内蒙古钱家店凹陷晚白垩世姚家组的孢粉组合研究

STUDY ON THE SPOROPOLLEN ASSEMBLAGE FROM THE LATE CRETACEOUS YAOJIA FORMATION IN THE QIANJIADIAN SAG,INNER MONGOLIA,NORTH CHINA

内蒙古钱家店凹陷ML12井等12口井的孢粉材料,是目前所知该凹陷姚家组孢粉类型最丰富、数量最多且保存最完好的,已鉴定出孢粉共计116属,包括蕨类植物孢子51属、裸子植物花粉32属和被子植物花粉33属。根据姚家组中蕨类植物孢子分异度较高及相对含量较低、裸子植物花粉分异度较低及相对含量高、被子植物花粉分异度较低及相对含量波动幅度巨大的孢粉组合特征,将其命名为Exesipollenites-Nevesisporites-Retitricolpites组合。该组合与大庆长垣姚家组孢粉组合具有很好的横向对比性。以塔里木盆地西部东巴组中、下段被子植物花粉的演化阶段为参照标准,钱家店凹陷晚白垩世姚家组的孢粉组合时代应为晚白垩世Coniacian期—Santonian期。本文中的工作填补了钱家店凹陷姚家组孢粉组合研究的空白,并为深入认识我国北方区姚家组沉积时期植物群的特征提供了重要的证据。

12 wells including ML12 contain the most abundant and well-preserved sporopollen in the Yaojia Formation of the Qianjiadian Sag, Inner Mongolia, North China. We identified 116 genera of sporopollen, including 51 genera of fern spore, 32 genera of gymnosperm pollen and 33 genera of angiosperm pollen. According to the sporopollen characters, such as the significantly high diversity and the relatively low content of fern spore, the lower diversity and the relatively high content of gymnosperm pollen, and the lower diversity and comparatively large fluctuations in content of angiosperm pollen, the Exesipollenites- Nevesisporites - Retitricolpites sporopollen assemblage is named, which can be correlated with the sporopollen assemblage from the Yaojia Formation in Changyuan, Daqing, Heilongjiang Province. According to the evolution of the angiosperm pollen in the lower and middle Dongba Formation of the western Tarim Basin, the Exesipollenites- Nevesisporites - Retitricolpites sporopollen assemblage in the Yaojia Formation can be assigned to the Coniacian-Santonian stage of the Late Cretaceous. Our work reports for the first time the sporopollen assemblage from the Late Cretaceous Yaojia Formation in the Qianjiadian Sag, Inner Mongolia and provided an important data for further understanding of the flora characteristics in the sedimentary period of the Yaojia Formation in northern China.