spalletti

Limarino

2017

andgeo

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ABSTRACT. The end of the Permian period is marked by global warming and the biggest known mass extinction on Earth. The crisis is commonly attributed to the formation of large igneous provinces because continental volcanic emissions have the potential to control atmospheric carbon dioxide (CO 2 ) levels and climate change. We propose that in southwestern Gondwana the long-term hothouse Permian environmental conditions were associated with the development of the Choiyoi magmatism. This large igneous province was developed between the Cisuralian and the early Triassic. It covers an area estimated at 1,680,000 km 2 with an average thickness of 700 m, so that the volume of effusive and consanguineous rocks is estimated at 1,260,000 km 3 . Towards the western sector of the study region, a major overlap exists between the regional development of the Choiyoi magmatism and the Carboniferous sedimentary basins, which include paralic and continental deposits with intercalations of peat and coal beds. Commonly, these upper Palaeozoic deposits accumulated on a thick substrate composed of Cambro-Ordovician carbonates and Ordovician to Devonian terrigenous sedimentary rocks characterised by a large proportion of dark organic-rich shales and turbidite successions. While extensive volcanism released large masses of carbon dioxide into the Permian atmosphere, the heating of Palaeozoic organic-rich shales, peat and carbonates by ascending magma led to CO 2 and CH 4 gas generation in sufficient volumes to amplify the major climatic change. The analysis of the almost continuous record of Permian redbeds in the Paganzo basin, where the Choiyoi magmatism is not recorded, allowed us to recognize two main pulses of strong environmental desiccation, one at the Cisuralian and the second around the end-Permian. These two drastic climatic crisis are attributed to peaks of CO 2 and CH 4 outbursts to the atmosphere and related collateral effects, such as acid rain, impoverishment of soils and increase in forest-fire frequency. We propose that the combination of these multiple mechanisms triggered the decline of biodiversity in southwestern Gondwana and caused the end-Permian extinction of most of the Glossopteridales. RESUMEN. El magmatismo Choiyoi en el sudoeste de Gondwana: su implicancia en la extinción en masa del Pérmico tardío -una revisión. El final del Pérmico está caracterizado por un proceso de calentamiento global que llevó a la mayor extinción en masa registrada en la Tierra. Esta crisis se atribuye comúnmente a la generación de grandes provincias ígneas en ámbito continental, cuyas emisiones volcánicas han controlado los niveles de CO 2 en la atmósfera y el consecuente cambio climático. En este trabajo se propone que las condiciones fuertemente cálidas (hothouse) del Pérmico en el sudoeste de Gondwana estuvieron asociadas con el desarrollo del magmatismo Choiyoi. Esta provincia ígnea, que se desarrolló durante el lapso Cisuraliano-Triásico temprano, cubrió un área estimada en 1.680.000 km 2 con un espesor medio de 700 m, de modo...

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Section: The Choiyoi Magmatic Province In Western Gondwanamentioning

confidence: 99%

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confidence: 99%

The Choiyoi magmatism in south western Gondwana: implications for the end-permian mass extinction - a review

Spalletti

Limarino

2017

andgeo

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Structure of the Andean Palaeozoic basement in the Chilean coast at 31º 30’ S: Geodynamic evolution of a subduction margin

Garcı́a-Sansegundo

Farias

Heredia

et al. 2014

Journal of Iberian Geology

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The Palaeozoic basement outcropping to the north of Los Vilos is formed by (i) the Choapa Metamorphic Complex (ChMC) made of metabasites (amphibolites and retrogressed eclogites), fine-grained gneisses, schists and quartz-schists, and (ii) the meta-sedimentary and sedimentary rocks of the Arrayán and Huentelauquén formations respectively. Near Huentelauquén (31º 30' S), the ChMC has been affected by three deformation episodes related with the Gondwanan orogenic episode. The first episode (D1) is represented by a foliation (S1) formed under HP-LT metamorphic conditions and preserved in syn-D2 garnet and albite porphyroblasts. A generalised crenulation cleavage (S2) was developed under pressure decreasing conditions during the second deformation episode (D2). This episode is responsible for the exhumation of the ChMC, which took place through an east-directed reverse fault system that thrusts the ChMC over the Arrayán Formation, producing more than 20 km shortening. The third deformation episode (D3) is represented by a west-verging kilometre-scale anticline, with a thrust in its reverse limb (Las Caldas thrust). Minor folds and crenulations are also associated with D3. D3 structures affect the ChMC and the Arrayán Formation and are responsible for the overturning of the D2 thrusts. The Huentelauquén Formation, late Carboniferous -Permian in age, is the latest unit deformed by Gondwanan structures. The characterisation of the structure and its relation to metamorphism in the study area, lead to propose a geodynamic model related with an Andean type non-collisional orogenic process, for the Gondwanan orogenic episode of the Andes at this latitude.Keywords: Gondwanan structure, tectono-metamorphic evolution, Choapa Metamorphic Complex, Chile, system thrust Resumen El basamento Paleozoico que aflora al norte de Los Vilos está constituido por (i) el Complejo Metamórfico de Choapa (CMCh), formado por esquistos, cuarzo esquistos, gneises de grano fino y metabasitas (anfibolitas y retroeclogitas) y (ii) rocas metasedimentarias y sedimentarias de las formaciones Arrayán y Huentelauquén respectivamente. En los alrededores de Huentelauquén (31º 30' S), las rocas del CMCh han sido afectadas por tres fases de deformación (D1, D2, D3), relacionadas con el episodio orogénico Gondwánico. Las estructuras D1 están representadas por una foliación tectónica (S1), que se desarrolló bajo condiciones metamórficas de AP-BT y que está preservada en porfiroblastos de granate y albita, crecidos durante el segundo episodio de deformación. Durante la fase de deformación D2 se produce una bajada de la presión y se desarrolla la foliación regional S2. La foliación S2 es contemporánea con el emplazamiento de un dúplex de cabalgamientos dirigidos hacia el este que exhuman el CMCh y lo sitúan sobre las series epimetamórficas de la Formación Arrayán. El acortamiento que producen las estructuras D2 es superior a 20 km. La tercera fase de deformación está representada por pliegues y crenulaciones asociados a un antiforme de escala kilométric...

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The neopaleozoic of the Sierra de Castaño (Andean Cordillera Frontal, San Juan, Argentina): Tectonic and paleoenviromental reconstruction.

Cited by 2 publications

References 14 publications

The Choiyoi magmatism in south western Gondwana: implications for the end-permian mass extinction - a review

The Choiyoi magmatism in south western Gondwana: implications for the end-permian mass extinction - a review

Structure of the Andean Palaeozoic basement in the Chilean coast at 31º 30’ S: Geodynamic evolution of a subduction margin

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