详细研究了首次发现于甘肃花海盆地截大板沟下白垩统下沟组的介形类化石。根据它们的组合面貌及其在国内外分布的主要层位，认为原划归为上侏罗统，并含有丰富介形类和轮藻化石的这套地层应属下白垩统下统下沟组，其时代为早白垩世Ｂｒｒｅｍｉａｎ期。

The ostracods, collected for the first time from the Early Cretaceous Xiagou Formation at Jiedabangou, Huahai Basin, Gansu Province, have been systematically studied and described in this paper. There are 4 genera and 8 species. The Mesozoic sequence along the southern margin of the Huahai Basin also has been reconstructed according to the fossil association feature, lithologic and sedimentary characteristics, as well as structures of the section. From the fossil feature and the main strata from which the ostracods are collected, it can be deduced that the strata containing abundant ostracods and charophytes, which have been referred to Middle Late Jurassic, are the Xiagou Formation developed in Barremian of Early Cretaceous.

Q913.2 Q913.653