松辽盆地东岭地区泉头组高频沉积旋回的叠加型式分析

Analysis of High-frequency Sedimentary Cycle Superposition Type in Quantou Formation in Dongling Area of Songliao Basin

根据自然伽马测井曲线计算的旋回厚度,采用Fischer图解识别高频旋回的叠加型式,试图揭示湖相沉积中GR测井曲线反映的泥质含量波动与气候旋回的关系。选择松辽盆地东岭地区顶底清楚,地层连续的SN109井泉头组测井曲线中作为实验数据,根据极值点法共识别出1166个高频沉积旋回,旋回厚度变化于0.25~2.75 m之间,旋回平均厚度为0.62 m;根据Fischer图解,估算高频旋回的平均周期为17.2 ka,中频旋回周期在86.1~103.3 ka之间,低频旋回周期在305~416 ka之间,分别与米兰科维奇旋回岁差周期19~24 ka,轴斜率周期85~140 ka,偏心率周期350~400 ka存在着对应关系,说明SN109井泉头组湖相沉积旋回的形成受米兰科维奇气候旋回机制的控制。

According to calculative cycle thickness by the natural gamma logging curve,using Fischer plots to identify the high-frequency sedimentary cycle Superposition type,trying to proclaim the relation between GR logs reflective fluctuation of clay content and climate cycle. Choosing well SN109 natural gamma logging curve which possess clearly top and bottom and continuous layers in Dongling area of Songliao Basin as experimental data. Using the extreme point method,1 166 high-frequency depositional cycles can be identified. The thickness of these cycles change form 0.125 m to 2.75 m,the average is 0.62 m. According to Fischer plots,the estimation of the average period of high-frequency depositional cycles is 17.2 ka,the average period of medium-frequency depositional cycles is between 86.1 ~ 103.3 ka,the average period of low-frequency depositional cycles is between 305 ~ 416 ka,corresponding with 19 ~ 24 ka of the precession of equinox,85 ~ 140 ka of the short eccentricity,and 350 ~ 400 ka of the long eccentricity of Milankovitch cycles,respectively. It is suggested that the production of lacustrine depositional cycles of Quantou Formation was controlled by the Milankovitch cycles.