Abstract: Mockina slovakensis is one of the important species of conodont in Norian period. It plays a significant role in stratigraphy and acts as an indication for certain distinctive sedimentary environments. In this study,a significant abundance of conodont species M. slovakensis was discovered in the limestone deposits located in the lower parts of the Dashuitang Formation in the Hongyan section of Baoshan,Yunnan. Based on the conodont biostratigraphy,the age of the sedimentary strata in this section has been constrained to the late Alaunian of Norian period. Its presence and abundance can provide valuable insights into the paleoenvironmental conditions and depositional settings. M. slovakensis is known for strong adaptability to a diverse living environments,including both shallow and deep oceanic environment,as well as restricted sea to open sea. However,various records indicate that M. slovakensis conodont indicates the restricted depositional environment. Considering the abundance of dominant M. slovakensis found in the Hongyan section of Baoshan,combined with previous studies on the sedimentary environment of the Dashuitang Formation in the Baoshan block,it is reasonable to conclude that the Baoshan area formed a restricted sedimentary basin during the Alaunian stage under a tectonic stretching setting. The results are helpful for understanding the evolution of the sedimentary environment during the Late Triassic period in eastern Tethys.

Key words: Norian, Late Triassic, conodont, Dashuitang Formation, restricted basin

摘要： Mockina slovakensis是晚三叠世诺利期一个重要的牙形石属种,除了具有重要的地层学作用之外,它还能够指示特殊的沉积环境。本次研究在云南保山红岩剖面上三叠统大水塘组下段灰岩中发现了大量牙形石M. slovakensis,其在地层中占据统治地位,据此将研究层位的时代限定为晚三叠世诺利期Alaunian晚期。有记录表明,当M. slovakensis在地层中占据统治地位时,往往指示出一种较为局限的沉积环境。综合此次研究在保山红岩剖面发现的大量占统治地位的M. slovakensis牙形石以及前人对保山地块大水塘组沉积环境研究的结果,推测在诺利期Alaunian晚期,保山地区应为拉张背景下形成的较为局限的沉积盆地。该研究成果有助于进一步了解晚三叠世特提斯东部的沉积环境演化。

关键词: 诺利期, 晚三叠世, 牙形石, 大水塘组, 局限盆地

CLC Number: 

• Q913