Lower-Middle Triassic Conodonts of Ganheqiao Section,Wangmo County,Guizhou Province
Liang Lei
Wu Kui
Tian Li
Tong Jinnan
Abstract：The establishment of modern ecosystem in Early Triassic is challenging and subject to frequent fluctuation of environment,thus a refined time scale is demanded to explore its process and mechanism.Although conodonts are often used as index fossils in the correlation and division of Paleozoic and Early Mesozoic marine strata,the international classification and comparison criteria for multiple stages and substages of the Early-Middle Triassic have been pending.Some candidate index fossils have yet to be further tested by regional and global correlation.The deep-water strata were well developed in the Lower-Middle Triassic at the Ganheqiao Section in Wangmo County of Guizhou.In this paper,a systematic study of conodont taxonomy and stratigraphy was carried out on the samples near the Lower-Middle Triassic boundaries of the section.A total of 29 species in 15 genera were identified and 10 conodont zones were recognized,namely Neospathodus dieneri Zone,Novispathodus waageni Zone,Guangxidella bransoni Zone,Novispathodus pingdingshanensis Zone,Icriospathodus crassatus Zone,Triassospthodus homeri Zone,Triassospthodus triangularis Zone,Triassospthodus sosioensis Zone,Chiosella timorensis Zone,Nicoraella germanica Zone in ascending order.According to the distribution of conodonts in this section and the comparison with other sections,it is supported that the first occurrences of conodonts Novispathodus waageni,Novispathodus pingdingshanensis and Chiosella timorensis are used as the criteria for the Indian-Olenekian,Smithian-Spathian and Lower-Middle Triassic boundaries,respectively.In the past few years,multiple layers of marine reptiles and diverse arthropod fossils have been reported in the Triassic in the Wangmo area,indicating a multi-stage evolution of marine ecosystems.The high-resolution biostratigraphic framework established in this paper provides key evidence to calibrate the build-up time of modem marine ecosystems in study area.
Keywords：conodontSmithian-Spathian boundaryLower-Middle Triassic boundarygeobiology
Publication Date：2025-01-14
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：14( 19-32 )