期刊
JOURNAL OF SOUTH AMERICAN EARTH SCIENCES
卷 111, 期 -, 页码 -出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jsames.2021.103433
关键词
Extinction; Paleovertebrate; Absolute age; Upper Triassic; Palynomorphs; Onslow microflora; Dinosaurs
资金
- Agencia Nacional de Promocion Cientifica y Tecnologica [PICT 2015-1312, PICT 2015-2074]
- Conicet [PIP 190]
The Late Triassic period captures significant life crises related to environmental changes during the Pangea breakup, with the Ischigualasto Formation recording the Triassic Dinosaur Diversification Event and key terrestrial environmental shifts. This period of environmental modification and faunal turnover is precisely dated to about 228.91 +/- 0.14 Ma, providing insights into the series of environmental-biological disturbances leading to the end of the Triassic.
The Late Triassic represents records many of the most critical biotic crises in life-history (from Carnian to the end-Triassic extinction, ETE). Some hypotheses propose that these life changes were linked with shifts in the environmental setting during the initial stages of the Pangea breakup. These crises were likely not sudden events but a series of step-changes that reached their peak at the end of the Triassic. The Carnian-Norian Ischigualasto Formation is a world-renown terrestrial sequence that records both the Triassic Dinosaur Diversification Event (DDE) and at least one crucial terrestrial environmental and biotic turnover. A notable increase in humidity and volcanism was the setting of critical faunal replacement represented by the passage of the HyperodapedonExaeretodon-Herrerasaurus to Exaeretodon tetrapod biozones. That environmental modification, together with the paleofaunistic turnover, has been accurately constrained by a new high-precision CA-TIMS U/Pb zircon age of 228.91 +/- 0.14 Ma obtained from a tuff layer located in the exact stratigraphic position of the major bioticpaleoenvironmental disturbance in the middle part of the Valle de la Luna Member, at similar to 310 m from the base of the Ischigualasto Formation. Palynological assemblages containing the first records in westernmost Gondwana of European Tethyan and Onslow palynological species are also recognized close to the dated tuff level. Thus, this age is the first isotopic record for the Onslow Microflora diagnostic species in Gondwana. Moreover, the CA-TIMS date promotes a discussion about the accurate chronostratigraphic position for the beginning (after the Carnian Pluvial Event) of a series of environmental-biological disturbances that culminated at the end of the Triassic.
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