内蒙古开鲁盆地早白垩世阜新组孢粉组合

A SPOROPOLLEN ASSEMBLAGE FROM THE EARLY CRETACEOUS FUXIN FORMATION IN THE KAILU BASIN, NEI MONGOL

开鲁盆地陆家堡坳陷白垩系十分发育,富含各门类生物化石。根据坳陷内钻井所采样品,系统研究了早白垩世阜新组孢粉化石,建立以Cicatricosisporites Laevigatosporites Tricolpopollenites 为代表的孢粉组合。根据典型分子时代分布及横向组合对比,确定其地质时代为巴列姆—阿普第期,孢粉植物群反映的气候特征为潮湿的亚热带。

The Kailu Basin lies in the southeast part of Nei Mongol(Inner Mongolia). The Lujiapu Depression is one of its basic structure units. Results of oil drilling project show that the Cretaceous sediments are widespread in the subsurface of the depression.Abundant sporo-pollen taxa have been found from the Early Cretaceous Fuxin Formation.They are grouped into the Cicatricosisporites-Pilosisporites-Tricolpopollenites assemblage.It is characterized by: 1.Gymnospermous pollen amount to about 68.3%,most of them are Disaccate pollen, such as Pinuspollenites, Piceaepollenites, Cedripites, Podocarpidites, Protoconiferus, Pseudopicea, etc. Taxodiaceaepollenites,Cerebropollenites,Perinopollenites,Psophosphera and Inaperturopollenites are next in contents. A certain amount of pollen grains of Cycadopites,Jiaohepollis,Monosulcites and Classopollis are also found in the assemblage. 2.Pteridophytic spores amount to about 29.7%.Spores related to Lygodiaceae are dominant which are composed mainly of Cicatricosisporites(7.8),Pilosispo-rites(1.2), Appendicisporites,Lygodiumsporites,Klukisporites,Impardecispora and Maculatisporites. Laevigatosporites(1.9) are also an important elements of the assemblage. Cyathidites, Deltoidospora and Osmundacidites occur frequently. In addition,there are some other elements in lower content,such as Crybelosporites,Densoisporites,Hsuisporites,Foraminisporites,Aequitriradites,Triporoletes,Schizaeoisporites, etc. 3.An distinct feature of this assemblage is the appearance of some angiospermous pollen, including Tricolpopollenites,Retitricolpites,Clavatipollenites and Asteropollis. 4.According to the characteristics mentioned above, this assemblage should be regarded as Barremian-Aptian stage of the Early Cretaceous age. 5.Most of the palynomorphs in this assemblage are the common members of the North China Microflora, representing a humid subtropical paleoclimate.