中国科学院南京地质古生物研究所机构知识库

Reinvestigation of the Devonian-Carboniferous boundary sequence in Yalai village, Nyalam County, southern Tibet, enabled the recovery of well-preserved palynomorphs and conodonts in the Yali section. Based on quanti-tative analysis of the relative abundances of various palynomorphs, two palynological assemblages are recog-nized in the Famennian-Tournaisian boundary beds of the Yali section. In ascending order, they are the Retispora lepidophyta???Verrucosisporites irregularis (LI) assemblage and the Retispora lepidophyta???Vallatisporites vallatus (LV) assemblage. Both assemblages are tentatively correlated with the Famennian LN Biozone of Western Europe because of the appearance of Retispora lepidophyta and other index spores such as Vallatisporites verrucosus, Vallatisporites pusillites, Indotriradites explanatus, and Densosporites spitsbergensis in both palynologi-cal assemblages. The lower limestones of the Yali Formation yield biostratigraphic markers for the Devonian -Carboniferous boundary, including the conodont Siphonodella sulcata and Protognathodus kockeli, correlated with the VI Biozone from Western Europe and parts of Gondwana. The upper Lazhabu Member of the Yali Forma-tion yielded Retispora lepidophyta, Vallatisporites vallatus, and Vallatisporites pusillites of the LV Biozone, indicating that some typical palynomorphs elements of the LN Biozone of Western Europe persisted into Tournaisian in southern Tibet. ?? 2022 Elsevier B.V. All rights reserved.