豫西北太原组的时代:来自类化石的证据

GEOLOGIC AGE OF THE TAIYUAN FORMATION IN NORTHWEST HENAN PROVINCE:EVIDENCES FROM FUSULINIDS(FORAMINIFERA)

在河南省焦作地区太原组典型剖面上,共鉴定出类11属18种及11个未定种。根据类的组合特征,建立了一个类化石带两个亚带:Sphaeroschwagerina延限带,Quasifusulina-Pseudofusulina组合亚带和Schwagerina-Boultonia组合亚带。类在该区的出现次序是:Sphaeroschwagerina→Pseudofusulina→Quasifusulina→Schwagerina,其组合特征与当时华北板块大规模海侵密切相关。根据焦作太原组L1灰岩中首现Sphaeroschwagerina及类的演替特征等证据,石炭系-二叠系(C-P)界线应在太原组L1灰岩之下,太原组应划归下二叠统。

The paper focused on a typical section of the Taiyuan Formation in Jiaozuo, Henan. Based on detailed section measurement and description, a total of 11 genera and 29 species （including 11 undetermined species） of fusulinids have been identified. According to the fusulinid assemblages, one zone and two subzones can be devided as follows, Sphaeroschwagerina zone; Quasifusulina-Pseudofusulina and Schwagerina-Boultonia subzones. The succession of fusulinids in Jiaozuo is Sphaeroschwagerina→Pseudofusulina→Quasifusulina→Schwagerina, and this evo- lutionary character was closely related to the widespread transgressions in North China. Based on the fact that Sphaeroschwagerina was firstly found in the No. 1 limestone, the boundary between Carboniferous and Permian in Jiaozuo should be placed at the base of the No. 1 limestone. Therefore, the Taiyuan Formation should be of the Lower Permian age.