Abstract:

The Middle Jurassic palynomorphs from the Yan'an Formation in Dongsheng region of Nei Monggol，consist of 63 species of fossil spores and pollen grains belonging to 34 genera, of which two species were described as new. Based on statistical analysis of 3 863 specimens identified in 10 samples from Hantaichuan, Nianpanlianggou and Liugou sections, the sporo pollen assemblage from the Yan'an Formation in Dongsheng region was established, which is generally characterized by the slight dominance of gymnospermous pollen grains (generally attaining proportion of 51%-54%), whereas the pteridophytic spores reach 46%-49% in abundance. In comparison with those of adjacent regions as well as Eurasia and North America, the present sporo pollen assemblage is regarded to early Middle Jurassic (corresponding to Bajocian Stage) in geological age. According to the climatic conditions reflected by the palynoflora, the paleoclimate in Dongsheng region is suggested to be warm temperate or subtropical warm and humid during the early Middle Jurassic.

内蒙古东胜中侏罗世延安组孢粉组合

江德昕¹  王永栋^2*

(1.中国科学院兰州地质研究所,兰州,730000) ；2.中国科学院南京地质古生物研究所,南京,210008)

研究了内蒙古东胜罕台川、碾盘梁沟和柳沟3个剖面中侏罗世孢子花粉化石34属63种, 包括2个新种. 基于10个样品中发现的3 863粒孢子花粉化石的鉴定和统计, 建立东胜地区延安组孢粉组合.该组合中蕨类植物孢子有19属37种, 含量占46%～49%, 最低为39%.裸子植物花粉略占优势, 有15属26种,含量为51%～54%, 最高达61%.与国内外相关资料对比结果表明该孢粉组合的地质时代应属中侏罗世巴柔期.孢粉植物群反映研究区在中侏罗世早期为暖温带或亚热带的暖湿气候.

关键词 孢粉组合 巴柔期 延安组 古气候 内蒙古

*通讯作者 Email: ydwang@nigpas.ac.cn

Key words: poro pollen assemblage, Bajocian stage, the Yan'an Formation, Paleoclimate, Nei Monggol