THE ANALYSIS METHODOLOGY OF POLLEN FROM THE MESOZOIC—CENOZOIC RED BEDS IN NORTHERN TIBET

A group of red interbedded sandstone, siltstone and clay\|stone occur in the inland of northern Tibet. During the last 50 years, a lot of researches have been done at this group of beds along the Qinghai\|Xizang highway in the Kekexili area.. According to the lithological characters, the strata have been divided into tow parts, the lower part named as the Feng huoshan group, and the upper part the Yaxicuo group. It is obscure to the age of the strata. For example, Yi jixiang et al. (1990) put them in early Pliocene in the light of the microfossils which they found at the foot of Feng huoshan mountain. The fossils include (1) Charophyta: Rhabdochara? sp ., Peckichara subsphecrica?, Cyrogoniae; (2) Ostracoda: Cypris sp .; (3) Gastropod: Sinoplanorbis sp ., Amnicola sp ., Bithynia sp .; and (4) Sporopollen: Tricoporopollenites nactonodus ?, Polypodiceoisporites, Cyathidites, Schizosporis, Pediastrum. Based on different species of Charophyta, Ostracoda, Gastropod, Bivalve, Sporopollen, Zhang Yifu et al. (1994) refer the strata to Cretaceous. The lower abundance of the fossils from previous research gave lower precision of fossil identification. Thus, the age of the strata was confusion.