【摘要】 本文研究的介形类化石主要采自鄂尔多斯盆地的西南缘,即陕、甘、宁交界地区的志丹群,计23种隶属于9属和4亚属,其中有9新种。 根据介形类在剖面上的分布状况与特征,可将志丹群的介形类划分为二个组合。自下而上为: 1.Cypridea—Damonella-Latonia组合,其时代为早白垩世中期,相当于欧洲的凡兰今至巴列姆期; 2.Cypridea-Ziziphocypris-Candona组合,其时代为早白垩世晚期,并相当于欧洲的阿普第至阿尔必期。 上述两个介形类化石组合的特征虽然包含有我国华北区的少数分子,但总的面貌却非常接近于华南区相对应的介形类化石组合。因此,笔者认为鄂尔多斯盆地西南缘,可能位于华南区的北缘,但也不排除有属过渡区的可能性。更多还原

【Abstract】 The ostracods studied in this paper were mainly collected from the Zhidan Group of the southwestern Ordos Basin, the border area of Ningxia, Gansu and Shaanxi, which comprise 23 species in 9 genera and 4 subgenera, with 9 new species and 1 genus Latonia described and illustrated in detail.The ostracods of the Zhidan Group can be separated into two ostracod assemblages in ascending order as follows:1. Cypridea-Damonella-Latonia Assemblage of Valanginian to Barremian age;2. Cypridea-Ziziphocypris-Candona Assemblage of Aptian to Albian age.Both ostracod assemblages are very similar in characters to the corresponding ostracod assemblage of the South China Region. Only a few members of the assemblages are characteristic of the North China Region, suggesting that the southwestern Ordos Basin might have been near to the northern border of the South China Region.更多还原