Palaeoworld 16 (2007) 222–232 Research paper Ostracods from the Lopingian and Permian–Triassic boundary beds at the Gyanyima section in southwestern Tibet, China Sylvie Crasquin-Soleau a,∗ , Shu-Zhong Shen b , Wen-Zhong Li b , Chang-Qun Cao b a CNRS, UMR 5143 “Pal´ eobiodiversit´ e et Pal´ eoenvironnements”, Laboratoire de Micropal´ eontologie, Universit´ e Pierre et Marie Curie, T. 46-56, E.5, Case 104, 75252 Paris Cedex 05, France b State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, PR China Received 9 October 2006; received in revised form 26 January 2007; accepted 8 May 2007 Available online 18 May 2007 Abstract Ostracods are reported for the first time in the Late Permian Lopingian to earliest Triassic carbonate sequence in the Ngari region, southwestern Tibet, China. Fifty-three species are recognized, of which 19 are illustrated. One new species (Carinaknightina tibetensis n. sp.) is described and one species is renamed (Bairdia wangi n. nom.). The ostracod fauna as a whole is very similar to those in the Palaeo-Tethys and characteristic of warm water platform deposits. The Early Triassic ostracod assemblages in the section show no substantial difference from the Lopingian assemblages. The palaeoenvironments of the Late Permian and earliest Triassic appear to be open marine with normal salinity and oxygen concentration; there are no indications of anoxic conditions in the Early Triassic in the studied area. © 2007 Nanjing Institute of Geology and Palaeontology, CAS. Published by Elsevier Ltd. All rights reserved. Keywords: Ostracods; Permian–Triassic sequence; Gyanyima section; Tibet 1. Geological setting The ostracods recorded in this paper come from the Gyanyima section, which is located in Burang County in the Ngari region of southwestern Tibet. It is about 30 km north of the China-India border and about 50 km northwest of the Burang County Town (Fig. 1) in Tibet. The Indus-Tsangbo Suture Zone passes about 30–50 km north of the section. Palaeogeographically, the section represents some isolated carbonate build- ups or seamounts deposited in Neo-Tethys between the Himalayan Tethys Zone and the Lhasa Block during the ∗ Corresponding author. E-mail address: crasquin@ccr.jussieu.fr (S. Crasquin-Soleau). initial rifting stage of the Neo-Tethys (Guo et al., 1991; Shen et al., 2003, 2006). The Permian deposits in the Gyanyima section belong to the “Tibetan Facies” (Diener, 1897) that is charac- terized by reddish limestone and contain mixed faunas with both Cathaysian and Gondwanan affinities. Accord- ing to Wang and Xu (1988) and Guo et al. (1991), the Guadalupian-Lopingian strata have been divided into two formations, the Xilanta Formation below and the Gyanyima Formation above. The Xilanta Formation is more than 1373 m thick and consists of two members (Wang and Xu, 1988). The lower member is composed of reddish bioclastic limestone, limestone breccia interbedded with basalt and contains the fusulinids Neoschwagerina douvillei, Pseu- dodoliolina ozawai, Chusenella douvillei, Verbeekina 1871-174X/$ – see front matter © 2007 Nanjing Institute of Geology and Palaeontology, CAS. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.palwor.2007.05.001