摘要
桂西下三叠统为海相沉积,根据其岩性、厚度、化石类型等诸方面的明显差异可以分为两种类型,即作登型和太平型。本文详细研究了桂西两种类型下三叠统的牙形石,认为不同类型的下三叠统具有不同的牙形石序列。在前人工作基础上,对桂西下三叠统牙形石序列予以重新厘定。补充了作登型下三叠统的Neogondolella carinta带;指出作登型下三叠统不宜建立Platyvillosus costatus带;在太平型下三叠统Dienerian阶—Spathian阶中新建了Pachvcladina erromera带,Platyvillosus costatus带,Pachycladina obliqua-Parachirognathus delicatulus带和Neospathodus triangularis带;指出了每一个牙形石带的性质并与作登型下三叠统牙形石序列进行了对比。本文还从事件地层学和生物地层学两个角度,对桂西二叠一三叠系界线提出了新的认识。
<ABSTRACT>
The Lower Triassic of western Guangxi is composed of marine deposits and can be divided into two types, i.e. Zuodeng type and Taiping type according to their differences in lithology, thickness and fossil contents. Detailed study of the conodonts in these two types has shown that there are two different types of conodont sequences in them. Based on studies made by former workers, the Lower Triassic conodont sequences of western Guangxi are collated and stipulated anew. The Neogondolella carinata zone of the Lower Triassic of Zuodeng type is supplemented. It should be pointed out that it is not suitable to establish Platyvillosus costatus Zone in the Lower Triassic of Zuodeng type, whereas Pachycladina erromera Zone, platyvillosus costatus Zone, Pachycladina obliqua - Parachirognathus delicatulus Zone and Neospathodus triangularis Zone are established in the Lower Triassic of Taiping type for the first time. The nature of each conodont Zone is indicated and the two types of Lower Triassic conodont sequences are compared. Furthermore, the Permian-Triassic boundary is supported both by evidences of biostratigraphy and event stratigraphy.
出处
《现代地质》
CAS
CSCD
1990年第2期1-15,T002,共16页
Geoscience
关键词
早三叠世
牙形石
广西
: western Guangxi, Lower Triassic, conodont
