甘肃窑街中侏罗世植物群特征及古生态研究

本文对产于甘肃窑街中侏罗统窑街组地层的植物大化石进行了系统的研究，发现甘肃窑街中侏罗世植物群由31属63种组成。其中，银杏类植物7属23种，真蕨类植物7属14种，松柏类植物7属11种，苏铁类植物5属10种，楔叶类植物4属4种，分类位置不明化石1属1种。在研究植物群组成特征的基础上，通过对植物化石埋藏类型与化石类群生态学的分析，重建了古植物群落，总结了窑街植物群的古生态特征，并划分出四个群落，即划分为近岸湿地群落、山间低地—缓坡群落、山间高地群落、旱生群落等四个群落。根据植物群的整体特征、植物类群之间的比例关系、特征分子及其古生态特征及孢粉植物群特征，推断甘肃窑街盆地中侏罗世古气候为温暖潮湿的亚热带气候。Brachyphyllum及茨康目植物化石的存在，表明甘肃窑街中侏罗世气候环境存在季节性变化。

Characteristics of the Middle Jurassic Flora at Yaojie,Gansu Province, and its Paleoecological Significance

This study performed the systematic analyses for a large number of the fossil plants collected from the middle Jurassic Yaojie Formation in Yaojie, Gansu Province. The results show that the flora of the Yaojie Formation is composed of 63 species in 31 genera, including Ginkgopsida of 23 species in 7 genera, Filicopsida of 14 species in 7 genera, Coniferae of 11 species in 7 genera, Cycadopsida of 10 species in 5 genera,Sphenopsida of 4 species in 4 genera, Plantae insertae sedis 1 species in 1 genera. Based on the composition, taphonomy and paleoecology characteristics of the flora, this study reconstructed the ancient flora group and summarized paleoecoloical features of the Yaojie flora through analyzing the burial type and ecology of plant fossils. Four plant communities have been recognized in ascending order as follows: riparian hydrophyte community, llowland slow slope community, intermontain upland community, and xerophyte community. Based on the overall characteristics of flora, the proportion of taxa in flora, the characteristic molecules and their paleoecological characteristics and sporopollen assemblage, we can infer that the paleoclimate in the Yaojie Basin was warm and humid subtropical climate during the Middle Jurassic. The presence of Brachyphyllum and Czekanowskiales fossils shows that the climate in Yaojie of Gansu had a seasonal variation during the Middle Jurassic.