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不同的植物产生不同的孢粉，一定地质时期和特定的自然条件下产生的植物群与特定的孢粉组合对应，因此，孢粉组合可以指示当时的岩相古地理环境。在对伊犁盆地侏罗系孢粉组合特征及古生物图件详细研究的基础上，论证了古生物（孢粉）在层序边界上的特征。通常，层序边界上的古生物在垂向上种类和数量最少，分异度小，界线上、下之间古生物组合大不相同，是一个反映古地理环境有很大变迁的时间界面；而在最大湖泛面附近，古生物种属和数量最多，分异度大，代表了复杂的古地貌及强烈的构造运动期间的古生态组合特征。一个层序可以包含几个不同的生物带；反之，同一生物带也可包含几个层序，这主要取决于生物带所延续的时间长短
Different plants produce different sporopollen, corresponding to the specific sporopollen assemblage in certain geologic period and under specific natural conditions. Therefore, the sporopollen assemblage can indicate the lithofacies paleogeographic environment at that time. Based on a detailed study of the characteristics of Jurassic sporopollen assemblages and palaeontological maps in the Yili basin, the characteristics of paleontology (sporopollen) on the boundaries of sequences are demonstrated. Ordinarily, the paleontology on the boundary of sequence boundaries has the smallest number and diversity in the vertical direction, and the paleontological assemblage is quite different between the upper and lower boundary lines. It is a time interface reflecting the great change of palaeogeographic environment. However, In the vicinity of the flooding surface, the species and number of paleontology are the most abundant and highly differentiated, representing the complex paleogeomorphology and paleoecological assemblage during the intense tectonic movement. A sequence can contain several different biological bands; conversely, the same biological band can contain several sequences, depending on the length of time the biological band lasts