【作者】 张栋；

【导师】 张梅生；

【作者基本信息】 吉林大学 ， 古生物学与地层学， 2012， 硕士

【摘要】 论文通过搜集整理前人研究，在野外实地考察和实测剖面基础上，针对兴城地区龙回头盆地海房沟组，以区域内海房沟组的岩石地层对比、对盆地内砂砾岩的粒（砾）度统计分析、所含化石孢粉分析等手段，确定盆地内海房沟组的地层序列，形成的地质时代以及该盆地的沉积环境。论文主要研究内容包括以下几个方面：（1）野外实测3条剖面（即PⅠ兴城龙回头南四道沟海滨中侏罗统海房沟组剖面、PⅡ兴城龙回头滨海公路西侧路堑中侏罗统海房沟组剖面、PⅢ兴城龙回头北海滨中侏罗统海房沟组剖面），通过室内数据整理，岩性组合对比，详细确定龙回头盆地海房沟组岩石地层序列，认为龙回头海房沟组的厚度大于552.4m，是一套主体为黄绿色-褐色中-粗砾、分选较差、次棱角至次圆状的复成分砾岩，并夹有数层紫红色细粒杂砂岩及黄绿色页岩、炭质泥岩的沉积地层。（2）将龙回头盆地内所测海房沟组剖面的岩石地层序列与辽西其它地区（北票盆地、金岭寺-羊山盆地）海房沟组（北票市三宝四坑—上油房沟海房沟组剖面、北票市常河营子乡羊草沟－大水泉子西山中侏罗统海房沟组剖面、锦西县南票区盘道沟中侏罗统海房沟组剖面）进行岩石地层地层对比，其岩石类型、岩性组合基本一致，可以相互对比。并分别从构造位置及盆地演化程度的角度对不同盆地内海房沟组岩性组合的差异作出解释。（3）在龙回头盆地海房沟组中发现陆生植物化石及孢粉化石，根据与辽西地区古生物组合对比，认为龙回头盆地海房沟组中发现的Coniferopsida（松柏纲），Podozamitaceae gen. indet.（苏铁杉科未定属）属于辽西地区Coniopteris-Phoenicopsis植物群的一分子；与鄂尔多斯盆地-东胜地区中侏罗世延安组和辽宁南票地区海房沟组（原郭家店组）孢粉组合相对比，龙回头盆地海房沟组中主要孢粉分子也出现于延安组Cyathidites-Piceaepollenites组合和南票地区海房沟组Cyathidites-Classopollis组合中，得出龙回头盆地海房沟组形成的地质时代为中侏罗世；将龙回头盆地内孢粉组合命名为Osmundacidites–Asseretospora组合。（4）对龙回头盆地中的海房沟组所进行的砾岩粒径统计、砾岩成分统计、砂岩粒度分析研究结果表明：该套地层属于山前坳陷冲积扇相沉积，具有河道沉积和漫流沉积的特征；沉积砾岩的砾石来自周边地区的下伏地质体（地层），没有经过长距离的搬运，属于近源堆积；根据地层中岩性组合的旋回特征，将地层进一步细分为扇根、扇中、扇端亚相。（5）对龙回头盆地中生代的构造背景及构造特征进行讨论，认为龙回头盆地属于山前（间）坳陷盆地。更多还原

【Abstract】 The present thesis is on the research of the stratigraphic sequences、the geological ageand the depositional environments of the Haifanggou Formation in the Longhuitou Basinof Xingcheng City by lithostratigraphic correlation, grain size analysis of sandstone andanalysis of fossil pollen.This study contains the following aspects:(1) Field works on three sections. The section1(PⅠ) is in the Sidaogou ofLonghuitou; the section2(PⅡ) is in the westside of coastal way; the section3(P Ⅲ) is inthe northern beach of Longhuitou. The result of data analyzing and lithologicalassociation correlation indicate that the Haifanggou Formation in the Longhuitou Basin iscomposed of yellow-green-brown medium-coarse, poorly sorted, subangular toroundedpolymictic conglomerates, foldering several layers of purple fine-grained greywacke,yellow-green shale and carbonaceous mudstone.(2) The stratigraphic sequences of the Haifanggou Formation in the LonghuitouBasin are correlated to other typical area in western Liaoning. Their rock typesare basically similar and with same lithological associations, thus they could be correlatedwith each other. The differences between the Haifanggou Formations in several basins areexplained from their different tectonic positions and evolutionary levels of basin.(3) Terrestrial plant fossils and pollen fossils were found in the HaifanggouFormation of the Longhuitou Basin. The Podozamitaceae gen. indet. in the LonghuitouBasin belongs to the Coniopteris-Phoenicopsis flora of western Liaoning; Thepollen fossils in the Longhuitou Basin is named as Osmundacidites–Asseretosporaassociation. The Osmundacidites–Asseretospora are similar with the Cyathidites-Piceaepollenites in the Yan’an Formation of the Erdos Basin-Dongsheng area and theCyathidites-Classopollis in the Haifanggou Formation of Nanpiao area, indicating that theHaifanggou Formation in the Longhuitou Basin was formed in the Middle Jurassic. (4) The results of the conglomerate particle size and composition statistics and thesand particle size analysis from the Haifanggou Formation in the Longhuitou Basin showthat: this stratum is the piedmont depression alluvial fan face with the characteristics ofthe channel deposits and overflow deposition; the gravel of sedimentary conglomerate arefrom the underlain geological bodies (stratum) of surrounding areas and withoutlong-distance handling; This stratum is further divided to flowing sub-facies as root-fan,middle-fan and end-fan based on the characteristics of the lithology combination cycle.(5) The Longhuitou Basin is considered to be a piedmont sag basin by discussing theMesozoic tectonic setting and structural characteristics of this basin.更多还原