Palaeontology of the 1985 Tibet geotraverse, Lhasa to Golmud

Abstract
Palaeontological collections made on the 1985 Geotraverse are used to date the associated strata and provide information about palaeoenvironments. A biostratigraphical and palaeoenvironmental framework for the Tibetan plateau is constructed. The crucial stratigraphical and palaeontological evidence for dating volcanic sequences, flysch basins, open oceanic sediments, latest marine sediments and terrestrial red beds in each terrane is reviewed. A quantitative palaeobiogeographical analysis from the Carboniferous to early Triassic is presented for the Tibetan fauna and flora, to establish the biotic relationships between the various terranes. This is based largely on coral, brachiopod and fusulinid distributional data, but other groups have also been analysed, including the Permian terrestrial flora. This analysis demonstrates a clear diversity gradient from equatorial or sub-equatorial biotas in the north to temperate biotas in the south during the late Palaeozoic. No suture line consistently m arks the position of a faunal/floral break during the late Palaeozoic and there appears to have been no physical barrier (such as a large ocean) to biotic dispersal between Tibetan terranes at this time. Climate is seen as the most likely factor dominating biotic distribution in this region and the early Permian glaciation had a profound effect on marine faunal distributions in Tibet.

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