【作者】 闫晶晶；

【导师】 万晓樵；

【作者基本信息】 中国地质大学（北京） ， 古生物学与地层学， 2007， 硕士

【摘要】 松辽盆地是中国东北一大型中新生代沉积盆地，盆地内含有丰富的化石，如孢粉、介形类、叶肢介等。本次研究通过对青山口地区两条发育良好的剖面，即李家坨子剖面和后金沟剖面，进行系统的采样、鉴定和统计，分析其孢粉、介形类化石组合特征及含量变化情况，并结合叶肢介化石和岩性等资料，厘定地层的层位，进而恢复当时的古生态、古气候。主要取得如下研究成果：对松辽盆地青山口地区李家坨子剖面重新进行了测量及描述，识别了孢粉Balmeisporites-Cyathidites-Classopollis组合，介型类Cypridea dekhoinensis-Limnocypridea copiosa组合，叶肢介Nemestheria qingshankouensis-Cratostracusmerus merus组合。通过地层对比，认为李家坨子剖面属于青山口组二段下部，不同于前人的青山口一段的结沦。根据对孢粉的分析，认为该沉积期总体属于温暖、湿润的热带、南亚热带气候。在青山口组二段沉积初期，根据介形类化石的保存特征及丰度、分异度，并结合其他资料，得出当时的湖水总体处于浅湖一半深湖环境。湖水稳定、清澈富氧，并且富含Ca²⁺，并在开始阶段经历了一次迅速的湖水加深的过程，反映一种湿热的气候环境。在后金沟剖面，识别了孢粉Proteacidites-Cyathidites-Dictyotriteles和Lythraites-Aquilapollenites-Schizaeoisporites组合，介形类Cypridea gunsulinensis-Cypridea ardua和Ilyocyprimorpha netchaevae-Periacanthellaportentosa-Cyprideaordinata组合，叶肢介Estheritils mituishi组合。根据岩性特征，认为后金沟剖面属于嫩江组一段上部一二段下部，从而在青山口地区首次发现了嫩江组地层。根据对孢粉的分析，认为该沉积期总体属于湿润到半湿润的热带、亚热带气候，其中在嫩江组二段底部黑色页岩的沉积期显得气候更加湿热，向上开始逐渐变干凉。根据介形类化石，推测在嫩江组一段—二段沉积过渡期发生了一次大规模的湖侵。伴随着湖侵，介形类经历了一个衰退、消亡、复苏的过程。更多还原

【Abstract】 The Songliao Basin is a large Mesozoic and Cenozoic sedimentary basin yielding abundant fossils, such as: sporopollen, ostracods, Esthenaus. Sporopollen, ostracods samples were collected and identified from the Lijiatuozi and Houjingou sections in the Qingshankou area. By lithology and biotic characters, the section has been correlated, the paleoeclogy and paleoclimate have been analyzed. The following results have been achieved:The Balmeisporites- Cyathidites-Classopollis sporopollen assemblage, Cypridea dekhoinensis- Limnocypridea copiosa ostracod assemblage, and Nemestheria qingshankouensis -Cratostracusmerus merus Esthenaus assemblage have been recognized from the Lijiatuozi section. Lithologically, the section has been correlated as lower Member 2 of the Qingshankou Formation, which differrs from the previous research refferring it to the Member 1 of Qingshankou Formation. Based on the ostracod paleoeclogical features such as morphology, abundance, diversity, prevervation, and on the features of sporopollen such as climate distribution, humidity type, combined with characteris of sedmentation, key minerals and fossil Esthenaus, the paleoeclogy, paleoenvironment and paleoclimate have been constructed. According to the analysis and statistics of sporopollen, the assemblage implies mild, humectation, tropical to south subtropical climate. In the early sedmentary period of the Member 2 of Qingshankou Formation, the paleoenvironment is suggested as shallow-sub deep lake, which was stable, rich in oxgen and Ca²⁺, indicating a pattern of humid and hot climate.Sporopollen, ostracods samples were collected from the Houjingou section in the Qingshankou area, Songliao basin. The author has recognized two sporopollen assemblages: Proteacidites-Cyathidites-Dictyotriteles and Lythraites-Aquilapollenites-Schizaeoisporites, two ostracod assemblages: Cypridea gunsulinensis-Cypridea ardua and Ilyocyprimorpha netchaevae- Periacanthella portentosa-Cypridea ordinate, one Esthenaus assemblages: Estheritilis mituishi; Bylithology and biotic characters, the section has been correlated to the sequence from upper part of Member 1 to lower part of Member 2 of the Nenjiang Formation. According to the analysis and statistics of sporopollen, the climate change from tropical, subtropical, humectation to subhumid climates has been proposed. In this period, a more humid and hot climate was represented by the black and oil shale deposits at the lowermost Member 2 of the Nenjiang Formation. Then, the climate tended to be dry and cool. Along with the lake trasgression in the sedmentary period of top Member 1 to Bottom Member 2 of the Nenjiang Formation, the ostracods underwent a progress of species decline, disappearance and recovery.更多还原