三级层序界面野外露头的识别判断标志——以南盘江坳陷晚古生界地层为例

在岩性及岩相观察基础上以不同类型的米级旋回层序作为分层和描述地层的基本工作单元，把米级旋回层及其有序叠加形式作为识别三级层序的基础，通过野外露头的详细观察、描述认为：在南盘江坳陷晚古生界地层中SB1型层序界面是以区域平行不整合面、古风化壳、古土壤层、下伏地层的强烈白云石化以及沉积物转化面为识别标志；SB2型序界面是以沉积物转化面、地层结构转化面及古土壤层为识别标志：SB3型层序界面是以凝缩段直接覆盖在下伏地层之上为识别标志；SB型层序界面是以上下地层的岩性组合、地层结构转化面及年代地层为识别标志。

Identification Marks on the Field Outcrop of Three-grade Sequence Interface

The different types of meter-grade cyclic sequence act as the basic work unit in stratification and stratum portrayal on the basis of the lithology and lithofacies observation, and the meter-grade cyclic sequence and its ordered superposition are used as the foundation for the three-grade identification, it is thought as follows by the detail survey on the field outcrop: the SB1 type of sequence interface within the strata of the Nanpanjiang depression of the upper Paleozoic Erathem is marked by the regional parallel surface of unconformity, ancient weathering crust, paleosol stratum, violent dolomitization of underlying strata and conversion face of sediment; the SB2 type of sequence interface is identified by the conversion face of sediment, transformed surface of stratigraphic structure and soil stratum; the identification mark on the SB3 type of sequence interface is that the condensation sectors directly cover on the underlier; the SB type of sequence interface is identified by the lithology association of upper and lower strata, conversation face of stratum structure and chronostratigraphy.