基于米兰科维奇理论的高频旋回识别与划分——以琼东南盆地梅山组和三亚组地层为例

摘要

Natural gamma data from the wells LS-33A, YC-35B and ST-36A in different structures of the Qiongdongnan Basin have been used for spectral analysis and continuous wavelet transform. In different wells, the Miocene Sanya and Meishan Formations are mainly dominated by the 404 ka and 95 ka eccentricity cycles. A high-resolution astronomical timescale of each formation is established based on the analysis of cycle filter and Milankovitch cycle curve which controls strata development. Finally, the sequence stratigraphy of high-frequency cycles in the Sanya and Meishan Formations is divided and correlated by using short eccentricity cycle curve as the reference curve for the fifth-order sequence units. The investigation provides a new effective approach to build the correlating framework of high-resolution sequence in the offshore basins.%选择琼东南盆地不同构造带上的LS-33A、YC-35B和ST-36A 3口钻井为研究对象,对自然伽马数据进行频谱分析和连续小波变换,结果显示在不同钻井中,新近系梅山组和三亚组地层都主要受404 ka和95 ka偏心率周期控制.对该周期滤波分析后,选择控制各层段发育的主要米兰科维奇周期曲线,建立了各段地层的高分辨率天文年代标尺.最后,以短偏心率周期曲线作为五级层序划分的参考曲线,对三亚组和梅山组层序进行高频旋回地层划分与对比.该研究成果为近海海域盆地高频层序单元对比框架的建立提供了一种新的有效方法.