西藏吉隆盆地新近纪孢粉组合及古地理研究

西藏吉隆盆地沃马组发现的孢粉组合佐证了青藏高原在上新世晚期持续稳定的隆升。该盆地强波沟剖面共划分了6个孢粉组合带,古植被是以松和冷杉为建群种的亚热带山地针阔叶林植被,反映了温暖湿润的古气候环境,期间经历几次明显的气候冷暖波动;沃马组岩相古地理分析表明:沃马组沉积环境主要是河流和湖泊沉积环境,局部地区为冲积扇及沼泽环境。其古地理环境演化经历了早期形成阶段、半开放式湖盆阶段及封闭式湖盆3个演化阶段。

Neogene sporopollen assemblages and paleogeography in the Gyirong basin, Tibet

The sporopollen assemblages discovered in the Woma Formation in the Gyirong basin,Tibet,provide evidence for continuous and stable uplift of the Qinghai-Tibet Plateau during the Pliocene.Six assemblage zones may be distinguished in the Woma Formation in the Gyirong basin.The paleovegetation of the Woma Formation is characterized by subtropical,mountainous,needleleaf and broadleaf forest with Pinus and Abies as the constructive species,reflecting a warm-moist paleoclimatic environment.During the period,there occurred several pronounced climatic cold-warm fluctuations.Analysis of the lithofacies and paleogeography of the Woma Formation indicates that the depositional environment of the Woma Formation was mainly the fluvial and lacustrine one and locally the alluvial fan and swampy one.The evolution of the paleogeographic environment of the Woma Formation progressed through three stages,namely,the early formation stage,semi-open lake basin stage and enclosed lake basin stage.