CAJ | 학술논문

在北京市门头沟区九龙山南坡中侏罗统的下窑坡组、上窑坡组和龙门组采集植物化石22属38种.统计资料表明,北京西山中侏罗世植物群以真蕨纲(27.6%)、苏铁纲(25%)和银杏纲(25%)为主,其中真蕨纲的Coniopteris、Cladophlebis分别出现5和17个形态种.本文通过现生近缘种类分析法和植物的生长状态分析研究古气候.研究表明,含量高的植物化石的现生近缘种类紫萁科、蚌壳蕨科和苏铁纲植物主要生长于温热潮湿的热带或亚热带气候区;Cladophlebis较高的分异度,苏铁纲大型的羽状复叶,木贼目宽大的茎干等植物特征,同样指示较为湿热的气候环境.因此,北京西山中侏罗世植物群反映一种温热潮湿的亚热带气候.并且,化石的属种和数量自下窑坡组、上窑坡组到龙门组的降低反映研究区气候由温热潮湿向干热方向的演变.
재북경시문두구구구룡산남파중주라통적하요파조、상요파조화룡문조채집식물화석22속38충.통계자료표명,북경서산중주라세식물군이진궐강(27.6%)、소철강(25%)화은행강(25%)위주,기중진궐강적Coniopteris、Cladophlebis분별출현5화17개형태충.본문통과현생근연충류분석법화식물적생장상태분석연구고기후.연구표명,함량고적식물화석적현생근연충류자기과、방각궐과화소철강식물주요생장우온열조습적열대혹아열대기후구;Cladophlebis교고적분이도,소철강대형적우상복협,목적목관대적경간등식물특정,동양지시교위습열적기후배경.인차,북경서산중주라세식물군반영일충온열조습적아열대기후.병차,화석적속충화수량자하요파조、상요파조도룡문조적강저반영연구구기후유온열조습향간열방향적연변.
Plant fossils of 38 species in 22 genera in Middle Jurassic were collected from Lower Yaopo Formation, Upper Yaopo Formation and Longmen Formation on the southern slope of the Jiulong Hill in Mentougou district, Beijing. Statistical data show that the Middle Jurassic flora of the Western Hills in Beijing is dominated by Filicopsida (27.6%), Cycadopsida (25%)and Ginkgopsida (25%), among which Coniopteris with 5 species and Cladophlebis with 17 species were found. The Nearest Living Relatives Method and morphologic features analysis were used to analyze palaeoclimate. The result indicates that the nearest living relative plants of dominant fossils are Osmundaceae, Dicksoniaceae and Cycadopsida, which mainly live in a humid-warm tropical or subtropical climate, and warm-humid climate is also identified from the diversity of Cladophlebis, large feathery compound leaves of Cycadopsida and coarse stems of Equisetales, etc. Consequently, the Middle Jurassic flora in the Western Hills of Beijing reflects a humid-warm subtropical climate. In addition, the climate had changed into drier and warmer according to the species and the quantity reduction of plant fossils from the Lower Yaopo Formation through Upper Yaopo Formation to Longmen Formation.