塔里木盆地中—下寒武统自然伽马测井曲线周期及其在沉积层序划分中的意义

The cycles filtered from natural gamma-ray logging curves of Lower-Middle Cambrian in the Tarim Basin and their significance in sedimentary sequence division

盆地的沉积充填能够反映出周期性地质过程和天文过程。塔里木盆地中下寒武统地层保存完整,有较完整的自然伽马(GR)曲线。利用环满加尔坳陷的13口钻井的自然伽马(GR)曲线,施行经验模态分解,得到0.3 Ma、2 Ma和11 Ma的周期。0.3 Ma的峰值对应地球轨道偏心率的40万年周期性变化,2 Ma周期对应冰川型海平面变化周期,11 Ma周期对应太阳能量变化周期或星际云团相遇周期。这些周期补充和校准了先前得到的地质或天文周期,并能帮助理解古气候变化周期和高频层序地层。

The sedimentary fill of a basin always reflects periodic geological and astronomical processes.The sequence of the Lower-Middle Cambrian in the Tarim Basin has been preserved well with no erosion and has some gamma-ray(GR)well logging curves.Thirteen GR curves in the Lower-Middle Cambrian around Manjiaer depression were applied to wave analysis in terms of the empirical mode decomposition,and the time cycles of 0.3 Ma,1~2 Ma and 10~11 Ma were obtained.The 0.3 Ma period corresponds to the change cycle of the earth's orbital eccentricity,the 1~2 Ma period to that of the glacier-type eustasy,and the 10~11 Ma period to that of the earth's rotation angular velocity or that of the solar energy.These periods have supplemented and corrected previous geological and astronomical cyclic sequence and are of significance in understanding both paleoclimate change and high frequency sedimentary sequence.