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Prior to their extinction at the Triassic-Jurassic boundary, conodonts were relatively diverse and abundant during Norian time. The great faunal turnovers at the base of the Norian and the base of the Alaunian (Middle Norian) confirm that the end-Triassic mass extinction was protracted through Late Triassic time rather than a single event. Norian conodonts also display obvious geographic distribution. Thus, investigation of Norian conodonts is not only of biostratigraphic significance, but it will elucidate the end Triassic mass extinction event as well as Late Triassic palaeobiogeography. Lacian (Early Norian) and Alaunian faunas appear to have spread extensively through Tibetan terranes of the Eastern Tethys, yet evidence of a continuous Lacian to Alaunian conodont succession as well as faunal turnover at the base of the Alaunian is sparse. Our biostratigraphic investigation of carbonate deposits of the Mopanshan area of the South Qiangtang Terrane has yielded abundant Norian conodonts. The Lacian Ancyrogondolella uniformis-Norigondolella hallstattensis Fauna and the Alaunian Mockina postera-Norigondolella steinbergensis Fauna are well-represented in the study region. The Norian conodont succession of the Eastern Tethys may be correlative with that of the Western Tethys and Eastern Pacific. The obvious geographic distribution provides evidence that the Indus-YarluZangbo Suture Zone (IYZSZ) separated Eastern Tethys into northern Tethys and southern Tethys realms. Norian conodonts are less abundant and diverse in the southern Tethys realm relative to the northern (or peri-Gondwana) Tethys. The Himalaya Terrane in the south belonged to southern Tethys whereas the Lhasa and the South Qiangtang terranes were part of the northern Tethys. Moreover, the absence of Norigondolella steinbergensis from the southern Tethys seemed to differentiate this realm from the northern Tethys. • Early-Middle Norian conodonts aredescribedfor the first time from Qiangtang, Tibet 2) the recovered Norian conodonts necessitate reassessment of the age of the deposits 3) the Norian conodont succession is correlative with well-established successions from Western Tethys and Eastern Pacific • Norian conodonts help elucidate the palaeobiogeography of Northern Tethysand peri-Gondwana Tethys realms [ABSTRACT FROM AUTHOR]

The Lhasa Terrane of Tibet is critical to understanding Early Triassic crustal convergence of Gondwana and Eurasia. However, its palaeo-position during this period remains obscure. This paper considers the disputed tectonic nature of the Lhasa Terrane during Triassic time. The debate has taken the form of two schools of thought regarding the Lhasa Terrane. One holds that the terrane was a stable carbonate platform during Triassic time. The opposing view maintains that the Lhasa Terrane occupied a compressional orogenic belt. These contrasting explanations stem mainly from the absence of a sedimentary record, especially in the southern part of the Lhasa Terrane of Tibet. We report on results of a biostratigraphic investigation of a dolomite unit considered to be of Guadalupian age in the Comai area, southern Lhasa Terrane. This work yielded the ellisonid conodont species Pachycladina rendona n. sp. Wu and Ji suggesting an Early Triassic age and a low latitude depositional setting of the dolomite. Further, these findings favor correlation of the dolomite with the upper member of the Upper Permian to Lower Triassic Mujiuco Formation. Results of the present study, especially the newly collected Pachycladina fauna, suggest that the Lhasa Terrane was an element of a low-latitude carbonate platform that had separated from Gondwana during the Early Triassic. It is hoped that our findings will promote further research of the Triassic sedimentary history and paleogeographic evolution of the Lhasa Terrane. • The ellisonid Pachycladina fauna has been recovered from the southern Lhasa Terrane. • The Pachycladina fauna places the Lhasa Terrane at low latitude during the Induan. • The western Lhasa Terrane was a carbonate platform setting during the Early Triassic. [ABSTRACT FROM AUTHOR]