Data di Pubblicazione:
2010
Citazione:
The latest Permian mass extinction in the Alborz Mountains (North Iran) / L. Angiolini, A. Checchoni, M. Gaetani, R. Rettori. - In: GEOLOGICAL JOURNAL. - ISSN 0072-1050. - 45:2-3(2010), pp. 216-229. [10.1002/gj.1203]
Abstract:
The Elikah River section in the Alborz Mountains (North Iran) is a fossiliferous, continuous, marine section spanning the Permian–Triassic
(P–T) boundary interval. Sixty-eight taxa of brachiopods, foraminifers and algae have been collected bed-by-bed from the topmost 36 m of the
Nesen Formation and the basal 2 m of the Elikah Formation, across the P–T boundary that is located in the basal metre of the latter formation.
Forty-six of these taxa from 62 samples have been considered for statistical analyses to unravel the pattern of extinction. First, their range
extensions have been determined, which should be added to the highest stratigraphic occurrence of each taxon to identify the extinction level
within a certain confidence interval (95%). Then the pattern of the extinction has been analysed, plotting the stratigraphic abundance versus
last occurrence below the extinction horizon. The resulting pattern is of a sudden extinction occurring 30 cm below the biostratigraphically
defined base of the Triassic. The confidence interval (95%) for the mass extinction is 30 cm thick. As predicted by the ‘Signor–Lipps effect’,
brachiopod last occurrences underestimate the time of extinction, as their abundance is below 15%. Therefore, also in North Iran located at
equatorial palaeolatitudes along the southern shore of the Palaeotethys Ocean, the pattern of the latest Permian mass extinction is abrupt as
observed in South China, in peri-Gondwana and in the Southern Alps. One of the most plausible mechanisms of the latest Permian sudden
mass extinction could have been the emissions of tholeiitic magmas (Siberian Traps), which could have caused greenhouse gases emission
into the atmosphere and thus global warming and ozone depletion, triggering the crisis (Svensen et al. 2008). Copyright # 2010 John Wiley &
Sons, Ltd.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
Brachiopods; Confidence interval; Extinction; Foraminifers; Iran; Pattern of extinction; Permian-triassic boundary
Elenco autori:
L. Angiolini, A. Checchoni, M. Gaetani, R. Rettori
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