开鲁盆地东北部钱家店凹陷晚白垩世姚家组孢粉组合及其古气候意义

对于开鲁盆地姚家组孢粉学的研究不仅丰富了该地区晚白垩世孢粉学资料，而且为该地区晚白垩世地层划分与对比提供了依据.通过对开鲁盆地钱家店凹陷钻孔QIV-48-61深315~447 m井段的岩心做了详细采样、描述，并进行了孢粉化石的处理、鉴定和分析，在其中的10个层位中发现了丰富的孢粉化石，共计73属88种，并建立了3个孢粉组合，自下而上依次为Schizaeoisporites-Cyathidites-Tricolpopollenites，Schizaeoisporites-Classopollis-Taxodiaceaepollenites和Schizaeoisporites-Exesipollenties-Tricolpopollenites，根据孢粉组合内一些重要分子的地质时限及与外区有关孢粉组合的对比，将其时代划归为晚白垩世Coniacian晚期-Santonian早期，其层位相当于姚家组.根据孢粉母体植物形态和生态特征、干湿度环境和气候环境，将其孢粉植物群反映的植被、干湿度和气候带划分为3个演化阶段:第1演化阶段(405.9~413.2 m)沉积时期植被面貌大体为针叶林与草本共生，对应于湿润、半湿润的热带-亚热带气候；第2演化阶段(389.7~405.9 m)植被面貌演化为以高大乔木型针叶树种占优势地位，并出现一次明显的干旱化事件，对应于半干旱的热带-亚热带气候；第3演化阶段(336.0~389.7 m)植被面貌与第1阶段相似，为针叶林与草本共生，干旱化有所缓解，对应于半湿润-半干旱的热带-亚热带气候. 

Late Cretaceous Palynological Assemblage and Its Palaeoclimate Record from Yaojia Formation in Qianjiadian Depression,Kailu Basin

The study on the palynology from the Yaojia Formation can provide palynology data and lay the basis on Late Cretaceous stratigraphic classification and correlation in the northeastern area of Kailu basin. Abundant sporopollen fossils of 88 species from 73 genera were recognized from the interval of 315 to 447 m of well QIV-48-61 in the Qianjiadian depression, Kailu basin in this study. Three sporopollen assemblages are established, namely the Schizaeoisporites-Cyathidites-Tricolpopollenites assemblage, the Schizaeoisporites-Classopollis-Taxodiaceaepollenites assemblage and the Schizaeoisporites-Exesipollenties-Tricolpopollenites assemblage. According to the geological range of some important elements and the correlation with relevant assemblages of other areas, the geological era of these sporopollen assemblages is assigned to the Late Cretaceous, which is equal to the Late Coniacian-Early Santonian Stage. Based on ecological characteristics, climate and humidity condition for the vegetation type of the sporopollen from the Qianjiadian area, 3 phases of paleovegetation and paleoclimate are reconstructed as follows. (1) It was humid/semi-humid tropic-subtropic climate during the interval of 405.9 to 413.2 m, presenting a vegetation landscape of coniferous forest and grass. (2) The vegetation type during the interval of 389.7 to 405.9 m was characterized by the dominance of coniferous forest, and the climate turned hot and dry, marked by the increase in the drought-tolerant taxa, corresponding to semi-arid tropic-subtropic climate. (3) Similar to the first phase, the vegetation type during the interval of 336.0 to 389.7 m was also coniferous forest including grass, which belonged to semi-humid and semi-arid tropic-subtropic climate.