中文摘要：

西藏日喀则沿雅鲁藏布江分布的大竹卡组为一套杂色的砂砾岩沉积，与新生代印度一劳亚板块的碰撞和青藏高原的隆升具有密切的联系。迄今为止，其中尚未有可靠的化石发现用于指示时代。当前研究根据从大竹卡组中的一些粉、细砂岩中获得的较丰富的孢粉化石，首次探讨其沉积时期的古植物区系和陆地生态环境特征。孢粉组合以榆科和胡桃科具孔类和壳斗科三（拟孔）沟类被子植物花粉占优势，也见有较多的蕨类植物孢子和裸子植物两气囊花粉，其时代可能是渐新世-旱中新世。孢粉组合反映大竹卡组沉积期间恰布林一带的气候比较温暖、湿润，揭示印度、劳亚大陆碰撞早期的热带-南亚热带低山丘陵环境。植物区系横向对比表明，恰布林自始新世末以来向北位移了大约500km。

英文摘要：

The variegated sandstone and conglomerate beds of the Dagzhuka Formation are exposed widely along the Yarlung Zangbo River in the Xigaze region, Xizang （Tibet）, associated with the collision of the Indian and Laurasian plates and the uplift of the Qinghai-Xizang Plateau. So far few fossils have been discovered to allow a reliable dating of the strata. In this study, we gathered a variety of fossil spores and pollen from the fine beds of this formation. These fossil findings not only provide us for the first time with a substantial dating of Oligocene to Early Miocene for this formation but also are helpful in determining the palaeofloras and continental palaeo-ecosystem in the eastern Xigaze region during that time. The palynological associations are dominated by porate pollen assigned to the families Ulmaceae and Juglandaceae and tri-colp （oroid）ate pollen assigned to the Fagaceae. Gymnospermous pollen, mainly bisaccates, and pteridophytic spores are also fairly diverse. The occurrence of Magnastriatites, Caryapollenites cf. simplez, Echitricolporites minor, Engelhard- tioidites, Florschuetzia cf. trilobata, F. sp. and Graminidites strongly indicates an Oligocene to Early Miocene age for the Dagzhuka Formation. Considering that some of these taxa occurring earlier in tropical areas and that Pentapollenites is mainly encountered in pre-Oligocene strata despite its top horizon being documented as late Oligocene in China and Upper Oligocene aboard, the age of the palynofloras may extend to the late Eocene. The palaeovegetations are assumed to be either evergreen or deciduous and in line with warm and humid climate. The palynofloral associations also suggest a low mountainous landscape for the study area and an approximate palaeo-latitude of N 25°. This implies that the Qiabulin area moved about 500 km northward since the latest Eocene（or Oli- gocene）.