柴达木盆地奥陶纪生物古地理归属研究

PALAEOBIOGEOGRAPHY AFFILIATION OF ORDOVICIAN FAUNAS OF THE QAIDAM BASIN

将柴达木盆地奥陶纪的笔石、三叶虫和腕足类及其代表属与中国其他地区——塔里木盆地、准噶尔盆地、陕甘宁地区、华北地区和华南地区进行对比,先统计出每个地区生物属的数目,再分别统计出两个地区对应生物的共有属的数目,根据公式O_tc=C/(N_1N_2)^(1/2)计算出大冢相似系数,在此基础上进行Q型聚类分析,即列出相似系数矩阵,采用相似系数的加权平均法,进行多次聚类.利用每次聚类结果划分生物古地理单元,从而解决柴达木盆地奥陶纪生物古地理归属问题.结果表明:早奥陶世可划分为西北生物区和东南生物区,西北生物区又可分出塔里木-柴达木生物亚区和准噶尔生物亚区,东南生物区则可分为华北生物亚区和陕甘宁-华南生物亚区,柴达木盆地属于塔里木-柴达木生物亚区;中奥陶世可分为西北生物区、柴达木生物区、华北生物区和陕甘宁-华南生物区.

The trilobites, graptolites and brachiopods of the Ordovician in the Qaidam Basin are compared with those in other areas of China, such as the Tarim Basin, the Shanxi - Gansu - Ningxia (Shanganning) area , North China and South China. On the basis of the calculation of the Otsuka similarity coefficient, the Q- cluster analysis is made. The palaeobiogeographical provinces and subprovinces are divided. The study shows that, in the Early Ordovician, China can be divided into the Northwest province and the Southeast province. Moreover, the Northwest province can be divided into the Tarim- Qaidam subprovince and the Jungar subprovince, and the Southeast province can be divided into the North China sub-province and the Shanganning - South China subprovince. The Qaidam Basin belongs to the Tarim - Qaidam subprovince. In the Middle Ordovician, China can be divided into the Northwest province, the Qaidam province, the North China province and the Shanganning - South China province.