天津张贵庄晚二叠世孢粉植物群

LATE PERMIAN PALYNOFLORA FROM ZHANGGUIZHUANG, TIANJIN

天津张贵庄SR13号钻孔原归为石盒子组的地层近顶部发现了丰富的孢粉化石 ,这一组合兼具上石盒子组和孙家沟组孢粉组合的特征。一方面 ,它与上石盒子组 (特别是其上部 )组合有不少共同分子 ,在蕨类孢子和裸子植物花粉 (包括具肋花粉 )的含量比例上也可以与之对比 ,但缺乏一些标志分子。另一方面 ,在属种组成上 ,当前组合与已知的孙家沟组合也颇可比较 ,而且出现了一些中生代色彩的分子。这一组合的揭示与研究有助于提高人们对华北晚二叠世晚期孢粉植物群特征的认识。依据当前组合与已知相关孢粉组合的对比讨论 ,将其时代定为晚二叠世 ,并倾向于晚二叠世晚期 (对应于孙家沟组 )。

Summary Abundant and well preserved spores and pollen grains are first recovered from the core samples collected from the uppermost part of the so called Shihhotse Formation of the borehole SR13 near Zhangguizhuang, Tianjin (text fig.1). The sporo pollen assemblage is transitional between those of the Upper Shihhotse Formation and the Sunjiagou Formation. On the one hand, the present assemblage has many common elements with the known assemblages of the Upper Shihhotse Formation (especially its upper part), and the proportion of the pterydophytic spores and gymnospermous pollen (including striate forms) are also comparable, but the index species Microtorispora gigantea and Patellisporites meishanensis etc. of this stage have not been found. On the other hand, the present assemblage is also comparable with those of the known Sunjiagou Formation in composition (Table I). Some Mesophytic or Mesozoic characteristical elements, such as Lueckisporites ? sp., Jugasporites cf. schaubergeroides, Cyasthidites, Dictyophyllidites, Lundbladispora, Apiculatisporis spiniger, Klausipollenites angustus and possibly Classopollis , are present in this assemblage. Based on the detailed disccusion and correlation of the assemblage with the known assemblages, the assemblage is assigned to Late Permian of the three fold division and most probably late Late Permian in age (equivalent to Sunjiagou Formation).