地层对比中层序地层学理论的运用——以滇东中下泥盆统为例

在滇东进行区域地质调查的过程中 ,详细研究了泥盆系中下统的层序地层 ,在不同地区 (武定盆地、昆明地区、曲靖盆地 )划分了若干个层序 (三级旋回 )、建立了各盆地的层序地层格架、估计了滨线上超三级旋回曲线。以此为基础 ,进行了盆地或地区间滨线上超旋回对比 ,发现其间具可比性。这种可比性对长期争议的滇东泥盆系中下统地层对比问题以及与之相关的盆地演化、构造作用、古地理轮廓、生物地层等问题的解决有很大的帮助。运用层序地层学理论进行盆地间地层对比的基本思路概括为 :　 1)对比的前提是对生物地层和构造作用进行详细而客观的研究 ;　 2 )对比的基础是各盆地建立层序地层格架 ,并估计出与沉积特征和范围尽可能协调的滨线上超旋回 ;　 3 )对比的关键标志是层序边界和凝缩段 ,此外 ,应该注意分布广泛的地质事件

Application of Sequence Stratigraphical Theory to the Correlation: Taking the Lower and Middle Devonian of Eastern Yunnan for Example

Using new methods of RGS, a special sequence stratigraphical theory, to the study of the Lower and Middle Devonian of Wuting Basin, Kunming District and Qujing Basin of Eastern Yunnan, permits establishing several sequences. Based on sequences, biostratigraphical and palaeostructural characters, sequence stratigraphical frameworks can be setted up and third order cycles of shoreline onlap can be appraised also. Further, the cycles can be used for correlation between the basins or districts, and the correlatability of the cycle does exist. The correlatability would be helpful to solving the problem of correlation, for example, basin evolution, tectonic process, outline of palaeogeography, biostratigraphy and so on. In the use of sequence stratigraphical theory for correlation, detailed and objective studies of biostratigraphy and tectonic process in or between the basins are the prerequisites for the correlation; setting up sequence stratigraphical framework and estimating shoreline onlap cycles in harmony with sedimentary features, was basic to the correlation; and the sequence boundary and condensed section are the key marks for the correlation. Besides, the widespread geological events should be given attention too.