海洋底栖古群落的识别与划分

在分析前人研究成果基础上，提出了识别与划分古群落的5条标准：1）同一古群落应处于相同的沉积环境中，时空分布上相邻的古群落形成于不同的自然地理环境；2）古群落化石群为原地埋藏；3）同一地层剖面中，属于同一古群落的不同层位中所含化石相似率应明显高于不同古群落间的相似率；4）同一古群落的物种组成在不同地点或层位中可以重复出现；5）古群落划分可采用单门类或多门类划分法．结果表明，采用回归分析图解对比法建立区域性复合标准剖面，可以综合不同地层剖面的多种地质信息，最大限度地克服化石标本采集的不完备性和避免人为的主观臆断．通过实例的检验，在古群落识别与划分研究中，Jaccard相异系数是计算和判别古群落相似率高低的有效公式．

Distinguishing and Dividing of Marine Benthonic Palaeocommunities

Based on the predecessors' research results,five criterions to distinguishing and dividing palaeocommunities were proposed: 1) Congener palaeocommunities should be in a same sedimentary environment,and some adjacent palaeocommunities on temporal and spatial distribution should be grown in different physical geography environments;2) The oryctocoenose of palaeocommunity is buried in situ;3) In a same stratigraphic section,the similarity rate of fossil in different horizons of the same palaeocommunities is higher than that of the various palaeocommunities obviously;4) Species composition in the same palaeocommunities appears repeatedly in different locaties and horizons;5) Mono-category and multi-categories methods can be used to divide palaeocommunities.The results indicate that many kinds of geological information of different stratum sections can be colligated to conquer the imperfectness of fossil collection and avoid the subjectivity and forejudgment furthest using the regression analysis schematic correlation to found a territorial multiplex standard section.Jaccard dissimilarity coefficient is an effective formula to calculate and distinguish the similarity rate in distinguishing and dividing palaeocommunities.