塔里木盆地奥陶系苔虫多样性演变

本文研究了塔里木盆地奥陶系苔虫的分布延限和演化规律。苔虫的演化分为四个阶段:第一阶段为鹰山组—一间房组中下部沉积期,苔虫多样性和丰度均很低;第二阶段为一间房组上部—吐木休克组沉积期,苔虫的多样性处在一种波动上升的状态;第三阶段包括良里塔格组良五段—良四段沉积期,苔虫多样性和丰度均有一定程度的增加,而且绝大部分属种在接下来的第四阶段都有出现;第四阶段在良里塔格组良三段—良一段沉积期,是苔虫总体多样性明显增长的时期,也是本区奥陶纪苔虫的重要辐射期。随后,展开苔虫的多样性分析的研究。研究发现塔里木盆地奥陶系苔虫的演化趋势与世界范围的演化趋势基本一致,说明是受苔虫宏演化规律控制的。

DIVERSITY EVOLUTION OF ORDOVICIAN BRYOZOAN IN THE TARIM BASIN OF XINJIANG,NW CHINA

This paper deals with the diversity evolution of bryozoans during the Ordovician in the Tarim Basin of Xinjiang,China.The evolution can be divided into four stages.During the first stage,the deposition period of the Yingshan and lower Yijianfang formations,the bryozoans in the Tarim Basin had low diversity and abundance.During the second stage,the deposition period of the upper Yijianfang and Tumuxiuke formations,the abundance and diversity of bryozoans in the Tarim Basin were unevenly increasing.During the third stage,the deposition period of the Member5 to 4of the Lianglitag Formation,the diversity and abundance of bryozoans in the Tarim Basin had a moderate increase,and most genera and species of this stage lasted to the next stage.During the fourth stage,the deposition period of the Member 3through 1of the Lianglitag Formation,the diversity and abundance of bryozoans in the Tarim Basin greatly increased,constituting the radiation period of Ordovician bryozoans in the Tarim Basin.Based on the comparison with previous study,the bryozoans in the Tarim Basin show a similar evolution history to that of other regions.