Abstract: Synthetic analysis of 170 trilobite genera, 210 brachiopod genera, and 87 cephalopod genera leads to the recognition of two regions separated by the Irtys (river)-Sino-Mongolian boundary-Xar Molon (river)-Changchun line: the Middle Asia-East Asia region of the Proto-Pacific realmand the Northern Asia region of the Proto-Atlantic realm.The former is characterized by the trilobites Tangyaiinae and Hammatocnemiidae, and is closely related with the Australian and the Southern European regions in many aspects. For example, Cekovia and Pseudopetigurus are present both in the Middle Asia-East Asia region and in the Southern European region; Neseuretinus is present in all the above three regions; Pliomerina is widely distributed in the Middle Asia-East Asia region, in addition, it is also found in southeastern Australia. The Middle Asia-East Asia region is further subdivided into the North China, the Tarim, and the Kazakhstan provinces. The Kazakhstan province possesses many taxa that are also present in North America, South China, Tarim, and the Ordos area of North China, suggesting a transitional position between the two realms.The Ordos area of the North China province and the Tarim province are very similar statistically, probably due to similar environmental setting. Trilobite endemic ratios are usually low in various provinces (10%-15%), especially in marginal sea or deeper water facies.Cephalopods have a higher endemic ratio in the North China(30%) and Siberia (20%) provinces. Brachiopods are the most widely distributed and numerous in the study area, but their provincialism is quite indistinct.

Key words: North China, Mongolia, Kazakhstan, Siberia, Ordovician, Paleobiogeography

摘要： 根据对170属三叶虫、210属腕足类及87属头足类的综合分析结果，本研究区可分为中亚-东亚区和北亚区(二者分别属于古太平洋大区和古大西洋大区)。中亚-东亚区包括哈萨克斯坦、塔里木及华北3个分区，其中哈萨克斯坦分区包括哈萨克斯坦、中亚南天山及新疆准噶尔，以三叶虫 Opsimasaphus 和 Heptabronteus 以及腕足类 Ishimia, Shlyginia和 Eoanastrophia 为代表；塔里木分区以三叶虫 Taklamakania 属为代表，另有丰富的 Lituitidae 和 Oncoceratidae 科头足类；华北分区包括华北地台区，鄂尔多斯及祁连等地区，以头足类比较丰富及其地方性为特色。北亚区分为西伯利亚、阿尔泰-萨彦和兴蒙3个分区，其中西伯利亚分区以三叶虫 Monorakos、腕足类 Evenkina, Evenkinorthis和 Lenatoechia 以及头足类 Intejacerida 目为代表；阿尔泰-萨彦分区以三叶虫 Malinaspis 和腕足类 Ujukites 为代表；兴蒙分区包括我国东北及蒙古东部，除局部性的地方分子外，特征分子不明显。值得指出的是，哈萨克斯坦分区含有许多广泛分布于北美、华南、塔里木和华北鄂尔多斯地区的种属，意味着它当时处于两大区的过渡地位。

关键词: 中国北部, 蒙古, 哈萨克斯坦, 西伯利亚, 奥陶纪, 古生物地理