为探讨滇黔桂盆地东北缘介于深水环境和浅水环境之间形成的下石炭统特点, 以环江孟洞剖面为例。根据孟洞剖面下石炭统的沉积特征、地层旋回性, 对环江孟洞剖面下石炭统进行了层序划分和沉积相识别。并通过与深水环境和浅水环境的对比, 发现孟洞剖面下石炭统位于深水环境和浅水环境之间的过渡地带, 其沉积环境和层序地层具有特殊性。研究结果: (1) 环江孟洞剖面下石炭统由“尧云岭组+英塘组+黄金组+寺门组+罗城组”这一特殊沉积序列构成, 可划分出三个三级层序SQ1、SQ2、SQ3。 (2) 环江孟洞剖面可识别出2种沉积相类型: 三角洲相、陆棚相。其中三角洲相可划分出三种亚相: 前三角洲亚相、三角洲前缘亚相、三角洲平原亚相。 (3) 环江孟洞剖面因含有尧云岭组、罗城组等大套碳酸盐岩层段而不同于深水环境下、以暗色泥页岩为主导的下石炭统, 也因含有英塘组深水沉积和寺门组海陆过渡相沉积区别于浅水环境下、以碳酸盐岩为主导的下石炭统。环江孟洞剖面下石炭统是形成于深、浅水环境之间的过渡地带, 这种特殊的沉积环境和层序地层可以为滇黔桂地区下石炭统的层序地层格架的精确构建提供了新的素材和重要线索。

In order to explore the characteristics of the Lower Carboniferous formed between the deep-water environment and the shallow-water environment in the northeast margin of the Dianqiangui Basin, taking the section of Mengdong in Huanjiang as an example. According to the sedimentary characteristics and stratigraphic cyclic features of the Lower Carboniferous at the Mengdong section, the sequence division and sedimentary facies identification of the Lower Carboniferous at the Mengdong section of the Huanjiang section were carried out. In addition, through the comparison with the deep-water and shallow-water environments, it is found that the of the Lower Carboniferous Mengdong section is located in the transition area between the deep-water environment and the shallow water environment, and its sedimentary environment and sequence stratigraphy have particularities. Findings: (1) The Lower Carboniferous of the Mengdong section is composed of a special sedimentary sequence of “Yaoyunling Formation + Yingtang Formation + Huangjin Formation + Simen Formation + Luocheng Formation”, which can be divided into three tertiary sequences SQ1, SQ2 and SQ3. (2) Two types of sedimentary facies can be identified in the Mengdong section of Huanjiang section: delta facies and shelf facies. Among them, delta facies can be divided into three facies: pro-delta facies, delta front facies, and delta plain facies. (3) The Lower Carboniferous at the Mengdong section is different from the Lower Carboniferous dominated by dark shale in the deep-water environment because it contains large sets of carbonate rock Strata stratum such as Yaoyunling Formation and Luocheng Formation. It is also distinguished from the carbonate-dominated Lower Carboniferous Strata stratum by the presence of deep-water sediments of the Yingtang Formation and the sea-land transition facies sediments of the Simen Formation, which are found in the shallow-water environments. The Lower Carboniferous at the Mengdong section of Huanjiang is formed in the transition area between deep-and shallow- water environments, and this special sedimentary environment and sequence stratigraphy can provide new materials and important clues for the accurate construction of the sequence stratigraphic framework of the Lower Carboniferous in the Yunnan-Guizhou-Guangxi area.