福建永安吉山剖面的再研究

Restudy of the Jishan section of Yongan, Fujian

1943年陈恺在福建进行地质调查时,将不整合于火山岩之上,赤石群之下的一套河湖相砂页岩统称为坂头系,后人改称为坂头组。标准剖面位于永安市西北约10km之坂头村。1945年斯行健研究了其中所含植物化石,有Ruffordia goepperti,Onychio-psis?sp.,Cladophlebis cf.dunkeri,Sagenopteris yunganensis,S.? dictyozamoides,

The Bantou Formation, proposed by Chen Kai in 1943, consists mainly at green beds (sandstone, siltstone, shale, with a few volcanic debris) containing plant, conchostracan, ostracod, sporo-pollen and fish.The type area is at Baibuqiao, Youngan.The Regional Geological Survey Team of Fujian made a section at Jishan, Youagan, in 1966, and based on the Bantou Formation well exposed at the section, took it as a typical section of the Bantou Formation.According to the lithological characters, the Jishan section can be divided into three parts: The lower part is composed of green beds (sandstone, siltstone, shale, with a few volcanic debris), many fossil plants, conchostracan, sporo-pollen respectively belonging to Onychiopsis-Ruffordia assemblage, Yanjitsthcria-Orthestheria fauna and Classopollis assemblage, it is similar to the type area; the middle part is composed of grey-black siltstone and shale, and the upper one is composed of conglomerate, sandstone.The fossil plants, conchostracan, sporo-pollen of the middle and upper part respectively belonging to Pieudofrene-lopsis-Ruffordia assemblage, Cratostracus-Ortfiestheriopsis fauna and Classopollis-Cicatricosi-sporites assemblage.The middle and upper parts of the Jishan section are not explose in type area.They may belong to another cycle of sedimentary.So that the Jishaa Formation was setted up in this paper.The thickness of Jishan Formation is more than 977m, the top of it was absent, and underlian by Bantou Formation.It may be correlated with the Xiaoxi Formation in the East Fujian, and is considered to be Aptian-Albian in age.