The Characteristics of Early to Middle Permian Sporopollen Assemblages in Pengzhuang,Shandong Province

The upper part of the Permian Taiyuan and Shanxi formations at Xibu 15 well in the Pengzhuang Coalfield,Shandong Province were studied.Fourteen samples were collected and all the samples contain relatively abundant sporomorph.The 37 genera and the 107 species of sporopollen fossils have been found after identification.According to the content change and vertical variation of sporopollen fossils in the strata,the sporopollen may be distinguished into two assemblages as follows(in ascending order):Ⅰ.Laevigatosporites-Granulatisporites(the upper part of the Taiyuan Formation),Ⅱ.Gulisporites cochlearius-Leiotriletes adnatus-Sinulatisporites sinensis(the Shanxi Formation).The main characteristics of the sporopollen assemblages in this area can be compared with that in other areas in North China.The geological time of the sporopollen assemblages should be the late Early Permian(assemblageⅠ)and the early Middle Permian(assemblageⅡ).Namely,the boundary between the Lower and Middle Permian in the Pengzhuang Coalfield should be placed at the bottom of the mudstone in the lower portion of the Shanxi Formation.Lastly,the palaeoclimatic pattern reconstructed by sporopollen characteristics provides further evidence for the boundary between the Lower and Middle Permian in this area.