Kungurian (Late Cisuralian) fusuline fauna from the Cuozheqiangma area, northern Tibet and its palaeobiogeographical implications

摘要

A fusuline fauna of seven species belonging to six genera from the lower part of the Lugu Formation in the Qiangtang Block, Tibet, is described for the first time. This fauna is assigned to the middle Kungurian based on the dominance of Cancellina primigena (Hayden). Biogeographically, the fauna is characterised by influx of many palaeoequatorial Tethyan taxa by comparison with the underlying Artinskian fauna. The palaeobiogeography of fusuline fauna in the Qiangtang Block from the Artinskian to the middle Kungurian is characterised by a pronounced transition from peri-Gondwanan affinity to a transitional affinity (Tethyan Cimmerian subregion). This transition is considered to have resulted from the combined effects among a northward drift of the Qiangtang Block, contemporaneous global climatic amelioration during the Permian, and the oceanic currents along the new-formed Neotethys Ocean.