大庆长垣姚家组高频层序地层与米兰科维奇旋回对应性

Correspondence Between High Frequency Sequences and Milankovitch Cycles of Yaojia Formation in Daqing Placanticline

选取典型取心井对大庆长垣姚家组进行高频层序划分,共识别出98个超短期旋回,33个短期旋回,9个中期旋回和3个长期旋回。同时大庆长垣姚家组自然伽马曲线频谱分析结果表明,该地层中很好地保存了米兰科维奇旋回。其中,偏心率短周期引起的沉积旋回厚度为2.679～3.972 m,地轴倾角周期引起的沉积旋回厚度为1.379～2.131 m,岁差周期引起的沉积旋回厚度为0.601～0.901 m。高频层序与米兰科维奇旋回之间存在着较好的一致性,高频层序中期旋回、短期旋回和超短期旋回大致分别与米兰科维奇旋回的偏心率长周期、偏心率短周期以及岁差周期对应。地球轨道变化所引起的湖平面变化是高频层序形成的主控因素。

Ten typical well cores were observed to study high-frequency sequence classification of Daqing Yaojia Formation in this paper.As a result,98 ultra-short-term cycles,33 short-term cycles,9 mid-term cycles and 3 long-term cycles were identified.Meanwhile,this paper analyzed the Milankovitch Cycles,based on the natural gamma curves of those wells.The result showed that Milankovitch Cycles were well preserved in the strata of Yaojia Formation.The thickness of long-period cycles caused by eccentricity ranges from 2.679 m to 3.972 m,the thickness of mid-period cycles caused by obliquity cycles ranges from 1.379 m to 2.131 m and the thickness of short-period cycles caused by precessions ranges from 0.601 m to 0.901 m.There is a good consistency between high-frequency sequences and Milankovitch Cycles.The mid-cycle,short-cycle and ultra-short-term cycles of high-frequency sequence are corresponding respectively to the long-period eccentricity,short-period eccentricity and the precession cycle of Milankovitch Cycles.Lake level change caused by the change of Earth＇s orbit is a major controlling factor of the formation of high-frequency sequences.