济阳坳陷石炭-二叠系米氏旋回层识别

JINGYANG Carbon Rock Sunkenk Cyclic Layer Identification of Permian Meters

由米兰柯维奇天文轨道参数所诱导的旋回沉积序列普遍存在于地质记录中,识别米氏旋回层对于沉积作用分析和层序划分具有重要的意义。本文依据米兰柯维奇理论,结合研究区钻井资料,选取自然伽马测井数据进行小波变换,从测井曲线中识别米氏旋回,发现测井数据多尺度频谱结构与米氏周期模型在自上而下的A,B,C,D 4个层段相吻合,认为是地球轨道要素变化在沉积地层中的响应。对这些层段数据进行快速傅立叶变换,计算出了轨道力旋回的波长厚度,并据此估算了沉积速率和地层完整性。

Cycle sedimentary successions induced by Milankovitch astronomical orbital parameters are widely preserved in geological records. Detecting Milankovitch cyclothems has important significance for analysis of sedimentation and classification of sequences. Based on the Milankovitch theory and data from an exploration well the gamma--ray （GR） well--logs was selected and analyzed with continuous wavelet transform （CWT）. The Milankovitch cycles from the logging curves were identified. The multi--scale frequency architecture of the well--logs achieved, matched the cyclicity model of eccentricity （400, 100ky）, obliquity （40ka） and precession （23ka） well in the four sections, marked A, B, C and D from top downwards, which is thought to be the correspondence of sedimentary succession to the varying of the orbital factors of the earth. Doing Fast Fourier Transform （FFT） of the detected section, the wavelengths of the orbital forcing cycles were calculated. Also, the accumulation rate and the stratigraphic completeness were estimated.