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探讨了天文周期对基准面旋回的控制作用及应用离散小波变换和频谱分析技术识别天文周期并划分旋回层序的方法。地层基准面旋回是受天体运动控制的地球内、外动力地质作用的综合结果。因此,地层基准面旋回与天文周期相对应,基准面旋回层序为该过程的结果。应用离散小波变换法对GR曲线进行信号分解、重构及滤波,应用傅立叶分析法对小波分解结构重构信号进行频谱分析,以此确定了各细节分量主频及其比例。根据主频比例与天文频率比例之间的对应关系,判断出与各天文周期相对应的沉积旋回,并在绝对地质年龄约束下估算出各沉积旋回时限。计算结果显示,据细节分量划分的沉积旋回时限均两倍于对应的天文周期,如以天文周期为旋回层序划分依据,则每个沉积旋回可划分2个旋回层序,层序界面即位于地层叠加方式转换点。研究成果表明,以天文周期为依据,以小波变换及频谱分析为手段可以合理并有效地开展层序地层定年即等时对比。
The control effect of astronomical period on the cycle of reference plane and the method of identifying astronomical period and dividing the cycle sequence by discrete wavelet transform and spectrum analysis are discussed. Stratum basement cycle is controlled by the celestial movement of the Earth’s internal and external dynamic geology of the combined results. Therefore, the stratigraphic basement cycle corresponds to the astronomical cycle, and the reference plane cycle sequence is the result of this process. The signal of the GR curve is decomposed, reconstructed and filtered by using the discrete wavelet transform method. The spectrum of the reconstructed signal of the wavelet decomposition is analyzed by using the Fourier analysis method to determine the frequency of each detail component and its proportion. According to the correspondence between frequency ratio and astronomical frequency ratio, the sedimentary cycle corresponding to each astronomical period is judged, and the sedimentary cycle time is estimated under the constraint of absolute geologic age. The calculated results show that the sedimentary cycle time divided by detail components are twice as long as the corresponding astronomical periods. For example, the astronomical cycle is the basis of the gyration sequence, and each depositional cycle can be divided into two cycles. The sequence boundary is located at Stratigraphic stacking mode transition point. The research results show that, based on the astronomical period, it is reasonable and effective to carry out the isochronous stratigraphic dating by means of wavelet transform and spectrum analysis.