A new Brachiopod fauna from the early to middle permian of Southern Qinghai Province, Northwest China

A new brachiopod fauna is described from the Early and Middle Permian of Zadoi and Zhidoi counties, southern Qinghai (Changdu block), northwest China. This fauna includes 13 species in nine genera with Spinomarginifera concentrica n. sp. and Transennatia waterhousei n. sp. The Early to Middle Permian brachiopod fauna from southern Qinghai is very similar to the contemporary Cathaysian faunas of South China with which the new fauna shares 70 per cent of its species. On the other hand, the Qinghai brachiopods also demonstrate a significant link with the Permian brachiopod fauna of the Sino-Mongolian-Japanese Province in northeast China, as suggested by Marginifera septentrionalis and Attenuatella. In particular, the occurrence of the bipolar brachiopod genus Attenuatella suggests that southern Qinghai may have played an important role as a biogeographic stepping stone in the marine faunal interchanges between the northern and southern hemispheres during the Early and Middle Permian.

New progress in the study of Paleozoic strata in the Xainza area, Tibet

The authors discovered and measured a relatively complete Paleozoic section (exposed continuously from the Lower Ordovician to Upper Permian) and collected plentiful fossils of many groups during geological investigations of the 1∶250000 Xainza County Sheet in the period of 2000-2002. It was the first time in Tibet that the representative element Tetragraptus (Paratetragraptus) approximatus of the graptolite zone at the lowermost part of the Early Ordovician Arenigian Stage and the typical elements Waagenophyllum indicum var. crassiseptatum and Liangshanophyllum streploseptatum Graptolithina of the Late Permian Wujiapingian coral fauna. Based on these, the Lower Ordovician Zakang Formation and Upper Permian Mujiu Co Formation were established. It not only improved the Paleozoic stratigraphic sequence in the area but also provided new information for the study of the Paleozoic tectonic movement and evolution of the Qinghai-Tibet Plateau.

Discovery of the Early Ordovician strata in Xianza County, Tibet and its significance

There is no any sediments contain fossils which formed earlier than Middle Ordovician in northern Tibet yet. It is very important whether have developed the Cambrian to Early Ordovician sedimentary strata. During geological mapping of Xainza County in 2000, Tetragraptus approximatus, the typical one of graptolite belts which cosmepolitically distributed in the Arenigian of Early Ordovician, was collected from the so-call Pre-Sinian Nianqingtanggula Group. So there is developped the Early Ordovician sediments and we have established Zakang Formation and Taduo Formation which perfected the Plaeozoic sequences in northern Tibet. According to these, we can realize tectonic control, palaeogeographrc pattern as well as palaeobiogeographic distribution of the Qinghai-Tibet Plateau in the early Paleozoic and also provided the materials to the cosmepolitical biostratigraphic contrast.