A Unitary Association-based conodont biozonation of the Smithian-Spathian boundary (Early Triassic) and associated biotic crisis from South China.

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License: CC BY 4.0
Serval ID
serval:BIB_6283D0E88903
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
A Unitary Association-based conodont biozonation of the Smithian-Spathian boundary (Early Triassic) and associated biotic crisis from South China.
Journal
Swiss journal of palaeontology
Author(s)
Leu M., Bucher H., Vennemann T., Bagherpour B., Ji C., Brosse M., Goudemand N.
ISSN
1664-2384 (Electronic)
ISSN-L
1664-2376
Publication state
Published
Issued date
2022
Peer-reviewed
Oui
Volume
141
Number
1
Pages
19
Language
english
Notes
Publication types: Journal Article
Publication Status: ppublish
Abstract
The Smithian-Spathian boundary (SSB) crisis played a prominent role in resetting the evolution and diversity of the nekton (ammonoids and conodonts) during the Early Triassic recovery. The late Smithian nektonic crisis culminated at the SSB, ca. 2.7 Myr after the Permian-Triassic boundary mass extinction. An accurate and high-resolution biochronological frame is needed for establishing patterns of extinction and re-diversification of this crisis. Here, we propose a new biochronological frame for conodonts that is based on the Unitary Associations Method (UAM). In this new time frame, the SSB can thus be placed between the climax of the extinction and the onset of the re-diversification. Based on the study of new and rich conodont collections obtained from five sections (of which four are newly described here) in the Nanpanjiang Basin, South China, we have performed a thorough taxonomical revision and described one new genus and 21 new species. Additionally, we have critically reassessed the published conodont data from 16 other sections from South China, and we have used this new, standardized dataset to construct the most accurate, highly resolved, and laterally reproducible biozonation of the Smithian to early Spathian interval for South China. The resulting 11 Unitary Association Zones (UAZ) are intercalibrated with lithological and chemostratigraphical (δ <sup>13</sup> C <sub>carb</sub> ) markers, as well as with ammonoid zones, thus providing a firm basis for an evolutionary meaningful and laterally consistent definition of the SSB. Our UAZ <sub>8,</sub> which is characterized by the occurrence of Icriospathodus ex gr. crassatus, Triassospathodus symmetricus and Novispathodus brevissimus, is marked by a new evolutionary radiation of both conodonts and ammonoids and is within a positive peak in the carbon isotope record. Consequently, we propose to place the SSB within the separation interval intercalated between UAZ <sub>7</sub> and UAZ <sub>8</sub> thus leaving some flexibility for future refinement and updating.
The online version contains supplementary material available at 10.1186/s13358-022-00259-x.
Keywords
Conodonts, Smithian–Spathian boundary, South China, Unitary associations
Pubmed
Open Access
Yes
Create date
05/12/2022 15:24
Last modification date
23/01/2024 7:26
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