中文摘要：

鄂尔多斯盆地西南部西峰油田中上三叠统延长组长8段和长7段钻井岩心中发现丰富的孢粉化石，分别命名为Aratisporites-Punctatisporites组合和Asseretospora-Walchiites组合，组合特征分别与盆地东南部发现的铜川组孢粉组合和延长组孢粉组合相似，地质时代分别为中三叠世晚期Ladinian期与晚三叠世早期Carnian期。通过孢粉植物群类型地层分布特征及其生态环境讨论，推测盆地区中晚三叠世气候温暖潮湿，雨量充沛，植被茂盛。孢粉植物群所反映的古气候为温带一亚热带暖湿或湿热气候。这是由于本地区当时处于较低的纬度，且濒临大型湖泊，而长8一长7段沉积时期正处于湖泊扩张的鼎盛期。

英文摘要：

Abundant sporo-pollen fossils were found in cores from the Chang 8 and Chang 7 members of the Yanchang Formation in the southwestern Ordos basin, NW China. The assemblage of Chang 8 member was denominated by Aratisporiteas-Punctatisporites, and the assemblage of Chang 7 member as Asseretospora-Walchiites. Their charae teristies are similar to those of the assemblages of the Tongchuan Formation and the Yanebang Formation in the southeast Ordos basin, respectively. Their geological ages are Ladinian of late Middle Triassic and Carnian of early Late Triassic respectively. The sporo-pollen and their ecological distributions in these members suggest the paleocli mate of the eastern Gansu Province in the Middle and Late Triassic was warm and wet, under a temperate to subtropi cal zone. The wetter paleoenvironment during the Chang 8 and Chang 7 sections deposited in eastern Gansu Province large-scale lake transgression was happening, with the largest lake