贵州册亨中三叠统坡段组中上部石珊瑚及牙形石生物地层

摘要

To further determine the biological appearance and composition features of corals and conodonts in Poduan Formation,the geological age of Poduan Formation in south western part of Guizhou and the contrast relationship between conodonts and other categories,the typical section of Poduan Formation in Ceheng is selected to carry out the research on corals and conodont biostratigraphy.Three species of scleractinian corals,Pentasmilia zaitingnaensis,Pinacophyllum spizzensis and Gillastraea delicate,and one conodont zone,Neogondolella constricta are identified in middle-upper part of the Poduan Formation in Ceheng.Besides Neogondolella constricta,there are some other important conodonts:Neogondolella bulgarica,Neogondoela navicula,Neogondolella acuta,Neogondolella alpina alpine,Cratognathodus kochi,Ozarkodina tortilis,Prioniodina sp.,Lonchodina sp.,etc.in the Neogondolella constricta zone.Based on the analysis of conodonts characteristics and regional stratigraphical correlation,this conodont zone of the Poduan Formation can be comparable to the following synonym conodont zone:the upper member of Guanling Formation of Yangjuan-Chupiwa Section in Panxian of Guizhou,Guandaoyanqi of Guandao Section (2) in Luodain of Guizhou,Falang Formation of Mazheshao in Kaiyuan of Yunnan,and the stratigraphic age of the middle-upper part of the Poduan Formation,can be considered as the Illyrian substages of the Anisian stage (middle Triassic).%为进一步精确限定黔西南中三叠统坡段组的地质时代,论文选择贵州册亨中三叠统坡段组典型剖面开展了石珊瑚及牙形石生物地层研究,在中三叠统坡段组(中上部)识别出石珊瑚3属3种,它们包括Pentasmilia zaitingnaensis,Pinaco ph yllums pizzensis,Gillastraea delicate;识别出牙形石Neogondolella constricta带.该带除含有带分子外,还含有Neogondolella bulgarica,Neogondoela navicula,Neogondolella acuta,Neogondolella al pina al pina,Cratognathodus kochi,Ozarkodina tortilis,Prioniodina sp.,Lonchodina sp.等重要牙形石.通过对牙形石特征的分析和国内外同名带的对比,认为坡段组Neogondolella constricta带大体可与贵州省盘县地区羊圈—楚皮凹剖面中三叠统关岭组上段、贵州罗甸关刀(2)剖面关刀岩楔、和云南开远马者哨法郎组的同名化石带对比,进而确定贵州册亨地区坡段组含牙形石Neogondolella constricta带的地层时代为安尼期的Illyrian亚期.