浙江长兴煤山D剖面早三叠世孢粉组合及全球对比意义

在长兴煤山D剖面下三叠统殷坑组14 m厚的地层内(第25-60层)密集采孢粉样89件, 从12块样品中获得孢粉化石47属50种, 据此将该剖面下三叠统底部的孢粉组合定为Lundbladispora-Taeniaesporites-Equisetosporites组合.组合中裸子植物花粉占优势, 为59.0%~79.6%;蕨类植物孢子次之, 为20.4%~41.0%;裸子植物花粉中以无肋双气囊类花粉为主, 含量为19.7%~54.4%, 多沟类花粉虽仅见Equisetosporites一属, 但含量高, 最高达24.3%.蕨类植物孢子中光面三缝孢类含量最高, 为14.3%~24.4%, 以圆形的Puncatisporites为主, 最高可达16.2%.孢粉组合Lundbladispora-Taeniaesporites-Equisetosporites与同一剖面的早三叠世牙形石第2带Isarcicella isarcica带及第3带Clarkina carinata-C.planata带相重合.这对当前正在进行的陆相二叠系-三叠系界线的准确划分提供了重要的参照系.研究还表明, 煤山D剖面早三叠世早期的孢粉组合与中国北方区的早三叠世同期的孢粉组合对比较为困难, 而与华南各地的对比较为吻合, 说明中国南、北方古生代孢粉组合向中生代孢粉组合转变的时间并不一致, 北方较早, 南方较晚. 

Palynological Assemblage in Section D of Meishan, Changxing, Zhejiang and Its Significance of Global Correlation

Altogether 47 genera and 50 species were identified in 12 of all the 89 samples taken within 14 m Yinkeng Formation (Bed 25-60) in Meishan Section D (GSSP) of Changxing in Zhejiang. The palynological assemblage is Lundbladispora-Taeniaesporites-Equisetosporites with the dominance (59.0%-79.6%) of gymnosperm pollen and secondary (20.4%-40.0%) of fern spore. The gymnosperm pollen was dominated by the instriate bisaccate (19.7%-54.4%) characterized by the greatest diversity and abundance of coniferousbisaccate pollen. The striate bisaccate pollen is secondary and the polyclicate pollen composed of only one genus Equisetosporites has an abundance up to 24.3%. The fern spore was dominantly represented by Liotriletes (14.3%-24.4%) with the predominance of the cycloid Puncatisporites (16.2%). The secondary are the echinate, granular and verrucose trilete spores (1.9%-21.2%). The fastigiate trilete spore has a relatively low quantity but spreads wide, mainly Lundbladispora. Zonotrilete spore is quite rare. Significantly, this palynological assemblage in Section D of Meishan, correlative with the conodont Isarcicella isarcica Zone and the Clarkina carinata-C. planate Zone, is comparable with palynological assemblages observed in other sections in South China but incompatible with those in North China. This discrimination suggests the earlier evolution of Mesozoic palynological assemblage in North China than in South China.