DOI: 10.1016/j.palaeo.2013.07.010
论文题名: Shaking a methane fizz: Seismicity from the Araguainha impact event and the Permian-Triassic global carbon isotope record
作者: Tohver E. ; Cawood P.A. ; Riccomini C. ; Lana C. ; Trindade R.I.F.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2013
卷: 387 起始页码: 66
结束页码: 75
语种: 英语
英文关键词: Carbon isotope excursion
; Impact event
; Methane
; Permian-Triassic mass extinction
; Seismicity
英文摘要: The Late Permian and Early Triassic periods are marked by large fluctuations in the carbon isotope record, but the source(s) of the disturbance to the global carbon cycle and the link to the end-Permian mass extinction are widely debated. This contribution explores the possible isotopic effects of an impact event into the hydrocarbon-rich rocks of the Paraná-Karoo Basin. Recent U-Pb and 40Ar/39Ar dating of the 40km Araguainha impact structure of central Brazil reveals an age of 254.7±2.5Ma (2σ error) for this event. The calculated energy (105-106MT of TNT equivalent) released by this impact is less than threshold values of 107-108MT TNT equivalent for global mass extinctions. Thus, the Araguainha crater is unlikely to have been the cause of the end-Permian biotic crisis. However, the combined seismic effects from the impact itself and the post-impact collapse of the 20-25km diameter transient crater to its present 40km diameter would result in large magnitude earthquakes (Mw 9.3-10.5) and tsunamis in the shallow marine Paraná-Karoo Basin. Slope failure and sediment liquefaction are predicted to have occurred within a 700-3000km radius of the crater, causing large-scale release of methane from organic-rich sediments of this basin, including the oil shale horizons of the Iratí Formation. New geological evidence for seismicity in the Paraná Basin at the time of impact is presented, together with a compilation of existing carbon isotope data from the Paraná Basin, which demonstrate a widespread pattern of disturbance consistent with the release of methane. These two datasets suggest that both seismicity and methane release took place within ca.1000km of the impact site, with mass balance calculations suggesting ca. 1600GT of methane were released into the atmosphere at this time. Methane release at this scale would have significant climate effects and would contribute to a sharp (<1ka) negative shift in δ13C values at the time of the impact, which should be distinguishable from the more gradual shift over 0.5-1Ma caused by contemporaneous intrusion of the Siberian traps. © 2013 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69631
Appears in Collections: 过去全球变化的重建
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作者单位: School of Earth and Environment, University of Western Australia, Australia; St. Andrews University, Scotland, United Kingdom; Universidade de São Paulo, Brazil; Universidade Federal de Ouro Preto, Brazil
Recommended Citation:
Tohver E.,Cawood P.A.,Riccomini C.,et al. Shaking a methane fizz: Seismicity from the Araguainha impact event and the Permian-Triassic global carbon isotope record[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2013-01-01,387