甘肃永昌早二叠世两种科达叶的微细构造及古大气CO_2浓度重建

CUTICULAR STRUCTURE OF TWO LOWER PERMIAN SPECIES OF CORDAITES UNG.FROM YONGCHANG,GANSU,NORTHWESTERN CHINA AND PALAEOATMOSPHERIC CO_2 RECONSTRUCTION

角质层微细构造是鉴定植物属种的重要特征之一,近年来又在古气候恢复中得到广泛应用。从甘肃永昌下二叠统采获了角质层保存较好的两种科达叶化石,详细分析了表皮微细构造特征,并结合其外形特征进行了属种鉴定:其中一种鉴定为淮南科达(Cordaites huainanensis Chen),另建立了一新种,命名为永昌科达(Cordaites yongchangensis sp.nov.)。本文选取与化石标本的宏观形态和角质层微观形态较为相似的长叶竹柏(Podocarpus fleuryi Hickel)作为其现存最近对应种,初次尝试利用化石气孔特征重建了甘肃永昌早二叠世的古大气CO2浓度。

Cuticular structure is one of the important characteristics to identify fossil plants, and it was recently used to reconstruct palaeoatmospheric CO2 concentration. The authors collected fossil materials of two species of Cordaites Ung. from the Lower Permian of Yongchang, Gansu Province, NW China and analyzed their cuticular characteris tics. The fossils were identified mainly based on cuticular features, combined with gross morphology. One of the fossils was named Cordaites yongchangensis sp. nov. as a new species, and another was categorized as Cordaites huain anensis. Macro- and micro-characteristics of the fossils here in suggest their relevancy with the genus Podocarpus, particularly with Podocarpus fleuryi Hickel, a living counterpart. Then the CO2 concentration of the Early Permian is reconstructed by performing stomatal frequency analysis of these Cordaites fossils.