摘要：

晚二叠世—早三叠世是由古生代植物群向中生代植物群过渡的一个关键时期,但陆相植物化石记录不完整且较零散,陆地植物演变的研究相对较少。文中通过统计分析豫西地区多个剖面早二叠世—早三叠世的植物化石数据,采用网络分析方法,探讨了该地区早二叠世—早三叠世植物群特征、植物演变规律以及古气候变化。结果表明,豫西地区早二叠世主要发育湿生植物群,其中中期禹州植物群以楔叶类植物、树蕨型真蕨、大羽羊齿类植物为主,而晚期禹州植物群以楔叶类植物、中生代型真蕨、种子蕨门盾籽目、大羽羊齿类为主; 晚二叠世—早三叠世主要为旱生植物群,其中Ullmannia植物群以裸子植物为主导,松柏类植物占绝对优势,但同早二叠世相比,植物化石数量锐减; Voltzia植物群以松柏类植物、楔叶类植物和种子蕨类植物为主。豫西地区早二叠世—早三叠世植物群由湿生型逐步转变为旱生型,暗示该地区古气候也逐渐从暖湿转变为干热,其中晚二叠世—早三叠世植物化石数量锐减,可能与二叠纪与三叠纪之交的生物大灭绝有关。研究成果为进一步认识豫西地区早二叠世—早三叠世的植物演化及其古气候变迁以及二叠纪与三叠纪之交陆相生态系统提供重要支撑。

关键词: 植物化石, 网络分析, 古气候, 二叠纪, 三叠纪, 豫西地区

Abstract:

The late Permian to early Triassic period represents a critical phase in the transition from Paleozoic to Mesozoic flora. However,terrestrial plant fossil records from this era are fragmented and incomplete,leading to limited studies on terrestrial plant evolution. This study aims to investigate the characteristics of the flora,patterns of plant evolution,and paleoclimate changes in this region during this period. It employs statistical analysis of plant fossil data from various stratigraphic sections in western Henan,spanning from the Early Permian to the Early Triassic,combined with network analysis methods. The results indicate that during the Early Permian,Wetland flora developed in western Henan,with the mid-Yuzhou flora primarily comprising sphenophytes,tree fern-type filicales,and gigantopteridales. In contrast,the late-Yuzhou flora was characterized by the presence of sphenophytes,Mesozoic-type filicales,seed ferns of the Peltaspermales,and gigantopteridales. From the late Permian to the early Triassic,Xeric floras became predominant,with the Ullmannia flora largely comprised of gymnosperms,particularly conifers. During this period,the number of plant fossils significantly decreased compared to the Early Permian. The Voltzia flora,in turn,was distinguished by the presence of conifers,sphenophytes,and pteridospermopsida. The transition from Wetland to Xeric flora in western Henan,occurring from the early Permian to the early Triassic,indicates a gradual transition from a warm,humid climate to a dry and hot one. The significant decline in plant fossils from the late Permian to the early Triassic may be associated with the mass extinction event at the Permian-Triassic boundary. These findings offer critical insights into plant evolution,paleoclimate,and terrestrial ecosystem during this crucial transition from the Early Permian to the Early Triassic in western Henan.

Key words: plant fossils, network analysis, paleoclimate, Permian, Triassic, western Henan