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

Abstract

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...

Tracking voluminous Permian volcanism of the Choiyoi Province into central Antarctica

“…Permian volcanic and plutonic rocks of the Choiyoi Province were emplaced during contraction of the San Rafael event and continued through the initial stage of extension at ca. 265 Ma (Sato et al, 2015;Rocha-Campos et al, 2011;Spalletti and Limarino, 2017;Kleiman and Japas, 2009). The temporal and geochemical signature of this event is present in our data from central Antarctica and indicates they are sourced from the Choiyoi Province or correlative Gondwana arc rocks of Patagonia, Antarctic Peninsula, and/or Thurston Island.…”

“…1) is principally characterized by widespread Permian subduction-related andesitic to rhyolitic volcanic rocks (primarily ignimbrites) erupted over an area of ~1.7 Mkm 2 of Chile and Argentina, with an average thickness of 700 m emplaced between ca. 282 and 251 Ma with a major flare-up at 269-263 Ma (e.g., Rocha-Campos et al, 2011;Kimbrough et al, 2016;Spalletti and Limarino, 2017). The plutonic components of the Choiyoi are broadly defined as tonalitiesgranodiorites to granites emplaced between 286 and 247 Ma (e.g., Sato et al, 2015).…”

“…Definitive volume estimates for the Choiyoi Province, volcanic and plutonic, are lacking but there is broad consensus that the Choiyoi Province represents the largest silicic magmatic event in southwestern Gondwana (e.g., Rocha-Campos et al, 2011;Sato et al, 2015;Kimbrough et al, 2016;Spalletti and Limarino, 2017). The age of the Choiyoi Province (ca.…”

“…The age of the Choiyoi Province (ca. 286-247 Ma) overlaps with the Permian-Triassic and End Guadalupian mass extinction events, carbon isotope excursions, and a shift from icehouse to greenhouse conditions associated with increases in atmospheric greenhouse gases (Spalletti and Limarino, 2017). For these reasons the Choiyoi Province has been proposed as a major source of volcanogenic greenhouse gases (e.g., CO 2 ) during volcanism and magmatism that heated organic-rich Paleozoic sedimentary rocks, releasing additional greenhouse gases and contributing to Permian global warming and environmental crises (Kimbrough et al, 2016;Spalletti and Limarino, 2017;Henry et al, 2009;Henry, 2013;Hermann et al, 2011;Luppo et al, 2018;Limarino et al, 2014).…”

“…1; Rocha-Campos et al, 2011;Sato et al, 2015;Castillo et al, 2016;Elliot et al, 2016Elliot et al, , 2017McKay et al, 2016). In South America, Permian arc volcanism resulted in exceptionally high volume silicic volcanism of the Choiyoi Province (estimated volume of ~1.3 Mkm 3 ) that may have contributed to global climate change, Permian mass extinctions and biotic crises (e.g., Henry et al, 2009;Hermann et al, 2011;Henry, 2013;Limarino et al, 2014;Kimbrough et al, 2016;Spalletti and Limarino, 2017;Luppo et al, 2018). Correctly correlating Permian volcanic deposits in southwestern Gondwana to the Choiyoi Province, therefore, is critical to determining the distribution and timing of one of the largest silicic provinces along the paleo-Pacific margin of Gondwana and its relationship to Permian global warming and environmental degradation.…”