论卡以头组的时代

GEOLOGICAL AGE OF THE KAYITOU FORMATION

中国科学院南京地质古生物研究所的有关人员 (1980 )曾做过大量地层古生物工作 ,证实卡以头砂页岩层或卡以头组的时代为三叠纪最早期 ,是飞仙关组底部地层的相变。“论卡以头组”一文认为该组下部的时代为二叠纪 ,上部则属三叠纪。对该文提供的地层古生物资料进行分析后 ,本文作者认为该论点缺乏证据 ,不能成立 ;将陆相的威宁哲觉剖面代替标准地点宣威羊场的过渡相剖面作为卡以头组的标准剖面 。

The Kayitou Formation in eastern Yunnan and western Guizhou is Early Triassic in age and represents the equivalent of the basal part of the marine Feihsienkuan Formation in southwestern China as proved by rather abundant biostratigraphic data. Recently, a paper, “On Kayitou Formation”, proposed a continental section of the Kayitou Formation from Zhejue, Weining, Guizhou Province as stratotype of the Kayitou Formation to substitute the traditional stratotypic section of the Kayitou Formation at Kayitou Village, Xuanwei, Yunnan Province. The paper regarded the lower part of the Kayitou Formation as Late Permian in age according to the plant fossils and palynomorphs. Analysing the palaeobotanical data provided by the paper (2001) shows that more than 50% of the plant fossils were misidentified. Therefore, the argument for the Permian age of the lower part of the Kayitou Formation is unconvincing, while the substitution of stratotype of the Kayitou Formation is unreasonable.