北山地区中口子盆地下白垩统赤金堡组孢粉组合及其意义  

Palynological Assemblage and Its Significance of the Lower Cretaceous Chijinbao Formation in the Zhongkouzi Basin,Beishan Area

作　　者：任文秀[1,2] 胡斌 唐德亮[2] 吴靖宇 孙柏年 Ren Wenxiu;Hu Bin;Tang Deliang;Wu Jingyu;Sun Bainian(Geological Survey of Gansu Province,Lanzhou 730000,China;School of Earth Sciences,Lanzhou University,Lanzhou 730000,China;Changji Vocational and Technical College,Changji 831100,China)

机构地区：[1]甘肃省地质调查院,甘肃兰州730000 [2]兰州大学地质科学与矿产资源学院,甘肃兰州730000 [3]昌吉职业技术学院,新疆昌吉831100

出　　处：《地球科学》2025年第3期1234-1249,共16页Earth Science

基　　金：甘肃省自然科学基金项目(No.20JR5RA039);国家自然科学基金项目(Nos.42362003,32170222,31870200).

摘　　要：孢粉化石在确定地层时代和恢复古气候方面都具有重要指示意义.本文首次对北山地区中口子盆地下白垩统赤金堡组中段的孢粉化石进行了细致的分析,共获得孢粉56属84种,其中蕨类植物孢子含量为29.3%,裸子植物花粉含量为62.6%,被子植物花粉含量为8.1%.依据具有时代意义孢粉分子,将赤金堡组中段的地质时代厘定为早白垩世中期Hauterivian-Aptian.并划分出3个孢粉组合,底部为Ephedripites-Pterisisporites-Retitricolpites组合,中部为Classopollis-Cicatricosisporites-Tricolpites组合,上部为Triporoletes-Laricoidites组合.3个孢粉组合带从老到新分别代表南亚热带半干半湿的针叶林、灌草丛到亚热带半干旱的针叶林、灌木丛再到北亚热带半湿润针叶林植被类型,气候呈现先变干热后变湿热的特征.Fossil spores and pollen are important indicators for stratigraphic age determination and paleoclimate recovery.In this paper,we first reported the palynological assemblage in the middle part of the Lower Cretaceous Chijinbao Formation in the Zhongkouzi basin of the Beishan area.A total of 56 genera and 84 species of spores and pollens were obtained from the deposits,including 29.3%of fern spores,62.6%of gymnosperm pollens,and 8.1%of angiosperm pollens.Based on the significant spore and pollen components in the palynological assemblage,we assigned the middle part of the Chijinbao Formation to the middle Early Cretaceous Hauterivian-Aptian.We divided three sequences based on palynological assemblage characteristics,with Ephedripites-Pterisisporites-Retitricolpites assemblage at the bottom,Classopollis-Cicatricosisporites-Tricolpites assemblage at the middle,and Triporoletes-Laricoidites assemblage at the top.Three Palynological assemblages from old to new respectively represent the vegetation of southern subtropical semi-dry and semi-humid coniferous forests,scrubs to subtropical semi-arid coniferous forests,northern subtropical semi-humid coniferous forests.The climate shows a characteristic of first becoming dry and hot and then becoming hot and humid.

关 键 词：北山地区 中口子盆地 赤金堡组中段 孢粉组合 地质时代 古气候 地层学 

分 类 号：P52[天文地球—古生物学与地层学]