北京地区大灰厂组孢粉组合及其地质意义

THE PALYNOLOGICAL ASSEMBLAGE AND STRATIGRAPHICAL SIGNIFICANCE FROM DAHUICHANG FORMATION IN BEIJING REGION

大灰厂组沉积在北京西部大灰厂一带发育良好。该组由陆相火山碎屑砂岩、粉砂岩、页岩及砾岩组成，富含狼翅鱼、叶肢介、拟蜉蝣等动物化石和孢子花粉化石，厚度１２０－２００米。与下伏东狼沟组整合接触，与上覆辛庄组假整合接触。其孢粉组合是以ｃｌａｓｓｏｐｏｌｌｉｓ占显著优势为特征（６０－８０％）．含有较多Ｃｉｃａｔｒｉｃｏｓｉｓｐｏｒｉｔｅｓ，Ｌｙｇｏｄｉｕｍｓｐｏｒｉｔｅｓ及少量Ｃｉｃａｔｒｉｃｏｓｉｓｐｏｒｉｔｅｓ、Ａｐｐｅｎｄｉｃｉｓｐｏｒｉｔｅｓ、Ａｅｑｕｉｔｒｉｒａｄｉｔｅｓ、Ｈｓｕｉｓｐｏｒｉｔｅｓ及Ｄｅｎｓｏｉｓｐｏｒｉｔｅｓｖｅｌａｔｕｓ，Ｄ．ｍｉｃｒｏｒｕｇｕｌａｔｕｓ等。与国内外早白垩世的孢粉组合比较，时代为早白垩世韦尔登期。属于旱的热带和亚热带气候。

The Dahuichang formation deposits are well-devoloped in Dahuichang region,western part Beijing.It is consists of terrestrial sandstone,siltstone,shale and conglomarate,being about 120-200m thick.It overlies conformably the Donglanggou formation and is covered disconformably or fault contact.by the Xinzhuang formation.A abundant fossils Lycoptera,Ephemeropsis,Eosestheria etc.and sporo-pollen have been fount in it.This palynological assemblage of Dahuichang formation is characterized by are dominance position of classopollis(60-80%),with more Schizaeoisporites,Lygodiumsporites and rare Cricatricosisporites,Aequitriradites,Hsuisporites,Densoisporites velatus,D.microrugulatus,Appendicisporites etc.Its age may be considered to be wealden.The above mention a palynological assemblage rellect the climate of this region was dry tropical and subtropical.